JP6812652B2 - Liquid discharge device - Google Patents

Description

The present invention relates to a liquid discharge device.

In a liquid discharge device such as an inkjet printer, a pressure is applied to the liquid to discharge the liquid from a nozzle (discharge port) by using deformation (piezoelectric strain) when an electric field is applied to the piezoelectric element (actuator). It has been known.

For example, in the inkjet recording apparatus described in Patent Document 1, three or more head units that drip ink of the same color are arranged along the sub-scanning direction, and each head unit is located at the same position on the recording medium. It is arranged so as to drip (eject) ink of the same color. Each head unit includes a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles, and piezoelectric elements are arranged at positions facing the plurality of pressure chambers. Then, when a drive voltage is individually applied to these piezoelectric elements from the drive circuit, the volume of the pressure chamber is changed by utilizing the deflection deformation of the piezoelectric element, so that the liquid is discharged from the nozzle. .. Further, this inkjet recording device is configured so that the amount of ink ejected can be changed via the head drive unit.

Japanese Unexamined Patent Publication No. 2013-184447

Here, the inventor of the present application operates a drive circuit in a liquid discharge device as described above so that a large amount of liquid is discharged to a large number of nozzles of the head unit at the same timing. It has been found that an excessive current may cause a malfunction of the drive circuit, and as a result, a discharge abnormality may occur.

Therefore, an object of the present invention is to provide a liquid discharge device capable of suppressing the occurrence of a discharge abnormality.

In order to solve the above problems, the liquid discharge device of the present invention has a plurality of discharge ports for discharging liquid, a plurality of pressure chambers communicating with the plurality of discharge ports, and liquids in the plurality of pressure chambers. A head having a plurality of actuators for applying pressure to the device, a drive circuit that generates a drive signal having a predetermined drive waveform in each of the discharge cycles, and outputs the drive signal to each of the plurality of actuators, and the discharge port. Generates a plurality of types of waveform signals corresponding to any of a plurality of types of discharge amounts of liquid discharged from, and the length of each waveform is equal to the length of one discharge cycle. Then, one of the plurality of types of waveform signals is sent to the drive circuit according to the waveform signal generation circuit output to the drive circuit and the discharge data that defines the discharge amount of each of the plurality of discharge ports. In a liquid discharge device including a selection circuit that generates a selection signal for selection for each actuator and outputs the selection signal to the drive circuit, a temperature detecting means for detecting the environmental temperature of the liquid discharge device and The drive circuit further includes a discharge amount calculation means for calculating the total discharge amount of the liquid discharged from the plurality of discharge ports based on the discharge data, and the drive circuit uses the selection signal for each of the plurality of actuators. Correspondingly, one of the plurality of types of waveform signals is selected, the drive signal having a drive waveform corresponding to the waveform of the selected waveform signal is generated, and the plurality of types generated by the waveform signal generation circuit. The waveform signal is a first waveform signal group composed of a plurality of waveform signals in which the number of drive pulses for discharging liquid from the discharge port is less than a predetermined value, and the number of drive pulses is equal to or more than the predetermined value. A waveform classified into a second waveform signal group composed of a plurality of waveform signals having a corresponding discharge amount larger than that of the waveform signal of the first waveform signal group, and classified into the first waveform signal group. The signals have different discharge amounts corresponding to each other, and the second waveform signal group is composed of one or a plurality of waveform signal sets including a plurality of waveform signals having the same discharge amount. The plurality of waveform signals belonging to the same waveform signal set have the same number of drive pulses, and the transition times of rising and falling of the drive pulses do not overlap each other, and the waveform signal set In each, one of the plurality of waveform signals is defined as a standard waveform signal, and the selection circuit is the actuator. Said selection signal for each data when outputting to the drive circuit, the environmental temperature detected by said temperature detecting means is lower than the predetermined temperature, and, the total discharge amount calculated by the discharge quantity calculating means Tokoro If it is quantitative over, the when the discharge amount defined by the discharge data is a discharge amount corresponding to any of said one or more waveform signals set before Symbol second waveform signal groups, those waveform signal One is selected from the plurality of waveform signals in the set , a selection signal for causing the drive circuit to select the selected waveform signal is output, and the environmental temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature. If, or if the environmental temperature detected by the temperature detecting means is less than a predetermined temperature and the total discharge amount calculated by the discharge amount calculation means is less than a predetermined amount, the discharge data is used. When the specified discharge amount is a discharge amount corresponding to any one or a plurality of waveform signal sets of the second waveform signal group, the drive circuit is made to select the standard waveform signal of the waveform signal set. It is characterized by outputting a selection signal for the purpose .

The inventor of the present application states that when a drive signal in which the number of drive pulses is equal to or greater than a predetermined value is output from the drive circuit to the actuator, a large current flows in the drive circuit during the rising and rising transition times of the drive pulse of the drive signal. I found out. Further, the inventor of the present application causes the transition times of the drive pulses of the drive signals to overlap each other when the drive signals having the number of drive pulses of the predetermined value or more are output from the drive circuit to many actuators at the same time. Therefore, it was found that an excessive current is generated in the drive circuit, and as a result, a discharge abnormality may occur.
Therefore, in the present invention, when the waveform signal generation circuit generates the waveform signal that is the basis of the drive signal, for the waveform signal in which the number of drive pulses is equal to or more than a predetermined value, a plurality of waveform signals having the same drive pulse are used. The set of waveform signals is output to the drive circuit. Then, in the selection circuit, when the discharge amount defined by the discharge data is the discharge amount corresponding to the waveform signal set, one is selected from the plurality of waveform signals belonging to the waveform signal set, and the said Let the drive circuit select the selected waveform signal.
As a result, when the discharge amounts corresponding to the above waveform signal sets are simultaneously discharged from many discharge ports, a plurality of drive pulse transition times do not overlap each other for each of the actuators corresponding to these discharge ports. Any one of the drive signals can be selectively output. That is, since the number of actuators that output drive signals in which the transition times of the drive pulses overlap each other can be reduced, it is possible to suppress the occurrence of an excessive current in the drive circuit, and as a result, a discharge abnormality occurs. Can be suppressed.

It is a schematic side view of the inkjet printer by one Embodiment of this invention. (A) is a top view of the inkjet head shown in FIG. 1, and (b) is a bottom view of the inkjet head. (A) is an enlarged view showing the region III surrounded by the alternate long and short dash line of FIG. 2 (b), and (b) is a partial cross-sectional view taken along the IV-IV line of FIG. 3 (a). It is an electric block diagram of the inkjet printer shown in FIG. (A) is a diagram for explaining multi-valued data, and (b) is a diagram for explaining discharge data. (A) to (f) are diagrams showing waveform signals, and (e) is a diagram illustrating a transition time of a drive pulse. It is a figure explaining the signal set. It is a figure which shows the allocation table. It is an operation flow chart explaining the operation of a selection circuit.

