JP4027358B2 - Ink jet head and ink jet recording apparatus using the head - Google Patents

Description

  The present invention relates to an ink jet head and an ink jet recording apparatus using the head, and in particular, an ink jet head in which a plurality of head chips are arranged in a direction orthogonal to a conveyance direction of a recording material to form an ejection port array and the head. The present invention relates to the ink jet recording apparatus used.

  Recording devices used in printers, copiers, etc., or recording devices used as output devices such as composite electronic devices and workstations including computers and word processors are used for recording materials such as paper and plastic thin plates based on recorded information. An image (including characters and symbols) is recorded.

  As a recording head used in such a recording apparatus, there is a so-called full multi-type ink jet head. In a full multi-type recording head, the terminology generically refers to nozzles (unless otherwise specified, ink ejection openings, liquid paths communicating with the nozzles, and elements that are arranged in the liquid paths and generate energy used for ejection). In some cases, it has been difficult to perform a process that provides a wide range of defects such as the entire width of the recording area. For example, in a printer that performs photo-like output on large format paper such as materials output in an office etc., considering the case of recording at 1200 dpi on an A3 size paper with a recording width of about 280 mm, the range is within that range. About 14,000 discharge ports are required. Machining the nozzle without a single defect corresponding to such a large number of discharge ports makes the manufacturing process extremely difficult, and even if manufactured, the yield rate is low and the manufacturing cost is enormous. turn into.

  Therefore, as a full multi-type ink-jet head, a plurality of relatively inexpensive short chips used in serial-type recording devices are arranged with high precision so that they are long enough to meet the desired length. (Referred to as tethering head) has been devised.

  FIG. 17 is a schematic diagram showing a configuration example of such an inkjet head. In the inkjet head IH, head chips HC, which are numbered sequentially from the first, are arranged in two rows in a staggered pattern in the Y direction (recording material). They are arranged extending in the direction perpendicular to or intersecting the transport direction. Adjacent numbered head chips HC are arranged so as to have a connecting portion where a predetermined number of ejection ports located at the end overlap. In order to realize color recording using the connecting head IH having such a configuration, four colors of cyan (C), magenta (M), yellow (Y), and black (Bk) are supported in the same chip. Possible by arranging staggered head chips HC in which the ejection port arrays NAC, NAM, NAY, and NABk are arranged in the recording material conveyance direction, which is the X direction in the figure, along a direction orthogonal to or intersecting the recording material conveyance direction It becomes.

  In any of the ink jet heads having this configuration, all the ink color ejection openings are overlapped at the same place on the line in the recording material conveyance direction at the connection portion of each head chip. For this reason, when an image is formed by discharging onto a recording material, the overlap for all ink colors at the joint portion coincides with the line in the recording material conveyance direction, and the conveyance direction of the recording material P is formed on the formed image. The dark-colored “Tsunagi-suji” that extends to

  Therefore, as shown in FIG. 18, in the connecting portion, the ejection port arrays for the respective color inks are arranged shifted in the Y direction on the same head chip, and the ejection ports for the same color ink are arranged between the head chips in the recording material conveyance direction. A configuration in which the inkjet head is arranged so as not to be positioned on the line is considered (see Patent Document 1).

  However, in the configuration shown in FIG. 18, there is no overlap of the same color ink ejection ports on the line in the recording material conveyance direction between the head chips, and therefore, “joining lines” (“white lines”) in this part is a problem. There is a case. As an example, there is a so-called “end-to-end” problem as described in Patent Document 2. This “edge shift” means that when an image with a high recording duty is recorded at a high speed in a state where fine discharge ports are arranged, the ink discharge direction from the discharge port located on the end side is the inner side of the discharge port array. (In FIG. 18, this means that the end of the head chip HC (n-1) is moved in the YR direction, and the end of the head chip HC (n) is moved in the YL direction (n is an integer). )), A phenomenon in which the landing position of the discharged ink does not face the discharge port. When the connecting head is configured, white streaks occur along the recording material conveyance direction in the recording portion corresponding to the connecting portion between the head chips.

