JP2008126569A - Inkjet type droplet discharge apparatus and recorder with apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that using ink containing settleable fine particles in a conventional recording head causes the fine particles to be settled out and attached to the head inside and the vicinity of a nozzle opening, ink droplet discharge characteristics to change, and an ink flying direction to shift, and that a coated film quality and recording quality are deteriorated owing to these causes. <P>SOLUTION: The inkjet type droplet discharge apparatus is provided with: a means for forming a liquid layer containing fine particles in front of a nozzle opening; and a means for supplying a liquid not containing the fine particles to the inside of a pressurizing chamber 140 via an introduction throttling part 145, for pressurizing the liquid in the pressurizing chamber 140 and making the pressure act on the liquid layer 230 which the fine particles enter from the nozzle opening, and for discharging ink droplets containing the fine particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet droplet discharge apparatus capable of recording a high-quality image with high reliability even when ink containing sedimentation fine particles is used, and a recording apparatus equipped with these.

  The ink jet system is a system in which various liquids are ejected as droplets from a nozzle opening and directly landed on a recording medium. Therefore, recording on products such as plastic and metal is possible without being limited to printers that record information on recording paper. The liquid is not limited to ordinary ink in which a dye or pigment is dissolved and dispersed in a solvent or dispersion, but a solution in which fine particles of plastic, metal, or the like are dispersed can also be used. Due to such characteristics, application to a marking device for products, a high-precision high-speed coating film device for a predetermined location, and the like is being promoted in the industrial field.

  There are various ink jet methods depending on the droplet ejection method and the droplet flight trajectory control method, but a small number of inks can be used without waste, and a multi-nozzle on-demand type ink jet capable of accumulating many nozzles. The method is also attracting attention in industrial applications.

  There are various types of on-demand ink jet heads. The push-type piezoelectric element type on-demand ink jet head includes a pressure chamber having a nozzle opening and an ink introduction throttle portion, and guides ink from the introduction throttle portion into the pressure chamber. The volume is reduced, and ink droplets are ejected from the nozzle openings (see, for example, Patent Document 1).

  Further, unlike the head, there is no introduction throttle part to the pressurizing chamber, liquid is supplied to the front face of the nozzle opening from another path to form an ink layer, and ink is filled from the nozzle opening into the pressurizing chamber. . A head having a structure in which the volume of the pressurizing chamber is reduced by driving the piezoelectric element, pressure is applied to the ink layer from the nozzle opening, and ink droplets are ejected along with ink in the ink layer is disclosed (for example, , See Patent Document 2).

JP-A-6-270403 Japanese Examined Patent Publication No. 3-58918

  However, when a liquid containing sedimentary fine particles is used in such a conventional ink jet type droplet discharge device, the fine particles settle and adhere to the introduction throttle portion, the pressure chamber, and the vicinity of the nozzle opening. Is seen.

  Such settling and adhesion affects the droplet ejection characteristics of the nozzle, and changes the velocity and volume of the droplet. Further, the adhesion and aggregation of fine particles in the vicinity of the nozzle opening may shift the flying direction of the droplets, and there is a problem that the recording quality and the coating film quality may be deteriorated due to these causes.

  SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described conventional problems and to provide an ink jet type droplet discharge apparatus capable of recording a high-quality image or coating film with high reliability, and an ink jet recording apparatus equipped with these. .

  According to a first aspect of the present invention for solving the above-mentioned problem, the first liquid not containing fine particles is supplied into the pressurizing chamber through the introduction restricting portion, and is pressurized in the pressurizing chamber. Means for applying pressure to the liquid layer of the second liquid containing fine particles from the opening to discharge the second liquid as droplets; and a liquid layer of the second liquid containing fine particles on the front surface of the nozzle opening. And means for forming.

