JP2013000910A - Liquid ejecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circulation type liquid ejecting apparatus suppressing unevenness of density of discharged liquid.SOLUTION: The liquid ejecting apparatus includes a plurality of heads each having nozzles 21 discharging ink supplied by a circulation flow passage, a nozzle row 21A formed by lining up the nozzles 21 in a first direction and a manifold 101 communicated with the nozzles 21. In the pair of heads 1a, 1b juxtaposed in a second direction intersecting with the first direction, an ink flowing direction A in the manifold 101 of the head 1a and an ink flowing direction B in the manifold 101 of the head 1b are reverse to each other.

Description

The present invention relates to a liquid ejecting apparatus, and more particularly to an ink jet recording apparatus that ejects ink as a liquid.

As an ink jet recording apparatus which is an example of a liquid ejecting apparatus, an ink jet recording apparatus is known in which an ink tank is provided apart from an ink jet recording head and ink is circulated between the ink tank and the ink jet recording head. (For example, refer to Patent Document 1).

The ink jet recording head has a nozzle array composed of a plurality of nozzles, an individual flow path (such as a pressure generation chamber) for supplying ink to each nozzle, and a common flow path common to the individual flow paths. In a circulation type ink jet recording apparatus, ink is supplied from an ink tank to one end (inlet side) of a common flow path. Ink supplied from the inlet side of the common channel flows to the other end side (outlet side), and part of the ink flows into the individual channel and is ejected as ink droplets from the nozzle. Then, the ink that has not flowed into the individual flow path is collected into the ink tank from the outlet side of the common flow path.

By circulating the ink in this manner, it is possible to suppress the precipitation of components such as pigments in the ink.

JP 2009-23289 A (refer to FIG. 3 etc.)

While ink flows from the inlet side to the outlet side of the common channel, a part of the ink flows into the individual channel, so that the ink pressure gradually decreases from the inlet side to the outlet side of the common channel. . As described above, since the ink pressure gradient is generated from the inlet side to the outlet side of the common flow path, the characteristics of the ink droplets ejected from the nozzle, such as weight, shape, and speed, are different between the inlet side and the outlet side of the common flow path. Different.

If there is a difference in ink ejection characteristics due to such a pressure gradient, the ink ejected from the individual channels / nozzles closer to the outlet side of the common channel has a smaller ink droplet shape, and the ink printed on the paper surface. This causes unevenness in the density.

Such a problem exists not only in a liquid ejecting apparatus using an ink jet recording head but also in a liquid ejecting apparatus using a liquid ejecting head that ejects liquid other than ink.

In view of such circumstances, it is an object of the present invention to provide a circulation type liquid ejecting apparatus that suppresses uneven density of discharged liquid.

An aspect of the present invention that solves the above-described problems is a nozzle row in which nozzles for discharging liquid are arranged in the first direction, an individual channel having a pressure generation chamber that communicates with the nozzle, and a common channel that communicates with the individual channel. A liquid jet head having a flow path, a pressure generating means for generating a pressure change in the pressure generating chamber, a supply path for supplying liquid from the outside to the common flow path, and a recovery for recovering liquid from the common flow path to the outside A liquid flow path including a passage, and the liquid jet heads are arranged in parallel in a second direction intersecting the first direction so that a liquid flow direction in the common flow path of the liquid jet heads is reversed. The liquid ejecting apparatus is characterized by the above.
In this aspect, the flow direction of the liquid in each common flow path of the liquid jet heads (hereinafter referred to as a pair of liquid jet heads) arranged in parallel in the second direction so that the flow direction of the liquid in the common flow path is reversed. They are opposite to each other. As a result, the concentration gradient of the liquid ejected from one liquid ejecting head and the concentration gradient of the liquid ejected from the other liquid ejecting head are reversed, and the entire liquid ejected by these pair of liquid ejecting heads Then, the density becomes equal. As described above, in the liquid ejecting apparatus according to the invention, it is possible to perform high-quality printing by circulating the liquid through the circulation flow path and preventing uneven concentration of the liquid.

Here, it is preferable that the positions of the nozzles in the first direction are aligned in the liquid jet heads arranged side by side so that the liquid flow direction in the common flow path is reversed. According to this, one droplet is formed from each nozzle of the pair of liquid jet heads, and the liquid is ejected with a uniform concentration as a whole.

Further, the liquid jet heads arranged in parallel so that the liquid flow direction in the common flow path is opposite to each other, each nozzle in the first direction of one liquid jet head is the same as that of the other second liquid jet head. It is preferably located between the nozzles in the first direction. According to this, it is possible to discharge droplets with a uniform density and a high density.

