JP2008012732A - Printer, printing method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a burden on control for improvement of an image quality in a printer. <P>SOLUTION: The printer has a commanding tone value outputting part and a commanding tone value converting part. The commanding tone value outputting part outputs a commanding tone value according to a quantity of ink delivered, outputting a first commanding tone value of a predetermined bit number for a certain color and outputting a second commanding tone value of a larger bit number than the predetermined bit number for the other color. The commanding tone value converting part converts the second commanding tone value, converting contents of the predetermined bit number in the second commanding tone value to the same contents as those of the first commanding tone value in the case where the quantity of ink delivered for the certain color is delivered by the other color. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing apparatus, a printing method, and a program.

Some printing apparatuses perform printing by forming dots according to gradation. For example, there is an ink jet printer that performs printing using a command gradation value for each dot (see, for example, Patent Document 1). In this printer, a predetermined amount of ink is ejected by controlling the head in accordance with the command gradation value.
JP 2005-305832 A

In this type of printing apparatus, further improvement in image quality has become an essential issue for development. In order to achieve this problem, it is considered to increase the number of gradations for a specific color. In this case, the number of bits of the command gradation value is increased for that color. For example, a 2-bit command gradation value is used for a certain color, while a 3-bit or 4-bit command gradation value is used for another color (specific color).
Here, considering the control on the head side, the content of the command gradation value is preferably the same if the ink discharge amount is the same. This is because the number of judgment objects can be reduced and the control burden is reduced.

  The present invention has been made in view of such circumstances, and an object thereof is to reduce a control burden.

The main invention for achieving the object is as follows:
(A) A command gradation value output unit that outputs a command gradation value corresponding to the amount of ink to be ejected,
A command gradation value output unit that outputs a first command gradation value having a predetermined number of bits for a certain color and outputs a second command gradation value having a number of bits larger than the predetermined number of bits for other colors; ,
(B) a command tone value conversion unit for converting the second command tone value;
When the amount of ink that can be ejected with a certain color is ejected with the other color, the content of the predetermined number of bits in the second command tone value is converted to the same content as the first command tone value A command gradation value conversion unit to perform,
(C).

  Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

That is, (A) a command tone value output unit that outputs a command tone value corresponding to the amount of ink to be ejected, and outputs a first command tone value having a predetermined number of bits for a certain color, A command tone value output unit that outputs a second command tone value having a bit number larger than the predetermined bit number, and (B) a command tone value conversion unit that converts the second command tone value When the amount of ink that can be ejected with a certain color is ejected with the other color, the content of the predetermined number of bits in the second command gradation value is defined as the first command gradation value. A command gradation value conversion unit that converts the same content and a printing apparatus having (C) can be realized.
According to such a printing apparatus, when the amount of ink that can be ejected in a certain color is designated in another color, the content of the predetermined number of bits in the second command tone value is the content of the first command tone value. Will be the same. For this reason, discharge control for a certain color and discharge control for another color can be made common. As a result, the control burden can be reduced.

In this printing apparatus, the command tone value conversion unit converts the content of the predetermined number of bits from the least significant bit in the second command tone value to the same content as the first command tone value. Is preferred.
According to such a printing apparatus, when the amount of ink that can be ejected in a certain color is specified in another color, the content of the predetermined number of bits from the least significant bit in the second command gradation value is the first command level. The content of the key value is the same. For this reason, the control by the second command tone value can be easily made the same as the control by the first command tone value.

In this printing apparatus, it is preferable that the command gradation value conversion unit sets the content of bits other than the predetermined number of bits in the second command gradation value to data [0].
According to such a printing apparatus, when the amount of ink that can be ejected in a certain color is designated in another color, the first command gradation value and the second command gradation value are different although the number of bits is different. And show the same value. For this reason, the control with the second command gradation value can be easily made the same as the control with the first command gradation value.

In this printing apparatus, when the command tone value conversion unit causes the ink other than the amount that can be ejected with a certain color to be ejected with the other color, the second command tone It is preferable that the content of any bit other than the predetermined number of bits in the value is data [1].
According to such a printing apparatus, the fact that the amount of ink ejected in other colors is not included in the amount of ink ejectable in a certain color is identified based on the contents of bits other than the predetermined number of bits. it can.

In such a printing apparatus, the command gradation value conversion unit may cause the amount of ink other than the amount of ink that can be ejected with the certain color to be ejected with the other color than the predetermined number of bits. A configuration in which the content of the one higher-order bit is data [1] is preferable.
According to such a printing apparatus, the number of bits of the second command gradation value can be reduced as much as possible.

In this printing apparatus, the dot of a certain color is formed with a predetermined number of gradations based on the first command gradation value, and the dots of the other colors are formed based on the second command gradation value. A configuration having a head formed with another predetermined number of gradations larger than the predetermined number of gradations is preferable. In addition, the head includes an element that operates to eject the ink, and a head-side controller that performs control to operate the element based on the first command gradation value and the second command gradation value And the structure which has these is preferable.
According to such a printing apparatus, ejection control for a certain color and ejection control for other colors can be made common, and the control burden can be reduced.

Such a printing apparatus is preferably configured to include a cable for electrically connecting the main controller and the head-side controller.
According to such a printing apparatus, since the first command gradation value and the second command gradation value are transmitted to the head-side controller through the cable, the degree of freedom regarding the head arrangement is increased. For example, it can be used by moving the head.

  In this printing apparatus, it is preferable that the command gradation value conversion unit is provided in either the main controller or the head-side controller.

In this printing apparatus, the command gradation value output unit outputs the command gradation value obtained by combining a plurality of bits of data, and the predetermined color is constituted by a predetermined number of sets of data. It is preferable to output the first command gradation value and output the second command gradation value composed of another predetermined number of data for the other colors.
According to such a printing apparatus, processing efficiency can be improved.

In this printing apparatus, the command gradation value output unit outputs the command gradation value in which 2-bit data is set as one set, and the certain color is constituted by a set of data. It is preferable that the 2-bit first command gradation value is output, and the 4-bit second command gradation value composed of two sets of data is output for the other colors.
According to such a printing apparatus, processing efficiency can be improved.

In this printing apparatus, it is preferable that the certain color is black and yellow, and the other color is cyan and magenta.
According to such a printing apparatus, the number of bits of the second command gradation value used for cyan and magenta is larger than the number of bits of the first command gradation value used for black and yellow. Print with fine density. Thereby, color reproducibility can be improved.

It is also clarified that the following printing apparatus can be realized.
That is, (A) a command tone value output unit that outputs a command tone value in which 2-bit data is set as one set in accordance with the amount of ink to be ejected. 2 bits of the first command gradation value are output, and for the other colors, the second command gradation value of 4 bits, which is composed of two sets of data and is larger than the predetermined number of bits, is output. A command tone value output unit; and (B) a command tone value conversion unit for converting the second command tone value, wherein the amount of ink that can be ejected in the certain color is ejected in the other color. The content of the predetermined number of bits from the least significant bit in the second command gradation value is converted to the same content as the first command gradation value, and the predetermined number of bits in the second command gradation value The contents of other bits are set to data [0], and ejection can be performed in the certain color. When the ink amount other than the ink amount is ejected in the other color, the bit other than the predetermined bit number in the second command gradation value, which is one bit higher than the predetermined bit number (C) a dot of a certain color is formed with a predetermined number of gradations based on the first command gradation value, and the second command is converted into data [1]. A head for forming dots of the other color with another predetermined number of gradations greater than the predetermined number of gradations based on a gradation value, the element operating to discharge the ink; A head side controller that performs control for operating the element based on one command gradation value and the second command gradation value; and (D) between the main controller and the head side controller. And an electrically connecting cable ( ) The command gradation value conversion unit is provided in either the main controller or the head-side controller, (F) the certain color is black and yellow, and (G) the other color is It is also clear that printing devices can be realized, cyan and magenta.
According to such a printing apparatus, since almost all the effects described above are exhibited, the object of the present invention can be achieved most effectively.

It is also clarified that the following printing method can be realized.
That is, (A) Amount of ink to be ejected with a first command gradation value having a predetermined number of bits for a certain color and a second command gradation value having a number of bits larger than the predetermined number of bits for another color (B) when the amount of ink that can be ejected in a certain color is ejected in the other color, the content of the predetermined number of bits in the second command gradation value is It is also clarified that a printing method for performing conversion to the same content as the first command gradation value can be realized.

