Method of manufacturing an ink-jet recording head

An ink-jet recording head has a plate-shaped member including a first layer with a partition wall formed by a first etching process and defining a pressure chamber, an ink inlet passage and a common ink storage chamber, a second layer with a land formed by a second etching process so as to correspond to the pressure chamber, and an intermediate layer sandwiched between the first and the second layers. The recording head also has a pressure producing device disposed with its extremity in contact with the land, and a nozzle plate with a nozzle hole bonded to the front surface of the plate-shaped member. An ink particle is jetted through the nozzle hole when the pressure in the pressure chamber is changed by the pressure producing device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink-jet recording head and a method of manufacturing the same. More particularly, the present invention relates to an ink-jet recording head that jets ink particles through nozzle holes by changing the pressure of pressure chambers by deformations of pressure producing devices and a method of manufacturing such an ink-jet recording head.

2. Description of the Related Art

Generally, the ink-jet recording apparatus has a recording head provided with a plurality of nozzle holes arranged in a row, a scanning mechanism for moving a carriage supporting the recording head thereon in a scanning direction parallel to the width of a recording medium, such as a recording sheet, and a sheet feed mechanism for feeding a recording sheet in a feed direction parallel to the length of the recording sheet.

The recording head has a head structure provided with pressure chambers and nozzle holes respectively communicated with the pressure chambers, and pressure producing devices for changing the pressure of the ink contained in the pressure chambers. Ink particles are jetted through each nozzle hole by applying a driving pulse to the pressure producing device to change the pressure of the ink contained in the pressure chamber.

The scanning mechanism moves the carriage supporting the recording head in the scanning direction for a recording operation. During the recording operation, the recording head jets ink particles at points of time specified by dot pattern data. Upon the arrival of the recording head at the terminal point of a scanning range, the scanning mechanism returns the recording head to a starting point of the scanning range and the sheet feed mechanism moves the recording medium in the feed direction. Then, the scanning mechanism starts moving the carriage in the scanning direction and the recording head jets ink particles while the same is moved in the scanning direction. The recording head may be driven for printing during only a forward travel or may be driven for printing during both a forward travel and a return travel. These operations are repeated according to dot pattern data to record an image on the recording sheet.

Some ink-jet recording apparatus applies selectively a plurality of kinds of driving pulse of different waveforms produced from a common driving signal of a predetermined waveform to a recording head to jet ink particles of different Kinds, such as ink particles respectively having different particle sizes. The period of the common driving signal, i.e., driving period, determines the printing speed of the recording apparatus.

FIG. 30is an enlarged fragmentary sectional view of a recording head included in an ink-jet recording apparatus andFIG. 31is an enlarged sectional view of pressure chambers and portions around the pressure chambers of the recording head shown inFIG. 30. As shown inFIGS. 30 and 31, a recording head50has a flexible sheet53, a plate-shaped member52having partition walls51and attached to the front surface of the flexible sheet53, and a plate-shaped member55having a plurality of lands54and attached to the back surface of the flexible sheet53.

The partition walls51define a plurality of pressure chambers56, a plurality of ink inlet passages57and common ink storage chambers58. The pressure chambers56communicate with the common ink storage chambers58by means of the ink inlet passages57, respectively. The lands54correspond to the pressure chambers56, respectively.

The extremities of pressure producing devices59are in contact with the lands54, respectively. The pressure producing device59includes a piezoelectric vibrator of a longitudinal vibration mode having a laminated piezoelectric element. The pressure producing devices59are attached to a fixed plate60fixed to a case61.

Portions of the flexible sheet53around the lands54serve as elastic, deformable parts63capable of being elastically deformed by a deformation of the pressure producing devices59

A nozzle plate64is bonded to the front surface of the plate-shaped member52. The nozzle plate64is provided with a plurality of nozzle holes65respectively connected to the pressure chambers56.

The plurality of nozzle holes65are arranged along the feed direction on the recording head50at intervals corresponding to predetermined pitches that defines a dot density.

The extremity of an ink supply pipe66extended through the case61, the plate-shaped member55and the flexible sheet53is connected to the common ink storage chamber58to supply the ink into the common ink storage chamber58.

When manufacturing the known ink-jet recording head shown inFIGS. 30 and 31, a flat plate for forming the plate-shaped member55is attached to the back surface of the flexible sheet53, and the lands54of the flat plate are formed on the flexible sheet53by etching the flat plate.

On the other hand, the plate-shaped member52provided with the partition walls51is bonded to the front surface of the flexible sheet53with an adhesive. Therefore, as shown inFIG. 32, it sometimes occurs that part67of the adhesive spreads into the pressure chamber56and the ink inlet port57.