In addition, it is preferable that the circulation flow path is provided for each of the liquid jet heads arranged in parallel so that the liquid flow direction in the common flow path is opposite. According to this, it is possible to prevent the pressure loss that may occur in the pair of liquid ejecting heads from affecting the other pair of liquid ejecting heads.

Further, it is preferable that the circulation flow path is provided in common for the plurality of liquid ejecting heads. According to this, the number of members constituting the circulation channel can be reduced.

In addition, it is preferable that the circulation flow path is provided for each liquid ejection head having a plurality of the liquid ejection heads and having the same liquid flow direction in the common flow path. According to this, it is possible to prevent the pressure loss that may occur in one liquid ejecting head of the pair of liquid ejecting heads from affecting the other liquid ejecting head.

1 is a perspective view illustrating a schematic configuration of an ink jet recording apparatus. It is a cross-sectional schematic diagram of a head. It is a disassembled perspective view which shows schematic structure of a head. It is the top view and sectional drawing of a head. It is a schematic diagram which shows the structure of a liquid flow path. It is a top view which shows the manifold of a head, a nozzle, and an ink drop. It is a top view which shows the manifold of a head, a nozzle, and an ink drop. It is a schematic diagram which shows the structure of the liquid channel which concerns on a modification. It is a schematic diagram which shows the structure of the liquid channel which concerns on a modification. It is a schematic diagram which shows the structure of the liquid channel which concerns on a modification.

<Embodiment 1>
Hereinafter, the present invention will be described in detail based on embodiments. Hereinafter, the ink jet recording head is an example of a liquid ejecting head, and is also simply referred to as a head. The ink jet recording apparatus is an example of a liquid ejecting apparatus.

FIG. 1 is a perspective view showing a schematic configuration of an ink jet recording apparatus. The ink jet recording apparatus I is a so-called line ink jet type that performs printing by fixing a head unit II having a plurality of heads 1 to the apparatus main body 2 and transporting an ejection medium such as a recording sheet S in the transport direction. It is a recording device.

The head unit II is configured by holding a plurality of heads 1 on a base plate 18 held by a frame member 19. The head unit II is fixed to the apparatus main body 2 via a frame member 19.

The apparatus main body 2 is provided with a paper feed roller 3. The paper feed roller 3 conveys a recording sheet S such as paper fed to the apparatus main body 2 in a second direction orthogonal to the first direction, and passes the recording sheet S through the ink ejection surface side of the head 1. . Here, the first direction is a direction in which nozzles of the head 1 described later are arranged in parallel, and the second direction is a direction orthogonal to the first direction (FIG. 2).
See 4. ). In the present embodiment, the second direction is also a relative movement direction of the recording sheet S and the head 1.

In the head unit II, eight heads 1 are arranged in four rows in the first direction and two rows in the second direction. One of the two heads 1 arranged in parallel in the second direction is the head 1a, and the other is the head 1.
Also called b. In the present embodiment, four pairs of heads 1 including the head 1a and the head 1b are provided in the first direction. Hereinafter, when referring to a pair of heads, the reference numeral “1” is used.
“a, 1b” is used, and reference is made to “1” when referring to a pair of heads without distinction. The head 1a and the head 1b are examples of liquid jet heads arranged side by side in the second direction. Although details will be described later, ink (liquid) in a common flow path (manifold 101) of the heads 1a and 1b. It is arrange | positioned so that the distribution direction of may become reverse direction.

Based on the print data representing the image printed on the recording sheet S, the control unit 4 transmits a signal to the paper feed roller 3 to convey the recording sheet S, and each head 1 via a wiring (not shown). A drive signal is transmitted to the ink to discharge ink.

The apparatus main body 2 is provided with an ink tank 5 in which ink is stored. The ink tank 5 is provided with a circulation flow path 8 serving as a flow path for ink supplied to the head 1 and ink recovered from the head 1.

The circulation flow path 8 is a supply pipe 6 that is a flow path for supplying ink from the ink tank 5 to each head 1.
And a collection pipe 7 which is a flow path for collecting ink from each head 1 to the ink tank 5. Although details will be described later, the ink is supplied from the ink tank 5 to the manifold (common flow path) of each head 1 through the supply pipe 6 by the circulation flow path 8, and the ink that has not been ejected from the nozzle openings is collected in the recovery pipe. The ink is collected in the ink tank 5 through 7.

The head according to the present embodiment will be described based on FIG. As shown in the figure, the head 1 includes a head main body 100 that ejects ink, and a flow path member 170 having an ink flow path interposed between the head main body 100 and the circulation flow path 8.

