JP2022085158A - Ejection adjustment method for head - Google Patents

Abstract

To provide an ejection adjustment method for suppressing nonuniform density between head chips by suppressing an increase in luminance between head chips, in a printing device provided with a head having the plurality of head chips.SOLUTION: A predetermined test pattern is optically read to obtain first scan data corresponding to a read range and second scan data corresponding to a read range. Based on the first scan data, luminance data D1 of each of channels corresponding to the positions of nozzles in the read range is acquired. Based on the second scan data, luminance data D2 of each of channels corresponding to the positions of nozzles in the read range is acquired. Based on whether a difference Δ between the luminance data D1 and the luminance data D2 is within a predetermined range or not, a determination is made which one of the luminance data should be selected; and based on the selected one of the luminance data, allocation of five power circuits 21 to 25 in a line head is selected.SELECTED DRAWING: Figure 9

Description

The present invention relates to a discharge adjusting method for a head including a plurality of power supply circuits and a plurality of head chips.

In recent years, there has been an increasing demand for printing devices having large line heads. As a technique for forming a large line head, it is known that a plurality of head chips are arranged in a staggered pattern along the longitudinal direction of the line head (see Patent Document 1).

Japanese Patent No. 6669175

In a line head having a plurality of head chips arranged in the longitudinal direction as described above, two head chips adjacent to each other in the longitudinal direction are arranged so as to partially overlap each other in the longitudinal direction. In this case, the luminance of the image formed by the nozzles in the region of each head chip that does not overlap with the other head chips in the longitudinal direction (non-overlapping region) is higher than the brightness of the image that overlaps with the other head chips in the longitudinal direction (overlap). A phenomenon (called an edge rise in brightness) is observed in which the brightness of the image formed by the nozzles in the region) is higher. If there is such a rise in brightness, density unevenness occurs between the two head chips, which adversely affects the image quality.

INDUSTRIAL APPLICABILITY In the present invention, in a printing apparatus provided with a head such as a line head having a plurality of head chips, the ejection for suppressing the edge rise of the luminance between the head chips and suppressing the density unevenness between the two head chips. The purpose is to provide an adjustment method.

According to the aspect of the present invention, it is a discharge adjustment method of a head including a plurality of power supply circuits and a plurality of head chips.
The first luminance data regarding the luminance of the pattern is calculated based on the first scan data obtained by optically reading a predetermined pattern printed by the plurality of head chips of the head over the first reading range. To do and
The pattern is related to the luminance of the pattern based on the second scan data which includes the first reading range and is optically read over a second reading range wider than the first reading range. Calculating the second luminance data and
The luminance of either the first luminance data or the second luminance data is based on whether or not the difference between the first luminance data and the second luminance data is within a predetermined range. Selecting data and
To select the allocation of the plurality of power circuits in one of the head chips of the head based on the selected luminance data of one of the heads.
A discharge adjusting method for a head comprising the above is provided.

According to the aspect of the present invention, it is possible to suppress the occurrence of the edge rise of the luminance among the plurality of head chips and suppress the density unevenness between the plurality of head chips.

It is a top view which shows an example of the main part structure of the printer 1 of this embodiment. It is a bottom view which shows an example of the head tip 11 of this embodiment. It is a block diagram which shows an example of the structure of the 2nd board 50 provided in the head chip 11 of this embodiment, and the flexible circuit board 60 connected to the 2nd board 50. It is a figure which shows an example of the circuit structure which a driver IC 27 has. It is a circuit diagram which shows an example of the structure of the waveform generation circuit 30 provided in the driver IC 27. It is explanatory drawing which shows the test pattern TP and the histogram H1. It is explanatory drawing which shows the test pattern TP and the histogram H2. It is explanatory drawing for demonstrating four approximate curves (L1 to L4). It is a flowchart for demonstrating the ejection adjustment method of the head which concerns on 1st Embodiment. It is a part of the flowchart for explaining the discharge adjustment method of the head which concerns on 2nd Embodiment. It is a part of the flowchart for explaining the discharge adjustment method of the head which concerns on 2nd Embodiment.

<First Embodiment>
Hereinafter, the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 9.

In FIG. 1, the transport direction of the sheet S (recording medium) corresponds to the front-back direction of the printer 1. Specifically, the downstream side in the transport direction corresponds to the front, and the upstream side in the transport direction corresponds to the rear. Further, the width direction of the sheet S is a direction parallel to the surface on which the sheet S is conveyed (a surface parallel to the paper surface in FIG. 1) and orthogonal to the conveying direction, and corresponds to the left-right direction of the printer 1. .. As shown in FIG. 1, the left side when the printer 1 is viewed from the front is the left side of the printer 1, and the right side of FIG. 1 is the right side of the printer 1. Further, the direction orthogonal to the transport surface of the sheet S (the direction orthogonal to the paper surface of FIG. 1) is defined as the vertical direction of the printer 1. In FIG. 1, the front side of the paper surface is the upper side, and the back side of the paper surface is the lower side. In the following, the front-back direction, the left-right direction, and the up-down direction will be described as appropriate.