As a countermeasure against this problem, the following method described in Patent Document 3 can be cited.
As shown in FIG. 19, at the connecting portion between the head chip HC (n-1) and the head chip HC (n), the ink discharge ports on the line in the recording material transport direction are at least different from other ink discharge ports of the same color. The head chips are arranged so as to overlap one or more, and one of the overlapping discharge ports is selected, and data thinning is performed so as to handle the recording of the line (same raster) in the conveyance direction of the recording material P. . Accordingly, in the configuration of FIG. 19, the recording duty for each ejection port at the joint between the end portions of the head chip can be halved, and as a result, the edge can be relaxed.

JP 2000-289233 A JP 2002-67320 A Japanese Patent Laid-Open No. 5-57965

  However, the present inventors have found that the following problem is newly generated when the configuration of FIG. 19 in which the ejection openings of the same color are partially overlapped between the head chips is actually used. This has been found to occur particularly when one-pass recording (recording by one relative scanning of the inkjet head with respect to the same recording area on the recording medium) is performed using the head having the configuration shown in FIG. It was.

  As shown in FIG. 20, it is assumed that the recording material P is conveyed from the cyan ejection port array NAC side of the inkjet head or head chip HC to the black ejection port array NABk side (X direction). At this time, since it is one-pass printing, ink is always recorded in the order of cyan, magenta, yellow, and black at the non-joint portion where the ejection openings for the same color ink do not overlap on the line in the recording material conveyance direction (X direction). Land on material P. On the other hand, since the discharge ports for the same color ink overlap on the line in the recording material conveyance direction at the joint portion, for example, depending on the data thinning mode, for example, cyan ink dots are formed and other color inks are formed. Contrary to this, there are cases where dots are attached, or on the contrary, cyan ink dots are attached after ink dots of other colors are formed.

  In ink jet recording, even if two colors of ink are landed at the same position, it is known that two colors different from human visual characteristics are expressed depending on the order of ink ejection. Therefore, when the landing order is different, a difference in color occurs between the connection portion and the non-connection portion, and this appears as “color unevenness” at the connection portion.

  An object of the present invention is to eliminate the “connection streaks” caused by the discharge ports for each color between the head chips constituting the connection head overlapping on the line in the recording material conveyance direction. It is an object of the present invention to provide an ink jet head and an ink jet recording apparatus in which no streak is generated and no “color unevenness” is generated in the joint portion due to the difference in the landing order of the inks of the respective colors.

Therefore, the present invention is an inkjet head in which a plurality of head chips having at least two rows of ejection opening arrays corresponding to at least two color inks are arranged in a staggered manner along the direction of the ejection opening array,
In the head chip, the use range of the discharge ports used for the recording operation is different between the at least two rows of discharge port arrays, and the relationship between the two adjacent head chips arranged in a staggered manner is as follows. At least one ejection port corresponding to ink of the same color tone at the end overlaps in the relative movement direction of the recording material and the inkjet head, and does not overlap in the relative movement direction of the ejection port of different color tone. The plurality of head chips are arranged with conditions.

  The present invention also relates to an ink jet recording apparatus that performs recording using such an ink jet head and includes a mechanism for transporting a recording material so as to move relative to the ink jet head.

  In this specification, “record” is not only formed when significant information such as characters and figures is formed, but also manifested so that human beings can perceive it visually. Regardless of whether or not, an image, a pattern, a pattern, or the like is widely formed on a recording material, or a medium is processed.

  In addition, “recording material” refers to not only paper used in general ink jet recording apparatuses, but also materials that can accept ink ejected by a head, such as cloth, plastic film, metal plate, and the like. And

  Further, the term “ink” should be broadly interpreted in the same way as the definition of “recording”, and is applied to the recording material to form images, patterns, patterns, etc., or to process the recording material. Shall refer to the liquid that can be made.

  According to the present invention, when one-pass printing is performed using a connection head in which head chips capable of ejecting two or more different colors on the same head chip are connected in a staggered arrangement, the connection by overlapping the connection portions of the respective colors is performed. High-quality recording can be performed in which the generation of streaks is prevented and there is no occurrence of color unevenness due to the difference in the landing order of the ink droplets at the connecting portion of each color and the white streaks due to the edge.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic perspective view showing a schematic configuration of an ink jet recording apparatus applied to an embodiment of the present invention.