Hereinafter, as a preferred embodiment of the present invention, the liquid ejection device will be applied to an inkjet printer and will be described with reference to the drawings. As shown in FIG. 1, the inkjet printer 101 includes an inkjet head 1 (hereinafter, head 1), a transport mechanism 20, a platen 25, a paper tray 26, a paper sensor 29, a temperature sensor 40 (see FIG. 4), and a control device 100. I have.

The transport mechanism 20 is a transport mechanism that transports the paper R to the head 1 along the transport direction from left to right in FIG. 1, and has a first transport unit 21 and a second transport unit 22. There is. The first transport unit 21 and the second transport unit 22 are arranged so as to sandwich the head 1 with respect to the transport direction of the paper R.

The first transport unit 21 has a pair of transport rollers 21a and 21b and a first motor 21c (see FIG. 4) that rotationally drives the transport rollers 21a and 21b. The pair of transfer rollers 21a and 21b are rotated in different directions (see arrows in the figure) by the first motor 21c to sandwich and convey the paper R supplied from the paper feed unit (not shown) in the transfer direction. .. A rotary encoder 28 is installed on the rotating shaft of the transport roller 21a. As the transfer roller 21a rotates, the rotary encoder 28 outputs a pulse signal associated with the rotation to the control device 100. The control device 100 controls the ejection timing of ink droplets from the head 1 based on the pulse signal output from the rotary encoder 28.

The second transport unit 22 has a pair of transport rollers 22a and 22b having the same diameter as the transport rollers 21a and 21b, and a second motor 22c (see FIG. 4) that rotationally drives the transport rollers 22a and 22b. .. The transport rollers 22a and 22b are rotated by the second motor 22c in different directions (see the arrows in the figure) to receive the paper R transported by the first transport unit 21 and transport the paper R in the transport direction. It is further sandwiched and conveyed and discharged to the paper tray 26.

The platen 25 is arranged to face the discharge surface 2a described later of the head 1, and supports the paper R conveyed by the transfer mechanism 20 from below. At this time, a predetermined gap suitable for image recording is formed between the upper surface of the platen 25 and the discharge surface 2a.

Next, the head 1 will be described with reference to FIGS. 2 and 3. Note that FIG. 2A, which is a bottom view of the head body 2, schematically shows only six rows of discharge port rows 11 for convenience of explanation. Further, in FIG. 3A, the pressure chamber 92 and the discharge port 8 which are under the actuator unit 30 and should be indicated by a broken line are shown by a solid line.

As shown in FIG. 2, the head 1 has a substantially rectangular parallelepiped shape that is long in the main scanning direction, and is fixed to a support frame 3 (see FIG. 1) below the head 1. That is, the inkjet printer 101 is a line type printer. The head 1 has a head body 2 having a discharge surface 2a having a plurality of discharge ports 8 (see FIG. 2A) opened on the lower surface thereof, and a reservoir unit for storing ink supplied to the head body 2. (Not shown). The ink supplied from the cartridge is temporarily stored in this reservoir unit. Here, the main scanning direction is a direction orthogonal to the conveying direction (sub-scanning direction) of the paper R conveyed by the conveying mechanism 20 and parallel to the conveying surface of the conveying mechanism 20.

As shown in FIG. 2A, eight head units 5 are formed in the head main body 2. The head unit 5 has a trapezoidal section, and a plurality of discharge ports 8 are arranged in a matrix and at positions different from each other in the main scanning direction in the section. In the present embodiment, one head unit 5 is formed with 664 discharge ports 8.

All the discharge ports 8 related to the eight head units 5 (that is, all the discharge ports 8 of the head 1) are all projection points formed by projecting them vertically on an arbitrary virtual line extending in the main scanning direction. Have a positional relationship such that are arranged at equal intervals corresponding to a resolution of 600 dpi. Therefore, in the image recorded on the paper R, the ejection port 8 has one dot row composed of a plurality of dots (including non-ejection dots on which ink has not landed) along the transport direction (secondary scanning direction). Will correspond to.

The head 1 is controlled by the control device 100 to control the ink ejection interval (ejection cycle) so that the ink droplets from the ejection port 8 land on the paper R at intervals of 600 dpi in the sub-scanning direction. That is, in the present embodiment, both the main scanning direction resolution and the sub-scanning direction resolution are 600 dpi, and the main scanning direction and the sub-scanning direction are divided into grids at 1/600 inch intervals on the paper R, respectively. A plurality of dot-forming regions are defined. Further, in the present embodiment, in order to form an image on the paper R, there are four types (large droplets, medium droplets) of ink ejection amount (ink droplet volume) that can be ejected from the ejection port 8 of the head 1 within one ejection cycle. Drops, droplets, non-ejection). Therefore, what can be expressed by the dots formed on the paper R is the density in four stages according to the amount of ink ejected. As described above, in the inkjet printer 101 of the present embodiment, it is possible to perform four-gradation recording for each dot forming region defined on the paper R. Here, the ejection cycle is the time required for the paper R to be conveyed by a unit distance corresponding to the resolution in the sub-scanning direction, and is, for example, 50 μS.

Next, a specific configuration of the head unit 5 will be described. The eight head units 5 have the same configuration as each other, and include a flow path unit 9, an actuator unit 30 fixed to the upper surface 9a of the flow path unit 9, and a driver IC 35 (see FIG. 3B), respectively. An ink supply port 91b connected to the reservoir unit is opened on the upper surface 9a of the flow path unit 9. An ink flow path having an ink supply port 91b as one end is formed inside the flow path unit 9. The ink flow path is composed of a common ink flow path on the upstream side and a plurality of individual ink flow paths 93 on the downstream side. The common ink flow path includes a manifold flow path 91 and a plurality of sub-manifold flow paths 91a branched from the manifold flow path 91. The manifold flow path 91 has an ink supply port 91b at one end. The individual ink flow path 93 reaches the discharge port 8 from the outlet of the sub-manifold flow path 91a via the pressure chamber 92. The lower surface of the flow path unit 9 is a discharge surface 2a, and a large number of discharge ports 8 are arranged. Further, a large number of pressure chambers 92 are arranged on the fixed surface of the actuator unit 30 in the flow path unit 9 in the same manner as the discharge port 8.

