JP5767926B2 - Inkjet recording device - Google Patents

Description

  Embodiments described herein relate generally to an inkjet head that ejects ink to form an image on a recording medium, and an inkjet recording apparatus including the head.

  An inkjet head used in an inkjet printer or the like forms an image on a recording medium by selectively ejecting ink from a plurality of nozzles. In order to obtain good image quality by image formation using this type of head, it is necessary to maintain good ink ejection performance from the nozzles.

  Many of the deterioration factors of the ink ejection performance are ink clogging caused by drying of the ink in the nozzle when ink ejection is stopped. Ink clogging is likely to occur when the temperature of the ink is low, that is, when the viscosity of the ink is high. On the other hand, when the temperature of the ink is high, that is, when the viscosity of the ink is low, ink clogging is less likely to occur, but an extreme decrease in the viscosity causes deterioration in ink ejection performance.

  Conventionally, in order to prevent ink clogging, a method of vibrating the ink in the nozzles so as not to be ejected from the nozzles has been proposed. However, if the temperature of the ink rises excessively due to heat generated when the ink in the nozzle is vibrated, the ink viscosity may be drastically lowered as described above, and the ink discharge performance may be deteriorated.

JP 2004-230775 A

  SUMMARY OF THE INVENTION The problem to be solved by the present invention is an ink jet head that maintains an ink temperature at an appropriate value while preventing the occurrence of ink clogging in a nozzle and exhibits good ink discharge performance, and an ink jet recording apparatus having the head Is to provide.

In order to solve the above-described problems, an ink jet recording apparatus according to an embodiment includes a plurality of pressure chambers filled with ink, a plurality of actuators that respectively change volumes of the pressure chambers, and the pressure chambers. In accordance with the change in volume, ink is ejected from the plurality of nozzles for ejecting ink in the pressure chamber, a temperature sensor for detecting the temperature of the ink, and a recording medium for forming an image. A transport mechanism for transporting to a position and a controller are provided. The plurality of nozzles are arranged in a plurality of phases along a direction orthogonal to the conveyance direction of the recording medium and at a certain distance in the conveyance direction of the recording medium. The controller supplies an ejection signal for ejecting ink from the nozzles to a part of the actuators corresponding to nozzle rows of the same phase , and the ink supplies the meniscus of ink in the nozzles to the nozzles. Vibration signals to vibrate to the extent that they are not discharged from the sensor at a frequency corresponding to the temperature detected by the temperature sensor, and the remaining timing corresponding to the nozzle rows of the same phase at the timing when the discharge signals are supplied to the partial actuators. And a controller for supplying to the actuator.

1 is a diagram illustrating a mechanism of an ink jet recording apparatus according to a first embodiment. 2 is a diagram showing a system configuration of the ink jet recording apparatus according to the embodiment. FIG. The figure which shows the structure of the inkjet head which concerns on the same embodiment. The figure which shows the cross section which follows the XX line of FIG. The figure which shows the positional relationship of a pressure chamber, a nozzle, etc. which concern on the same embodiment. The figure which shows the waveform of the discharge signal which concerns on the same embodiment. The figure which shows the supply timing of the discharge signal to the actuator of each phase which concerns on the same embodiment. The figure which shows the waveform of the vibration signal which concerns on the same embodiment. 6 is a flowchart showing the operation of the head driver according to the embodiment. The figure which shows the relationship between the detection temperature which concerns on the embodiment, and the supply frequency of a vibration signal. The figure which shows the drive waveform at the time of supplying the vibration signal which concerns on the embodiment with high frequency. The figure which shows the drive waveform at the time of supplying the vibration signal which concerns on the embodiment with medium frequency. The figure which shows the drive waveform at the time of supplying the vibration signal which concerns on the same embodiment infrequently. 9 is a flowchart showing the operation of a head driver according to a second embodiment. The figure which shows the relationship between the detection temperature which concerns on the embodiment, and the intensity | strength of a vibration signal. The figure which shows the drive waveform at the time of supplying the vibration signal which concerns on the embodiment with medium frequency. The figure which shows the drive waveform at the time of supplying the vibration signal which concerns on the same embodiment infrequently.

  Hereinafter, the first and second embodiments will be described with reference to the drawings.

(First embodiment)
First, the overall configuration of the inkjet recording apparatus 1 according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a schematic view showing the mechanism of the ink jet recording apparatus 1 according to the first embodiment. As shown in the figure, the ink jet recording apparatus 1 is provided in a housing 2 constituting an outer shell, a paper feed cassette 3 containing paper P, an image forming unit 4 for forming an image on the paper P, and an upper part of the housing 2. The paper discharge tray 5, the transport device 6 that transports the paper P along the transport path A 1 from the paper feed cassette 3 to the image forming unit 4 and the transport path A 2 from the image forming unit 4 to the paper discharge tray 5, And a reversing device 7 for reversing the front and back surfaces of the paper P.

