Patent Application
20080068610
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Ink-jet recording head unit (liquid-jet head unit):
Prior to describing an alignment apparatus according to an embodiment of the invention, an explanation will be offered for an ink-jet recording head unit, as an example of a liquid-jet head unit, having an ink-jet recording head as an example of a liquid-jet head. The ink-jet recording head is an example of a workpiece which undergoes the alignment concerned.
As shown in these drawings, an ink-jet recording head unit 200 (to be referred to hereinafter as head unit 200) has a cartridge case 210, an ink-jet recording head 220, a cover head 240, and a fixing plate 250.
Of these members, the cartridge case 210 is a holding member for ink cartridges (not shown), which has a cartridge mounting portion 211 where the ink cartridges are mounted. The ink cartridges are ink supply means which are individually composed and, for example, filled with a black ink and three-color inks. That is, the cartridge case 210 is mounted with the ink cartridges of different colors.
As specified, particularly, in
The head case 230 is secured to the bottom surface of the cartridge case 210. The ink-jet recording head 220 has a plurality of piezoelectric elements 300, and ejects ink droplets through a nozzle orifice 21 at an end surface on a side opposite to the cartridge case 210 by driving of the piezoelectric element 300. A plurality of the ink-jet recording heads 220 are provided in correspondence with the different ink colors so as to eject the different colors of inks from the ink cartridges. Thus, a plurality of the head cases 230 are provided independently in correspondence with the ink-jet recording heads 220.
The above-described ink-jet recording head 220 and head case 230 will be described in further detail with additional reference to
As shown in
The nozzle plate 20 is secured to the opening surface side of the passage-forming substrate 10 via an adhesive agent, a heat-fused film or the like. The nozzle plate 20 has the nozzle orifices 21 each of which communicates with each pressure generating chamber 12 on a side opposite to the ink supply path 14. In the present embodiment, one ink-jet recording head 220 is provided with two nozzle rows 21A comprising two rows of the nozzle orifices 21 arranged parallel.
The nozzle plate 20 can be formed preferably from a glass-ceramics, a single crystal silicon substrate, or a stainless steel which has a thickness, for example, of 0.01 to 1 mm, and a coefficient of linear expansion, for example, of 2.5 to 4.5 (10−6/° C.) at 300° C. or lower. The nozzle plate 20 is provided with an alignment mark 22 (to be described in detail later) which is used for alignment with the fixing plate 250. In the present embodiment, two of the alignment marks 22 are provided at end portions in the parallel-arrangement direction of the nozzle orifices 21.
On the side of the passage-forming substrate 10 opposite from its opening surface, the piezoelectric elements 300 are disposed on the elastic film 50. The piezoelectric elements 300 are formed by sequentially stacking an insulation film 55 comprising zirconium oxide, a lower electrode film comprising a metal, a piezoelectric layer comprising lead zirconate titanate (PZT) or the like, and an upper electrode film comprising a metal.
The protective plate 30 is joined onto the passage-forming substrate 10 on which the piezoelectric elements 300 are formed. The reservoir portion 31, in the present embodiment, is formed to penetrate the protective plate 30 in its thickness direction and to extend in the width direction of the pressure generating chamber 12. As stated earlier, the reservoir portion 31 is brought into communication with the communicating portion 13 of the passage-forming substrate 10 to constitute the reservoir 100 serving as the common ink chamber for the pressure generating chambers 12. In a region of the protective plate 30 opposed to the piezoelectric element 300, a piezoelectric element holding portion 32 is provided which has space enough not to impede the movement of the piezoelectric element 300. Such a protective plate 30 can be suitably formed from glass, ceramic, metal, or plastic, but it is preferred to use a material having nearly the same thermal expansion coefficient as that of the passage-forming substrate 10. In the present embodiment, the protective plate 30 is formed using a single crystal silicon substrate which is the same material as that of the passage-forming substrate 10.