In each head unit 5, the discharge port 8 is arranged so that 16 rows of discharge port rows 11 arranged in the main scanning direction are arranged in the transport direction. As shown in FIG. 3A, the 16 rows of discharge port rows 11 are classified into a first discharge port row 11a and a second discharge port row 11b according to the positional relationship with the sub-manifold flow path 91a. In the present embodiment, the two first discharge port rows 11a and the two second discharge port rows 11b share one sub-manifold flow path 91a, and the discharge ports 8 included in these four discharge port rows are pressure chambers. It communicates with the sub-manifold flow path 91a via 92.

Next, the actuator unit 30 will be described. The actuator unit 30 includes a plurality of actuators facing each pressure chamber 92. Each actuator selectively applies ejection energy to the ink in the pressure chamber 92 for each ejection cycle, which is a unit of time continuously in time. Specifically, the actuator unit 30 is composed of three piezoelectric sheets made of lead zirconate titanate (PZT) -based ceramic material having ferroelectricity. Each piezoelectric sheet is a continuous flat plate having a size straddling a plurality of pressure chambers 92. Individual electrodes 33 are formed at each of the positions of the uppermost piezoelectric sheet facing the pressure chamber 92. A common electrode 34 is interposed between the top-layer piezoelectric sheet and the lower piezoelectric sheet over the entire surface of the sheet.

The common electrode 34 is equally held at the ground potential in the region corresponding to all pressure chambers 92. On the other hand, the individual electrode 33 is electrically connected to the driver IC 35. Further, the driver IC 35 is connected to the control device 100.

As will be described in detail later, the driver IC 35 receives six types of waveform signals from the control device 100, and also receives a selection signal indicating any of these six types of waveform signals for each actuator (individual electrode 33). .. Then, the driver IC 35 selects one waveform signal indicated by the selection signal from the six types of waveform signals for each of the actuators of the actuator unit 30, and drives the driver IC 35 with a drive waveform corresponding to the waveform of the selected waveform signal. Generates and outputs a signal. As a result, the potential of the individual electrode 33 is switched between a predetermined drive potential corresponding to the pulse height and the ground potential according to the drive waveform of the drive signal. As a result, pressure (discharge energy) is applied to the ink in the pressure chamber 92, and ink droplets are discharged from the discharge port 8. In this way, in the actuator unit 30, the portion sandwiched between the individual electrode 33 and the pressure chamber 92 acts as an individual actuator, and a plurality of actuators corresponding to the number of pressure chambers 92 are built.

In the present embodiment, a predetermined drive potential is applied to the individual electrodes 33 in advance, a ground potential is once applied to the individual electrodes 33 each time there is a discharge request, and then a predetermined drive is again performed at a predetermined timing. A drive signal that applies a potential to the individual electrodes 33 is output from the driver IC 35. In this case, the pressure of the ink in the pressure chamber 92 drops at the timing when the individual electrode 33 reaches the ground potential, and the ink is sucked from the manifold flow path 91 into the individual ink flow path 93. After that, at the timing when the individual electrode 33 reaches the driving potential again, the pressure of the ink in the pressure chamber 92 rises, and ink droplets are ejected from the ejection port 8.

Returning to FIG. 1, the paper sensor 29 is arranged on the upstream side in the transport direction with respect to the head 1. The paper sensor 29 is a detection sensor for detecting whether or not the paper R exists at the detection position, with the position on the transport path upstream of the head 1 in the transport direction as the detection position. The control device 100 determines the ink ejection start timing from the head 1 based on the detection signal from the paper sensor 29. Specifically, the control device 100 determines the distance between the detection position and the head 1 (specifically, the discharge port 8 most upstream in the transport direction) from the time when the tip of the paper R is detected by the paper sensor 29. The time when the time obtained by dividing by the transport speed of is elapsed is determined as the ink ejection start timing.

The temperature sensor 40 (see FIG. 4) is a sensor for detecting the environmental temperature of the inkjet printer 101.

In the above configuration, when the paper R transported in the transport direction by the transport mechanism 20 passes through the region facing the discharge surface 2a, the ink discharged from the discharge port 8 formed on the discharge surface 2a of the head 1 The drops form dots (images are recorded). The paper R on which the image is recorded is further conveyed by the conveying mechanism 20 and discharged to the paper tray 26.

Next, the control device 100 will be described with reference to FIG. The control device 100 includes a main control circuit 50 that controls the operation of the entire inkjet printer 101, an image processing circuit 60 that performs image processing, and a recording processing circuit 70 that controls the head 1 and the transfer mechanism 20.

The main control circuit 50 includes a network interface 51, a CPU (Central Processing Unit) 52, a ROM (Read Only Memory) 53, a RAM (Random Access Memory) 54, a print data storage memory 55, a RIP CPU 56, a multi-value data storage memory 57, and It has a multi-value data transmission circuit 58.

The network interface 51 is connected to an external terminal device 200 such as a PC via a LAN or the like. The external terminal device 200 stores application software capable of creating data for printing, a printer driver for setting processing conditions of the inkjet printer 101, and the like. The external terminal device 200 activates the printer driver and converts the data created by the application software into print data described in PDL (page description language) or the like. Then, the external terminal device 200 transmits the converted print data to the inkjet printer 101.

Various programs executed by the CPU 52 and the RIP CPU 56 are stored in the ROM 53. The RAM 54 is used as a work area for the CPU 52 and the RIP CPU 56. The print data storage memory 55 stores print data received from the external terminal device 200 via the network interface 51.

The RIP CPU 56 performs known RIP (Raster Image Processing) processing on the print data stored in the print data storage memory 55 in accordance with the instruction from the CPU 52 to obtain multi-value image data (hereinafter, multi-value data). Generate. As shown in FIG. 5A, the multi-valued data are arranged along the transport direction in the region on the paper R where the inks ejected from the plurality of ejection ports 8 of the head 1 land and the dots are formed. A plurality of dot elements corresponding to the plurality of dots are arranged in an arrangement order according to the arrangement order according to the formation order of the plurality of dots corresponding to the plurality of dot elements. A dot element sequence is arranged for each discharge port 8. It is the image data to have. In the present embodiment, each dot element of the multi-valued data is set with a density value represented by 256 gradations. The multi-valued data generated by the RIP CPU 56 is stored in the multi-valued data storage memory 57.

The multi-value data transmission circuit 58 transmits the multi-value data stored in the multi-value data storage memory 57 to the image processing circuit 60 according to the instruction from the CPU 52.

