JPH04276450A - Ink jet head - Google Patents
Ink jet headInfo
- Publication number
- JPH04276450A JPH04276450A JP6274291A JP6274291A JPH04276450A JP H04276450 A JPH04276450 A JP H04276450A JP 6274291 A JP6274291 A JP 6274291A JP 6274291 A JP6274291 A JP 6274291A JP H04276450 A JPH04276450 A JP H04276450A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- pressure chamber
- piezoelectric element
- ink
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000758 substrate Substances 0.000 claims abstract description 21
- 239000011358 absorbing material Substances 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims 1
- 230000000644 propagated effect Effects 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000000945 filler Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000013013 elastic material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001454 recorded image Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Landscapes
- Particle Formation And Scattering Control In Inkjet Printers (AREA)
Abstract
Description
【０００１】0001
【技術分野】本発明は、オンデマンド型のインクジェッ
トヘッドの構造に関し、より詳細には、インク噴射のた
めの圧力室駆動により生ずる駆動部内の圧力反射波を低
減し、複数圧力室（流路）間に生じる相互干渉を抑制す
る構造を有するインクジェットヘッドに関する。TECHNICAL FIELD The present invention relates to the structure of an on-demand inkjet head, and more specifically, the present invention relates to the structure of an on-demand inkjet head, and more specifically, the present invention reduces pressure reflected waves within a drive unit caused by driving pressure chambers for ink ejection. The present invention relates to an inkjet head having a structure that suppresses mutual interference occurring between the inkjet heads.
【０００２】0002
【従来技術】インクジェット記録装置は、極めて低騒音
で高速印字が可能で安価な普通記録紙を用いることがで
きる特徴を備えているが、特に、圧電体を具備してこれ
に電気信号を印加することにより生ずる圧電変位を利用
して圧力室（インク流路）内に圧力波を形成し、必要に
応じたインク滴を吐出するオンデマンド型インクジェッ
ト記録装置は簡易小型な記録装置である。[Prior Art] Inkjet recording devices are characterized by extremely low noise, high-speed printing, and the ability to use inexpensive ordinary recording paper. An on-demand inkjet recording device is a simple and compact recording device that uses piezoelectric displacement caused by this to form pressure waves in a pressure chamber (ink flow path) and ejects ink droplets as needed.
【０００３】図４（ａ），（ｂ），（ｃ）は、インクジ
ェット記録装置のインクジェットヘッドの基本構成を示
す図で、図（ａ）は構成要素を示す斜視図、図（ｂ）は
流路板裏面を示す斜視図、図（ｃ）は構成要素を一体に
接合したときの斜視図である。図中、１１は流路板、１
２は圧電体、１３はインク供給口、１４はオリフィス、
１５は圧力室、１６はインク室、１７は圧電体歪部、１
８は仕切スリット、１８ａは充填剤、１９は基板である
。FIGS. 4(a), 4(b), and 4(c) are diagrams showing the basic configuration of an inkjet head of an inkjet recording apparatus, with FIG. 4(a) being a perspective view showing the components, and FIG. Figure (c) is a perspective view showing the back surface of the road plate, and is a perspective view when the components are joined together. In the figure, 11 is a channel plate, 1
2 is a piezoelectric body, 13 is an ink supply port, 14 is an orifice,
15 is a pressure chamber, 16 is an ink chamber, 17 is a piezoelectric strain section, 1
8 is a partition slit, 18a is a filler, and 19 is a substrate.
【０００４】図示において、流路板１１にはインク供給
口１３よりインクの供給を受けてインクを収容するイン
ク室１６が図（ｂ）に示すごとく裏面に凹部として設け
られており、更に該インク室１６に連通してインクの流
路となり、加圧によりインク滴を吐出するノズル１４を
端部に有する加圧室１５が複数平行して設けられている
。As shown in the figure, an ink chamber 16 for receiving ink from an ink supply port 13 and accommodating the ink is provided as a recess on the back surface of the channel plate 11, as shown in FIG. A plurality of pressurizing chambers 15 are provided in parallel, each of which communicates with the chamber 16 and serves as an ink flow path, and each of which has a nozzle 14 at its end that ejects ink droplets under pressure.
