DRIVE UNIT, DROPLET EJECTION HEAD AND DROPLET EJECTION DEVICE

Abstract

To provide a driving body unit which applies a proper pressure to a driving body even if relative dimensions of the driving body and a holding body vary.SOLUTION: A driving body unit includes: a driving body (a piezoelectric element 332) which is operated to expand or contract in a longitudinal direction; and a holding body 370 which may expand or contract in the longitudinal direction and holds the driving body in a driving body housing part 370d. The holding body has a contact member (a hollow set screw 380, 385) which is attached to a longitudinal end part of the holding body and contacts with an end part of the driving body. The holding body applies a pressure to the driving body.SELECTED DRAWING: Figure 5B

Description

[Technical field]

[0001] The present invention relates to a driver unit, and a droplet ejection head and a droplet ejection device that use the driver unit. [Background technology]

[0002] An example of an image forming apparatus equipped with a droplet ejection device is an inkjet printer described in Patent Document 1 (JP Patent Publication 2016-159501 A). An inkjet head (droplet ejection head) of this droplet ejection device is provided with an ejection nozzle for ejecting droplets toward a recording medium. A needle valve is disposed inside the ejection nozzle, and a driver (actuator) that expands and contracts in the longitudinal direction is connected to the needle valve.

[0003] The needle valve opens and closes as the driver expands and contracts (vibrates) in the longitudinal direction, and the moment the needle valve opens, high-pressure ink is ejected as droplets from the discharge nozzle. The driver is housed in a holder that is elastically expandable in the longitudinal direction. The base end of the holder is fixed to the housing of the inkjet head, and the needle valve is connected to the tip of the holder. Summary of the Invention [Problem to be solved by the invention]

[0004] It is inevitable that the longitudinal dimensions of the driver and the holder will vary to a certain extent. For example, if the driver dimensions are relatively too large, the holder may exert too much pressure on the driver, which may impair the driver's drive efficiency. Conversely, if the driver dimensions are relatively too small, the holder may exert too little pressure on the driver, which may make it difficult to control the extension of the driver.

[0005] An object of the present invention is to provide a driver unit that can apply an appropriate pressure to the driver even if the relative dimensions of the driver and the holder vary.

[0006] An object of the present invention is to provide a driver unit that allows a driver to be easily accommodated in a holder and that can apply a predetermined preload in the longitudinal direction to the driver after it has been accommodated. [Means for solving the problem]

[0007] In order to solve the above problems, the driver unit of the present invention comprises a driver that expands and contracts in a longitudinal direction, and a holder that is expandable and contractable in the longitudinal direction and accommodates the driver in a driver accommodating section, and is characterized in that the holder has a pressing member that is attached to a longitudinal end of the holder and presses the end of the driver. Effect of the Invention

[0008] According to the present invention, even if the relative dimensions of the driver and the holder vary, an appropriate pressure can be applied to the driver. [Brief description of the drawings]

[0009] [Figure 1] 1 is an explanatory diagram showing the appearance of a droplet ejection head according to an embodiment of the present invention; [Diagram 2] 1 is an overall cross-sectional view of a droplet ejection head according to an embodiment of the present invention. [Diagram 3] FIG. 4 is an explanatory diagram showing the position of a heating means of the droplet ejection head. [Figure 4] FIG. 2 is a cross-sectional view of a droplet ejection module. [Figure 5A] FIG. 2 is a side view of the driver unit according to the first embodiment of the present invention. [Figure 5B] FIG. [Figure 5C] 11A to 11C are diagrams illustrating a process of applying a preload to a piezoelectric element. [Figure 6A] FIG. 11 is a side view of a driver unit according to a second embodiment of the present invention. [Figure 6B] FIG. [Figure 6C] 11A to 11C are diagrams illustrating a process of applying a preload to a piezoelectric element. [Figure 7]1 is a schematic diagram illustrating an overall configuration of a droplet ejection device. [Figure 8] FIG. 13 is a side view of a conventional driver unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Droplet ejection head) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram of the appearance of a droplet ejection head according to an embodiment of the present invention. Fig. 1(a) is an overall perspective view of the droplet ejection head, and Fig. 1(b) is an overall side view of the same head.

[0011] The droplet ejection head 300 includes a housing 310a and a housing 310b bonded (laminated) to the housing 310a. The housing 310a is made of a material with high thermal conductivity such as metal, and the housing 310b is made of a material with low thermal conductivity such as resin.