The flow path member 170 is provided in the ink supply port 110 that is an opening provided on the upper surface thereof, the upper supply path 120 that communicates with the ink introduction port 110, and the upper supply path 120.
A filter chamber 130 having an inner diameter wider than 20, and a filter chamber 130
And a lower supply path 160 provided on the downstream side.

A supply branch 62 constituting a part of the circulation channel 8 (see FIG. 1) is connected to the ink introduction port 110, and ink from the circulation channel 8 is supplied to the upper supply channel 120. Furthermore, the lower supply path 1
Reference numeral 60 denotes a manifold 101 which is a common flow path of the head main body 100, and ink is supplied to the manifold 101 from the lower supply path 160.

A filter chamber 130 provided between the upper supply path 120 and the lower supply path 160.
Is provided with a filter 131.

The filter 131 may be in the form of a sheet having the filter holes 132, for example, a sheet-like one in which a plurality of fine holes are formed by finely knitting metal, or one in which a fine work is formed on a metal plate. Can be used. The filter 131 prevents bubbles, dust, and the like in the ink from flowing into the downstream side of the filter 131, that is, the manifold 101. This suppresses ejection defects such as missing dots due to bubbles and the like, and nozzle clogging due to dust in the ink.

Further, the flow path member 170 includes an ink discharge port 150 which is another opening on the upper surface thereof, and a recovery path 140 which communicates with the ink discharge port 150. The collection path 140 is connected to the manifold 10.
1, a recovery branch pipe 72 constituting a part of the circulation flow path 8 (see FIG. 1) is connected to the ink discharge port 150. Ink that has not been ejected from the nozzles 21 flows into the collection path 140 from the manifold 101 and is discharged to the collection branch 72 through the ink discharge port 150.

The head main body 100 will be described in detail with reference to FIGS. FIG. 3 is an exploded perspective view of the head main body, and FIG. 4 is a plan view of the head main body and a sectional view taken along line AA ′.

As shown in the drawing, the flow path forming substrate 10 is made of a silicon single crystal substrate, and an elastic film 50 made of, for example, silicon dioxide is formed on one surface thereof. A plurality of pressure generating chambers 12 partitioned by a plurality of partition walls 11 are formed in the flow path forming substrate 10 in the first direction (pressure generation) by anisotropically etching the flow path forming substrate 10 from the other direction side. The chambers 12 are juxtaposed in the width direction (short direction). In addition, an ink supply path 14 and a communication path 15 are partitioned by a partition wall 11 on one end side in the longitudinal direction of the pressure generating chamber 12 of the flow path forming substrate 10. In addition, a communication portion 13 that forms a part of the manifold 101 serving as a common ink chamber (common flow path) for each pressure generation chamber 12 is formed at one end of the communication passage 15. In the present embodiment, the individual flow path of the claims includes a pressure generation chamber 12, a communication portion 13, an ink supply path 14, and a communication path 15.

On the opening surface side of the flow path forming substrate 10, a nozzle plate 20 in which a nozzle 21 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is formed is an adhesive or a heat welding film. It is fixed by an adhesive layer such as. The nozzle plate 20 is made of glass ceramics, a silicon single crystal substrate, stainless steel, or the like.

The nozzles 21 are arranged side by side in the first direction, and a nozzle row 21 </ b> A is configured from the plurality of nozzles 21 arranged in parallel.

An insulating film 55 made of, for example, zirconium oxide (ZrO ₂ ) or the like is laminated on the elastic film 50 described above on the side opposite to the opening surface of the flow path forming substrate 10. On the insulator film 55, a piezoelectric element 300 including a first electrode 60, a piezoelectric layer 70, and a second electrode 80 is formed as pressure generating means. Here, the piezoelectric element 300 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In this case, any one of the patterned electrodes and the piezoelectric layer 7 is used.
A portion that is composed of 0 and generates piezoelectric distortion when a voltage is applied to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the first electrode 60 is a common electrode of the piezoelectric element 300, and the second electrode 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. In any case, a piezoelectric active part is formed for each pressure generating chamber 12. In the above-described example, the elastic film 50, the insulator film 55, and the first electrode 60 function as a vibration plate, but of course not limited thereto, for example, the elastic film 50 and the insulator film 5
5 may be provided, and only the first electrode 60 may act as a diaphragm.

The second electrode 80 of each piezoelectric element 300 is connected to a lead electrode 90 made of, for example, gold (Au) or the like, and the piezoelectric element 300 is connected via the lead electrode 90.
A voltage is selectively applied to the.