  The image forming unit 4 holds the paper P on the outer peripheral surface and rotates the drum 40 as a transport mechanism and presses the paper P supplied by the registration roller pair 66 against the outer peripheral surface of the drum 40. A holding device 41 that attracts and holds the surface by electrostatic force, a maintenance device 42, and recording heads 43C, 43M, 43Y, and 43K that form images by ejecting ink onto the paper P held on the outer peripheral surface of the drum 40; A neutralizing / separating device 44 that neutralizes the paper P, delaminates the paper P from the drum 40 and supplies the paper P to the separation roller pair 67, and a cleaning device 45 that cleans the drum 40 are provided.

  The drum 40 includes a rotating shaft 40a, a cylindrical frame 40b as a conductive portion formed in a cylindrical shape with aluminum as a conductor, and a thin insulating layer 40c formed on the surface of the cylindrical frame 40b. A cylindrical shape having a certain length.

  The holding device 41 is a contact type charging device including a suction roller 46 made of a chargeable member. When the charge is supplied to the suction roller 46, the roller 46 is charged. At this time, when the paper P is conveyed between the suction roller 46 and the drum 40, an electrostatic charge is applied from the suction roller 46 to the paper P or the drum 40. The sheet P is attracted to the outer peripheral surface of the drum 40 by the electrostatic force based on the electrostatic charge.

  The recording head 43C corresponds to cyan, the recording head 43M corresponds to magenta, the recording head 43Y corresponds to yellow, and the recording head 43K corresponds to black. The recording heads 43C, 43M, 43Y, and 43K are disposed to face the outer peripheral surface of the drum 40. Each of the recording heads 43 </ b> C, 43 </ b> M, 43 </ b> Y, 43 </ b> K ejects ink from nozzles provided at a predetermined pitch, and forms an image on the paper P conveyed by the drum 40.

  In the following description, when the recording heads 43C, 43M, 43Y, and 43K are not particularly distinguished, they are simply referred to as the recording heads 43.

  The maintenance device 42 moves toward the recording heads 43C, 43M, 43Y, and 43K at a predetermined timing, and cleans the nozzle surfaces of the recording heads 43C, 43M, 43Y, and 43K.

  The static eliminator 44 includes a static eliminator 47 that neutralizes the paper P and a detacher 48 that peels the paper P from the surface of the drum 40 after static elimination. The static eliminator 47 includes a static eliminator roller 47a formed of a chargeable material. The electric charge is supplied from the static eliminator roller 47a to neutralize the paper P, thereby releasing the adsorption force and separating the paper P from the drum 40. Make it easy to do. The peeling device 48 includes a separation claw 48a. The leading end of the separation claw 48a is brought into contact with the drum 40 at a predetermined timing to peel the paper P held on the outer peripheral surface of the drum 40, and the separated paper P is separated. Supply to roller pair 67.

  The conveyance device 6 includes a plurality of guide members 61, 62, and 63 provided along the conveyance paths A1 and A2, a plurality of conveyance rollers provided along the conveyance paths A1 and A2, and the like. As the transport rollers, a pickup roller 64 that feeds the paper P from the paper feed cassette 3 to the transport path A1, a pair of paper feed rollers 65 that transports the paper P sent by the pickup roller 64 along the transport path A1, and this supply roller. A registration roller pair 66 that supplies the paper P conveyed by the paper roller pair 65 to the image forming unit 4, a separation roller pair 67 that supplies the paper P on which image formation has been completed to the conveyance path A 2 or the reversing device 7, and this separation roller A conveyance roller pair 68 that conveys the paper P supplied by the pair 67 along the conveyance path A2 and a discharge roller pair 69 that discharges the paper P conveyed by the conveyance roller pair 68 to the paper discharge tray 5 are provided. It has been.

  The reversing device 7 is provided between the transport path A 1 and the transport path A 2, reverses the front and back of the paper P supplied by the separation roller pair 67, and supplies it again to the registration roller pair 66. The reversing device 7 may use any known mechanism such as a mechanism that switches back the paper P so that the front and rear direction is reversed. By reversing the paper P by the reversing device 7, double-sided printing on the paper P becomes possible.

  FIG. 2 is a block diagram showing a system configuration of the inkjet recording apparatus 1. As illustrated, the inkjet recording apparatus 1 includes a CPU (Central Processing Unit) 100 that functions as a controller. The CPU 100 is connected to a ROM (Read only memory) 101, a RAM (Random Access Memory) 102, an interface (I / F) 103, an operation panel driver 104, and a transfer line via a bus line including an address bus and a data bus. A driver 105, a holding roller rotation driver 106, a charging driver 107, a head driver 108, a static elimination driver 109, a peeling driver 110, a paper reversing driver 111, a maintenance driver 112, and a cleaning driver 113 are connected.

  The ROM 101 stores fixed data such as a computer program executed by the CPU 100. The RAM 102 is a main memory that forms various work memory areas and temporarily stores image data.

  The interface 103 communicates with an external device via a communication cable, and inputs print data and the like to the inkjet recording apparatus 1 and outputs data to the external device. The operation panel driver 104 controls the operation panel 120 including various operation buttons and a display with a touch panel.