A drive IC 110 for driving each piezoelectric element 300 is provided on the protective plate 30. Each terminal of the drive IC 110 is connected to lead-out wiring withdrawn from an individual electrode of each piezoelectric element 300 via a bonding wire or the like (not shown). Each terminal of the drive IC 110 is connected to the outside via external wiring 111, such as a flexible printed cable (FPC), as shown in
The compliance plate 40 is joined onto the protective plate 30. In a region of the compliance plate 40 opposed to the reservoir 100, an ink introducing port 44 for supplying ink to the reservoir 100 is formed to penetrate the compliance plate 40 in its thickness direction. A region, other than the ink introducing port 44, in the region of the compliance plate 40 opposed to the reservoir 100 defines a flexible portion 43 formed thinly in the thickness direction. The reservoir 100 is sealed with the flexible portion 43. The flexible portion 43 imparts compliance to the interior of the reservoir 100. In more detail, the head case 230 having ink supply communicating paths 231 is provided on the compliance plate 40. In the head case 230, a depression 232 is formed in a region opposed to the flexible portion 43 so that flexible deformation of the flexible portion 43 takes place, as appropriate.
In the head case 230, a drive IC holding portion 233 penetrating the head case 230 in the thickness direction is provided in a region opposed to the drive IC 110 provided on the protective plate 30. The external wiring 111 is inserted through the drive IC holding portion 233, and connected to the drive IC 110.
With the ink-jet recording head 220 of the above-described configuration, ink from the ink cartridge is taken in through the ink introducing port 44 via the ink communicating path 212 (see
The respective members constituting the ink-jet recording head 220, and the head case 230 are provided with pin insertion holes 234, at two locations of corner portions thereof, for insertion of pins for positioning the respective members during assembly. By inserting the pins into the pin insertion holes 234 to position the respective members relatively, while joining the members to each other, the ink-jet recording head 220 and the head case 230 are integrally combined.
The above-mentioned ink-jet recording head 220 is formed by forming many chips simultaneously on a single silicon wafer, adhering them to the nozzle plate 20 and the compliance plate 40 to integrate these members, and then dividing the composite for each passage-forming substrate 10 of one chip size as shown in
Four of the ink-jet recording heads 220 and four of the head cases 230 are fixed to the cartridge case 210 with predetermined spacing in the direction of parallel arrangement of the nozzle rows 21A, as shown in
As described above, there are provided many of the nozzle rows 21A comprising rows of the nozzle orifices 21 arranged parallel using the plurality of the ink-jet recording heads 220. By so doing, a decrease in yield can be prevented in comparison with the formation of many of the nozzle rows 21A in the single ink-jet recording head 220. Furthermore, the plurality of ink-jet recording heads 220 are used to achieve the arrangement of the multiple nozzle rows 21A. By so doing, it becomes possible to increase the yield of the ink-jet recording heads 220 which can be formed from the single silicon wafer. This can narrow the wasteful region of the silicon wafer to cut down on the cost of production.
The above four ink-jet recording heads 220 are positioned and held by the fixing plate 250, which is the common fixing member joined to the ink droplet ejection surfaces of the plural ink-jet recording heads 220, as shown in
The joining portion 252 is composed of a fixing frame portion 253 provided along the outer periphery of the ink droplet ejection surfaces of the plural ink-jet recording heads 220, and a fixing beam portion 254 extending between the adjacent ink-jet recording heads 220 to divide the exposure opening portion 251. The joining portion 252 comprising the fixing frame portion 253 and the fixing beam portion 254 is joined altogether to the ink droplet ejection surfaces of the plural ink-jet recording heads 220. The fixing frame portion 253 of the joining portion 252 is formed to close the pin insertion holes 234 which position the respective members during manufacture of the ink-jet recording head 220.
The preferred material for the fixing plate 250 is, for example, a metal such as stainless steel, glass-ceramics, or a single crystal silicon substrate. For the fixing plate 250, it is preferred to use a material having the same thermal expansion coefficient as that of the nozzle plate 20 in order to prevent deformation due to the difference in thermal expansion from the nozzle plate 20. For example, when the nozzle plate 20 is formed from a single crystal silicon substrate, it is preferred to form the fixing plate 250 from a single crystal silicon substrate.
The fixing plate 250 is preferably formed thinly, desirably more thinly than the cover head 240 to be described later. If the fixing plate 250 is thick, ink is apt to remain, for example, between the ink droplet ejection surface of the nozzle plate 20 and the fixing beam portion 254 when the ink droplet ejection surface is wiped. However, the fixing plate 250 is formed thinly, whereby ink can be prevented from remaining on the ink droplet ejection surface of the nozzle plate 20 during wiping.
In the present embodiment, the thickness of the fixing plate 250 is set at 0.1 mm. The manner of joining between the fixing plate 250 and the nozzle plate 20 is not limited, and can be performed suitably, for example, using a thermosetting epoxy-based adhesive agent, or an ultraviolet curing adhesive agent.