【０００５】圧電体１２は、駆動電圧の印加により厚さ
方向にひずみを生ずる積層された圧電素子からなり、一
面を基板１９上に固着し他面には前記加圧室１５に対向
した位置に加圧室１５の数だけ圧電体歪部１７が設けら
れている。該圧電体歪部１７は、前記加圧室１５より僅
かに狭く加圧室１５の長手方向に延びる凸部をなすもの
で、圧電体１２に平行した複数のスリット１８を設ける
ことにより形成される。なおスリット１８内には低ヤン
グ率の軟質弾性材からなる充填剤１８ａが充填されてい
る。流路板１１と圧電体１２および基板１９は図（ｃ）
に示すごとく圧力室１５と圧電体歪部１７とが対向する
ように重ねられて一体に接合される。The piezoelectric body 12 is composed of laminated piezoelectric elements that generate strain in the thickness direction when a driving voltage is applied. The same number of piezoelectric strain parts 17 as there are pressurizing chambers 15 are provided. The piezoelectric distorted portion 17 is a convex portion that is slightly narrower than the pressure chamber 15 and extends in the longitudinal direction of the pressure chamber 15, and is formed by providing a plurality of parallel slits 18 in the piezoelectric body 12. . Note that the slit 18 is filled with a filler 18a made of a soft elastic material with a low Young's modulus. The flow path plate 11, piezoelectric body 12, and substrate 19 are shown in Figure (c).
As shown in FIG. 2, the pressure chamber 15 and the piezoelectric strain portion 17 are overlapped and joined together so as to face each other.
【０００６】図５（ａ），（ｂ），（ｃ）は、インクジ
ェットヘッドのオリフィス面およびヘッド断面を示す図
で、図（ａ）はオリフィス面の断面図、図（ｂ）は圧力
室断面図、図（ｃ）は図（ａ）のＡＢ線断面図で、図中
、図４と等しい作用をする部分には同一の符号を付して
いる。FIGS. 5(a), 5(b), and 5(c) are views showing the orifice surface and head cross section of the inkjet head. FIG. 5(a) is a sectional view of the orifice surface, and FIG. 5(b) is a cross sectional view of the pressure chamber. FIG. 4C is a cross-sectional view taken along line AB in FIG.
【０００７】図示において、圧電体歪部１７に電圧を印
加すると圧電体歪部１７は厚み方向、すなわち長さＬの
圧力室１６の断面積を小さくする方向に変位するひずみ
が生じ、このひずみにより圧力室１５内に圧力波が生じ
てオリフィス１４よりインク滴を噴射する。しかし、圧
力室１５が複数設けられたインクジェットヘッドの場合
、圧力室１５を単独で駆動した場合と複数同時に駆動し
た場合とではノズル１４よりインク滴を噴射するインク
粒子化特性に違いを生ずる。これは圧力室１５の間に相
互干渉（クロストーク）が生じるためである。相互干渉
が生ずると結果的にドット位置精度を悪化し、ドット径
にバラツキを生じさせ、記録画質を低下させることとな
る。In the figure, when a voltage is applied to the piezoelectric strain section 17, a strain is generated in the piezoelectric strain section 17 that causes the piezoelectric strain section 17 to be displaced in the thickness direction, that is, in a direction that reduces the cross-sectional area of the pressure chamber 16 having a length L. A pressure wave is generated within the pressure chamber 15 and an ink droplet is ejected from the orifice 14. However, in the case of an inkjet head having a plurality of pressure chambers 15, there is a difference in the ink droplet formation characteristics for ejecting ink droplets from the nozzle 14 depending on whether the pressure chambers 15 are driven singly or when a plurality of pressure chambers 15 are driven simultaneously. This is because mutual interference (crosstalk) occurs between the pressure chambers 15. If mutual interference occurs, the dot position accuracy will deteriorate as a result, causing variations in dot diameter, and recording image quality will deteriorate.