As shown in FIG. 1, the printer 1 mainly includes a housing 2, a platen 3, four line heads 4, two transport rollers 5A and 5B, and a controller 7.

The platen 3 is arranged inside the housing 2. A sheet S is placed on the upper surface of the platen 3. The four line heads 4 are arranged above the platen 3 so as to be arranged in the front-rear direction. The two transport rollers 5A and 5B are arranged on the rear side and the front side of the platen 3 so as to sandwich the platen 3 in the front-rear direction. The two transport rollers 5A and 5B are driven by motors (not shown), respectively, and transport the sheet S on the platen 3 forward (downstream in the transport direction).

As shown in FIG. 3, the controller 7 includes a first substrate 71. The first substrate 71 includes an FPGA (Field Programmable Gate Array) 711, a ROM (Read Only Memory) (not shown), a RAM (Random Access Memory) (not shown), an EEPROM (Electrically Elementary Memory), an EEPROM (Electrically Memory), etc. The controller 7 can communicate with an external device 9 such as a personal computer or a smartphone. The controller 7 controls the operation of each line head 4 and the transfer rollers 5A and 5B according to a program stored in the ROM according to an instruction from an operation unit (not shown) provided in the external device 9 or the printer 1. A CPU (Central Processing Unit) or an MPU (Microprocessor Unit) may be used in place of the FPGA 711 or in addition to the FPGA 711.

For example, the controller 7 controls the motor that drives the transport rollers 5A and 5B, and causes the transport rollers 5A and 5B to transport the seat S forward. Further, the controller 7 controls each line head 4 to eject ink toward the sheet S. As a result, the image is printed on the sheet S. The sheet S may be a roll-shaped sheet including a supply roll including an upstream end in the transport direction and a recovery roll including the downstream end in the transport direction. In this case, the supply roll may be attached to the transport roller 5A on the upstream side in the transport direction, and the recovery roll may be attached to the transport roller 5B on the downstream side in the transport direction. Alternatively, the sheet S may be a roll-shaped sheet containing only the supply roll including the upstream end in the transport direction. In this case, the supply roll may be attached to the transport roller 5A on the upstream side in the transport direction.

As shown in FIG. 1, four head holding portions 8 are attached to the housing 2 corresponding to the four line heads 4. The four head holding portions 8 are arranged side by side above the platen 3 and at positions between the transport rollers 5A and 5B in the front-rear direction. One line head 4 is held by each head holding portion 8.

Each of the four line heads 4 ejects four colors of ink, cyan (C), magenta (M), yellow (Y), and black (K). Ink of the corresponding color is supplied to each line head 4 from an ink tank (not shown).

As shown in FIG. 1, each line head 4 of the present embodiment includes 10 head chips 11. The 10 head tips 11 are arranged in two rows in a staggered manner along the left-right direction. Since one color of ink is supplied to one line head 4, the one color of ink is ejected from the ten head chips 11 included in the one line head 4.

As shown in FIG. 2, a plurality of nozzles 11a are opened on the bottom surface of each head chip 11 of the present embodiment. In the present embodiment, each head tip 11 has 1680 nozzles 11a, but in FIG. 2, only a part of the nozzles 11a is shown for easy viewing of the drawings. The nozzles 11a form four nozzle rows r1 to r4 arranged in the front-rear direction. The nozzles 11a included in the nozzle rows r1 to r4 are arranged at a predetermined pitch P so as to extend in the left-right direction. The four nozzle rows r1 to r4 are arranged so as to be displaced by P / 4 from each other in the left-right direction. Two manifolds (not shown) are formed in each head chip 11, and ink is supplied to the nozzles 11a constituting the nozzle rows r1 and r2 from one of the manifolds. Ink is supplied from the other manifold to the nozzles 11a constituting the nozzle rows r3 and r4. The position of each nozzle 11a in each head chip 11 is uniquely specified by the nozzle row to which the nozzle 11a belongs and the position in the transport direction.

Further, each head chip 11 is provided with a second substrate 50 (see FIG. 3), a flexible circuit board 60 (see FIG. 3), and the same number of drive elements 111 (see FIG. 5) as the nozzles 11a. Since the printer 1 of the present embodiment includes four line heads 4, and each line head 4 includes ten head chips 11, the printer 1 includes 40 head chips 11. Therefore, the number of the second substrate 50 is also 40, and the number of the flexible circuit boards 60 connected to the second substrate 50 is also 40. As shown in FIG. 3, the first board 71 of the controller 7 is connected to 40 second boards 50. Note that FIG. 3 shows only one second substrate 50 and one flexible circuit board 60 for convenience.

As shown in FIG. 3, the second substrate 50 includes a non-volatile memory 52 such as FPGA 51 and EEPROM, a D / A converter 20, and power supply circuits 21 to 26. The flexible circuit board 60 includes a non-volatile memory 62 such as EEPROM and a driver IC 27.