The protective substrate 30 is bonded to the flow path forming substrate 10 via the adhesive 35 on the piezoelectric element 300 side. The protective substrate 30 is provided with a manifold portion 31 in a region facing the communication portion 13, and the manifold portion 31 is connected to the communication portion 13 of the flow path forming substrate 10 as described above.
Manifold 101 that is in communication with each other and serves as a common ink chamber (common flow path) for each pressure generating chamber 12
Is configured. A through hole 33 that penetrates the protective substrate 30 in the thickness direction is provided in a region between the piezoelectric element holding portion 32 and the manifold portion 31 of the protective substrate 30.
A part of the first electrode 60 and the leading end of the lead electrode 90 are exposed inside, and a driving circuit 250 for driving the piezoelectric element 300 is electrically connected to the leading end via the conductive wire 121. Yes.

As the protective substrate 30, it is preferable to use substantially the same material as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, ceramic material, etc. In this embodiment, the same material as the flow path forming substrate 10, that is, A silicon single crystal substrate having a (110) plane crystal plane orientation was used.

On the protective substrate 30, a compliance substrate 40 comprising a sealing film 41 and a fixing plate 42.
Are joined. The sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film), and one surface of the manifold portion 31 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal (for example,
Stainless steel (SUS) or the like. Since the region of the fixing plate 42 facing the manifold 101 is an opening 43 that is completely removed in the thickness direction, the manifold 1
One surface of 01 is sealed only with a flexible sealing film 41.

The compliance substrate 40 is provided with a first opening 44 and a second opening 45 (see FIG. 2). As described above, the lower supply path 160 (see FIG. 2) communicates with the first opening 44. The recovery path 140 (see FIG. 2) communicates with the second opening 45.

In the head main body 100 of this embodiment, the manifold 1 is connected from the ink tank 5 (see FIG. 1) through the circulation flow path 8 (supply branch pipe 62), the lower supply path 160 of the flow path member 170, and the like.
Ink is supplied to 01, and the ink passes through the manifold 101 from the first opening 44 to the second opening 4.
It circulates toward the 5th side. A part of the ink in the manifold 101 flows into the communication path 15, the ink supply path 14, and the pressure generation chamber 12 which are individual flow paths. Then, in accordance with a recording signal from a drive circuit (not shown), a voltage is applied between each of the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12, and the elastic film 50, the insulator film 55, the first film By bending and deforming the electrode 60 and the piezoelectric layer 70, the pressure in each pressure generating chamber 12 is increased and ink droplets are ejected from the nozzle 21.

On the other hand, ink that has not flowed into the individual flow path such as the pressure generation chamber 12 enters the ink tank 5 via the second opening 45, the recovery path 140 of the flow path member 170, and the circulation path 8 (recovery branch pipe 72). To be recovered. As described above, since the ink flows through the entire flow path including the common flow path, the components such as pigments contained in the ink are prevented from settling.

Further, in the manifold 101 of the head 1, ink that does not flow into the individual flow path (the pressure generation chamber 12 or the like) flows along the direction from the first opening 44 toward the second opening 45. Hereinafter, the direction of ink flow in the manifold 101 is referred to as a flow direction. In this embodiment, the distribution direction is parallel to the first direction.

The circulation channel will be described in detail with reference to FIG. The hatches in FIG. 5 represent the ink flowing through the circulation flow path, the head manifold 101 (common flow path), and the like, and the arrows indicate the direction of ink flow (
Distribution direction).

The ink jet recording apparatus I according to the present embodiment has a plurality of heads 1 as described above, and a pair of heads 1a and 1b arranged in the second direction are arranged in four rows in the first direction. Has been.

The circulation channel 8 includes a supply pipe 6 and a recovery pipe 7. In the present embodiment, one circulation channel 8 is provided for the four heads 1a, and one circulation channel 8 is provided for the four heads 1b.

The supply pipe 6 includes a single supply trunk pipe 61 connected to the ink tank 5 and a supply branch pipe 62 that connects the supply trunk pipe 61 and the ink introduction port 110 of the head 1. The collection pipe 7 includes a single collection trunk pipe 71 connected to the ink tank 5 and a collection branch pipe 72 that connects the collection trunk pipe 71 and the ink discharge port 150. A pump P is interposed between the recovery trunk pipe 71 and the ink tank 5. Due to the negative pressure generated by the pump P, the ink of each head 1 is recovered from the head 1 to the ink tank 5 via the recovery pipe 7. Ink is circulated by supplying ink from the ink tank 5 to the head 1 via the supply pipe 6.

The flow direction of ink in the manifold 101 and the ejected ink will be described in detail with reference to FIG.

FIG. 6A is a plan view schematically showing a manifold of a pair of heads.
) Is a plan view schematically showing the nozzles of a pair of heads, and FIG. 6C is a plan view schematically showing ink droplets ejected from each of the pair of heads. (D) is a plan view schematically showing ink droplets ejected from a pair of heads.

