JP2016132167A - Printer, control device and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase of a circuit area at the time when a nozzle array of a liquid discharge head is obliquely arranged with respect to a direction orthogonal to the conveyance direction of a printing medium.SOLUTION: A plurality of nozzles in a liquid discharge head are divided into a first nozzle group for discharging the first ink, a second nozzle group for discharging the second ink different from the first ink, and a blank nozzle group arranged between the first nozzle group and the second nozzle group. A first processing part 131 stores printing data corresponding to the first nozzle group, the blank nozzle group, and the second nozzle group in a third region of a DRAM 110. A second processing part 132 stores the printing data stored in the third region in an SRAM 112 in the order according to the arrangement of the nozzles. A third processing part 133 reads the printing data stored the SRAM 112 and supplies it to the liquid discharge head so as to make the liquid discharge head discharge the ink.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a printing apparatus, a control apparatus for the printing apparatus, and a control method.

  As a printing apparatus that prints an image or a document by discharging a liquid such as ink, a printer using a piezoelectric element (for example, a piezo element) or a heating element is known. Piezoelectric elements and heating elements are provided corresponding to each of the plurality of nozzles in the print head, and each is driven according to a drive signal, thereby ejecting a predetermined amount of ink from the nozzles at a predetermined timing, Thereby, dots are formed.

The following techniques are known as techniques applied to such a printing apparatus.
For example, in a configuration in which it is possible to select whether the print source data is extracted, processed into print data, and output as a PRN file, the generated PRN file is deleted when the processing cannot be completed normally Technology (for example, see Patent Document 1), technology for executing print processing when a print command is issued during timer cleaning, and normal print processing in the same processing time (for example, see Patent Document 2), printing A technique for preventing a white line in the main scanning direction from appearing in the result (for example, see Patent Document 3) is known.
By the way, in a printing apparatus, for example, a technique is known in which nozzle rows of a print head are arranged obliquely with respect to a direction orthogonal to a print medium conveyance direction (see Patent Document 4).

JP 2008-250435 A JP 2008-246942 A JP 2008-250799 A JP 2002-103597 A

In such a configuration in which the nozzle rows are arranged obliquely, the circuit in the printing apparatus is significantly more complicated than the configuration in which the nozzle rows are arranged in a direction orthogonal to the transport direction, resulting in an increase in cost. is assumed.
Accordingly, one of the objects of some aspects of the present invention is to prevent problems when the nozzle rows of the print head are arranged obliquely with respect to the direction perpendicular to the conveyance direction of the print medium, in particular, increase in circuit area. It is to solve the cost increase.

  In order to achieve one of the above objects, a printing apparatus according to one embodiment of the present invention is configured such that a relative movement direction between a print medium and a print head having a plurality of nozzles and an arrangement direction of the plurality of nozzles are not. The plurality of nozzles intersect at an orthogonal and non-parallel angle, and the plurality of nozzles includes a first nozzle group that ejects a first ink, a second nozzle group that ejects a second ink different from the first ink, and the first nozzle. A printing apparatus that is divided into a blank nozzle group disposed between the first nozzle group, the second nozzle group, and print data corresponding to the first nozzle group, the blank nozzle group, and the second nozzle group. A first processing unit to be stored in the first storage unit, a second processing unit to store the print data stored in the first storage unit in the second storage unit in an order according to the arrangement of the nozzles, and the first 2 Based on the print data stored in the storage unit A third processing unit for respectively ejecting ink, characterized in that it comprises a.

According to the printing apparatus according to the above aspect, since the second storage unit is shared by different colors,
Specifically, since the print data corresponding to the first nozzle group for ejecting the first ink and the print data corresponding to the second nozzle group for ejecting the second ink are shared, the storage unit is individually provided for each color. Compared with a configuration in which the storage unit is prepared, the capacity required for the storage unit can be reduced. For this reason, an increase in circuit area can be prevented and an increase in cost can be suppressed.

In the one aspect, a dummy nozzle group is provided at a front end or a rear end of a nozzle row of the first nozzle group, the blank nozzle group, and the second nozzle group, and the third processing unit is configured to store the first memory. The data may be added to the dummy nozzle group at the front end or rear end of the print data stored in the section. According to this configuration, it is possible to avoid storing data corresponding to the dummy nozzle group in the second storage unit.
The present invention can be realized in various modes, and can be conceptualized as, for example, a control device or a control method of a printing apparatus.

1 is a diagram illustrating a schematic configuration of a printing apparatus according to an embodiment. It is a top view of the liquid discharge module in a printing apparatus. It is a figure which shows the nozzle arrangement of the liquid discharge head in a liquid discharge module. It is a figure which shows the positional relationship of the nozzle in a liquid discharge head. It is a fragmentary sectional view of a liquid discharge head. It is explanatory drawing of the dot formed by the ink discharge of a liquid discharge head. FIG. 3 is a block diagram illustrating an electrical configuration of the printing apparatus. It is a block diagram which shows the structure of the control part in a printing apparatus. It is a figure for demonstrating an array conversion process. It is a figure which shows the data etc. which are stored in SRAM. It is a figure which shows the data etc. which are stored in SRAM. It is a figure for demonstrating the case of a straight head.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a partial configuration of a printing apparatus 1 according to the embodiment.
The printing apparatus 1 ejects ink (liquid) to form a group of ink dots on a print medium P such as paper, thereby printing an image (including characters, graphics, etc.) according to the image data. Printing apparatus (inkjet printer).