The image processing circuit 60 is a circuit that generates ejection data by performing image processing such as known error diffusion processing (quantization processing) on the multi-valued data received from the main control circuit 50. The discharge data is quaternary data in which density values represented by four gradations are set for each dot element. In the discharge data shown in FIG. 5B, each of the four types of density values set for each dot element is shown as "00", "01", "10", and "11". These four types of density values correspond to four types of ejection amounts of ink that can be ejected from the ejection port 8 of the head 1 within one ejection cycle. Specifically, the concentration value of "00" corresponds to "non-discharge", the concentration value of "01" corresponds to "small drops", and the concentration value of "10" corresponds to "medium drops". Corresponds to, and the concentration value of "11" corresponds to "large drop". As described above, the discharge data is data that defines the discharge amount of each of the plurality of discharge ports 8 of the head 1. The amount of ink ejected from the ejection port 8 is larger in the order of "large droplet", "medium droplet", "small droplet", and "non-ejection". The image processing circuit 60 outputs the generated discharge data to the recording processing circuit 70.

Returning to FIG. 4, the recording processing circuit 70 is a circuit that performs image recording processing for recording an image on the paper R based on the quaternary data received from the image processing circuit 60, and is a receiving circuit 71 and a dot count for each area. It has a circuit 72, a rearrangement circuit 73, a mechanical system drive control circuit 74, and a head control circuit 75.

The receiving circuit 71 is a circuit that receives the discharge data transmitted from the image processing circuit 60. The area-specific dot count circuit 72 counts the number of dot elements for which the density value of “11” of the ejection data received by the reception circuit 71 is set for each area, from the head 1 for the paper R on one page. This is a circuit for calculating the total amount of ink ejected related to "large droplets" for each ejected area. Specifically, the area-specific dot count circuit 72 divides the discharge data of one page into a plurality of areas (for example, one area is an area composed of 16 × 16 dot elements), and “11” of each area. By counting the dot elements for which the density value of "" is set, the total amount of ink ejected related to "large droplets" in each area is calculated. In the present embodiment, the discharge port 8 corresponding to the dot element belonging to the same area belongs to the same head unit 5. The area-specific dot count circuit 72 outputs to the head control circuit 75 the total ink ejection amount related to the “large droplet” for each area calculated for each page. The rearrangement circuit 73 rearranges the discharge data received by the reception circuit 71 into data that matches the arrangement of the discharge ports 8 of the head 1.

The mechanical drive control circuit 74 is a circuit that controls the first motor 21c and the second motor 22c of the transport mechanism 20 based on the control signal from the CPU 52 to transport the paper R along the transport direction.

Based on the control signal from the CPU 52, the head control circuit 75 selects six types of waveform signals in which the length of each waveform is equal to the length of one discharge cycle, and one of the six types of waveform signals. This is a circuit that outputs a selection signal for causing the driver IC 35 to select the driver IC 35.

Each of the six types of waveform signals output from the head control circuit 75 to the driver IC 35 is a signal that is the basis of the drive signal output from the driver IC 35 to the individual electrodes 33. These six types of waveform signals correspond to any of the four types of density values in the discharge data. That is, the six types of waveform signals correspond to any of the four types of ejection amounts of ink that can be ejected from the ejection port 8 of the head 1 within one ejection cycle.

As shown in FIG. 6, these six types of waveform signals include a first waveform signal group in which the number of drive pulses P for discharging liquid from the discharge port 8 is less than 3, and a first waveform signal group in which the number of drive pulses P is 3 or more. It is classified into a second waveform signal group.

The first waveform signal group includes one non-ejection waveform signal in which the number of drive pulses P is zero (see FIG. 6A) and one droplet ejection waveform signal in which the number of drive pulses P is one (FIG. 6A). It is composed of a total of three waveform signals (see 6 (b)) and one medium drop discharge waveform signal (see FIG. 6 (c)) having two drive pulses P. The non-ejection waveform signal corresponds to "non-ejection" and the droplet ejection waveform signal becomes "small droplet" in four types of ejection amounts of ink that can be ejected from the ejection port 8 of the head 1 within one ejection cycle. Corresponding, the medium drop discharge waveform signal corresponds to "medium drop". As described above, the waveform signals classified into the first waveform signal group have different discharge amounts.

On the other hand, the second waveform signal group is one waveform signal set consisting of three types of large droplet ejection waveform signals A to C (see FIGS. 6 (d) to 6 (f)) in which the number of drive pulses P is 3. It is composed of. The three types of large-drop ejection waveform signals A to C belonging to the same waveform signal set all correspond to the "large droplet" of the four types of ink ejection amounts that can be ejected from the ejection port 8 within one ejection cycle. The corresponding discharge amounts are the same as each other. Further, in these three types of large drop discharge waveform signals A to C, the number of drive pulses P is the same, but the rising and rising transition times of the drive pulses P do not overlap each other. In the present embodiment, the waveform of the large drop discharge waveform signal B is the same waveform as the waveform signal obtained by delaying the large drop discharge waveform signal A for a predetermined time, and the waveform of the large drop discharge waveform signal C is the large drop discharge waveform signal. It is the same waveform as the waveform signal in which B is delayed for the predetermined time.

Here, the rising and rising transition times of the drive pulse P are, as shown in FIG. 6E, until the instantaneous value of the drive pulse P reaches the specified upper limit value from the specified lower limit value. It is a time including the transition time and the transition time until the instantaneous value of the drive pulse P reaches the specified lower limit value from the specified upper limit value. In the present embodiment, the upper limit value is defined as 90% of the peak value VO of the drive pulse P, and the lower limit value is defined as 10% of the peak value VO of the drive pulse P.

Hereinafter, the inventor of the present application will explain the reason for generating three types of large droplet discharge waveform signals A to C in which the transition times of the drive pulses P do not overlap each other as the waveform signals corresponding to the “large droplet” as described above. The problem that can occur when only one type of waveform signal corresponding to the "large drop" found by is generated will be described.

When the driver IC 35 outputs a drive signal to the actuator (individual electrode 33), a large current related to charge / discharge flows through the circuit of the driver IC 35 at the rising and falling edges of the drive pulse of the drive signal. In particular, when the driver IC 35 outputs a drive signal based on a waveform signal corresponding to a "large drop" to many actuators in the same discharge cycle, the transition times of the drive pulses of the drive signals overlap each other. As a result, an excessive current is generated in the circuit of the driver IC35. As a result, the driver IC 35 may malfunction, resulting in a discharge abnormality.