The FPGA 51 outputs a digital setting signal for setting the output voltage of the power supply circuits 21 to 26 to the D / A converter 20 under the control of the FPGA 711 provided on the first substrate 71.

The D / A converter 20 converts the digital setting signal output by the FPGA 51 into an analog setting signal and outputs it to the power supply circuits 21 to 26.

As the power supply circuits 21 to 26, for example, a DC / DC converter composed of a plurality of electronic components such as FETs, inductors, resistors, and electrolytic capacitors can be used. Each power supply circuit 21 to 26 outputs the output voltage specified by the set signal to the driver IC 27. In the present embodiment, the power supply circuits 21 to 26 are all set so that the output voltages are different. In this embodiment, the output voltage of the power supply circuit 21 is 22V, the output voltage of the power supply circuit 22 is 21V, the output voltage of the power supply circuit 23 is 20V, the output voltage of the power supply circuit 24 is 19V, and the output voltage of the power supply circuit 25 is 18V. And the output voltage of the power supply circuit 26 is 24V.

The driver IC 27 is connected to the power supply circuit 21 via the wiring VDD1, is connected to the power supply circuit 22 via the wiring VDD2, is connected to the power supply circuit 23 via the wiring VDD3, and is connected to the power supply circuit 24 via the wiring VDD4. It is connected to the power supply circuit 25 via the wiring VDD5, and is connected to the power supply circuit 26 via the wiring H VDD. The power supply circuit 26 is connected to the drive element 111, which will be described later, via a wiring VCOM. In the wiring H VDD and the wiring VCOM, the wiring drawn from the power supply circuit 26 is branched into two wirings in the middle of the route.

The power supply circuits 21 to 26 are a waveform generation circuit 30 (1) to a waveform generation circuit 30 (n) (n is a natural number of 2 or more) formed inside the driver IC 27 via the wirings VDD1 to VDD5 and the wiring H VDD. In this embodiment, it is connected to (equal to the number of drive elements 111 included in the head chip 11) (see FIG. 4).

The waveform generation circuits 30 (1) to 30 (n) are provided corresponding to the n drive elements 111 included in each head chip 11. That is, the waveform generation circuits 30 (1) to 30 (n) are provided corresponding to the n nozzles 11a provided in each head chip 11. The driver IC 27 is connected to n signal lines 34 (1) to 34 (n). The driver IC 27 is connected to n drive elements 111 via n signal lines 34 (1) to 34 (n). Each signal line 34 is connected to an individual electrode of the drive element 111.

Further, as shown in FIG. 4, the driver IC 27 includes n selectors 90 (1) to 90 (n) provided corresponding to the n drive elements 111. Each selector 90 is a hardware component composed of a plurality of FETs and the like formed inside the driver IC 27.

The power supply circuit 26 can be used as the VCOM power supply voltage of the drive element 111 or as the H VDD (high side backgate voltage) of the polyclonal transistors 311 to 315 described later.

As shown in FIG. 3, the driver IC 27 is connected to the FPGA 51 via n control lines 33 (1) to 33 (n) and a control line 40. The control lines 33 (1) to 33 (n) are control lines provided corresponding to the above-mentioned n waveform generation circuits 30 (1) to 30 (n). A signal for controlling the FET provided in each waveform generation circuit 30 is propagated to each control line 33. According to this signal, the waveform generation circuit 30 generates a drive signal for driving the drive element 111, and outputs the generated drive signal to the drive element 111 via the signal line 34.

Further, a control signal for controlling the n selectors 90 (1) to 90 (n) of the driver IC 27 is transmitted to the control line 40. The FPGA 51 selects a power supply circuit for generating a drive signal to be output to each signal line 34 by controlling n selectors 90 (1) to 90 (n).

Next, an example of the circuit configuration included in the driver IC 27 will be described with reference to FIG. As shown in FIG. 4, the driver IC 27 is provided corresponding to n waveform generation circuits 30 (1) to 30 (n) and waveform generation circuits 30 (1) to 30 (n), respectively. The selector 90 (1) to 90 (n) is provided.

Since the driver IC 27 has the same configuration as n nozzles, the circuit configuration provided below is typically provided between the control line 33 (1) and the signal line 34 (1). Will be explained. In the driver IC 27, a selector 90 (1) and a waveform generation circuit 30 (1) are formed between the control line 33 (1) and the signal line 34 (1).

The control line 33 (1) from the FPGA 51 is connected to the selector 90 (1). The control line 33 (1) is branched in the middle of the path connecting the FPGA 51 and the selector 90 (1), and the control line SB (1) branched from the control line 33 (1) is connected to the waveform generation circuit 30 (1). It is connected.