[0012] The housing 310a also includes heaters 340 on its front and rear surfaces. The heaters 340 are temperature controllable and heat the housing 310a. The housing 310b also includes a connector 350 for communication of electrical signals on its upper portion.

[0013] Here, the housing 310a is an example of a first housing, and the housing 310b is an example of a second housing. The heater 340 is an example of a heating means. In the following description, the two housings will be collectively referred to as the housing 310.

[0014] 2 is an overall cross-sectional view (cross-sectional view taken along line AA in FIG. 1(a)) of a droplet ejection head 300 according to an embodiment of the present invention. A housing 310a holds a nozzle plate 301 equipped with nozzles 302 for ejecting droplets. The housing 310a also includes a flow path 312 (liquid supply section) that sends liquid from a supply port 311 side through the nozzle plate 301 to a recovery port 313 side.

[0015] Housing 310b includes a supply port 311 and a recovery port 313 that connect to flow path 312 of housing 310a. Between supply port 311 and recovery port 313, a droplet ejection module 330 is disposed for ejecting the liquid in flow path 312 from nozzle 302 as droplets.

[0016] (Outline of the droplet ejection module) The droplet ejection modules 330 correspond to the number of nozzles 302 provided in the housing 310a, and in this example, a configuration is shown that includes eight droplet ejection modules 330 corresponding to the eight nozzles 302 arranged in a row. Note that the number and arrangement of the nozzles 302 and droplet ejection modules 330 are not limited to those described above.

[0017] For example, the number of nozzles 302 and droplet ejection modules 330 may be one instead of multiple. Furthermore, the nozzles 302 and droplet ejection modules 330 may be arranged in multiple rows instead of one line.

[0018] 2, reference numeral 315 denotes a seal member provided at the joint between housing 310a and housing 310b. In this example, an O-ring is used as the seal member to prevent liquid from leaking from the joint between housing 310a and housing 310b.

[0019] With the above configuration, the supply port 311 takes in pressurized liquid (ink, paint, etc.) from the outside, sends the liquid in the direction of arrow a1, and supplies the liquid to the flow path 312. The flow path 312 sends the liquid from the supply port 311 in the direction of arrow a2. Then, the recovery port 313 recovers the liquid not ejected from the nozzles 302 arranged along the flow path 312 in the direction of arrow a3.

[0020] The droplet ejection module 330 includes a needle valve 331 that opens and closes the nozzle 302, and a piezoelectric element 332 as a driver that drives the needle valve 331. The piezoelectric element 332 expands and contracts in the longitudinal direction when a voltage is applied. The housing 310b includes a regulating member 314 at a position facing the upper end of the piezoelectric element 332. The regulating member 314 abuts against the upper end of the piezoelectric element 332, and forms a fixing point for the piezoelectric element 332.

[0021] Here, the nozzle plate 301 is an example of a plate member, the nozzle 302 is an example of a droplet ejection port, the needle valve 331 is an example of a valve body, and the piezoelectric element 332 is an example of a driver.

[0022] In the above configuration, when the piezoelectric element 332 is operated to move the needle valve 331 upward, the nozzle 302 that was closed by the needle valve 331 opens, and droplets can be ejected from the nozzle 302. When the piezoelectric element 332 is operated to move the needle valve 331 downward, the tip of the needle valve 331 comes into contact with the nozzle 302, closing the nozzle 302 and preventing droplets from being ejected from the nozzle 302.

[0023] 3 is an explanatory diagram showing the positional relationship with the heating means of the droplet ejection head 300 according to the embodiment of the present invention. The housing 310a includes a heater 340 in the vicinity of the nozzles 302 so as to cross the nozzles 302 as shown by the dashed lines in FIG.

[0024] (Details of the droplet ejection module) Next, the details of the droplet ejection module 330 will be described with reference to Fig. 4. Fig. 4(a) is a cross-sectional view of a single droplet ejection module, and Fig. 4(b) is an enlarged view of the main part of Fig. 4(a). On the outer periphery of the shaft of the needle valve 331, O-rings 316 are attached in two stages, upper and lower, to prevent leakage of high-pressure ink.

[0025] The upper end of the housing 310b accommodates a fixing member 361 at the rear end of a driver unit that holds a piezoelectric element 332, which will be described later. The fixing member 361 has a radial through-hole 361a, into which a positioning screw 362 is screwed from outside the housing 310b.