  As shown in the drawing, the printing apparatus 1 includes a control unit 10, a transport mechanism 12, and a liquid ejection module 20. In addition, the printing apparatus 1 is equipped with a liquid container (cartridge) 14 that stores a plurality of colors of ink. In this example, a total of four ink colors, cyan (C), magenta (M), yellow (Y), and black (Bk), are stored in the liquid container 14.

  The control unit 10 processes an image supplied from an external host computer and controls each element of the printing apparatus 1 as will be described later. The transport mechanism 12 transports the print medium P in the Y direction under the control of the control unit 10. The liquid ejection module 20 ejects the ink stored in the liquid container 14 onto the print medium P under the control of the control unit 10. In the embodiment, the liquid ejection module 20 is a line head that is long in the X direction that intersects (typically orthogonal) in the Y direction.

In the printing apparatus 1, the liquid ejection module 20 ejects ink onto the print medium P in synchronization with the transport of the print medium P by the transport mechanism 12, thereby forming an image on the surface of the print medium P.
A direction perpendicular to the XY plane (a plane parallel to the surface of the print medium P) is hereinafter referred to as a Z direction. The Z direction is typically an ink ejection direction by the liquid ejection module 20.

FIG. 2 is a plan view of the liquid ejection module 20 as viewed from the recording medium P.
As shown in this figure, the liquid ejection module 20 has a configuration in which a plurality of basic liquid ejection units U are arranged along the X direction.
The liquid discharge unit U further includes a plurality of (for example, six) liquid discharge heads 30 arranged along the X direction. Although the details will be described later, the liquid discharge head 30 is a print head having a plurality of nozzles N arranged in two rows inclined with respect to the Y direction that is the conveyance direction of the print medium P.

FIG. 3 is a diagram for explaining the arrangement of the nozzles N in one liquid discharge head 30. Unlike FIG. 2, the case where the nozzle N is seen through from the opposite side of the recording medium P toward the ink discharge direction is shown. FIG.
As described above, one liquid discharge head 30 has a plurality of inclined nozzles N in two rows. Here, a single nozzle arrangement in the liquid discharge head 30 that does not consider the inclination will be described first.

  As shown in FIG. 3, the nozzle N of the liquid ejection head 30 is divided into nozzle rows Na and Nb. In the nozzle arrays Na and Nb, a plurality of nozzles N are arranged at a pitch P1 along the W1 direction (second direction). The nozzle rows Na and Nb are separated by a pitch P2 in the W2 direction orthogonal to the W1 direction. The nozzles N belonging to the nozzle row Na and the nozzles N belonging to the nozzle row Nb are shifted in the W1 direction by a half of the pitch P1.

In FIG. 3, nozzle numbers for specifying the nozzles N and the like are shown below. In this example, for the nozzle row Na, 1, 2,..., 26, 27 are sequentially assigned as nozzle numbers from the nozzle N located at the negative side end in the W1 direction. For the nozzle row Nb, 28, 29,..., 53, 54 are sequentially assigned as nozzle numbers in order from the nozzle N located at the negative end in the W1 direction.
FIG. 3 also shows the correspondence with the color of the ink ejected from the nozzle N. In this example, nozzles N having nozzle numbers “1” to “12” correspond to magenta (M), nozzles N having nozzle numbers “15” to “26” correspond to yellow (Y), The nozzles N having nozzle numbers “29” to “40” correspond to black (Bk), and the nozzles N having nozzle numbers “43” to “54” correspond to cyan (C).
Of the nozzle row Na, the nozzle (nozzle number “27”) located at the positive side end in the W1 direction, and the nozzle (nozzle number “28”) located at the negative side end in the W1 direction of the nozzle row Nb. Is a dummy nozzle that does not eject ink. In addition, the nozzles N having nozzle numbers “13” and “14” between magenta and yellow, and the nozzles N having nozzle numbers “41” and “42” between black and cyan have a partition wall between colors. It is a blank nozzle to ensure
Here, the number of nozzles of the liquid discharge head 30 is 27 in one row including dummy nozzles and blank nozzles (54 in two rows), but this is a measure for simplifying the explanation. Actually, as will be described later, there are several hundreds in a row. Also, the number of dummy nozzles and blank nozzles may actually be larger.