  According to a second aspect of the present invention for solving the above-mentioned problems, in the ink jet type droplet discharge apparatus according to the first aspect, the means for forming the liquid layer of the second liquid has a predetermined relationship with the nozzle opening. An ink layer forming plate disposed with a gap and having a liquid layer forming opening at a position opposite to the nozzle opening, and a liquid supply means for supplying a second liquid to the gap are provided.

  According to a third aspect of the present invention for solving the above-mentioned problems, in the ink jet type liquid droplet ejection apparatus according to the first or second aspect, the means for ejecting the second liquid as a liquid droplet includes the nozzle opening. An orifice plate provided, a pressure chamber communicating with the nozzle opening and having one surface made of a flexible member, an introduction throttle portion for guiding the first liquid to the pressurization chamber, and the introduction throttle portion A piezoelectric element unit comprising a common liquid chamber for supplying a first liquid, a piezoelectric element that comes into contact with the flexible member, a fixed substrate that holds the piezoelectric element, and an electrode that energizes the piezoelectric element. It is characterized by.

  A fourth aspect of the present invention for solving the above-mentioned problems is a recording apparatus comprising the ink jet liquid droplet ejection apparatus according to any one of the first to third aspects. To do.

  According to the present invention, since the sedimentation fine particles do not enter the introduction throttle portion or the pressurizing chamber, the droplet discharge characteristics do not easily change due to the sedimentation of the fine particles. In addition, the front surface of the nozzle opening is covered with a liquid layer and is always wet, so that adhesion and aggregation of fine particles near the nozzle opening can be prevented, and the liquid layer formation opening can be set larger than the nozzle opening. Since there is little influence on the droplet discharge by the fine particle aggregate, the deviation of the flying direction of the droplet hardly occurs. Therefore, it is always possible to stably discharge droplets, and it is possible to provide an ink jet type droplet discharge apparatus capable of recording high-quality images and coating film formation with high reliability.

  Hereinafter, an example of the present invention will be described with reference to the drawings.

  FIG. 1 is a view for explaining the configuration and operation of an ink jet type droplet discharge apparatus as an example of the present invention, and FIG. 2 is an enlarged partial perspective view for explaining the structure and operation of a head portion.

  The ink jet type droplet discharge device according to the present invention includes a head unit 10, a second liquid supply device 50 that supplies a second liquid containing sedimentation fine particles, and a first liquid that does not contain sedimentation fine particles. A first liquid supply device 60 for supplying a liquid is provided. The head unit 10 includes a droplet discharge main body unit 100 and a liquid layer forming liquid supply unit 200.

  First, the configuration and operation of the droplet discharge main body 100 that discharges the first liquid will be described.

  The droplet discharge main body 100 includes a first flow path unit 101 serving as a flow path for a first liquid, a head housing (not shown) that holds the first flow path unit 101, and a piezoelectric element unit 103. . Among these, the flow path unit 101 has an orifice plate 130 provided with a plurality of nozzle openings 131, a flow path forming plate 142 that forms a flow path, and an elastically deformable diaphragm forming plate 122 attached in this order. Become. On the other hand, in the piezoelectric element unit 103, a plurality of piezoelectric elements 110 obtained by dividing a bar-shaped piezoelectric element into comb teeth are fixed to a piezoelectric element support substrate 113. Then, when the piezoelectric element 110 comes into contact with the diaphragm forming plate 122, n nozzles are configured in the head unit 10.

  More specifically, as shown in FIG. 2, each nozzle has n nozzle openings 131 arranged on the orifice plate 130 in rows at a predetermined pitch. The pressure chamber 140 includes a nozzle opening 131 as an opening end, an introduction throttle unit 145 that guides liquid to the pressurization chamber 140, and a common liquid chamber 150 that supplies liquid to the introduction throttle unit 145. Further, by attaching the diaphragm forming plate 122, at least one wall surface of the pressurizing chamber 140 is formed by the diaphragm 120. One end of the piezoelectric element 110 of the piezoelectric element unit 103 is attached to the surface of the diaphragm 120 opposite to the pressurizing chamber 140. That is, the tip of the piezoelectric element 110 is abutted against the diaphragm 120 and attached to the diaphragm via an adhesive layer (not shown). Each nozzle has the same structure.

