JP2012143956A - Line head, method for manufacturing the same, and recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line head, a method for manufacturing the same, and recording device, capable of improving the printing quality without variation of a position and direction where ink is discharged.SOLUTION: The line head includes: a base plate 21 having a plurality of first nozzle holes 23; and a nozzle unit 22 having a second nozzle 25 and an actuator, the second nozzle being arranged on the base plate 21 and communicating to the first nozzle 23, the actuator being disposed at each of the second nozzle hole 25.

Description

  The present invention relates to a line head, a method for manufacturing a line head, and a recording apparatus.

  One of the recording apparatuses described above is an ink jet recording apparatus. As an ink jet recording apparatus, an apparatus using a head unit in which nozzle holes are arranged over the entire width of printing has been proposed instead of a system in which a nozzle head moves because of a demand for higher printing speed.

  Therefore, a line head that can cover the entire width of the print medium is required. However, since it is difficult to integrally form such a long line head, for example, as described in Patent Documents 1 to 3 It is known that a line head is configured by arranging a plurality of relatively small nozzle heads in combination.

Japanese Patent Laid-Open No. 11-34360 Japanese Patent No. 3302785 JP 2004-322606 A

  However, if the alignment of the plurality of nozzle heads is not good, the position and direction of ink ejection varies among the nozzles, and for example, streaky print unevenness may occur in the printed matter. In addition, if pressure is applied or heat is applied after aligning a plurality of nozzle heads, there is a problem that the position of the nozzle heads is shifted. That is, there is a problem that it is difficult to align the positions of the plurality of nozzle heads with high accuracy.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A line head according to this application example includes a first substrate having a plurality of first nozzle holes and a plurality of first heads arranged on the first substrate, and corresponding first of the plurality of first nozzle holes. And a nozzle unit having a second nozzle hole communicating with the nozzle hole and an actuator provided for each second nozzle hole.

  According to this configuration, when the nozzle unit is disposed on the first substrate, the nozzle unit is arranged so that the second nozzle hole communicates with the first nozzle hole with reference to the first nozzle hole provided in the first substrate. Since positioning is sufficient, high accuracy is not required in positioning the nozzle unit. In other words, if the positional accuracy of the first nozzle holes in the first substrate is ensured, a line head capable of ejecting ink or the like with high positional accuracy can be provided regardless of the positional accuracy of the nozzle unit.

  Application Example 2 In the line head according to the application example described above, it is preferable that a diameter of the second nozzle hole is larger than a diameter of the first nozzle hole in a portion where the first substrate and the nozzle unit are in contact with each other.

  According to this configuration, since the diameter of the second nozzle hole is larger than the diameter of the first nozzle hole, it is possible to allow positional deviation when the nozzle unit is arranged on the first substrate. In other words, even when the position of the second nozzle hole is deviated from the normal position, for example, the liquid can be sent from the second nozzle hole to the first nozzle hole.

  Application Example 3 In the line head according to the application example described above, it is preferable that the nozzle unit is provided for each nozzle row including the plurality of first nozzle holes in the first substrate.

  According to this configuration, since one nozzle unit is arranged with the nozzle row as one unit, the position of the plurality of second nozzle holes is highly accurately set to the position of the plurality of first nozzle holes by one alignment. Can be adapted to

  Application Example 4 In the line head according to the application example described above, it is preferable that a plurality of the nozzle arrays are arranged on the first substrate in parallel so as to be inclined with respect to the first direction.

  According to this configuration, the first nozzle holes that contribute to printing by arranging the nozzle row including the plurality of first nozzle holes, for example, so as to be inclined with respect to the conveyance direction (first direction) of the printing paper. Can be narrowed. That is, a line head capable of ejecting ink with high definition can be provided.

  Application Example 5 A method of manufacturing a line head according to this application example includes a first nozzle hole forming step of forming a plurality of first nozzle holes in a first substrate using a photolithography method, and the plurality of first nozzles. A second nozzle hole forming step for forming a plurality of second nozzle holes in the second substrate communicating with the corresponding first nozzle holes, and an actuator for the second substrate corresponding to each second nozzle hole. A nozzle unit forming step of forming a nozzle unit, and a bonding step of bonding the first substrate and the nozzle unit by anodic bonding.