As noted above, the fixing plate 250 closes the spaces between the adjacent ink-jet recording heads 220 by its fixing beam portion 254. Thus, ink does not enter the spaces between the adjacent ink-jet recording heads 220, and this can prevent ink-associated deterioration and destruction of the members of the ink-jet recording head 220, such as the piezoelectric element 300 and the drive IC 110. Moreover, the ink droplet ejection surface of the ink-jet recording head 220 and the fixing plate 250 are adhered together, without clearance, by the adhesive agent. Thus, the entry of a recording medium into the clearance, if any, can be prevented to prevent deformation of the fixing plate 250 and a paper jam.
As seen above, the above head unit 200 has the four ink-jet recording heads 220 secured to the fixing plate 250. Positioning of the ink-jet recording head 220 onto the fixing plate 250 is performed using an alignment apparatus to be described later.
Further, the head unit 200 is provided with the cover head 240, which is box-shaped to cover the respective ink-jet recording heads 220, on a side of the fixing plate 250 opposite from the ink-jet recording head 220, as shown in
The fixing portion 242 is composed of a frame portion 243 provided in correspondence with the fixing frame portion 253 of the fixing plate 250, and a beam portion 244 provided in correspondence with the fixing beam portion 254 of the fixing plate 250 to divide the opening portion 241. The fixing portion 242 comprising the frame portion 243 and the beam portion 244 is joined to the joining portion 252 of the fixing plate 250.
As noted above, the ink droplet ejection surface of the ink-jet recording head 220 and the cover head 240 are joined together without clearance. Thus, the entry of a recording medium into the clearance, if any, can be prevented to prevent deformation of the cover plate 240 and a paper jam. Moreover, the side wall portion 245 of the cover head 240 covers the outer peripheral edge portion of the plural ink-jet recording heads 220, thus reliably preventing the wraparound of ink onto the side surface of the ink-jet recording head 220.
Examples of the material for the cover head 240 are metallic materials such as stainless steel. The cover head 240 may be formed by press working or molding a plate of such a metal. Also, the cover head 240 can be grounded if it is formed of an electro conductive metallic material.
Furthermore, the cover head 240 needs a certain degree of strength in order to protect the ink-jet recording head 220 from impact by wiping or capping. Thus, the cover head 240 needs to be relatively thick. In the present embodiment, the thickness of the cover head 240 is set at 0.2 mm.
The method of joining between the cover head 240 and the fixing plate 250 is not limited, and is, for example, adhesion using a thermosetting epoxy-based adhesive agent.
The fixing portion 242 is provided with flange portions 246 having fixing holes 247 for positioning and fixing the cover head 240 onto other member. The flange portion 246 is provided to bend so as to protrude from the side wall portion 245 in the same direction as the plane direction of the ink droplet ejection surface. The cover head 240 in the present embodiment is fixed to the cartridge case 210, which is the holding member holding the ink-jet recording heads 220 and the head cases 230, as shown in
In further detail, as shown in
The cover head 240 and the fixing plate 250 having the plurality of ink-jet recording heads 220 joined thereto are fixed together, with the fixing holes 247 of the cover head 240 and the plurality of nozzle rows 21A being positioned with respect to each other. This positioning between the fixing holes 247 of the cover head 240 and the plurality of nozzle rows 21A can be performed using the alignment apparatus to be described later. Alternatively, when the fixing plate 250 and the plurality of ink-jet recording heads 220 are positioned and fixed, the cover head 240 may simultaneously be positioned and fixed.
The alignment apparatus according to an embodiment of the invention will be described in detail with reference to the accompanying drawings. The same portions as those in
As shown in
Of these members, the alignment jig 400 has a mask 410 provided with reference marks 401, abase jig 420 for setting the mask 410 in place, and a spacer jig 430 disposed on the base jig 420 for holding the fixing plate 250 as the fixing member. In this configuration, the fixing plate 250 is held on the spacer jig 430, and the relative positional relationship between the reference mark 401 of the mask 410 and the alignment mark 22 of the nozzle plate 20 is confirmed by the bifocal microscope 500. During this process, alignment between the reference mark 401 and the alignment mark 22 is performed, while the fixing plate 250 and the nozzle plate 20 of the ink-jet recording head 220 are adhered together via the adhesive agent.