As shown in FIG. 4, the liquid discharge heads 30 are arranged at an angle θ that is non-orthogonal and non-parallel to the Y direction, which is the conveyance direction of the print medium P. FIG. 4 is a view when seen through from the opposite side of the recording medium P toward the ink ejection direction, unlike FIG.
In the example of FIG. 4, the nozzles N belonging to the nozzle row Na and the nozzles N belonging to the nozzle row Nb have the same position (coordinates) in the X direction.
Specifically, when attention is paid to one liquid ejection head 30, one nozzle N (nozzle number is “1”) located at the negative end in the W1 direction in the nozzle row Na in the liquid ejection head 30 of interest. Nozzle N) and one nozzle N (nozzle N whose nozzle number is “29”) located at the negative end in the W1 direction in the nozzle row Nb is Y in the transport direction of the print medium P The angle θ is set so as to pass an imaginary line a extending in a direction parallel to the direction.

Further, the adjacent liquid discharge heads 30 have the following positional relationship with respect to the liquid discharge head 30 of interest. That is, with respect to the liquid discharge head 30 of interest, the two liquid discharge heads 30 located on the left side in the figure are the nozzle N with the nozzle number “17” and the nozzle N with the nozzle number “45”. The positional relationship passes through the virtual line a.
For this reason, when the print medium P is conveyed in the Y direction, the magenta (M) ink ejected from the nozzle N with the nozzle number “1” and the nozzle number “29” in a certain liquid ejection head 30. In the black (Bk) ink ejected from the nozzle N and the liquid ejecting head 30 located two adjacent to the left of the liquid ejecting head 30, yellow (nozzle ejected from the nozzle N having the nozzle number “17”) The ink of Y) and the cyan (C) ink ejected from the nozzle N with the nozzle number “45” are landed at the same position, whereby it is possible to form color dots. .

  In addition, with respect to the focused liquid ejection head 30, the nozzle N of the liquid ejection head 30 located on the left adjacent to the nozzle N with the nozzle number “9”, the nozzle N with the nozzle number “37”, and the focused liquid ejection The nozzle N with the nozzle number “25” and the nozzle N with the nozzle number “53” of the liquid ejection head 30 that are three adjacent to the left of the head 30 also pass through the virtual line a. It is a positional relationship. For this reason, since the two nozzles N of each color overlap each other in the virtual line a, for example, ink is ejected from only the nozzle N located on the upstream side, and ink ejection is restricted from the nozzle N located on the downstream side. Processing is performed.

  In FIG. 4, only the nozzle numbers passing through the imaginary line a are shown. However, for example, the nozzles N having nozzle numbers “2” and “30” in the focused liquid ejection head, and the focused liquid ejection head 30. The nozzles with nozzle numbers “18” and “46” in the two liquid ejection heads 30 adjacent to the left are the same in the X direction. When viewed along the Y direction, the four color nozzles are It is configured to pass. The other nozzles have the same positional relationship.

FIG. 5 is a cross-sectional view showing the structure of one nozzle N in the liquid discharge head 30, and more specifically, a cross section taken along the line gg in FIG. 3 (a cross section perpendicular to the W1 direction). FIG. 3 is a diagram showing a cross section viewed from the positive side in the W1 direction to the negative side).
As shown in FIG. 5, in the liquid discharge head 30, the pressure chamber substrate 44, the diaphragm 46, the sealing body 52, and the support body 54 are provided on the negative side surface in the Z direction of the flow path substrate 42. And a structure (head chip) in which the nozzle plate 62 and the compliance portion 64 are installed on the positive side surface in the Z direction of the flow path substrate 42. Each element of the liquid discharge head 30 is a substantially flat member that is long in the W1 direction as described above, and is fixed to each other by using, for example, an adhesive. The flow path substrate 42 and the pressure chamber substrate 44 are formed of, for example, a silicon single crystal substrate.

  The nozzle N is formed on the nozzle plate 62. As schematically described in FIG. 3, in the liquid ejection head 30, the structure corresponding to the nozzles N belonging to the nozzle row Na and the structure corresponding to the nozzles N belonging to the nozzle row Nb are only half the pitch P1 in the W1 direction. Although they are shifted in relation to each other, they are formed substantially symmetrically, and therefore, the structure of the liquid discharge head 30 will be described below with a focus on the nozzle row Na.

  The flow path substrate 42 is a flat plate material that forms an ink flow path, and an opening 422, a supply flow path 424, and a communication flow path 426 are formed. The supply flow path 424 and the communication flow path 426 are formed for each nozzle N, and the opening 422 is formed so as to be continuous over a plurality of nozzles N that eject ink of the same color.

A support body 54 is fixed to the surface of the flow path substrate 42 on the negative side in the Z direction. The support 54 is formed with an accommodating portion 542 and an introduction channel 544. The accommodating portion 542 is a concave portion (dent) having an outer shape corresponding to the opening 422 of the flow path substrate 42 in a plan view (that is, viewed from the Z direction), and the introduction flow path 544 is a flow path communicating with the accommodating portion 542. It is.
A space in which the opening 422 of the flow path substrate 42 and the accommodating portion 542 of the support 54 communicate with each other functions as a liquid storage chamber (reservoir) Sr. The liquid storage chamber Sr is formed independently for each color of ink, and stores the ink that has passed through the liquid container 14 (see FIG. 1) and the introduction flow path 544. That is, four liquid storage chambers Sr corresponding to different inks are formed in one liquid discharge head 30.