  The piezoelectric element 110 of each nozzle element is attached to the piezoelectric element support substrate 113 by bonding or the like to constitute the piezoelectric element unit 103. The piezoelectric element support substrate 113 is fixed to the head housing.

  The piezoelectric element 110 has a laminated structure as shown in FIG. 2, and a plurality of layered piezoelectric elements 111 are laminated via layered electrodes 112. Then, every other layered electrode 112 is connected to a common electrode 1121 and individual electrodes 1122 formed on the side surface of the piezoelectric element. The common electrode 1121 and the individual electrode 1122 are connected to the common electrode 1121 and the individual electrode 1122 formed on the upper surface of the piezoelectric element support base 113, and further connected to the flexible cable terminal 161 of the flexible cable 160. Each layered piezoelectric element 111 of the rod-shaped piezoelectric element 110 has remanent polarization 1123.

  Next, the configuration and operation of the liquid layer forming liquid supply unit 200 for forming the second liquid layer will be described.

  On the orifice plate 130 in which the nozzle openings 131 are formed, the liquid layer forming plate 210 is disposed while maintaining a predetermined gap from the orifice plate 130. This predetermined gap is secured by sandwiching the flow path forming plate 220 between the orifice plate and the liquid layer forming plate 210. The liquid layer forming plate 210 has a liquid layer forming opening 211 formed in front of the nozzle opening 131. For example, the gap G is set to 100 μm, the nozzle opening 131 is set to a diameter of 35 μm, and the liquid layer forming opening 211 is set to a diameter of about 150 μm.

  In addition, the orifice plate 130 and the liquid layer forming plate 210 are in a facing position. A gap between the orifice plate 130 and the liquid layer forming plate 210 is formed by interposing a liquid supply path forming plate 220, and this gap forms a second liquid supply flow path 221, and the second flow path through the inflow path 222. It is connected to the liquid supply device 50. The supply channel 221 is connected to a recovery unit 55 that recovers the second liquid via the recovery channel 223.

  The liquid supplied from the second liquid supply device 50 by the liquid layer forming liquid supply unit 200 having the above-described structure passes through the inflow path 222, passes through the supply flow path 221, and accumulates in the liquid layer forming opening 211, A liquid layer 230 can be formed on the front surface of the opening 131. Since the supply channel 221 is connected to the recovery unit 55 via the recovery channel 223, there is a second liquid flow in the supply channel 221, and the second liquid in the supply channel 221 and the like. Precipitation of fine particles and the like contained in is prevented. Moreover, the static pressure in the supply flow path 221 is maintained at a negative pressure from the external pressure, and the liquid layer 230 is appropriately formed.

  On the other hand, the first liquid supplied from the first liquid supply device 60 is filled with the first liquid up to the pressurizing chamber 140 and the nozzle opening 131 through the inflow passage 147, the introduction throttle portion 145, and the like. The static pressure in the pressurizing chamber 140 is kept slightly positive with respect to the static pressure in the second liquid supply channel 221, so that the second liquid enters the pressurizing chamber 140 from the nozzle opening 131. It is also possible to prevent this.

  When an ejection driving pulse is applied to the common electrode 1121 of the piezoelectric element 110 and the individual electrode 1122 of the nozzle to be ejected is grounded by a switching element (not shown), the ejection driving pulse is applied to the piezoelectric element. As a result, the diaphragm 120 is deformed toward the pressurizing chamber 140 and the volume of the pressurizing chamber 140 is reduced. As a result, the first liquid is ejected as droplets from the nozzle openings 131, and the ejection pressure acts on the second liquid layer 230. Accordingly, the droplet 20 containing the first and second liquids is ejected along with the second liquid in the liquid layer 230.