【０００８】本出願人が先に提案した特開平１−２４２
２６１号公報の「液体噴射記録ヘッド」は、インク滴を
噴射する際の相互干渉をなくすために複数の圧力室に連
通するインク室に圧力波吸収部材を配設している。圧力
波吸収部材としては、インクを通過するが溶出しにくい
多孔性のポリエチレン等の有機材料、あるいはポーラス
なセラッミクス材料等の無機材料又はステンレス線をメ
ッシュ状に織った金属材料等が用いられている。しかし
、上述の従来技術は圧力波吸収部材をインク室内に配設
しているので、インク室を介して非駆動の圧力室に伝わ
る圧力波を原因とする相互干渉については有効であるが
、固体部品を介する振動や共振現象等に対しては効果は
なく、相互干渉の低減対策としては必ずしも十分なもの
とは云えなかった。[0008] Unexamined Japanese Patent Publication No. 1-242, which was previously proposed by the present applicant.
In the "liquid jet recording head" disclosed in Japanese Patent No. 261, a pressure wave absorbing member is provided in an ink chamber communicating with a plurality of pressure chambers in order to eliminate mutual interference when jetting ink droplets. As the pressure wave absorbing member, organic materials such as porous polyethylene that pass through ink but are difficult to dissolve, inorganic materials such as porous ceramic materials, or metal materials such as stainless steel wire woven into a mesh are used. . However, since the above-mentioned conventional technology disposes a pressure wave absorbing member in the ink chamber, it is effective against mutual interference caused by pressure waves transmitted to a non-driven pressure chamber via the ink chamber, but It has no effect on vibrations or resonance phenomena occurring through parts, and cannot necessarily be said to be a sufficient measure to reduce mutual interference.
【０００９】[0009]
【目的】本発明は、上述のごとき実情に鑑みてなされた
もので、加圧室内にインク噴射圧力を発生させる圧力波
発生手段において、該圧力波発生手段を駆動したとき圧
力波発生手段内を伝播し反射する圧力波を低減すること
により効率よく雑音成分となる圧力波を減衰し、これに
より複数の加圧室間の相互干渉を改善して高画質のイン
クジェットヘッドを提供することを目的とするものであ
る。[Object] The present invention has been made in view of the above-mentioned circumstances, and includes a pressure wave generating means for generating ink ejection pressure in a pressurizing chamber. The objective is to efficiently attenuate pressure waves that become noise components by reducing the pressure waves that propagate and reflect, thereby improving mutual interference between multiple pressurizing chambers and providing an inkjet head with high image quality. It is something to do.
【００１０】0010
【構成】本発明は、上記目的を達成するために、（１）
インクを噴射するオリフィスと、前記オリフィスに連通
しインク噴射圧力を発生する圧力室と、該圧力室に連通
し該圧力室よりも音響的に十分大きな容積を有し、前記
圧力室にインクを供給するインク室と、前記圧力室の容
積に変化を与えインク噴射圧力を付与する圧電素子とか
らなり、前記オリフィスと圧力室とからなるインク噴射
流路を複数個１次元的に配設したインクジェットヘッド
において、前記圧電素子の圧力室側面と反対な面に該圧
電素子を固着する基板を設け、該基板の固有音響インピ
ーダンスを前記圧電素子の固有音響インピーダンスに対
し０．８〜１．２５倍の範囲に設定したこと、更には、
（２）前記（１）において、前記圧電素子と前記基板と
の接合部に吸音材を設け、該吸音材を金属等を混合した
ゴムとしたこと、更には、（３）前記（１）又は（２）
において、前記圧電素子の駆動により発生する圧力室内
のインク噴射圧力に代えて、前記圧力室の一部に電気熱
変換手段を設け、該電気熱変換手段に電気的パルスを印
加して加熱することにより、加熱部分の液体・気体の相
変化に基づく圧力波としたことを特徴としたもので、以
下、本発明の実施例に基づいて説明する。[Structure] In order to achieve the above objects, the present invention provides (1)
an orifice that ejects ink; a pressure chamber that communicates with the orifice and generates ink ejection pressure; and an orifice that communicates with the pressure chamber and has a volume that is acoustically sufficiently larger than that of the pressure chamber, and supplies ink to the pressure chamber. an ink chamber, and a piezoelectric element that changes the volume of the pressure chamber and applies ink ejection pressure, and has a plurality of ink ejection channels each consisting of the orifice and the pressure chamber arranged one-dimensionally. A substrate for fixing the piezoelectric element is provided on a surface of the piezoelectric element opposite to a side surface of the pressure chamber, and the specific acoustic impedance of the substrate is in a range of 0.8 to 1.25 times the specific acoustic impedance of the piezoelectric element. In addition,