If the part67of the adhesive spreads into the pressure chamber56and the ink inlet port57, pressure applied to the flexible sheet53cannot be satisfactorily transmitted to the pressure chamber56due to the deterioration of the flexibility of the flexible sheet53by the detrimental effect of the adhesive on the flexible sheet53. Portions of the flexible sheet53corresponding to the different pressure chambers56have different deforming properties, respectively. As a result, the nozzle holes65have different ink jetting characteristics, respectively.

When bonding the plate-shaped member52provided with the partition walls51to the flexible sheet53, it is difficult to bond the plate-shaped member52to the flexible sheet53so that the pressure chambers56are formed accurately in correct positional relation to the lands54. Consequently, pressure cannot be properly applied to the pressure chambers. Portions of the flexible sheet53corresponding to the plurality of pressure chambers56are deformed differently. As a result, the nozzle holes65have different ink jetting characteristics, respectively.

When manufacturing the known recording head, portions of the plate-shaped member52having the partition walls51are removed by etching to form grooves for forming the ink inlet passages57before bonding the plate-shaped member52to the flexible sheet53. If the portions of the plate-shaped member52are etched unequally and the grooves are formed in different depths, respectively, the ink inlet passages57have different sectional areas, respectively. Consequently, pressure cannot be satisfactorily transmitted to the pressure chambers56. The portions of the flexible sheet53respectively corresponding the plurality of pressure chambers56are deformed differently. As a result, the nozzle openings have different ink jetting characteristics, respectively.

Generally, as shown inFIGS. 33 and 34, an ink-jet recording head (hereinafter, referred to simply as “recording head”) employing pressure producing devices each including a piezoelectric vibrator of a longitudinal vibration mode has a passage unit301provided with a plurality of nozzle holes308and a plurality of pressure chambers307, and a case302containing piezoelectric vibrators306. The passage unit301is attached to the case302.

The passage unit301is formed by superposing a nozzle plate303provided with the nozzle holes303arranged in rows, a passage plate304provided with a plurality of pressure chambers307respectively connected to the nozzle holes308, and a vibrating plate305attached to the lower surface of the passage plate304so as to cover the lower open ends of the pressure chambers307. The passage plate304is provided with ink storage chambers309connected to the pressure chambers307by ink inlet passages310.

The case302is formed of a synthetic resin and has spaces312extending between the upper and the lower surface thereof. The piezoelectric vibrators306are contained in the spaces312. The piezoelectric vibrators306have back ends fixed to base plates311attached to the case302and front ends fixed to lands305A formed on the lower surface of the vibrating plate305.

A driving signal produced by a314is transmitted through a flexible wiring plate313to the corresponding piezoelectric vibrator306to vibrate the piezoelectric vibrator longitudinally. Consequently, the land305A of the vibrating plate305is vibrated to change the pressure in the pressure chamber307, and thereby the ink contained in the pressure chamber307is jetted in ink particles through the nozzle holes308. InFIG. 33, indicated as315are ink supply ports through which the ink is supplied to the ink storage chambers309.

The passage plate304of the passage unit301is a plate formed by subjecting a single-crystal silicon substrate to an anisotropic etching process, such as that disclosed in JP-A No. Hei 9-123448, or an electroformed plate formed on a pattern by an electroforming process and removed from the pattern, such as those disclosed in JP-A No. Hei 6-305142 or Hei 9-300635.

When processing a single-crystal silicon substrate by an anisotropic etching process to form the passage plate304provided with the pressure chambers307and the ink inlet passages310, the depth of the ink inlet passage310is controlled by calculating the etching time necessary to etch the layer in a desired depth. It is difficult to achieve the accurate control of the depth of the ink inlet passages310by such a method and there is a limit to the improvement of the accuracy of the depth of the ink inlet passages310. When the passage plate304is formed by processing a photosensitive resin plate, a partition wall between the adjacent pressure chambers307is liable to be deformed by pressure applied to one of the adjacent pressure chambers307and crosstalk between the adjacent pressure chambers307occurs if the pressure chambers307are arranged in a high density because the photosensitive resin, as compared with a metal or silicon, has a low rigidity and, therefore, it is impossible to arrange the nozzle holes308in a high density. When the passage plate304is an electroformed plate, the passage plate304has a low dimensional accuracy because the electroformed plate is liable to be warped when removing the same from the pattern and the dimensional accuracy of the electroformed plate is liable to be reduced. The electroformed plate needs an additional process for removing the electroformed plate from the pattern, which is one of factors of cost increases.

In the recording head, the pressure chambers307, the ink storage chambers309and the ink inlet passages310are formed in the single passage plate304. Therefore, the passage plate304must have an area sufficient for arranging the pressure chambers307, the ink storage chambers309and the ink inlet passages310thereon, and the miniaturization of the recording head is limited by the passage plate304. Since the recording head employs the piezoelectric vibrators306of the longitudinal vibration mode, the passage unit301is liable to be deformed by the vibrations of the piezoelectric vibrators306and crosstalk is liable to occur. Therefore, the rigidity of the passage unit301must be increased to the highest possible extent, which places a restriction on the miniaturization of the recording head.