In further detail, the base jig 420 comprises stainless steel or the like in the shape of a box opening at the bottom surface. In the base jig 420, a single through-hole 421 penetrating in the thickness direction is provided in a region opposed to the region of the mask 410 where the reference mark 401 is provided. The through-hole 421 corresponds positionally to a communicating hole 432 of the spacer jig 430 to be described later.
The mask 410 comprises a transparent material allowing passage of light, for example, glass such as quartz and, in the present embodiment, has protrusions 411 which protrude into the through-hole 421 of the spacer jig 420 and which have the reference marks 401 formed at leading end portions thereof. The protrusion 411 is a cylindrical portion provided for each reference mark 401. In the present embodiment, two of the alignment marks 22 are provided in the nozzle plate 20 of each ink-jet recording head 220. Thus, two of the reference marks 401 are provided for each ink-jet recording head 220, so that total eight of the reference marks 401 are provided.
The reference mark 401 is preferably formed to be at a height in the vicinity of the alignment mark 22 of the nozzle plate 20. This is intended for decreasing the distance between the alignment mark 22 and the reference mark 401 to increase positioning accuracy. That is, the greater the distance between the reference mark 401 and the alignment mark 22, the more difficult it becomes to ensure the positioning accuracy. If a great distance exists between the reference mark 401 and the alignment mark 22, the optical axis of the optical system 501, 502 (601, 602) is greatly displaced because of heat of a metal halide lamp or the like, which is used when the position is confirmed by the optical system 501,502 (601, 602). As a result, a great error occurs in the actual positions of the reference mark 401 and the alignment mark 22.
Assume that the protrusion 411 is not provided in the mask, and the distance between the alignment mark 22 and the reference mark 401 is, for example, about 5.1 mm. In this case, displacement of the optical axis reaches about 2.5 μm, at most. In the present embodiment, the provision of the protrusion 411 in the mask 410 decreases the distance between the reference mark 401 and the alignment mark 22 to 110 μm or less. By so doing, the above heat-associated displacement of the optical axis of the optical system 501,502 (601,602) can be decreased to 0.05 μm or less, thus ensuring highly accurate positioning.
If the protrusion 411 comes too close to the nozzle plate 20, the adhesive agent adhering the nozzle plate 20 and the fixing plate 250 may adhere to the leading end surface of the protrusion 411, making it impossible for the optical system 501,502 (601,602) to confirm the alignment mark 22 and the reference mark 401. Thus, the leading end surface of the protrusion 411 is preferably provided to be separated by a predetermined distance from the nozzle plate 20.
As noted above, the distance between the alignment mark 22 and the reference mark 401 is shortened by providing the mask 410 with the protrusion 411. Thus, it becomes unnecessary to shorten the distance between the reference mark 401 and the alignment mark 22 by reducing the thickness of the base jig 420. If the thickness of the base jig 420 is reduced in order to shorten the distance between the alignment mark 22 and the reference mark 401, the following problem occurs: When the ink-jet recording head 220 is pressed against the fixing plate 250, the base jig 420 is deformed or destroyed. As a result, an error occurs in the alignment between the reference mark 401 and the alignment mark 22. In the present embodiment, on the other hand, the mask 410 is provided with the protrusion 411. Thus, there is no need to form the base jig 420 thinly. Consequently, the rigidity of the base jig 420 can be maintained to prevent deformation or destruction. This can also contribute to highly accurate positioning.
The mask 410 is detachably held by the base jig 420, and can be used in other alignment jig, for example, when the fixing plate 250 and the ink-jet recording head 220 are adhered by curing of the adhesive agent. This can cut down on the cost of the alignment jig 400.
The spacer jig 430 is held on a surface of the base jig 420 opposite to its surface, on which the mask 410 is disposed, to hold the fixing plate 250. In further detail, the spacer jig 430 is provided with a plurality of suction chambers 431, each of which comprises a plate-shaped member such as stainless steel and has a suction means, such as a vacuum pump (not shown), connected to its interior. The suction chamber 431 opens to the surface of the spacer jig 430 for sucking and holding the surface of the fixing plate 250. The spacer jig 430 is provided with communicating holes 432, each of which becomes a space, so that the alignment mark 22 of the ink-jet recording head 220 held by the fixing plate 250 upon suction can be confirmed from below the bottom surface of the mask 410 through the communicating hole 432. That is, the spacer jig 430 is disposed between the fixing plate 250 and the mask 410 in such a manner as to make contact, on one surface, with the fixing plate 250 and make contact, on the other surface, with the mask 410 so that the reference mark 401 and the alignment mark 22 are opposed to each other via the space.