Further, when the ambient temperature of the inkjet printer 101 is low, the viscosity of the ink becomes high. Therefore, in order to eject the specified amount of ink from the ejection port 8, the drive voltage of the drive signal output from the driver IC 35 is increased. There is a need. In addition, when the environmental temperature is low, the resistance component in the circuit of the driver IC 35 becomes small. Therefore, when the ambient temperature of the inkjet printer 101 is low, an excessive current is concentrated and flows through the circuit of the driver IC 35. As a result, there is a high possibility that the driver IC 35 malfunctions and a discharge abnormality occurs.

As a result of diligent research to solve this problem, the inventor of the present application has the head control circuit 75 as the above-mentioned three types of large drop discharge waveform signals as the large drop discharge waveform signal which is the basis of the drive signal related to the "large drop". The driver IC35 is generated by generating A to C and controlling the head 1 so as to reduce the number of actuators that output drive signals related to "large drops" in which the transition times of the drive pulses P overlap each other in the same discharge cycle. It has been discovered that it is possible to prevent an excessive current from being concentrated and flowing in the circuit of the above, and as a result, it is possible to suppress the malfunction of the driver IC 35.

In the present embodiment, any one of the three types of large drop discharge waveform signals A to C is pre-assigned to each of the 664 discharge ports 8 (actuators) formed in each of the head units 5. .. Then, the head control circuit 75 is assigned to the ejection port 8 of the three types of large droplet ejection waveform signals A to C when ejecting ink having a "large droplet" amount of ink from the ejection port 8. The allocation process for controlling the driver IC 35 is executed so as to output the drive signal based on the large drop discharge waveform signal to the actuator corresponding to the discharge port 8.

In the present embodiment, this allocation process is performed only when a malfunction condition that is likely to cause a malfunction of the driver IC 35 is satisfied. Specifically, when the environmental temperature of the inkjet head 1 detected by the temperature sensor 40 is less than a predetermined temperature (for example, 10 degrees), a large current tends to flow in the circuit through the driver IC 35 due to the low temperature as described above. .. Further, when the total ejection amount of the ink related to the "large droplet" in any area calculated by the area-specific dot count circuit 72 is equal to or more than a predetermined amount, a large number of "large droplets" are emitted from a large number of ejection ports 8 at the same timing. There is a high possibility that the ink will be ejected, and a large current tends to flow in the circuit of the driver IC35. Therefore, in the present embodiment, the environmental temperature of the inkjet head 1 detected by the temperature sensor 40 is less than a predetermined temperature, and the "large droplet" of any area calculated by the area-specific dot count circuit 72 is involved. When the total amount of ink ejected is equal to or greater than a predetermined amount, it is assumed that the circuit of the driver IC 35 is likely to malfunction, and the malfunction condition is satisfied.

Further, when the head control circuit 75 does not satisfy the malfunction condition, the drive signal output to the actuator when ejecting a "large drop" of ink from the ejection port 8 is a uniform drive for all actuators. It is a signal (in this embodiment, a drive signal based on the large drop discharge waveform signal A). Hereinafter, a specific configuration of the head control circuit 75 will be described.

As shown in FIG. 4, the head control circuit 75 includes a waveform storage circuit 81, a waveform signal generation circuit 82, a selection circuit 83, and an allocation table storage circuit 84.

The waveform storage circuit 81 stores the above-mentioned six types of waveform signals that define the amount of ink ejected for each ejection cycle ejected from each ejection port 8. The waveform signal generation circuit 82 generates six types of waveform signals stored in the waveform storage circuit 81 and repeatedly outputs them to the driver IC 35.

Here, in the present embodiment, in order to suppress fluid crosstalk due to the volume change of the pressure chamber 92, the output is output to the actuator (individual electrode 33) corresponding to the discharge port 8 belonging to the first discharge port row 11a. The drive signal and the drive signal output to the actuator corresponding to the discharge port 8 belonging to the second discharge port row 11b are configured to have different phases from each other. Hereinafter, a specific description will be given.

The plurality of actuators of the actuator unit 30 are divided into two actuator groups, an actuator group related to the first discharge port row 11a and an actuator group related to the second discharge port row 11b. As shown in FIG. 7, the waveform signal generation circuit 82 uses the above six types of waveform signals as one signal set, and has a first signal set corresponding to the actuator group related to the first discharge port row 11a and a second discharge port. Two signal sets of the second signal set corresponding to the actuator group according to the row 11b are generated and output to the driver IC 35. Note that FIG. 7 illustrates only the large drop ejection waveform signals A to C in each signal set.

Each of the waveform signals belonging to the second signal set is a signal obtained by delaying each of the waveform signals belonging to the first signal set by a predetermined time (for example, 18 μS). Therefore, the phases of the first drive pulses P in the six types of waveform signals belonging to each of the two different signal sets are different from each other.

In the driver IC35, for each actuator belonging to the actuator group related to the first discharge port row 11a, a waveform signal selected according to the selection signal from the six types of waveform signals of the corresponding first signal set is used as a basis. Output the drive signal. Further, in the driver IC 35, for each actuator belonging to the actuator group related to the second discharge port row 11b, a waveform signal selected according to the selection signal from the six types of waveform signals of the corresponding second signal set is selected. Output the basic drive signal.

With the above configuration, the ink in the sub-manifold flow path 91a is contained in the plurality of individual ink flow paths 93 related to the first ejection port row 11a and in the plurality of individual ink flow paths 93 related to the second ejection port row 11b. Not sucked at the same time. As a result, fluid crosstalk can be suppressed.

As shown in FIG. 7, in the waveform signal generation circuit 82, between two different signal sets, three types of large drop discharge waveform signals A to C belonging to each of the signal sets rise up in the drive pulse P, respectively. And the waveform signal is generated so that the transition times of the falling edge do not overlap each other. As a result, it is possible to prevent the transition times of the large droplet discharge waveform signals from overlapping each other between the two signal sets, so that it is possible to further suppress the occurrence of an excessive current in the driver IC 35.

The allocation table shown in FIG. 8 is stored in the allocation table storage circuit 84. This allocation table is a table that defines the allocation of each of the discharge ports 8 (in other words, the actuator) of the head unit 5 to any of the three types of large drop discharge waveform signals A to C. In the allocation table, the number of discharge ports 8 assigned to each of the three types of large drop discharge waveform signals A to C is set to be substantially equal. Further, in the present embodiment, in the allocation table, the same type of large drop discharge waveform signal is assigned to the discharge port 8 belonging to the same discharge port row 11.

The selection circuit 83 generates a selection signal for each actuator to select one of the above six types of waveform signals according to the discharge data, and outputs the selection signal to the driver IC 35.

