Liquid discharge head device and liquid discharge device

Abstract

To suppress nozzle pitch coming out of an allowable range from being caused at a joint of a nozzle row between liquid discharge heads positioned adjacently to deviate in a head transverse direction.SOLUTION: A liquid discharge head device 6, which comprises a head holding member 61 that holds a plurality of liquid discharge heads 3 and 4 so that the heads are positioned to deviate from each other in a head transverse direction and in a head longitudinal direction, further comprises head fixing members 63a, 63b, 64a and 64b which fix at least respective one end parts in the head longitudinal direction of the plurality of liquid discharge heads to the head holding member and base mounting members 66a and 66b that fixedly mount the head holding member on a base member 63, which is configured so that one end parts 3a and 4a positioned further away from the base mounting members, of end parts in the head longitudinal direction of at least one liquid discharge head can be displaced in the head longitudinal direction relatively with respect to the head holding member that inflates or deflates.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head device and an apparatus for ejecting liquid. [Background technology]

[0002] Conventionally, there is known a liquid ejection head device having a plurality of liquid ejection heads each having a nozzle row in which a plurality of nozzles are arranged in the longitudinal direction of the head, and a head holding member that holds the plurality of liquid ejection heads so that the plurality of liquid ejection heads are positioned offset from one another in the short direction of the head and the longitudinal direction of the head.

[0003] For example, Patent Document 1 discloses an inkjet recording head (liquid ejection head device) having four head bodies (liquid ejection heads) each having two nozzle rows in which a plurality of nozzles are arranged in the head longitudinal direction, and a holding member (head holding member) to which the four head bodies are fixed. In this inkjet recording head, the four head bodies are arranged in a staggered pattern so that they are offset from one another in the head short direction and head longitudinal direction. As a result, the four head bodies form a nozzle region in which nozzles are continuous in the head longitudinal direction at a predetermined nozzle pitch (nozzle pitch within a predetermined tolerance range) with a length approximately four times that of the nozzle row of one head body. Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional liquid ejection head devices have a problem in that a nozzle pitch outside the allowable range may occur at the joint between the nozzle rows of adjacent liquid ejection heads that are misaligned in the short side direction of the head. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a liquid ejection head device having a plurality of liquid ejection heads each having a nozzle row in which a plurality of nozzles are arranged in the longitudinal direction of the head, and a head holding member that holds the plurality of liquid ejection heads so that the plurality of liquid ejection heads are positioned offset from each other in the short direction of the head and the longitudinal direction of the head, the liquid ejection head device having a head fixing member that fixes at least one end of the plurality of liquid ejection heads in the longitudinal direction of the head to the head holding member, and a base mounting member that fixes and mounts the head holding member to a base member, the end of at least one of the plurality of liquid ejection heads in the longitudinal direction of the head that is farther from the base mounting member being configured to be displaceable in the longitudinal direction of the head relative to the expanding or contracting head holding member. Effect of the Invention

[0006] According to the present invention, it is possible to prevent a nozzle pitch that falls outside the allowable range from occurring at a joint between nozzle rows of liquid ejection heads that are adjacent to each other and shifted in the short side direction of the head. [Brief description of the drawings]

[0007] [Figure 1] FIG. 4 is a plan view of the head unit according to the embodiment, as viewed from the normal direction of the recording material. [Diagram 2] FIG. 2 is an explanatory diagram showing the head arrangement of the recording heads provided for each recording section of the head unit. [Diagram 3] 5A and 5B are explanatory diagrams showing the relationship between nozzle pitches of two recording heads on each liquid ejection head device. [Figure 4] FIG. 2 is a block diagram showing the hardware configuration of a control system of an inkjet printing apparatus equipped with the head unit. [Diagram 5] FIG. 2 is a block diagram showing a hardware configuration of a head driving section of the head unit. [Figure 6]13(a) to 13(f) are explanatory diagrams showing examples of test charts in which image recording (dot ejection) was performed by shifting the nozzle switching positions one by one in the overlapping region of two recording heads. [Figure 7] (a) is an explanatory diagram showing the nozzle switching position in the overlapping area of ​​two recording heads, (b) is an explanatory diagram showing the nozzles used for ejection by each of the two recording heads, and (c) is an explanatory diagram showing the shading of a solid image when a solid image is printed with the same amount of droplets from both nozzles. [Figure 8] 1A is a perspective view of one liquid ejection head device as viewed from the nozzle surface (ejection surface) side, and FIG. 1B is a perspective view of one liquid ejection head device as viewed from the opposite side to the nozzle surface. [Figure 9] FIG. 2 is an explanatory diagram showing a nozzle surface of the liquid ejection head device. [Figure 10] 4 is a schematic diagram of a holding plate holding two recording heads in the liquid ejection head device, as viewed from the nozzle surface side. FIG. [Figure 11] 11 is an explanatory diagram showing a comparative example in which a head flange of a recording head is displaced following the displacement of a holding plate when the holding plate expands or contracts. [Figure 12] 11 is an explanatory diagram showing an example of an embodiment in which the head flange of the recording head does not displace in accordance with the displacement of the holding plate even if the holding plate expands or contracts; FIG. [Figure 13] 13 is a cross-sectional view showing a location where a head flange of one recording head and a holding plate are fixed with an elastic adhesive in a modified example. FIG. [Figure 14] 13 is a cross-sectional view showing a location where the head flange of the other recording head and the holding plate are fixed with an elastic adhesive in the modified example. FIG. [Figure 15] FIG. 13 is a plan view illustrating a main portion of another example of a device for discharging liquid. [Figure 16] FIG. [Figure 17] FIG. 13 is a plan view illustrating a main portion of another example of the liquid ejection unit. [Figure 18] FIG. 13 is a front view illustrating still another example of the liquid ejection unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment will be described in which a liquid ejection head device according to the present invention is applied to a head unit of an inkjet recording device, which is an image forming apparatus that ejects liquid.

[0009] First, the head unit in this embodiment will be described. FIG. 1 is a plan view of the head unit 2 as viewed from the normal direction of a recording material P0. The recording material P0 is, for example, paper, and may be roll paper (continuous paper) or cut paper. It may also be various media other than paper (such as cloth). The recording material P0 is transported along the transport direction indicated by the arrow in Fig. 1. The head unit 2 is supported so as to face the recording surface of the recording material P0 at a predetermined distance.

[0010] The head unit 2 is equipped with a K recording section 2K, a C recording section 2C, an M recording section 2M and a Y recording section 2Y as liquid ejection head devices for each color, which are provided corresponding to each of the inks (liquids) of black (K), cyan (C), magenta (M) and yellow (Y).

[0011] The recording units 2K, 2C, 2M, and 2Y of the respective colors are equipped with three liquid ejection head devices 6A, 6B, and 6C each having two recording heads 3 and 4 as liquid ejection heads. The liquid ejection head devices 6A, 6B, and 6C are of the same configuration, and the recording heads 3 and 4 are also of the same configuration. The two recording heads 3 and 4 provided in each liquid ejection head device 6A, 6B, and 6C are arranged so as to be offset from each other in the head short-side direction (the up-down direction in FIG. 1) and the head long-side direction (the left-right direction in FIG. 1), as shown in FIG. 1.