The pressing means 450 for pressing the ink-jet recording head 220 toward the fixing plate 250 is disposed on the above-mentioned alignment jig 400. That is, the pressing means 450 has a U-shaped arm portion 451 having both ends placed on the spacer jig 430 and arranged above the ink-jet recording head 220, and pressing portions 453 provided in the arm portion 451 for pressing the ink-jet recording heads 220 toward the fixing plate 250.
The pressing portions 453 are provided in regions of the arm portion 451 opposed the respective ink-jet recording heads 220. In the present embodiment, four of the ink-jet recording heads 220 are fixed to the single fixing plate 250. Thus, four (the same number as the number of the ink-jet recording heads 220) of the pressing portions 453 are provided in correspondence with the ink-jet recording heads 220.
Each pressing portion 453 is composed of a pressing pin 454 of a cylindrical shape inserted through the arm portion 451 and provided to be movable in the axial direction, an urging means 455 provided on a proximal end side of the pressing pin 454 for urging the pressing pin 454 toward the ink-jet recording head 220, and a pressing dowel 459 placed between the pressing pin 454 and the ink-jet recording head 220.
The pressing pin 454 has a leading end formed in a semispherical shape, and makes a point contact with the top of the pressing dowel 459 to press the pressing dowel 459.
The urging means 455 is provided in the arm portion 451 for urging the pressing pin 454 toward the ink-jet recording head 220. In the present embodiment, the urging means 455 has a thread holding portion 456 provided to surround the proximal end side of the pressing pin 454, a threaded portion 457 screwed to the thread holding portion 456, and an urging spring 458 provided between the leading end surface of the threaded portion 457 and a proximal end portion of the pressing pin 454.
Thus, the urging means 455 can adjust the pressure, with which the urging spring 458 presses the pressing pin 454, depending on the amount of clamping against the thread holding portion 456 by the threaded portion 457. By this means, the pressure with which the pressing pin 454 presses the pressing dowel 459 can be adjusted.
The pressing dowel 459 is placed between the pressing pin 454 and the protective plate 30 of the ink-jet recording head 220. The pressing pin 454 makes a point contact with the upper surface of the pressing dowel 459, and the pressing force of the pressing pin 454 is spread uniformly to nearly the entire surface of the protective plate 30 of the ink-jet recording head 220. In this state, the ink-jet recording head 220 can be pressed. Instead of bringing the leading end of the pressing pin 454 into direct contact with the top of the protective plate 30 of the ink-jet recording head 220, the whole of the ink-jet recording head 220 is pressed by the pressing dowel 459. Thus, the ink-jet recording head 220 can be reliably fixed to the fixing plate 250. The pressing dowel 459 has an outer peripheral shape of the same size as, or a slightly smaller size than, the size of the outer peripheral shape of the protective plate 30 of the ink-jet recording head 220.
As described above, the alignment jig 400 integrated with the pressing means 450 is disposed on a moving table 550, and is designed to be moved, as appropriate, in a horizontal direction perpendicular to the optical axes L1 and L2 of the bifocal microscopes 500 and 600. Thus, the moving table 550 is moved, with the optical axes L1 and L2 being fixed. By so doing, each alignment mark 22 corresponding to each ink-jet recording head 220 can be allowed to lie on the optical axes L1, L2 together with each reference mark 401. In a region of the moving table 550 where the optical axes L1, L2 pass while heading for the mask 410, through-holes 551 are provided to ensure optical paths leading to the alignment marks 22 via the reference marks 401.
The bifocal microscope 500 has one optical system 501 and another optical system 502 having the optical axis L1 in common. The optical axis L1 is pointed in the direction of the alignment mark 22 via the reference mark 401 and the communicating hole 432, as a space, from the side of the mask 410 opposite to the spacer jig. The optical system 501 can focus on the reference mark 401, while the optical system 502 can focus on the alignment mark 22.
In more detail, an objective lens 503 is accommodated in a lens-barrel 504, with the optical axis L1 being pointed in the direction of the reference mark 401 and the alignment mark 22. The lens-barrel 504 is fixed to a casing 505. Within the casing 505, two beam splitters 506 and 507, two mirrors 508 and 509, and two focal lenses 510 and 511 are accommodated.