  The transport driver 105 drives a transport motor 121 that rotates each transport roller included in the transport device 6. The holding roller rotation driver 106 drives a holding roller motor 122 that rotates the drum 40. The charging driver 107 charges the suction roller 46.

  The head driver 108 functions as a control unit in the present embodiment, and drives the recording heads 43C, 43M, 43Y, and 43K to form an image on the paper P. The head driver 108 and the recording heads 43C, 43M, 43Y, and 43K constitute the inkjet head 201 according to the present embodiment.

  The neutralization driver 109 drives the neutralization roller 47a. The peeling driver 110 turns on / off the power supply to the solenoid coil connected to the separation claw 48 a and brings the separation claw 48 a into contact with and away from the drum 40.

  The paper reversing driver 111 drives a paper reversing motor 123 that operates the reversing device 7. The maintenance driver 112 drives a maintenance motor 124 that operates the maintenance device 42. The cleaning driver 113 drives a cleaning motor 125 that operates the cleaning device 45.

  Next, the configuration and operation of the inkjet head 201 will be described in detail.

  As shown in the cross-sectional view of FIG. 3, the recording head 43 includes an ink inlet 202a connected to an ink supply source, a common pressure chamber 203a for storing ink flowing into the ink inlet 202a, and the common pressure chamber 203a. A plurality of pressure chambers 204a filled with ink, partition walls 205a partitioning these pressure chambers 204a and common pressure chambers 203a, a plurality of ink ejection nozzles 206a communicating with each pressure chamber 204a, and one wall surface of each pressure chamber 204a A plurality of diaphragms 207a, a plurality of piezoelectric elements 208a disposed on the diaphragms 207a, and a temperature sensor 209a for detecting the temperature of ink in the common pressure chamber 203a.

  The recording head 43 includes an ink inlet 202b connected to an ink supply source, a common pressure chamber 203b that stores ink flowing into the ink inlet 202b, and a plurality of pressures that are filled with ink in the common pressure chamber 203b. Chamber 204b, partition walls 205b partitioning these pressure chambers 204b and common pressure chamber 203b, a plurality of ink ejection nozzles 206b communicating with each pressure chamber 204b, and a plurality of diaphragms 207b forming one wall surface of each pressure chamber 204b. The plurality of piezoelectric elements 208b respectively disposed on the vibration plate 207b and the temperature sensor 209b for detecting the temperature of the ink in the common pressure chamber 203b.

  Each diaphragm 207a and each piezoelectric element 208a constitute a plurality of actuators that change the volume of each pressure chamber 204a. When the volume of the pressure chamber 204a is expanded, the ink in the common pressure chamber 203a is introduced into the pressure chamber 204a. When the volume of the pressure chamber 204a contracts from the expanded state, the ink in the pressure chamber 204a is ejected as ink droplets from the corresponding nozzle 206a.

  Each diaphragm 207b and each piezoelectric element 208b constitute a plurality of actuators that change the volume of each pressure chamber 204b. When the volume of the pressure chamber 204b is expanded, the ink in the common pressure chamber 203b is introduced into the pressure chamber 204b. When the volume of the pressure chamber 204b contracts from the expanded state, the ink in the pressure chamber 204b is ejected as an ink droplet from the corresponding nozzle 206b.

  FIG. 4 shows a cross section along the line XX in FIG. 3 as seen in the direction of the arrow. That is, the pressure chambers 204b are adjacent to each other via the partition wall 210b. As shown in FIG. 5, the pressure chambers 204a are also adjacent to each other via a partition wall 210a.

  As shown in FIG. 5, the paper P conveyed by the drum 40 is conveyed in the direction indicated by the thick arrow. The pressure chambers 204a are arranged along a direction orthogonal to the transport direction of the paper P. The pressure chambers 204b are also arranged along a direction orthogonal to the transport direction of the paper P. The arrangement position of each nozzle 206a and the arrangement position of each nozzle 206b are staggered in the direction orthogonal to the conveyance direction of the paper P. The interval between the nozzles 206a is about 169.4 μm. This corresponds to a resolution of 150 dpi. The distance between each nozzle 206a and each nozzle 206b is about 84.7 μm. This corresponds to a resolution of 300 dpi.

  Each nozzle 206a is arranged along a direction orthogonal to the transport direction of the paper P, and forms a first nozzle row. The first nozzle row is a first-phase A-row nozzle row formed by a plurality of nozzles 206a every second from the first, and a position shifted from the A-phase nozzle row by a certain distance in the paper P conveyance direction. The B phase nozzle row formed by the second and every second to second nozzles 206a, the third phase and the B phase nozzle row being arranged at a position deviated from the B phase nozzle row by a certain distance in the paper P transport direction. It includes a C-phase nozzle row formed by a plurality of nozzles 206a every second to third.

