JP4042777B2 - Inkjet head - Google Patents

Description

  The present invention relates to an ink jet head of an ink jet recording apparatus that performs required recording on recording paper or the like by ejecting ink liquid from nozzles.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus is well known as a recording apparatus having a relatively simple configuration and easy high-speed printing and high-quality printing. An ink jet head of this type of ink jet recording apparatus has, for example, a nozzle plate formed with a plurality of nozzle holes for ejecting ink liquid, a piezoelectric ceramic material, and the like, and a plurality of ejection channels communicated with the nozzle holes. Actuators formed in a plurality of rows and joined to the actuators at the inlet end side of the ejection channels, extending in the arrangement direction of the plurality of ejection channels to supply ink liquid from the ink supply source to the ejection channels, and And a manifold in which a supply path that opens to each inlet end of the injection channel is formed.

  The ink jet head is disposed, for example, with the nozzle plate down and the manifold up, and is inclined at about 45 degrees, and the volume of the ejection channel is changed by deformation of the actuator. Is ejected obliquely downward from a nozzle hole formed in the nozzle plate and printed on a printing paper or the like. On the other hand, when the volume is increased, ink liquid is introduced from the ink supply source into the ejection channel of the actuator through the supply path. I am doing so.

  Further, the ink jet head may cause ejection failure due to bubbles generated or remaining in the ink jet head or ink droplets adhering to the ejection surface. For this reason, the ink jet recording apparatus is provided with a purge device that sucks and removes bubbles in the ink jet head together with the ink liquid and recovers the ink jet state.

Next, an ink jet head as a conventional example will be described more specifically with reference to the drawings. FIG. 7 is a cross-sectional view of an essential part showing an inkjet head 3 in which a plurality of ejection channels 2 are formed in the actuator 1 in two rows at a predetermined interval. A nozzle plate 5 is joined to the outlet end 4 side of the ejection channel 2, and the outlet end 4 of each ejection channel 2 communicates with a nozzle hole 6 formed in the nozzle plate 5. Further, a manifold 8 is joined to the inlet end 7 side of the injection channel 2, and the inlet end 7 of each injection channel 2 extends in the arrangement direction of the plurality of injection channels 2, and the inlet end of each injection channel 2. 7 communicates with a supply path 9 that is open to 7. Then, the ink liquid from the ink supply source is introduced into each ejection channel 2 from each inlet end 7 via the supply path 9 and ejected from the nozzle hole 6.
JP-A-9-57959

  However, the generation or residual of bubbles in the ink jet head mainly occurs in the supply path. Therefore, in the configuration shown in FIG. 7, bubbles generated or remaining in the supply path 9 stay on the upper wall side of the supply path 9 due to buoyancy or the like. The bubble 10 shown by the dotted line in FIG. 7 shows this state, and the bubble 10 grows with the passage of time and becomes a state like the bubble 11 shown by the solid line. Then, since the outer surface of the bubble 11 is close to the inlet end 7 of the ejection channel 2, the ink flow path is narrowed, and the flow rate of the ink liquid accompanying ejection is increased. As a result, the negative pressure acting on the outer surface of the bubble 11 is increased, and the bubble 11 is likely to be drawn by the ejection channel 2. When the bubbles 11 enter the ejection channel 2, ejection failure occurs and so-called print omission occurs.

  On the other hand, when such ejection failure occurs, the bubbles in the inkjet head 3 are purged using the purge device as described above, but the period during which the supply of ink liquid is hindered by the growth of the bubbles 10. If it is short, purge must be performed frequently, and the operation becomes complicated. Further, when the amount of wasted ink liquid is increased by purging, there is a problem that the amount of ink liquid used for printing is reduced accordingly.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an ink jet that can maintain a good printing state for a long time by reducing ejection failure due to generated and grown bubbles in a supply path. The head is provided.