The selector 90 (1) and the waveform generation circuit 30 (1) are connected by five control lines S1 (1), S2 (1), S3 (1), S4 (1), and S5 (1). There is. The selector 90 (1) is selected from the five control lines S1 (1), S2 (1), S3 (1), S4 (1), and S5 (1) according to the instruction from the FPGA 51. One control line is connected to the control line 33 (1).

In the waveform generation circuit 30 (1), five wirings connected to the above-mentioned wirings VDD1 to VDD5, a wiring connected to the wiring H VDD, and a wiring connected to the wiring GND are connected.

Next, an example of the configuration of the waveform generation circuits 30 (1) to 30 (n) included in the head chip 11 of the present embodiment will be described with reference to FIG. Since the waveform generation circuits 30 (1) to 30 (n) have the same configuration, the waveform generation circuit 30 (1) will be described below. The waveform generation circuit 30 (1) has five polyclonal (P-type Metal Oxide Semiconductor) transistors 311 to 315 (only two are shown in FIG. 5), and one IGMP (N-type Metal Oxide Semiconductor) transistor 32. , Resistance 35 and the like. The waveform generation circuit 30 (1) is connected to the individual electrodes of the drive element 111 via the signal line 34 (1).

The drive element 111 of the present embodiment has, for one pressure chamber, between the first active portion sandwiched between the individual electrode and the first constant potential electrode, and between the individual electrode and the second constant potential electrode. It is a piezoelectric element provided with a second active portion sandwiched between the two. Therefore, the drive element 111 includes a capacitor 111b and a capacitor 111b'.

Wiring VDD1 to VDD5 are connected to the five source terminals 311a to 315a of the five polyclonal transistors 311 to 315, respectively. The source terminal 32a of the MIMO transistor 32 is connected to the ground. That is, the polyclonal transistor 311 is connected to the power supply circuit 21 via the wiring VDD1. The polyclonal transistor 312 is connected to the power supply circuit 22 via the wiring VDD2. The polyclonal transistor 313 is connected to the power supply circuit 23 via the wiring VDD3. The polyclonal transistor 314 is connected to the power supply circuit 24 via the wiring VDD4. The polyclonal transistor 315 is connected to the power supply circuit 25 via the wiring VDD5.

A control line S1 (1) is connected to the gate terminal 311c of the polyclonal transistor 311. A control line S2 (1) is connected to the gate terminal 312c of the polyclonal transistor 312. A control line S3 (1) is connected to the gate terminal 313c of the polyclonal transistor 313. A control line S4 (1) is connected to the gate terminal 314c of the polyclonal transistor 314. A control line S5 (1) is connected to the gate terminal 315c of the polyclonal transistor 315. Further, a control line SB (1) is connected to the gate terminal 32c of the MIMO transistor 32.

Further, the drain terminals 311b to 315b of the five polyclonal transistors 311 to 315 are connected to one end of the resistor 35. Further, the drain terminal 32b of the NaOH transistor 32 is connected to one end of the resistor 35. The other end of the resistor 35 is connected to an individual electrode of the drive element 111 (the other end of the capacitor 111b'and one end of the capacitor 111b). The first constant potential electrode (one end of the capacitor 111b') of the drive element 111 is connected to the VCOM, and the second constant potential electrode (the other end of the capacitor 111b) of the drive element 111 is connected to the ground.

When the FPGA 51 outputs a low level (“L”) signal to the control line 33 (1), any one of the polyclonal transistors 311 to 315 connected to the signal line selected by the selector 90 (1) described above. One polyclonal transistor is turned on. The capacitor 111b is charged by the voltage supplied from any one of the power supply circuits 21 to 25, and the capacitor 111b'is discharged. On the other hand, when the FPGA 51 outputs a high level (“H”) signal to the control line 33 (1), the nanotube transistor 32 is turned on and the voltage output from any one of the power supply circuits 21 to 25. Charges the capacitor 111b'and discharges the capacitor 111b. By alternately charging and discharging the capacitors 111b and 111b', the driving element 111 is deformed and ink is discharged from the ejection port 11a of the nozzle.

That is, a drive signal for driving the drive element 111 is output to the signal line 34 (1). The power supply circuit that generates a drive signal by selecting one control line to be connected from the five control lines S1 (1) to S5 (1) by the selector 90 (1) is included in the power supply circuits 21 to 25. You can choose from. As described above, the controller 7 controls the selector 90 of the FPGA 51 and the driver IC 27 via the FPGA 711, so that the drive signal is used for each drive element 111 by using any of the power supply circuits 21 to 25. You can choose whether to generate. In other words, the controller 7 can adjust the voltage of the drive signal that drives each drive element 111.

Next, the increase in brightness in the printer 1 of the present embodiment will be described. FIG. 6 shows a test pattern TP printed using the printer 1 of the present embodiment and a histogram H1 of a luminance distribution obtained by scanning the reading range AR1 of the test pattern TP with a scanner. FIG. 7 shows a histogram H2 of the luminance distribution obtained by scanning the reading range AR2 of the same test pattern TP with a scanner.