[0012] In this embodiment, the nozzle rows of the two recording heads 3, 4 are arranged so that they partially overlap each other in the head longitudinal direction, but this is not limited to this. For example, the two recording heads 3, 4 may be arranged so that the nozzle rows of the two recording heads 3, 4 do not overlap each other in the head longitudinal direction, and the nozzle pitch between the end nozzles located at one end of each of the nozzle rows of the two recording heads 3, 4 is a predetermined nozzle pitch.

[0013] In the recording units 2K, 2C, 2M, and 2Y of each color, the three liquid ejection head devices 6A, 6B, and 6C are provided so that the two recording heads 3 and 4 that span between two adjacent liquid ejection head devices 6A, 6B, and 6C are positioned offset from each other in the head short-side direction and are arranged so that a portion of each nozzle row overlaps with each other in the head long-side direction (left-right direction in FIG. 1). As a result, in the recording units 2K, 2C, 2M, and 2Y of each color, the recording heads 3 and 4 are arranged in a staggered pattern along the recording material width direction (direction perpendicular to the transport direction), which is the head long-side direction, as shown in FIG.

[0014] By arranging the recording heads 3 and 4 in this manner in the recording sections 2K, 2C, 2M, and 2Y of each color, it is possible to expand the recording range in the head longitudinal direction in the entire recording section (the range in which an image can be recorded by ink ejected from the nozzles 5). As a result, it is possible to obtain a recording section with a recording range that spans the width direction of the recording material P0 and realize a line-type head unit 2, so that an image can be formed on the recording material P0 in one pass without scanning the head unit 2.

[0015] It should be noted that the number of recording units mounted on the head unit 2, the number of recording heads arranged in the recording units, the type of liquid (ink color, etc.) ejected from the recording units, etc. can be set arbitrarily. Therefore, for example, the head unit 2 may be a head unit that includes only a black recording unit 2K and performs recording in black alone.

[0016] FIG. 2 is an explanatory diagram showing the head arrangement of the recording head 3 and the recording head 4 provided for each recording section of the head unit 2. As shown in FIG. The recording head 3 and the recording head 4 each have a nozzle row (for example, a nozzle row consisting of 800 nozzles) in which a plurality of nozzles 5 are arranged in the longitudinal direction of the head. In this embodiment, an example in which there is one nozzle row will be described, but a configuration in which two or more nozzle rows are arranged in the recording material transport direction may also be used. Furthermore, the nozzle row may be arranged so that the nozzle row direction is inclined with respect to the longitudinal direction of the head.

[0017] FIG. 3 is an explanatory diagram showing the relationship between the nozzle pitches of the two recording heads 3 and 4 on each of the liquid ejection head devices 6A, 6B, and 6C. In this embodiment, on one liquid ejection head device 6A, 6B, 6C, one of the two recording heads 3, 4 is arranged so that it partially overlaps with the other recording head 4, and part of each nozzle row overlaps with each other in the head longitudinal direction.

[0018] In the nozzle array provided in the recording heads 3 and 4 of this embodiment, there are a normal region as a first nozzle group in which the nozzles 5 are arranged at a normal pitch P1, and a narrow region as a second nozzle group in which the nozzles 5 are arranged at a pitch P2 narrower than the normal pitch P1. In this embodiment, most of the nozzle array is the normal region, but the narrow region is provided only on one end side of the nozzle array. Note that instead of the narrow region, a wide region in which the nozzles 5 are arranged at a pitch wider than the normal pitch P1 may be used.

[0019] That is, in this embodiment, it is sufficient that the nozzle pitch P2 of the recording head 3 and the nozzle pitch P1 of the recording head 4 are configured to be different in the nozzle row overlapping portion (overlap region) between the recording head 3 and the recording head 4. With this configuration, even if the recording head 3 and the recording head 4 are not positioned with high accuracy, the nozzles that minimize the deviation in the head longitudinal position between the recording head 3 and the recording head 4 in the overlap region are determined. Therefore, if each recording head is operated so that the nozzles used by each recording head 3, 4 are switched with these nozzles, it is possible to suppress uneven recording caused by pitch deviation (nozzle pitch outside the allowable range) at the switching point of the recording width between the recording heads 3, 4.

[0020] Note that the nozzle (nozzle switching position) at which the deviation in the head longitudinal direction position between the recording head 3 and the recording head 4 is minimum may be different from the minimum deviation in the head longitudinal direction position between the recording head 3 and the recording head 4, so long as it is a position at which the distance between dots (dot pitch) is indistinguishable when ink is actually ejected after the head unit 2 is assembled. Note that the determined nozzle switching position is stored in the storage unit 620, which will be described later.

[0021] Note that the above explanation is about the nozzle switching positions in the nozzle row overlapping portion (overlap area) between the two recording heads 3 and 4 on each liquid ejection head device 6A, 6B, 6C, but the same applies to the nozzle switching positions of the two recording heads 3 and 4 spanning between two adjacent liquid ejection head devices 6A, 6B, 6C.

[0022] In this embodiment, both the normal pitch P1 and the narrow pitch P2 are set to be the same pitch between the recording head 3 and the recording head 4. Therefore, the recording head 3 and the recording head 4 can be configured identically. Therefore, the liquid ejection head devices 6A, 6B, and 6C of this embodiment can be manufactured by preparing only one type of recording head, and the manufacturing cost can be kept low compared to when the recording head 3 and the recording head 4 have different configurations.

[0023] FIG. 4 is a block diagram showing the hardware configuration of a control system of the inkjet recording apparatus 1 equipped with the above-mentioned head unit 2. As shown in FIG. In addition to the head unit 2 described above, the inkjet recording apparatus 1 is configured with a control unit 600, a transport drive unit 710, an operation display unit 720, and an input / output interface 730, all of which are interconnected via a bus line 740.

[0024] The head unit 2 is equipped with a head driving section 20 that drives the recording heads 3, 4 arranged in the recording sections 2K, 2C, 2M, 2Y of each color. The head driving section 20 generates a driving waveform that deforms each piezoelectric element, which is an electromechanical conversion element serving as an actuator in each recording head 3, 4 of each recording section 2K, 2C, 2M, 2Y, in response to a control signal input from the control section 600. When this driving waveform is input to each piezoelectric element of each recording head 3, 4 of each recording section 2K, 2C, 2M, 2Y, the liquid in a pressure chamber communicating with the nozzle 5 is pressurized, ejection energy is applied, and ink is ejected from the corresponding nozzle 5.

[0025] The control unit 600 has a CPU (Central Processing Unit) 610, a storage unit 620, a RAM (Random Access Memory) 630, and a ROM (Read Only Memory) 640. The CPU 610 reads out various control programs and setting data stored in the ROM 640, stores them in the RAM 630, executes them, and performs various arithmetic processing. The CPU 610 also controls the overall operation of the inkjet recording apparatus 1.