It is also revealed that the following program can be realized.
That is, (A) a program for controlling the printing apparatus, (B) a first command gradation value having a predetermined number of bits for a certain color, and bits larger than the predetermined number of bits for other colors A plurality of second command gradation values are output according to the amount of ink to be ejected, and (C) when the amount of ink that can be ejected in the certain color is ejected in the other color, Converting the content of the predetermined number of bits in the two command gradation values into the same content as the first command gradation value, and (D) forming a dot of the certain color based on the first command gradation value It is also clarified that a program for causing the printing apparatus to form the dots of the other colors based on the second command gradation value can be realized.

=== First Embodiment ===
<About printing devices>
There are many types of printing apparatuses that perform multicolor printing by ejecting inks of a plurality of colors, such as inkjet printers, facsimiles, and plotters. In this specification, a printer / scanner multifunction device 1 (hereinafter also simply referred to as a multifunction device 1), which is a type of printing apparatus, will be described as an example. The multifunction device 1 is a printing apparatus having a printing function for printing an image on a medium and a reading function for reading an image printed on the medium.

<Configuration of MFP 1>
FIG. 1 is a perspective view for explaining the external appearance of the multifunction device 1. FIG. 2 is a block diagram illustrating the configuration of the multifunction machine 1. FIG. 3 is a diagram for explaining the printing mechanism 3. FIG. 4A is a cross-sectional view of the head HD. FIG. 4B is a diagram of the head HD viewed from the nozzle Nz side. FIG. 5A is a block diagram illustrating the configuration of the control unit 56 included in the ASIC 51. FIG. 5B is a block diagram illustrating the configuration of the head control unit 60 included in the control unit 56. FIG. 6 is a diagram for explaining the configuration of one RAM 62 a constituting the first RAM group 62 and the second RAM group 63.

  The multifunction device 1 includes an image reading mechanism 2, a printing mechanism 3, a drive signal generation unit 4, a card slot 5, a sensor group 6, and a main controller 7. In the multi-function device 1, the main controller 7 controls the control target unit, that is, the image reading mechanism 2, the printing mechanism 3, and the drive signal generation unit 4.

  The image reading mechanism 2 corresponds to an image reading unit, and includes a document table 11, a document table cover 12, a reading carriage, and a moving mechanism of the reading carriage, as shown in FIG. The reading carriage and the reading carriage moving mechanism are not shown. In the image reading mechanism 2, the moving mechanism moves the reading carriage when reading an image. The reading carriage outputs an electrical signal corresponding to the image density. Based on this electrical signal, multi-tone image data is acquired. For example, RGB image data expressed in 256 gradations for each RGB color is acquired.

  The printing mechanism 3 is a part that prints an image on a sheet S as a medium, and corresponds to an image printing unit. For example, as shown in FIG. 3, the printing mechanism 3 includes a paper transport mechanism 21, a carriage CR, and a carriage movement mechanism 22. The paper transport mechanism 21 is for transporting the paper S in the transport direction, and includes a platen 23 that supports the paper S from the back side, a transport roller 24 disposed upstream of the platen 23 in the transport direction, and a platen. The sheet discharge roller 25 is disposed on the downstream side of the conveyance direction with respect to the conveyance direction 23, and the conveyance roller 24 and the conveyance motor 26 that is a driving source of the sheet discharge roller 25 are included. The carriage CR is a member to which the ink cartridge IC and the head unit HU are attached. The head unit HU and the main controller 7 are electrically connected via a flexible cable FC. The flexible cable FC electrically connects the main controller 7 and the head-side controller HSC (see FIG. 11). The flexible cable FC increases the degree of freedom regarding the arrangement of the head unit HU (head HD). For example, the movable range of the head unit HU can be expanded. In addition, the flexible cable FC is provided with inter-head signal line groups HSO1 to HSO6 (see FIG. 9). Further, in the state of being attached to the carriage CR, the head HD of the head unit HU has the nozzle Nz formation surface facing the platen 23.

  As shown in FIG. 4A, the head HD includes a case 31, a flow path unit 32, and a piezo element unit 33. The case 31 is a member for housing the piezo element unit 33. The flow path unit 32 is provided with a plurality of series of flow paths corresponding to the nozzles Nz from the common ink chamber 34 to the nozzles Nz through the pressure chambers 35. A part of the pressure chamber 35 is partitioned by the elastic film 36. In addition, on the surface of the elastic film 36 opposite to the pressure chamber 35, island portions 37 are provided corresponding to the pressure chambers 35. The piezo element unit 33 includes a piezo element group 38, an adhesion substrate 39, and an element wiring substrate HFC. The piezo element group 38 has a comb-tooth shape, and each comb-tooth portion corresponds to the piezo element PZT. The piezo element group 38 is fixed to the case 31 via an adhesive substrate 39. The tip surface of each piezo element PZT is bonded to the island portion 37. For this reason, when the piezo element PZT expands and contracts in the longitudinal direction of the element, the island part 37 is pushed toward the pressure chamber 35 or pulled in the opposite direction. Accordingly, a change in pressure occurs in the ink in the pressure chamber 35, and the ink can be ejected from the nozzle Nz. Therefore, the piezo element PZT corresponds to an element that operates to eject ink. The element wiring board HFC is a wiring member for applying a drive signal to each piezo element PZT. A controller unit CU that constitutes a part of the head-side controller HSC is mounted on the element wiring board HFC.

  In addition, the plurality of nozzles Nz provided in the head HD constitute a nozzle row. As shown in FIG. 4B, in the head HD, a plurality of nozzles Nz arranged in the transport direction form a nozzle row. A plurality of nozzle rows are arranged in the carriage movement direction. Specifically, 180 nozzles Nz are arranged in the transport direction at a predetermined interval k · D (k is a coefficient, D is a printing resolution), and a nozzle row is configured by these nozzles Nz. In the present embodiment, the adjacent nozzles Nz are spaced at an interval equivalent to 180 dpi. In this case, the coefficient k is 4 when the print resolution is 720 dpi, and the coefficient k is 8 when the print resolution is 1440 dpi. Four nozzle rows are arranged in the carriage movement direction. One nozzle row corresponds to one piezo element unit 33. In this multifunction device 1, in order from the left end of FIG. 4B, a black ink nozzle row Nk that discharges black ink, a yellow ink nozzle row Ny that discharges yellow ink, a cyan ink nozzle row Nc that discharges cyan ink, and A magenta ink nozzle row Nm for ejecting magenta ink is formed. Therefore, the multi-function device 1 can perform printing in four colors.

  The carriage movement mechanism 22 is for moving the carriage CR in the carriage movement direction. The carriage moving mechanism 22 includes a timing belt 41, a carriage motor 42, and a guide shaft 43. The timing belt 41 is connected to the carriage CR and is spanned between the drive pulley 44 and the idler pulley 45. The carriage motor 42 is a drive source that rotates the drive pulley 44. The guide shaft 43 is a member for guiding the carriage CR in the carriage movement direction. In the carriage moving mechanism 22, the carriage CR can be moved in the carriage movement direction by operating the carriage motor 42. Then, by performing a dot formation operation for intermittently ejecting ink while moving the carriage CR, a row of dots arranged in the carriage movement direction is formed on the paper S. This row of dots is also called a raster line. By alternately repeating the dot forming operation and the transport operation of the paper S, a plurality of raster lines arranged in the transport direction are formed on the paper S, and an image is printed.

  The drive signal generation unit 4 is a part that generates drive signals COM (first drive signal COM_A, second drive signal COM_B, see FIG. 13A) used when ink is ejected from the head HD. The drive signal generator 4 generates drive signals COM having various waveforms based on a control signal (DAC value) from the control unit 56 included in the main controller 7 (ASIC 51). The card slot 5 is a part that is electrically connected to the memory card MC. The memory card MC stores image files to be printed. The sensor group 6 includes a plurality of sensors for detecting the state of each part in the multifunction machine 1. The sensor group 6 includes, for example, a linear encoder 46 for detecting the position of the carriage CR and a rotary encoder (not shown) for detecting the transport amount of the paper S. Then, detection signals from the sensors are output to the main controller 7.

  The main controller 7 is a part that controls the multifunction device 1. As shown in FIG. 2, the main controller 7 includes an ASIC 51 (application specific IC) and a memory 52. The ASIC 51 is an integrated circuit in which a CPU and a control circuit necessary for operating the multifunction device 1 are incorporated. In the memory 52, various programs and data, image files, image data, and the like for controlling the multifunction machine 1 are secured.