The test pattern TP has four patterns of the same shape corresponding to the four line heads 4, with cyan (C), magenta (M), yellow (Y), and black (K) inks, respectively. It is formed. In addition, in FIGS. 6 and 7, a part of the pattern formed by the ink of cyan (C) and magenta (M) is shown.

The reading range AR1 shown in FIG. 6 is a region formed by 1680 nozzles 11a included in a certain head chip 11. Although only one reading range AR1 is shown in FIG. 6, the reading range AR1 is set for each of the ten rectangular patterns corresponding to the ten head chips 11. In the histogram H1 of FIG. 6, 1ch each corresponds to one nozzle, and the reading range AR1 corresponds to 1680ch (141ch to 1820ch). As described above, the ten head chips 11 are arranged in a staggered manner in the left-right direction, and both ends of each head chip 11 in the left-right direction overlap with the head chips 11 adjacent to each other in the left-right direction in the front-rear direction. Correspondingly, both ends of the reading range AR1 correspond to the nozzles 11a of the nozzles 11a of a certain head chip 11 at positions overlapping with the adjacent head chips 11 in the front-rear direction.

The reading range AR2 shown in FIG. 7 is a region obtained by extending the reading range AR1 in the left-right direction. The regions outside the reading range AR1 at both ends of the reading range AR2 in the left-right direction are formed by the nozzles 11a included in another head chip 11 adjacent in the left-right direction. Although only one reading range AR2 is shown in FIG. 7, the reading range AR2 is set for each of the 10 rectangular patterns corresponding to the 10 head chips 11. In the present embodiment, the reading range AR2 is formed by 1680 nozzles 11a included in one head chip 11 and 280 nozzles 11a included in the head chips 11 adjacent to the head chip 11 in the left-right direction. There is. In the histogram H2 of FIG. 7, the reading range AR2 corresponds to 1960ch (1ch to 1960ch).

From the histogram H1 in FIG. 6, it can be read that the luminance is increased at both ends in the left-right direction of the reading range AR1, that is, in the region overlapping with another head chip 11 adjacent in the left-right direction in the front-rear direction. If there is such an increase in brightness, uneven ink density may occur between two head chips 11 adjacent to each other in the left-right direction, and print quality may be impaired. Therefore, in the present embodiment, the rise in brightness is suppressed by using the head ejection adjustment method described below.

The discharge adjustment method of the head for suppressing the edge rise of the luminance according to the present embodiment will be described with reference to the flowchart of FIG. First, the first scan data corresponding to the reading range AR1 and the reading range AR2 are obtained by optically reading the test pattern TP printed by the four line heads 4 of the printer 1 using a scanner (not shown). The second scan data corresponding to the above is acquired. Then, based on the first scan data and the second scan data, the luminance values of the reading range AR1 and the reading range AR2 for each channel corresponding to the position of the nozzle 11a are acquired. In the present embodiment, the test pattern TP has 40 reading ranges AR1 and 40 reading ranges AR2, corresponding to each of the four line heads 11 having 10 head chips 11. include.

For each of the 40 reading ranges AR1, the width of the moving section is set to 24 channels, the moving average of the luminance values of each channel is calculated, and the luminance data D1 is created (S100). Similarly, for each of the 40 reading ranges AR2, the width of the moving section is set to 96ch, the moving average of the luminance value of each channel is calculated, and the luminance data D2 is created (S101). In the following processing, the luminance data D1 and the luminance data D2 corresponding to a certain head chip 11 are treated as a set of data sets. For the 40 sets of the luminance data D1 and the luminance data D2, the allowable value d1 of the difference between the luminance data D1 and the luminance data D2 is set. In the present embodiment, the allowable value of the difference Δ between the luminance data D1 and the luminance data D2 is set to ± 1 for all the pairs of the luminance data D1 and the luminance data D2 (S102).

Next, the difference Δ is calculated for the set of luminance data D1 and the luminance data D2, and it is determined whether or not the difference Δ is within the permissible value (1 in the present embodiment) (S104). When the difference Δ is within the permissible value (S104: Yes), that is, when the absolute value of the difference Δ is less than 1, the luminance data D1 is selected (S105). Further, when the difference Δ is not within the allowable value (S104: No), that is, when the absolute value of the difference Δ is 1 or more, the luminance data D2 is selected (S106).