[0026] The memory unit 620 stores a print job (image recording command) and image data (image information) to be printed that are input via the input / output interface 730, as well as the connecting nozzle positions of recording head 3 and recording head 4 that are generated based on a test chart for detecting the head connecting nozzle positions, which will be described later.

[0027] The conveyance driving section 710 supplies a drive signal to a conveyance motor based on a control signal supplied from the control section 600, and conveys the recording material P0 at a predetermined speed and timing. The operation display unit 720 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as a touch panel arranged over the screen of the display device and operation keys. The operation display unit 720 displays various information on the display device, and also supplies the control unit 600 with an operation signal corresponding to a user's input operation on the input device. The input / output interface 730 mediates the transmission and reception of data between the external device 800 and the control unit 600 . The bus line 740 is a path for transmitting and receiving signals between the control unit 600 and other components.

[0028] FIG. 5 is a block diagram showing the hardware configuration of the head driving section 20 of the head unit 2. As shown in FIG. In FIG. 5, for simplicity of the drawing, only one recording head 3 is shown, and the other recording heads are omitted.

[0029] The head driving unit 20 includes driving waveform correction units 21-1 to 21-N corresponding to the nozzles 5-1 to 5-N (where "N" is the number of nozzles on the recording head 3) on the recording head 3, a head control unit 22, a basic driving waveform generation unit 23, and a driving waveform correction information storage unit 24.

[0030] The head control unit 22 converts the image data input from the control unit 600 into control signals for the recording heads 3 and the nozzles 5-1 to 5-N of the recording heads 4 of the recording units 2K, 2C, 2M, and 2Y. Based on a control signal input from the head control unit 22, the basic drive waveform generation unit 23 generates a basic drive waveform that enables a reference ejection operation according to the image pattern, conveying speed, and printing environment such as temperature and humidity. The drive waveform correction information storage unit 24 stores information indicating the nozzle numbers of nozzles that require correction, and information indicating the amount of correction.

[0031] The drive waveform correction units 21-1 to 21-N correct the basic drive waveform of the drive voltage supplied from the basic drive waveform generation unit 23 based on correction information read from the drive waveform correction information storage unit 24, and supply the corrected basic drive waveform to each piezoelectric element corresponding to the nozzles 5-1 to 5-N, respectively. This makes it possible to give different ejection characteristics to each of the nozzles 5-1 to 5-N, enabling appropriate ink ejection from each of the nozzles 5-1 to 5-N.

[0032] In this embodiment, different ejection characteristics are given to each nozzle, but this is not limited to this. That is, ejection characteristics may be given in units of nozzle rows, or in units of areas with different pitches. The unit in which the ejection characteristics are given may be determined according to constraints such as the memory of the device and the load of the applied voltage.

[0033] FIG. 6 is an explanatory diagram showing an example of a test chart printed on the recording material P0. 6(a) to (f), image recording (dot ejection) was performed by shifting the nozzle switching position one by one in the overlapping region of recording head 3 and recording head 4. Note that the open circles in Fig. 6 indicate dots made of ink ejected from the nozzles of recording head 3, and the filled circles in Fig. 6 indicate dots made of ink ejected from the nozzles of recording head 4.

[0034] In the example of the nozzle switching position shown in Figure 6(a), the distance between the extreme dot in recording head 3 (the right end in Figure 6) and the extreme dot in recording head 4 (the left end in Figure 6) is too close, and the inter-dot distance Xa is significantly different from the inter-dot distance X1 corresponding to the normal region and the inter-dot distance X2 corresponding to the narrow region. In this case, the dot density at this nozzle switching position is locally high, and therefore the image density at the position in the head longitudinal direction corresponding to that nozzle switching position is locally high, causing uneven image density in the head longitudinal direction.

[0035] 6(f), the distance between the extreme dot in recording head 3 (the right end in FIG. 6) and the extreme dot in recording head 4 (the left end in FIG. 6) is so far that the inter-dot distance Xf is significantly different from the inter-dot distance X1 corresponding to the normal region and the inter-dot distance X2 corresponding to the narrow region. In this case, the dot density at this nozzle switching position is locally low, and therefore the image density at the position in the head longitudinal direction corresponding to that nozzle switching position is locally low, again causing image density unevenness in the head longitudinal direction.

[0036] 6(a)-(f), the nozzle switching position shown in Fig. 6(d) can minimize the deviation from the dot-to-dot distance X1 corresponding to the normal region and the dot-to-dot distance X2 corresponding to the narrow region. In this case, the dot density at this nozzle switching position is approximately the same as the dot density at the locations corresponding to the normal region and the narrow region (nozzle pitch within the allowable range), and image density unevenness in the head longitudinal direction is suppressed.

[0037] The nozzle switching position where the deviation is minimized is determined, for example, by visually checking a test chart and determining the position where it is judged that there is the least image density unevenness. Also, for example, the test chart may be photographed with a scanner or a camera, the captured image may be processed for image processing to measure the dot pitch, and the nozzle switching position where the deviation is minimized may be determined. As a condition for determining the nozzle switching position in this case, a condition of selecting the case where the dot pitch X satisfies X2 < X < X1 can be adopted, but it is not limited to this. For example, a condition of selecting the case where the dot pitch X is closest to the dot pitch X1 in the normal region may be adopted.

[0038] FIG. 7 is an explanatory diagram showing an example of printing a solid image on a recording material P0 after determining the switching position of the nozzles. As shown in FIG. 7(a), when the nozzle switching position in the overlapping region of the recording head 3 and the recording head 4 is determined, the nozzles used for ejection by the recording head 3 and the recording head 4 are set as shown in FIG. 7(b). In this case, in the vicinity of the nozzle switching position (the joint of the heads), as shown in FIG. 7(c), in order from the left, an image portion printed in the normal region (nozzle pitch P1) of the recording head 3, an image portion printed in the narrow region (nozzle pitch P2) of the recording head 3, and an image portion printed in the normal region (nozzle pitch P1) of the recording head 4 are arranged.

[0039] At this time, when a solid image is printed with the same amount of droplet volume (liquid ejection volume) from any of the nozzles 5, the dot pitch X2 of the image portion printed in the narrow region is narrower than the dot pitch X1 of the image portion printed in the normal region, the ink coverage rate with respect to the recording material P0 increases, and the image density becomes higher than that in the normal region.

[0040] That is, when a solid image is printed with the same amount of droplet volume (liquid ejection volume) from any of the nozzles 5, even if the narrow region and the normal region with different nozzle pitches are provided to optimize the nozzle switching position and local image density unevenness at the nozzle switching position can be suppressed, a new image density unevenness occurs in which a shading occurs between the narrow region and the normal region.

[0041] Therefore, in this embodiment, the droplet volume (liquid ejection volume) is made different between the nozzles in the narrow area and the nozzles in the normal area, thereby reducing the image density difference between the narrow area and the normal area and suppressing the new image density unevenness described above.