  The ink jet recording apparatus 1 of the present embodiment is a full line type in which long ink jet heads 2A and 2B extending in a direction Y orthogonal to or intersecting with the transport direction X of the recording material P are arranged in parallel in the X direction. The color ink jet recording apparatus. The ink-jet head 2A includes a head chip having a cyan ink ejection port array and a magenta ink ejection port array, which are arranged over a predetermined range in a direction orthogonal to the conveyance direction of the recording material P. The recording material P is arranged in a staggered manner in a direction orthogonal to the conveyance direction of the recording material P so that the recording of the entire width of the recording material P in the Y direction is possible. Thus, a connecting head is configured that can perform a recording operation corresponding to the width of the recording material P in the Y direction. The inkjet head 2B has the same configuration as the inkjet head 2A with respect to yellow ink and black ink.

  The ink jet head 2A is connected to ink tanks 3C and 3M storing cyan ink and magenta ink, respectively, and the ink jet head 2B is connected to ink tanks 3Y and 3Bk storing yellow ink and black ink, respectively, via connection piping 4. Receive ink. In each ink jet head, an ink supply path is distributed to each head chip.

  In the following description, the inkjet heads 2A and 2B are collectively referred to as the inkjet head 2 unless there is a need for distinction. Further, the four ink tanks 3Y, 3M, 3C, and 3Bk are collectively described as the ink tank 3 unless there is a need for distinction.

  The ink jet heads 2A and 2B can be moved up and down (moved in a direction approaching or separating from the recording material) by a head moving means 10 whose operation is controlled by the control device 9. . Further, on the side of the ink jet heads 2A and 2B, prior to the recording operation on the recording material P, the thickened ink or the like intervening in the ink flow path communicating with each discharge port is discharged from the discharge port to perform ink jetting. A head cap 7 for performing head recovery processing is disposed. The conveying belt 5 that conveys the recording material P is stretched over a driving roller connected to a belt driving motor 11, and its operation is switched by a motor driver 12 a connected to the control device 9. Further, on the upstream side of the conveying belt 5, as an additional configuration, a charger 13 for bringing the recording material P into close contact with the conveying belt 5 by charging the conveying belt 5 can be provided. The charger 13 is turned on / off by a charger driver 12b connected to the control device 9. A pair of feeding rollers 14 and 14 for supplying the recording material P onto the conveying belt 5 is connected to a feeding motor 15 for driving and rotating the pair of feeding rollers 14 and 14. The operation of the feeding motor 15 is switched by a motor driver 16 connected to the control device 9. Therefore, when performing a recording operation on the recording material P, the charging belt 13 is operated and the conveying belt 5 is driven at the same time, and the recording material P is placed on the conveying belt by the paper feed rollers 14 and 14. Then, a color image is recorded on the recording material P by each inkjet head 2. Reference numeral 2a denotes a head driver for controlling the heater driving described below by an on / off signal.

  Next, the configuration of the head chip applied to the ink jet head used in the present embodiment and the basic ink ejection operation will be described.

FIG. 2 shows a configuration example of the head chip.
The head chip 55 generally includes a substrate (heater board) 104 formed with a plurality of heaters 102 for generating thermal energy that causes film boiling in the ink as energy used for ejecting the ink. The top board 106 joined on the heater board 104 is comprised. A plurality of discharge ports 108 are formed in the top plate 106, and a tunnel-like liquid that communicates with the discharge ports 108 and is separated from the adjacent liquid passage 110 by a partition 112 at the rear of the discharge ports 108. A groove for forming the path 110 is provided. Each liquid passage 110 is provided with a heater 102 and is commonly connected to one liquid chamber 114 at the end opposite to the discharge port. The liquid chamber 114 is supplied with the ink received and distributed from the ink tank 3 through the ink supply port 116, and the ink is further supplied from the liquid chamber 114 to the respective liquid paths 110. The heater board 104 and the top plate 106 are aligned and assembled so that each heater 102 is in an appropriate position corresponding to each liquid passage 110, and become a head chip. Then, when a predetermined drive pulse is supplied to the heater 102 in the assembled state as shown in FIG. 2, film boiling occurs in the ink on the heater 102 to form bubbles, and the ink expands to the discharge port by the volume expansion of the bubbles. The ejection is carried out by being pushed out from 108.