Next, four approximate curves are calculated based on the selected luminance data D1 or luminance data D2 (S107). In this embodiment, eight points are extracted by the following procedure, and four approximate curves (straight line approximation formulas) are calculated. The average a of 48ch to 96ch is set at the point a1 (72ch), and the average b of 120ch to 168ch is set at the point b1 (144ch). Then, the first approximate curve (Y = αX + β) is calculated from the points a1 and b1 (see the straight line L1 in FIG. 8). Similarly, the average c of 256ch to 304ch is set at the point c1 (280ch), and the average d of 816ch to 839ch is set at the point d1 (839ch). Then, the second approximate curve (Y = αX + β) is calculated from the points c1 and d1 (see the straight line L2 in FIG. 8). The average e of 840ch to 869ch is set at the point e1 (840ch), and the average f of 1376ch to 1424ch is set at the point f1 (1400ch). Then, the third approximate curve (Y = αX + β) is calculated from the points e1 and f1 (see the straight line L3 in FIG. 8). The average g of 1632ch to 1680ch is set at the point g1 (1656ch), and the average h of 1728ch to 1766ch is set at the point h1 (1752ch). Then, the fourth approximate curve (Y = αX + β) is calculated from the points g1 and h1 (see the straight line L4 in FIG. 8).

Next, the difference between the selected luminance data D1 or luminance data D2 and the approximate curve is calculated (S108). For example, when the luminance data D2 is selected, the difference between the luminance data D2 and the approximate curve is calculated in the range of 72ch to 144ch, 280ch to 839ch, 840ch to 1400ch, and 1656ch to 1752ch (S108). Then, based on the calculated difference, the power supply circuit for driving the drive element 111 used for ejecting ink is selected from the power supply circuits 21 to 25 for the nozzles 11a corresponding to each channel in these ranges. (S109). For example, in order to bring the brightness data D2 closer to the approximate curve in a certain channel, it is better to lower the drive voltage for driving the drive element 111 used for ejecting ink from the nozzle 11a corresponding to the channel. If it is determined, the power supply circuit is selected from the power supply circuits 21 to 25 so that the output voltage value is low. On the contrary, in order to bring the brightness data D2 closer to the approximate curve in a certain channel, it is better to increase the drive voltage for driving the drive element 111 used for ejecting ink from the nozzle 11a corresponding to the channel. If it is determined that, the power supply circuit is selected from the power supply circuits 21 to 25 so that the output voltage value becomes high. In the above-mentioned channel range, when the selection of the power supply circuit is completed for all channels, it is determined whether or not there is a pair of unprocessed luminance data D1 and luminance data D2 (S103), and the unprocessed luminance data D1 and If there is a set of luminance data D2 (S103: Yes), the above-mentioned processes S104 to S109 are repeated. If there is no pair of unprocessed luminance data D1 and luminance data D2 (S103: No), the processing is terminated.

<Effect of the first embodiment>
In the above embodiment, a scanner (not shown) optically reads a predetermined test pattern TP printed by using the line head 4, and corresponds to the first scan data corresponding to the reading range AR1 and the reading range AR2. The second scan data is acquired. Since the reading range AR2 is a region obtained by extending the reading range AR1 in the left-right direction, the reading range AR1 is included and is wider than the reading range AR1. Then, based on the first scan data, the luminance data D1 for each channel corresponding to the position of the nozzle 11a in the reading range AR1 is acquired. Further, based on the second scan data, the luminance data D2 for each channel corresponding to the position of the nozzle 11a in the reading range AR2 is acquired. Then, it is determined which luminance data to select based on whether the difference Δ between the luminance data D1 and the luminance data D2 is within a predetermined range. Further, the allocation of the five power supply circuits 21 to 25 in the line head 4 is selected based on the one selected luminance data.

In the present embodiment, when the difference Δ between the luminance data D1 and the luminance data D2 is within a predetermined range (within the range of ± 1), the luminance data D1 having a small number of channels is selected. As a result, the load of calculation such as when calculating the moving average can be reduced. When the difference Δ between the luminance data D1 and the luminance data D2 exceeds a predetermined range (± 1 range), the luminance data D2 having a large number of channels is selected. This makes it possible to improve the accuracy of calculations such as when calculating a moving average. Further, in the present embodiment, it is determined that it is better to lower the drive voltage for driving the drive element 111 used when ejecting ink from the nozzle 11a corresponding to a certain channel, based on the selected luminance data. If so, the power supply circuit is selected so that the output voltage value is low among the power supply circuits 21 to 25. On the contrary, when it is determined that it is better to increase the drive voltage for driving the drive element 111 used for ejecting ink from the nozzle 11a corresponding to a certain channel, among the power supply circuits 21 to 25, The power supply circuit is selected so that the output voltage value is high. As a result, it is possible to suppress uneven ink density such as an increase in luminance that occurs when printing is performed by the line head 4.

In the present embodiment, the luminance data D1 is created by taking a moving average of the luminance values of each channel included in the reading range AR1 included in the first scan data in the moving section of 24 channels. Similarly, the luminance data D2 is created by taking a moving average of the luminance values of each channel included in the reading range AR2 included in the second scan data in the moving section of 96 channels. In this way, instead of using the luminance values included in the first and second scan data as they are, by taking a moving average, the luminance values of the channels whose luminance values are accidentally increased or decreased are smoothed. Can be done. Thereby, the reliability of the luminance data D1 and D2 can be improved.