In order to achieve the above object, according to the first aspect of the present invention, there is provided an actuator in which a plurality of ejection channels for ejecting ink liquid from nozzles are formed in a plurality of rows, and the inlet end side of the ejection channel. A joint that is joined to an actuator and extends in the direction of arrangement of each of the plurality of ejection channels and supplies a common opening to each inlet end of the ejection channels in order to supply ink liquid to each of the ejection channels. In the inkjet head, the ink flow path is formed on the end surface of the actuator facing the manifold, the ink flow path allowing the ink liquid to flow in the arrangement direction of the ejection channels. The ink flow path is arranged between the actuator and the manifold in the arrangement direction. Extending along the communication path and communicating adjacent to the injection channel from the direction orthogonal to the arrangement direction, and extending in the arrangement direction at the end face of the actuator on the inlet end side of the injection channel. An inclined surface is formed on the end surface between the injection channels, which forms the inlet end of the injection channel, so that the flow channel cross-sectional area of the injection channel increases toward the opening edge of the injection channel. Thus, the ink flow path is formed .

  According to such a configuration, even if bubbles generated or remaining in the supply path stay and grow on the upper wall side of the supply path, they face the actuator manifold between the grown bubbles and the injection channel. Since the ink flow path that allows the ink liquid to flow in the arrangement direction of the plurality of ejection channels is formed on the end surface, the ink liquid is not inhibited by the grown bubbles, It can be introduced well into the injection channel. Even if bubbles grow, if the ink flow path is formed, the flow path of the ink liquid generated by the ejection is secured, and the flow velocity does not increase and acts on the outer surface of the bubble. Since the negative pressure to be reduced is reduced, it is difficult for bubbles to be drawn into the injection channel, and a good injection state can be maintained for a long time. Therefore, it is not necessary to frequently perform a purge operation, and operability can be improved.

  That is, in general, the purge operation is performed when a predetermined period or more has elapsed since the previous purge operation was performed before performing the printing operation. During this predetermined period, bubbles that have grown in the manifold are generated. It is determined assuming a period that affects the injection. Therefore, if the predetermined period determined thereby is short, as a result, the purge operation is frequently performed and the amount of ink liquid consumed for printing is reduced. However, in the present invention, this predetermined period can be lengthened. Therefore, the amount of ink liquid consumed for printing is not reduced for this reason. In addition, if the predetermined period is short for the user who performs the printing operation, the purge operation is executed before printing, so that it takes a lot of time to complete the printing output. However, in the present invention, since it is not necessary to frequently perform the purge operation before printing, it does not take much time to complete the print output, and therefore, good operability is achieved. Can do.

In addition , even if bubbles generated or remaining in the supply path stay and grow on the upper wall side of the supply path, the ink liquid is not blocked by the grown bubbles and is ejected through this ink flow path. Can be successfully introduced into.

In addition , the ink flow path is formed in the supply path with a simple configuration because the ink flow path is formed simply by forming an inclined surface on the end surface that forms the inlet end portion of the ejection channel at the end surface between the ejection channels. Further, it is possible to reduce ejection failures due to the bubbles that have grown, and to maintain a good printing state for a long time.

According to a second aspect of the present invention, in the first aspect of the present invention, the supply path has a branch portion that opens in common with each of the plurality of rows of the injection channels. It is characterized by.

  By forming such a branch portion, the volume of the supply path can be further reduced, the ink jet head can be further reduced in size, and the ink liquid flowing into the supply path is discharged from the branch portion to each ejection channel for each column. Can be supplied smoothly.

The invention according to claim 3 is characterized in that, in the invention according to claim 2 , the plurality of injection channels are formed in two rows, and the supply path has two branch portions. Yes.

  When a plurality of injection channels are formed in two rows, the injection channels in the actuator can be most effectively arranged, the actuator can be easily formed, and the supply path in the manifold can be easily formed. Therefore, an excellent ink jet head can be efficiently manufactured, and the ink jet head can be further downsized.

The invention according to claim 4 is the invention according to any one of claims 1 to 3 , characterized in that an inner volume of the ink flow path is smaller than an inner volume formed by the manifold. .

  According to such a configuration, since the internal volume of the ink flow path formed on the actuator side is smaller than the internal volume formed by the manifold, the increase in the internal volume of the entire supply path is slight. For this reason, the amount of ink liquid sucked by the purge device is small, and the burden on the maintenance system including the purge device can be reduced.