Specifically, the selection circuit 83 selects one of the above six types of waveform signals for each of the plurality of dot elements based on the density values set for each of the plurality of dot elements in the discharge data. Performs the selection process to select. The waveform signal selected for each of the dot elements is a drive signal output to the individual electrodes 33 corresponding to each discharge port 8 when the dots corresponding to the dot elements are formed on the paper R. This is the underlying waveform signal.

In this selection process, the selection circuit 83 has a non-ejection waveform signal, “01”, for a dot element for which a density value of “00” is set, regardless of whether or not the above-mentioned malfunction condition is satisfied. A small drop discharge waveform signal is selected for a dot element for which a density value is set, and a medium drop discharge waveform signal is selected for a dot element for which a density value of "10" is set.

On the other hand, the selection circuit 83 changes the selection method for the dot element for which the density value of "11" is set, depending on whether or not the malfunction condition is satisfied. That is, when the malfunction condition is satisfied, the selection circuit 83 refers to the allocation table stored in the allocation table storage circuit 84 from among the three types of large drop discharge waveform signals A to C. The large drop discharge waveform signal assigned to the discharge port 8 corresponding to the dot element is selected. On the other hand, when the malfunction condition is not satisfied, the selection circuit 83 selects the large drop discharge waveform signal A, which is a standard waveform signal, for the dot element for which the concentration value of “11” is set. To do.

As described above, the selection circuit 83 generates a selection signal indicating the selected waveform signal for each actuator and outputs the selection signal to the driver IC 35.

Hereinafter, the operation related to the selection process of the selection circuit 83 will be briefly described with reference to FIG. In the following, for convenience, the selection process for one head unit 5 will be described.

First, the selection circuit 83 determines whether or not the environmental temperature of the inkjet printer 101 detected by the temperature sensor 40 is less than a predetermined temperature (S1). Then, when it is determined that the environmental temperature is equal to or higher than the predetermined temperature (S1: NO), the selection circuit 83 determines that the malfunction condition is not satisfied, and proceeds to the process of S3. On the other hand, when it is determined that the environmental temperature is lower than the predetermined temperature (S1: YES), the selection circuit 83 is any area corresponding to the head unit 5 calculated by the area-specific dot count circuit 72. It is determined whether or not the total ejection amount of the ink related to the "large drop" of the above is equal to or more than a predetermined amount (S2). When it is determined that the total ejection amount of the ink related to the "large droplet" in any area is equal to or more than the predetermined amount (S2: YES), the selection circuit 83 considers that the malfunction condition is satisfied, and in S4 Move on to processing. On the other hand, when it is determined that the total ejection amount of the ink related to the "large droplet" in all areas is less than the predetermined amount (S2: NO), the selection circuit 83 considers that the malfunction condition is not satisfied. Move on to the processing of S3.

In the processing of S3, the selection circuit 83 selects one of the above six types of waveform signals for each of the plurality of dot elements based on the density values set for each of the plurality of dot elements in the discharge data. select. At this time, the large drop ejection waveform signal A, which is a standard waveform signal, is selected for the dot element for which the density value of “11” is set. When this process is completed, this process is terminated.

In the processing of S4, the selection circuit 83 selects one of the above six types of waveform signals for each of the plurality of dot elements based on the density values set for each of the plurality of dot elements in the discharge data. select. At this time, the selection circuit 83 refers to the allocation table from among the three types of large drop ejection waveform signals A to C for the dot element for which the concentration value of “11” is set, and the dot element concerned. The large drop discharge waveform signal assigned to the discharge port 8 corresponding to the above is selected. When this process is completed, this process is terminated.

As described above, the head control circuit 75 outputs two sets of signal sets containing six types of waveform signals as one signal set and a selection signal to the driver IC 35.

The driver IC 35 includes circuits such as a shift register, a latch circuit, a multiplexer, and a drive buffer (both not shown). The shift register converts the serial data for each discharge port 8 related to the selection signal received from the control device 100 into parallel data, and inputs the parallel data to the latch circuit. The latch circuit is a so-called D-flip-flop, and the parallel data input from the shift register is input to the multiplexer all at once. The multiplexer selects the waveform signal that is the basis of the drive signal from the six types of waveform signals based on the data input from the latch circuit, and inputs the waveform signal to the drive buffer. At this time, the multiplexer refers to each of the actuators belonging to the actuator group corresponding to the first discharge port row 11a with six types of waveform signals belonging to the first signal set corresponding to the first discharge port row 11a. Select one waveform signal from them. Further, for each actuator belonging to the actuator group corresponding to the second discharge port row 11b, one waveform signal is obtained from the six types of waveform signals belonging to the second signal set corresponding to the second discharge port row 11b. Select. The drive buffer amplifies the waveform signal input from the multiplexer to generate a drive signal, and outputs the drive signal to each of the actuators of the actuator unit 30.

As described above, according to the present embodiment, when the waveform signal generation circuit 82 generates the waveform signal that is the basis of the drive signal, three types of waveform signals are used for the large drop discharge waveform signal having the drive pulse P of 3 or more. Output to the driver IC35. Then, in the selection circuit 83, when the discharge amount defined by the discharge data is "large droplet", one of the three types of large droplet discharge waveform signals A to C is selected and selected. Let the driver IC 35 select the waveform signal. As a result, when a large number of ejection ports 8 simultaneously eject ink in an amount corresponding to "large droplets", the transition times of the drive pulses P are mutually different for the actuators corresponding to these ejection ports 8. Any one of three different types of large drop discharge waveform signals A to C can be selectively output. That is, since the number of actuators that output drive signals in which the transition times of the drive pulses P overlap each other can be reduced, it is possible to suppress the occurrence of an excessive current in the driver IC 35, and as a result, a discharge abnormality occurs. Can be suppressed. Further, when selecting one waveform signal from the three types of large drop discharge waveform signals A to C, the selection is easily performed by using the allocation table stored in the allocation table storage circuit 84. be able to.

Further, the actuator group corresponding to the first discharge port row 11a and the actuator group corresponding to the second discharge port row 11b output drive signals based on waveform signals belonging to different signal sets. Therefore, it is possible to suppress the occurrence of fluid crosstalk. Further, at this time, a drive signal based on the waveform signal of the same signal set is output to the individual electrodes 33 corresponding to the respective discharge port rows 11 belonging to the same discharge port row 11. As a result, the discharge timing can be the same between the discharge port rows 11 belonging to the same discharge port row 11.