[0026] The positioning screw 362 is inserted into a longitudinally long hole 310b1 formed in the upper end of the housing 310b, and is movable a predetermined distance in the longitudinal direction of the housing 310b in Fig. 4. With the fixing member 361 positioned in the longitudinal direction, the positioning screw 362 is tightened.

[0027] Meanwhile, a female screw hole 310b2 is formed in the upper end opening of the housing 310b. A plug 354 that abuts against the restricting member 314 in Fig. 2 is screwed into this female screw hole 310b2. The plug 354 abuts against the upper end of a fixing member 361 that is positioned in the longitudinal direction by a positioning screw 362, and finally fixes the fixing member 361 in position.

[0028] A compression spring 366 is disposed at the bottom end of the housing 310b. The compression spring 366 biases the driver unit holding the piezoelectric element 332 upward.

[0029] (Thermal expansion of droplet ejection head) Next, thermal expansion of the droplet ejection head 300 will be described. In the droplet ejection head 300, in which the needle valve 331 is moved by the piezoelectric element 332 to open and close the nozzle 302, when the piezoelectric element 332 is continuously driven at a high frequency, heat generated by the piezoelectric element 332 causes thermal expansion in the piezoelectric element 332 and the needle valve 331. As described in the explanation of FIG. 2, the piezoelectric element 332 is fixed to the regulating member 314 at the upper end of the piezoelectric element 332, so that the thermally expanded piezoelectric element 332 extends in the direction of arrow a4 in FIG. 4(a) and pushes the needle valve 331 down toward the nozzle plate 301.

[0030] In addition, the heat from the piezoelectric element 332 is also transmitted to the needle valve 331 in contact with the piezoelectric element 332, and the needle valve 331 itself expands in the direction of arrow a5 due to thermal expansion. As a result, at the contact portion between the tip 331a of the needle valve 331 and the nozzle plate 301, the tip 331a is pressed into the nozzle plate 301.

[0031] Since the amount of displacement of the needle valve 331 by the operation of the piezoelectric element 332 is constant, the greater the amount of depression of the tip 331a of the needle valve 331 into the nozzle plate 301, the more difficult it becomes to open the nozzle 302. For example, in a state in which no thermal expansion occurs, the needle valve 331 moves by a displacement amount G1 due to the operation of the piezoelectric element 332, as shown in Figure 4(b), forming an appropriate gap between the nozzle plate 301 and the tip 331a of the needle valve 331. The liquid in the flow path 312 passes through this gap and can be discharged from the nozzle 302.

[0032] However, in a state where tip 331a of needle valve 331 is bitten into nozzle plate 301 due to thermal expansion, even if needle valve 331 is moved by displacement amount G1, an appropriate gap cannot be obtained between nozzle plate 301 and needle valve 331. The gap between nozzle plate 301 and needle valve 331 becomes narrower than the appropriate value, and the fluid resistance of the liquid increases, so the droplet discharge speed from nozzle 302 also decreases, making it impossible to obtain the desired appropriate discharge amount.

[0033] Furthermore, because the housing 310 is not in contact with the piezoelectric element 332, there is almost no thermal expansion of the housing 310 due to the heat from the piezoelectric element 332. That is, inside the housing 310, the piezoelectric element 332 and the needle valve 331 are stretched due to thermal expansion, while the housing 310 and the nozzle plate 301 are hardly affected by the thermal expansion due to the heat from the piezoelectric element 332. This difference in thermal expansion also leads to a misalignment in the relative positions of the nozzle 302 and the needle valve 331 in the horizontal direction.

[0034] Furthermore, the nozzle plate 301 and the housing 310a may expand or contract depending on the environmental temperature around the head. When the housing 310a expands or contracts, as in the case when the piezoelectric element 332 generates heat, an appropriate gap cannot be obtained between the nozzle plate 301 and the tip 331a of the needle valve 331, and the desired appropriate amount of ejection cannot be obtained.

[0035] As described above, this embodiment is a droplet ejection head 300 having a nozzle plate 301 equipped with a nozzle 302 that ejects droplets, a needle valve 331 that opens and closes the nozzle 302, a piezoelectric element 332 that drives the needle valve 331, and a housing 310 that holds the nozzle plate 301, the needle valve 331, and the piezoelectric element 332. A heater 340 that heats the housing 310 is provided near the nozzle 302 of the housing 310. This makes it possible to provide a droplet ejection head 300 that can reduce droplet ejection variations due to temperature changes.

