JP2008265191A - Liquid droplet ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet ejection device which maintains each recording head in a positioned and secured state even if an environmental temperature changes. <P>SOLUTION: According to the structure of the liquid droplet ejection device, by expanding/contracting a low rigidity portion 132 of a spacer member 42, a thermal expansion (contraction) difference between the spacer member 42 and the recording head unit 32 is absorbed, and therefore, residual distortion at an adhesive U caused by the thermal expansion (contraction) is reduced. Disengagement of the adhesive U is thereby prevented, and each recording head unit 32 is positioned and secured with high accuracy. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge device that discharges droplets from a nozzle and records an image on a recording medium.

  In a scanning type (so-called PWA type) droplet discharge recording apparatus in which the recording head is moved in a direction crossing the recording medium conveyance direction and sequentially printed, if the number of nozzles is increased for high-speed printing, the mass of the recording head also increases. The increase in the load on the scanning mechanism of the recording head increases the number of nozzles. In addition, an extra scanning distance (idle run) occurs when reversing the reciprocating scanning of the recording head, which is disadvantageous for speeding up.

  As a method for solving these problems, there is a scanning method (so-called FWA method) in which one or more lines are simultaneously printed by a recording head having a width larger than the recording area without moving the recording head in a direction crossing the conveyance direction of the recording medium. Already known. When a line head (long head) having a large number of nozzles is manufactured as an integrated / single recording head, the yield decreases and expensive manufacturing equipment is required (ex. Large-diameter silicon process apparatus). There are problems such as.

  In view of this, a technique has been disclosed in which a plurality of recording head units having a relatively small number of nozzles are arranged in a line to increase the length. For example, in Patent Document 1, a plurality of element substrates provided with pressure generating elements are arranged in a line on a base plate made of metal or the like and bonded and fixed, and a support member including a nozzle and an ink flow path is provided on the element substrate. Bonded to realize a long head.

  Further, Patent Document 2 adopts a method in which recording head units are aligned and joined without using a base plate. In addition, Patent Document 3 discloses a structure in which recording head units are arranged in a staggered manner on a frame.

  Each technique is a method in which an element substrate having the lowest yield among the component parts is manufactured by dividing the unit into units (not integrally manufactured), and it is essential that adjacent units are mutually positioned with high precision.

  As a method for positioning such a recording head unit, a method based on the outer shape of each recording head unit, a method based on a special alignment mark, a method based on a nozzle that actually ejects droplets, etc. After use and alignment at a predetermined position, the long head is configured by bonding and fixing to the base plate using an adhesive or the like.

On the other hand, inside the droplet discharge recording apparatus to which the long head thus manufactured is mounted, the storage environment change of the droplet discharge recording apparatus, the surrounding environment during use, the motor existing in the droplet discharge recording apparatus, etc. The temperature varies depending on the heat-generating component.
JP-A-10-181004 JP 2003-266710 A JP 2001-199074 A

  In view of the above facts, the present invention provides a droplet discharge device that maintains a fixed position in each recording head unit even when the environmental temperature changes.

  According to the first aspect of the present invention, in the droplet discharge device, a plurality of droplet discharge head units that discharge droplets from nozzles and the plurality of droplet discharge head units are arranged, and the droplet discharge head unit Also, the thermal expansion coefficient is small, the support member that supports both ends, and the both ends of the droplet discharge head are fixed from the support member in the direction intersecting the direction in which the droplet discharge heads are arranged. And an expansion / contraction means provided on the attachment member and extending / contracting due to a difference in thermal expansion between the droplet discharge head and the support member.

  According to a second aspect of the present invention, in the droplet discharge device according to the first aspect, the attachment member is an attachment piece integrally formed on the support member so as to protrude from the support member. And

  According to a third aspect of the present invention, in the droplet discharge device according to the first aspect, the attachment member is a plate member fixed to the support member so as to protrude from the support member. .

  According to a fourth aspect of the present invention, in the liquid droplet ejection device according to any one of the first to third aspects, the expansion / contraction means is mounted on one of the mounting members that protrudes from both sides of the support member. It was provided in the member.

  According to a fifth aspect of the present invention, in the droplet discharge device according to any one of the first to fourth aspects, the expansion / contraction means is a low-rigidity portion having a lower rigidity than other portions of the mounting member. It is characterized by that.

  According to a sixth aspect of the present invention, in the liquid droplet ejection device according to the fifth aspect, the low-rigidity portion is configured by forming a through hole in the attachment member.

  According to a seventh aspect of the present invention, in the liquid droplet ejection apparatus according to the fifth or sixth aspect, the low-rigidity portion is configured by forming a notch in the mounting member.

  According to an eighth aspect of the present invention, in the droplet discharge device according to any one of the fifth to seventh aspects, the low-rigidity portion is formed on the mounting member and is thinner than other portions. It is a thin part.

  According to a ninth aspect of the present invention, in the droplet discharge device according to any one of the fifth to eighth aspects, the low-rigidity portion is a bellows structure formed on the mounting member. .

  According to a tenth aspect of the present invention, in the liquid droplet ejection apparatus according to any one of the fifth to ninth aspects, the rigidity of the low-rigidity portion is 5 times or less the rigidity of the liquid droplet ejection head. It is characterized by that.

  According to an eleventh aspect of the present invention, in the liquid droplet ejection apparatus according to any one of the first to fourth aspects, the attachment means includes a base that is fixed to the support member, and the recording head unit is fixed. And the elastic member is a spring means for connecting the base and the free end.

  According to a twelfth aspect of the present invention, in the liquid droplet ejection apparatus according to any one of the first to fourth aspects, the attachment means includes a base portion that is fixed to the support member, and the recording head unit is fixed. And the telescopic member has a fitting structure in which the free end portion is slidably engaged with the base portion.

  According to the first to third aspects of the present invention, the expansion / contraction difference due to the temperature change between the support member and the droplet discharge head can be absorbed by the expansion / contraction means, and the recording head unit positions the support member even if the environmental temperature changes. A fixed state is maintained.

  In the fourth aspect of the invention, the direction of fluctuation of the droplet discharge head due to temperature change is constant.

  In the invention according to claims 5 to 10, the low rigidity portion can be deformed and expanded and contracted by providing the attachment member with the low rigidity portion.