Further, when the above malfunction condition is not satisfied, the ejection timing of ejecting "large drops" of ink can be the same within the same ejection cycle, so that the quality of the image recorded on the paper R is improved. Can be made to.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made as long as it is described in the claims.

In the embodiment above mentioned, the waveform-signal generating circuit 82 has been configured to generate three types of large droplet ejection waveform signal A~C as a waveform signal corresponding to "large droplet" particularly limited thereto It suffices as long as it generates two or more types of large drop discharge waveform signals.

Further, in the above-described embodiment, the second waveform signal group is composed of one set of waveform signal sets composed of three types of large droplet ejection waveform signals, but is composed of two or more sets of waveform signal sets. May be good. For example, the second waveform signal group is a waveform signal set consisting of a plurality of extra-large droplet ejection waveform signals having four drive pulses P corresponding to "extra-large droplets" having a larger ejection amount than "large droplets". You may also have more. The transition times of the drive pulses P do not overlap with each other also for the plurality of extra-large droplet discharge waveform signals. In this case, the inkjet printer 101 can record 5 gradations for each dot forming region defined on the paper R. Therefore, the waveform signal generation circuit 82 generates the plurality of oversized droplet ejection waveform signals in addition to the above-mentioned six types of waveform signals and outputs them to the driver IC 35. Further, in the allocation table stored in the allocation table storage circuit 84, in addition to the allocation of any of the three types of large drop discharge waveform signals of each of the discharge ports 8, any of the plurality of types of extra large drop discharge waveform signals. I also remember the assignment of. Then, in the selection circuit 83, when the density value set in the dot element is the density value corresponding to the "extra large drop" in the discharge data (pent value data), a plurality of types are referred to by referring to the allocation table. From the oversized drop discharge waveform signal, the oversized drop discharge waveform signal assigned to the discharge port 8 corresponding to the dot element may be selected. From the viewpoint of suppressing the generation of an excessive current in the circuit of the driver IC35, the transition times of the drive pulses P overlap each other even between the three types of large drop discharge waveform signals and the plurality of extra large drop discharge waveform signals. It is preferable not to.

Further, in the above-described embodiment, in order to suppress fluid crosstalk, the plurality of actuators of the actuator unit 30 are divided into two types of actuator groups, but are divided into three or more types of actuator groups. May be good. In this case, the waveform signal generation circuit 82 generates three or more types of signal sets corresponding to each of the three or more types of actuator groups and outputs them to the driver IC 35. Then, the driver IC 35 outputs a drive signal based on the waveform signal selected according to the selection signal from the six types of waveform signals of the corresponding signal set to each actuator belonging to each actuator group. It should be noted that, among the different signal sets, the phases of the first drive pulses P in the six types of waveform signals belonging to the signal sets are different from each other. At this time, from the viewpoint of suppressing the occurrence of an excessive current in the circuit of the driver IC 35, at least the transition times of the large droplet discharge waveform signals A to C do not overlap each other between different signal sets. preferable.

Further, in the above-described embodiment, the first waveform signal group is composed of waveform signals having less than 3 drive pulses P, and the second waveform signal group is composed of waveform signals having 3 abnormal drive pulses P. However, it is not particularly limited to this. For example, if the number of drive pulses P is such that the transition times of the drive pulses P of the two drive signals overlap each other and a discharge abnormality can occur, the first waveform signal group is a waveform signal having less than two drive pulses P. The second waveform signal group may be composed of waveform signals having two or more drive pulses P. That is, the medium droplet ejection ejected wave form signal corresponding to a "medium droplet" also may be prepared a plurality of types of ejection ejected wave shaped signal transition time do not overlap each other of the drive pulses P.

Further, the waveform signal generated by the waveform signal generation circuit 82 may have an additional pulse such as a cancel pulse in addition to the drive pulse P. The cancel pulse is a pulse for removing the residual pressure remaining in the pressure chamber 92 after ejecting the ink by the drive pulse P. Further, the waveform signal generation circuit 82 may generate a plurality of waveform signals having the same number of drive pulses P but having different discharge amounts by making the pulse widths of the drive pulses P different from each other. .. Further, in the above description, the waveform signal corresponding to "small drops" has one drive pulse, and the waveform signal corresponding to "medium drops" has two drive pulses, and "large drops". The waveform signal corresponding to "" has three drive pulses, and the waveform signal corresponding to "extra-large droplet" has four drive pulses, but the number of drive pulses P is particularly limited to this. It's not something.

In the above-described embodiment, in the allocation table stored in the allocation table storage circuit 84, the same type of large drop discharge waveform signal is assigned to the discharge port 8 belonging to the same discharge port row 11. It is not limited to this. For example, in the allocation table, the waveform signals assigned to the plurality of discharge ports 8 belonging to the same discharge port row 11 are arranged in the large drop discharge waveform signal A, the large drop discharge waveform signal B, and the large drop discharge waveform signal C. The allocation table may be specified so as to switch in the order of the large drop discharge waveform signal A .... Further, in consideration of the resistance of the circuit of the driver IC35, the value of the current generated in the circuit of the driver IC35 is minimized when "large droplets" are discharged from all the discharge ports 8 in the same discharge cycle. Allocation tables may be specified. Further, the allocation table stored in the allocation table storage circuit 84 may be configured to be appropriately changeable from the external terminal device 200 or the like via the network interface 51.

Further, in the above-described embodiment, the selection circuit 83 refers to the allocation table stored in the allocation table storage circuit 84 when selecting one waveform signal from the three types of large drop discharge waveform signals A to C. By doing so, the selection was made, but the selection is not particularly limited to this. For example, the selection circuit 83 may be configured to randomly select one waveform signal from the three types of large droplet ejection waveform signals A to C. Further, the selection circuit 83 evenly divides the actuator that outputs the drive signal based on the large drop discharge waveform signal in the same discharge cycle into three actuator groups, and for each actuator of the three actuator groups. , The waveform signal may be selected so that the drive signal based on the large drop ejection waveform signals different from each other is output.

Further, the area-specific dot count circuit 72 counts the density values set for each dot element in the ejection data for each area, so that the ink for each area ejected from the head 1 with respect to the paper R on one page It may be configured to calculate the total discharge rate. In this case, the selection circuit 83 determines whether or not the above-mentioned malfunction condition is satisfied by determining whether or not the total discharge amount in each of the calculated areas is equal to or greater than a predetermined amount. .. Further, in order to simplify the control, the area-specific dot count circuit 72 counts the density value set to "11" in units of one page, so that the ink is ejected from the head 1 with respect to the paper R on one page. It may be configured to calculate the total ejection amount of ink related to "large drops" per page. Further, the area-specific dot count circuit 72 calculates the total amount of ink ejected from the head 1 with respect to the paper R on one page by counting the density values set for each dot element in units of one page. It may be configured to do so. In these cases, the selection circuit 83 determines whether or not the above-mentioned malfunction condition is satisfied by determining whether or not the calculated total discharge amount per page is equal to or more than a predetermined amount. become.