The passage plate304of the conventional recording head is a plate formed by subjecting a single-crystal silicon substrate to an anisotropic etching process, a plate formed by processing a photosensitive resin plate or an electroformed plate. The depth of the passages of the passage plate304formed by subjecting a single-crystal silicon substrate to an anisotropic etching process is controlled by calculating the etching time. Therefore it is difficult to form the passages accurately in a desired depth, which is a restriction on accuracy improvement. When the passage plate304is formed by processing a photosensitive resin plate, the partition wall between the adjacent pressure chambers307is liable to be deformed and crosstalk between the adjacent pressure chambers307occurs if the pressure chambers307are arranged in a high density because the photosensitive resin has a low rigidity and, therefore, it is impossible to arrange the nozzle holes308in a high density. When the passage plate304is an electroformed plate, the passage plate304has a low dimensional accuracy because the electroformed plate is liable to be warped when removing the same from the pattern and the dimensional accuracy of the electroformed plate is liable to be reduced. The electroformed plates needs an additional process for removing the electroformed plate from the pattern, which is one of factors of cost increases.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing problems and it is therefore an object of the present invention to provide an ink-jet recording head having a very small unevenness in ink jetting characteristics of nozzle holes, and a method of manufacturing such an ink-jet recording head.

Another object of the present invention is to provide an ink-jet recording head advantageous for accuracy improvement and dot density increase, and to provide a method of manufacturing such an ink-jet recording head.

A third object of the present invention to provide an ink-jet recording head capable of being formed in very small dimensions and advantageous to increasing the level of integration.

According to the present invention, an ink-jet recording head comprises: a pressure producing device for changing a pressure in a pressure chamber containing an ink; a plate-shaped member having a front surface and a back surface, the plate-shaped member having a partition wall formed on the front surface by a first etching process, the partition wall defining the pressure chamber, an ink inlet passage and a common ink storage chamber, the plate-shaped member having a land formed on the back surface by a second etching process so as to correspond to the pressure chamber and be in contact with an extremity of the pressure producing device, the plate-shaped member having an elastic and deformable portion which is formed by the first etching process and the second etching process so as to surround the land, the elastic and deformable portion being capable of being elastically deformed by a deformation of the pressure producing device; and a nozzle plate provided with a nozzle hole through which an ink particle is jetted when the pressure in the pressure chamber is changed by the deformation of the pressure producing device, the nozzle plate being disposed on a side of the front surface of the plate-shaped member.

Preferably, the plate-shaped member includes a first layer having the front surface, a second layer having the back surface and an intermediate layer sandwiched between the first layer and the second layer, the first etching process etches a desired portion of the first layer selectively over the intermediate layer so that the first layer is penetrated, and the second etching process etches a desired portion of the second layer selectively over the intermediate layer so that the second layer is penetrated.

Preferably, the plate-shaped member includes a first layer having the front surface, a second layer having the back surface, an intermediate layer sandwiched between the first layer and the second layer, a first adhesive layer bonding the first layer and the intermediate layer together and a second adhesive layer bonding the second layer and the intermediate layer together, the first etching process etches a desired portion of the first layer selectively over the first adhesive layer so that the first layer is penetrated, and the second etching process etches a desired portion of the second layer selectively over the second adhesive layer so that the second layer is penetrated.

Preferably, the first and the second layers are formed of a stainless steel, and the intermediate layer is formed of a polymer film.

Preferably, the plate-shaped member is formed of a single sheet which is made of a single material, the first etching process etches a desired portion of the front surface of the plate-shaped member in a depth equal to part of a thickness of the plate-shaped member, and the second etching process etches a desired portion of the back surface of the plate-shaped member in a depth equal to part of the thickness of the plate-shaped member.

Preferably, the plate-shaped member is made of a stainless steel.

According to the present invention, an ink-jet recording head comprises: a pressure producing device for changing a pressure in a pressure chamber containing an ink; a plate-shaped member having a front surface, a back surface, the plate-shaped member having a partition wall formed on the front surface, the partition wall defining the pressure chamber, an ink inlet passage and a common ink storage chamber, the plate-shaped member having a land formed on the back surface so as to correspond to the pressure chamber and be in contact with an extremity of the pressure producing device, the plate-shaped member having an elastic and deformable portion surrounding the land and being capable of being elastically deformed by a deformation of the pressure producing device, the plate-shaped member including a first layer having the front surface, a second layer having the back surface, and an intermediate layer sandwiched between the first and the second layers, and not having any adhesive layer or the like between the first and the intermediate layers nor between the second and the intermediate layers; and a nozzle plate provided with a nozzle hole through which an ink particle is jetted when the pressure in the pressure chamber is changed by a deformation of the pressure producing device, the nozzle plate being disposed on a side of the front surface of the plate-shaped member.