In the present embodiment, when selecting the allocation of the power supply circuits 21 to 25 based on the selected luminance data D1 or luminance data D2, four approximate curves (approximate equations of four straight lines) are calculated and combined with the approximate curve. The difference from the selected luminance data is calculated. Then, the allocation of the power supply circuits 21 to 25 is selected based on the difference between the approximate curve and the selected luminance data. When the brightness is excessively high, such as when the brightness is rising, it is preferable to set the drive voltage low so as to lower the brightness. In the present embodiment, it is possible to easily obtain an index as to how much the drive voltage should be lowered.

In the present embodiment, as shown in FIG. 8, it can be confirmed that the brightness rises in the regions of 72ch to 144ch and 1656ch to 1752ch. The region where such an increase in brightness occurs corresponds to a region of two head chips 11 adjacent to each other in the left-right direction, which overlap each other in the front-rear direction. Then, in the present embodiment, the approximate expression of the straight line is calculated based on the average of about 50 channels sandwiching the point a1 (72ch) and the average of about 50 channels sandwiching the point b1 (144ch). Similarly, the approximate expression of the straight line is calculated based on the average of about 50 channels sandwiching the point g1 (1656 ch) and the average of about 50 channels sandwiching the point h1 (1752 ch). As described above, in the present embodiment, an approximate curve (approximate formula for a straight line) is calculated based on the brightness data for about 100 channels in the region where the two head tips 11 adjacent to each other in the left-right direction overlap each other in the front-rear direction. Therefore, the approximate curve can surely cover the region where the edge rise of the brightness occurs. By calculating an approximate curve (approximate formula for a straight line) based on the brightness data of 100 channels or more in the region where the two head chips 11 adjacent to each other in the left-right direction overlap each other in the front-rear direction, the approximate curve and the brightness data can be obtained. It is possible to increase the reliability of data processing when taking differences.

<Second Embodiment>
Next, the second embodiment of the present disclosure will be described with reference to FIGS. 10 and 11. For the configuration common to the first embodiment, the same reference numerals are used and detailed description thereof will be omitted.

Also in this embodiment, a scanner (not shown) optically reads the test pattern TP printed by using the four line heads 4 of the printer 1, and obtains the first scan data corresponding to the reading range AR1 and the reading range AR2. The second scan data corresponding to the above is acquired. The variation in the luminance values in the first scan data and the second scan data is determined, and the number of approximate curves is determined (S200). In this embodiment, a straight line is adopted as the approximate curve, and when the variation of the brightness value in the first scan data and the second scan data exceeds a predetermined threshold value, the number of approximate curves (straight lines) is four. Has been increased to 6 from. Subsequent processing of S100 to S107 is the same as that of the first embodiment, and thus the description thereof will be omitted. However, the process of S107 takes as an example the case where eight-point extraction is performed as in the first embodiment, but when it is decided in the above-mentioned process S200 that the number of approximate curves is six, the process is S107. Further, four points are extracted, and an approximate expression of six approximate curves (straight lines) is calculated.

Following the processing of S107, the average k for 100 channels before and after the point b1 (144ch) is calculated, and the difference x from the average b of 120ch to 168ch is calculated (S201). Then, the average i for 100 channels before and after the point f1 (1400 ch) is calculated, and the difference y from the average f of 1376 ch to 1424 ch is calculated (S202). Next, when the difference x exceeds a predetermined threshold value (1 in the present embodiment) (S203: Yes), the average k of 100 channels before and after the point b1 (144ch) is set at the point b1 (S205). When the difference y exceeds a predetermined threshold value (1 in the present embodiment) (S204: Yes), the average i of 100 channels before and after the point f1 (1400 ch) is set at the point f1 (S206). Then, in the processing of S205 and S206, when at least one of the average values set at the points b1 and f1 is changed, the approximate curve created in the processing S107 is set in the processing of S205 and S206. Correct using the averages k and i (S207). Since the subsequent processing of S108 and S109 is the same as that of the first embodiment, the description thereof will be omitted.

In the present embodiment, it is determined whether or not the variation in the luminance values in the first scan data and the second scan data exceeds a predetermined threshold value. When the variation in the luminance values in the first scan data and the second scan data exceeds a predetermined threshold value, the number of approximate curves (straight lines) is increased from four to six. As a result, the drive voltage can be appropriately set so as to further suppress the variation in the luminance value.

In the present embodiment, the width of the section for calculating the average set at the points b1 and f1 is widened from about 50 ch to 100 ch. Then, the approximate curve is corrected based on the average luminance calculated by the expanded section. The area before and after the point b1 and the point f1 is a region where the luminance value is expected to vary greatly. Therefore, by calculating the average over a wider range, the influence of the variation in the luminance values before and after the points b1 and f1 can be suppressed, and the reliability of the approximate curve can be improved.