  According to the first aspect of the present invention, it is not necessary to frequently perform the purge operation, and the operability can be improved.

Further , even when bubbles generated or remaining in the supply path grow, the ink liquid can be satisfactorily introduced into the ejection channel through the ink flow path without being inhibited by the grown bubbles.

In addition , with a simple configuration, it is possible to reduce ejection failure due to bubbles generated and grown in the supply path, and it is possible to maintain a good printing state for a long time.

According to the second aspect of the present invention, the ink jet head can be further reduced in size, and the ink liquid flowing into the supply path can be smoothly supplied from the branch portion to each ejection channel in each row.

According to the invention described in claim 3 , an excellent ink jet head can be efficiently manufactured, and the ink jet head can be further reduced in size.

According to the invention described in claim 4 , it is possible to reduce the burden on the maintenance system including the purge device.

  FIG. 1 is a perspective view of an inkjet printer including an inkjet head according to an embodiment of the present invention.

  The color ink jet printer 21 includes an ink jet type ink jet head 23 that performs printing by printing four color inks of cyan, magenta, yellow, and black on a printing paper 22 as a printing medium. The head unit 24 is integrally provided as a head unit 24. The head unit 24 is supported by a carriage 26 so that the ink jet head 23 ejects ink liquid obliquely downward with respect to the printing paper 22. The head unit 24 In addition, an ink cartridge 25 as an ink supply source for supplying four color ink liquids to the inkjet head 23 is detachably mounted on the carriage 26.

  A platen roller 27 is rotatably provided facing the front surface of the ink jet head 23 in parallel with the reciprocating direction thereof, and the ink jet head 23 and the platen roller 27 constitute a printing unit. The carriage 26 is supported by a carriage shaft 29 extending in the reciprocating movement direction of the inkjet head 23 and a guide plate 54 via a carriage shaft support portion 28 provided at the lower portion of the carriage 26, and can linearly reciprocate during printing. In addition, the pulley 30 is connected to a belt 32 spanned between the pulleys 30 and 31, and the pulley 30 is rotationally driven by a motor (not shown) so as to be linearly reciprocated.

  The printing paper 22 is fed from a paper feeding cassette (not shown) provided above the rear part of the ink jet printer 21 and is introduced between the ink jet head 23 and a platen roller 27 that is rotationally driven in the direction of the arrow 33. The printing paper 22 is discharged in the direction of the arrow 34. In FIG. 1, the illustration of the paper feeding mechanism for these printing papers is omitted.

  Further, a purge device 35 is provided on the side of the platen roller 27 so as to face the front of the reset state position of the inkjet head 23. The ink jet type ink jet head 23 may cause ejection failure due to generation or remaining of bubbles in the inside thereof, or adhesion of ink droplets on the ejection surface. Therefore, there is a purge device 35 for sucking and removing air bubbles in the ink jet head 23 together with the ink liquid and recovering a good ejection state. The purge device 35 can cover the inkjet head 23 with a cap 36 provided at a front facing position in the reset state position of the inkjet head 23, and when the inkjet head 23 is covered with the cap 36, Defective ink containing bubbles and the like accumulated inside the ink jet head 23 is sucked by the pump 38 driven by the cam 37 to recover the ink jet head 23. The sucked defective ink is sent to the storage unit 39.

  FIG. 2 is a cross-sectional view of the main part of the head unit 24.

  In FIG. 2, the inkjet head 23 is formed of a nozzle plate 12 in which a plurality of nozzle holes 67 for ejecting ink liquid is formed, a piezoelectric ceramic material, and the like, and communicates with each nozzle hole 67 at an outlet end 68 thereof. In order to supply ink liquid to each of the ejection channels 13, the plurality of ejection channels 13 are joined to the actuator 14 on the inlet end 15 side of the ejection channel 13 and a plurality of ejection channels 13 are formed. And a manifold 17 formed with a supply passage 16 that is open in common to the inlet ends 15 of the injection channels 13.