[0042] Here, the following formula (1) generally holds between the droplet volume Mj and the droplet velocity Vj.

[0043]

number

[0044] In the above formula (1), "A" is the nozzle opening area as the nozzle size, "Tc" is the natural vibration period which is the natural vibration characteristic of the pressure chamber communicating with each nozzle, and "k" is a coefficient. From this formula (1), it can be seen that when trying to change the droplet volume Mj while maintaining the droplet velocity Vj, it is sufficient to change the product of the nozzle opening area A and the natural vibration period Tc at the same ratio as the droplet volume Mj.

[0045] In this embodiment, three liquid ejection head devices 6A, 6B, and 6C are arranged in the head longitudinal direction to form recording sections 2K, 2C, 2M, and 2Y with a recording range across the width direction of the recording material P0, to realize a line-type head unit 2, but the present invention is not limited to this. For example, the head unit may be formed of a single liquid ejection head device 6. This head unit can realize a scanning-type head unit by being mounted on a carriage that reciprocates in the width direction (main scanning direction) of the recording material P0, for example.

[0046] Next, the liquid ejection head devices 6A, 6B, and 6C in this embodiment will be described in more detail. Figure 8(a) is an oblique view of one liquid ejection head device 6 when viewed from the nozzle surface (ejection surface) side, and Figure 8(b) is an oblique view of one liquid ejection head device 6 when viewed from the side opposite the nozzle surface. FIG. 9 is an explanatory diagram showing the nozzle surface of the liquid ejection head device 6. As shown in FIG.

[0047] The liquid ejection head device 6 of this embodiment includes, in addition to the two recording heads 3 and 4, a holding plate 61 serving as a head holding member for holding the recording heads 3 and 4, a nozzle cover 62, a base member 63, a device main body 64, and the like.

[0048] The nozzle cover 62 is a cover member that is attached so as to cover the holding plate 61 described later. As shown in Fig. 8, the nozzle cover 62 is provided with two openings 62a and 62b for exposing the nozzle surfaces of the two recording heads 3 and 4 held by the holding plate 61, respectively. The base member 63 is a member that serves as the base of the structure of the liquid ejection head device 6, and components of the recording heads 3 and 4 (flow path members, piezoelectric elements, etc.) are disposed inside the base member 63. The head drive unit 20 is disposed inside the device main body 64, and is provided with a connector 69a for connecting a transmission line between the head drive unit 20 and the control unit 600, an ink port 69b for supplying ink, and the like.

[0049] FIG. 10 is a schematic diagram of a holding plate 61 holding two recording heads 3 and 4, as viewed from the nozzle surface side. The holding plate 61 is a plate-like member that holds the two recording heads 3, 4 so that the two recording heads 3, 4 are positioned offset from each other in the short direction of the heads (up and down direction in Figure 10) and so that portions of each nozzle row of the two recording heads 3, 4 overlap with each other in the long direction of the heads (left and right direction in Figure 10).

[0050] The two recording heads 3 and 4 are fitted into respective fitting holes formed in a holding plate 61. Head flanges 3a, 3b, 4a, and 4b are provided at each end in the head longitudinal direction of each of the recording heads 3 and 4. The two recording heads 3 and 4 are fixed to the holding plate 61 by fastening the head flanges 3a, 3b, 4a, and 4b to the holding plate 61 with head fixing screws 63a, 63b, 64a, and 64b, which are screw fastening members serving as head fixing members.

[0051] The plate shape of the holding plate 61 may be a typical rectangular shape, but in this embodiment, as shown in Fig. 10, it has a stepped shape that fits along the outer periphery of the two recording heads 3, 4 arranged in a stepped manner. That is, in the holding plate 61 of this embodiment, notches 65, 65 shown by dashed lines in the figure are formed in each region that faces, from the head longitudinal direction, the head longitudinal direction end on the side where the overlapping nozzle row portions (nozzle row overlapping portions) of the recording heads 3, 4 are located.

[0052] Furthermore, by forming the holding plate 61 in such a stepped shape, the amount of material used in the liquid ejection head device 6 can be reduced, thereby reducing the cost and weight. Furthermore, because the holding plate 61 has such a stepped shape, when arranging the two recording heads 3, 4 that span the two adjacent liquid ejection head devices 6A, 6B, 6C so that a portion of each nozzle row overlaps with each other, as described above, it is not necessary to arrange the two adjacent liquid ejection head devices 6A, 6B, 6C so as to be shifted from each other in the head short side direction as shown in Fig. 1. Therefore, it is possible to reduce the dimensions of the recording units 2K, 2C, 2M, 2Y of each color in the head short side direction (recording material conveying direction).

[0053] For the purpose of reducing costs, the holding plate 61 of this embodiment is made of an inexpensive material (a material that expands and contracts more easily than the base member and the recording heads 3 and 4) that expands and contracts easily due to temperature changes in the head transportation environment, usage environment, etc. Specifically, the inexpensive holding plate 61 may be made of stainless steel (SUS430, etc.) that has a large linear expansion coefficient.

[0054] However, in such a holding plate 61, when the holding plate 61 expands or contracts due to a temperature change or the like, each end portion 61c, 61d of the holding plate 61 facing the notches 65, 65 of the holding plate 61 is displaced as shown by the white arrow R in FIG. 11. Then, due to the displacement caused by this expansion or contraction, the ends (head flanges 3b, 4a) of the recording heads 3, 4 fixed to the holding plate 61 by the head fixing screws 63a, 63b, 64a, 64b are displaced. As a result, the recording heads 3, 4 are pulled or compressed in the head longitudinal direction, and the nozzle positions in the nozzle row overlapping portion (overlap region) of each recording head 3, 4 are displaced. As a result, a relative positional deviation of the nozzles occurs between the two recording heads 3, 4, and a nozzle pitch that falls outside the allowable range is generated in the nozzle row overlapping portion (the joint portion between the recording heads 3, 4).

[0055] More specifically, the holding plate 61 of this embodiment is provided with mount flanges 61a, 61b at each end in the head longitudinal direction. The holding plate 61 is fixed to the base member 63 by fastening the mount flanges 61a, 61b to the base member 63 with mount screws 66a, 66b, which are screw fastening members serving as base attachment members. The mount flanges 61a, 61b (fixed portions) of the holding plate 61 fixed to the base member 63 with the mount screws 66a, 66b or their vicinity are restrained by the base member 63, so that even if the holding plate 61 tries to expand or contract, displacement is suppressed.

[0056] In contrast, end edge portions 61c, 61d of the holding plate 61 located on the opposite side of the head longitudinal direction from the mount flanges 61a, 61b or their vicinity are not fixed to the base member 63 and are far from the points (mount flanges 61a, 61b) fixed by the mount screws 66a, 66b, and therefore are not restrained by the base member 63. Therefore, when the holding plate 61 expands or contracts due to a temperature change or the like, the end edge portions 61c, 61d of the holding plate 61 are displaced in the head longitudinal direction as shown by the outlined arrow R in FIG.