The embodiments described above are merely examples and may be changed as appropriate. In the above embodiment, the printer 1 includes four line heads 4, but the number of line heads 4 is not limited to four. Further, in the above embodiment, one line head 4 includes 10 head chips 11, but the number of head chips 11 is not limited to 10. Further, in the above-described embodiment, each head chip 11 includes 1680 nozzles 11a, but the number of nozzles 11a is not limited to 1680. Further, the number of nozzle rows is not limited to four. Further, the number of manifolds provided on each head chip 11 is not limited to two. For example, one manifold may be provided for each of the nozzle rows r1 to r4, or one manifold (that is, a total of four) may be provided for each of the nozzle rows r1 to r4. Further, in the above embodiment, the second substrate 50 includes six power supply circuits 21 to 26, but the number of power supply circuits is not limited to six. Further, the output voltage of each power supply circuit 21 to 26 can be changed as appropriate.

The shape of the test pattern TP is merely an example and can be changed as appropriate. Further, the widths of the reading ranges AR1 and AR2 can be appropriately changed as long as the reading range AR2 includes the reading range AR1.

In the above embodiment, the width of the moving section of the moving average is set to 24ch or 96ch, but the present disclosure is not limited to this and can be changed as appropriate. Further, in the above embodiment, a straight line is used as an approximate curve, but the present disclosure is not limited to this. For example, a curve such as a quadratic curve can be used as the approximate curve. In the above embodiment, eight points (points a1 to h1) were extracted in order to calculate the approximate curve of the straight line, but the positions and numbers of the extracted points in order to calculate the approximate curve can be appropriately changed. ..

In the above embodiment, the average of the luminance values over a predetermined number of channels is calculated around each of the points a1 to h1 and set as the luminance value of each point, but how many channels are around each point. Whether to average over minutes can be changed as appropriate.

In the above embodiment, the line head 4 is fixed to the printer 1 and the sheet S is conveyed, but the sheet S may be relatively moved with respect to the line head 4, for example, the fixed sheet S. The line head 4 may be configured to move with respect to the above.

1 Printer 4 Line head 5A, 5B Conveyor roller 7 Controller 11 Head chip 11a Nozzle 21-26 Power supply circuit 27 Driver IC
50 2nd board 51 FPGA
71 1st board 711 FPGA
712 EEPROM

Claims (6)

A discharge adjustment method for a head that includes multiple power supply circuits and multiple head chips.
The first luminance data regarding the luminance of the pattern is calculated based on the first scan data obtained by optically reading a predetermined pattern printed by the plurality of head chips of the head over the first reading range. To do and
The pattern is related to the luminance of the pattern based on the second scan data which includes the first reading range and is optically read over a second reading range wider than the first reading range. Calculating the second luminance data and
The luminance of either the first luminance data or the second luminance data is based on whether or not the difference between the first luminance data and the second luminance data is within a predetermined range. Selecting data and
To select the allocation of the plurality of power circuits in one of the head chips of the head based on the selected luminance data of one of the heads.
Head discharge adjustment method. The head tip includes a plurality of nozzles and contains a plurality of nozzles.
Acquiring the first luminance data is to calculate a first moving average value which is a value obtained by dividing the sum of the luminance values corresponding to the first number of nozzles by the first number in the first scan data. Including
Acquiring the second luminance data is a value obtained by dividing the sum of the luminance values corresponding to the second number of nozzles, which is larger than the first number, by the second number in the second scan data. Including calculating the moving average value
The discharge adjusting method for a head according to claim 1, wherein the allocation of the plurality of power supply circuits in one of the head chips of the head is selected based on the first moving average value or the second moving average value. Choosing the allocation of the plurality of power circuits in one of the head chips of the head based on the selected luminance data of one of the heads can be selected.
To calculate an approximate curve in a predetermined section of one of the luminance data,
To calculate the difference between the approximate curve and the luminance data of one of the predetermined sections in at least a part of the predetermined section.
The first or second aspect of claim 1 or 2, comprising selecting the allocation of the plurality of power circuits in one of the head chips of the head based on the difference between the approximation curve and the luminance data of one of the heads. Head discharge adjustment method. The plurality of head chips include a first head chip and a second head chip arranged so as to partially overlap the first head chip in the first direction.
The first and second head chips each include a plurality of nozzles arranged in the first direction and the plurality of power supply circuits.
The third aspect of claim 3 includes the area of the first head chip printed by 100 or more nozzles arranged in the first direction, including a portion of the first head chip that overlaps with the second head chip in the first direction. Head discharge adjustment method. Further, to acquire the magnitude of the variation of the luminance data of one of the above,
Determining whether the magnitude of the variation exceeds a predetermined value and
The discharge adjusting method for a head according to claim 3 or 4, wherein when it is determined that the magnitude of the variation exceeds the predetermined value, the number of the approximate curves is increased. Further, widening one width of the predetermined section corresponding to one of the approximate curves of the one luminance data.
The discharge adjusting method for a head according to claim 5, wherein one of the approximate curves is modified based on the widened predetermined section.

Images