<About ASIC51>
The ASIC 51 includes a CPU 53, an external I / F 54, a card I / F 55, and a control unit 56. Each of these units is connected to the internal bus IB of the ASIC 51. The memory 52 and the sensor group 6 are also connected to the internal bus IB. The CPU 53 operates according to a program stored in the memory 52 and controls the operation of the multifunction device 1 in an integrated manner. For example, the CPU 53 controls the image reading mechanism 2 through the control unit 56 to execute the reading process of the image printed on the paper S. Further, the CPU 53 controls the printing mechanism 3 to print an image on the paper S. The external I / F 54 controls communication with the computer CP (host computer) and the external device HW. The card I / F 55 communicates with the memory card MC installed in the card slot 5. For example, an image file is read from the memory card MC. Further, the read image file is stored in the memory 52 through the internal bus IB. The control unit 56 performs various controls based on instructions from the CPU 53. As shown in FIG. 5A, the control unit 56 includes a motor driver 57, an image processing circuit 58, a DAC value output unit 59, and a head control unit 60. The motor driver 57 outputs a motor control signal for controlling the motor. This motor control signal is supplied to the transport motor 26 and the carriage motor 42, for example. The image processing circuit 58 obtains multi-gradation RGB image data from a JPEG format image file, or obtains CMYK dot data for each dot (for each dot printed on the paper S) from the multi-gradation RGB image data. To do. The image processing circuit 58 generates image data suitable for the microweave process from the CMYK dot data. These data will be described later in detail. The DAC value output unit 59 outputs a DAC value as a control signal used in the drive signal generation unit 4. The DAC value determines the voltage value of the drive signal COM that is output from the drive signal generation unit 4. Therefore, the DAC value output unit 59 can generate the drive signal COM having a desired voltage waveform by appropriately changing the output DAC value. The head controller 60 mainly controls the transfer of image data to the head HD. The head controller 60 will be described in detail later.

<About image data>
Here, various data generated by the image processing circuit 58 will be described. The multi-gradation RGB image data is, for example, image data expressed in 256 gradations for each of R, G, and B pixels. In obtaining image data from the multi-tone RGB image data, the image processing circuit 58 first performs color system conversion on the multi-tone RGB image data to obtain multi-tone CMYK image data. For example, 256 gradation CMYK image data is obtained from 256 gradation RGB image data. Then, the image processing circuit 58 converts this multi-tone CMYK image data into CMYK dot data. If the CMYK dot data is obtained, the image processing circuit 58 rearranges the CMYK dot data in the order of formation by the nozzles Nz to obtain image data.

  Here, the CMYK dot data will be described. This CMYK dot data is composed of a group of data indicating the size of dots (dot gradation) for each region where dots can be formed. This area is also called a unit area, and is virtually defined on the paper S as a rectangular area having a size corresponding to the print resolution. Therefore, it can be said that the CMYK dot data is data indicating the dot gradation for each unit region. In this embodiment, for black ink and yellow ink, dot formation can be controlled with four gradations for one unit region. That is, printing can be performed with four gradations of no dot, small dot, small dot, middle dot, and large dot. Therefore, the CMYK dot data used for these inks is 2-bit data for one unit area. The content is data [00] without dots, data [01] with small dots, data [10] with medium dots, and data [11] with large dots. For cyan ink and magenta ink, dot formation can be controlled with six gradations for one unit area. That is, printing can be performed in six gradations: no dots, small dots, middle dots, large dots, huge dots, and extra large dots. Since the 2-bit data is handled as one set in the image processing circuit 58, the CMYK dot data for these inks is 4-bit data for one unit area. For example, the content is data [0000] for no dots, data [0100] for small dots, data [1000] for medium dots, data [1100] for large dots, data [1101] for extra large dots, and data for maximum dots. [1110]. The reason why the 2-bit data is used as a set in this way is to improve processing efficiency. For example, reading and writing of image data to each of the first RAMs 62a to 62f constituting the first RAM group 62 and each of the second RAMs 63a to 63f (described later) constituting the second RAM group 63 are performed using black and yellow inks, A common process can be performed for each ink of cyan and magenta. In this embodiment, 2-bit data composed of a set of data is used for each of black and yellow inks, and 4-bit data composed of two sets of data is used for each ink of cyan and magenta.

  Next, image data will be described. As described above, the image data is generated by rearranging the CMYK dot data. This rearrangement is performed to adapt to the microweave process. Here, the micro-weave process will be briefly described. As described above, the nozzle pitch of each nozzle Nz belonging to the same nozzle row is wider than the interval corresponding to the printing resolution. For this reason, it is not possible to form a raster line adjacent in the transport direction only by moving the carriage CR once. Therefore, in each dot forming operation, a plurality of raster lines are formed at intervals of the nozzle pitch, and by adjusting the transport amount of the paper S in the transport operation, another raster line is formed between the already formed raster lines. Filled by. Such a printing process is called a microweave process. When performing this microweave process, it is necessary to change the dot formation order to an order suitable for the microweave. For this reason, the image processing circuit 58 generates image data by rearranging the CMYK dot data so as to be adapted to the microweave process. Therefore, although the CMYK dot data and the image data are different in dot arrangement order, the contents of each dot (the contents of 2-bit data and 4-bit data) are the same.

  In the following description, the data for each dot (for each unit area) in the image data and the data for each dot in the dot formation data (described later) are also referred to as command gradation values. That is, the data for each dot in the image data and the data for each dot in the dot formation data have a common point in that they represent dot gradation. Therefore, the command gradation value can be expressed as data representing the dot gradation for each unit area. The image data can be said to be composed of a plurality of command gradation values. In the multi function device 1, black and yellow (corresponding to a certain color) ink is controlled using a 2-bit command gradation value (corresponding to a first command gradation value). Yes. Further, each ink of cyan and magenta (corresponding to other colors) is controlled using a 4-bit command gradation value (corresponding to a second command gradation value). The image processing circuit 58 that outputs such a command tone value corresponds to a command tone value output unit, outputs a first command tone value having a predetermined number of bits for a certain color, and other colors. Is output with a second command gradation value having a number of bits larger than the predetermined number of bits.

<About the head control unit 60>
As illustrated in FIG. 5B, the head control unit 60 includes a write / transmission control unit 61, a first RAM group 62 and a second RAM group 63, a six gradation conversion unit 64, and a data selection unit 65. The write transmission control unit 61 reads image data from the memory 52 and writes the read image data to the first RAM group 62 and the second RAM group 63. The write transmission control unit 61 also performs control to read out the image data written in the first RAM group 62 and the second RAM group 63 and transmit the image data to the data selection unit 65 and the six gradation conversion unit 64. The first RAM group 62 and the second RAM group 63 temporarily store image data transferred to the head HD. In addition, SP command data is stored in an empty area that is not used for storing image data. The SP command data is data serving as a basis for switch operation information that determines the operation of the first switch 79 and the second switch 80 (see FIG. 12) of the head-side controller HSC. In other words, it is data for selectively applying the drive signal COM for the head HD to the piezo element PZT.

  The first RAM group 62 is composed of a plurality of first RAMs, and the second RAM group 63 is composed of a plurality of second RAMs. For example, as shown in FIG. 7A, the first RAM group 62 is composed of the first first RAM 62a to the sixth first RAM 62f, and the second RAM group 63 is composed of the first second RAM 63a to the sixth second RAM 63f. ing. In the multi-function device 1, image data is written and read alternately with respect to the first RAM and the second RAM. For example, when image data is read from the first first RAM 62a, the image data is written to the first second RAM 63a. On the other hand, when image data is read from the first first RAM 62a, the image data is written to the first second RAM 63a. For convenience, the first RAM and the second RAM that form a pair are also referred to as a unit. The first unit means a set of the first first RAM 62a and the first second RAM 63a, and the second unit means a set of the second first RAM 62b and the second second RAM 63b. The same applies to other units.

  The first RAMs 62a to 62f and the second RAMs 63a to 63f all have the same configuration. For convenience, the configuration of the first first RAM 62a will be described, and the description of the other components will be omitted. For example, as shown in FIG. 6, the first first RAM 62a has a storage capacity of 192 words × 16 bits. Each word corresponds to one nozzle Nz, and 2-bit data is assigned to each dot. Accordingly, a set of first RAM and second RAM (one unit) is used for black ink and yellow ink using a command gradation value of 2 bits per dot, respectively. For cyan ink and magenta ink using a 4-bit command gradation value per dot, two sets of first RAM and second RAM (two units) are used, respectively.