  According to such a droplet discharge device according to the present invention, since the sedimentation fine particles do not enter the introduction restricting portion 145 and the pressurizing chamber 140, the liquid discharge characteristics fluctuate due to the sedimentation of the fine particles. Hateful. Further, the front surface of the nozzle opening 131 is covered with the liquid layer 230 and is always wet, and adhesion and aggregation of fine particles in the vicinity of the nozzle opening 131 can be prevented. In addition, since the liquid layer forming opening 211 is set to be considerably larger than the nozzle opening 131, even if an aggregate such as fine particles may adhere to the periphery of the liquid layer forming opening 211, the liquid is discharged from the liquid layer forming opening. Since this occurs at the center of the droplet, it has little effect on droplet ejection. For this reason, the deviation of the flying direction of the liquid droplet is unlikely to occur. Therefore, it is always possible to stably discharge droplets.

  FIG. 3 is a perspective view of a droplet discharge device showing another example of the present invention. The difference from FIG. 2 is that the second liquid supply channel is divided into a common channel 3121 and an individual channel 321 in order to smoothly supply the second liquid. The common flow path 311 has a wide flow path, and the liquid supply amount can be improved. In addition, the individual flow path 321 makes it easy to supply liquid evenly to each nozzle.

  In the example described above, an example in which the first liquid that does not contain particles or the like and has good discharge characteristics is used in the liquid discharge main body 100 with respect to the second liquid such as the fine particle-containing ink will be described. However, even if a liquid with a reduced particle content of the second liquid or a liquid with a reduced concentration is used as the first liquid, the problem of precipitation in the liquid discharge main body 100 is reduced. it is obvious.

  Further, the difference between the first liquid and the second liquid is not limited to whether or not the particles contain fine particles, and the composition of the solution can be changed. For example, the present invention may be implemented after increasing the viscosity of the liquid by increasing the component amount or molecular weight of the liquid used in the liquid discharge main body 100. In this case, in addition to the effect of suppressing the entry of the second liquid into the liquid discharge main body 100, the discharge of the first liquid from the nozzle opening 131 is suppressed, and the second liquid is discharged to the liquid layer 230. The discharge pressure action mainly works, and it is possible to prevent the liquid concentration of the droplet 20 from being lowered due to the discharge of the first liquid from the nozzle opening 131. Such an effect may be further exerted by making the two inks into inks having physical properties that are not mixed with each other.

  In contrast to the example of reducing or preventing the phenomenon of mixing of the two types of ink, a modification that positively uses the phenomenon of mixing can be realized. That is, by changing the waveform of the ejection drive pulse piezoelectric applied to the common electrode 1121 of the piezoelectric element 110, the amount of the first liquid ejected from the nozzle opening 131 and the pressure at which this ejection acts on the second liquid layer 230. To change. Thereby, it is possible to control the phenomenon of discharging as the droplet 20 with the second liquid of the liquid layer 230. Therefore, by such control, the ratio of the first liquid and the second liquid constituting the droplet 20 can be adjusted, and the concentration of the fine particles contained in the droplet 20 can be controlled.

  Further, as another example of the means for forming the liquid layer of the second liquid, the nozzle opening 131 of the orifice plate 130 and its peripheral portion are recessed from the orifice plate surface without using the ink layer forming plate 210. It can also be formed by forming a reservoir and supplying and filling the reservoir with a second liquid. As another example, the ink layer forming plate 210 is formed of a porous material, the ink layer forming plate is attached to the surface of the orifice plate 130, and the second liquid supplied through the porous material is added. The liquid layer of the second liquid can be formed by accumulating in the portion of the liquid layer forming opening 211 formed in front of the nozzle opening 131.