  FIG. 2 shows a configuration in which a heater having a main plane in a direction substantially parallel to the ink ejection direction is employed, and a head chip or inkjet head having such a configuration is called an edge shooter type.

  In contrast to this, FIG. 3 shows a configuration in which a heater having a main plane in a direction substantially perpendicular to the ink ejection direction is employed, and the head chip or inkjet head having such a configuration is referred to as a side shooter type. It is what is done.

  In this configuration, the heater 202 is arranged at a position facing the discharge ports 208 arranged in a direction perpendicular to the drawing. The heater board 204 is formed by forming the heater 202 and the electrode wiring electrode wiring for supplying electric power thereto on the surface of the substrate made of silicon or the like. The heater board 204 is joined with a discharge port 208 and a discharge port forming member 206 provided with an ink flow path 203 communicating therewith. In order to supply ink to the flow path 203, an ink supply path 214 is formed in the heater board 204.

  A head chip can be obtained by appropriately aligning and assembling the heater board 204 and the discharge port forming member 206. When a predetermined driving pulse is supplied to the heater 202 in the assembled state as shown in FIG. 3, film boiling occurs in the ink on the heater 202 to form bubbles, and the ink expands to the ejection port 208 by the volume expansion of the bubbles. The liquid is ejected by being pushed out from.

  The drive pulse (heat pulse) supplied to the heater can have the waveform shown in FIG. FIG. 4A shows a simple single pulse waveform having a voltage V over a period (pulse width) T. FIG. On the other hand, FIG. 4B shows a pulse waveform of a double pulse, T1 is a pulse width of a first pulse (pre-pulse) divided into a plurality (two), T2 is an interval time (pause period), T3 is the pulse width of the second pulse (main pulse). In the waveform of FIG. 4B, the ejection amount modulation can be performed by appropriately modulating the divided pulse and the interval time. These waveforms can be appropriately selected as desired.

  FIG. 5 shows a configuration example of a main part of a control system of the ink jet recording apparatus according to the present embodiment. In the figure, reference numeral 801 denotes a CPU that controls the entire system, and corresponds to the control device of FIG. A ROM 802 stores a system control program executed by the CPU 801 and other fixed data. A conveyance unit 803 conveys a recording material (such as paper or an OHP film), and includes a belt driving motor 11 and a motor driver 12a, a feeding motor 15 and a motor driver 16, and the like. Reference numeral 804 denotes a discharge recovery unit that recovers the head, and includes a head cap 7 and a cap moving means 8. Reference numeral 805 denotes a head moving unit, which includes a carrier and a head moving means for mounting the ink jet head to perform a required movement.

  Reference numeral 807 denotes a drive circuit that performs drive control of the heater of the inkjet head 2, and corresponds to the head driver 2a. Reference numeral 808 denotes a binarization circuit that converts an image to be recorded into ejection data, and performs a halftoning process and the like. Reference numeral 809 denotes an image processing unit that performs color separation according to the ink color of the inkjet head 2 when an image to be recorded (for example, an image received from a host device (not shown) such as a computer) is a color image.

  Reference numeral 810 denotes a circuit that selects a nozzle (actually used nozzle) that is actually used to perform a discharge operation in accordance with a head chip or an ink jet head configured as described below. That is, the actual use nozzle selection circuit 810 appropriately determines a nozzle to be actually used from the nozzles (ink discharge ports) even if the nozzle (ink discharge port) is physically present, and performs a required recording with respect to the actual use nozzle. It functions to transfer data to the drive circuit 807. That is, the present embodiment is an example in which the actual use nozzle is selected by an electrical signal.

  FIG. 6 is a configuration example of the ink jet heads 2A and 2B of the present embodiment, and schematically shows a state in which the ejection port arrangement surfaces of the heads are viewed. In this example, head chips each having a row of cyan ink ejection ports and a row of magenta ink ejection ports arranged in a predetermined range in a direction orthogonal to the conveyance direction of the recording material P are staggered. The inkjet head 2A in the form of a connecting head arranged in the above and the inkjet head 2B having the same configuration as the inkjet head 2A with respect to the yellow ink and the black ink are arranged side by side so that a color image using four colors can be recorded. Further, the black circle discharge port is a discharge port that is actually used, and the white circle discharge port is a discharge port that is not used for actual recording. At the connecting portion between the head chips, two or more discharge ports overlap each other on the line in the recording material conveyance direction (X direction) in the Y direction discharge ports arranged at the end. And the connecting portion of the ink jet head 2B do not overlap in the X direction, and the connecting portion in the transport direction of the recording material P due to the overlap of the discharge ports of the connecting portions of all colors does not occur. It is.