  In the invention described in claim 11, the free end portion of the mounting member can be expanded and contracted by the spring means.

  In the invention according to claim 12, the free end portion of the mounting member can be slid by the fitting structure.

  Hereinafter, an ink jet recording apparatus as a droplet discharge apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows an ink jet recording apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, the ink jet recording apparatus 10 stocks the paper P and sends it to the recording head unit 16 by controlling the posture of the paper P supplied from the paper supply unit 12 and the paper supply unit 12 sent out during image recording. The registration unit 14 includes a registration adjustment unit 14, a recording head unit 16 that records ink by ejecting ink droplets onto the paper P sent from the registration adjustment unit 14, and a maintenance unit 18 that performs maintenance of the recording head unit 16. 20 and a discharge unit 22 that discharges the paper P on which an image is recorded by the recording unit 20.

  The paper supply unit 12 is provided with a stocker 24 in which a plurality of sheets P are stacked and stocked, and a transport device 26 that transports the sheets one by one from the stocker 24 to the registration adjusting unit 14.

  The registration adjusting unit 14 is provided with a loop forming unit 28 and a guide member 29 for controlling the posture of the paper. The paper P fed from the paper supply unit 12 is supplied with the loop forming unit 28 and the guide member. By passing through 29, the skew of the paper P is corrected using the stiffness of the paper P, and the conveyance timing is controlled and sent to the recording unit 20.

  In the recording unit 20, a recording head unit 16 and a maintenance unit 18 that are vertically opposed to each other are provided, and a sheet conveyance path through which the sheet P fed from the registration adjusting unit 14 is conveyed is formed between them. Yes. The recording head unit 16 is provided with a plurality of inkjet recording heads 30 arranged at a predetermined interval along the paper conveyance path, and on the upstream side and the downstream side of each inkjet recording head 30 in the paper conveyance path, A plurality of pairs of star wheels 17 and transport rolls 19 which are vertically opposed to each other are provided.

  The paper P is transported continuously (without stopping) on the paper transport path while being sandwiched between the star wheel 17 and the transport roll 19, and ink droplets are ejected from each ink jet recording head 30 of the recording head unit 16. As a result, an image is recorded. In the discharge unit 22, the paper P on which an image is recorded by the recording unit 20 is conveyed by the paper discharge belt 23 and stored in the tray 25.

  The maintenance unit 18 includes a maintenance device 21 that is disposed so as to face the ink jet recording head 30, and performs processes such as capping, wiping, and preliminary discharge and suction on the ink jet recording head 30.

  Next, the ink jet recording head 30 mounted on the ink jet recording apparatus 10 will be described in detail.

  As shown in FIGS. 2 and 3A and 3B (note that FIGS. 3A and 3B are conceptual diagrams of FIG. 2), the inkjet recording head 30 is orthogonal to the paper feed direction X. A plurality of recording head units 32 arranged along the direction (paper width direction Y) is provided.

  As shown in FIG. 3B, the recording head unit 32 is formed with a plurality of nozzles 74 in a line shape along the paper width direction Y, and the recording head unit 32 continuously passes the paper transport path. An image is recorded on the paper P by ejecting ink droplets from the nozzles 74 to the paper P conveyed to the paper.

  Note that at least four ink jet recording heads 30 mounted on the ink jet recording apparatus 10 are arranged corresponding to each color of YMCK in order to record a so-called full-color image, for example.

  As shown in FIG. 4, the print area width by the nozzles 74 formed in a line on one ink jet recording head 30 is the maximum paper width PW of the paper P on which image recording with this ink jet recording apparatus 10 is assumed. The image recording over the entire width of the paper P is possible without moving the inkjet recording head 30 in the paper width direction Y (so-called Full Width Array (FWA)).

  Here, the print area is basically the largest of the recording areas obtained by subtracting the non-printing margin from both ends of the paper P, but is generally larger than the maximum paper width PW to be printed. . This is because there is a possibility that the sheet is conveyed at an angle (skew) with respect to the conveyance direction, and there is a high demand for borderless printing.

  As shown in FIGS. 2 and 3A and 3B, the inkjet recording head 30 includes a support member 40, and a plurality of recording head units 32 arranged along the longitudinal direction of the support member 40. It is comprised including.

  The support member 40 is made of aluminum (the material is preferably a high thermal conductive material, and in addition to aluminum, a metal material such as stainless steel, copper, titanium, or a high thermal conductive resin may be used). It is long in the paper width direction Y. A pair of attachment plates 41 are provided at both ends in the longitudinal direction of the support member 40, and the pair of attachment plates 41 are attached to a frame (not shown) of the inkjet recording apparatus 10.

  Furthermore, a plurality of openings 40A are formed at predetermined intervals along the longitudinal direction of the support member 40 at the center in the width direction of the support member 40, and an ink tank (not shown) is formed in the opening 40A. An ink supply unit 44 for supplying ink to the recording head unit 32 is disposed, and ink is supplied into the ink supply unit 44 through an ink tank relay tube (not shown).

  A pair of plate-like spacer members (intermediate members) 42 having a substantially L-shaped cross section are fixed to both side walls along the longitudinal direction of the support member 40, and are supported. It protrudes from the side wall of the support member 40 along the width direction of the member 40. The spacer member 42 is screwed to the support member 40 at two locations by screws 46 and can be removed from the support member 40.

  A pair of spacer members 42 corresponding to each recording head unit 32 are arranged in a state of being separated from each other, and an ink supply unit 44 is arranged between the spacer member 42 and the spacer member 42.

  In this way, by disposing the two spacer members 42 apart from each other, it is not necessary to provide the ink supply flow path in the spacer member 42 itself, and the ink supply unit 44 can be disposed in the separated portion. A supply path can be secured. Furthermore, since there is no need to form an ink supply path in the spacer member 42, it is possible to select a material that does not take ink resistance into consideration, and a degree of freedom can be obtained in selecting a material to be used for the spacer member 42.

  Here, the case where two spacer members separated from each other are used for each recording head unit 32 is described. However, the present invention is not limited to this embodiment. For example, the ink supply unit uses one spacer member. The form which forms a through-hole in the part which arrange | positions 44 may be sufficient.