Preferably, the partition wall is formed by etching a desired portion of the first layer selectively over the intermediate layer by a first etching process so that the first layer is penetrated, and the land is formed by etching a desired portion of the second layer selectively over the intermediate layer by a second etching process so that the second layer is penetrated.

Preferably, the plate-shaped member is formed of a single sheet which is made of a single material, the partition wall is formed by etching a desired portion of the plate-shaped member from the front surface by a first etching process in a depth equal to part of a thickness of the plate-shaped member, and

the land is formed by etching a desired portion of the plate-shaped member from the back surface by a second etching process in a depth equal to part of the thickness of the plate-shaped member.

Preferably, the plate-shaped member is made of a stainless steel.

Preferably, the ink-jet recording head further comprises a base member sandwiched between the plate-shaped member and the nozzle plate, the base member having an auxiliary ink storage chamber communicated with the common ink storage chamber.

Preferably, the auxiliary ink storage chamber is offset from a position corresponding to the common ink storage chamber and partly overlaps the ink inlet passage.

Preferably, the ink-jet recording head further comprises a base member sandwiched between the plate-shaped member and the nozzle plate, wherein the plate-shaped member and the nozzle plate are bonded to the base member with polyolefin adhesive films.

Preferably, an adhesive receiving groove is formed in the front surface of the plate-shaped member corresponding to the partition wall to suppress a protrusion of an adhesive when bonding the nozzle plate or the base member to the front surface of the plate-shaped member with the adhesive.

According to the present invention, an ink-jet recording head manufacturing method of manufacturing an ink-jet recording head comprising a pressure producing device for changing a pressure in a pressure chamber containing an ink; a plate-shaped member having a front surface and a back surface, the plate-shaped member having a partition wall formed on the front surface defining the pressure chamber, an ink inlet passage and a common ink storage chamber, the plate-shaped member having a land formed on the back surface so as to correspond to the pressure chamber and be in contact with an extremity of the pressure producing device, the plate-shaped member having an elastic and deformable portion surrounding the land and being capable of being elastically deformed by a deformation of the pressure producing device; and a nozzle plate provided with a nozzle hole through which an ink particle is jetted when the pressure in the pressure chambers is changed by the deformation of the pressure producing device, the nozzle plate being disposed on a side of the front surface of the plate-shaped member; the ink-jet recording head manufacturing method comprises: a first etching step for etching the plate-shaped member to form the partition wall on the front surface of the plate-shaped member;

a second etching step for etching the plate-shaped member to form the land on the back surface of the plate-shaped member; and a nozzle plate attaching step for attaching the nozzle plate directly to or via another member to the front surface of the plate-shaped member.

Preferably, the plate-shaped member includes a first layer having the front surface, a second layer having the back surface and an intermediate layer sandwiched between the first and the second layers, the first etching step etches a desired portion of the first layer selectively over the intermediate layer so that the first layer is penetrated, and the second etching step etches a desired portion of the second layer selectively over the intermediate layer so that the second layer is penetrated.

Preferably, the plate-shaped member includes a first layer having the front surface, a second layer having the back surface, an intermediate layer sandwiched between the first and the second layers, a first adhesive layer bonding the first layer and the intermediate layer together and a second adhesive layer bonding the second layer and the intermediate layer together, the first etching step etches a desired portion of the first layer selectively over the first adhesive layer so that the first layer is penetrated, and the second etching step etches a desired portion of the second layer selectively over the second adhesive layer so that the second layer is penetrated.

Preferably, the plate-shaped member is formed of a single sheet which is made of a single material, the first etching step etches a desired portion of the front surface of the plate-shaped member in a depth equal to part of a thickness of the plate-shaped member, and the second etching step etches a desired portion of the back surface of the plate-shaped member in a depth equal to part of the thickness of the plate-shaped member.

Preferably, the ink-jet recording head manufacturing method further comprises a step of disposing a base member having an auxiliary ink storage chamber communicated with the common ink storage chamber between the plate-shaped member and the nozzle plate.

Preferably, the auxiliary ink storage chamber is disposed so that the auxiliary ink storage chamber is offset from a position corresponding to the common ink storage chamber and partly overlaps the ink inlet passage.

Preferably, the ink-jet recording head manufacturing method further comprises steps of disposing a base member between the plate-shaped member and the nozzle plate, and bonding the plate-shaped member and the nozzle plate to the base member with polyolefin adhesive films.

Preferably, an adhesive receiving groove is formed in the front surface of the plate-shaped member corresponding to the partition wall to suppress a protrusion of the adhesive when bonding the nozzle plate or the base member to the front surface of the plate-shaped member with the adhesive.

According to the present invention, an ink-jet recording head comprises: a passage unit formed by superposing a nozzle plate having a nozzle hole, a passage plate provided with a passage including a pressure chamber communicated with the nozzle hole, and a vibrating plate covering an open end of the pressure chamber; and a pressure producing device for deforming the vibrating plate to change a pressure in the pressure chamber;

wherein the passage plate has a front surface and a back surface, a connecting hole is formed in the front surface of the passage plate by a first etching process so as to be communicated with the nozzle hole, and the passage is formed in the back surface of the passage plate by a second etching process.