  The 2-bit data indicated by the symbol X1 (the most significant bit and the second most significant bit in the first word) is a dot formed by the first nozzle Nz (first nozzle) and is n in the carriage movement direction. This is data of the second dot formed. The 2-bit data indicated by symbol X2 (the least significant bit and the second least significant bit in the first word) is a dot formed by the first nozzle Nz, and is (n + 8) in the carriage movement direction. This is data of the second dot formed. Similarly, the 2-bit data (the most significant bit and the second bit in the 180th word) indicated by symbol X3 is a dot formed by the 180th nozzle Nz (final nozzle), and is in the carriage movement direction. This is data of the nth dot formed. SP command data is stored in the area after 181 words.

  The black command tone value (2-bit data) read from one set of the first RAM and the second RAM, and the yellow command tone value read from another set of the first RAM and the second RAM ( 2-bit data) is transmitted to the data selection unit 65 through the write transmission control unit 61. Also, the cyan command gradation value (4-bit data) read from the two sets of the first RAM and the second RAM, and the magenta command gradation read from the other two sets of the first RAM and the second RAM. The value (4-bit data) is transmitted from the write transmission control unit 61 to the 6 gradation conversion unit 64. Then, after predetermined conversion is performed by the six gradation conversion unit 64, the data is transmitted to the data selection unit 65.

<About the 6 gradation conversion unit 64>
Next, the six gradation conversion unit 64 will be described. Here, FIG. 7A is a conceptual diagram for explaining the relationship between the first RAM group 62 and the second RAM group 63 and the six gradation conversion unit 64. FIG. 7B is a conceptual diagram illustrating the functions of the first six gradation conversion unit 64a and the second six gradation conversion unit 64b.

  The six gradation conversion unit 64 corresponds to a gradation value conversion unit or a gradation value conversion circuit, and converts the image data (command gradation value for each dot) generated by the control unit 56 so as to be adapted to the head HD. And output. In this multi-function device 1, the formation of dots is controlled with four gradations for black ink and yellow ink. In the case of cyan ink and magenta ink, dot formation is controlled with six gradations. Here, the ink discharge amount at the large dot of 4 gradations and the ink discharge amount at the maximum dot of 6 gradations are determined by the printing resolution. When the print resolution is the same, these ink ejection amounts are the same. This is because the ink discharge amount necessary for filling the solid is determined by the printing resolution. For example, when the print resolution is 720 dpi, the ink discharge amount at a large dot of 4 gradations and the ink discharge amount at the maximum dot of 6 gradations are both 21 pL. The ink discharge amounts of small dots and medium dots in 4 gradations and the ink discharge amounts of small dots, medium dots, large dots, and extra large dots in 6 gradations are appropriately determined as amounts smaller than 21 pL. It is done. In the present embodiment, as shown in FIG. 8B, the ink discharge amount for small dots of four gradations is 3 pL, and the ink discharge amount for medium dots is 7 pL. On the other hand, as shown in FIG. 8A, the ink discharge amount for small dots of 6 gradations is 1.5 pL, the ink discharge amount for medium dots is 3 pL, the ink discharge amount for large dots is 7 pL, and the ink discharge amount for extra large dots is 14 pL. It is.

  Here, considering the control on the head HD side, the content of the command gradation value is preferably the same if the ink discharge amount is the same. This is because the number of judgment objects can be reduced and the control burden is reduced. If command gradation values having different contents (gradation values) are used for the same ink discharge amount between 4 gradations and 6 gradations, whether the given instruction gradation value is for 4 gradations or 6th floor It is necessary to perform control after judging whether it is a key. On the other hand, when the command gradation value having the same contents in the lower 2 bits in the 4th gradation and the 6th gradation is used for the same ink discharge amount, the control is performed without judging the 4th gradation and the 6th gradation. be able to. In the case of 6 gradations, it is sufficient that the command gradation value is 3 bits. However, in the image processing unit described above, since 2-bit data is handled as one set, 4-bit data is used to express 6 gradations. Here, a 4-bit memory (for example, a shift register) may be mounted on the head HD side, but a wasteful capacity for 1 bit is secured, which is not efficient.

  The six gradation conversion unit 64 (command gradation value conversion unit) is provided to solve such a problem. The first function of the 6 gradation conversion unit 64 is that the content of the instruction gradation value on the side with the larger number of bits is changed to the instruction gradation on the side with the smaller number of bits with respect to the instruction gradation value of a certain ink discharge amount. It is to align with the content of the value. That is, the six gradation conversion unit 64 converts the content of the predetermined number of bits in the second command gradation value into the first command gradation value when the amount of ink that can be ejected in a certain color is ejected in another color. To the same content as The second function of the 6 gradation converter 64 is to convert 6 gradation instruction gradation values given by 4 bits so that they can be handled as 3 bit data. As shown in FIGS. 7A and 7B, the 6-gradation conversion unit 64 (command gradation value conversion unit) converts the magenta image data and the first 6-gradation conversion unit 64a that converts cyan image data. The second six gradation conversion unit 64b is provided.

  The first six gradation conversion unit 64a includes the lower 2 bits of the cyan command gradation value stored in the first units 62a and 63a, and the cyan color stored in the second units 62b and 63b. The upper 2 bits in the command tone value are acquired as the input command tone value. Then, as shown in FIG. 7B, the lower two bits of the converted command gradation value are transmitted to the head HD side through the first inter-head signal line HSO1 as cyan first dot formation data. Further, the upper 2 bits of the converted command gradation value are transmitted as cyan second dot formation data to the head HD side through the second inter-head signal line HSO2. Similarly, the second 6 gradation conversion unit 64b includes the lower 2 bits of the magenta instruction gradation value stored in the third unit and the magenta instruction gradation stored in the fourth unit. The upper 2 bits in the value are acquired as the input command gradation value. Then, the lower 2 bits of the converted command gradation value are transmitted to the head HD side through the third inter-head signal line HSO3 as the first dot formation data of magenta, and the upper 2 bits of the converted command gradation value are converted to magenta. The second dot formation data is transmitted to the head HD side through the fourth inter-head signal line HSO4. The yellow image data (command gradation value group) stored in the fifth unit is transmitted to the head HD side through the fifth inter-head signal line HSO5 as yellow dot formation data, and is transmitted to the sixth unit. The stored black image data is transmitted to the head HD side through the sixth inter-head signal line HSO6 as black dot formation data.

<Conversion of command gradation value>
Next, the conversion of the command gradation value by the 6 gradation conversion unit 64 will be described. Here, FIG. 8A is a diagram illustrating the relationship between the pre-conversion command tone value and the post-conversion command tone value. FIG. 8B is a diagram for explaining command gradation values of four gradations. The first six gradation conversion unit 64a and the second six gradation conversion unit 64b have different instruction gradation values to be converted between cyan and magenta, but the configuration and operation are the same. For this reason, the conversion by the first six gradation conversion unit 64a will be described, and the description of the conversion by the second six gradation conversion unit 64b will be omitted.

  The first 6-gradation converting unit 64a converts the contents of the lower 2 bits in the 6-gradation command gradation value into the 4-gradation command level when the ink amount that can be ejected in black or yellow is ejected in cyan. Same as the contents of key value. In addition, data [0] is set for bits higher than the lower 2 bits. Further, the first six gradation conversion unit 64a causes the amount of ink that is not ejected in black or yellow (corresponding to the amount of ink other than the amount of ink that can be ejected in a certain color) to be ejected in cyan. In this case, the content of the third bit from the lower order in the command gradation value of 6 gradations is set to data [1]. In addition, the first six gradation conversion unit 64a sets the content of the most significant bit to data [0]. This makes it possible to identify that the amount of ink ejected in cyan is an amount that is not ejected in black or yellow based on the contents of the third bit from the bottom. Further, by setting the most significant bit to data [0], the most significant bit is used as a dummy bit. That is, the bits are not used for control. In this way, the post-conversion command gradation value can be handled with substantially 3 bits.

  The post-conversion command tone value is specifically determined as follows. The post-conversion command gradation value indicating the formation of small dots is for ejecting 1.5 pL of ink from the nozzle Nz (head HD). Here, the discharge amount of 1.5 pL is an amount that is not included in the discharge amount of ink in four gradations. For this reason, the content of the post-conversion command tone value is determined by the data [0100] without being limited by the command tone value of 4 tones (2 bits). In this embodiment, the content of the pre-conversion command gradation value corresponding to the ink discharge amount is also data [0100]. Therefore, when the first six gradation conversion unit 64a receives the data [0100] as the pre-conversion command gradation value, it outputs the data [0100] having the same contents as the post-conversion command gradation value.