  The element that constitutes the bottom surface of the liquid storage chamber Sr and suppresses (absorbs) ink pressure fluctuations in the liquid storage chamber Sr and the internal flow path is the compliance section 64. The compliance part 64 includes a flexible member formed in a sheet shape, for example. Specifically, the compliance part 64 flows so that the opening 422 and each supply flow path 424 in the flow path substrate 42 are closed. It is fixed to the surface of the road substrate 42.

A diaphragm 46 is installed on the surface of the pressure chamber substrate 44 opposite to the flow path substrate 42. The vibration plate 46 is a plate-like member that can elastically vibrate, and is configured by stacking an elastic film formed of an elastic material such as silicon oxide and an insulating film formed of an insulating material such as zirconium oxide. Is done. The diaphragm 46 and the flow path substrate 42 are opposed to each other with an interval inside each opening 442 of the pressure chamber substrate 44. A space sandwiched between the flow path substrate 42 and the diaphragm 46 inside each opening 442 functions as a pressure chamber Sc that applies pressure to the ink. Each pressure chamber Sc communicates with the nozzle N via the communication channel 426 of the channel substrate 42.
A piezoelectric element Pzt corresponding to the nozzle N (pressure chamber Sc) is formed for each nozzle N on the surface of the vibration plate 46 opposite to the pressure chamber substrate 44.

  The piezoelectric element Pzt includes a driving electrode 72 formed individually for each piezoelectric element Pzt on the surface of the diaphragm 46, a piezoelectric body 74 formed on the surface of the driving electrode 72, and a surface of the piezoelectric body 74. And a drive electrode 76 formed on the substrate. A region facing the piezoelectric body 74 with the drive electrodes 72 and 76 functions as the piezoelectric element Pzt.

  The piezoelectric body 74 is formed by a process including heat treatment (firing), for example. Specifically, the piezoelectric material applied on the surface of the diaphragm 46 on which the plurality of drive electrodes 72 are formed is fired by heat treatment in a firing furnace and then shaped for each piezoelectric element Pzt (for example, using plasma). The piezoelectric body 74 is formed by milling.

A part of the drive electrode 72 is exposed from the sealing body 52 and the support body 54, and a wiring board (not shown) is connected to the exposed portion to apply the voltage Vout of the drive signal. ing. On the other hand, a common constant voltage (for example, a voltage V _BS described later) is applied to the drive electrode 76 over the plurality of piezoelectric elements Pzt. The drive electrode 76 is electrically connected to a plurality of piezoelectric elements Pzt. Therefore, the drive electrode 76 may be formed separately for each piezoelectric element Pzt and connected to a common wiring, or may be connected to the plurality of piezoelectric elements Pzt. It is good also as a continuous structure.

  In the piezoelectric element Pzt having such a configuration, the center portion of the piezoelectric element Pzt with respect to the periphery in FIG. Bends upward or downward relative to the part. Specifically, the piezoelectric element Pzt is configured to bend upward when the voltage Vout of the drive signal applied via the drive electrode 72 is low, and bend downward when the voltage Vout is high. ing.

Here, if the ink is bent upward, the internal volume of the pressure chamber Sc is expanded, so that the ink is drawn from the liquid storage chamber Sr. On the other hand, if the ink is bent downward, the internal volume of the pressure chamber Sc is reduced. Depending on the degree of reduction, ink droplets are ejected from the nozzle N.
As described above, when an appropriate driving signal is applied to the piezoelectric element Pzt, the ink drawn from the liquid storage chamber Sr is ejected from the nozzle N due to the displacement of the piezoelectric element Pzt.

  As will be described later, the timing at which ink is ejected from a plurality of (in the example of FIG. 3, 48 nozzles excluding dummy nozzles and blank nozzles) N in one liquid ejection head 30 is common. Therefore, in the configuration in which the nozzle array Na (Nb) is inclined at an angle θ with respect to the Y direction that is the transport direction, dots are formed on the print medium P that is transported in the Y direction as follows.

FIG. 6 is a diagram showing dots formed by ink ejected from these nozzles N, for example, focusing on nozzles N having nozzle numbers “1” to “6” in the liquid ejection head 30. .
As shown in this figure, every time the print medium P is conveyed by the pitch Dy in the Y direction, the shots # 1, # 2, # 3, ... Magenta (M) ink is ejected all at the same time. The dot pitch Dx in the X direction of the dots (that is, the direction orthogonal to the transport direction of the print medium P) is:
P1 · sinθ
It is represented by Here, P1 is the arrangement pitch of the nozzles N along the W1 direction as described above.

  For the sake of explanation, FIG. 6 shows an example in which dots are formed by ejecting ink once from the nozzle N when the print medium P is conveyed by the pitch Dy. There is also a configuration in which the ink is ejected from the nozzle N twice or more as will be described later.