  Each nozzle 206b is arranged along a direction orthogonal to the transport direction at a position displaced by a predetermined distance, for example, 5 mm, in the transport direction of the paper P from the first nozzle array, thereby forming a second nozzle array. The second nozzle row is a D-phase nozzle row formed by the first and every second nozzle 206b from the first, and is shifted from the D-phase nozzle row by a certain distance in the paper P conveyance direction. E-phase nozzle row formed by the second and every second to second nozzle 206b, and arranged at a position deviated from the E-phase nozzle row by a certain distance in the paper P transport direction. It includes an F-phase nozzle row formed by a plurality of nozzles 206b every third from the third.

  As shown in FIG. 6, the head driver 108 restores the expansion pulse P1 for expanding the volumes of the pressure chambers 204a and 204b and the volumes of the pressure chambers 204a and 204b from the expansion by the expansion pulse P1 to the steady state. The ground potential (pulse pause) P2, the contraction pulse P3 for contracting the volumes of the pressure chambers 204a and 204b, and the ground for returning the volumes of the pressure chambers 204a and 204b from the contraction by the contraction pulse P3 to the steady state, respectively. A voltage having a waveform including potential (pulse pause) P4 in order is output to each actuator.

  The expansion pulse P1, the ground potential P2, the contraction pulse P3, and the ground potential P4 constitute an ejection signal for ejecting one ink droplet. In the present embodiment, one pixel is formed by repeating this discharge signal three times at the maximum and outputting it to the same actuator. As a result, it is possible to form a four-tone image with one recording head 43. FIG. 6 shows a case where the ejection signal is output three times.

  The period of the expansion pulse P1 is T1 (μs), the period of the ground potential P2 is T2 (μs), the period of the contraction pulse P3 is T3 (μs), and the period of the ground potential P4 is T4 (μs). The expansion pulse P1 has a negative polarity, and the contraction pulse P3 has a positive polarity.

  In the period of the expansion pulse P1, the volume of the pressure chambers 204a and 204b is expanded, and the ink in the common pressure chambers 203a and 203b is introduced into the pressure chambers 204a and 204b. In the period of the ground potential P2, the volume of the pressure chambers 204a and 204b returns to the steady state from the expansion by the expansion pulse P1, and the ink in the pressure chambers 204a and 204b is ejected from the nozzles 206a and 206b. In the period of the contraction pulse P3, the volumes of the pressure chambers 204a and 204b contract, and in the period of the ground potential P4, the volumes of the pressure chambers 204a and 204b return to the steady state from contraction by the contraction pulse P3. By this contraction and return, vibration of ink in the pressure chambers 204a and 204b is suppressed.

  The period T1 of the expansion pulse P1 is set to a half value (= AL / 2) of the natural vibration period AL of the ink in the pressure chambers 204a and 204b, and is a period from the intermediate point of the expansion pulse P1 to the intermediate point of the contraction pulse P3. Is set to the natural vibration period AL, and the period from the intermediate point of the contraction pulse P3 to the intermediate point of the expansion pulse P1 of the next ejection signal is set to the natural vibration period AL.

  As shown in FIG. 7, the head driver 108 applies the drive voltage as shown in FIG. 6 to the actuators corresponding to the nozzles 206a of the first nozzle row in order (A phase, B phase, C phase nozzle row). And then the drive voltage is supplied in order (in order of D phase, E phase, and F phase nozzle row) to each actuator corresponding to each nozzle 206b of the second nozzle row. . In this way, the actuators corresponding to the nozzles 206a and 206b are driven to perform main scanning for forming an image for one line. The main scanning period by each nozzle 206a in the first nozzle array and the main scanning period by each nozzle 206b in the second nozzle array are both periods in which the sheet P is conveyed by 84.7 μm (equivalent to 300 dpi) by the drum 40. Is set.

  The positions of the ink droplets that land on the paper P from the A phase nozzle row, the B phase nozzle row, and the C phase nozzle row are the positions of the A phase nozzle row, the B phase nozzle row, and the C phase nozzle row in the transport direction of the paper P. Are the same in the transport direction of the paper P. Similarly, the positions of the ink droplets that land on the paper P from the D-phase nozzle row, the E-phase nozzle row, and the F-phase nozzle row are the positions of the D-phase nozzle row, the E-phase nozzle row, and the F-phase nozzle row that transport the paper P. Since they deviate from each other along the direction, they are the same in the transport direction of the paper P. Further, the distance between the first nozzle row and the second nozzle row (this embodiment) after the supply of the drive voltage to the first nozzle row until the drive voltage starts to be supplied to the second nozzle row is reached. The time when the paper P is transported by the drum 40 is set by 5 mm). Therefore, the position of the ink droplets that land on the paper P by the main scanning by each nozzle 206a of the first nozzle row and the position of the ink droplets that land on the paper P by the main scanning by each nozzle 206b of the second nozzle row are as follows. The same in the transport direction.