  On the other hand, as shown in FIG. 5 and FIG. 6A, a bonding region 129 to which a UV (ultraviolet) curable adhesive U is bonded is provided on the back surface of the spacer member 42 on the free end side. Then, the recording head unit 32 to which the adhesive U is applied is bonded to the bonding region 129, so that the recording head unit 32 is fixed to the spacer member 42.

  Here, a gap G corresponding to the thickness of the adhesive U is formed between the recording head unit 32 and the spacer member 42. By adjusting the gap G, the nozzle surfaces of the plurality of recording head units 32 are formed. The height of 52A is aligned.

  Further, on the inner side of the adhesion region 129 of the spacer member 42 (the central portion in the protruding direction of the spacer member 42), a plurality of rectangular through holes 130 are staggered so as to be staggered along the width direction of the spacer member 42. A low-rigidity portion 132 is provided, and the rigidity is lower than other portions of the spacer member 42 (the free end side and the base portion side of the spacer member 42).

  Incidentally, as shown in FIGS. 7A and 7B, the recording head unit 32 includes an ink supply relay member 50 and a head substrate (element substrate) 52. The ink supply relay member 50 is disposed on the spacer member 42 side, and an individual supply path 50A that is connected to the ink supply unit 44 and supplies ink to each nozzle 74 (see FIG. 8) is formed therein.

  As shown in FIG. 8, the head substrate 52 is provided with a nozzle plate 72, and nozzles 74 for ejecting ink droplets are formed in one row in the paper width direction Y on the nozzle plate 72 (FIG. 3). (See (B)). The surface of the nozzle plate 72 on which the nozzles 74 are formed is a nozzle surface 52A, and the nozzle surface 52A is subjected to a liquid repellency process.

  Here, an example in which the nozzles are formed in the head substrate 52 in a line in the paper width direction Y has been described, but the present invention is not limited thereto. For example, nozzles may be formed on the head substrate 52 so as to form a matrix array on a two-dimensional plane in the paper width direction Y and the paper feed direction X in order to improve image quality and speed.

  On the upper surface of the nozzle plate 72, a communication hole plate 76, a damper member 78, pool plates 80, 82, 84, a communication hole plate 86, flow channel plates 88, 90, a pressure chamber plate 92, and a vibration plate 94 are arranged in order from the bottom. The communication hole plate 76 is formed with a communication hole 96 communicating with the nozzle 74, and the damper member 78 is formed with a communication hole 98.

  Further, communication holes 100, 102, and 104 are formed in the pool plates 80, 82, and 84, respectively, and a communication hole 106 is formed in the communication hole plate 86. Furthermore, a communication hole 108 is formed in the flow path plate 88, and a communication hole 110 is formed in the flow path plate 90. These nozzles 74 and communication holes 96, 98, 100, 102, 104, 106, 108, 110 communicate with each other and are connected to a pressure chamber 112 formed in the pressure chamber plate 92.

  On the other hand, the communication hole plate 76 has a cavity 114 formed below the damper member 78. The pool plates 80, 82, and 84 are formed with ink pools 116, 118, and 120, respectively, that store ink supplied from an ink supply unit (not shown) through ink supply holes (not shown). Further, a supply hole 122 is formed in the communication hole plate 86, an ink flow path 124 is formed in the flow path plate 88, and a supply hole 126 is formed in the flow path plate 90.

  The ink pools 116, 118, 120, the supply hole 122, the ink flow path 124, the supply hole 126, and the pressure chamber 112 communicate with each other, and the ink pool 116, 118, 120 communicates with the inside of the pressure chamber 112. Ink is supplied.

  In addition, a piezoelectric element 128 is attached to the upper portion of the vibration plate 94 above each pressure chamber 112 communicating with each nozzle 74, and a flexible wiring board (not shown) joined to the upper portion of the piezoelectric element 128. The driving voltage is applied from the above.

  When a driving voltage is applied to the piezoelectric element 128, the vibration plate 94 is deformed in the vertical direction due to the bending deformation of the piezoelectric element 128, and the ink filled in the pressure chamber 112 is pressurized, and the ink is supplied from the nozzle 74. Drops are ejected.

  Next, a method for manufacturing the recording head unit 32 according to the embodiment of the present invention will be described.

  First, electrode layers are formed on both sides of a plate-like piezoelectric body (thickness of about 30 μm) processed to a required thickness. Next, the piezoelectric body is individualized by means such as a blast method or a dicing method so that the cross section of the deposited electrode layer and the piezoelectric body is exposed and corresponds to each nozzle 74 (pressure chamber 112), and the piezoelectric element 128 (FIG. 8).

  Then, by means such as adhesion, the nozzle plate 72, the communication hole plate 76, the damper member 78, the pool plates 80, 82, 84, the communication hole plate 86, the flow path plates 88, 90, the pressure chamber plate 92, and the like shown in FIG. The diaphragm 94 is joined, and the piezoelectric element 128 is joined to the diaphragm 94. Furthermore, a flexible wiring board is connected to the high potential application surface side electrode (upper surface in FIG. 8) of the piezoelectric element 128 via an electrical contact such as solder bonding.

  Then, the ink supply relay member 50 and the ink supply unit 44 (see FIG. 2) for supplying the ink supplied from the ink tank to the ink pools 116, 118, and 120 are attached. Thus, the recording head unit 32 is completed.

  Next, the UV curable adhesive U is applied to each recording head unit 32, and the recording head unit 32 is brought into close contact with the spacer member 42 provided on the support member 40. In this state, UV light is irradiated between the spacer member 42 and the recording head unit 32, and the adhesive U is cured while maintaining the positional accuracy between the spacer member 42 and the recording head unit 32, so that the recording head unit 32 is moved to the spacer. Secure to member 42. If necessary, a reinforcing adhesive may be applied and cured.

  Next, the operation of the ink jet recording apparatus 10 of this embodiment will be described.

  When a print job is input to the inkjet recording apparatus 10 shown in FIG. 1 and a printing (image recording) operation is started, one sheet P is picked up from the stocker 24 and conveyed to the recording unit 20 by the conveying device 26. .

  On the other hand, ink is already injected (filled) into the ink jet recording head 30 from the ink tank to the individual supply path 50A (see FIG. 7A) of the recording head unit 32 via the ink supply port. At this time, a meniscus having a slightly recessed ink surface is formed at the tip (discharge port) of the nozzle 74 (see FIG. 8).