  Incidentally, in general, a bitmap image (image data IMG) input from a host computer or the like is defined by an orthogonal arrangement (dot matrix) of pixels. On the other hand, in the present embodiment, an image is formed by simultaneously ejecting ink from nozzles N arranged at an angle θ with respect to the Y direction. Here, when the image data IMG is temporarily stored in the memory (DRAM), as described later, the orthogonal array is converted in advance in accordance with the inclination of the nozzle, and if the DMA transfer is not performed, high-speed printing is performed. Can not be.

  Here, an electrical configuration of the printing apparatus 1 which is a precondition for array conversion and the like will be described.

FIG. 7 is a block diagram illustrating an electrical configuration of the printing apparatus 1.
As shown in this figure, the printing apparatus 1 has a configuration in which a liquid ejection module 20 is connected to a control unit 10.
The liquid discharge module 20 includes a plurality of liquid discharge units U as described above, and the liquid discharge unit U further includes a plurality (six) of liquid discharge heads 30. Here, if the number of liquid ejection units U is, for example, an integer U, the number of liquid ejection heads 30 is 6 · U.
The control unit 10 controls the 6 · U liquid ejection heads 30 independently. Here, for convenience, the control of one liquid ejection head 30 will be described as a representative.

As illustrated in FIG. 7, the control unit 10 includes a control unit 100 and drive circuits 120-a and 120-b.
Among these, the control unit 100 is a kind of microcomputer having a CPU, a RAM, a ROM, and the like, and when image data IMG to be printed is supplied from a host computer or the like, by executing a predetermined program, Various control signals for controlling each unit are output.

Specifically, first, the control unit 100 repeatedly supplies digital data dA to the drive circuit 120a, and similarly supplies digital data dB to the drive circuit 120b. Here, the data dA defines the waveform of the drive signal COM-A supplied to the head unit 3, and the data dB defines the waveform of the drive signal COM-B.
The drive circuit 120a performs analog conversion on the data dA, and then, for example, performs class D amplification, and outputs the amplified signal as the drive signal COM-A. Similarly, the drive circuit 120b performs analog conversion of the data dB, amplifies the class D, and outputs the amplified signal as the drive signal COM-B.
The drive circuits 120a and 120b differ only in the waveform of the input data and the output drive signal, and the circuit configuration is the same.

Secondly, the control unit 110 supplies various signals including print data SI and the like to the liquid ejection head in synchronization with the control with respect to the transport mechanism 12. Various signals supplied to the liquid ejection head unit 3 include print data SI that defines the amount of ink to be ejected from the nozzle N, a clock signal that is used to transfer the print data, a timing signal that defines a printing cycle, and the like. Is included.
In addition, the control unit 100 controls the transport mechanism 12 to control the transport of the print medium P in the Y direction, but the configuration for this is omitted.

In this embodiment, four dots of large dots, medium dots, small dots, and non-recording are expressed by ejecting ink from one nozzle N at most twice in a printing cycle for one dot. In order to express these four gradations, in this embodiment, two types of drive signals COM-A and COM-B are prepared, and the printing cycle is divided into a first half period and a second half period, respectively. The driving signals COM-A and COM-B are selected (or not selected) according to the gradations to be expressed in the first half and the second half of the printing cycle, and supplied to one end of the piezoelectric element Pzt. It has become.
Here, for convenience of description, waveforms of the drive signals COM-A and COM-B will be described.

  As shown in FIG. 7, the drive signal COM-A has a waveform in which the trapezoidal waveform Adp1 arranged in the first half period and the trapezoidal waveform Adp2 arranged in the second half period are continuous in the printing cycle. . The trapezoidal waveforms Adp1 and Adp2 are substantially identical to each other. If each of them is supplied to one end of the piezoelectric element Pzt, a predetermined amount from the nozzle N corresponding to the piezoelectric element Pzt, specifically, This is a waveform for ejecting a certain amount of ink.

  The drive signal COM-B has a waveform in which the trapezoidal waveform Bdp1 arranged in the first half period and the trapezoidal waveform Bdp2 arranged in the second half period are continuous. The trapezoidal waveforms Bdp1 and Bdp2 are different from each other. Of these, the trapezoidal waveform Bdp1 is a waveform for causing the ink in the vicinity of the nozzle N to slightly vibrate to prevent an increase in the viscosity of the ink. For this reason, even if the trapezoidal waveform Bdp1 is supplied to one end of the piezoelectric element Pzt, ink droplets are not ejected from the nozzle N corresponding to the piezoelectric element Pzt. Further, if the trapezoidal waveform Bdp2 is assumed to be supplied to one end of the piezoelectric element Pzt, the trapezoidal waveform Bdp2 is a waveform that causes a smaller amount of ink to be ejected from the nozzle N corresponding to the piezoelectric element Pzt.