As shown in FIG. 6A and FIG. 5 described above, in the head 1a, the upstream side (first opening 44 side) in the ink circulation direction in the manifold 101 is one end side in the first direction (left side in FIG. 6). The downstream side (second opening 45 side) is located on the other end side in the first direction (right side in FIG. 6). on the other hand,
In the head 1b, the upstream side (first opening 44 side) in the ink flow direction in the manifold 101 is positioned on the other end side (right side in FIG. 6) in the first direction, and the downstream side (second opening 45 side). It is located on one end side in the first direction (left side in FIG. 6).

By connecting the circulation flow path 8 (see FIG. 5) to the head 1a and the head 1b arranged in this way, the ink flow direction (arrow A in the figure) in the manifold 101 of the head 1a is in the first direction. 6 from left to right in FIG. 6, and the direction of ink flow (arrow B in the figure) in the manifold 101 of the head 1b is from right to left in FIG. 6 along the first direction, which are opposite to each other. .

The manifold 101 of the head 1a and the head 1b is provided with a plurality of individual flow paths (see FIGS. 3 and 4) such as the pressure generation chamber 12 along the first direction. Since ink flows into each individual flow path from the manifold 101, the ink pressure is higher on the upstream side (first opening 44 side) of the manifold 101, and the ink pressure is lower on the downstream side (second opening 45 side).
That is, an ink pressure gradient is generated from the upstream side toward the downstream side.

Here, as shown in FIG. 6B, in this embodiment, the head unit II (see FIG. 1).
The nozzle rows 21A of the head 1a and the head 1b held in the same pitch are set to the same pitch.
That is, for each nozzle row 21A of the heads 1a and 1b, the i-th nozzle 21 counting from the left (where N is the number of nozzles in the nozzle row 21A and i is an integer from 1 to N) In the same position. By controlling the ejection timing of each head 1a and head 1b, each ink droplet ejected from the head 1a and each ink droplet ejected from the head 1b can be landed at the same location.

FIG. 6C shows ink droplets ejected by the head 1a and the head 1b. The ink droplet Ai (i is an integer from 1 to N) represents an ink droplet ejected from the i-th nozzle 21 counted from the left of the head 1a. Similarly, an ink droplet Bi (i is an integer from 1 to N) represents an ink droplet ejected from the i-th nozzle 21 counted from the left of the head 1a.

In each head 1a and head 1b, due to the ink pressure gradient generated in the manifold 101, the ink droplet Ai ejected by the head 1a is larger on the upstream side (left side in the figure) and smaller on the downstream side (right side in the figure). . On the other hand, the ink droplets Bi ejected by the head 1b are larger on the upstream side (right side in the figure) and smaller on the downstream side (left side in the figure). In the figure, in order to make the difference in the size of the ink droplets easy to understand, the difference is deliberately expressed. In fact, there is no difference as much as the ink droplets in the drawing.

If the ink is ejected onto the recording sheet S by the head 1a or the head 1b alone,
Such a difference in the size of the ink droplets appears as a density gradient in which the ink is dark in the region facing the upstream side and thin in the region facing the downstream side.

As shown in FIG. 6D, when the head 1a and the head 1b having such a configuration discharge ink, the ink droplet Ai and the ink droplet Bi form one ink droplet Ci.

Each ink droplet Ci thus formed is an ink droplet having a uniform size and shape. For example, since the ink droplet A1 of the head 1a is on the upstream side of the manifold 101, it has a relatively large shape. The ink droplet B1 of the head 1b corresponding to this corresponds to the manifold 101.
Since it is on the downstream side, the shape is relatively small. The next ink droplet A2 is slightly smaller than the ink droplet A1, and the ink droplet B2 is accordingly slightly larger than the ink droplet B1. Or later,
Similarly, the ink droplet Ai is reduced, while the ink droplet Bi is increased. Thus, since the size of the ink droplet Bi increases in response to the decrease in the size of the ink droplet Ai, each ink droplet Ci synthesized from the ink droplet Ai and the ink droplet Bi has an equal shape. Become.

As described above, in the ink jet recording apparatus I according to the present embodiment, the ink flow directions in the manifold 101 of the pair of heads 1a and 1b are opposite to each other. Thereby, the density gradient of the ink ejected from one head 1a and the density gradient of the ink ejected from the other head 1b are opposite to each other, and the entire ink ejected by the pair of the head 1a and the head 1b is as follows. The concentration is equal. In this way, in the ink jet recording apparatus I according to the present embodiment, the ink can be circulated by the circulation flow path 8 and high-quality printing can be performed while preventing unevenness of the ink density.