  The time difference between the centers of the expansion pulses P1 of the first drop of each phase is set to an integral multiple of the natural vibration period AL of the ink. For example, in the present embodiment, the period Tz from the midpoint of the contraction pulse P3 of the third drop of each layer to the midpoint of the expansion pulse P1 of the first drop of the next phase is set to 3AL. Thereby, the ejection cycle of ink droplets ejected in each phase is uniform, and the influence of residual vibration due to ejection of a certain ink droplet on the ejection of other ink droplets can be reduced or eliminated.

  In addition to the drive voltage as described above, the head driver 108 outputs a voltage having a waveform including a contraction pulse P5 for contracting the volumes of the pressure chambers 204a and 204b to each actuator, as shown in FIG. This waveform constitutes a vibration signal that vibrates the ink meniscus in the nozzles 206a and 206b to such an extent that the ink is not ejected.

  The period of the contraction pulse P5 is T5 (μs), and the potential thereof is positive. During the contraction pulse P5, the volumes of the pressure chambers 204a and 204b contract, and during the subsequent ground potential period, the volumes of the pressure chambers 204a and 204b return from the contraction due to the contraction pulse P5 to a steady state. As a result, the ink meniscus remaining in the nozzles 206a and 206b vibrates.

  The period T5 and the potential V1 of the contraction pulse P5 are set to such values that the ink remaining in the pressure chambers 204a and 204b and the nozzles 206a and 206b is not ejected from the nozzles 206a and 206b. Such a value may be determined empirically, experimentally or theoretically.

Next, the operation of the head driver 108 will be described.
The head driver 108 operates according to the flowchart of FIG. 9 when printing one page.
That is, first, the head driver 108 acquires print data for one page (ACT 11). The print data is input from an external device via the interface 103, for example, and stored in the RAM 102 by the CPU 100. The head driver 108 acquires the print data stored in this way from the RAM 102.

  After acquiring the print data for one page, the head driver 108 determines the gradation value of each pixel included in the one page for each of cyan, magenta, yellow, and black based on the acquired print data ( ACT12).

  Subsequently, the head driver 108 acquires the detected temperatures of the temperature sensors 209a and 209b of the recording heads 43C, 43M, 43Y, and 43K (ACT 13).

  Then, the head driver 108 determines the frequency of supplying the vibration signal to each actuator for each of the recording heads 43C, 43M, 43Y, and 43K based on the acquired detected temperature (ACT 14).

  The relationship between the detected temperature and the supply frequency of the vibration signal in this embodiment is shown in FIG. The head driver 108 supplies a vibration signal at a high frequency when the detected temperature is lower than 15 ° C., supplies a vibration signal at a medium frequency when the detected temperature is 15 ° C. or higher and lower than 40 ° C., and when the detected temperature is 40 ° C. or higher. Supply vibration signals at low frequency. As described above, by decreasing the frequency of vibrating the meniscus as the temperature of the ink is higher, it is possible to prevent the ink viscosity from being drastically reduced due to heat generated by driving each actuator. Note that the supply frequency corresponding to each of the recording heads 43C, 43M, 43Y, and 43K is, for example, the correspondence relationship of FIG. 10 using the average value of the detected temperatures of the temperature sensors 209a and 209b of the recording heads 43C, 43M, 43Y, and 43K. It may be determined based on.

  Furthermore, the vibration signal supply timing at each frequency will be described in detail with reference to the waveform diagrams of FIGS. 11, 12, and 13. FIGS. 11 to 13 show that the drive voltage for forming one pixel supplied to each actuator by the head driver 108 is a case where no ink is ejected (0 drop), and a case where a single drop is ejected (1 drop). It is a wave form diagram represented about each of the case where 2 drops are discharged (2 drops), and the case where 3 drops are discharged (3 drops). FIG. 11 corresponds to the case where the vibration signal is supplied with high frequency (detection temperature less than 15 ° C.), and FIG. 12 corresponds to the case where the vibration signal is supplied with medium frequency (detection temperature between 15 ° C. and less than 40 ° C.). 13 corresponds to the case where the vibration signal is supplied at a low frequency (detection temperature of 40 ° C. or higher).

  When supplying a vibration signal at a high frequency, as shown in FIG. 11, if it is 0 drop, the ejection signals of the first drop, the second drop and the third drop are sent to the other actuators corresponding to the same phase nozzle row. The vibration signal is supplied at the timing of supply, and if it is 1 drop, the vibration signal is supplied at the timing of supplying the ejection signals of the second drop and the third drop to other actuators corresponding to the nozzle row of the same phase. For example, the vibration signal is supplied at the timing when the third droplet ejection signal is supplied to the other actuators corresponding to the nozzle rows of the same phase, and if it is three drops, the vibration signal is not supplied.

  When the vibration signal is supplied at a medium frequency, as shown in FIG. 12, if the drop is 0 drop, the ejection signals of the first drop and the second drop are supplied to other actuators corresponding to the same phase nozzle row. A vibration signal is supplied, and if it is 1 drop, a vibration signal is supplied at the timing of supplying a second drop ejection signal to another actuator corresponding to the same phase nozzle row, and if it is 2 to 3 drops, a vibration signal is not supplied. .