  Then, as described above, the inkjet head 23 is disposed with the nozzle plate 12 down and the manifold 17 up and inclined by about 45 degrees, and the volume of the ejection channel 13 is changed by deformation of the actuator 14. When the volume decreases, the ink liquid in the ejection channel 13 is ejected obliquely downward from the nozzle hole 67 formed in the nozzle plate 12 to print on the printing paper 22, while when the volume increases, the ink cartridge 25 passes through the supply path 16. Ink liquid is introduced into the ejection channel 13 of the actuator 14. The inkjet head 23 may be a thermal head type using a heat generating element instead of the piezoelectric ceramic element or other known type.

  Then, a through hole 19 is formed in the vertical wall 18 of the head unit 24, the inlet 20 side of the manifold 17 is inserted into the through hole 19, and the manifold 17 and the vertical wall 18 of the head unit 24 are bonded together. The inkjet head 23 is attached to the head unit 24. In addition, a seal member 40 is fitted in a gap between the inlet 17 side of the manifold 17 and the through hole 19, and a first portion is formed between the seal member 40 and the opening of the inlet 20. A filter 41 is interposed. The first filter 41 prevents dust and bubbles from entering the supply path 16 of the inkjet head 23 when the ink cartridge 25 is connected to the seal member 40.

  An adapter 43 for connecting to the seal member 40 is fitted into the ink supply port 42 of the ink cartridge 25 housed in the head unit 24. A second filter 44 is interposed between the ink supply port 42 and the adapter 43. The second filter 44 prevents the ink liquid from spilling from the ink supply port 42 when the ink cartridge 25 is connected to the inkjet head 23 due to the surface tension of the ink liquid in the second filter 44. is there.

  The ink supply port 42 of the ink cartridge 25 and the inlet 20 of the manifold 17 are detachably connected by fitting the adapter 43 and the seal member 40 together. The ink liquid in the ink cartridge 25 is introduced into the inflow port 20 from the ink supply port 42 via the adapter 43 and the seal member 40. Reference numeral 45 denotes a head cover that covers the inkjet head 23.

  3 is a cross-sectional view taken along line AA in FIG. 2, and FIG. 4 is a cross-sectional view taken along line BB in FIG. FIG. 5 is a cross-sectional view taken along the line C-C in FIGS. 3 and 4. Before describing an ink jet head according to an embodiment of the present invention, a reference form will be described.

  As shown in FIG. 3, the actuator 14 includes a pair of substrates 46 and 47 having piezoelectric ceramic elements and a plate 48 sandwiched between the pair of substrates 46 and 47. A plurality of independent grooves 49 and 50 are formed. Then, by joining the substrates 46 and 47 to both side surfaces 65 and 66 of the plate 48, the outer wall and the side wall are formed by the grooves 49 and 50, and the inner wall is formed by the side surfaces 65 and 66 of the plate 48. A plurality of injection channels 13 are formed. The plurality of formed injection channels 13 are arranged in two rows so as to face each other with the plate 48 interposed therebetween.

  As shown in FIG. 4, the supply path 16 of the manifold 17 is bifurcated from the inflow position from the inflow port 20, and is common to each row of the plurality of injection channels 13 formed in two rows. Have two branch portions 51 and 52 which are open. The ink liquid that has flowed into the supply path 16 from the inlet 20 is divided and flows into the branch portions 51 and 52, and flows through the branch portions 51 and 52. Introduced in.

  As shown in FIG. 5, the end face 55 and 56 of the substrates 46 and 47, which are the end faces on the inlet end 15 side of the injection channel 13 of the actuator 14 and located outside the injection channels 13, and the manifold 17 The inkjet head 23 is configured by joining end surfaces 58 and 59 on the opening side end surface of the supply path 16 and outside the branch portions 51 and 52.