  The ink jet type droplet discharge apparatus according to the present invention is suitable for a serial scanning ink jet recording apparatus and a line scanning ink jet recording apparatus. In the serial scanning type ink jet recording apparatus, the liquid layer forming plate surface of the recording head according to the present invention is placed facing the recording medium, and the recording head is used as a recording signal in the transverse direction intersecting the continuous direction of the recording medium. Accordingly, the recording medium is moved (main scanning) while ejecting in response to record one line, and then the recording medium is fed by a predetermined amount in the continuous direction of the continuous recording medium (sub scanning), and then the next line image is main scanned. Record. The main scanning and the sub scanning are repeated to record an image. In the line scanning ink jet recording apparatus, a large number of recording heads according to the present invention are arranged in the width direction of the recording medium so as to face the recording medium surface to the full width, and droplets are ejected in accordance with a recording signal. At the same time, the recording medium is moved in the longitudinal direction of the continuous recording medium at high speed to perform main scanning. With this main scanning and droplet discharge control, recording dot formation on the scanning line is controlled to obtain a recorded image on a recording medium. According to such an ink jet recording apparatus according to the present invention, it is possible to print a high-quality image with high reliability.

  The present invention is not limited to an ink jet recording apparatus that records liquid on recording paper, but can be applied to industrial liquid dispensing apparatuses such as a marking device for products and a coating film apparatus.

1 is a schematic cross-sectional view of an ink jet type droplet discharge apparatus as an example of the present invention. The perspective view of FIG. The schematic structure perspective view of the inkjet type droplet discharge apparatus which becomes the other example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Recording head 20 Droplet 50 2nd liquid supply apparatus 55 2nd liquid collection | recovery part 60 1st liquid supply apparatus 100 Droplet discharge main-body part 101 1st flow path unit 103 Piezoelectric element unit 110 Piezoelectric element 111 Layered Piezoelectric Element 112 Layered Electrode 1121 Common Electrode 1122 Individual Electrode 1123 Residual Polarization 113 Piezoelectric Element Support Substrate 120 Diaphragm 122 Diaphragm Forming Plate 130 Orifice Plate 131 Nozzle Opening 140 Pressurizing Chamber 142 Channel Forming Plate 145 Introducing Restriction Unit 147 Inflow Path 150 Liquid chamber 160 Flexible cable 161 Flexible cable terminal 200 Liquid layer forming liquid supply unit 210 Liquid layer forming plate 211 Liquid layer forming opening 220 Channel forming plate 221 Supply channel 2211 Supply common channel 2212 Supply individual channel 222 Inflow channel 223 Recovery path 230 Body layer

Claims (4)

  The first liquid that does not contain fine particles is supplied into the pressurizing chamber through the introduction throttle, and is pressurized in the pressurizing chamber, so that the pressure is applied to the liquid layer of the second liquid containing fine particles from the nozzle opening. An ink jet type droplet discharge apparatus comprising: means for operating and discharging a second liquid as droplets; and means for forming a liquid layer of the second liquid containing fine particles on the front surface of the nozzle opening. .   The means for forming the liquid layer of the second liquid is arranged to hold a predetermined gap with the nozzle opening, and has an ink layer forming plate having a liquid layer forming opening at a position opposite to the nozzle opening, and a first portion in the gap. 2. An ink jet type droplet discharge apparatus according to claim 1, further comprising a liquid supply means for supplying two liquids.   The means for discharging the second liquid as droplets includes an orifice plate provided with the nozzle opening, a pressurizing chamber which is communicated with the nozzle opening and has one surface made of a flexible member, and the pressurizing chamber. An introduction throttle portion for introducing the first liquid into the chamber; a common liquid chamber for supplying the first liquid to the introduction throttle portion; a piezoelectric element that contacts the flexible member; and a fixed substrate that holds the piezoelectric element 3. An ink jet liquid droplet ejection apparatus according to claim 1, further comprising a piezoelectric element unit comprising an electrode for energizing the piezoelectric element.   A recording apparatus comprising the ink jet type droplet discharge device according to claim 1.

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