  The post-conversion command tone value indicating the formation of a medium dot is for ejecting 3 pL of ink from the nozzle Nz. Here, the ink discharge amount of 3 pL is included in the ink discharge amount in four gradations. That is, as shown in FIG. 8B, it is equal to the amount of ink ejected when forming small dots. For this reason, the content of the lower 2 bits in the converted command gradation value is the same as the content of the small dots in the 4 gradations. Specifically, the data is [01]. Data [0] is set for the third bit from the lower order. In addition, data [0] is set to the most significant bit so that the converted command gradation value can be handled as 3-bit data. Therefore, the post-conversion command tone value corresponding to the input command tone value [1000] is data [0001].

  The post-conversion command gradation value indicating the formation of large dots is for ejecting 7 pL of ink from the nozzle Nz. The discharge amount of 7 pL is equal to the discharge amount at the time of forming medium dots in 4 gradations. Therefore, regarding the content of the converted command gradation value, the content of the lower 2 bits is the same as the content (data [10]) at the time of forming the medium dot in 4 gradations, and the upper 2 bits are the data [00 ] To be determined. That is, it is defined as data [0010]. The post-conversion command tone value indicating the formation of an extra large dot is for ejecting 14 pL of ink from the nozzle Nz. This 14 pL discharge amount is not included in the ink discharge amount in the four gradations. For this reason, the content of the post-conversion command tone value is determined by the data [0101] without being limited by the command tone value of 4 tones (2 bits). The post-conversion command gradation value indicating the formation of the maximum dot is for ejecting 21 pL of ink from the nozzle Nz. The discharge amount of 21 pL is equal to the discharge amount at the time of forming a large dot in 4 gradations. For this reason, regarding the contents of the converted command gradation value, the contents of the lower 2 bits are the same as the contents (data [11]) when the large dot is formed in 4 gradations, and the upper 2 bits are the data [00]. ] To be determined. That is, it is defined as data [0011].

  By providing such a 6-gradation conversion unit 64, in this multifunction device 1, the control burden on the head HD side (head-side controller HSC) is reduced, and the processing efficiency can be improved. Further, the 4-bit command gradation value generated by the image processing circuit 58 can be handled as 3-bit data on the head HD side. That is, the command gradation value can be constituted by the lower 3 bits without using the most significant bit. Specifically, the non-formation of dots can be handled as the command tone value [000], and the formation of small dots (ink amount 1.5 pL) can be handled as the command tone value [100]. Similarly, the command gradation value [001] is set for medium dot formation (ink amount 3 pL), the command tone value [010] is set for large dot formation (ink amount 7 pL), and the formation of extra large dots (ink amount 14 pL) is commanded. The gradation value [101] and the maximum dot formation (ink amount 21 pL) can be handled as the command gradation value [011]. Thus, the configuration can be simplified, for example, the memory provided in the head-side controller HSC (each controller unit CU) can be reduced. In the description of the 3-bit command gradation value, the uppermost bit is also referred to as “upper bit” for convenience. The intermediate bits are also referred to as “middle bits”, and the lowest bits are also referred to as “lower bits”.

<About transmission of command gradation value>
Next, transmission of command gradation values (6-gradation post-conversion command gradation values and 4-gradation command gradation values) to the head-side controller HSC will be described. Here, FIG. 9 is a diagram for explaining the inter-head signal line group and the content of the transmitted signal. FIG. 10A is a diagram for explaining the contents of transmission data. FIG. 10B is a diagram illustrating cyan transmission data for the nth dot.

  As illustrated in FIG. 10A, a plurality of types of dot formation data SI and SP command data are transmitted from the data selection unit 65 included in the head control unit 60. The cyan first dot formation data SI_C1 ′ (the lower two bits of the converted command gradation value) is transmitted to the head-side controller HSC through the first inter-head signal line HSO1, and the cyan second dot formation data SI_C2 ′ (conversion) The upper 2 bits of the post-instruction gradation value) are transmitted to the head-side controller HSC through the second inter-head signal line HSO2. Similarly, the first magenta dot formation data SI_M1 ′ (the lower two bits of the converted command gradation value) is transmitted to the head-side controller HSC through the third inter-head signal line HSO3, and the second magenta dot formation data SI_M2 '(The upper two bits of the converted command gradation value) is transmitted to the head-side controller HSC through the fourth inter-head signal line HSO4. Further, yellow dot formation data SI_Y (2-bit data group) is transmitted to the head-side controller HSC through the fifth inter-head signal line HSO5, and black dot formation data SI_K (2-bit data group) is transmitted between the sixth head. The signal is transmitted to the head-side controller HSC through the signal line HSO6.

  Here, the dot formation data SI will be described. The dot formation data SI is obtained by rearranging image data so as to conform to the specifications of the head HD. That is, the higher-order bits in the 2-bit data to be paired are arranged in the order of the nozzles Nz, and the lower-order bits are arranged in the order of the nozzles Nz. The SP command data is transmitted after the lower bit group. For example, the first dot formation data SI_C1 ′ for cyan is composed of lower two bits data of the converted command gradation value. The lower 2 bits of the post-conversion command gradation value correspond to the lower 2 bits of the 3-bit command gradation value used on the head side. That is, among the 2-bit data output from the 6-gradation conversion unit 64, the upper bit is the middle-bit data in the 3-bit data. Further, the lower bit of the 2-bit data becomes the lower bit data in the 3-bit data. Therefore, the first dot formation data SI_C1 ′ includes the middle bit group including the data of the 180th nozzle Nz from the first nozzle Nz and the lower bit including the data of the 180th nozzle Nz from the first nozzle Nz. It consists of a group. The cyan second dot formation data SI_C2 ′ is composed of 180 dummy data groups and an upper bit group including data of the first nozzle Nz to the 180th nozzle Nz. The magenta dot formation data SI_M1 ′ and SI_M2 ′ are also configured in the same manner as the cyan dot formation data SI_C1 ′ and SI_C2 ′. Further, the yellow dot formation data SI_Y and the black dot formation data SI_K are composed of an upper bit group and a lower bit group rearranged in the order of the nozzles Nz as shown in FIG. 10A.

<About the head controller HSC>
The command gradation value transmitted from the main controller 7 (head controller 60) is used by the head controller HSC included in the head HD. Hereinafter, the head-side controller HSC will be described. Here, FIG. 11 is a diagram illustrating a plurality of controller units CU included in the head HD. FIG. 12A is a block diagram illustrating the configuration of a controller unit CU (C) for cyan. FIG. 12B is a diagram for explaining the contents of data input to the upper input terminal SI_U and the lower input terminal SI_D of each controller unit CU.

  The head-side controller HSC has a plurality of controller units CU corresponding to the type of ink to be ejected. As shown in FIG. 11, the head-side controller HSC includes a cyan controller unit CU (C), a magenta controller unit CU (M), a yellow controller unit CU (Y), and a black controller. Unit CU (K). Then, as shown in FIG. 12B, cyan first dot formation data SI_C1 ′, cyan second dot formation data SI_C2 ′, and SP command data are input to the cyan controller unit CU (C). Similarly, the magenta first dot formation data SI_M1 ′, the magenta second dot formation data SI_M2 ′, and the SP command data are input to the magenta controller unit CU (M). Further, yellow dot formation data SI_Y and SP command data are input to the yellow controller unit CU (Y), and black dot formation data SI_K and SP command data are input to the black controller unit CU (K). Entered. Each controller unit CU (C) to CU (K) includes clock CLK, latch signal LAT, change signal (first change signal CH_A, second change signal CH_B), drive signal COM (first drive signal COM_A, The second drive signal COM_B) is also input.

  These controller units CU have the same configuration. Therefore, the configuration of the cyan controller unit CU (C) will be described, and the description of the other controller units CU (M) to CU (K) will be omitted. As shown in FIG. 12A, the cyan controller unit CU (C) includes a first shift register 71, a second shift register 72, a third shift register 73, a first latch circuit 74, and a second latch circuit. 75, a third latch circuit 76, a control logic 77, a decoder 78, a first switch 79, and a second switch 80. Each part excluding the control logic 77, that is, the shift registers 71 to 73, the latch circuits 74 to 76, the decoder 78, the first switch 79, and the second switch 80 are provided for each piezo element PZT. .