  According to this method, when the first substrate and the nozzle unit are joined, the position of the first nozzle hole of the first substrate formed by using the photolithography method serves as a reference for the discharge position. The positional accuracy between the first nozzle holes can be improved as compared with the case of mutual alignment.

  Application Example 6 In the line head manufacturing method according to the application example described above, it is preferable that the joining step uses a part of the plurality of first nozzle holes as an alignment mark of the first substrate.

  According to this method, by using a part of the first nozzle hole, it is possible to perform alignment between the first substrate and the nozzle unit without forming a dedicated alignment mark.

  Application Example 7 A recording apparatus according to this application example includes the line head described above.

  According to this configuration, since the above-described line head is provided, it is possible to provide a recording apparatus that can improve the positional accuracy between the nozzles, increase the printing speed, and improve the printing quality. .

FIG. 3 is a schematic diagram illustrating a configuration of a liquid ejection apparatus as a recording apparatus including a line head. It is a schematic plan view which shows the structure of a line head, (a) is a schematic plan view which shows the state which combined the base plate and the nozzle unit, (b) is a schematic plan view which shows the structure of a base plate, (c) is a nozzle unit. The schematic plan view which shows the structure. FIG. 3 is an enlarged perspective view schematically showing a structure of an A part of the line head shown in FIG. 2. FIG. 4 is a schematic cross-sectional view along the line BB ′ of the line head shown in FIG. 3. It is a schematic diagram which shows the manufacturing method of a line head, (a) is a schematic plan view, (b) is a schematic cross section. It is a schematic diagram which shows the manufacturing method of a line head, (a) is a schematic plan view, (b) is a schematic cross section. It is a schematic diagram which shows the manufacturing method of a line head, (a) is a schematic plan view, (b) is a schematic cross section. It is a schematic diagram which shows the manufacturing method of a line head, (a) is a schematic plan view, (b) is a schematic cross section. The schematic plan view which shows the modification of arrangement | positioning of a nozzle unit. The schematic plan view which shows the modification of arrangement | positioning of a nozzle unit. The schematic plan view which shows the modification of arrangement | positioning of a nozzle unit.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. Note that the drawings to be used are appropriately enlarged or reduced so that the part to be described can be recognized.

<Configuration of recording apparatus>
FIG. 1 is a schematic diagram illustrating a configuration of a liquid ejection apparatus (inkjet recording apparatus) as a recording apparatus including a line head. Hereinafter, the configuration of the liquid ejection apparatus will be described with reference to FIG.

  As shown in FIG. 1, the liquid ejection apparatus 10 includes a transport roller 13 that transports the recording paper 11 onto the platen 12, a step motor 14 that rotationally drives the transport roller 13, and a guide rail 15. The line head 20 that ejects ink droplets onto the recording paper 11 that is mounted and movably mounted in a direction perpendicular to the (first direction), and the line head 20 vibrates in a direction perpendicular to the conveyance direction of the recording paper 11. The vibration element 30 (refer FIG. 3, FIG. 4) to be made to have and the controller 40 which controls the whole apparatus are provided.

  The vibration element 30 is formed of, for example, a piezoelectric element (electrostrictive vibrator) such as PZT, and is attached to the line head 20. Therefore, by vibrating the vibration element 30, the line head 20 can be vibrated in a direction perpendicular to the conveyance direction of the recording paper 11 along the guide rail 15.

  The controller 40 is configured as a microprocessor centered on the CPU 41. In addition to the CPU 41, a ROM 42 for storing various processing programs, a RAM 43 for temporarily storing data, and a flash memory 44 capable of writing and erasing data. An interface (I / F) 45 for exchanging information with an external device, and an input / output port (not shown).

  The RAM 43 is provided with a print buffer area, and print data received from the user PC 46 via the interface (I / F) 45 can be stored in the print buffer area. Various operation signals from the operation panel 47 are input to the controller 40 via an input port. From the controller 40, a drive signal to the line head 20, a drive signal to the step motor 14, and the operation panel 47 are input. Output signals are output through the output port.

  The operation panel 47 is a device for inputting various instructions from the user and displaying and outputting the state. Although not shown, the operation panel 47 is a display or a user that displays characters, figures, or symbols corresponding to the various instructions. Are provided with buttons for performing various operations.