  An image based on the image data is recorded on the paper P by selectively ejecting ink droplets from the plurality of nozzles 74 of the recording head unit 32 while transporting the paper P at a predetermined transport speed.

  By the way, in this embodiment, as shown in FIG. 5 and FIG. 6 (A), a plurality of rectangular through holes 130 are formed in the spacer member 42, and the low rigidity portion is lower in rigidity than the other portions of the spacer member 42. 132 is provided.

  Here, the support member 40 and the spacer member 42 are made of metal, but the recording head unit 32 is made of a composite of resin and metal. Since the thermal expansion coefficient differs between the metal and the resin, if the spacer member 42 and the recording head unit 32 are thermally expanded due to a temperature rise, as shown in FIGS. 9A and 9B, the spacer member 42 and the recording head. Due to the difference in thermal expansion between the unit 32 and the adhesive U, a tensile stress F directed outward (in the direction of the arrow) is applied to the adhesive U via the recording head unit 32.

  Next, when the temperature falls (when returning to room temperature), as shown in FIG. 9C, the spacer member 42 and the recording head unit 32 try to return to the original state. The stress F ′ toward the inside (in the direction of the arrow) acts on the adhesive U due to the shrinkage difference generated between the tensile stress F and the adhesive U as a so-called residual stress. Therefore, the stress F ′ in the direction opposite to the tensile stress F (hereinafter referred to as “compressive stress F ′” for convenience of explanation) acts (so-called irreversible deformation).

  For this reason, when the temperature change is repeated, the relative positional relationship between the spacer member 42 and the recording head unit 32 shifts as shown in FIGS. 10A and 10B, or as shown in FIG. There is a concern that the adhesive U is peeled off from the recording head unit 32 and the recording head unit 32 is detached from the spacer member 42.

  Therefore, in the present embodiment, as shown in FIGS. 5 and 6A, when the plurality of through holes 130 are formed in the spacer member 42 that fixes the recording head unit 32, the through holes 130 are not formed. The rigidity of the spacer member 42 is lower than that of the spacer member 42. Thereby, the spacer member 42 is easily deformed.

  As shown in FIGS. 9A and 9B, the tensile stress F is applied to the spacer member 42 via the adhesive U due to the difference in thermal expansion between the spacer member 42 and the recording head unit 32 due to the temperature rise. As shown in FIGS. 6A and 6B, the low rigidity portion 132 expands following the deformation of the recording head unit 32 via the adhesive U as shown in FIGS.

  Thereby, the difference in thermal expansion generated between the spacer member 42 and the recording head unit 32 is reduced, and the tensile stress F is absorbed (reduced). Here, the deformation of the low-rigidity portion 132 is within the elastic deformation region of the low-rigidity portion 132.

  Next, when the temperature returns to normal temperature, as shown in FIGS. 9B and 9C, the spacer member is interposed via the adhesive U due to the shrinkage difference generated between the spacer member 42 and the recording head unit 32. Compressive stress F ′ acts on 42, but the low rigidity portion 132 contracts following the deformation of the recording head unit 32 via the adhesive U. Thereby, the shrinkage difference generated between the spacer member 42 and the recording head unit 32 is reduced, and the compressive stress F ′ is absorbed (reduced).

  As described above, since the difference in thermal expansion (shrinkage) between the spacer member 42 and the recording head unit 32 can be absorbed by expanding and contracting the low-rigidity portion 132 of the spacer member 42, the adhesive U uses the heat. Residual strain due to expansion (shrinkage) difference is reduced. For this reason, it is possible to prevent the adhesive U from coming off and to position and fix each recording head unit 32 with high accuracy.

  Here, as shown in FIGS. 11A and 11B, a two-layer model composed of different materials 1 and 2 is considered. Since the expression becomes complicated, the vertical displacement of the length L is ignored.

  When the materials 1 and 2 are in a free state, when the temperature difference ΔT is given to the whole, the lengths L1 'and L2' of the materials 1 and 2 are as follows.

L1 ′ = L1 + ΔL1 (1)
L2 ′ = L2 + ΔL2 (2)
Here, when the thermal expansion coefficients of the materials 1 and 2 are α1 and α2, respectively, the following is obtained.

ΔL1 = α1 × L1 × ΔT = α1 × L2 × (L1 / L2) × ΔT (3)
ΔL2 = α2 × L2 × ΔT (4)
When the temperature difference ΔT is given while the material 1 and the material 2 are bonded,
L1 ′ + ΔL1 ′ + (L2−L1) = L2′−ΔL2 ′ (5)
When substituting (1) to (4) into (5),
ΔL1 ′ + ΔL2 ′ = L2′−L1 ′ − (L2−L1)
= L2 + ΔL2- (L1 + ΔL1)-(L2-L1)
= Α2 × L2 × ΔT−α1 × L2 × (L1 / L2) × ΔT
= {Α2- (L1 / L2) α1} × L2 × ΔT (6)
It becomes. Dividing both sides of this equation (6) by L2,
(ΔL1 ′ / L2) + (ΔL2 ′ / L2) = {α2− (L1 / L2) α1} × ΔT (7)
It becomes. Here, when the strains of the materials 1 and 2 at this time are ε1 and ε2,
ε1 = ΔL1 ′ / L1 = ΔL1 ′ / {L2 × (L1 / L2)}
Therefore,
ΔL1 ′ / L2 = (L1 / L2) × ε1 (8)
ε2 = ΔL2 ′ / L2 (9)
From the equations (7) to (9), the following is obtained.

(L1 / L2) × ε1 + ε2 = {α2− (L1 / L2) α1} × ΔT (10)
On the other hand, the stresses F1 and F2 generated in the materials 1 and 2 are F1 = E1 × ε1 × t1 (11) where the Young's modulus of the materials 1 and 2 is E1 and E2 and the thicknesses are t1 and t2.
F2 = E2 × ε2 × t2 (12)
It becomes.