Therefore, when a large dot is to be formed, the drive signal COM-A (Adp1, Adp2) is selected at one end of the piezoelectric element Pzt of the nozzle N that forms the large dot over the first half period and the second half period of the printing cycle. Medium amount of ink is ejected in two steps, so that the respective inks land on the medium P, and as a result, the target large dots are formed. become.
When medium dots are to be formed, the drive signal COM-A (Adp1) is selected at one end of the piezoelectric element Pzt of the nozzle N that forms the medium dots during the first half of the printing cycle and is driven during the second half. If the signal COM-B (Bdp2) is selected and supplied, medium and small inks are ejected in two portions, so that the respective inks land on the medium P, and as a result, As a result, medium dots are formed as intended.
On the other hand, when a small dot is to be formed, neither of the drive signals COM-A and COM-B is selected at one end of the piezoelectric element Pzt of the nozzle N that forms the small dot in the first half of the printing cycle. If the drive signal COM-B (Bdp2) is selected and supplied in the second half period, a small amount of ink is ejected only once, so that the target small dots are formed on the medium P.
For non-recording, the drive signal COM-B (Bdp1) is selected at one end of the piezoelectric element Pzt of the corresponding nozzle N in the first half period of the printing cycle, and the drive signal COM--A, If none of COM-B is selected, the ink in the vicinity of the nozzle N only slightly vibrates during the first half period, and the ink is not ejected.

One liquid discharge head 30 is electrically connected to each of the interface (I / F) 205, the selection control unit 210, and each of the piezoelectric elements Pzt, in addition to the plurality of piezoelectric elements Pzt described above. And a plurality of selection units 230 formed. The interface 205 inputs the print data SI and supplies it to the selection control unit 210. The selection control unit 210 is supplied from the control unit 100 as to whether one of the drive signals COM-A and COM-B should be selected for each of the selection units 230 (or both should be unselected). Instructed by various signals, the selection unit 230 selects the drive signals COM-A and COM-B according to the instructions of the selection control unit 210, and applies them to one end of the piezoelectric element Pzt as a drive signal.
In FIG. 7, the voltage of the drive signal selected by the selection unit 230 is denoted as Vout in order to distinguish it from the drive signals COM-A and COM-B.
The other end of each of the piezoelectric elements Pzt, a voltage V _BS is commonly applied.

As described above, the selection unit 230 selects (or does not select) the drive signals COM-A and COM-B in accordance with an instruction from the selection control unit 210, and applies them to one end of the piezoelectric element Pzt. For this reason, each piezoelectric element Pzt is driven according to the dot size defined by the print data SI.
Note that the drive signals COM-A and COM-B shown in FIG. 7 are merely examples. Actually, various waveforms prepared in advance are used in combination according to the conveyance speed and characteristics of the print medium P.
Here, the example in which the piezoelectric element Pzt bends upward as the voltage Vout decreases has been described. However, if the stacking order of the drive electrodes 72 and 76 is reversed, the piezoelectric element Pzt will increase in voltage. Along with this, it will bend upward. As described above, in the configuration in which the piezoelectric element Pzt bends upward as the voltage increases, the drive signals COM-A and COM-B illustrated in the figure have waveforms that are inverted with reference to the voltage Vc.
As described above, one dot is formed on the printing medium P by discharging ink twice (at most) over the printing cycle, but one dot may be formed by discharging ink once.

FIG. 8 is a block diagram illustrating a configuration of the control unit 100. In this figure, the functions from image data IMG to output of print data are shown, and the functions of outputting data dA, dB, clock signals, and other signals are omitted.
The control unit 100 includes a DRAM (Dynamic Random Access Memory) 110, an SRAM (Static Random Access Memory) 112, a first processing unit 131, a second processing unit 132, and a third processing unit 133. Among these, the DRAM 110 is used as a temporary work memory, and is divided into a first area, a second area, and a third area for convenience. Further, the SRAM 112 is used as a buffer, and is faster in storing / reading than the DRAM 110.

  The outline of the control unit 100 will be described. The first area stores image data IMG supplied from the host computer. The basic processing unit 122 performs individual difference correction for each nozzle, error diffusion processing, and the like on the image data IMG stored in the first area. The second area stores image data processed by the basic processing unit 122. The first processing unit 131 performs an array conversion process, which will be described later, on the image data stored in the second area, and stores the image data in the third area (first storage unit). When there is a defective nozzle in the liquid ejection head 30, the first processing unit 131 complements and forms the dots that cannot be formed by the defective nozzle with respect to the image data stored in the second region. Complementary processing may be performed. The second processing unit 132 stores the image data stored in the third area in the SRAM 112 (second storage unit) in a format to be described later. The third processing unit 133 reads data stored in the SRAM 112 by DMA (Direct Memory Access) as will be described later, and supplies it as print data SI to the interface 205 on the liquid ejection head 30 side.