<Configuration of line head>
FIG. 2 is a schematic plan view showing the structure of the line head. FIG. 2A is a schematic plan view showing a state in which a base plate as a first substrate and a nozzle unit are combined. FIG. 2B is a schematic plan view showing the structure of the base plate. FIG. 2C is a schematic plan view showing the structure of the nozzle unit. Hereinafter, the structure of the line head will be described with reference to FIGS. 2 (a) to 2 (c). In the present embodiment, for example, the arrangement of nozzles in the case of using three colors of ink is shown.

  As shown in FIG. 2, the line head 20 includes a base plate 21 and a plurality of nozzle units 22 fixed side by side on the base plate 21.

  Examples of the base plate 21 include a transparent substrate such as glass. A plurality of first nozzle holes 23 for discharging ink are formed in the base plate 21. Specifically, a plurality of nozzle rows including a plurality of first nozzle holes 23 are provided in parallel so as to be inclined with respect to the transport direction which is the first direction. Furthermore, the base plate 21 is formed with alignment marks 24 used when a plurality of nozzle units 22 are joined.

  The first nozzle hole 23 and the alignment mark 24 are formed in the base plate 21 by using a photolithography method and an etching method. By using the photolithography method, the positional accuracy of the first nozzle hole 23 and the alignment mark 24 can be improved. Specifically, for example, the position accuracy can be suppressed to 0.5 μm or less.

  The nozzle unit 22 ejects ink and is arranged for each nozzle row. Further, the nozzle unit 22 has a nozzle unit plate 26 (see FIGS. 3 and 4) as a second substrate in which a plurality of second nozzle holes 25 which are portions for ejecting ink are formed. The nozzle unit plate 26 is, for example, a silicon substrate or a glass substrate.

  When the nozzle unit 22 is joined to the base plate 21, the second nozzle hole 25 and the first nozzle hole 23 communicate with each other. The nozzle unit 22 is formed with an alignment mark 27 used when the nozzle unit 22 and the base plate 21 are joined.

  By arranging a plurality of such nozzle units 22 on the base plate 21, the nozzle holes 23 and 25 are arranged over the entire width of the recording paper 11. The line head 20 enables high-quality printing by arranging the alignment mark 27 of the nozzle unit 22 with the alignment mark 24 of the base plate 21 as a reference.

  FIG. 3 is an enlarged perspective view schematically showing the structure of part A of the line head shown in FIG. FIG. 4 is a schematic cross-sectional view taken along line BB ′ of the line head shown in FIG. Hereinafter, the structure of the line head will be described with reference to FIGS.

  The line head 20 shown in FIGS. 3 and 4 is a diagram showing the structure of the line head 20 corresponding to one of the colors such as cyan (C), magenta (M), yellow (Y), and black (K). is there. The structure of the line head 20 corresponding to other colors is the same.

  The nozzle unit 22 constituting the line head 20 includes a nozzle unit plate 26 and an actuator 22a. The actuator 22 a has a diaphragm 31 and a partition wall 32, and the partition wall 32 is sandwiched between the nozzle unit plate 26 and the diaphragm 31. Further, the actuator 22a includes an ink pressure chamber 33 that communicates with each of the second nozzle holes 25, and has a structure for changing the pressure of each ink pressure chamber 33 using a piezoelectric element (vibration element 30) and discharging ink. Have. The ink pressure chambers 33 are connected to each other via a large-capacity common ink chamber 34, and the common ink chamber 34 has a structure in which ink is supplied from an ink supply source (not shown). .

  In the upper part of the nozzle unit 22, for example, an ink cartridge 35 (individually containing cyan (C), magenta (M), yellow (Y), and black (K) inks containing a dye or pigment in a solvent. 1) is arranged. Ink droplets 36 corresponding to the respective color inks supplied from the ink cartridge 35 can be ejected from the second nozzle hole 25 through the first nozzle hole 23.

  In addition, as a method for ejecting the ink droplets 36 from the line head 20, a piezoelectric method in which the piezoelectric elements (piezo elements) are deformed by ejecting the ink droplets 36 by applying a voltage to the piezoelectric elements (piezo elements), or a heater or the like generates heat. It is possible to use a thermal ink jet method in which bubbles are generated by applying a voltage to the resistor to heat the ink, and the ink is pressurized by the bubbles to eject the ink droplets 36.