[0036] The housing 310 is made up of a housing 310a equipped with a heater 340 and a housing 310b not equipped with a heater 340. The piezoelectric element 332 is provided in the housing 310b. This allows heat to be supplied intensively to the vicinity of the nozzle 302, and improves the responsiveness of the position correction of the nozzle 302 relative to the needle valve 331.

[0037] In addition, the housing 310a is made of metal, and the housing 310b is made of resin, which makes it easier to increase the temperature around the nozzle 302, and improves the responsiveness of the position correction of the nozzle 302.

[0038] (First embodiment of the driver unit) Next, a first embodiment of the driving body unit used in the droplet ejection module 330 of FIG. 4 described above will be described with reference to FIGS. 5A to 5C. This driving body unit includes a piezoelectric element 332 as a driving body that expands and contracts in the longitudinal direction, and a holding body 370 that holds the piezoelectric element 332. The holding body 370 has a driving body accommodating portion 370d inside thereof, and the piezoelectric element 332 is accommodated and held in the driving body accommodating portion 370d.

[0039] In this embodiment, the longitudinal dimension L1 of the driving body accommodating portion 370d of the holding body 370 is the same as or slightly longer than the longitudinal dimension L2 of the piezoelectric element 332 (L2 ≤ L1). As shown in FIGS. 5A and 5B, this longitudinal dimension L1 is the inner diameter of the portion that accommodates the piezoelectric element 332.

[0040] In the conventional driving body unit shown in FIG. 8, there is no imoneji 380 (385) as a contact member or an adjustment member to be described later, and due to the press-fitting of the piezoelectric element 332 into the holding body 370, this dimensional relationship is reversed (L1 < L2). This has been a factor that has made it time-consuming to accommodate the piezoelectric element 332.

[0041] The holding body 370 is made of a metal that can elastically expand and contract in the longitudinal direction of the piezoelectric element 332. As the elastically expandable metal, for example, stainless steel such as SUS304 or SUS316L can be used. The holding body 370 is a frame body in which a plurality of elongated members extending in the longitudinal direction are arranged around the piezoelectric element 332 (for example, four are arranged at 90° intervals), and the piezoelectric element 332 can be inserted inside the holding body 370 through the spaces between the elongated members.

[0042] In FIG. 5A, the left side is the tip side of the holding body 370, and a needle valve 331 as a valve body is connected to the tip side. Also in FIG. 5A, the right side is the base end side of the holding body 370, and a fixing member 361 is connected to the base end side. This fixing member 361 is fixed to a regulating member 314 of the housing of the droplet ejection head 300.

[0043] A bellows portion 370a is formed at the tip of each elongated member of holder 370. Bellows portion 370a is for allowing the tip side of holder 370 to expand and contract in the longitudinal direction in the same manner as piezoelectric element 332 when piezoelectric element 332 is expanded and contracted. Bellows portion 370a can be formed at any position in the longitudinal direction of the elongated member of holder 370, but in order to minimize the moving parts, it is preferable to form it at the tip portion close to needle valve 331 as shown in FIG. 5A.

[0044] A set screw 380 serving as a contact member or an adjustment member is screwed into an end wall 370b disposed perpendicular to the longitudinal direction at the tip of the holding body 370. The set screw 380 is configured as a component of the holding body 370, and functions as an adjustment member for adjusting the inner diameter of the driver accommodating portion 370d of the holding body 370.

[0045] That is, the axis of the set screw 380 is aligned with the axis (thrust direction) of the piezoelectric element 332, and the longitudinal dimension L1 of the driver accommodating portion 370d is substantially reduced by tightening the set screw 380. The set screw 380 is screwed into the end wall 370b before the needle valve 331 is connected to the tip of the holder 370. Then, after the piezoelectric element 332 is accommodated in the holder 370, the set screw 380 is tightened.

[0046] 5B and 5C, a set screw 380 is tightened to apply a predetermined preload in the longitudinal direction to the piezoelectric element 332. The piezoelectric element 332 is generally made of a brittle material such as ceramic, and is therefore strong in compression but weak in tension.