  When supplying the vibration signal at a low frequency, as shown in FIG. 13, if the drop is 0 drop, the vibration signal is supplied at the timing of supplying the first drop ejection signal to other actuators corresponding to the nozzle row of the same phase. If it is 1 to 3 drops, no vibration signal is supplied.

  In either case of high frequency, medium frequency, and low frequency, the supply timing of the contraction pulse P5 of the vibration signal and the supply timing of the contraction pulse P3 of the discharge signal supplied to other actuators corresponding to the nozzle rows of the same phase To match.

  After determining the supply frequency of the vibration signal in ACT 14, the head driver 108 determines the gradation determined in ACT 12 of each pixel formed by the actuator for each actuator of each recording head 43C, 43M, 43Y, 43K. The waveform of the drive voltage supplied to each actuator when printing one page is determined by sequentially arranging the waveform of 0 to 3 drops corresponding to the supply frequency of the vibration signal determined in ACT 14 according to the value (ACT 15). ).

  Thereafter, as the paper P is conveyed by the drum 40, the actuators of the recording heads 43C, 43M, 43Y, and 43K are driven by the driving voltage having the determined waveform, and printing for one page is performed. At this time, since the drive voltage supplied to each actuator includes a vibration signal having a frequency corresponding to the detected temperature, each nozzle 206a, 206b of each recording head 43C, 43M, 43Y, 43K vibrates moderately. .

  If the print job is related to printing of a plurality of pages, the head driver 108 performs the process from the ACT 11 again and prints the next page. That is, the supply frequency of the vibration signal is changed for each page to be printed.

  As described above, the inkjet head 201 according to the present embodiment uses a vibration signal for vibrating the ink meniscus in the nozzles 206a and 206b to such an extent that the ink is not discharged from the nozzles 206a and 206b. Supplied to each actuator at a frequency according to If the meniscus is vibrated in this way, the ink in each of the nozzles 206a and 206b becomes difficult to coagulate, so that ink clogging can be prevented. Furthermore, by changing the supply frequency of the vibration signal according to the temperature of the ink, it is possible to control the amount of heat generated by the operation of each actuator, and to prevent an excessive increase in the temperature of the ink.

  In addition, the inkjet head 201 supplies a discharge signal to a part of the actuators, and supplies a vibration signal to the remaining actuators at the timing of supplying the discharge signals to the some actuators. In view of the fact that ink clogging is likely to occur at nozzles that have stopped ejecting ink, the amount of vibration signal supplied can be suppressed as much as possible by vibrating the meniscus in the nozzles that have stopped ejecting ink in this way. Can be efficient. Further, by matching the supply timing of the discharge signal and the vibration signal, more specifically, the timing of the contraction pulses P3 and P5 included in the discharge signal and the vibration signal, vibration caused by the operation of the actuator based on the vibration signal This makes it difficult to adversely affect ink ejection from the nozzles.

  In addition to these, the ink jet head 201 or the ink jet recording apparatus 1 according to the present embodiment has various suitable effects.

(Second Embodiment)
A second embodiment will be described.
Normally, the amount of heat generated by each actuator when vibrating the meniscus increases as the meniscus vibrates greatly, and decreases as it vibrates small. In view of this, in the present embodiment, the frequency of supplying the vibration signal is constant, the amplitude for vibrating the meniscus is changed by the vibration signal according to the temperature of the ink, and the amount of heat generated by each actuator is thereby controlled. Different from the first embodiment.
The configuration described with reference to FIGS. 1 to 7 in the first embodiment is the same in this embodiment. In addition, the same code | symbol is attached | subjected to the component same as 1st Embodiment, and duplication description is performed only when necessary.

The head driver 108 according to the present embodiment operates according to the flowchart of FIG. 14 when printing one page.
That is, first, the head driver 108 acquires print data for one page (ACT 21). The print data is input from an external device via the interface 103, for example, and stored in the RAM 102 by the CPU 100. The head driver 108 acquires the print data stored in this way from the RAM 102.

  After acquiring the print data for one page, the head driver 108 determines the gradation value of each pixel included in the one page for each of cyan, magenta, yellow, and black based on the acquired print data ( ACT22).

  Subsequently, the head driver 108 acquires the detected temperatures of the temperature sensors 209a and 209b of the recording heads 43C, 43M, 43Y, and 43K (ACT 23).

  Then, the head driver 108 determines an amplitude for vibrating the ink meniscus in each of the nozzles 206a and 206b for each of the recording heads 43C, 43M, 43Y, and 43K based on the acquired detected temperature (ACT 24). The amplitude for vibrating the meniscus increases as the strength of the vibration signal supplied to each actuator, that is, the potential of the contraction pulse P5 increases. Therefore, in the present embodiment, the potential of the contraction pulse P5 is determined for each recording head 43C, 43M, 43Y, and 43K in ACT24.