  The plurality of first nozzle holes 23 of each base plate 21 are, for example, formed in a straight line with an interval (pitch) of 0.2 mm, and the distance between the right end and the left end of the first nozzle holes 23 is recorded. It is slightly larger than the width of the paper 11. A first electrode 37, a piezo element 38, and a second electrode 39 are stacked on the upper side of each ink pressure chamber 33 across the diaphragm 31.

  As shown in FIG. 4, the cross-sectional shape of the first nozzle hole 23 of the base plate 21 is, for example, two-stage tapered holes 23a and 23b having different inclinations. The diameter of the second nozzle hole 25 communicating with the first nozzle hole 23 is larger than the diameter of the first nozzle hole 23.

  As described above, when the base plate 21 and the nozzle unit 22 are combined by forming the first nozzle hole 23 with a normal hole diameter for ejecting ink and setting the second nozzle hole 25 larger than the first nozzle hole 23. Misalignment (alignment accuracy) can be allowed, and it is possible to suppress an influence on a change in the discharge amount.

  In the vicinity of the vibration plate 31, a hole 51 connected to the ink cartridge 35 is provided. When ink is supplied from an ink pack (not shown) of each color of the ink cartridge 35 to the common ink chamber 34 through the hole 51 and then a voltage is applied to the piezo element 38 from both electrodes 37 and 39, the piezo element 38. The internal pressure of the ink pressure chamber 33 is changed by the vibration of the vibration plate 31 due to the expansion and contraction of the ink, and the ink stored in the ink pressure chamber 33 is ejected as ink droplets 36 from the nozzle holes 23 and 25.

<Production method of line head>
5 to 8 are schematic views showing the method of manufacturing the line head in the order of steps. (A) is a schematic plan view which shows the manufacturing method of a line head. (B) is a schematic cross-sectional view along the line CC ′ of the line head shown in (a). Hereinafter, the manufacturing method of the line head will be described with reference to FIGS.

  First, as shown in FIG. 5, a precursor plate 21 a to be a base plate 21 is prepared. Examples of the precursor plate 21a include a glass substrate that is a transparent substrate. Moreover, as a thing other than a glass substrate, a thing with a suitable thermal expansion coefficient is preferable, for example, resin and a silicon-type material may be sufficient. The definition of transparency is acceptable as long as it is an area that can be discriminated in the apparatus structure other than the visible light area.

  Next, as shown in FIG. 6, a portion other than the edge of the precursor plate 21 a is formed in the thickness of the base plate 21. Specifically, for example, the precursor plate 21a is etched using an etchant such as hydrofluoric acid. Further, as a method other than etching, the base plate 21 may be formed to have a thickness by machining.

  As a result, the edge of the precursor plate 21 b remains as it is as the raw material, and the thickness of the other portions is reduced to the thickness of the base plate 21. As a result, it is possible to suppress the strength of the precursor plate 21b from being significantly reduced. The thickness of the thinned base plate 21 is, for example, about 60 μm to 70 μm.

  Next, as shown in FIG. 7, the first nozzle hole 23 is formed in the dug portion of the precursor plate 21b (see FIG. 6) (first nozzle hole forming step). First, a first resist pattern having a first opening hole is formed in a portion that becomes the first-stage tapered hole 23a (discharge side) of the first nozzle hole 23 by using a photolithography technique. Next, isotropic dry etching is performed using the first resist pattern as a mask. As a result, a first-stage tapered hole 23a is formed. The diameter of the discharge port of the tapered hole 23a is, for example, 20 μm.

  Next, the first resist pattern is removed, and a second resist pattern having a second opening hole is formed using a photolithography technique in a portion that becomes the second-stage tapered hole 23b using a photolithography technique. (First nozzle hole forming step). Then, isotropic dry etching is performed using the second resist pattern as a mask. The first opening hole and the second opening hole have different etching rates, whereby the first nozzle hole 23 having two-step tapered holes 23a and 23b is formed.

  As described above, by forming the first nozzle holes 23 of the base plate 21 using the photolithography technique, the positional accuracy between the first nozzle holes 23 can be improved. Thereafter, the second nozzle hole 25 is formed in the nozzle unit plate 26 constituting the nozzle unit 22 (second nozzle hole forming step), and the nozzle unit plate 26 and the actuator 22a are combined (nozzle unit forming step).