[0057] Therefore, when the holding plate 61 expands or contracts, among the head flanges 3a, 3b, 4a, and 4b of the two recording heads 3 and 4 held by the holding plate 61, the head flanges 3a and 4b located near the mount flanges 61a and 61b of the holding plate 61 are restrained from displacing, while the head flanges 3b and 4a located near the end portions 61c and 61d of the holding plate 61 (parts far from the head flanges 3a and 4b) are displaced in the head longitudinal direction as shown by the black arrows S in Fig. 11. The end portions of the recording heads 3 and 4 on the head flange 3b and 4a side that displace in this manner are on the side where the nozzle row overlapping portions of the recording heads 3 and 4 are located, so that a relative positional deviation of the nozzles in the nozzle row overlapping portions between the two recording heads 3 and 4 occurs, resulting in a nozzle pitch that falls outside the allowable range.

[0058] Therefore, in this embodiment, of the head fixing screws 63a, 63b that fix the head flanges 3a, 3b of the recording head 3, the head fixing screw 63b, which is the first head fixing member that is farther away from the mount screw 66a, is configured as a displaceable fixing member. More specifically, the head fixing screw 63b is configured so that the head flange 3b of the recording head 3 can be displaced in the head longitudinal direction relative to the expanding or contracting holding plate 61. The head fixing screw 63b as such a displaceable fixing member is realized, for example, by adjusting the tightening torque to be weaker than that of the head fixing screw 63a, which is the second head fixing member that is closer to the mount screw 66a.

[0059] Specifically, as the holding plate 61 expands or contracts, the displacement force (relative displacement force in the head longitudinal direction) generated between the holding plate 61 and the head flanges 3a, 3b of the recording head 3 gradually increases. Then, when the displacement force exceeds the fastening force therebetween (such as the maximum static friction force between the holding plate 61 and the recording head 3), the head flanges 3a, 3b of the recording head 3 become displaceable relative to the holding plate 61 in the head longitudinal direction.

[0060] At this time, if the tightening torque of the head fixing screw 63b is adjusted to be weaker than that of the head fixing screw 63a, the fastening force between the holding plate 61 fastened by the head fixing screw 63b and the head flange 3b of the recording head 3 becomes weaker than the fastening force between the holding plate 61 fastened by the head fixing screw 63a and the head flange 3a of the recording head 3. As a result, even if the holding plate 61 expands or contracts, the head flange 3a of the recording head 3 (the one closer to the mount screw 66a) remains constrained by the base member 63 and does not displace, while the head flange 3b of the recording head 3 (the one farther from the mount screw 66a) becomes displaceable relative to the holding plate 61 in the head longitudinal direction and does not displace.

[0061] 12, even if the holding plate 61 is displaced as indicated by the white arrow R due to expansion or contraction of the holding plate 61, the recording head 3 is not pulled or compressed in the head longitudinal direction, and the position of the recording head 3 is maintained fixed at a predetermined position relative to the base member 63. Therefore, even if the holding plate 61 expands or contracts due to temperature changes or the like, the nozzle positions in the nozzle row overlapping portion of the recording head 3 are prevented from being displaced.

[0062] The above description of the recording head 3 also applies to the recording head 4. Therefore, even when the holding plate 61 expands or contracts, the recording head 4 is not pulled or compressed in the head longitudinal direction, and the position of the recording head 4 is maintained fixed at a predetermined position relative to the base member 63. Therefore, even if the holding plate 61 expands or contracts due to temperature changes or the like, the nozzle positions in the nozzle row overlapping portion of the recording head 4 are prevented from being displaced.

[0063] As a result of the above, it is possible to prevent the occurrence of a nozzle pitch outside the permissible range in the overlapping portion of the nozzle rows of the two print heads 3 and 4.

[0064] [Modifications] Next, a modified example of the head fixing member for fixing the head flanges 3a, 3b, 4a, and 4b of the recording heads 3 and 4 to the holding plate 61 in this embodiment will be described. In the above-described embodiment, the head fixing screws 63a, 63b, 64a, and 64b, which are screw fastening members, are used as the head fixing members, but in this modified example, an elastically deformable adhesive is used as the head fixing member.

[0065] FIG. 13 is a cross-sectional view showing the locations where the head flanges 3a and 3b of the recording head 3 and the holding plate 61 are fixed with elastic adhesives 67a and 67b. In this modification, of the elastic adhesives 67a, 67b that fix the head flanges 3a, 3b of the recording head 3, the elastic adhesive 67b, which is the first head fixing member farther from the mount screw 66a, is configured as a displaceable fixing member. More specifically, the elastic adhesive 67b is configured to be elastically deformable so that the head flange 3b of the recording head 3 can be displaced in the head longitudinal direction relative to the expanding or contracting holding plate 61. An example of the elastic adhesive 67b as a displaceable fixing member is a silicone adhesive.

[0066] Here, in this modified example, both head flanges 3a, 3b of the recording head 3 are fixed with elastic adhesives 67a, 67b, but the amount of elastic adhesive 67b applied to the first head fixing member located farther from the mount screw 66a is adjusted to be less than the amount of elastic adhesive 67a applied to the second head fixing member located closer to the mount screw 66a.

[0067] When the amount of application of the elastic adhesive 67b is adjusted to be less than the amount of application of the elastic adhesive 67a, the area between the holding plate 61 and the head flange 3b of the recording head 3, which are bonded by the elastic adhesive 67b, is more likely to elastically deform than the area between the holding plate 61 and the head flange 3a of the recording head 3, which are bonded by the elastic adhesive 67a. Therefore, when the holding plate 61 expands or contracts, the elastic adhesive 67a does not elastically deform in the head flange 3a of the recording head 3 (the one closer to the mount screw 66a) and the head flange 3a remains restrained by the base member 63 and does not displace. On the other hand, the elastic adhesive 67b of the head flange 3b of the recording head 3 (the one farther from the mount screw 66a) is elastically deformed, which makes it possible to displace the head flange 3b relatively to the holding plate 61 in the head longitudinal direction, and therefore the head flange 3b does not displace.

[0068] Therefore, even in this modified example, even if the holding plate 61 is displaced due to expansion or contraction of the holding plate 61, the recording head 3 is not pulled or compressed in the head longitudinal direction, and the position of the recording head 3 is maintained fixed at a predetermined position relative to the base member 63. Therefore, even if the holding plate 61 expands or contracts due to temperature changes or the like, the nozzle positions in the nozzle row overlapping portion of the recording head 3 are prevented from being displaced.

[0069] FIG. 14 is a cross-sectional view showing the locations where the head flanges 4a and 4b of the recording head 4 and the holding plate 61 are fixed with elastic adhesives 68a and 68b. The recording head 4 is similar to the recording head 3 described above, and the application amount of the elastic adhesive 68a, which is the first head fixing member farther from the mount screw 66b, is adjusted to be less than the application amount of the elastic adhesive 68b, which is the second head fixing member closer to the mount screw 66b. Therefore, similar to the recording head 3 described above, even when the holding plate 61 expands or contracts, the recording head 4 is not pulled or compressed in the head longitudinal direction, and the position of the recording head 4 is maintained fixed at a predetermined position relative to the base member 63. Therefore, even if the holding plate 61 expands or contracts due to a temperature change or the like, the nozzle positions in the nozzle row overlapping portion of the recording head 4 are suppressed from being displaced.