  FIG. 15 shows the relationship between the detected temperature in this embodiment and the potential of the contraction pulse P5. The head driver 108 sets the potential of the contraction pulse P5 to the potential V1 when the detection temperature is lower than 15 ° C., and sets the potential of the contraction pulse P5 to the potential V2 (when the detection temperature is 15 ° C. or higher and lower than 40 ° C. 0 <V2 <V1), and when the detected temperature is 40 ° C. or higher, the potential of the contraction pulse P5 is set to the potential V3 (0 <V3 <V2). Thus, by lowering the potential of the contraction pulse P5 as the ink temperature increases, an extreme decrease in ink viscosity due to heat generated by driving each actuator is prevented. Note that the potentials of the contraction pulses P5 corresponding to the recording heads 43C, 43M, 43Y, and 43K are shown in FIG. It may be determined based on the correspondence relationship.

  Furthermore, the vibration signal supply timing at each frequency will be specifically described with reference to the waveform diagrams of FIGS. 11, 16, and 17. When the vibration signal is supplied at a high frequency, the vibration signal at the potential V1 is supplied at the timing shown in FIG. 11 as in the first embodiment.

  When the vibration signal is supplied at a medium frequency, as shown in FIG. 16, if it is 0 drop, the ejection signals of the first drop, the second drop, and the third drop are sent to the other actuators corresponding to the nozzle row of the same phase. A vibration signal corresponding to the contraction pulse P5 of the potential V2 is supplied at the supply timing, and if it is one drop, the ejection signals of the second and third drops are supplied to the other actuators corresponding to the same phase nozzle row. A vibration signal corresponding to the contraction pulse P5 of the potential V2 is supplied. If there is 2 drops, the ejection signal of the third droplet is supplied to another actuator corresponding to the nozzle row of the same phase and corresponds to the contraction pulse P5 of the potential V2. The vibration signal is supplied, and if it is 3 drops, the vibration signal is not supplied.

  When supplying the vibration signal at a low frequency, as shown in FIG. 17, if the drop is 0 drop, the ejection signals of the first drop, the second drop, and the third drop are sent to the other actuators corresponding to the nozzle row of the same phase. A vibration signal corresponding to the contraction pulse P5 of the potential V3 is supplied at the supply timing, and if it is one drop, the ejection signals of the second and third drops are supplied to the other actuators corresponding to the same phase nozzle row. A vibration signal corresponding to the contraction pulse P5 of the potential V3 is supplied. If there are two drops, the ejection signal of the third droplet is supplied to another actuator corresponding to the nozzle row of the same phase, and this corresponds to the contraction pulse P5 of the potential V3. The vibration signal is supplied, and if it is 3 drops, the vibration signal is not supplied.

  In either case of high frequency, medium frequency, and low frequency, the supply timing of the contraction pulse P5 of the vibration signal and the supply timing of the contraction pulse P3 of the discharge signal supplied to other actuators corresponding to the nozzle rows of the same phase To match.

  After determining the potential of the contraction pulse P5 in ACT 24, the head driver 108 determines the gradation determined in ACT 22 of each pixel formed by the actuator for each actuator of each recording head 43C, 43M, 43Y, 43K. According to the value, the waveform of the drive voltage supplied to each actuator when printing one page is determined by sequentially arranging 0 to 3 drop waveforms corresponding to the intensity of the vibration signal determined in ACT 24 (ACT 25). .

  Thereafter, as the paper P is conveyed by the drum 40, the actuators of the recording heads 43C, 43M, 43Y, and 43K are driven by the driving voltage having the determined waveform, and printing for one page is performed. At this time, since the drive voltage supplied to each actuator includes a vibration signal having an intensity corresponding to the detected temperature, each nozzle 206a, 206b of each recording head 43C, 43M, 43Y, 43K vibrates moderately. .

  If the print job is related to printing of a plurality of pages, the head driver 108 performs processing from the ACT 21 again to print the next page.

  As described above, the ink jet head 201 according to the present embodiment vibrates the ink meniscus in the nozzles 206a and 206b with an amplitude corresponding to the temperature of the ink so that no ink is ejected from the nozzles 206a and 206b. Let Even in such a configuration, ink clogging of the nozzles 206a and 206b can be prevented by meniscus vibration as in the first embodiment, and the amount of heat generated by the operation of each actuator can be controlled to prevent excessive ink. Temperature rise can be prevented.

  Needless to say, the same effects as those of the first embodiment can be obtained.

(Modification)
The configurations disclosed in the above embodiments can be embodied by appropriately modifying each component in the implementation stage.

  For example, in each of the above embodiments, a case where pixels of four gradations are formed by ink ejection from one nozzle 206a, 206b has been illustrated. However, the configuration for vibrating the meniscus disclosed in each of the above embodiments can also be applied to the case where pixels having gradations of 3 or less or 5 or more are formed by one nozzle 206a, 206b.