  In the first shift register 71, the second shift register 72, and the third shift register 73, the dot formation data SI from the main controller 7 is set. The middle bit of cyan dot formation data SI_C 1 ′ is set in the first shift register 71, and the lower bit is set in the second shift register 72. That is, the middle bit is input from the lower input terminal SI_D, and is set in the first shift register 71 through the control logic 77 and the second shift register 72. Similarly, the lower bits are input from the lower input terminal SI_D, set in the second shift register 72 through the control logic 77. The SP command data transmitted following the lower bit is input from the lower input terminal SI_D and set in the SP shift register 77 a in the control logic 77. In the third shift register 73, the upper bits in the cyan dot formation data SI_C2 ′ are set. That is, this upper bit is input from the upper input terminal SI_U following the dummy data, and is set in the third shift register 73 after passing through the control logic 77.

  The first latch circuit 74, the second latch circuit 75, and the third latch circuit 76 latch the dot formation data SI set in the first shift register 71, the second shift register 72, and the third shift register 73. To do. That is, the first latch circuit 74 latches the middle bit of the dot formation data SI set in the first shift register 71. The second latch circuit 75 latches the lower bits of the dot formation data SI set in the second shift register 72. The third latch circuit 76 latches the upper bits of the dot formation data SI set in the third shift register 73. By being latched by the first latch circuit 74 to the third latch circuit 76, the cyan dot formation data SI is made into a set for each nozzle Nz (that is, a 3-bit command gradation value). Entered.

  The control logic 77 stores switch operation information for determining the operation of the first switch 79 and other switch operation information for determining the operation of the second switch 80. The switch operation information is generated based on the SP command data set in the SP shift register 77a. For example, the pattern register 77b is generated by latching SP command data set in the SP shift register 77a. The switch logic information is output from the control logic 77 to each decoder 78. The contents of the switch operation information are updated at a timing specified by the latch signal LAT, a timing specified by the first change signal CH_A, and a timing specified by the second change signal CH_B.

  The decoder 78 selects the switch operation information and other switch operation information output from the control logic 77 according to the dot formation data SI (3-bit command gradation value) latched by the latch circuits 74 to 76. The selected switch operation information and other switch operation information are output to the first switch 79 and the second switch 80, respectively. The first switch 79 is a switch that operates according to the switch operation information, and controls application of the first drive signal COM_A to the piezo element PZT. The second switch 80 is a switch that operates according to other switch operation information, and controls application of the second drive signal COM_B to the piezo element PZT. Details of the control will be described later.

  Here, the controller unit CU (Y) for yellow and the controller unit CU (K) for black will be supplemented. As shown in FIG. 12B, the upper side input terminals SI_U of these controller units CU are connected to the ground. Therefore, data [0] is set in the corresponding portions of the SP shift register 77a and the third shift register 73. As a result, the dot formation data SI input to the decoder 78 is formally 3-bit data. For example, the large dot data becomes 3-bit data [011] in which data [0] is added to the upper side of the 2-bit data [11] sent from the main controller 7. Similarly, medium dot data becomes 3-bit data [010] in which data [0] is added to the upper side of 2-bit data [10] sent from the main controller 7. As described above, in the 3-bit dot formation data SI (command gradation value) used for cyan and magenta, when the same amount of ink is ejected as black and yellow, the content of the lower 2 bits Are aligned with 2-bit dot formation data SI used in black and yellow. Furthermore, the most significant bit is data [0]. In short, when viewed as 3-bit data, yellow and black dot formation data SI_Y, SI_K and cyan and magenta dot formation data SI_C1, C2, SI_M1, and M2 have the same contents when ejecting the same amount of ink. As a result, each of the controller units CU (C) to CU (K) can handle these data without distinction, and simplifies the control.

<Ink ejection control>
Next, ink ejection control will be described. Here, FIG. 13A is a diagram for explaining the drive signals COM (first drive signal COM_A, second drive signal COM_B) generated by the drive signal generation unit 4. FIG. 13B is a diagram for explaining the drive pulse applied to the piezo element PZT and the amount of ejected ink for each ink type and for each dot formation data SI (for each dot gradation).

  When performing ink ejection control, the main controller 7 generates image data and transmits dot formation data SI to the head-side controller HSC. The main controller 7 (DAC value output unit 59) outputs a DAC value to the drive signal generation unit 4, and the drive signal generation unit 4 outputs a voltage signal corresponding to the DAC value. That is, the drive signal generation unit 4 generates a drive signal COM having a voltage defined by the DAC value. The generation of the drive signal COM is repeated every time the latch signal LAT becomes H level. As a result, the drive signal COM shown in FIG. 13A, that is, the first drive signal COM_A and the second drive signal COM_B are repeatedly generated every repetition period T. The first drive signal COM_A includes a first waveform section SS11 generated in the first period T1, a second waveform section SS12 generated in the second period T2, and a third waveform generated in the third period T3. Part SS13. The second drive signal COM_B is generated in the first waveform section SS21 generated in the first period T1, the second waveform section SS22 generated in the second period T2, and the first waveform section SS22 generated in the third period T3. 3 waveform sections SS23. The first waveform section SS11 included in the first drive signal COM_A includes a first drive pulse PS1. The second waveform section SS12 has a second drive pulse PS2, and the third waveform section SS13 has a third drive pulse PS3. Similarly, the first waveform section 21 included in the second drive signal COM_B has the fourth drive pulse PS4, the second waveform section SS22 has the fifth drive pulse PS5, and the third waveform section SS23 has the sixth drive pulse PS6. .

  These drive pulses PS1 to PS6 are for driving the piezo element PZT to perform a desired operation. In the present embodiment, by applying these drive pulses PS1 to PS6, the piezo element PZT expands and contracts, and the island portion 37 is displaced. Among these drive pulses PS1 to PS6, the first drive pulse PS1 to the third drive pulse PS3 all have the same waveform, and when one drive pulse is applied to the piezo element PZT, it is about 7 pL. Ink is ejected. When the second drive pulse PS2 is applied to the piezo element PZT, about 3 pL of ink is ejected, and when the sixth drive pulse PS6 is applied to the piezo element PZT, about 1.5 pL of ink is ejected. When the fourth drive pulse PS4 is applied to the piezo element PZT, a weak pressure fluctuation that does not eject ink occurs in the ink in the pressure chamber 35, and the meniscus (the free surface of the ink exposed from the nozzle Nz). Is vibrated slightly.

  Next, an operation of applying a necessary portion of the drive signal COM to the piezo element PZT based on the switch operation information will be described. As described above, dot formation data SI (3-bit command gradation value) for cyan and magenta dots has no dot (fine vibration), small dot formation, medium dot formation, large dot formation, and extra large. There are six types corresponding to each of dot formation and maximum dot formation. In this case, the switch operation information is determined as follows. That is, the switch operation information for the first switch 79 corresponding to no dot (command gradation value [000]) is data [000], and the switch operation information for the second switch 80 is data [100]. . The switch operation information for the first switch 79 corresponding to the formation of small dots (command gradation value [100]) is data [000], and the switch operation information for the second switch 80 is data [001]. . The switch operation information for the first switch 79 corresponding to the formation of medium dots (command gradation value [001]) is data [010], and the switch operation information for the second switch 80 is data [000]. . The switch operation information for the first switch 79 corresponding to the formation of large dots (command gradation value [010]) is data [000], and the switch operation information for the second switch 80 is data [010]. . The switch operation information for the first switch 79 corresponding to the formation of extra large dots (command gradation value [101]) is data [100], and the switch operation information for the second switch 80 is data [010]. . The switch operation information for the first switch 79 corresponding to the maximum dot formation (command gradation value [011]) is data [101], and the switch operation information for the second switch 80 is data [010]. .

  The upper bits of each switch operation information define application / non-application of each drive signal COM_A, COM_B in the period T1. That is, when this bit is data [1], the portion of the period T1 in the corresponding drive signal COM_A / COM_B is applied to the piezo element PZT. Similarly, the middle bit of each switch operation information defines application / non-application of each drive signal COM_A, COM_B in the period T2, and the lower bit defines application / non-application of each drive signal COM_A, COM_B in the period T3. .