(2) In (1) above, a sound absorbing material is provided at the joint between the piezoelectric element and the substrate, and the sound absorbing material is made of rubber mixed with metal etc.; (2)
In this method, instead of the ink ejection pressure within the pressure chamber generated by driving the piezoelectric element, an electrothermal conversion means is provided in a part of the pressure chamber, and an electric pulse is applied to the electrothermal conversion means to heat it. This is characterized by a pressure wave based on the phase change of liquid/gas in the heated portion, and will be described below based on embodiments of the present invention.
【００１１】前記において、相互干渉が生じると印字の
ドット位置精度が悪化し、ドット径にバラツキを生じさ
せ記録画質を低下させるが、この原因として圧力室を単
独駆動した場合と複数駆動した場合とにおけるインク粒
子化特性の相違が生じるためであり、この原因として圧
力室内に生ずる圧力波があることを述べた。しかし、相
互干渉の原因には、上述の圧力室内を伝播する圧力波に
よる以外に圧力室を駆動する圧電素子の厚み方向の振動
の影響がある。[0011] In the above, when mutual interference occurs, the accuracy of printing dot positions deteriorates, causing variations in dot diameter and deteriorating the recorded image quality, but this is caused by the fact that the pressure chambers are driven singly and when multiple pressure chambers are driven. This is due to the difference in the ink particle formation characteristics between the two, and it has been stated that the cause of this is the pressure waves generated within the pressure chamber. However, the mutual interference is caused not only by the pressure waves propagating within the pressure chamber but also by vibrations in the thickness direction of the piezoelectric element that drives the pressure chamber.
【００１２】図１は、本発明のインクジェットヘッドの
原理を説明するためのノズル側からみた断面構成図で、
図中、１は流路板、２は圧電素子、２ａは下端面、３は
圧力室、４は圧電素子歪部、４ａは上端面、５はスリッ
ト、５ａは充填剤、６は基板である。図示のインクジェ
ットヘッドは、図４に示したインクジェットヘッドと同
一構造のもので流路板１に設けられた複数の加圧室３と
対向して圧電素子歪部４が設けられている。該圧電素子
歪部４は、基板６上に接合し厚み方向に分極された圧電
素子２にスリット５を設けることにより形成され、スリ
ット５には軟質弾性剤等の充填剤５ａが充填されている
。まず、上述のインクジェットヘッドの圧電素子２の厚
み方向の振動による相互干渉の発生のメカニズムを説明
する。FIG. 1 is a cross-sectional configuration diagram seen from the nozzle side for explaining the principle of the inkjet head of the present invention.
In the figure, 1 is a channel plate, 2 is a piezoelectric element, 2a is a lower end surface, 3 is a pressure chamber, 4 is a strained part of the piezoelectric element, 4a is an upper end surface, 5 is a slit, 5a is a filler, and 6 is a substrate. . The illustrated inkjet head has the same structure as the inkjet head shown in FIG. 4, and is provided with a piezoelectric element distortion portion 4 facing a plurality of pressurizing chambers 3 provided in a channel plate 1. The piezoelectric element strain portion 4 is formed by providing a slit 5 in the piezoelectric element 2 which is bonded onto a substrate 6 and polarized in the thickness direction, and the slit 5 is filled with a filler 5a such as a soft elastic agent. . First, the mechanism of occurrence of mutual interference due to vibration in the thickness direction of the piezoelectric element 2 of the above-mentioned inkjet head will be explained.