[0047] Therefore, a preload is applied in the longitudinal direction to prevent damage due to expansion and contraction of the piezoelectric element 332. Note that while applying a preload to a piezoelectric element is well known, for example as described in Patent Document 2 (bellows member D in FIG. 5), preloading by a screw as in this embodiment has the advantages of a simple configuration and easy adjustment of the magnitude of the preload.

[0048] The method of applying preload is to tighten the set screw 380 so that the tip of the set screw 380 abuts against the end 332a of the piezoelectric element 332, and then further rotate (retighten) the set screw 380 in the tightening direction by a predetermined angle. By retightening the set screw 380 by a predetermined angle, a predetermined preload (compressive stress) can be applied to the piezoelectric element 332 in the longitudinal direction.

[0049] On the other hand, a tensile stress equivalent to the preload (compressive stress) is generated in the holder 370. By applying a preload to the piezoelectric element 332 in this manner, damage to the piezoelectric element 332 is prevented.

[0050] The magnitude of the preload is within a range of 10 to 60%, preferably within a range of 20 to 50%, and most preferably within a range of 30 to 40% of the maximum compressive force in the longitudinal direction generated by the piezoelectric element 332. By applying a preload of such magnitude, the life of the piezoelectric element 332 can be extended.

[0051] After the retightening of the set screw 380 is completed, adhesive R is applied to the head of the set screw 380, and the base end of the needle valve 331 is connected to the tip end of the holder 370. This completes the driver unit.

[0052] If necessary, a flat plate (disk) having the same area as the end face of the piezoelectric element 332 can be interposed at the tip of the set screw 380, or a cap-shaped member that fits onto the end 332a of the piezoelectric element 332 or the tip of the set screw 380 can be attached. These flat plates and cap-shaped members can protect the end of the piezoelectric element 332 from damage caused by vibration.

[0053] (Second embodiment of the driver unit) Next, a second embodiment of the driver unit will be described with reference to Figures 6A to 6C. In this second embodiment, as shown in Figure 6A, the set screw 380 is provided on the opposite side of the piezoelectric element 332.

[0054] 6B, another set screw 385 is screwed into end wall 370c disposed perpendicular to the longitudinal direction of holder 370. This set screw 385 is further tightened to press end portion 332b of piezoelectric element 332, thereby applying a predetermined preload to piezoelectric element 332 in the longitudinal direction.

[0055] The method of rotating the set screw 385 is the same as that of the previously described rotation of the set screw 380. A driver for rotating the set screw 385 can be passed through a through hole 361b formed in the fixing member 361 in the axial direction.

[0056] A through-hole 361a formed in the radial direction of the fixing member 361 is a screw hole into which a positioning screw 362 is screwed, as shown in Fig. 4(a). After the set screw 385 has been retightened, adhesive R is applied to the head of the set screw 385 to prevent it from loosening.

[0057] (Droplet discharge device) Fig. 7 is a schematic diagram of the entire configuration of a droplet ejection device 1000. Fig. 7(a) is a side view of the droplet ejection device, and Fig. 7(b) is a plan view of the same device. The droplet ejection device 1000 is installed facing a drawing target object 100, which is an example of a target object. The droplet ejection device 1000 includes an X-axis rail 101, a Y-axis rail 102 that intersects with the X-axis rail 101, and a Z-axis rail 103 that intersects with the X-axis rail 101 and the Y-axis rail 102.

[0058] The Y-axis rail 102 holds the X-axis rail 101 so that the X-axis rail 101 is movable in the Y-axis direction. The X-axis rail 101 holds the Z-axis rail 103 so that the Z-axis rail 103 is movable in the X-axis direction. The Z-axis rail 103 holds the carriage 1 so that the carriage 1 is movable in the Z-axis direction.

[0059] The droplet ejection device 1000 includes a first Z-direction drive unit 92 that moves the carriage 1 in the Z-axis direction along the Z-axis rail 103, and an X-direction drive unit 72 that moves the Z-axis rail 103 in the X-axis direction along the X-axis rail 101. The droplet ejection device 1000 also includes a Y-direction drive unit 82 that moves the X-axis rail 101 in the Y-axis direction along the Y-axis rail 102. The droplet ejection device 1000 also includes a second Z-direction drive unit 93 that moves the head holder 70 in the Z-axis direction relative to the carriage 1.