  In such a configuration, in the reference form shown in FIG. 5, the end surface 57 of the plate 48 positioned between the ejection channels 13 extending in the arrangement direction is set to be a nozzle with respect to the end surfaces 55 and 56 of the substrates 46 and 47. A gap is formed between the end surface 60 on the inner side of the branch portions 58 and 59 and the end surface 57 of the plate 48 so as to be positioned on the plate 12 side. In addition, the ink flow path 53 that allows the ink liquid to flow in the arrangement direction of the plurality of ejection channels 13 and between the rows of the ejection channels 13, that is, in the direction perpendicular to the ejection channel rows, is formed with the gap. .

  By forming such an ink flow path 53, bubbles generated or remaining in the supply path 16 stay on the upper wall side of the supply path 16 due to buoyancy or the like (the state of the bubbles 61 shown by the dotted line in FIG. 5). Even when the ink liquid grows with time and reaches a state like a bubble 62 shown by a solid line in FIG. 5, the ink liquid is not blocked by the grown bubble 62 and passes through the ink channel 53 in the ejection channel. 13 flow in the direction of arrangement and perpendicular to it, and can be successfully introduced into the injection channel 13 in sequence. Even if the growth of the bubble 61 proceeds, if the ink flow path 53 is formed, the flow path of the ink liquid generated by the ejection is ensured, and the flow velocity does not increase, and the grown bubble 62 Since the negative pressure acting on the outer surface of the gas becomes small, the bubbles 62 are not easily drawn into the ejection channel 13, and a good ejection state can be maintained for a long time. Therefore, it is not necessary to frequently perform a purge operation, and operability can be improved.

  That is, in general, the purge operation is performed when a predetermined period or more has elapsed since the previous purge operation was performed before the printing operation. This predetermined period is a period of bubbles grown in the manifold 17. Is determined assuming a period that affects injection. Therefore, if the predetermined period determined thereby is short, the purge operation is frequently performed as a result, and the amount of ink liquid consumed for printing is reduced. In the present embodiment, the predetermined period is increased. Therefore, the amount of ink liquid consumed for printing is not reduced for this reason. In addition, if the predetermined period is short for the user who performs the printing operation, the purge operation is executed before printing, so that it takes a lot of time to complete the printing output. However, in the present embodiment, since it is not necessary to frequently perform the purge operation before printing, it does not take much time to complete the print output, and therefore, good operability is achieved. be able to.

  In addition, in this embodiment, the internal volume of the ink flow path 53 formed on the actuator 14 side is sufficiently smaller than the internal volume formed by the manifold 17, so that the increase in the internal volume of the entire supply path 16 is not increased. Is slight. Therefore, the amount of ink liquid sucked by the purge device 35 is small, and the burden on the maintenance system including the purge device 35 can be reduced.

  Further, since the ink flow path 53 is formed only by positioning the end face 57 of the plate 48 on the nozzle plate 12 side with respect to the end faces 55 and 56 of the substrates 46 and 47, the ink flow path 53 has a simple configuration. 53 is formed, and the ejection failure due to the bubbles 62 generated and grown in the supply path 16 is reduced.

  The actuator 14 has a plurality of injection channels formed in two rows, and the supply path 16 has two branch portions 51 and 5 corresponding to the rows of the injection channels 13. Therefore, the injection channels 13 in the actuator 14 are most effectively arranged and the actuator 14 can be easily formed. On the other hand, the manifold 17 also has two branch portions 51 and 52, so that the supply path 16 The volume can be further reduced and the inkjet head 23 can be reduced in size, and the ink liquid flowing into the supply path 16 is smoothly supplied from the branch portion 51 to each ejection channel 13 for each column. In particular, since two branch portions are formed, the supply path 16 in the manifold 17 can be easily formed, an excellent ink jet head 23 can be efficiently manufactured, and the ink jet head 23 can be further downsized. Yes.

  FIG. 6 is a cross-sectional view of an inkjet head according to an embodiment of the present invention. In FIG. 6, parts corresponding to the parts shown in FIG. 5 described above are denoted by the same reference numerals as in FIG.

  In the inkjet head 23 shown in FIG. 6, the end surface 57 of the plate 48 between the ejection channels 13 on the end surface of the ejection channel 13 in the actuator 14 on the inlet end 15 side, which forms the inlet end of the ejection channel 13. The ink flow path 53 is formed by forming inclined surfaces 63 and 64 on the end face such that the flow channel cross-sectional area of the ejection channel 13 increases toward the opening edge of the ejection channel 13.