Preferably, the passage plate has a laminated structure including a first base plate having the front surface and provided with the connecting hole formed by the first etching process, a second base plate having the back surface and provided with the passage formed by the second etching process, and an etch terminating layer sandwiched between the first and the second base plates; the connecting hole is formed by etching a desired portion of the first base plate by the first etching process which is terminated by the etch terminating layer; and

the passage is formed by etching a desired portion of the second base plate by the second etching process which is terminated by the etch terminating layer.

Preferably, the connecting hole formed in the first base plate serves also as the nozzle hole, and the first base plate serves also as the nozzle plate.

Preferably, the etch terminating layer is formed of an adhesive layer.

Preferably, the second base plate is made of a metal, and the etch terminating layer is made of a metal which is harder to be etched than the metal forming the second base plate.

Preferably, the metal forming the second base plate is a stainless steel or nickel, and the metal forming the etch terminating layer is titanium, silver or gold.

Preferably, the passage plate is formed of a single sheet which is made of a single material, the first etching process etches a desired portion of the front surface of the passage plate in a depth equal to part of a thickness of the passage plate, and the second etching process etches a desired portion of the back surface of the passage plate in a depth equal to part of the thickness of the passage plate.

Preferably, the passage plate is made of a stainless steel.

Preferably, the pressure producing device is a piezoelectric vibrator of a longitudinal vibration mode.

Preferably, the pressure producing device is a piezoelectric vibrator of a flexural vibration mode.

Preferably, the passage formed in the back surface of the passage plate by the second etching process is a space forming the pressure chamber, an ink inlet passage through which an ink is supplied into the pressure chamber, and an ink storage chamber for storing an ink to be supplied into the pressure chamber.

Preferably, an auxiliary ink storage chamber is formed in the front surface of the passage plate so as to be communicated with the ink storage chamber.

Preferably, the ink-jet recording head further comprises an additional passage plate having same construction as the passage plate and superposed on the passage plate.

Preferably, a metal layer is attached to the back surface of the passage plate, and the metal layer is provided with a passage similar to the passage.

According to the present invention, an ink-jet recording head manufacturing method of manufacturing an ink-jet recording head comprising: a passage unit formed by superposing a nozzle plate having a nozzle hole, a passage plate provided with a passage including a pressure chamber communicated with the nozzle hole, and a vibrating plate covering an open end of the pressure chamber, and a pressure producing device for deforming the vibrating plate to change a pressure in the pressure chamber, the ink-jet recording head manufacturing method comprises:

a first etching step for etching a plate-shaped member having a front surface and a back surface to form a connecting hole in the front surface so as to be communicated with the nozzle hole;

a second etching step for etching the plate-shaped member to form the passage including the pressure chamber in the back surface of the plate-shaped member; and an assembling step for assembling the passage unit by laminating the nozzle plate and the vibrating plate to the front and the back surfaces, respectively, of the passage plate which is the plate-shaped member processed by the first and the second etching processes.

Preferably, the plate-shaped member includes a first member having the front surface, a second member having the back surface and an etch terminating layer sandwiched between the first and the second members, the first and the second etching processes are terminated by the etch terminating layer.

Preferably, the passage plate is formed of a single sheet which is made of a single material, the first etching process etches a desired portion of the front surface of the passage plate in a depth equal to part of a thickness of the passage plate, and the second etching process etches a desired portion of the back surface of the passage plate in a depth equal to part of the thickness of the passage plate.

Preferably, the passage formed in the back surface of the passage plate by the second etching process is a space forming the pressure chamber, an ink inlet passage through which an ink is supplied into the pressure chamber, and an ink storage chamber for storing an ink to be supplied into the pressure chamber.

Preferably, an auxiliary ink storage chamber is formed in the front surface of the plate-shaped member so as to be communicated with the ink storage chamber when forming the connecting hole by the first etching process.

According to the present invention, an ink-jet recording head comprises: a passage unit including a nozzle plate having a nozzle hole, a passage plate provided with a pressure chamber communicated with the nozzle hole and an ink storage chamber for storing an ink to be supplied into the pressure chamber, and a vibrating plate covering an open end of the pressure chamber; and a piezoelectric vibrator of a longitudinal vibration mode for deforming the vibrating plate to change a pressure in the pressure chamber; wherein the passage plate includes a first base plate provided with the pressure chamber, a second base plate provided with a connecting hole connecting the pressure chamber to the nozzle hole and the ink storage chamber, and an ink inlet passage plate provided with an ink inlet passage connecting the pressure chamber to the ink storage chamber and sandwiched between the first and the second base plates, the ink storage chamber at least partly overlapping the pressure chamber; and the first base plate includes a first etching plate provided with the pressure chamber, a fist etch terminating layer serving as the vibrating plate, and a second etching plate forming a land to be in contact with the piezoelectric vibrator on a surface of the vibrating plate; the pressure chamber being formed by etching a desired portion of the first etching plate to the first etch terminating layer, and the land is formed by etching a desired portion of the second etching plate to the second etch terminating layer.