  Accordingly, in each of cyan and magenta inks, each drive pulse is applied to the piezo element PZT in the pattern shown in FIG. 13B. That is, when there is no dot, the second drive signal COM_B is applied to the piezo element PZT in the period T1. Accordingly, the fourth drive pulse PS4 is applied to the piezo element PZT, and the meniscus is vibrated slightly. In the formation of small dots, the second drive signal COM_B is applied to the piezo element PZT in the period T3. As a result, the sixth drive pulse PS6 is applied to the piezo element PZT, and about 1.5 pL of ink is ejected. In forming the medium dot, the first drive signal COM_A is applied to the piezo element PZT in the period T2. As a result, the second drive pulse PS2 is applied to the piezo element PZT, and about 3 pL of ink is ejected. In the formation of large dots, the second drive signal COM_B is applied to the piezo element PZT in the period T2. As a result, the fifth drive pulse PS5 is applied to the piezo element PZT, and about 7 pL of ink is ejected. In the formation of extra large dots, the first drive signal COM_A is applied to the piezo element PZT in the period T1, and the second drive signal COM_B is applied in the period T2. Accordingly, the first drive pulse PS1 and the fifth drive pulse PS5 are applied to the piezo element PZT, and about 14 pL of ink is ejected. In the maximum dot formation, the first drive signal COM_A is applied to the piezoelectric element PZT in the period T1 and the period T3, and the second drive signal COM_B is applied in the period T2. As a result, the first drive pulse PS1, the third drive pulse PS3, and the fifth drive pulse PS5 are applied to the piezo element PZT, and about 21 pL of ink is ejected.

  There are four types of black and yellow dot formation data SI (2-bit command gradation value) corresponding to each of no dot, small dot formation, medium dot formation, and large dot formation. In this case, the switch operation information is determined as follows. That is, the switch operation information for the first switch 79 corresponding to no dot (command gradation value [00]) is data [000], and the switch operation information for the second switch 80 is data [100]. . The switch operation information for the first switch 79 corresponding to the formation of small dots (command gradation value [01]) is data [010], and the switch operation information for the second switch 80 is data [000]. . The switch operation information for the first switch 79 corresponding to the formation of medium dots (command gradation value [10]) is data [000], and the switch operation information for the second switch 80 is data [010]. . The switch operation information for the first switch 79 corresponding to the formation of large dots (command gradation value [11]) is data [101], and the switch operation information for the second switch 80 is data [010]. . The meanings of the upper bits, middle bits, and lower bits of each switch operation information are as described above.

  Accordingly, in each of the black and yellow inks, each drive pulse is applied to the piezo element PZT in the pattern shown in FIG. 13B. That is, when there is no dot, the fourth drive pulse PS4 is applied to the piezo element PZT, and the meniscus is slightly vibrated. In the formation of small dots, the second drive pulse PS2 is applied to the piezo element PZT, and about 3 pL of ink is ejected. In forming the medium dot, the fifth drive pulse PS5 is applied to the piezo element PZT, and about 7 pL of ink is ejected. In forming the maximum dot, the first drive pulse PS1, the third drive pulse PS3, and the fifth drive pulse PS5 are applied to the piezo element PZT, and about 21 pL of ink is ejected.

  Incidentally, in the black and yellow controller units CU (K) and CU (Y), the upper input terminal SI_U is connected to the ground. For this reason, the dot formation data SI_K and SI_Y for black and yellow are handled in the same way as 3-bit data in which data [0] is added to the most significant bit. That is, when viewed as 3-bit data, yellow and black dot formation data SI_K and cyan and magenta dot formation data SI have the same contents when the same amount of ink is ejected. As a result, the head-side controller HSC (each controller unit CU (C) to CU (K)) can handle these data without distinction, and simplifies the control.

<Summary>
As described above, the image processing circuit 58 serving as a command gradation value output unit has a command of 2 bits (corresponding to a predetermined number of bits) for each ink of black and yellow (corresponding to a certain color). A gradation value (corresponding to the first command gradation value) is output. For each ink of cyan and magenta (corresponding to other colors), a 4-bit command gradation value (corresponding to the second command gradation value) is output. Then, the 6 gradation conversion section 64 as the instruction gradation value conversion section is 4 bits when discharging the amount of ink (for example, 3 pL, 7 pL, 21 pL) that can be discharged in black and yellow colors in cyan and magenta. The content of the lower 2 bits in the command gradation value is converted to the same content as the 2-bit command gradation value. This makes it possible to share ink discharge control when the ink amounts that can be discharged in black and yellow are discharged in cyan and magenta. That is, the same control can be performed based on the contents of the common part (lower 2 bits). In this example, 2 bits are shared from the least significant bit. For this reason, it is possible to recognize the bit to be shared with the least significant bit as a reference. Therefore, control becomes easy.

  Further, the image processing circuit 58 sets the data other than the lower 2 bits in the 4-bit command gradation value as data [0] when the ink amounts that can be ejected in black and yellow are designated in cyan and magenta. . That is, the upper 2 bits are set to data [00]. Thereby, the 4-bit command gradation value shows the same value as the 2-bit command gradation value, although the number of bits is different. Therefore, cyan and magenta ink ejection control can be easily aligned with black and yellow ink ejection control.

  Further, the image processing circuit 58 sets any bit other than the lower 2 bits in the 4-bit command gradation value when an ink amount other than the ink amount that can be ejected in black and yellow is designated in cyan and magenta. Data [1]. Specifically, the bit that is one bit higher than the lower two bits is used as data [1]. Then, based on the fact that any bit other than the lower 2 bits is data [1], it is identified that the command gradation value discharges an ink amount other than the ink amount that can be discharged in black and yellow. it can. As a result, control can be facilitated. In addition, since the bit that is one bit higher than the lower two bits is set to data [1], six gradations can be expressed by three-bit data. That is, the number of bits of the command gradation value to be used can be reduced as much as possible.

  Further, in this multifunction device 1, the number of bits of the command gradation value used for cyan and magenta is larger than the number of bits of the command gradation value used for black and yellow. Prints with fine density. Thereby, color reproducibility can be improved.

=== Other Embodiments ===
In the above-described embodiment, the six gradation conversion unit 64 provided in the multifunction machine 1 has been described. This description includes a description of the printing apparatus, a computer program for controlling the printing apparatus, and codes. Further, this embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the 6 gradation conversion unit 64>
In the first embodiment described above, the 6 gradation converter 64 is provided in the main controller 7. However, it is not limited to this configuration. For example, as shown in FIG. 14, a 6-gradation conversion unit 64 and a data conversion unit may be provided in the head-side controller HSC. The configuration in which the 6-gradation conversion unit 64 is provided in the main controller 7 has an advantage of easy mounting. This is because the main controller 7 is disposed on the main body side having a larger size than the head unit HU. On the other hand, when the 6 gradation converter 64 is provided in the head-side controller HSC, the distance (the length of the wiring) between the 6 gradation converter 64 and each controller unit CU is determined so that the 6 gradation converter 64 is the main. It becomes shorter than the case where it is provided in the controller 7. Therefore, the converted dot formation data SI (command gradation value) can be made less susceptible to noise.

<About dot gradation>
In the embodiment described above, the dot gradation is 4 gradations (2 bits) for black ink and yellow ink, and 6 gradations (3 bits) for cyan ink and magenta ink. The dot gradation is not limited to this combination. In this case, the combination of ink colors is preferably determined according to the degree of color change with respect to the ink amount. For example, the yellow ink has a smaller change in color with respect to the ink amount than other colors, and the cyan ink and magenta ink have a greater change in color with respect to the ink amount than other colors. The black ink has a greater degree of color change with respect to the ink amount than the yellow ink. For this reason, yellow ink may have 4 gradations, and other inks may have 6 gradations.

<Regarding the command gradation value>
In the above-described embodiment, the command gradation value is output from the image processing circuit 58. That is, the image processing circuit 58 functions as a command gradation value output unit. By the way, the command gradation value may be output by a device connected to the multifunction device 1 (printing apparatus). For example, it may be output from the host computer CP. In this case, the host computer CP functions as a command gradation value output unit by executing a printer driver (a kind of computer program). That is, 256 gradation RGB image data is converted into 4 gradation or 6 gradation image data (command gradation value group) by executing a printer driver. Then, this image data is transmitted to the multi function device 1 (ASIC 51). Even with such a configuration, the same effects as those of the above-described embodiment can be obtained.

  In the above-described embodiment, there are two types of designated gradation values consisting of 4 gradations and 6 gradations, but there are 3 or more kinds such as 4 gradations, 6 gradations, and 8 gradations. May be.