  That is, this embodiment can achieve the intended purpose by preventing white streaks and color unevenness at the head chip joints in each head. The configuration on the inkjet head 2A side will be described as an example.

  FIG. 7 is a diagram showing the arrangement of head chips and ejection openings in the inkjet head 2A, FIG. 8 is an enlarged view of the joint portion of the head chips, and FIGS. 9A and 9B show the contents of the selection data of the actually used nozzles. It is explanatory drawing shown.

  In the following description, the X direction exemplifies the recording material conveyance direction. However, as a configuration capable of exhibiting the effects of the invention, the X direction is “inkjet recording during ink ejection”. The direction in which the head and the recording material move relative to each other is defined. That is, in the so-called full-line type recording apparatus, the X direction is the recording material conveyance direction, and in the so-called serial type recording apparatus, the X direction is the scanning direction of the inkjet head. The Y direction is a direction that intersects the X direction at that time, but is a direction that is substantially orthogonal.

  First, in FIG. 7 and FIG. 8, white circles represent non-use nozzles and black circles represent actual use nozzles, and apparently four discharge ports overlap on the same line in the X direction with respect to the Y direction. However, for the cyan discharge port array NAC of the head chip HC (n-1), the two discharge ports at the ends in the YL direction are not used, and these discharge ports are for cyan of the head chip HC (n). Corresponding to the third and fourth discharge ports (actually used nozzles) from the YR direction end of the discharge port array NAC, and located on the line in the X direction, which is the recording material conveyance direction. Further, regarding the magenta discharge port array NAM of the head chip HC (n), the two discharge ports at the ends in the YR direction are not used, and these discharge ports are for magenta of the head chip HC (n-1). Corresponding to the third and fourth discharge ports (actually used nozzles) from the end in the YL direction of the discharge port array NAM, and located on the line in the X direction, which is the recording material conveyance direction. That is, the actual use nozzles of the same color have two discharge ports overlapping in the X direction at the connecting portion of the head chip, but there is no overlap in the X direction of the actual use nozzles between adjacent discharge port arrays of different colors.

  Further, regarding the cyan discharge port array NAC of the head chip HC (n), the two discharge ports at the ends in the YR direction in the figure are actually used nozzles. In the n-1) cyan discharge port array NAC, the nozzles are distributed to the third and fourth discharge ports (actually used nozzles) from the end in the YL direction. Similarly, regarding the magenta discharge port array NAM of the head chip HC (n−1), the two discharge ports at the ends in the YL direction are actually used nozzles. The magenta discharge port array NAM of (n) is distributed to the third and fourth discharge ports (actually used nozzles) from the end in the YL direction.

  By performing such distribution, it is possible to reduce the recording duty at the end of each head chip, and thus it is possible to prevent the occurrence of white streaks due to the edge twist phenomenon.

  Further, in the case where different color ink dots are overlapped, the end of each head chip end in the YR direction of the ejection port array NAC of the head chip HC (n) in the process of transporting the recording material in the X direction in the figure. Are discharged from the third and fourth discharge ports from the end in the YL direction of the discharge port array NAC of the head chip HC (n-1). Discharge is performed from the third and fourth discharge ports from the end in the YL direction of the discharge port array NAM. After discharging from the third and fourth discharge ports from the YR direction end of the discharge port array NAM of the head chip HC (n), from the YR direction end of the discharge port array NAM of the head chip HC (n) The discharge is performed from the third and fourth discharge ports or the two discharge ports at the end in the YL direction of the discharge port array NAM of the head chip HC (n-1).

  That is, the ink landing order is always the order of cyan and magenta also at the end of each head chip. Therefore, even if the above-described data distribution is performed, it is possible to suppress the color change at the connecting portion.

  With reference to FIGS. 9A and 9B, a mode of determining the actual use nozzle and the non-use nozzle as described above with respect to the physical discharge port or nozzle arrangement will be described.