The optical system 501 is formed from the beam splitter 506, the mirror 508, the focal lens 510, and the beam splitter 507. The optical system 501 has an optical path (indicated by dashed dotted lines in the drawing) in which light, which has passed through the beam splitter 506, is reflected by the mirror 508, passed through the focal lens 510, and then led to the outside via the beam splitter 507.
The optical system 502 is formed from the beam splitter 506, the focal lens 511, the mirror 509, and the beam splitter 507. The optical system 502 has an optical path (indicated by dashed dotted lines in the drawing) in which light, which has been reflected by the beam splitter 506, is passed through the focal lens 511, then reflected by the mirror 509 and the beam splitter 507, and then led to the outside.
A CCD 520, which is an imaging means, takes in an image of the reference mark 401 and an image of the alignment mark 22 simultaneously via the optical systems 501 and 502, and reproduces the images. By adjusting the focal position of the focal lens 510, the image of the reference mark 401 is focused onto the CCD 520. By adjusting the focal position of the focal lens 511, the image of the alignment mark 22 is focused onto the CCD 520. In this manner, clear images of the reference mark 401 and the alignment mark 22 can be focused individually on the CCD 520. The position of the ink-jet recording head 220 is adjusted such that these images are superimposed, whereby predetermined alignment is carried out.
The foregoing descriptions concern the bifocal microscope 500, and the other bifocal microscope 600 also has exactly the same configuration. Thus, the portions of the bifocal microscope 600, which correspond to the respective portions of the bifocal microscope 500, are assigned numerals obtained by adding “100” to the numerals of the respective portions of the bifocal microscope 500, in order to omit duplicate explanations.
The present embodiment has the two bifocal microscopes 500 and 600 so that the two alignment marks 22 and 22 formed at opposite end portions in the longitudinal direction of the nozzle plate 20 of the ink-jet recording head 220 can be observed at the same time, and the distance between the optical axes L1 and L2 of the bifocal microscopes 500 and 600 is in agreement with the distance between the two alignment marks 22 and 22. Hence, when the reference marks 401, 401 and the alignment marks 22, 22 are located on the optical axes L1, L2, the ink-jet recording head 220 is positioned in a predetermined manner relative to the fixing plate 250.
The procedure for the positioning is common to the two bifocal microscopes 500 and 600. The procedure simply comprises taking in the images of the two alignment marks 22 and 22 and the corresponding reference marks 401 and 401 by the two bifocal microscopes 500 and 600, and parallel-processing these images. This procedure itself is essentially the same as that for one bifocal microscope.
However, when parallel processing is performed using the two bifocal microscopes 500 and 600 as above, predetermined alignment for one ink-jet recording head 220 is completed by single positional adjustment based on the two sets of the reference marks 401 and the alignment marks 22. Thus, a prompt alignment operation can be performed, in comparison with an alignment operation based on one set of the reference mark 401 and the alignment mark 22. In the case of one bifocal microscope, in particular, predetermined alignment is carried out for one ink-jet recording head 220 with the use of the reference mark 401 and the alignment mark 22 located on one side, and then predetermined alignment is carried out with the use of the reference mark 401 and the alignment mark 22 located on the other side. During this process, the adjusted position may be displaced. In view of this possibility, the operating efficiency of the above-mentioned alignment operation using the two bifocal microscopes 500, 600 is even better.
In performing alignment using the two bifocal microscopes 500 and 600 as in the present embodiment, the optical axes L1 and L2 of the bifocal microscopes 500 and 600 need to coincide relatively with each other. Thus, there is an optical axis adjustment mask 700, as shown in
As shown in the drawing, the reference mark 401 in the present embodiment is ring-shaped, and is formed to face the surface of the protrusion 411. On the otherhand, an optical axis adjusting alignment mark 701 which is paired with the reference mark 401 takes the place of the alignment mark 22, and is formed in the optical axis adjustment mask 700. The optical axis adjustment mask 700 is fixed to the spacer jig 430 via a jig 710 for fixing the optical axis adjustment mask 700.
Thus, the reference mark 401 and the optical axis adjusting alignment mark 701 are opposed to each other via the communicating hole 432 of the spacer jig 430. The positional relationship between the reference mark 401 and the optical axis adjusting alignment mark 701 is as shown, for example, in
In the present embodiment, the optical axis adjustment mask 700 is installed via the jig 710 instead of the fixing plate 250 (see
Optical axis adjustment
The method of adjusting the optical axes L1 and L2 of the bifocal microscopes 500 and 600 in the alignment apparatus according to the present embodiment will be described.