Preferably, a damping chamber capable of absorbing a pressure variation in the ink storage chamber is formed in the second base plate on a side of the nozzle plate.

Preferably, the second base plate includes a third etching plate provided with the ink storage chamber, a fourth etching plate provided with the damping chamber, and a second etch terminating layer sandwiched between the third and the fourth etching plates, the ink storage chamber is formed by etching a desired portion of the third etching plate to the second etch terminating layer, and the damping chamber is formed by etching a desired portion of the fourth etching plate to the second etch terminating layer.

Preferably, the etch terminating layer is an adhesive layer.

Preferably, the etching plate is made of a metal, and the etch terminating layer is made of a metal harder to be etched than the meal forming the etching plate.

Preferably, the metal forming the etching plate is a stainless steel or nickel, and the metal forming the etch terminating layer is titanium, silver or gold.

Preferably, the etch terminating layer is a polymer film, and the etch terminating layer is laminated to the etching plate via an adhesive layer.

According to the present invention, an ink-jet recording head comprises: a passage unit including a nozzle plate having a nozzle hole, a passage plate provided with a pressure chamber communicated with the nozzle hole, an ink storage chamber for storing an ink to be supplied into the pressure chamber, and a vibrating plate covering an open end of the pressure chamber; and a pressure producing device for deforming the vibrating plate to change a pressure in the pressure chamber; wherein the passage plate includes a laminated structure formed by sandwiching an etch terminating layer between a pair of etching plates, at least either the pressure chamber or the ink storage chamber is formed by etching a desired portion of the etching plate to the etch terminating layer, and the etch terminating layer serves as at least either a flexible plate defining a part of the ink storage chamber or the vibrating plate.

According to the present invention, an ink-jet recording head manufacturing method of manufacturing an ink-jet recording head comprising a passage unit including a nozzle plate having a nozzle hole, a passage plate provided with a pressure chamber communicated with the nozzle hole, an ink storage chamber for storing an ink to be supplied into the pressure chamber and a vibrating plate covering an open end of the pressure chamber, and a pressure producing device with a longitudinal vibrating mode for deforming the vibrating plate to change a pressure in the pressure chamber; the ink-jet recording head manufacturing method comprises the steps of: forming a laminated structure by sandwiching a first etch terminating layer between a first etching plate and a second etching plate; forming the pressure chamber by etching a desired portion of the first etching plate to the first etch terminating layer; forming a land by etching a desired portion of the second etching plate to the first etch terminating layer; and bonding a second base plate provided with a connecting hole for connecting the pressure chamber to the nozzle hole and the ink storage chamber to a first base plate having the laminated structure provided with the pressure chamber and the land so that the ink storage chamber at least partly overlap the pressure chamber.

Preferably, the ink-jet recording head manufacturing method further comprises the step of forming the second base plate which comprises the steps of: forming a laminated structure by sandwiching a second etch terminating layer between a third etching plate and a fourth etching plate; forming the ink storage chamber and the connecting hole by etching desired portions of the third etching plate to the second etch terminating layer; and forming a damping chamber by etching a desired portion of the fourth etching plate to the second etch terminating layer, the damping chamber being capable of absorbing a pressure variation in the ink storage chamber.

Preferably, the ink-jet recording head manufacturing method further comprises the step of sandwiching an ink inlet passage plate provided with an ink inlet passage connecting the ink storage chamber to the pressure chamber between the first and the second base plates.

Preferably, the nozzle plate, the second base plate, the ink inlet passage plate and the first base plate are bonded together by adhesive films, portions of the adhesive films corresponding to openings formed in the nozzle plate, the second base plate, the ink inlet passage plate and the first base plate, respectively, are removed before the adhesive films are attached to the nozzle plate, the second base plate, the ink inlet passage plate and the first base plate.

Since the partition wall is formed in the front surface of the plate-shaped member by the first etching process and the land is formed in the back surface of the plate-shaped member by the second etching process, any adhesive does not protrude into the pressure chamber and the ink inlet passage, the pressure chamber and the land are aligned with an improved accuracy and the difference in ink jetting characteristic between the nozzle openings can be reduced.

Preferably, the plate-shaped member is formed by sandwiching the intermediate layer between the first and the second layers. The first layer can be etched through selectively over the intermediate layer without etching the intermediate layer. Therefore, the sectional area of the ink inlet passage is dependent only on the thickness of the first layer. The difference in sectional area between the ink inlet passages can be reduced and thereby the difference in ink jetting characteristics between the nozzle holes can be reduced.