[0070] As a result of the above, in this modified example as well, it is possible to prevent the occurrence of a nozzle pitch outside the permissible range in the overlapping portion of the nozzle rows of the two print heads 3 and 4.

[0071] In this embodiment (including the above-mentioned modified example), the head fixing member (head fixing screws 63b, 64a, elastic adhesives 67b, 68a) farthest from the mounting screws 66a, 66b is configured as a displaceable fixing member for both of the two recording heads 3, 4 provided in the liquid ejection head device 6, but it may be applied to only one of the recording heads 3, 4. In this case, although the effect of suppressing the occurrence of a nozzle pitch that falls outside the allowable range decreases, it is possible to suppress the occurrence of a nozzle pitch that falls outside the allowable range in the nozzle row overlap portion of the two recording heads 3, 4.

[0072] Next, another example of the liquid ejecting device according to the present invention will be described with reference to FIGS. FIG. 15 is an explanatory plan view of the main part of the device, and FIG. 16 is an explanatory side view of the main part of the device. This device is a serial type device, and a carriage 403 is reciprocated in the main scanning direction by a main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is hung between left and right side plates 491A and 491B to movably hold the carriage 403. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via a timing belt 408 hung between a drive pulley 406 and a driven pulley 407.

[0073] A liquid ejection unit 440 is mounted on the carriage 403, which is an integral combination of a liquid ejection head device 404 according to the present invention and a head tank 441. The liquid ejection head device 404 of the liquid ejection unit 440 is provided with a recording unit that ejects liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K), similar to the head unit 2 of the above-described embodiment. Also, the recording unit for each color in the liquid ejection head device 404 is provided with recording heads 3 and 4 each having a nozzle row made up of a plurality of nozzles, which are arranged in a staggered pattern, similar to the recording units 2K, 2C, 2M, and 2Y of the above-described embodiment, and the nozzle row direction is aligned along the sub-scanning direction (head longitudinal direction) perpendicular to the main scanning direction, and the ejection direction is directed downward.

[0074] The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by a supply mechanism 494 for supplying the liquid stored outside the liquid ejection head device 404 to the liquid ejection head device 404 .

[0075] The supply mechanism 494 is composed of a cartridge holder 451 which is a filling section to which a liquid cartridge 450 is attached, a tube 456, a liquid delivery unit 452 including a liquid delivery pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. The liquid is delivered from the liquid cartridge 450 to the head tank 441 by the liquid delivery unit 452 via the tube 456.

[0076] This device is equipped with a transport mechanism 495 for transporting paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

[0077] The conveyor belt 412 attracts the paper 410 and conveys it to a position facing the liquid ejection head device 404. The conveyor belt 412 is an endless belt, and is stretched between a conveyor roller 413 and a tension roller 414. The paper can be attracted by electrostatic attraction or air suction.

[0078] The conveyor belt 412 moves in a circular motion in the sub-scanning direction as the conveyor rollers 413 are rotated by a sub-scanning motor 416 via a timing belt 417 and a timing pulley 418 .

[0079] Furthermore, a maintenance and recovery mechanism 420 for performing maintenance and recovery of the liquid ejection head device 404 is disposed on one side of the conveyor belt 412 on one side of the carriage 403 in the main scanning direction.

[0080] The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (surface on which nozzles are formed) of the liquid ejection head device 404, a wiper member 422 that wipes the nozzle surface, and the like.

[0081] The main scanning movement mechanism 493, the supply mechanism 494, the maintenance and recovery mechanism 420, and the transport mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

[0082] In the device thus configured, a sheet of paper 410 is fed onto and adsorbed to the conveyor belt 412, and the sheet of paper 410 is conveyed in the sub-scanning direction by the circular movement of the conveyor belt 412.

[0083] Thus, by driving a liquid ejection head device 404 in response to an image signal while moving a carriage 403 in the main scanning direction, liquid is ejected onto a stationary paper 410 to form an image.

[0084] In this manner, since this device is equipped with the liquid ejection head according to the present invention, it is possible to stably form high quality images.

[0085] Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 17 is an explanatory plan view of the main part of the unit.

[0086] This liquid ejection unit is composed of a housing portion consisting of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid ejection head device 404, among the components that make up the device that ejects the liquid.

[0087] It should be noted that a liquid discharge unit can also be configured in which at least one of the above-mentioned maintenance and recovery mechanism 420 and supply mechanism 494 is further attached to, for example, side plate 491B of this liquid discharge unit.

[0088] Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 18 is a front view of the unit.

[0089] This liquid discharge unit is composed of a liquid discharge head device 404 to which a flow path part 444 is attached, and a tube 456 connected to the flow path part 444 .

[0090] The flow path part 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path part 444. A connector 443 for electrically connecting with the liquid ejection head device 404 is provided on the upper part of the flow path part 444.

[0091] In this application, a "liquid ejection device" is a device that includes a liquid ejection head, a liquid ejection head device, or a liquid ejection unit, and ejects liquid by driving the liquid ejection head. A liquid ejection device includes not only a device that can eject liquid onto an object onto which the liquid can adhere, but also a device that ejects liquid into air or liquid.

[0092] This "liquid ejecting device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0093] For example, examples of "devices that eject liquid" include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0094] In addition, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves and devices that create three-dimensional images.

[0095] The above-mentioned "material to which liquid can adhere" means material to which liquid can adhere at least temporarily, material to which liquid adheres and sticks, material to which liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording materials, electronic substrates, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, all materials to which liquid can adhere are included.

[0096] The material of the "material to which a liquid can adhere" may be any material to which a liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, building materials such as wallpaper and flooring, and textiles for clothing.

[0097] The term "liquid" also includes ink, processing liquid, DNA sample, resist, pattern material, binder, modeling liquid, or solutions and dispersions containing amino acids, proteins, or calcium.

[0098] Furthermore, the "liquid ejection device" may be a device in which a liquid ejection head and an object to which liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which a liquid ejection head moves, a line type device in which a liquid ejection head does not move, etc.

[0099] Other examples of "liquid ejecting devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0100] A "liquid ejection unit" is a collection of components related to ejecting liquid, in which functional parts and mechanisms are integrated with a liquid ejection head. For example, a "liquid ejection unit" includes a combination of a liquid ejection head and at least one of the following components: a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism.

[0101] Here, integration includes, for example, a liquid ejection head, a functional part, and a mechanism that are fixed to each other by fastening, bonding, engaging, etc., and one is held movably relative to the other. Also, the liquid ejection head, the functional part, and the mechanism may be configured to be detachable from each other.