[0060] The droplet ejection head 300 described in the first to fourth embodiments is attached to the head holder 70 so that the nozzles 302 of the head 300 face the drawing target 100. The droplet ejection device 1000 configured as described above ejects ink, which is an example of liquid, from the head 300 (not shown) attached to the head holder 70 toward the drawing target 100 while moving the carriage 1 in the X-axis, Y-axis, and Z-axis directions, thereby performing drawing on the drawing target 100.

[0061] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible based on the technical ideas described in the claims. For example, the set screws 380 and 385 as contact members or adjustment members can be replaced with tapered pins. After the piezoelectric element 332 is accommodated in the holder 370, the tapered pin is press-fitted between the longitudinal end of the piezoelectric element 332 and the longitudinal end of the holder 370. By adjusting the insertion amount (press-fit amount) of the tapered pin, the magnitude of the preload can be adjusted in the same way as the set screws 380 and 385.

[0062] Furthermore, the piezoelectric element 332 can be replaced by another driving body that expands and contracts in the longitudinal direction. For example, a piston that expands and contracts in the longitudinal direction using an electromagnetic solenoid can be used instead of the piezoelectric element 332. [Explanation of symbols]

[0063] 1: Carriage 70: Head holder 72: X-direction drive unit 82: Y-direction drive unit 92: First Z-direction drive unit 93: Second Z-direction drive unit 100: Object to be drawn 101: X-axis rail 102: Y-axis rail 103: Z-axis rail 300: Droplet ejection head 301: Nozzle plate (plate member) 302: Nozzle (droplet ejection port) 310: Housing 310a: Housing (first housing) 310b: Housing (second housing) 310b1: Slotted hole 310b2: Female thread hole 311: Supply port 312: Flow path 313: Collection port 314: Regulating member 315: O-ring 316: O-ring 330: Droplet ejection module 331: Needle valve (valve body) 331a: Tip 332: Piezoelectric element (driver) 332a, 332b: Ends 340: Heater (heating means) 350: Connector 354: Plug 361: Fixing member 361a: Through-hole screw hole 361b: Through hole 362: Positioning screw 366: Compression spring 370: Retainer 370a: bellows section 370b: end wall 370c: end wall 370d: driver housing 380, 385: Set screw (contact member, adjustment member) 1000: Droplet ejection device R: Adhesive [Prior art documents] [Patent documents]

[0064] [Patent Document 1] JP 2016-159501 A [Patent Document 2] JP 2008-99399 A (Piezoelectric element A and bellows member D in FIG. 5)

Claims

1. A driving body that expands and contracts in the longitudinal direction; a holder that is extendable in the longitudinal direction and holds the driver in the driver housing, the holder has a contact member attached to a longitudinal end of the holder and contacting an end of the driver, The holder applies pressure to the driver, A driver unit, wherein the contact member is a screw that is screwed into a longitudinal end of the holder.

2. A driving body that expands and contracts in the longitudinal direction; a holder that is extendable in the longitudinal direction and holds the driver in the driver housing, the holder has a contact member attached to a longitudinal end of the holder and contacting an end of the driver, The holder applies pressure to the driver, 4. The driver unit according to claim 1, wherein the contact member is a tapered pin press-fitted between the longitudinal ends of the holder and the driver.

3. A driving body that expands and contracts in the longitudinal direction; a holder that is extendable in the longitudinal direction and holds the driver in the driver housing, The driver unit is characterized in that the holder has an adjustment member attached to a longitudinal end of the holder for adjusting an inner diameter of a driver accommodating portion of the holder.

4. 4. The driver unit according to claim 3, wherein said adjustment member is a screw that is screwed into one of the longitudinal ends of said holder.

5. 4. The driver unit of claim 3, wherein said adjustment member is a tapered pin press-fit between the longitudinal ends of said retainer and said driver.

6. 6. The driving body unit according to claim 1, wherein the driving body is a piezoelectric element.

7. 7. The drive unit according to claim 1, wherein, when a longitudinal dimension of the drive housing portion of the holder is L1 and a longitudinal dimension of the drive body is L2, L2≦L1.

8. A driver unit according to any one of claims 1 to 7; a droplet discharge port for discharging droplets; A droplet ejection head, characterized in that a valve body for opening and closing the droplet ejection port is connected to one end of the holder.

9. The droplet ejection head according to claim 8 ; The droplet ejection device further comprises a liquid supply section for supplying liquid to the droplet ejection port.

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