FIG. 2 is a perspective view illustrating an external appearance of the multifunction machine. 1 is a block diagram illustrating a configuration of a multifunction machine. It is a figure explaining a printing mechanism. FIG. 4A is a cross-sectional view of the head. FIG. 4B is a view of the head as viewed from the nozzle side. FIG. 5A is a block diagram illustrating a configuration of a control unit included in the ASIC. FIG. 5B is a block diagram illustrating a configuration of a head control unit included in the control unit. It is a figure explaining the structure of one RAM which comprises a 1st RAM group and a 2nd RAM group. FIG. 7A is a conceptual diagram illustrating the relationship between the first and second RAM groups and the six gradation conversion unit. FIG. 7B is a conceptual diagram illustrating the functions of the first six gradation conversion unit and the second six gradation conversion unit. FIG. 8A is a diagram illustrating the relationship between the pre-conversion command tone value and the post-conversion command tone value. FIG. 8B is a diagram for explaining command gradation values of four gradations. It is a figure explaining the content of the signal line group between heads, and the signal transmitted. FIG. 10A is a diagram for explaining the contents of transmission data. FIG. 10B is a diagram illustrating cyan transmission data for the nth dot. It is a figure explaining a plurality of controller units which a head has. FIG. 12A is a block diagram illustrating a configuration of a cyan controller unit. FIG. 12B is a diagram for explaining the contents of data input to the upper side input terminal and the lower side input terminal of each controller unit. FIG. 13A is a diagram illustrating a first drive signal and a second drive signal generated by the drive signal generation unit. FIG. 13B is a diagram for explaining the drive pulse applied to the piezo element and the amount of ink ejected. It is a figure for demonstrating other embodiment.

Explanation of symbols

1 MFP, 2 image reading mechanism, 3 printing mechanism, 4 drive signal generator,
5 card slots, 6 sensor groups, 7 main controller, 11 document table,
12 document table cover, 21 paper transport mechanism, 22 carriage moving mechanism,
23 platen, 24 transport roller, 25 paper discharge roller, 26 transport motor,
31 cases, 32 flow path units, 33 piezo element units,
34 Common ink chamber, 35 Pressure chamber, 36 Elastic film, 37 Island part,
38 piezo elements, 39 bonding substrate, 41 timing belt,
42 Carriage motor, 43 Guide shaft, 44 Drive pulley,
45 idler pulley, 46 linear encoder, 51 ASIC,
52 memory, 53 CPU, 54 external I / F, 55 card I / F,
56 control unit, 57 motor driver, 58 image processing circuit,
59 DAC value output unit, 60 head control unit, 61 write transmission control unit,
62 1st RAM group, 63 2nd RAM group, 646 gradation conversion part,
65 data selection unit, 71 first shift register, 72 second shift register,
73 third shift register, 74 first latch circuit, 75 second latch circuit,
76 third latch circuit, 77 control logic, 78 decoder,
79 1st switch, 80 2nd switch, S paper, CR carriage,
IC ink cartridge, HU head unit, HD head, Nz nozzle,
Nk black ink nozzle row, Ny yellow ink nozzle row,
Nc cyan ink nozzle row, Nm magenta ink nozzle row,
PZT piezo element, wiring board for HFC element, HSC head side controller,
CU controller unit, FC flexible cable,
SI_U upper side input terminal, SI_D lower side input terminal,
COM drive signal, COM_A first drive signal, COM_B second drive signal,
SS11 first waveform section, SS12 second waveform section, SS13 third waveform section,
SS21 first waveform section, SS22 second waveform section, SS23 third waveform section,
PS1 first drive pulse, PS2 second drive pulse, PS3 third drive pulse,
PS4 4th drive pulse, PS5 5th drive pulse, PS6 6th drive pulse,
MC memory card, IB internal bus, CP computer, HW external device

Claims (16)

(A) A command gradation value output unit that outputs a command gradation value corresponding to the amount of ink to be ejected,
A command gradation value output unit that outputs a first command gradation value having a predetermined number of bits for a certain color and outputs a second command gradation value having a number of bits larger than the predetermined number of bits for other colors; ,
(B) a command tone value conversion unit for converting the second command tone value;
When the amount of ink that can be ejected with a certain color is ejected with the other color, the content of the predetermined number of bits in the second command tone value is converted to the same content as the first command tone value A command gradation value conversion unit to perform,
A printing apparatus having (C). The printing apparatus according to claim 1,
The command gradation value converter is
A printing apparatus that converts the content of the predetermined number of bits from the least significant bit in the second command tone value to the same content as the first command tone value. The printing apparatus according to claim 1 or 2, wherein
The command gradation value converter is
A printing apparatus that sets the content of bits other than the predetermined number of bits in the second command gradation value to data [0]. The printing apparatus according to claim 3,
The command gradation value converter is
When the amount of ink other than the amount of ink that can be ejected with a certain color is ejected with the other color, the content of any bit other than the predetermined number of bits in the second command gradation value is data [1] A printing apparatus. The printing apparatus according to claim 3,
The command gradation value converter is
When the amount of ink other than the amount of ink that can be ejected with a certain color is ejected with the other color, the content of the bit that is one bit higher than the predetermined number of bits is set to data [1]. apparatus. The printing apparatus according to any one of claims 1 to 5,
The dot of a certain color is formed with a predetermined number of gradations based on the first command gradation value, and the dots of the other colors are larger than the predetermined number of gradations based on the second command gradation value. A printing apparatus having a head formed with another predetermined number of gradations. The printing apparatus according to claim 6,
The head is
An element that operates to eject the ink;
A head-side controller that performs control for operating the element based on the first command tone value and the second command tone value;
A printing apparatus. The printing apparatus according to claim 7, wherein
A printing apparatus having a cable for electrically connecting a main controller and the head-side controller. The printing apparatus according to claim 8, wherein
The command gradation value converter is
A printing apparatus provided in the main controller. The printing apparatus according to claim 7 or 8,
The command gradation value converter is
A printing apparatus provided in the head-side controller. A printing apparatus according to any one of claims 1 to 10,
The command gradation value output unit
Outputting the command gradation value in which a plurality of bits of data are made into one set;
For the certain color, a first command gradation value composed of a predetermined number of sets of data is output,
A printing apparatus that outputs a second command gradation value composed of another predetermined number of data for the other colors. The printing apparatus according to claim 11, wherein
The command gradation value output unit
The command gradation value is output as a set of 2-bit data,
For the certain color, a 2-bit first command gradation value composed of a set of data is output,
A printing device that outputs a 4-bit second command gradation value composed of two sets of data for the other colors. A printing apparatus according to any one of claims 1 to 12,
The certain color is
Black and yellow,
The other colors are:
Printing devices that are cyan and magenta. (A) A command tone value output unit that outputs a command tone value in which 2-bit data is set as one set according to the amount of ink to be ejected,
For a certain color, a 2-bit first command gradation value composed of one set of data is output, and for the other colors, four bits composed of two sets of data and larger than the predetermined number of bits. A command tone value output unit for outputting the second command tone value of
(B) a command tone value conversion unit for converting the second command tone value;
When the amount of ink that can be ejected in a certain color is ejected in the other color, the content of the predetermined number of bits from the least significant bit in the second command tone value is referred to as the first command tone value. While converting to the same content, the content of bits other than the predetermined number of bits in the second command gradation value is set to data [0], and the amount of ink other than the amount of ink that can be ejected with the certain color is set. When discharging in the other color, the contents of the bits other than the predetermined number of bits in the second command gradation value and one bit higher than the predetermined number of bits are set to data [1]. A command gradation value conversion unit;
(C) The dot of a certain color is formed with a predetermined gradation number based on the first command gradation value, and the dot of the other color is formed with the predetermined gradation number based on the second command gradation value. A head that is formed with a different number of gradations than
A head having an element that operates to discharge the ink, and a head-side controller that performs control to operate the element based on the first command gradation value and the second command gradation value; ,
(D) a cable for electrically connecting the main controller and the head-side controller;
Have
(E) The command gradation value conversion unit
Provided in either the main controller or the head-side controller,
(F) The certain color is
Black and yellow,
(G) The other colors are:
Printing devices that are cyan and magenta. (A) A first command gradation value having a predetermined number of bits for a certain color and a second command gradation value having a number of bits larger than the predetermined bit number for other colors according to the amount of ink to be ejected. Output each
(B) When the amount of ink that can be ejected with a certain color is ejected with the other color, the content of the predetermined number of bits in the second command tone value is the same as the first command tone value Converting to content,
Do the printing method. (A) A program for controlling a printing apparatus,
(B) A first command gradation value having a predetermined number of bits for a certain color and a second command gradation value having a number of bits larger than the predetermined number of bits for other colors according to the amount of ink to be ejected. Output each
(C) When the amount of ink that can be ejected in a certain color is ejected in the other color, the content of the predetermined number of bits in the second command tone value is the same as the first command tone value Converting to content,
(D) forming the dot of the certain color based on the first command gradation value, and forming the dot of the other color based on the second command gradation value;
A program for causing the printing apparatus to perform the operation.

Images