1) As shown in
2) The reference mark 401 and the optical axis adjusting alignment mark 701 are simultaneously observed with the bifocal microscope 500 having the optical axis L1 pointed in the direction of the optical axis adjusting alignment mark 701 via the reference mark 401 from the side of the mask 410. Based on the observation, an adjustment is made such that the positional relationship between the reference mark 401 and the optical axis adjusting alignment mark 701 with respect to the X-axis direction, which is one direction in an XY-plane parallel to the optical axis adjustment mask 700, is a predetermined one. Here, one of the optical systems, 501 (see
An example of the positional relationship between the reference mark 401 and the optical axis adjusting alignment mark 701 after this adjustment is shown in
3) Similar adjustment of the positional relationship is made with respect to the Y-axis direction which is the other direction in the above-mentioned XY-plane. As a result, the relative positional relationship of the optical axis adjustment mask 700 relative to the mask 410 can be adjusted in a predetermined manner.
An example of the positional relationship between the reference mark 401 and the optical axis adjusting alignment mark 701 after this adjustment is shown in
4) The reference mark 401 and the optical axis adjusting alignment mark 701 are simultaneously observed, with the optical axis L2 of the bifocal microscope 600 being pointed in the direction of the optical axis adjusting alignment mark 701 via the reference mark 401 from the side of the mask 410. Based on the observation, an adjustment is made such that the positional relationship between the reference mark 401 and the optical axis adjusting alignment mark 701 with respect to the X-axis direction or the Y-axis direction is a predetermined one. As a result of this adjustment of the optical axis L2, the relative relationship between the optical axes L1 and L2 is held as predetermined. This completes preparations for performing an alignment operation in which the two alignment marks 22 are simultaneously observed using the two bifocal microscopes 500 and 600, and positioning of the single ink-jet recording head 220 at a predetermined position is carried out by single alignment.
Movement, etc. of the respective portions attendant on such optical axis adjustment are performed using an adjusting means (not shown).
Alignment method:
Next, an explanation will be offered for the method of aligning the ink-jet recording head 220 with a predetermined position by use of the alignment apparatus according to the present embodiment.
1) As shown in
2) As shown in
3) In the optical systems 501, 601 of the bifocal microscopes 500, 600, images of the reference marks 401, 401 are focused by the adjustment of the focal lenses 510, 610, and taken into the CCDs 520, 620. In the other optical systems 502, 602, images of the alignment marks 22, 22 are focused by the adjustment of the focal lenses 511, 611, and taken into the CCDs 520, 620. As a result, clear images focused on the reference marks 401, 401 and the alignment marks 22, 22 are incorporated into the CCDs 520, 620. That is, the optical systems (501, 502) and (601, 602) have the optical axes L1, L2 in common, but can focus individually on the objects at different positions (i.e., reference marks 401, 401 and alignment marks 22, 22). Thus, they obtain clear images of the reference marks 401, 401 and the alignment marks 22, 22 at sufficient magnification with decreased depths of field.
4) As shown in
The fixing plate 250 is positioned and held by the alignment jig 400. Thus, the mask 410 and the ink-jet recording head 220 are positioned with respect to each other, whereby the fixing plate 250 and the ink-jet recording head 220 can also be positioned with respect to each other.
Positioning of the ink-jet recording head 220 with respect to the fixing plate 250 may be performed by fine positional adjustment using a micrometer or the like (not shown) while an operator is visually recognizing the images on the CCDs 520, 620. Alternatively, the positioning may be performed automatically by subjecting the output images of the CCDs 520, 620 to image processing to drive the micrometer or the like by a drive motor or the like.
5) The same step as the step in 4) above (
6) The plurality of ink-jet recording heads 220 are pressed against the fixing plate 250 at a predetermined pressure by means of the pressing means 450, with the adhesive agent being cured, whereby the ink-jet recording heads 220 are joined to the fixing plate 250.
By so joining the fixing plate 250 and the plurality of ink-jet recording heads 220, while performing positioning, the fixing plate 250 and the nozzle rows 21A can be positioned with respect to each other with high accuracy. Moreover, the relative positioning of the nozzle rows 21A of the adjacent ink-jet recording heads 220 can be carried out with high accuracy. Furthermore, the ink-jet recording head 220 is contacted with and joined to the fixing plate 250 comprising the flat plate. Thus, simply by joining the ink-jet recording head 220 to the fixing plate 250, the relative positioning in the ink droplet ejection direction of the plurality of ink-jet recording heads 220 is performed. Hence, there is no need to align the plurality of ink-jet recording heads 220 in the ink droplet ejection direction, and deviation in the landing position of ink droplets can be prevented reliably.