F1 = F2 (13)
So, from equations (11) to (13),
E1 × ε1 × t1 = E2 × ε2 × t2 (14)
It becomes. Here, from equation (10),
ε2 = {α2− (L1 / L2) α1} × ΔT− (L1 / L2) × ε1
It becomes. Substituting this into equation (14)
E1 × ε1 × t1
= E2 × ε2 × t2
= E2 * t2 * {[alpha] 2- (L1 / L2) [alpha] 1} * [Delta] T-E2 * t2 * (L1 / L2) * [epsilon] 1
Therefore,
{E1 × t1 + E2 × t2 × (L1 / L2)} × ε1
= E2 * t2 * {[alpha] 2- (L1 / L2) [alpha] 1} * [Delta] T
That is,
ε1 = {E2 × t2 × {α2− (L1 / L2) α1} × ΔT} / {E1 × t1 + E2 × t2 × (L1 / L2)} (15)
When substituting equation (15) into equation (11),
F = F1 = F2 = E1 × ε1 × t1
= E1 * t1 * {E2 * t2 * {[alpha] 2- (L1 / L2) [alpha] 1} * [Delta] T} / {E1 * t1 * + E2 * t2 * (L1 / L2)}
It becomes. That is,

ここで、スペーサ部材４２の幅Ｌ１を１５ｍｍとし、厚みをｔ１とする。このスペーサ部材４２のヤング率Ｅ１は７０ＧＰａであり、熱膨張係数α１は２４ｐｐｍである。また、記録ヘッドユニット３２の幅Ｌ１を２２．５ｍｍとし、厚みｔ２を１０ｍｍとする。この記録ヘッドユニット３２のヤング率Ｅ２は１．４４ＧＰａ（＝２．２５Ｇｐａ×体積占有率０．６４）であり、熱膨張係数α２は８０ｐｐｍである。

Here, the width L1 of the spacer member 42 is 15 mm, and the thickness is t1. The spacer member 42 has a Young's modulus E1 of 70 GPa and a thermal expansion coefficient α1 of 24 ppm. The recording head unit 32 has a width L1 of 22.5 mm and a thickness t2 of 10 mm. The Young's modulus E2 of the recording head unit 32 is 1.44 GPa (= 2.25 Gpa × volume occupation ratio 0.64), and the thermal expansion coefficient α2 is 80 ppm.

  From the equation (16), the ratio of the rigidity (E1t1) of the spacer member 42 to the rigidity (E2t2) of the recording head unit 32, the so-called rigidity ratio (E1t1 / E2t2), and the thermal expansion difference between the spacer member 42 and the recording head unit 32. FIG. 12 shows the relationship with the tensile stress F applied to the adhesive U due to the above.

  As shown in FIG. 12, the thickness t1 of the spacer member 42 is changed (the rigidity of the spacer member 42 is changed), the rigidity ratio (E1t1 / E2t2) between the spacer member 42 and the recording head unit 32, and the tensile stress to the adhesive U From the relationship with F, it can be seen that when the rigidity ratio (E1t1 / E2t2) is 5 or less, the tensile stress F rapidly decreases and the generation of the tensile stress F becomes smaller.

  That is, by setting the rigidity of the spacer member 42 to 5 times or less than the rigidity of the recording head unit 32, the spacer member 42 extends following the deformation of the recording head unit 32 via the adhesive U, and the spacer The difference in thermal expansion generated between the member 42 and the recording head unit 32 can be reduced, and the tensile stress F is reduced.

  Since the rigidity of the low-rigidity portion 132 of the spacer member 42 only needs to be close to the rigidity of the recording head unit 32, the rigidity ratio of the low-rigidity portion 132 of the recording head unit 32 and the spacer member 42 is about 1 time. preferable.

  In FIG. 13, the thickness t1 of the spacer member 42 is set to 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, and 5.0 mm, and each spacer member 42 is along the protruding direction of the spacer member 42. The ratio of the area of the part where the through hole 130 is not formed to the total area (S1) (the area (S2) of the part where the through hole 130 is formed), the so-called area ratio ((S1-S2) / S1) The relationship between the tensile stress F applied to the adhesive U due to the difference in thermal expansion between the spacer member 42 and the recording head unit 32 is shown.

  According to this, by setting the area of the through hole 130 of the spacer member 42 according to the thickness t1 of the spacer member 42, the rigidity of the spacer member 42 sufficient to reduce the tensile stress F can be selected.

  In the present embodiment, as shown in FIG. 5, a plurality of rectangular through holes 130 are formed in the center portion of the spacer member 42 in the protruding direction so that the rigidity is lower than the free end side and the base side of the spacer member 42. Although the low-rigidity portion 132 is provided, it is only necessary that the low-rigidity portion 132 can be provided on the spacer member 42. Therefore, the present invention is not limited to this.

  For example, as shown in FIGS. 14, 15 </ b> A, and 15 </ b> B, the width direction (support) of the spacer member 134 is formed on the front and back surfaces of the central portion in the protruding direction (width direction of the support member 40) of the spacer member 134. The recesses 136 and 138 extending along the longitudinal direction of the member 40 are formed, and the recesses 136 and 138 are alternately arranged along the extending direction of the spacer member 42 to form a so-called bellows structure low-rigidity portion 140. You may do it.

  According to this, as shown in FIGS. 15A and 15B, when the spacer member 134 and the recording head unit 32 are thermally expanded due to the temperature rise, the thermal expansion difference between the spacer member 42 and the recording head unit 32 is caused. A tensile stress F acts on the spacer member 42 via the adhesive U.

  For this reason, following the deformation of the recording head unit 32 via the adhesive U, the entrance side of the recesses 136 and 138 of the low-rigidity portion 140 expands, and the low-rigidity portion 140 extends. Thereby, the thermal expansion difference generated between the spacer member 134 and the recording head unit 32 is reduced, and the tensile stress F is reduced.

  Then, when the spacer member 134 and the recording head unit 32 contract when the temperature returns to room temperature, a compressive stress is applied to the spacer member 134 via the adhesive U due to a contraction difference between the spacer member 134 and the recording head unit 32. F 'acts.

  Therefore, the inlet side of the recesses 136 and 138 of the low-rigidity portion 140 is restored following the deformation of the recording head unit 32 via the adhesive U, and the low-rigidity portion 140 contracts. The shrinkage difference generated between the recording head unit 32 and the compressive stress F ′ is reduced.

  In this embodiment, as shown in FIG. 2, a spacer member 42 is provided for each recording head unit 32 on the side wall along the longitudinal direction of the support member 40, and each recording head unit 32 is bonded and fixed to the spacer member 42. However, the spacer member 42 is not always necessary.