In the above-described example, the nozzle rows 21A of the head 1a and the head 1b have the same pitch. However, the present invention is not limited to such a mode.

FIG. 7A is a plan view schematically showing a manifold of a pair of heads according to a modification, and FIG. 7B is a plan view schematically showing a nozzle of a pair of heads according to the modification. Figure
FIG. 7C is a plan view schematically showing ink droplets ejected from a pair of heads according to a modification. The same components as those shown in FIG. 6 are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 7B, the nozzle rows 21A of the head 1a and the head 1b held by the head unit II (see FIG. 1) according to the modification are shifted by a half pitch. That is, the i-th nozzle 21 of the head 1b is disposed between the i-th and i + 1-th nozzles 21 of the head 1a (the N-th nozzle 21 of the head 1b is located outside the N-th of the head 1a). Is placed).

As shown in FIG. 7C, when the head 1a and the head 1b having such a configuration eject ink, ink droplets Ai and ink droplets Bi appear alternately. Also in this case, since the density gradient of the ink ejected from one head 1a and the density gradient of the ink ejected from the other head 1b are opposite to each other, a pair of the ink droplet Ai and the ink droplet Bi. The area occupied by
Each group is almost evenly aligned. As a result, the entire ink ejected by the pair of the head 1a and the head 1b has a uniform density. In this way, in the ink jet recording apparatus I in which the nozzle row 21A is shifted by a half pitch, the ink is circulated by the circulation flow path 8, and the ink density unevenness is prevented and high-quality and high-density printing is performed. Can do.

<Embodiment 2>
In this embodiment, the aspect of the circulation flow path 8 is illustrated. 8 to 10 are schematic diagrams illustrating the configuration of the circulation flow path according to the second embodiment.

As shown in FIG. 8A, as in the first embodiment, the first opening 44 and the second opening 45 of the head 1a, and the first opening 44 and the second opening 45 of the head 1b are opposite to each other. Are arranged as follows. The supply pipe 6 is connected from the ink tank 5 to the first opening 44 of the head 1a, and the recovery pipe 7 is connected to the ink tank 5 from the second opening 45 of the head 1b. Further, the connecting pipe 9 is connected from the second opening 45 of the head 1a to the first opening 44 of the head 1b.
The connecting tube 9 also functions as the supply tube 6 and the recovery tube 7 and supplies the ink recovered from the second opening 45 of the head 1a to the first opening 44 of the head 1b. Such a supply pipe 6
A circulation channel 8 is constituted by the recovery pipe 7 and the connecting pipe 9.

FIG. 8B has a plurality of pairs of heads 1a and 1b (two in the example shown in the figure), and one circulation channel 8 is provided for each pair. That is, it has a plurality of configurations of the circulation flow path 8 and the pair of heads 1a and 1b in FIG.

8A and 8B, one circulation channel 8 is provided for the pair of heads 1a and 1b, and this circulation channel 8 is connected in series from the head 1a to the head 1b. In particular, the ink is supplied and recovered.

8A and 8B, since the ink flow direction A and the flow direction B in the pair of heads 1a and 1b are opposite to each other, the concentration gradient due to the pressure gradient is prevented. High-quality printing can be performed. In addition, since one circulation channel 8 is provided for the pair of heads 1a and 1b, the pressure loss that may occur in the other pair of heads 1a and 1b is not affected.

FIG. 8C has a plurality of (two in the example of the figure) a pair of heads 1a and 1b, and one circulation channel is provided for these. Specifically, the supply pipe 6 is connected from the ink tank 5 to the first opening 44 of one head 1a, and the recovery pipe 7 is connected to the ink tank 5 from the second opening 45 of one head 1b. Connect the remaining first opening 44 and second opening 45 to the connecting pipe 9.
The circulation flow path 8 is configured by connecting them with each other.

In this embodiment, one circulation channel 8 is provided for every pair of heads 1a and 1b, and this circulation channel 8 is configured to supply and collect ink in series from the head 1a to the head 1b. Yes. Also, the ink flow direction A in the pair of heads 1a and 1b.
Since the flow direction B is opposite, high-quality printing in which a concentration gradient due to a pressure gradient is prevented can be performed. Furthermore, since one circulation channel 8 is provided for every pair of heads 1a and 1b, the number of members constituting the circulation channel 8 such as the pump P can be reduced.