[0102] For example, there are liquid ejection units in which the liquid ejection head and the head tank are integrated, such as liquid ejection unit 440 shown in Fig. 16. There are also liquid ejection units in which the liquid ejection head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

[0103] Furthermore, there is a liquid ejection unit in which the liquid ejection head and the carriage are integrated.

[0104] In some liquid ejection units, the liquid ejection head is movably held by a guide member that constitutes a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated together. In other liquid ejection units, as shown in Fig. 17, the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated together.

[0105] Furthermore, there is a liquid ejection unit in which a cap member, which is part of the maintenance and recovery mechanism, is fixed to a carriage on which the liquid ejection head is attached, thereby integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

[0106] As another liquid ejection unit, as shown in FIG. 18, there is a liquid ejection head having a head tank or a flow path part attached thereto and a tube is connected to the liquid ejection head, so that the liquid ejection head and a supply mechanism are integrated.

[0107] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0108] Furthermore, the actuator used in the "liquid ejection head" is not limited. For example, in addition to the piezoelectric element (which may use a laminated piezoelectric element) described in the above embodiment, a thermal actuator using an electrothermal conversion element such as a heating resistor, or an electrostatic actuator consisting of a vibration plate and an opposing electrode may be used.

[0109] In addition, in the present application, the terms image formation, recording, printing, imprinting, printing, modeling, and the like are all synonymous.

[0110] Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. Each of the novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Such embodiments and modifications of the embodiments are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0111] The above description is merely an example, and each of the following aspects provides unique effects. [First aspect] The first aspect is a liquid ejection head device 6 having a plurality of liquid ejection heads (e.g., recording heads 3 and 4) each having a nozzle row in which a plurality of nozzles 5 are arranged in the head longitudinal direction, and a head holding member (e.g., a holding plate 61) that holds the plurality of liquid ejection heads so that the plurality of liquid ejection heads are positioned offset from one another in the head short-side direction and the head longitudinal direction, and a head fixing member (e.g., head fixing screws 6) that fixes at least one end (e.g., head flanges 3a, 3b, 4a, 4b) of each of the plurality of liquid ejection heads in the head longitudinal direction to the head holding member. 3a, 63b, 64a, 64b, elastic adhesive 67a, 67b, 68a, 68b), and a base mounting member (e.g., mounting screws 66a, 66b) for fixing and mounting the head holding member to the base member 63, and among the head longitudinal ends of at least one liquid ejection head (e.g., recording head 3, 4), one end (e.g., head flange 3b, 4a) that is farther from the base mounting member is configured to be displaceable in the head longitudinal direction relative to the head holding member which expands or contracts. In conventional liquid ejection head devices, when the head holding member that holds multiple liquid ejection heads expands or contracts due to temperature changes, etc., this can result in a nozzle pitch that is outside the acceptable range at the joint of the nozzle rows between two adjacent liquid ejection heads that are misaligned in the short direction of the head. More specifically, in this type of liquid ejection head device, each end of each liquid ejection head in the head longitudinal direction (hereinafter simply referred to as "end") is fixed to a head holding member by a head fixing member, and the nozzle pitch at the joints of the nozzle rows is adjusted so as to be within an allowable range. Then, the head holding member to which the multiple liquid ejection heads are fixed in this manner is attached and fixed to a base member by a base mounting member. Here, for the purpose of reducing costs, etc., an inexpensive head holding member that easily expands and contracts due to temperature changes, etc. (a head holding member that expands and contracts more easily than the base member or the liquid ejection head) may be used. In this case, both ends of the liquid ejection head fixed by the head fixing member are displaced relative to the head holding member in response to the displacement of the expanding or contracting head holding member, and the liquid ejection head is pulled or compressed in the head longitudinal direction. As a result, the nozzle positions within the nozzle row joints of each liquid ejection head are displaced, causing a relative positional deviation of the nozzles between two adjacent liquid ejection heads in the short side direction of the head, resulting in a nozzle pitch that is outside the allowable range at the nozzle row joints (joints between liquid ejection heads). In this aspect, of the ends in the head longitudinal direction of at least one of the multiple liquid ejection heads, the end farthest from the base mounting member is configured to be displaceable in the head longitudinal direction relative to the expanding or contracting head holding member, so that even if the head holding member expands or contracts, the end of the liquid ejection head is prevented from being displaced in accordance with the displacement of the head holding member. On the other hand, the other end of the liquid ejection head is fixed to the head holding member by the head fixing member that is closer to the base mounting member. Since the fixed portion of the head holding member that is fixed to the base member by the base mounting member or its vicinity is restrained by the base member, even if the head holding member tries to expand or contract, displacement is suppressed and the head holding member remains fixed to the base member. As a result of the above, when the head holding member expands or contracts, the other end side of the liquid ejection head is restrained by the base member and displacement is suppressed, while the one end side does not follow the displacement of the head holding member. Therefore, even when the head holding member expands or contracts, the liquid ejection head is not pulled or compressed in the head longitudinal direction, and is maintained fixed at a predetermined position on the base member. Therefore, displacement of the nozzle positions within the nozzle row joint portion of the liquid ejection head is suppressed, and it is possible to suppress the occurrence of a nozzle pitch outside the allowable range at the nozzle row joint portion.

[0112] [Second aspect] The second aspect is characterized in that, in the first aspect, the head holding member has notches 65, 65 formed in an area facing the head longitudinal direction of one end portion (e.g., head flanges 3b, 4a) of the at least one liquid ejection head. This allows the cost and weight of the liquid ejection head device 6 to be reduced by reducing the amount of material in the head holding member by the amount of the cutout formed. However, in a configuration with such a cutout, when the head holding member expands or contracts due to temperature changes or the like, each end portion of the head holding member facing the cutout (the portion farthest from the base mounting member) will be displaced. According to this embodiment, one longitudinal end portion of the liquid ejection head arranged near each end portion of the head holding member that displaces in this way is fixed to the head holding member so as to be displaceable relative to the head longitudinal direction, and it is possible to prevent the occurrence of a nozzle pitch that falls outside the allowable range at the joint portion of the nozzle rows.

[0113] [Third aspect] A third aspect is characterized in that, in the first or second aspect, the head holding member holds the multiple liquid ejection heads so that portions of the nozzle rows of each of the multiple liquid ejection heads overlap with each other in the longitudinal direction of the heads. This facilitates the operation of aligning nozzles at joints between nozzle rows of a plurality of liquid ejection heads.

[0114] [Fourth aspect] The fourth aspect is characterized in that, in any one of the first to third aspects, a head fixing member (e.g., head fixing screws 63a, 64b) that fixes the other end portion (e.g., head flanges 3a, 4b) of the at least one liquid ejection head in the head longitudinal direction is arranged in the vicinity of the base mounting member. According to this, the other end of the at least one liquid ejection head in the head longitudinal direction is restrained by the base member, and even if the head holding member tries to expand or contract, the displacement is suppressed. As a result, even if the head holding member expands or contracts, the position of the at least one liquid ejection head remains fixed without changing with respect to the base member, so that it is possible to further suppress the occurrence of a nozzle pitch that falls outside the allowable range at the joint portion of the nozzle rows.