【００１３】インク滴の噴射は、圧電素子歪部４に、該
圧電素子歪部４の厚み方向に電圧を印加し、厚み方向、
すなわち図示矢印Ｄ方向のひずみを発生させこのひずみ
により圧力室３内に圧力波を発生させることによる。こ
のとき、圧電素子歪部４のひずみによって生じた圧力波
は、圧電素子歪部４上端面４ａにおいて圧力室３内のイ
ンク側に透過すると同時に反射する。他方圧電素子歪部
４のひずみによって生じた圧力波の一部は圧電素子下部
面２ａにも伝播し、下端面２ａにて反射および透過する
。これら圧電素子歪部４の上端面４ａと下端面２ａとで
反射する圧力波は定在波となり、圧電素子２を厚み方向
に振動させる。この振動は、隣接する圧力室３にも伝播
して相互干渉の一要因となる。Ink droplets are ejected by applying a voltage to the piezoelectric strained portion 4 in the thickness direction of the piezoelectric strained portion 4.
In other words, a strain is generated in the direction of arrow D in the figure, and this strain generates a pressure wave within the pressure chamber 3. At this time, the pressure wave generated by the strain in the piezoelectric strain section 4 is transmitted to the ink side in the pressure chamber 3 at the upper end surface 4a of the piezoelectric strain section 4, and is simultaneously reflected. On the other hand, a part of the pressure wave generated by the strain in the piezoelectric element strain section 4 also propagates to the lower surface 2a of the piezoelectric element, and is reflected and transmitted at the lower end surface 2a. The pressure waves reflected by the upper end surface 4a and the lower end surface 2a of the piezoelectric element strain portion 4 become standing waves, causing the piezoelectric element 2 to vibrate in the thickness direction. This vibration also propagates to the adjacent pressure chambers 3 and becomes a factor of mutual interference.
【００１４】本発明は、上述の圧電素子２の下端面にお
ける圧力波の反射を低減し、これによって相互干渉によ
る振動を低減するものであり、その原理を以下に述べる
。まず、圧電素子の下端面２ａでの振幅反射率：Ｒｐ
圧電素子の下端面２ａでのエネルギ反射率：ＲＩ
とすると、The present invention reduces the reflection of pressure waves at the lower end surface of the piezoelectric element 2, thereby reducing vibrations due to mutual interference.The principle thereof will be described below. First, the amplitude reflectance at the lower end surface 2a of the piezoelectric element: Rp
Energy reflectance at the lower end surface 2a of the piezoelectric element: RI
Then,
【００１５】[0015]
【数１】[Math 1]
【００１６】
ここで、ρ１ｃ１：圧電素子の固有音響インピーダンス
ρ２ｃ２：基板の固有音響インピーダンス以上の関係か
ら、圧電素子２と基板６との固有音響インピーダンスρ
ｃ（密度×音速）を近づけると振幅反射率Ｒｐを低減で
き、エネルギ反射率ＲＩも低減される。すなわち反射波
を低減できることがわかる。Here, ρ1c1: Specific acoustic impedance of the piezoelectric element ρ2c2: Specific acoustic impedance of the substrate From the above relationship, the specific acoustic impedance ρ of the piezoelectric element 2 and the substrate 6
When c (density×sound velocity) is brought closer, the amplitude reflectance Rp can be reduced, and the energy reflectance RI is also reduced. In other words, it can be seen that reflected waves can be reduced.