  For example, as shown in FIGS. 16 and 17A and 17B, a thin flange 142 is extended from the lower portion of the side wall in the longitudinal direction of the support member 40, and a plurality of rectangular through holes 144 are formed in the flange 142. May be provided to provide a low-rigidity portion 146, and each recording head unit 32 may be bonded and fixed to the free end side of the flange 142.

  As shown in FIGS. 17A and 17B, when the flange 142 and the recording head unit 32 are thermally expanded due to the temperature rise, the adhesive U is interposed due to the difference in thermal expansion between the flange 142 and the recording head unit 32. Since the tensile stress F acts on the flange 142, the low-rigidity portion 146 extends following the deformation of the recording head unit 32 via the adhesive U. Thereby, the thermal expansion difference generated between the flange 142 and the recording head unit 32 is reduced, and the tensile stress F is reduced.

When the flange 142 and the recording head unit 32 contract when the temperature returns to normal temperature, a compressive stress F ′ acts on the flange 142 via the adhesive U due to a contraction difference between the flange 142 and the recording head unit 32. Therefore, the low rigidity portion 146 contracts following the deformation of the recording head unit 32 through the adhesive U. Thereby, the shrinkage difference generated between the flange 142 and the recording head unit 32 is reduced, and the compressive stress F ′ is reduced.
(Second Embodiment)
Next, the gist of the second embodiment will be described. In addition, description is abbreviate | omitted about the content substantially the same as 1st Embodiment.

  In the present embodiment, as shown in FIGS. 18 to 20A and 20B, notch portions 150 are provided on both sides along the width direction of the spacer member 148 inside the adhesion region 129 of the spacer member 148. In addition, a low-rigidity portion 154 in which a plurality of rhombus-shaped (parallelogram) through holes 152 are formed is provided between the notch portion 150 and the notch portion 150.

  Thus, by providing the notch 150 in the width direction of the spacer member 148, the rigidity of the low-rigidity part 154 can be further reduced as compared with the case where the notch 150 is not formed.

  Moreover, the crosspiece 156 which connects the through-hole 152 and the through-hole 152 will be in the state which had an angle with respect to the tensile stress F mentioned later by making the through-hole 152 into a rhombus. For this reason, as shown in FIG. 5, compared with the case where the through-hole 130 is rectangular, no stress is applied in the direction in which the through-hole 130 is stretched with respect to the tensile stress F (the direction perpendicular to the tensile stress F). The through hole 152 is easily deformed. That is, the low-rigidity portion 154 is easily expanded and contracted.

  Here, the notched portion 150 is provided in the low-rigidity portion 154, and a plurality of rhomboidal through holes 152 are formed between the notched portion 150 and the notched portion 150. However, as shown in FIG. A plurality of through holes 130 may be provided. As described above, when the rhombic through-hole 152 and the rectangular through-hole 130 are compared, the rectangular through-hole 130 is more difficult to deform than the rhomboid through-hole 152. In the case of forming a rectangular shape, as shown in FIGS. 22A and 22B, the low rigidity portion 155 may be thin. Thereby, the rigidity of the low rigidity part 155 becomes low, and the low rigidity part 155 becomes easy to deform | transform.

  Here, as shown in FIG. 19, the plurality of through holes 152 are formed as the low-rigidity portion 154, but it is only necessary that the low-rigidity portion 154 is provided in the spacer member 148 and the low-rigidity portion 154 can be expanded and contracted. Therefore, the through hole 152 is not necessarily required. The same applies to the first embodiment.

  For example, as shown in FIGS. 23 and 24, low-rigidity portions 164 in which concave portions 160 and 162 are alternately formed along the protruding direction of the spacer member 158 are formed on the front and back surfaces of the spacer member 158.

  As shown in FIGS. 24A and 24B, when the spacer member 158 and the recording head unit 32 are thermally expanded due to a temperature rise, the adhesive U is applied by the difference in thermal expansion between the spacer member 158 and the recording head unit 32. Accordingly, the tensile stress F in the direction of the arrow acts on the spacer member 158.

  As a result, following the deformation of the recording head unit 32 via the adhesive U, the entrance sides of the recesses 160 and 162 of the low-rigidity portion 164 expand, and the low-rigidity portion 164 extends. For this reason, the difference in thermal expansion between the spacer member 158 and the recording head unit 32 is reduced, and the tensile stress F is reduced.

  Then, when the spacer member 158 and the recording head unit 32 contract when the temperature returns to room temperature, a compressive stress F is applied to the spacer member 158 via the adhesive U due to a contraction difference between the spacer member 158 and the recording head unit 32. 'Acts.

  As a result, the inlet side of the recesses 160 and 162 of the low-rigidity part 164 is restored following the deformation of the recording head unit 32 via the adhesive U, and the low-rigidity part 164 contracts. For this reason, the shrinkage difference between the spacer member 158 and the recording head unit 32 is reduced, and the compressive stress F ′ is reduced.

  In the above embodiments, the recording head unit 32 is arranged along the width direction of the support member 40. However, as shown in FIG. 25, an angle is provided with respect to the width direction of the support member 40. The recording head unit 166 may be arranged in a state.

  In this case, as shown in FIG. 25 and FIGS. 26A and 26B, when the spacer member 158 and the recording head unit 166 are thermally expanded due to the temperature rise, they are generated between the spacer member 158 and the recording head unit 166. Due to the difference in thermal expansion, a tensile stress F in the direction of the arrow acts on the spacer member 158 via the adhesive U. Further, since the recording head unit 166 is asymmetric with respect to the straight line P passing through the center of gravity G, the recording head unit 166 generates a moment M around the center of gravity G in the arrow direction.

  That is, due to the thermal expansion difference generated between the spacer member 158 and the recording head unit 166, the adhesive U is subjected to stress in the XY directions due to the tensile stress F and the moment M generated by the recording head unit 166. Since the through hole 152 constituting the low-rigidity portion 154 has a rhombus shape, the through hole 152 can be deformed in the X direction and the Y direction by substantially the same stress.

  For this reason, the low-rigidity portion 154 follows the deformation of the recording head unit 166 and extends in the XY direction via the adhesive U, and the thermal expansion generated between the spacer member 158 and the recording head unit 166. The difference becomes smaller, and the stress in the XY direction due to the tensile stress F and moment M is reduced.