In the present embodiment, in particular, the space due to the spacer jig 430 exists between the mask 410 provided with the reference marks 401, 401 and the nozzle plate 20 provided with the alignment marks 22, 22. Thus, the height positions of the reference marks 401, 401 and the alignment marks 22, 22 are different from each other. However, the focuses of the reference marks 401, 401 and the alignment marks 22, 22 can be adjusted, respectively, by the two optical systems (501, 502) and (601, 602). Consequently, the images of the reference marks 401, 401 and the alignment marks 22, 22 are so clear that highly accurate positioning can take place.
With the foregoing embodiment, optical axis adjustment is made by a combination of the movements in the X-axis direction and the Y-axis direction with the use of the reference mark 401 and the optical axis adjusting alignment mark 701 as shown in
In the above-described embodiment, the optical means is composed of the two bifocal microscopes 500 and 600, but this is not limitative. The optical means maybe an ordinary single-focus microscope. However, the use of the bifocal microscopes 500, 600 presents the aforementioned various advantages.
Needless to say, moreover, the workpiece is not limited to the ink-jet recording head 220. Besides, the pressing means 450 is provided on the alignment jig 400, but this is not limitative. For example, if an ultraviolet curing adhesive agent is used as an adhesive agent for joining the fixing plate 250 and the ink-jet recording head 220, the adhesive agent is coated onto the joining surface of the fixing plate 250. Then, with the fixing plate 250 and the ink-jet recording head 220 in contact, ultraviolet radiation is applied to cure the adhesive agent, whereby the fixing plate 250 and the ink-jet recording head 220 can be joined. Thus, the pressing means 450 can be omitted. The ultraviolet curing adhesive agent need not be cured, with the fixing plate 250 and the ink-jet recording head 220 being pressed under a predetermined pressure, unlike a thermosetting adhesive agent. If pressure is applied, the ink-jet recording head 220 and the fixing plate 250 can be joined together with high accuracy, with positional displacement between them being prevented.
Joining using the ultraviolet curing adhesive agent imparts a relatively low joining strength. Thus, it is recommendable that after the fixing plate 250 and the ink-jet recording head 220 are joined using the ultraviolet curing adhesive agent, the periphery of corners defined by the ink-jet recording head 220 and the fixing plate 250 is fixed using a thermosetting adhesive agent. By this measure, the fixing plate 250 and the ink-jet recording head 220 can be joined highly accurately and firmly to enhance reliability.
In the above embodiments, the fixing plate 250 comprising the flat plate is illustrated as the fixing member for joining the plurality of ink-jet recording heads 220 thereto. However, the fixing member is not limited to the fixing plate 250. For example, the plurality of ink-jet recording heads 220 may be directly positioned on and joined to the cover head 240. Even in this case, the plurality of ink-jet recording heads 220 can be joined, with highly accurate positioning, with the use of the aforementioned alignment jig 400.
In the above embodiments, the ink-jet recording head 220 of the flexural vibration type is illustrated, but this is not limitative. It goes without saying that the invention can be applied to head units having ink-jet recording heads of various structures, such as, for example, an ink-jet recording head of the longitudinal vibration type in which piezoelectric materials and electrode-forming materials are alternately stacked, and expanded and contracted in the axial direction, and an ink-jet recording head for ejecting ink droplets by bubbles produced by heat generation of a heat-generating element or the like.
In the above embodiments, the head unit having the ink-jet recording heads for ejection of ink as liquid-jet heads to be aligned is illustrated as an example. However, this is not limitative, and the invention can be generally applied in producing liquid-jet head units having wide varieties of liquid-jet heads. Examples of the liquid-jet heads are recording heads for use in image recording devices such as printers, color material jet heads for use in the production of color filters such as liquid crystal displays, electrode material jet heads for use in the formation of electrodes for organic EL displays and FED (face emitting displays), and bio-organic material jet heads for use in the production of biochips. It should be understood that such changes, substitutions and alterations can be made in the invention without departing from the spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-248840 | Sep 2006 | JP | national |