The ink-jet recording head of the present invention has the base plate provided in the front and the back surfaces thereof with the connecting hole and the passage formed by the first and the second etching processes. Therefore, the ink-jet recording head, as compared with the conventional ink-jet recording head provided with a passage plate coated with a photosensitive resin film, can be provided with rigid partition wall defining the pressure chamber and the pressure chambers can be arranged in a high density. Since the ink-jet recording head does not have any components formed by electroforming on patterns and removed from the patterns, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost. The pressure chamber and the connecting hole can be accurately aligned with each other.

Preferably, the passage plate is formed by laminating the first base plate, the etch terminating layer and the second base plate, the connecting hole and the passage are formed by etching portions of the first and the second base plates corresponding to the connecting hole and the passage to the etch terminating layer. Therefore, the depths of the connecting hole and the passage are dependent on the thicknesses of the first and the second base plates and are not dependent on the etching time. Consequently, the connecting hole and the passage are formed highly accurately in desired depths, respectively.

The ink-jet recording head manufacturing method of the present invention forms the connecting hole and the passage in the front and the back surfaces of the plate-shaped member by the first and the second etching processes. Therefore, the ink-jet recording head manufacturing method of the present invention, as compared with the conventional ink-jet recording head manufacturing method that laminates a photosensitive resin film to a passage plate, is able to form rigid partition wall defining the pressure chamber and to arrange the pressure chambers in a high density. Since the ink-jet recording head manufacturing method does not need any electroforming process that forms a member on a pattern and removes the member from the pattern, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost. The pressure chamber and the connecting hole can be accurately aligned with each other.

Preferably, the plate-shaped member is formed by laminating the first base plate, the etch terminating layer and the second base plate, and the connecting hole and the passage are formed by etching portions of the first and the second base plates corresponding to the connecting hole and the passage to the etch terminating layer. The depths of the connecting hole and the passage are dependent on the thicknesses of the first and the second base plates and not dependent on the etching time. Consequently, the connecting hole and the passage can be very accurately formed in desired depths, respectively.

In the ink-jet recording head of the present invention, the pressure chamber and the ink storage chamber are formed on different levels, respectively, so that the ink storage chamber overlaps the pressure chamber partly. Therefore, the passage unit can be formed in an area far smaller than that of the passage unit of the conventional ink-jet recording head, and hence the ink-jet recording head can be greatly miniaturized, which is advantageous to increasing the level of integration. Since the passage unit can be formed in a comparatively great thickness, the longitudinal rigidity of the piezoelectric vibrator of a longitudinal vibration mode can be greatly increased and crosstalk attributable to the deformation of the passage unit can be suppressed.

The ink-jet recording head manufacturing method of the present invention forms the pressure chamber and the land by etching the first etching plate and the second etching plate to the first etch terminating layer, respectively. Therefore, the depth of the pressure chamber and the thickness of the land are dependent on the respective thicknesses of the first and the second etching plates, respectively, and not dependent on the etching time. Consequently, the pressure chamber can be accurately formed in a desired depth and the land can be accurately formed in a desired thickness. Since the rigid partition wall defining the pressure chamber can be formed, the pressure chambers can be arranged in a high density. Since the ink-jet recording head manufacturing method does not need any electroforming process that forms a member on a pattern and removes the member from the pattern, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost.

Preferably, the ink storage chamber and the damping chamber are formed by etching the third and the fourth etching plates to the second etch terminating layer. Since the depths of the ink storage chamber and the damping chamber are dependent on the thicknesses of the third and the fourth etching plates and not dependent on the etching time, the ink storage chamber and the damping chamber can be highly accurately formed in desired depths. Since the ink-jet recording head manufacturing method does not need any process that removes a member from a pattern, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 1showing an ink-jet recording head1in a first embodiment according to the present invention, a plate-shaped member2includes a first layer4, a second layer5and an intermediate layer6sandwiched between the first layer4and the second layer5. The first layer4has an outer surface as the front surface2aof the plate-shaped member2, the second layer5has an outer surface as the back surface2bof the plate-shaped member2, and the intermediate layer6is a flexible sheet. The plate-shaped member2is attached to a case3with the back surface2bthereof in contact with the front surface of the case3.

As shown inFIGS. 1 and 2, partition walls7are formed in the first layer4by a first etching process on the side of the front surface2aof the plate-shaped member2. The partition walls7define a plurality of pressure chambers8, a plurality of ink inlet passages9and a common ink storage chamber10. The common ink storage chamber10communicates with the pressure chambers8by means of the ink inlet passages9. The first etching process is, for example, a wet etching process.

As shown inFIGS. 1 and 3, a plurality of lands11are formed in the second layer5at positions respectively corresponding to the plurality of pressure chambers8by a second etching process on the side of the back surface2bof the plate-shaped member2. The second etching process is, for example, a wet etching process.