  FIGS. 9A and 9B show the contents of the selection data of the actually used nozzle for the arbitrary head chip HC (n) for cyan and magenta and the head chip HC (n−1) to be connected, respectively. It is explanatory drawing shown, and it is assumed that m nozzles are physically arranged on the head chip from number 1 to m (m is an integer).

  In the table, “1” corresponds to data meaning actual use and “0” means non-use. In the setting shown in FIG. 9A, for the cyan nozzle array NAC, all nozzles 1 to m are actually used nozzles. For the magenta nozzle array NAM, the numbers 3 to m-2 are actually used nozzles, and a total of 4 nozzles, 2 nozzles at both ends, actually exist and have an ink ejection function. It is not used at runtime. In the setting shown in FIG. 9B, the actual use nozzles are reversed with respect to cyan and magenta.

  These selection data can be provided as fixed data in the ROM 802, for example. Further, it may be appropriately set in a RAM, an EEPROM or the like according to the configuration of the head.

  FIG. 10 shows an example of a circuit configuration for individually controlling the heater of each nozzle using such selection data of the actually used nozzles. Specifically, this circuit can be built in a heater board in a semiconductor manufacturing process.

  In FIG. 10, a signal line VH is a power supply line of the inkjet head connected to one terminal of the heater HTR, and a signal line HGND is a ground connected to the other terminal of the heater HTR via an on / off switching transistor TR. Line. The signal line MH is a heat pulse signal line and is connected to one input terminal of the AND gate AND. The signal line DATA is a data line for serially transferring recording data (data for determining ejection / non-ejection) corresponding to each nozzle to the shift register SR. The signal line DLAT is a control line for latching recording data arranged in the shift register SR corresponding to the nozzles in the latch circuit LAT at an appropriate timing, and its output (heater ON / OFF signal) is the AND circuit AND. Connected to the other input end.

  When the data of all nozzles is gathered in the shift register, the DLAT signal is generated and the data is latched. The heater ON signal becomes valid during the heat pulse by the AND circuit AND, and the transistor TR is turned on to turn on the heater HTR. Is energized. Along with this, the ink is heated and foamed, and the ink is ejected from the ejection port.

  In this configuration, the print data can be assigned in advance to the corresponding nozzles by sending data for determining the actual use nozzles by the actual use nozzle selection circuit 810 to the image processing unit 809. Further, in the circuit configuration of FIG. 10, the heater ON / OFF signal is selected from the selection signal line of the actually used nozzle, and an AND circuit that takes the logical product of the signal and the ON / OFF signal is provided on the circuit side of FIG. It may be added.

  The configuration of the cyan and magenta ink head 2A has been described above, but the same configuration is applied to the yellow and black ink head 2B.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and various configurations can be adopted, and some of them will be exemplified below.

  For example, in the first embodiment, the inkjet head 2A in which the discharge port arrays for cyan ink and magenta ink are configured on the same chip, and the inkjet in which the discharge port arrays for yellow and black ink are configured on the same chip. Although the configuration using the head 2B is used, an inkjet head in which the discharge port arrays for these four colors are configured on the same chip may be used.

  Further, FIG. 11 shows a configuration example in which two inkjet heads are used as in the first embodiment, but only yellow is a connecting portion and does not overlap on a line in the recording material conveyance direction (X direction) of the ejection port. is there.

  In FIG. 12, two inkjet heads are used as in the first embodiment. However, the discharge port is connected to the black ink discharge port array on the line in the recording material conveyance direction (X direction). It is the example of a piled up structure. These are arrangements in consideration of the optical density characteristics of the ink. That is, for example, yellow can be configured as shown in FIG. 11 by utilizing the phenomenon that “yellow stripes or color irregularities are generally difficult to visually recognize due to low optical density”. It is. However, when a secondary color or tertiary color using yellow is taken into consideration, there is no overlap in the X-direction line with the discharge ports of other colors in the connecting portion including yellow, and at least 1 is required for the discharge ports of the same color. Needless to say, a configuration in which two or more discharge ports are stacked on the X-direction line is desirable.