FIG. 9 is a diagram for explaining the outline of the array conversion process executed by the control unit 100.
(A) of this figure is a figure which shows the example of the image data stored in the 2nd area | region, ie, the image data processed by the basic process part 122. FIG. In (a), the state in which the image data is stored in the second area is indicated by horizontal lines L1, L2, L3,. In the figure, the line Li indicates an arbitrary i-th line among the image data stored in the second area. When the image is composed of one line to the last max line, i is a line number for generally describing the line, and is an integer from 1 to max. For each storage area of the DRAM 110 and SRAM 112 described later, the right direction is the column direction, that is, the storage / reading (scanning) direction, and the downward direction is the row direction.

(B) shows an example of image data stored in the third region, that is, image data that has undergone an array conversion process.
In this array conversion process, the image data stored in the second region is rotated by 90 degrees counterclockwise in this example, and each line is further rotated by an amount corresponding to the angle θ for each line. The line direction is shifted. Note that the line direction here is after 90 degrees of rotation, so the storage area of the memory is the vertical direction (row direction) in the figure.

In this example, the lower the line number, the larger the upward shift amount.
Specifically, the total shift amount in the line Li can be expressed by a function m (i) having the line number i as an argument as in the following equation (1).
m (i) = n · (max−i) (1)

Here, n is a shift amount when viewed between adjacent lines, and is expressed as, for example, the following equation (2).
n = (P1 · cos θ) / Dy (2)
In this equation, P1 is the pitch between adjacent nozzles N as described in FIGS. 3 and 6, and Dy is the pitch of the printing medium P conveyed in the printing cycle, that is, Y of the dots to be formed. The pitch of the direction. That is, the shift amount n indicates how many dots formed in the Y direction correspond to the distance of the Y direction component of the pitch P1.
For the sake of explanation, FIG. 6 shows an example in which the shift amount n is “2”, but in actuality it is, for example, about “3” to “6”.

As shown in FIG. 9B, the image data stored in the third area after being subjected to the array conversion is shown in the direction of the arrow in the figure if the nozzles N are in one row and are monochromatic in the liquid ejection head 30. It may be read out along the line and supplied to the liquid discharge head 30. However, in practice, for color printing, it is necessary to prepare four colors of magenta (M), yellow (Y), black (Bk), and cyan (C) as nozzles in the liquid discharge head.
Further, as described above, the nozzle rows Na and Nb are divided into two rows, and the nozzles of the nozzle row Na are arranged in the order of magenta (M), blank, yellow (Y), and dummy. The nozzles are arranged in the order of dummy, black (Bk), blank, and cyan (C).
On the other hand, the blank and dummy nozzles do not eject ink, but have substantially the same structure as the nozzles that eject ink so that they can be used as a straight head described later. For this reason, there are terminals to the piezoelectric elements corresponding to the blank and dummy nozzles, and it is necessary to supply invalid data (data for not discharging ink) as the print data SI.

Therefore, actually, as shown in FIG. 10B, in the third area, in the nozzle row Na, there is a blank between the data corresponding to magenta (M) and yellow (Y). Corresponding invalid data is stored in a state inserted by the first processing unit 131.
In DMA transfer, it is preferable to execute a unit of multiples of a certain amount (block). However, in a configuration in which only magenta (M), blank, and yellow (Y) data is transferred, multiples of blocks are used. However, inefficient transfer may occur. Therefore, a fraction (Allign) that is insufficient for the multiple of the block is added after yellow (Y).
Here, the magenta (M) and yellow (Y) nozzle row Na has been described, but the same applies to the nozzle row Nb. That is, although not particularly illustrated, invalid data corresponding to a blank is inserted between data corresponding to black (Bk) and cyan (C), and the number of multiples of the block is insufficient following cyan (C). A fraction (Allign) is added.

As an example of an actual nozzle, for example, as shown in FIG. 10A, in the nozzle row Na, 241 nozzle numbers from “1” to “241” correspond to magenta (M). 10 nozzle numbers from “242” to “251” are nozzles corresponding to blanks, and 241 nozzle numbers from “252” to “492” are nozzles corresponding to yellow (Y). is there. Next to yellow (Y), that is, at the rear end of the nozzle row Na, 19 dummy nozzles to which nozzle numbers are not assigned continue.
In the nozzle row Nb, 19 dummy nozzles to which no nozzle number is assigned are continuous at the front end. Next to this dummy nozzle, 241 nozzle numbers from “493” to “733” are nozzles corresponding to black (Bk), and 10 nozzle numbers from “734” to “743” are blank. 241 nozzles corresponding to cyan (C) are nozzles corresponding to nozzle numbers “744” to “984”.

Now, as shown in FIG. 10B, the data stored in the third area is read out in the order from the top by the second processing unit 132 along the direction of the arrow in FIG. Stored in Here, the data of one block indicated by the arrow is stored as shown in FIG.
In the figure, for example, a square frame (box) denoted by nozzle 1 (M) indicates that eight shots of data corresponding to magenta (M) with the nozzle number “1” are stored. Here, the period required for discharging one shot corresponds to the printing cycle. As described above, when the four gradations are expressed, the print data is 2 bits, and therefore 16-bit data is stored in the box denoted by nozzle 1 (M). Note that (d) corresponds to a blank. A square frame labeled “Allign” is data corresponding to the fraction when DMA transfer is performed as described above.
The nozzle row Nb is stored as shown in FIG.