[0115] [Fifth aspect] A fifth aspect is characterized in that, in any of the first to fourth aspects, the at least one liquid ejection head is two adjacent liquid ejection heads shifted in the short side direction of the head, and the one end portions of the two liquid ejection heads are respectively end portions of the two liquid ejection heads that are close to each other. According to this aspect, displacement of the nozzle positions within the joint between the nozzle rows of two adjacent liquid ejection heads that are shifted in the short side direction of the head is suppressed, thereby further suppressing the occurrence of a nozzle pitch that falls outside the acceptable range at the joint between the nozzle rows.

[0116] [Sixth aspect] A sixth aspect is characterized in that, in any of the first to fifth aspects, each end of the plurality of liquid ejection heads in the head longitudinal direction is fixed to the head holding member by the head fixing member, and the head fixing member fixing one end of the at least one liquid ejection head in the head longitudinal direction is a displaceable fixing member that fixes the one end so that it can be displaced relatively in the head longitudinal direction with respect to the head holding member which expands or contracts. This prevents the position of one end of the liquid ejection head from moving significantly (for example, from moving significantly in the short side direction of the head).

[0117] [Seventh aspect] A seventh aspect is characterized in that, in any of the sixth aspects, the head fixing member is a screw fastening member, and the displaceable fixing member is adjusted to a tightening torque weaker than that of a head fixing member that fixes the other end of the at least one liquid ejection head in the head longitudinal direction. According to this, the liquid ejection head can be fixed to the head holding member using a simple structure such as a screw fastening member.

[0118] [Eighth aspect] An eighth aspect is any one of the sixth aspects, characterized in that the displaceable fixing member is an elastically deformable adhesive. According to this, the liquid ejection head can be fixed to the head holding member using a simple structure such as an adhesive.

[0119] [Ninth aspect] A ninth aspect is characterized in that, in the eighth aspect, the head fixing members are made of the same elastically deformable adhesive, and the displaceable fixing member is adjusted to have a smaller amount of adhesive than the head fixing member that fixes the other end of the at least one liquid ejection head in the head longitudinal direction. According to this, the adhesive can be appropriately used as the displaceable fixing member.

[0120] [Tenth aspect] A tenth aspect is a device for ejecting liquid, characterized in that it comprises the liquid ejection head device according to any one of the first to ninth aspects. According to this aspect, even if the head holding member expands or contracts due to temperature changes, etc., the nozzle pitch in overlapping nozzle row portions can be maintained within an acceptable range, thereby providing a device that ejects liquid with improved liquid ejection quality. [Explanation of symbols]

[0121] 1: Inkjet recording device 2: Head unit 2K, 2C, 2M, 2Y: Recording section 3,4: Recording head 3a, 3b, 4a, 4b: Head flange 5: Nozzle 6: Liquid ejection head device 61: Retaining plate 61a, 61b: Mount flange 61c, 61d: Edge part 62: Nozzle cover 63: Base material 63a, 63b, 64a, 64b: Head fixing screws 64: Device main body 65: Notch 66a, 66b: Mounting screws 67a, 67b, 68a, 68b: Elastic adhesive 403: Carriage 404: Liquid ejection head device 405: Main scanning motor 406: Drive pulley 407: Driven pulley 408: Timing belt 410: Paper 412:Conveyor belt 413: Transport roller 414: Tension roller 416: Sub-scanning motor 417: Timing belt 418: Timing pulley 420: Maintenance and recovery mechanism 421: Cap member 422: Wiper member 440: Liquid discharge unit 441: Head Tank 442: Cover 443: Connector 444: Flow path parts 450: Liquid cartridge 451: Cartridge holder 452: Liquid delivery unit 456: Tube 491A: Side plate 491B: Side plate 491C: Back plate 493: Main scanning movement mechanism 494: Supply mechanism 495:Transport mechanism 600: Control section 610: CPU 620: Storage section 630:RAM 640: ROM 710: Transport drive unit 720: Operation display section 730: Input / Output Interface 740: Bus Line 800: External device [Prior art documents] [Patent documents]

[0122] [Patent Document 1] JP 2013-159088 A

Claims

1. A plurality of liquid ejection heads each having a nozzle row in which a plurality of nozzles are arranged in a longitudinal direction of the head; a head holding member that holds the plurality of liquid ejection heads so that the plurality of liquid ejection heads are positioned offset from one another in a head short-side direction and a head long-side direction, a head fixing member that fixes at least one end of each of the plurality of liquid ejection heads in a head longitudinal direction to the head holding member; a base mounting member for fixing and mounting the head holding member to a base member, A liquid ejection head device characterized in that, among the respective longitudinal ends of at least one of the plurality of liquid ejection heads, the end farthest from the base mounting member is configured to be displaceable relative to the head longitudinal direction with respect to the expanding or contracting head holding member.

2. 2. The liquid ejection head device according to claim 1, a head holding member having a notch formed in a region facing, in a longitudinal direction of the head, the one end of the at least one liquid ejection head;

3. 3. The liquid ejection head device according to claim 1, a head holding member that holds the plurality of liquid ejection heads such that nozzle rows of the plurality of liquid ejection heads partially overlap each other in a longitudinal direction of the heads;

4. 3. The liquid ejection head device according to claim 1, a head fixing member for fixing the other end of the at least one liquid ejection head in the head longitudinal direction, the head fixing member being disposed in the vicinity of the base mounting member;

5. 3. The liquid ejection head device according to claim 1, the at least one liquid ejection head is two liquid ejection heads adjacent to each other and shifted in a short side direction of the head, a liquid ejection head device, the liquid ejection heads each having one end portion that is adjacent to the other end of the liquid ejection head;

6. 3. The liquid ejection head device according to claim 1, each end portion of the liquid ejection head in a head longitudinal direction is fixed to the head holding member by the head fixing member; A liquid ejection head device characterized in that the head fixing member that fixes the one end of the at least one liquid ejection head in the head longitudinal direction is a displaceable fixing member that fixes the one end so that it can be displaced relatively in the head longitudinal direction to the head holding member that expands or contracts.

7. 7. The liquid ejection head device according to claim 6, the head fixing member is a screw fastening member, The liquid ejection head device is characterized in that the displaceable fixing member is adjusted to have a tightening torque weaker than that of a head fixing member that fixes the other end portion of the at least one liquid ejection head in the head longitudinal direction.

8. 7. The liquid ejection head device according to claim 6, The liquid ejection head device is characterized in that the displaceable fixing member is an elastically deformable adhesive.

9. 9. The liquid ejection head device according to claim 8, The head fixing members are made of the same elastically deformable adhesive, The liquid ejection head device according to claim 1, wherein the amount of adhesive applied to the displaceable fixing member is adjusted to be less than that applied to a head fixing member that fixes the other end of the at least one liquid ejection head in the head longitudinal direction.

10. 3. A liquid ejection device comprising the liquid ejection head device according to claim 1.

Images