  Furthermore, in 1st Embodiment, although it was set as the structure which selects whether it uses with respect to the nozzle which exists physically, the structure which removed the unused nozzle beforehand (structure which does not manufacture a nozzle part applicable from the beginning) ) Is also possible. For example, as shown in FIG. 13, the nozzles for cyan and magenta can be configured such that unused nozzles are removed in advance. This can be realized by forming the nozzle itself on the chip.

  Further, two head chips are prepared by using a head chip in which an ejection nozzle array for four colors without an unused nozzle is arranged on the same chip as shown in FIG. 14, and as shown in FIG. A long head can also be configured by connecting them in a staggered manner in the Y direction. Although FIG. 14 shows a portion where two head chips are not connected, the number of head chips to be used is not limited to two, and a number of head chips can be used as needed.

  In the configuration in which the nozzles that actually exist are not used as in the first embodiment, depending on the number of unused nozzles, the concentration of the ink in the unused nozzles increases due to evaporation of the ink solvent or the like. It is conceivable that the ink wraps around the adjacent use nozzle and raises the ink density at that portion. From this point, it can be said that a configuration in which nozzles that are not actually used are removed in advance (a configuration that is not manufactured from the beginning) is more preferable. However, on the other hand, the first embodiment has an advantage that the number of ejection openings to be overlapped on a line in the recording material conveyance direction can be freely set. Therefore, regarding the problem that the ink density increases in the first embodiment, recovery processing such as preliminary ejection is performed on all the nozzles including the unused nozzles before the start of recording, thereby discharging the ink with the increased density. This can be dealt with by performing the processing to be performed.

  That is, whether to adopt a configuration in which only the actually used nozzles are selected from a nozzle group that physically exists or a configuration in which unused nozzles are removed in advance depends on the configuration of the apparatus using the inkjet head, the control mode, etc. It is possible to select a head having a form having advantages depending on a desired situation.

  In the above embodiment, the nozzle array of each color in the head chip is arranged in a row in the horizontal direction. However, it may be arranged in a plurality of rows.

  FIG. 15 shows a case where there are two nozzle rows for each of cyan and magenta in the head chip, and the nozzles themselves are also staggered. In other words, the nozzle resolution (inter-nozzle pitch) of one of the two rows is 600 dpi, and the other is also 600 dpi, so that the nozzle resolution corresponding to 1200 dpi is formed by shifting the pitch by half a pitch. FIG. 16 shows an example in which the nozzle chips are arranged in a staggered manner to form a long head, and the yellow and black inks have the same structure.

  Even in this case, it is possible to realize a head configuration that meets the object of the present invention, as in the above-described embodiments, by not using the end nozzle. Of course, the configuration in which the end nozzle is not used may be selected on an electric circuit as described above, or may be one in which the nozzle is removed in advance.

  Further, as a modification of the above configuration examples, a discharge nozzle is provided in an end nozzle that is not used, but a so-called dummy nozzle that does not have a discharge function (nozzle is built in, but discharge energy) It is also possible to use a nozzle having a configuration that cannot generate the above. This can be realized by not having a heater corresponding to the nozzle, or by forming a heater board in which no electrical connection is formed.

  In the above example, the overlap amount of the nozzles of the same color is set to two discharge ports. However, the number can be an appropriate number of one or more as long as the number of edges can be effectively prevented.

  Further, the above description has been made on an ink jet head using an element (heater) that generates thermal energy as energy used for ink ejection. However, other systems, for example, piezoelectric elements are used to eject ink using mechanical energy. Needless to say, the present invention can also be applied to an ink-jet head according to a method to be performed.

  In the above example, the configuration using a head chip or an ink jet head corresponding to four colors of cyan, magenta, yellow and black is exemplified. However, the type or color tone (color, density) of the ink is not limited to that. It is. That is, a configuration using light magenta or light cyan having a low density, or special color inks such as red, green, and blue may be used.

  In addition, in the above example, the case where the present invention is applied to a line printer in which ejection openings or head chips are arranged over a range corresponding to the width of the recording material has been described. However, in the serial type ink jet recording system in which the recording operation is performed by repeating the relative scanning of the ink jet head in a direction different from the arrangement direction of the discharge ports and the relative conveyance of the recording material in the direction orthogonal thereto. However, the present invention can be effectively applied to a configuration in which several head chips are arranged to achieve a desired length as a configuration of the inkjet head. Specifically, in FIG. 6, a serial type ink jet recording system in which an ink jet head is mounted on a carriage or the like in the X direction and scanned, and a recording material is repeatedly conveyed in a Y direction every predetermined length.