  Next, as shown in FIG. 8, the base plate 21 and the nozzle unit 22 are anodically bonded (bonding step). First, mutual alignment is performed with reference to the alignment marks 24 and 27 formed on the base plate 21 and the nozzle unit 22.

  Specifically, the position of the alignment mark 27 formed on the nozzle unit 22 matches with the position of the alignment mark 24 formed on the base plate 21 as a reference, for example, a CCD camera or a microscope via the nozzle unit 22. Alignment is performed while checking using the optical system.

  The base plate 21 and the nozzle unit 22 may be automatically aligned by performing image processing on the captured images of the alignment marks 24 and 27 using a CCD camera.

  Next, the aligned base plate 21 and nozzle unit 22 are heated to, for example, 380 ° C., the nozzle unit 22 is connected to the anode, the base plate 21 is connected to the cathode, and anodic bonding is performed by applying a voltage of 800V. .

  Thereby, the 1st nozzle hole 23 and the 2nd nozzle hole 25 are connected, and the nozzle holes 23 and 25 are formed. In addition, by setting the diameter of the second nozzle hole 25 to be larger than the diameter of the first nozzle hole 23, positional deviation (alignment accuracy) when the base plate 21 and the nozzle unit 22 are combined can be allowed, and the discharge amount and the like It is possible to suppress the influence on the change.

  As described above in detail, according to the line head 20, the manufacturing method of the line head 20, and the recording apparatus, the following effects can be obtained.

  (1) According to the line head 20 of the present embodiment, when the nozzle unit 22 is disposed on the base plate 21, the second nozzle is placed in the first nozzle hole 23 with reference to the first nozzle hole 23 provided in the base plate 21. Since the nozzle unit 22 only needs to be positioned so that the holes 25 communicate with each other, high accuracy is not required in positioning the nozzle unit 22. In other words, if the positional accuracy of the first nozzle holes 23 in the base plate 21 is ensured, the line head 20 that can eject the ink droplets 36 with high positional accuracy regardless of the positional accuracy of the nozzle unit 22 can be provided.

  (2) According to the line head 20 of the present embodiment, since the hole diameter of the second nozzle hole 25 is larger than the hole diameter of the first nozzle hole 23, the positional deviation when the nozzle unit 22 is arranged on the base plate 21 is allowed. be able to. In other words, even when the position of the second nozzle hole 25 is deviated from the normal position, for example, ink can be sent from the second nozzle hole 25 to the first nozzle hole 23.

  (3) According to the manufacturing method of the line head 20 of the present embodiment, when the base plate 21 and the nozzle unit 22 are joined, the position of the first nozzle hole 23 of the base plate 21 formed using the photolithography method is discharged. Since the position is a reference, the positional accuracy between the first nozzle hole 23 and the first nozzle hole 23 can be improved as compared with the case where the nozzle holes are aligned between the nozzle units 22.

  (4) According to the recording apparatus of the present embodiment, since the above-described line head 20 is provided, the positional accuracy between the nozzles can be improved, the printing speed can be increased and the printing quality can be improved. A recording apparatus (liquid ejection apparatus 10) can be provided.

  In addition, embodiment is not limited above, It can also implement with the following forms.

(Modification 1)
As described above, the arrangement pattern of the nozzle units 22 with respect to the base plate 21 is not limited to the arrangement form as illustrated in FIG. 2, and may be the arrangement as illustrated in FIGS. 9 to 11, for example. 9 to 11 are schematic plan views showing modifications of the arrangement of the nozzle units 122 (122a, 122b), 222 (222a, 222b), and 322 (322a, 322b, 322c). The line head 110 shown in FIG. 9 is a pattern in which the nozzle units 122 in the case of two colors are arranged. Specifically, the two color nozzle units 122 a and 122 b are alternately arranged and are inclined with respect to the base plate 121. According to this, although the color reproducibility is lower than that of the line head 20 shown in FIG. 2, high-definition printing can be performed.