Further, in the above-described embodiment, the inkjet printer 101 is a line printer that records an image with the head 1 fixed, but records while scanning the head in a direction intersecting the transport direction of the paper R. It is also applicable to so-called serial printers.

The present invention is also applicable to a liquid ejection device that ejects a liquid other than ink. Furthermore, it is not limited to printers, and can be applied to facsimiles and copiers.

1 Inkjet head (head)
35 Driver IC (Drive Circuit)
82 Waveform signal generation circuit 83 Selection circuit

Claims (6)

A head having a plurality of discharge ports for discharging a liquid, a plurality of pressure chambers communicating with the plurality of discharge ports, and a plurality of actuators for applying pressure to the liquid in the plurality of pressure chambers.
A drive circuit that generates a drive signal having a predetermined drive waveform and outputs the drive signal to each of the plurality of actuators in each discharge cycle.
A plurality of types of waveform signals corresponding to any of a plurality of types of discharge amounts of liquid discharged from the discharge port, and the length of each waveform is equal to the length of one discharge cycle. A waveform signal generation circuit that generates a signal and outputs it to the drive circuit,
A selection signal for causing the drive circuit to select one of the plurality of types of waveform signals is generated for each actuator according to the discharge data that defines the discharge amount of each of the plurality of discharge ports. In a liquid discharge device including a selection circuit that outputs to the drive circuit.
A temperature detecting means for detecting the environmental temperature of the liquid discharge device, and
Further provided with a discharge amount calculation means for calculating the total discharge amount of the liquid discharged from the plurality of discharge ports based on the discharge data.
The drive circuit selects one of the plurality of types of waveform signals for each of the plurality of actuators according to the selection signal, and produces the drive signal having a drive waveform corresponding to the waveform of the selected waveform signal. Generate and
The plurality of types of waveform signals generated by the waveform signal generation circuit are a first waveform signal group composed of a plurality of waveform signals in which the number of drive pulses for discharging liquid from the discharge port is less than a predetermined value. And, the number of the drive pulses is equal to or more than the predetermined value, and the discharge amount corresponding to the waveform signal of the first waveform signal group is larger than that of the waveform signal, and the second waveform signal group composed of a plurality of waveform signals is classified. Being done
The waveform signals classified into the first waveform signal group have different discharge amounts corresponding to each other.
The second waveform signal group is composed of one or a plurality of waveform signal sets including a plurality of waveform signals having the same discharge amount, and the plurality of waveform signals belonging to the same waveform signal set are each said. The number of drive pulses is the same, and the rising and falling transition times of the drive pulses do not overlap each other.
In each of the waveform signal sets, one of the plurality of waveform signals is defined as a standard waveform signal.
The selection circuit
When outputting the selection signal for each of the actuator to the drive circuit,
When the environmental temperature detected by the temperature detecting means is less than a predetermined temperature and the total discharge amount calculated by the discharge amount calculating means is equal to or more than a predetermined amount.
Wherein when the discharge amount defined by the discharge data is a discharge amount corresponding to any of said one or more waveform signals set before Symbol second waveform signal groups, those waveform signal set of the plurality of waveforms One is selected from the signals, and the selection signal for causing the drive circuit to select the selected waveform signal is output .
When the environmental temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature, or when the environmental temperature detected by the temperature detecting means is lower than the predetermined temperature and the total is calculated by the discharge amount calculating means. If the discharge amount is less than the specified amount
When the discharge amount defined by the discharge data is a discharge amount corresponding to any one or a plurality of waveform signal sets of the second waveform signal group, the standard waveform signal of the waveform signal set is driven. A liquid discharge device characterized in that a selection signal for making a circuit select is output . The head has a common flow path through which the plurality of pressure chambers communicate in common.
The plurality of actuators are divided into a plurality of actuator groups.
The waveform signal generation circuit is
Using the plurality of types of waveform signals as one signal set, a plurality of signal sets corresponding to each of the plurality of actuator groups are generated and output to the drive circuit.
The drive circuit
For each of the actuators belonging to each of the actuator groups, the drive having a drive waveform corresponding to the waveform of the waveform signal selected according to the selection signal from the plurality of types of waveform signals of the corresponding signal set. Output the signal,
The liquid discharge device according to claim 1, wherein the phases of the first drive pulses in the plurality of types of waveform signals belonging to the signal set are different from each other among the different signal sets. Among the different signal sets, the waveform signals classified into the second waveform signal group among the plurality of types of waveform signals belonging to the signal set are characterized in that the transition times do not overlap each other. The liquid discharge device according to claim 2. Further, a transport unit for transporting the medium in a predetermined transport direction with respect to the head is provided.
The head discharges liquid from the plurality of discharge ports to a medium transported in the transport direction by the transport unit.
The plurality of discharge ports are arranged in an arrangement direction that is parallel to the transport surface of the medium and intersects the transport direction, and constitutes a plurality of discharge port rows that are lined up in the transport direction.
The liquid discharge device according to claim 2 or 3, wherein the plurality of actuators corresponding to the plurality of discharge ports belonging to the same discharge port row belong to the same actuator group. The plurality of types of waveform signals are
One non-discharge waveform signal having zero number of drive pulses, one small drop discharge waveform signal, and one medium drop discharge waveform signal classified into the first waveform signal group.
The liquid according to any one of claims 1 to 4, wherein the liquid is composed of a plurality of large-drop ejection waveform signals belonging to the same waveform signal set, which are classified into the second waveform signal group. Discharge device. A storage unit for storing an allocation table in which allocation of each of the plurality of actuators to any of a plurality of waveform signals belonging to the waveform signal set is specified for each waveform signal set is further provided.
The selection circuit
When the selection signal for each actuator is output to the drive circuit,
When the discharge amount defined by the discharge data is a discharge amount corresponding to any one or a plurality of waveform signal sets of the second waveform signal group, the waveform signal is referred to by referring to the allocation table. Claims 1 to 1, wherein a waveform signal assigned to the actuator is selected from a plurality of waveform signals belonging to the set, and a selection signal for causing the drive circuit to select the selected waveform signal is output. 5. The liquid discharge device according to any one of 5.