As shown in FIG. 9A, as in the first embodiment, the first opening 44 and the second opening 45 of the head 1a, and the first opening 44 and the second opening 45 of the head 1b are opposite to each other. Are arranged as follows. A supply branch pipe 62 constituting the supply pipe 6 is connected from the ink tank 5 to the first openings 44 of the head 1a and the head 1b. Similarly, the collection branch pipe 72 constituting the collection pipe 7 is connected to the ink tank 5 through the second opening 45 of the head 1a and the head 1b.

In FIG. 9B, there are a plurality of (two in the example in the figure) a pair of heads 1a and 1b.
An ink jet recording apparatus is shown in which the circulation channel 8 having the configuration shown in FIG. 9A is provided for each pair. That is, it has a plurality of configurations of the circulation flow path 8 and the pair of heads 1a and 1b in FIG.

9A and 9B, the ink jet recording apparatus of any of the modes is provided with one circulation channel 8 for the pair of heads 1a and 1b, and this circulation channel 8 is connected to the head 1a. The ink is supplied to and recovered from the head 1b in parallel.

9A and 9B, the ink flow direction A and the flow direction B of the pair of heads 1a and 1b are opposite to each other. It is possible to perform high-quality printing in which the density gradient due to is prevented. In addition, since one circulation channel 8 is provided for the pair of heads 1a and 1b, the pressure loss that may occur in the other pair of heads 1a and 1b is not affected.

FIG. 9 (c) has a plurality of pairs of heads 1a and 1b (two in the example in the figure),
For these, an ink jet recording apparatus provided with one circulation channel is shown. Specifically, a supply branch pipe 62 constituting the supply pipe 6 is connected from the ink tank 5 to the first opening 44 of each head 1a. Similarly, a collection branch pipe 72 constituting the collection pipe 7 is connected to the ink tank 5 from the second opening 45 of each head 1b.

In this embodiment, one circulation channel 8 is provided for every pair of heads 1a and 1b, and this circulation channel 8 supplies ink to each head 1a in parallel, and from each head 1b in parallel. The ink is collected. Further, since the ink flow direction A and the flow direction B in the pair of heads 1a and 1b are opposite to each other, high-quality printing in which a density gradient due to a pressure gradient is prevented can be performed. Furthermore, all the pairs of heads 1a and 1
Since one circulation channel 8 is provided for b, the number of members constituting the circulation channel 8 such as the pump P can be reduced.

Further, as shown in FIG. 10, a plurality of (two in the figure) a pair of heads 1a and 1b are provided, and one circulation channel 8 is provided for each head 1a and one circulation channel 8 is provided for each head 1b. Also good. That is, one circulation channel 8 is provided for the head 1a whose flow direction in the manifold 101 is the same direction, and similarly, one circulation channel 8 is provided for the head 1b whose flow direction in the manifold 101 is the same direction.

In each pair of heads 1a and 1b, as in the first embodiment, the first opening 44 and the second opening 45 of the head 1a and the first opening 44 and the second opening 45 of the head 1b are opposite to each other. Are arranged as follows.

For the two heads 1a, the supply pipe 6 is connected from the ink tank 5 to the first opening 44 of one head 1a. The collection tube 7 is connected to the ink tank 5 through the second opening 45 of the other head 1a. Furthermore, the connecting pipe 9 is connected from the second opening 45 of one head 1a to the first opening 44 of the other head 1a.

The same applies to the two heads 1b. That is, the supply pipe 6 is connected from the ink tank 5 to the first opening 44 of one head 1b. Further, the recovery pipe 7 is connected to the other head 1.
The ink tank 5 is connected to the second opening 45 of b. Further, the connecting pipe 9 is connected from the second opening 45 of one head 1b to the first opening 44 of the other head 1b.

Thus, one circulation channel 8 is connected to each head 1a, and the other circulation channel 8 is connected to each head 1.
Ink is supplied and recovered in series between b. Incidentally, Embodiment 1
The two circulation flow paths 8 shown in FIG. 5 are configured to supply and collect ink in parallel between the heads 1a and between the heads 1b, respectively.

Also in the aspect of this aspect, the ink flow direction A in the pair of heads 1a and 1b.
Since the flow direction B is opposite, high-quality printing in which a concentration gradient due to a pressure gradient is prevented can be performed. In addition, since one circulation channel 8 is provided for each of the head 1a and the head 1b, it is possible to prevent the pressure loss that may occur in the head 1a and the head 1b from affecting the other head 1b and the head 1a.

<Other embodiments>
In the embodiment described above, the two heads 1 are arranged in the second direction, but this is not a limitation. It is sufficient that at least two or more heads 1 are arranged in parallel. Even number of heads 1
Are juxtaposed in the second direction, any two become a pair of heads 1a and 1b. The pair of heads 1a and 1b arranged side by side may be adjacent to each other or may be separated with another head interposed therebetween. Further, when the odd number of heads 1 are juxtaposed in the second direction, the ink flow direction is reversed between the even number of heads 1 juxtaposed in the second direction. Thereby, since the density gradient is eliminated in the even number of heads 1, the influence of the density gradient by the remaining one head 1 can be reduced.