  Further, in each of the above embodiments, the case where the supply frequency and intensity of the vibration signal are changed in the three stages shown in FIGS. 10 and 15 according to the temperature of the ink is exemplified. However, the supply frequency and intensity of the vibration signal may be changed in multiple stages depending on the ink temperature, or may be changed in only two stages.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] A pressure chamber filled with ink, an actuator for changing the volume of the pressure chamber, a nozzle for discharging ink in the pressure chamber in accordance with the change in the volume of the pressure chamber, and a temperature of the ink are detected. The temperature sensor supplies a discharge signal for discharging ink from the nozzle to the actuator, and a vibration signal for vibrating the meniscus of ink in the nozzle to such an extent that ink is not discharged from the nozzle. And a controller that supplies the actuator with a frequency according to a temperature detected by the sensor.
[2] The inkjet head according to [1], wherein the controller decreases the frequency of supplying the vibration signal to the actuator as the detected temperature is higher.
[3] A pressure chamber filled with ink, an actuator for changing the volume of the pressure chamber, a nozzle for discharging ink in the pressure chamber in accordance with the change in the volume of the pressure chamber, and a temperature of the ink are detected. A temperature sensor and an ejection signal for ejecting ink from the nozzle are supplied to the actuator, and the ink meniscus in the nozzle is not ejected from the nozzle with an amplitude corresponding to the temperature detected by the temperature sensor. And a controller that supplies a vibration signal for causing the actuator to vibrate to the actuator.
[4] The inkjet head according to [3], wherein the controller decreases the amplitude for vibrating the meniscus by the vibration signal as the detected temperature is higher.
[5] A plurality of the pressure chambers, a plurality of the actuators for changing the volumes of the pressure chambers, and a plurality of the nozzles for discharging ink in the pressure chambers as the volume of the pressure chambers changes. The controller supplies the ejection signal to a part of the actuators, and supplies the vibration signal to the remaining actuators at a timing of supplying the ejection signals to the actuators. The inkjet head according to any one of supplementary notes [1] to [4].
[6] The inkjet head according to any one of appendices [1] to [5], and a transport mechanism that transports a recording medium for forming an image to a position where ink is ejected from the nozzle. An ink jet recording apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording device, 4 ... Image formation part, 40 ... Drum, 43 ... Recording head, 100 ... CPU (controller), 108 ... Head driver, 201 ... Inkjet head, 203a, 203b ... Common pressure chamber (1st pressure) Chamber), 204a, 204b ... pressure chamber (second pressure chamber), 206a, 206b ... nozzle, 207a, 207b ... diaphragm (part of actuator), 208a, 208b ... piezoelectric element (part of actuator), 209a 209b ... temperature sensor, P1 ... expansion pulse, P2 ... ground potential, P3 ... contraction pulse, P4 ... ground potential, P5 ... contraction pulse, AL ... natural vibration period.

Claims (4)

A plurality of pressure chambers filled with ink;
A plurality of actuators each changing the volume of each pressure chamber;
A plurality of nozzles that respectively discharge ink in the pressure chamber in accordance with a change in the volume of each pressure chamber;
A temperature sensor for detecting the temperature of the ink;
A transport mechanism for transporting a recording medium for forming an image to a position where ink is ejected from the plurality of nozzles;
A controller,
With
The plurality of nozzles are arranged in a plurality of phases along a direction orthogonal to the conveyance direction of the recording medium and shifted by a certain distance in the conveyance direction of the recording medium,
The controller supplies an ejection signal for ejecting ink from the nozzles to a part of the actuators corresponding to nozzle rows of the same phase, and a meniscus of ink in the nozzles from the nozzles. Corresponding to the nozzle rows of the same phase at a frequency corresponding to the temperature detected by the temperature sensor and the timing at which the ejection signal is supplied to the partial actuators. jet recording apparatus characterized and Turkey be supplied to the rest of the actuator. The ink jet recording apparatus according to claim 1, wherein the controller decreases the frequency of supplying the vibration signal to the remaining actuators as the detected temperature is higher. A plurality of pressure chambers filled with ink;
A plurality of actuators each changing the volume of each pressure chamber;
A plurality of nozzles that respectively discharge ink in the pressure chamber in accordance with a change in the volume of each pressure chamber;
A temperature sensor for detecting the temperature of the ink;
A transport mechanism for transporting a recording medium for forming an image to a position where ink is ejected from the plurality of nozzles;
A controller,
With
The plurality of nozzles are arranged in a plurality of phases along a direction orthogonal to the conveyance direction of the recording medium and shifted by a certain distance in the conveyance direction of the recording medium,
The controller supplies an ejection signal for ejecting ink from the nozzles to a part of the actuators corresponding to the nozzle rows of the same phase, and a meniscus of ink in the nozzles of the temperature sensor. A vibration signal for causing the ink to vibrate so as not to be ejected from the nozzles with an amplitude corresponding to the detected temperature is supplied to the remaining actuator rows corresponding to the same phase nozzle row at the timing when the ejection signals are supplied to the partial actuators. jet recording apparatus characterized and Turkey be supplied to the actuator. 4. The ink jet recording apparatus according to claim 3, wherein the controller reduces the amplitude at which the meniscus is vibrated by the vibration signal as the detected temperature is higher.

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