  The line head 210 shown in FIG. 10 is a pattern in which two color nozzle units 222 a and 222 b are arranged in parallel to the long side of the base plate 221. Specifically, the two color nozzle units 222a and 222b are alternately arranged. According to this, as compared with the line head 110 shown in FIG. 9 described above, the pitch interval between the nozzle holes 23 and 25 is widened and the definition is lowered, but the line can be saved with fewer nozzle units 222a and 222b. A head 210 can be provided.

  The line head 310 shown in FIG. 11 has a pattern in which three color nozzle units 322 a, 322 b, and 322 c are arranged in parallel to the long side of the base plate 321. Specifically, three color nozzle units 322a, 322b, and 322c are repeatedly arranged in order. According to this, the color reproducibility can be improved although the area is larger than the line head 210 shown in FIG. 10 described above.

(Modification 2)
As described above, the cross-sectional shape of the first nozzle hole is not limited to a two-step tapered shape (see FIG. 4), and may include a straight portion. For example, since the portion of the nozzle on the ink ejection side is straight, it is possible to stabilize the direction in which the ink flows, and the ink can be ejected to a target position. As a forming method, for example, the straight hole can be penetrated in the vertical direction by anisotropic etching, and then the tapered shape can be opened halfway by isotropic etching.

(Modification 3)
As described above, the method is not limited to the method of ejecting ink using a piezo element, and may be ejected using, for example, an electrostatic method, a thermal method, or other methods.

(Modification 4)
As described above, instead of forming the alignment marks 24 and 27 and aligning the base plate 21 and the nozzle unit 22, for example, a part of the first nozzle hole 23 or the second nozzle hole 25 may be aligned with the alignment mark. May be used to align each other. According to this, the formation process of the alignment marks 24 and 27 can be omitted.

  DESCRIPTION OF SYMBOLS 10 ... Liquid discharge apparatus, 11 ... Recording paper, 12 ... Platen, 13 ... Conveyance roller, 14 ... Step motor, 15 ... Guide rail, 20, 110, 210, 310 ... Line head, 21, 121, 221, 321 ... Base plate as one substrate, 21a, 21b ... precursor plate, 22, 122, 122a, 122b, 222a, 222b, 322a, 322b, 322c ... nozzle unit, 22a ... actuator, 23 ... first nozzle hole, 23a, 23b ... Tapered hole, 24 ... alignment mark, 25 ... second nozzle hole, 26 ... nozzle unit plate as second substrate, 27 ... alignment mark, 30 ... vibration element, 31 ... vibration plate, 32 ... partition, 33 ... ink pressure chamber 34 ... Common ink chamber, 35 ... Ink cartridge, 36 ... Ink 37 ... first electrode, 38 ... piezo element, 39 ... second electrode, 40 ... controller, 41 ... CPU, 42 ... ROM, 43 ... RAM, 44 ... flash memory, 45 ... interface, 46 ... user PC, 47 ... control panel.

Claims (7)

A first substrate having a plurality of first nozzle holes;
A plurality of nozzles arranged on the first substrate and having second nozzle holes communicating with corresponding first nozzle holes among the plurality of first nozzle holes, and an actuator provided for each of the second nozzle holes; Unit,
A line head comprising: The line head according to claim 1,
The line head, wherein a diameter of the second nozzle hole is larger than a diameter of the first nozzle hole in a portion where the first substrate and the nozzle unit are in contact with each other. The line head according to claim 1 or 2,
The line head according to claim 1, wherein the nozzle unit is provided for each nozzle row including the plurality of first nozzle holes in the first substrate. The line head according to claim 3,
A plurality of nozzle rows are arranged on the first substrate in parallel so as to be inclined with respect to the first direction. A first nozzle hole forming step of forming a plurality of first nozzle holes in the first substrate using a photolithography method;
A second nozzle hole forming step of forming a plurality of second nozzle holes in the second substrate communicating with corresponding first nozzle holes among the plurality of first nozzle holes;
A nozzle unit forming step of forming a nozzle unit by combining an actuator with the second substrate corresponding to each second nozzle hole;
A bonding step of bonding the first substrate and the nozzle unit by anodic bonding;
A method of manufacturing a line head, comprising: It is a manufacturing method of the line head according to claim 5,
In the bonding step, a part of the plurality of first nozzle holes is used as an alignment mark for the first substrate.   A recording apparatus comprising the line head according to claim 1.

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