  When the spacer member 158 and the recording head unit 166 contract when the temperature returns to the normal temperature, the spacer member 158 has the adhesive member U via the adhesive U due to a contraction difference generated between the spacer member 158 and the recording head unit 166. The stress in the XY direction is applied by the moment in the direction opposite to the compressive stress F ′ and the moment M.

  For this reason, the low-rigidity portion 154 follows the deformation of the recording head unit 166 and contracts in the XY direction via the adhesive U. Therefore, the thermal expansion difference generated between the spacer member 158 and the recording head unit 166. The stress in the XY direction due to the moment in the direction opposite to the compressive stress F ′ and the moment M is reduced.

  That is, in the case of the recording head unit 166 arranged with an angle with respect to the width direction of the support member 40, the low-rigidity portion 154 not only expands and contracts in one direction (Y direction) but also has an elastic effect in the XY direction. By holding and expanding and contracting, irreversible shift can be suppressed, and position accuracy at room temperature is ensured.

  In these embodiments, the low-rigidity portions 132, 154, 164 are formed by providing the through holes 130, 156 or the recesses 160, 162 in the center of the spacer members 42, 148, 158 in the protruding direction. The low-rigid portions 132, 154, and 164 were expanded and contracted by deforming the through holes 130 and 156 and the recesses 160 and 162. However, the spacer members 42, 148, and 158 may be expanded and contracted. It is not limited.

  For example, as shown in FIGS. 27 and 28A and 28B, the spacer member 168 includes a free end 168A side to which the recording head unit 32 is fixed, and a base 168B side to which the support member 40 is fixed. The spring member 170 is disposed in the center of the spacer member 168. Then, the spring member 170 may connect the free end portion 168A side and the base portion 168B side of the spacer member 168, and the spacer member 168 may be expanded and contracted by expansion and contraction of the spring member 170.

  29, 30A, and 30B, a slide member 174 that moves along the protruding direction of the spacer member 172 is provided on the spacer member 172, and the recording head unit 32 is attached to the slide member 174. It may be fixed.

  As shown in FIG. 30C, the spacer member 172 is formed with a groove portion 172A having an inverted triangular shape along the protruding direction of the spacer member 172, and the slide member 174 slides within the groove portion 172A. The slide member 174 is integrated with the spacer member 172 and is prevented from dropping in a state where the possible slide projection 174A is projected and the slide projection 174A is mounted in the groove 172A (fitting structure).

  Here, in order to prevent the fitting state between the slide protrusion 174A and the groove portion 172A from changing, the stress acting on the slide member 174 is set in one direction. That is, it is better to arrange the recording head unit 32 along the width direction of the support member 40.

  Further, the slide member 174 is provided with a tension spring 176 having one end attached to the support member 40, and biases the slide member 174 toward the support member 40. On the other hand, the spacer member 172 is provided with a stopper portion 178 to restrict the movement of the slide member 174.

  As shown in FIGS. 30A and 30B, when the recording head unit 32 is thermally expanded due to a temperature rise, a difference in thermal expansion between the spacer member 172 and the recording head unit 32 is caused to pass through the adhesive U. Thus, a tensile stress F in the direction of the arrow acts on the slide member 174.

  As a result, the slide member 174 moves in the direction against the urging force of the tension spring 176 following the deformation of the recording head unit 32 via the adhesive U. For this reason, the difference in thermal expansion generated between the recording head unit 32 and the slide member 174 is reduced, and the tensile stress F is reduced.

  Next, when the recording head unit 32 contracts when the temperature returns to the normal temperature, a compressive stress is applied to the slide member 174 via the adhesive U due to a contraction difference generated between the spacer member 172 and the recording head unit 32. F 'acts.

  Accordingly, the tension spring 176 is restored following the deformation of the recording head unit 32 via the adhesive U, and the slide member 174 moves. For this reason, the shrinkage difference generated between the recording head unit 32 and the slide member 174 is reduced, and the tensile stress F is reduced. The tension spring 176 is not always necessary.

  In addition to this, as shown in FIGS. 31 and 32A and 32B, a resin portion 182 made of the same material as that of the recording head unit 32 is provided in the adhesion region 129 of the spacer member 180 by integral molding or the like. Provided integrally on the back side of the member 180.

  Even if the recording head unit 32 is thermally expanded due to the temperature rise, the resin portion 182 is thermally expanded in the same manner as the recording head unit 32. Therefore, the difference in thermal expansion generated between the resin portion 182 and the recording head unit 32 is as follows. The tensile stress F acting on the resin portion 182 via the adhesive U is smaller than the difference in thermal expansion that occurs between the spacer member 180 and the recording head unit 32.

  When the recording head unit 32 contracts when the temperature returns to normal temperature, the resin portion 182 contracts in the same manner as the recording head unit 32, so that the difference in contraction that occurs between the resin portion 182 and the recording head unit 32 is The compressive stress F ′ acting on the resin portion 182 via the adhesive U is smaller than the shrinkage difference generated between the spacer member 180 and the recording head unit 32.

  In these embodiments, each spacer member 172 is provided with the low-rigidity portion 132. For example, as shown in FIGS. 33, 34A, and 34B, whichever of the pair of spacer members 184 is selected. The low rigidity portion 186 may be provided only on one of the spacer members 184A.

  Thus, on the spacer member 184A side where the low-rigidity portion 186 is formed, the recording head unit 32 absorbs the thermal expansion (contraction) difference between the spacer member 184 and the recording head unit 32 due to the temperature rise. Then, it moves (fluctuates) toward the spacer member 184A where the low-rigidity portion 186 is formed, and the fluctuation direction of the recording head unit 32 becomes constant.

  As mentioned above, although this invention was demonstrated in detail by embodiment mentioned above, this invention is not limited to those embodiment, Various other forms can be implemented within the scope of the present invention.

  For example, in the above-described embodiment, the example of the FWA corresponding to the paper width has been described. However, the ink jet recording head of the present invention is not limited to this, and the Partial Width Array (PWA) having a main scanning mechanism and a sub-scanning mechanism. It can also be applied to devices.

  In addition, in the inkjet recording apparatus 10 of the above embodiment, ink droplets are selectively ejected from the inkjet recording heads 30 of black, yellow, magenta, and cyan based on image data, and a full color image is recorded on the paper P. However, ink jet recording in the present invention is not limited to recording characters and images on the paper P.