【００１７】本発明では、基板の固有音響インピーダン
スρ２ｃ２として、圧電素子の固有音響インピーダンス
ρ１ｃ１との間の好適な範囲として以下の範囲を設定す
る。
０．８ρ１ｃ１≦ρ２ｃ２≦１．２５ρ１ｃ１この時、
振幅反射率｜Ｒｐ｜≦０．１１２エネルギ反射率ＲＩ≦
０．０１２
となる。圧電素子として、ＰＺＴ等の圧電セラミックス
を用いた場合、圧電素子の固有音響インピーダンスρ１
ｃ１が２２〜３０×１０−５（ｃｇｓ）となる。そのた
め基板６として、固有音響インピーダンスρ２ｃ２をみ
るとスズ（２４．６×１０−５）、チタニウム（２７．
４×１０−５）、鉛（２２．４×１０−５）、ベリリウ
ム（２４．１×１０−５）等であり、これらの材料が基
板として適当である。In the present invention, the following range is set as a preferable range between the intrinsic acoustic impedance ρ2c2 of the substrate and the intrinsic acoustic impedance ρ1c1 of the piezoelectric element. 0.8ρ1c1≦ρ2c2≦1.25ρ1c1 At this time,
Amplitude reflectance｜Rp｜≦0.112 Energy reflectance RI≦
It becomes 0.012. When piezoelectric ceramics such as PZT are used as the piezoelectric element, the specific acoustic impedance ρ1 of the piezoelectric element
c1 becomes 22 to 30×10 −5 (cgs). Therefore, the specific acoustic impedance ρ2c2 of the substrate 6 is tin (24.6 x 10-5), titanium (27.
4×10 −5 ), lead (22.4×10 −5 ), beryllium (24.1×10 −5 ), etc., and these materials are suitable for the substrate.
【００１８】図２は、本発明のインクジェットヘッドの
他の実施例を説明するためのノズルからみた断面図で、
図中、７は吸音材で、図１と等しい作用をする部分には
同一の符号を付している。図示において吸音材７は、圧
電素子２と基板６との接合面に介在して積層構造時に接
合されたもので、固有音響インピーダンスρｃ（密度×
音速）を圧電素子２の固有音響インピーダンスρ１ｃ１
に近い値に設定したものである。FIG. 2 is a sectional view of another embodiment of the inkjet head of the present invention as seen from the nozzle.
In the figure, 7 is a sound absorbing material, and parts having the same function as in FIG. 1 are given the same reference numerals. In the figure, the sound absorbing material 7 is interposed between the bonding surface of the piezoelectric element 2 and the substrate 6 and is bonded during the laminated structure, and has a specific acoustic impedance ρc (density x
velocity of sound) is the characteristic acoustic impedance ρ1c1 of the piezoelectric element 2
It is set to a value close to .
【００１９】上述のように吸音材１０の固有音響インピ
ーダンスρｃを圧電素子の固有音響インピーダンスρ１
ｃ１に近づけると、数１の（１），（２）式から明らか
なように振幅反射率（Ｒｐ）、エネルギ反射率（ＲＩ）
を共に減少させることとなり、圧電素子２内を伝播する
圧力波による相互干渉を抑制することができる。なお、
吸音材７としては、ゴムを母材として密度の高い鉛、タ
ングステン等の粉末を混合することにより密度ρをあげ
ることにより、吸音材７の固有音響インピーダンスρｃ
を圧電素子２の固有音響インピーダンスに近づける。一
般的にゴム材の圧力波の内部減衰率は高いので（吸音材
として働く）、一度透過した圧力波は、雑音とはならず
相互干渉もおこらない。As mentioned above, the characteristic acoustic impedance ρc of the sound absorbing material 10 is expressed as the characteristic acoustic impedance ρ1 of the piezoelectric element.
As it approaches c1, the amplitude reflectance (Rp) and energy reflectance (RI) are
As a result, mutual interference caused by pressure waves propagating within the piezoelectric element 2 can be suppressed. In addition,
For the sound absorbing material 7, the specific acoustic impedance ρc of the sound absorbing material 7 can be increased by increasing the density ρ by mixing high-density powder such as lead or tungsten with rubber as a base material.
is made close to the specific acoustic impedance of the piezoelectric element 2. Rubber materials generally have a high internal attenuation rate for pressure waves (acting as a sound absorbing material), so once the pressure waves have passed through, they do not become noise and do not cause mutual interference.