Data stored in the SRAM 112 in the order of nozzle numbers is DMA-transferred by the third processing unit 133 to the interface 205 on the liquid ejection head 30 side. During this DMA transfer, in the nozzle row Na, invalid data of dummy nozzles following yellow (Y) is added by offsetting the address, and in the nozzle row Nb, data before black (Bk) is added. Invalid data of the dummy nozzle is added in the same manner.
In the liquid discharge head 30, ink is discharged from the nozzles according to the DMA transferred data. In the liquid discharge head 30 (interface 205), data corresponding to the fraction is ignored.

By the way, when the liquid discharge head 30 is used as a straight head, that is, as shown in FIG. 12A, when the liquid discharge head 30 is arranged in a direction orthogonal to the transport direction, one liquid discharge head 30 is composed of monochromatic ink. Since there is no need to secure a partition between colors, a blank nozzle is not provided. For this reason, as shown in FIG. 12B, it is not necessary to arrange and store invalid data corresponding to the blank nozzle in the SRAM 112.
Note that the straight head does not require an array conversion process in the first place.

Conventionally, when printing data processed for each color is transferred to the liquid ejection head 30 at high speed, an SRAM as a buffer is prepared for each color, and the capacity is secured to cover the number of nozzles (maximum specification). There was a need to do.
In this embodiment, the SRAM 112 is shared by magenta (M) and yellow (Y), and the SRAM 112 is shared by black (Bk) and cyan (C), so that the required capacity can be reduced to half.
Further, since data corresponding to the dummy nozzle is added by manipulating the address at the time of DMA transfer, it is not necessary to increase the capacity of the SRAM accordingly.

  In the embodiment, the print medium P is moved in the Y direction with respect to the liquid discharge head 30 having the plurality of nozzles N. Conversely, the liquid discharge head 30 is moved with respect to the print medium P. It may be a configuration. In short, any configuration is acceptable as long as the print medium P moves relative to the liquid ejection head 30.

DESCRIPTION OF SYMBOLS 1 ... Printing apparatus, 10 ... Control unit, 30 ... Liquid discharge head (printing head), 100 ... Control part, 110 ... DRAM, 112 ... SRAM, 131 ... 1st process part, 131 ... 2nd process part, 133 ... 1st 3 processing units.

Claims (4)

The relative movement direction of the print medium and the print head having a plurality of nozzles and the arrangement direction of the plurality of nozzles intersect at a non-orthogonal and non-parallel angle,
The plurality of nozzles includes a first nozzle group that ejects a first ink, a second nozzle group that ejects a second ink different from the first ink, and the first nozzle group and the second nozzle group. A printing apparatus that is divided into a group of blank nozzles arranged in between,
A first processing unit that stores print data corresponding to the first nozzle group, the blank nozzle group, and the second nozzle group in a first storage unit;
A second processing unit for storing the print data stored in the first storage unit in the second storage unit in an order corresponding to the arrangement of the nozzles;
A third processing unit that ejects ink based on the print data stored in the second storage unit;
A printing apparatus comprising: At the front end or rear end of the nozzle row of the first nozzle group, the blank nozzle group, and the second nozzle group, a dummy nozzle group is provided,
The third processing unit includes:
The printing apparatus according to claim 1, wherein data is added to the dummy nozzle group at a front end or a rear end of the print data stored in the first storage unit. The relative movement direction of the print medium and the print head having a plurality of nozzles and the arrangement direction of the plurality of nozzles intersect at a non-orthogonal and non-parallel angle,
The plurality of nozzles includes a first nozzle group that ejects a first ink, a second nozzle group that ejects a second ink different from the first ink, and the first nozzle group and the second nozzle group. A control device for controlling a printing device divided into a group of blank nozzles disposed between
A first processing unit that stores print data corresponding to the first nozzle group, the blank nozzle group, and the second nozzle group in a first storage unit;
A second processing unit for storing the print data stored in the first storage unit in the second storage unit in an order corresponding to the arrangement of the nozzles;
A third processing unit that ejects ink based on the print data stored in the second storage unit;
A control device comprising: The relative movement direction of the print medium and the print head having a plurality of nozzles and the arrangement direction of the plurality of nozzles intersect at a non-orthogonal and non-parallel angle,
The plurality of nozzles includes a first nozzle group that ejects a first ink, a second nozzle group that ejects a second ink different from the first ink, and the first nozzle group and the second nozzle group. A control method for a printing apparatus divided into a group of blank nozzles arranged in between,
Print data corresponding to the first nozzle group, the blank nozzle group, and the second nozzle group is stored in a first storage unit;
The print data stored in the first storage unit is stored in the second storage unit in the order according to the arrangement of the nozzles,
A control method, wherein ink is ejected based on the print data stored in the second storage unit.

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