The ink tank 5 may be provided with a heating means for heating the stored ink. By heating the ink, the viscosity of the ink is lowered and the ink can be circulated well.

Further, as the pressure generating means, the first electrode 60, the piezoelectric layer 70 made of a piezoelectric material, and the second
Although the thin film type piezoelectric element 300 in which the electrode 80 is formed by film formation and lithography is used, the present invention is not limited to this.

For example, it may be a longitudinal vibration type piezoelectric element in which piezoelectric materials and electrode forming materials are alternately stacked to expand and contract in the axial direction. Alternatively, a lateral vibration type piezoelectric element in which piezoelectric materials and electrode forming materials are alternately stacked and one end portion in the stacking direction is in contact with the vibration plate may be used. further,
A thick film type piezoelectric element formed by a method such as attaching a green sheet can also be used. Also, as a pressure generating means, a heating element is arranged in the pressure generating chamber, and droplets are discharged from the nozzle opening by bubbles generated by the heat generated by the heating element, or static electricity is generated between the diaphragm and the electrode. In addition, it is possible to use a device in which a diaphragm is deformed by electrostatic force and droplets are ejected from a nozzle opening.

In the above-described embodiment, the line type ink jet recording apparatus in which each head is fixed is shown. However, the present invention can also be used for a so-called serial type ink jet recording apparatus. Note that the serial ink jet recording apparatus is a device that performs printing while moving the liquid ejecting head in a direction intersecting the transport direction of the recording medium. Further, in the above-described embodiment, the one having eight heads is shown, but this number is not limited, and for example, one having one head may be used.

Further, in the above-described embodiment, the present invention has been described by exemplifying the head 1 that ejects ink droplets. However, the present invention is intended for a wide range of liquid ejecting heads in general. Examples of the liquid ejecting head include a recording head used for an image recording apparatus such as a printer, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an organic EL display, and an FE.
Electrode material ejection head used for electrode formation for D (field emission display), bio-ch
Examples thereof include bioorganic matter ejecting heads used for ip production.

I ink jet recording apparatus (liquid ejecting apparatus), II head unit, 1, 1
a, 1b head (liquid ejecting head), 5 ink tank, 6 supply pipe, 7 recovery pipe, 8 circulation flow path, 9 connection pipe, 12 pressure generating chamber, 20 nozzle plate,
21 nozzle, 21A nozzle row, 44 first opening, 45 second opening, 61 supply trunk, 62 supply branch, 71 recovery trunk, 72 recovery branch, 100 head main body, 101 manifold (common flow path), 170 Channel member, 300 Piezoelectric element

Claims (6)

Nozzle rows in which nozzles for discharging liquid are arranged in the first direction, individual flow paths having pressure generation chambers communicating with the nozzles, common flow paths communicating with the individual flow paths, and pressure changes in the pressure generation chambers A liquid jet head having pressure generating means for generating;
A supply path for supplying liquid from outside to the common flow path and a circulation flow path including a recovery path for recovering liquid from the common flow path to the outside;
The liquid ejecting apparatus, wherein the liquid ejecting heads are arranged side by side in a second direction intersecting the first direction so that a flow direction of the liquid in the common flow path of the liquid ejecting heads is opposite. The liquid ejecting apparatus according to claim 1,
The liquid ejecting heads arranged in parallel so that the liquid flow directions in the common flow path are opposite to each other are aligned in the first direction of each nozzle. The liquid ejecting apparatus according to claim 1,
In the liquid ejecting heads arranged in parallel so that the liquid flow direction in the common flow path is reversed, each nozzle in the first direction of one liquid ejecting head is the first of the other second liquid ejecting head. The liquid ejecting apparatus is located between the nozzles in the direction. In the liquid ejecting apparatus according to any one of claims 1 to 3,
The liquid ejecting apparatus, wherein the circulation flow path is provided for each of the liquid ejecting heads arranged in parallel so that the liquid flow direction in the common flow path is opposite. In the liquid ejecting apparatus according to any one of claims 1 to 3,
The liquid ejecting apparatus is characterized in that the circulation channel is provided in common to a plurality of liquid ejecting heads. In the liquid ejecting apparatus according to any one of claims 1 to 3,
A plurality of the liquid jet heads;
The liquid ejecting apparatus, wherein the circulation flow path is provided for each liquid ejecting head in which the liquid flow direction in the common flow path is the same.

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