【００２０】図３は、本発明の更に他のインクジェット
ヘッドの実施例を説明するためのノズルからみた断面図
で、図中、８は電気熱変換手段、９は素子板であり、図
２と等しい作用をする部分には同一の符号を付している
。FIG. 3 is a sectional view seen from the nozzle for explaining still another embodiment of the ink jet head of the present invention. In the figure, 8 is an electrothermal conversion means, 9 is an element plate, Parts that have the same effect are given the same reference numerals.
【００２１】図示のインクジェットヘッドは圧力室３内
の一部に電気熱変換手段８を設けたもので、該電気熱変
換手段８は素子板９上に固着され、電圧パルスの印加に
よって発熱し、圧力室３内のインクを瞬間的に気化し、
該液体・気体の相変化に基づく圧力波によりインク滴を
噴射するバブルインクジェット方式のものである。この
場合も前記圧力波は素子板９を伝播し、該素子板９との
境界面において透過、反射を引きおこすが、素子板９と
吸音材７との固有音響インピーダンスを近似してあるの
で、透過した圧力波は吸音材７であるゴム材内において
減衰し、前記同様に圧力波の相互干渉は低減される。The illustrated inkjet head is provided with an electrothermal conversion means 8 in a part of the pressure chamber 3. The electrothermal conversion means 8 is fixed on an element plate 9 and generates heat by applying a voltage pulse. Instantly vaporizes the ink in the pressure chamber 3,
This is a bubble ink jet method in which ink droplets are ejected by pressure waves based on the phase change of the liquid/gas. In this case as well, the pressure wave propagates through the element plate 9 and causes transmission and reflection at the interface with the element plate 9, but since the characteristic acoustic impedance between the element plate 9 and the sound absorbing material 7 is approximated, the pressure wave is transmitted through the element plate 9. The generated pressure waves are attenuated within the rubber material that is the sound absorbing material 7, and the mutual interference of the pressure waves is reduced in the same manner as described above.
【００２２】[0022]
【効果】以上の説明から明らかなように、本発明による
と、以下のような効果がある。
（１）請求項１に対応する効果：圧電素子と圧電素子取
付基板との固有音響インピーダンスを同程度に設定して
いるので、圧電素子の厚み方向の振動が低減し、この結
果、圧力波の相互干渉が改善し、印字画質を向上する。
（２）請求項２，３に対応する効果：圧力発生手段と基
板との間の固有音響インピーダンスを高めたゴム材を介
在させて固着しているので効率よく雑音圧力波を減衰す
ることができる。この結果、圧力波は相互干渉が改善し
、印字画質を向上する。[Effects] As is clear from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: Since the specific acoustic impedance of the piezoelectric element and the piezoelectric element mounting board are set to the same level, vibration in the thickness direction of the piezoelectric element is reduced, and as a result, pressure waves are reduced. Mutual interference is improved and print image quality is improved. (2) Effects corresponding to claims 2 and 3: Since the pressure generating means and the substrate are fixed with a rubber material with high specific acoustic impedance interposed therebetween, noise pressure waves can be efficiently attenuated. . As a result, mutual interference between pressure waves is improved, and print image quality is improved.
【図１】 本発明のインクジェットヘッドの原理を説
明するためのノズル側からみた断面構成図である。FIG. 1 is a cross-sectional configuration diagram seen from the nozzle side for explaining the principle of an inkjet head of the present invention.
【図２】 本発明のインクジェットヘッドの他の実施
例を説明するためのノズルからみた断面図である。FIG. 2 is a sectional view seen from a nozzle for explaining another embodiment of the inkjet head of the present invention.
【図３】 本発明のインクジェットヘッドの更に他の
実施例を説明するためのノズルからみた断面図である。FIG. 3 is a sectional view seen from the nozzle for explaining still another embodiment of the inkjet head of the present invention.
【図４】 インクジェット記録装置のインクジェット
ヘッドの基本構成を示す図である。FIG. 4 is a diagram showing the basic configuration of an inkjet head of an inkjet recording apparatus.