1 is a schematic perspective view showing a schematic configuration of an ink jet recording apparatus applied to a first embodiment of the present invention. It is a typical perspective view which shows the structural example of the principal part of a head chip. It is a typical sectional view showing other examples of composition of the principal part of a head chip. (A) And (b) is a wave form diagram which shows two examples of the pulse which drives the heater which generate | occur | produces the thermal energy utilized in order to discharge an ink. FIG. 2 is a block diagram illustrating a configuration example of a control system of the ink jet recording apparatus applied to the first embodiment of the present invention. It is a schematic diagram which shows the structural example of the two inkjet heads applied to the 1st Embodiment of this invention. It is a schematic diagram for demonstrating one structure of the inkjet head shown in FIG. It is a schematic diagram which expands and shows the connection part of the head chip which comprises the inkjet head of FIG. (A) And (b) is a schematic diagram for demonstrating the data for determining use / non-use of the nozzle in a head chip. It is a typical block diagram which shows the structural example of the circuit for driving the heater which generate | occur | produces the thermal energy utilized in order to discharge an ink. It is a schematic diagram which shows the structural example of the inkjet head applied to other embodiment of this invention. It is a schematic diagram which shows the structural example of the inkjet head applied to further another embodiment of this invention. It is a schematic diagram which shows the structural example of the inkjet head applied to another embodiment of this invention. It is a schematic diagram which shows the structural example of the principal part of the inkjet head applied to another embodiment of this invention. It is a schematic diagram which shows the structural example of the head chip of the inkjet head applied to the further embodiment of this invention. FIG. 16 is a schematic diagram illustrating an inkjet head that is configured by connecting the head chips of FIG. 15 and that is applied to a further embodiment of the present invention. It is a schematic diagram for demonstrating the long inkjet head of a prior art example comprised by connecting the short head chip corresponding to several colors. FIG. 18 is a schematic diagram for explaining a configuration for preventing splicing that occurs when recording is performed with the configuration of FIG. 17. FIG. 5 is a schematic diagram for explaining a problem when the head chips are arranged such that at least one or more ink discharge ports of the same color overlap at a connecting portion between the head chips. It is a schematic diagram for demonstrating the new problem which arises when the structure which solves the problem demonstrated in relation to FIG. 19 is taken.

Explanation of symbols

2A, 2B, IH Inkjet head 104, 204 Heater board 102, 202 Heater 106 Top plate 108, 208, EH Discharge port 206 Discharge port forming member 801 CPU
802 ROM
807 Drive circuit 809 Image processing unit 810 Actual use nozzle selection circuit HC head chip NA, NAC, NAM, NAY, NABk Discharge port array

Claims (7)

An inkjet head in which a plurality of head chips having at least two rows of ejection port arrays corresponding to at least two-color inks are arranged in a staggered manner along the direction of the ejection port array,
In the head chip, the use range of the discharge ports used for the recording operation is different between the at least two rows of discharge port arrays, and the relationship between the two adjacent head chips arranged in a staggered manner is as follows. At least one ejection port corresponding to ink of the same color tone at the end overlaps in the relative movement direction of the recording material and the inkjet head, and does not overlap in the relative movement direction of the ejection port of different color tone. An ink jet head characterized in that the plurality of head chips are arranged under certain conditions.   The inkjet head according to claim 1, wherein the head chip has an ejection port array corresponding to ink of a predetermined color tone that does not comply with the condition.   The inkjet head according to claim 2, wherein the ink of the predetermined color tone is an ink having a low optical reflection density.   The inkjet head according to claim 1, wherein an ejection port used for the recording operation is selected from the ejection port array according to a setting.   The inkjet head according to claim 1, wherein only the ejection ports used for the recording operation are arranged in advance.   An inkjet recording apparatus that performs recording using the inkjet head according to claim 1, further comprising a mechanism that conveys a recording material so as to move relative to the inkjet head. Inkjet recording device.   7. The ink jet recording apparatus according to claim 6, further comprising means for selecting, from the discharge port array, an ejection port used for a recording operation on the recording material by the inkjet head.

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