  That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, industrially used liquids such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging solder in a welded state onto a substrate The ink jet recording head (droplet discharge head) according to the present invention can be applied to all droplet discharge (ejection) apparatuses.

1 is a schematic configuration diagram illustrating an overall configuration of an ink jet recording apparatus according to an embodiment of the present invention. 1 is a schematic perspective view of an ink jet recording head according to an embodiment of the present invention. 1A and 1B are conceptual diagrams of an ink jet recording head according to an embodiment of the present invention, in which FIG. It is a figure which shows the printing area | region by the inkjet recording head which concerns on embodiment of this invention. 1 is a plan view of an ink jet recording head according to a first embodiment of the present invention. (A), (B) is sectional drawing explaining the effect | action of the inkjet recording head which concerns on 1st Embodiment of this invention. 1A and 1B are conceptual diagrams of an inkjet recording head unit according to an embodiment of the present invention, in which FIG. FIG. 2 is a partial cross-sectional view illustrating an ink jet recording head unit according to an embodiment of the present invention. (A)-(C) are sectional drawings explaining the tensile stress which acts on the adhesive agent which fixes an inkjet recording head unit to a spacer member. It is sectional drawing explaining the content concerned about the tensile stress which acts on an adhesive agent. (A), (B) is explanatory drawing explaining how to obtain | require the tensile stress which acts on an adhesive agent. It is a graph which shows the relationship between the tensile stress which acts on an adhesive agent, and the rigidity ratio of the low-rigidity part of a spacer member. It is a graph which shows the relationship between the tensile stress which acts on an adhesive agent, and the area ratio of the low-rigidity part of a spacer member. It is a top view which shows the 1st modification of the inkjet recording head which concerns on 1st Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 1st modification of the inkjet recording head which concerns on 1st Embodiment of this invention. It is a perspective view which shows the 2nd modification of the inkjet recording head which concerns on 1st Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 2nd modification of the inkjet recording head which concerns on 1st Embodiment of this invention. It is a perspective view of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view which shows the 1st modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 1st modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view which shows the 2nd modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 2nd modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view which shows the 3rd modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 3rd modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view which shows the 4th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 4th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view which shows the 5th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 5th modification of the inkjet recording head based on 2nd Embodiment of this invention, (C) demonstrates the structure of a 5th modification. It is sectional drawing. It is a top view which shows the 6th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 6th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. It is a top view which shows the 7th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention. (A), (B) is sectional drawing explaining the effect | action of the 7th modification of the inkjet recording head which concerns on 2nd Embodiment of this invention.

Explanation of symbols

30 Inkjet recording head (droplet ejection device)
32 Recording head unit (Droplet ejection head unit)
40 Support member 42 Spacer member (plate material, mounting member)
130 Through-hole 132 Low rigidity part (extension / contraction means)
134 Spacer member (plate material, mounting member)
136 Concavity (bellows structure)
138 Concavity (bellows structure)
140 Low rigidity portion 142 Flange (Mounting piece, mounting member)
144 Through-hole 146 Low-rigidity portion 148 Spacer member (plate material, mounting member)
150 Notch portion 152 Through hole 154 Low rigidity portion 155 Low rigidity portion 158 Spacer member (plate material, mounting member)
160 Concave portion 162 Concave portion 164 Low-rigidity portion 166 Recording head unit (droplet discharge head unit)
168 Spacer member (plate material, mounting member)
168B Base (spacer member, plate material, mounting member)
168A Free end (spacer member, plate material, mounting member)
170 Spring member (spring means, expansion / contraction means)
172 Spacer member (plate material, mounting member)
172A Groove (fit structure, expansion / contraction means)
174A Slide protrusion (fitting structure, expansion / contraction means)
174 Slide member (free end, spacer member, plate material, mounting member)
180 Spacer member (plate material, mounting member)
184 Spacer member (plate material, mounting member)
184A Spacer member (plate material, mounting member)
186 Low rigidity part

Claims (12)

A plurality of droplet discharge head units for discharging droplets from the nozzles;
A support member in which the plurality of droplet discharge head units are arranged, the coefficient of thermal expansion is smaller than that of the droplet discharge head unit, and both ends are supported;
An attachment member that projects from both sides in a direction intersecting with the direction in which the droplet discharge heads are arranged from the support member, and which fixes both ends of the droplet discharge heads;
Extending / contracting means provided on the attachment member and extending / contracting due to a difference in thermal expansion between the droplet discharge head and the support member;
A droplet discharge apparatus comprising:   The droplet discharge device according to claim 1, wherein the attachment member is an attachment piece integrally formed with the support member so as to protrude from the support member.   The droplet discharge device according to claim 1, wherein the attachment member is a plate member fixed to the support member so as to protrude from the support member.   4. The droplet discharge device according to claim 1, wherein the expansion / contraction means is provided on one of the mounting members that protrudes from both sides of the support member. 5.   5. The droplet discharge device according to claim 1, wherein the expansion / contraction means is a low-rigidity portion having lower rigidity than other portions of the attachment member.   The liquid droplet ejection apparatus according to claim 5, wherein the low-rigidity portion is configured by forming a through hole in the attachment member.   The liquid droplet ejection apparatus according to claim 5, wherein the low-rigidity portion is configured by forming a notch in the attachment member.   The liquid droplet ejection apparatus according to claim 5, wherein the low-rigidity portion is a thin-walled portion that is formed on the mounting member and has a smaller thickness than other portions.   The liquid droplet ejection apparatus according to claim 5, wherein the low-rigidity portion has a bellows structure formed on the attachment member.   10. The droplet discharge device according to claim 5, wherein the rigidity of the low-rigidity part is five times or less of the rigidity of the droplet discharge head. The attachment means is divided into a base portion fixed to the support member and a free end portion to which the recording head unit is fixed,
The liquid droplet ejection apparatus according to claim 1, wherein the elastic member is a spring unit that connects the base and the free end. The attachment means is divided into a base portion fixed to the support member and a free end portion to which the recording head unit is fixed,
5. The droplet discharge device according to claim 1, wherein the elastic member has a fitting structure in which the free end portion is slidably engaged with the base portion.

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