【図５】 インクジェットヘッドのオリフィス面およ
びヘッド断面を示す図である。FIG. 5 is a diagram showing an orifice surface of an inkjet head and a cross section of the head.
１…流路板、２…圧電素子、２ａ…下端面、３…圧力室
、４…圧電素子歪部、４ａ…上端面、５…スリット、５
ａ…充填剤、６…基板、８…電気熱変換手段、９…素子
板。DESCRIPTION OF SYMBOLS 1... Channel plate, 2... Piezoelectric element, 2a... Lower end surface, 3... Pressure chamber, 4... Piezoelectric element distortion part, 4a... Upper end surface, 5... Slit, 5
a... Filler, 6... Substrate, 8... Electrothermal conversion means, 9... Element plate.
Claims (3)
オリフィスに連通しインク噴射圧力を発生する圧力室と
、該圧力室に連通し該圧力室よりも音響的に十分大きな
容積を有し、前記圧力室にインクを供給するインク室と
、前記圧力室の容積に変化を与えインク噴射圧力を付与
する圧電素子とからなり、前記オリフィスと圧力室とか
らなるインク噴射流路を複数個１次元的に配設したイン
クジェットヘッドにおいて、前記圧電素子の圧力室側面
と反対な面に該圧電素子を固着する基板を設け、該基板
の固有音響インピーダンスを前記圧電素子の固有音響イ
ンピーダンスに対し０．８〜１．２５倍の範囲に設定し
たことを特徴とするインクジェットヘッド。1. An orifice for ejecting ink, a pressure chamber that communicates with the orifice and generates ink ejection pressure, and a pressure chamber that communicates with the pressure chamber and has a volume that is acoustically sufficiently larger than that of the pressure chamber; It consists of an ink chamber that supplies ink to the chamber, and a piezoelectric element that changes the volume of the pressure chamber and applies ink ejection pressure, and one-dimensionally connects a plurality of ink ejection channels each consisting of the orifice and the pressure chamber. In the disposed inkjet head, a substrate to which the piezoelectric element is fixed is provided on the opposite side of the pressure chamber side of the piezoelectric element, and the specific acoustic impedance of the substrate is 0.8 to 1 with respect to the specific acoustic impedance of the piezoelectric element. An inkjet head characterized by being set to a range of .25 times.
に吸音材を設け、該吸音材を金属等を混合したゴムとし
たことを特徴とする請求項１記載のインクジェットヘッ
ド。2. The inkjet head according to claim 1, wherein a sound absorbing material is provided at a joint between the piezoelectric element and the substrate, and the sound absorbing material is made of rubber mixed with metal or the like.
力室内のインク噴射圧力に代えて、前記圧力室の一部に
電気熱変換手段を設け、該電気熱変換手段に電気的パル
スを印加して加熱することにより、加熱部分の液体・気
体の相変化に基づく圧力波としたことを特徴とする請求
項１又は２記載のインクジェットヘッド。3. In place of the ink ejection pressure within the pressure chamber generated by driving the piezoelectric element, an electrothermal conversion means is provided in a part of the pressure chamber, and an electric pulse is applied to the electrothermal conversion means. 3. The inkjet head according to claim 1, wherein the heating generates a pressure wave based on a phase change of liquid/gas in the heated portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6274291A JPH04276450A (en) | 1991-03-04 | 1991-03-04 | Ink jet head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6274291A JPH04276450A (en) | 1991-03-04 | 1991-03-04 | Ink jet head |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04276450A true JPH04276450A (en) | 1992-10-01 |
Family
ID=13209153
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6274291A Pending JPH04276450A (en) | 1991-03-04 | 1991-03-04 | Ink jet head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04276450A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6036301A (en) * | 1997-03-13 | 2000-03-14 | Kabushiki Kaisha Toshiba | Ink jet recording apparatus |
-
1991
- 1991-03-04 JP JP6274291A patent/JPH04276450A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6036301A (en) * | 1997-03-13 | 2000-03-14 | Kabushiki Kaisha Toshiba | Ink jet recording apparatus |
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