  More specifically, as shown in FIG. 6, the end surface 57 of the plate 48 is flush with the end surfaces 55 and 56 of the substrates 46 and 47 on the end surface on the inlet end 15 side of the ejection channel 13 in the actuator 14. Further, inclined surfaces 63 and 64 are formed by chamfering inwardly toward the end surface 57 of the plate 48 over the entire length of the row of the injection channels 13 on the end surface 57 side of the both side surfaces 65 and 66 of the plate 48. is doing. And the end surfaces 57 and 56 of the substrates 46 and the outer end surfaces 58 and 59 of the branch portions 51 and 52 are joined together, and the end surface 57 of the plate 48 is connected to the inner end surfaces of the branch portions 51 and 52. 60. The ink flow path 53 is formed inside the inlet end 15 of each of the expanded ejection channels 13 by the inclined surfaces 63 and 64. According to such a configuration, only the inclined surfaces 63 and 64 are formed on the end surface forming the inlet end portion of the injection channel 13, in other words, the end edges of both side surfaces 65 and 66 of the plate 48 are chamfered. Thus, the ink flow path 53 can be formed, so that the ink flow path 53 can be formed with a simple configuration, and the ejection failure caused by the bubbles 62 generated and grown in the supply path 16 can be reduced as in the embodiment shown in FIG. it can.

  In addition, the inkjet head 23 can also place a nozzle horizontally horizontally or vertically downward. In the case of horizontal orientation, it is desirable to arrange the supply path 16 below with the inlet 20 facing upward. In either case, substantially the same effect can be achieved.

1 is a perspective view of an inkjet printer including an inkjet head according to an embodiment of the present invention. It is principal part sectional drawing of the head unit with which the inkjet printer shown in FIG. 1 is equipped. It is principal part sectional drawing of the AA in FIG. It is sectional drawing of the BB line in FIG. It is principal part sectional drawing of CC line | wire in FIG. 2, and has shown the form used as reference when describing one Embodiment of this invention. It is principal part sectional drawing of the CC line in FIG. 2, and is sectional drawing of the inkjet head which concerns on one Embodiment of this invention. It is sectional drawing of the conventional inkjet head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 13 Ejection channel 14 Actuator 15 Inlet end 16 Supply path 17 Manifold 23 Inkjet head 25 Ink cartridge 53 Ink flow path 57 End surface 55,56 End surface 63,64 Inclined surface 51,52 Branch part

Claims (4)

A plurality of ejection channels for ejecting ink liquid from the nozzles are joined to the actuators formed in a plurality of rows and the actuator on the inlet end side of the ejection channel, and the ink liquid is supplied to each of the ejection channels. A plurality of ejection channels extending in the direction of arrangement of the ejection channels and a manifold formed with a supply passage that is commonly open to the inlet ends of the ejection channels.
Forming an ink flow path on the end face of the actuator facing the manifold, in which an ink liquid can flow in the arrangement direction of the plurality of ejection channels ;
The ink flow path extends along the arrangement direction between the actuator and the manifold and communicates with the supply path, and communicates with the ejection channel adjacently from a direction perpendicular to the arrangement direction. ,
On the end face of the injection channel on the inlet end side of the actuator, the end face between the injection channels extending in the arrangement direction, and the end face forming the inlet end of the injection channel, toward the opening edge of the injection channel. An ink jet head characterized in that the ink flow path is formed by forming an inclined surface in which the flow path cross-sectional area of the ejection channel is widened . The inkjet head according to claim 1 , wherein the supply path has a branch portion that is opened in common corresponding to each of the plurality of rows of the ejection channels. The inkjet head according to claim 2 , wherein the plurality of ejection channels are formed in two rows, and the supply path has two branch portions. The internal volume of the ink flow path, characterized in that less than the internal volume formed by the manifold, the ink-jet head according to any one of claims 1 to 3.

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