As shown inFIGS. 1 and 4, a plurality of pressure producing devices12each including a piezoelectric vibrator of a longitudinal vibration mode having a laminated piezoelectric element are held in the case with their extremities attached respectively to the lands11. As shown inFIG. 1, pressure producing devices12are held on a fixed plate13fastened to the case3. A flexible cable14is connected to pressure producing devices12.

As shown inFIGS. 1 and 4, portions of the intermediate layer6around the lands11are elastically deformable parts15capable of being deformed by deformations of the pressure producing devices12.

As shown inFIG. 1, a base member16is attached to the front surface2aof the plate-shaped member2. The base member16is provided with connecting holes17respectively connected to the pressure chambers8. A nozzle plate18is attached to the front surface of the base member16. The nozzle plate18is provided with nozzle holes19respectively connected to the connecting holes17. The nozzle holes19are arranged along several lines respectively parallel to the feed direction. The nozzle holes19are arranged in the feed direction at predetermined pitches corresponding to dot density.

An ink supply pipe20is extended through the case3, the second layer5and the intermediate layer6and is connected to the common ink storage chamber10to supply the ink to the common ink storage chamber10.

Each of the pressure producing devices12of the ink-jet recording head1has a characteristic to contract in a direction perpendicular to an electric field when charged and to extend in a direction perpendicular to an electric field when discharged. In this ink-jet recording head1, the pressure producing device12contracts when charged to pull the land11backward so that the pressure chamber8is expanded, and extends when discharged to push the land11forward so that the pressure chamber8is compressed and the pressure contained in the pressure chamber8rises.

A common driving signal COM or a print data signal SI is applied through the flexible cable14to the pressure producing device12to jet an ink particle through the nozzle hole19by operating the pressure producing device12by a predetermined driving pulse.

A method of manufacturing the ink-jet recording head in the first embodiment will be described hereinafter. The plate-shaped member2is formed by sandwiching the intermediate layer6between the first layer4and the second layer5. The plate-shaped member2may be any one of those shown inFIGS. 5A,5B and5C. The plate-shaped member2shown inFIG. 5Ahas an intermediate layer6formed of a polyimide resin (PI), and a first layer4and a second layer5formed of a stainless steel. The intermediate layer6may be formed of titanium. Various materials may be used in proper combinations for forming the first layer4, the second layer and the intermediate layer6. Essentially, a combination of materials is determined selectively so that the first layer4and the second layer5can be etched selectively over the intermediate layer6.

The plate-shaped member2shown inFIG. 5Bhas an intermediate layer6formed of a polymeric material, such as PPS, and a first layer4and a second layer5formed of a stainless steel. The first layer4and the intermediate layer6are bonded together by a first adhesive layer21, and the second layer5and the intermediate layer are bonded together by a second adhesive layer22.

The plate-shaped member2shown inFIG. 5Chas a first layer4, a second layer5and an intermediate layer6formed of a stainless steel. The first layer4and the intermediate layer6are bonded together by a first adhesive layer21, and the second layer5and the intermediate layer6are bonded together by a second adhesive layer22.

The first etching process etches through the first layer4in a predetermined pattern from the side of the front surface2aof the plate-shaped member2to form the partition walls7by the etched first layer4. Parameters of the first etching process are determined so that the first layer4is etched selectively over the intermediate layer6.

The second etching process etches through the second layer5in a predetermined pattern from the back surface2bof the plate-shaped member2to form the plurality of lands11by the etched second layer5. Parameters of the second etching process are determined so that the second layer5is etched selectively over the intermediate layer6.

The base member16is bonded to the front surface2aof the plate-shaped member2, and the nozzle plate18is bonded to the outer surface of the base member16by a nozzle plate attaching process.

As mentioned above, the front surface2aand the back surface2bof the plate-shaped member2are subjected to the first and the second etching processes, respectively, to form the partition walls7in the side of the front surface2aand to form the lands11in the side of the back surface2b. Therefore, any adhesive does not protrude into the pressure chambers8and the ink inlet passages9, the accuracy of the positional relation between the pressure chambers8and the lands11is improved and the difference in ink jetting characteristic between the nozzle holes19can be reduced.

The portions of the first layer4can be removed in the desired pattern by etching without etching the intermediate layer6by the first etching process that etches the first layer4selectively over the intermediate layer6. Consequently, the sectional areas of the ink inlet passages9are dependent on the thickness of the first layer4, the difference in sectional area between the ink inlet passages9is reduced and hence the difference in ink jetting characteristic between the nozzle holes19can be reduced.

In a first modification of the ink-jet recording head in the first embodiment, the base member16may be omitted and the nozzle plate18may be bonded directly to the front surface2aof the plate-shaped member2as shown inFIG. 6.

In a second modification of the ink-jet recording head in the first embodiment, polyolefin adhesive films23may be used for bonding together the base member16and the plate-shaped member2and bonding together the base member16and the nozzle plate18.

An ink-jet recording head in a second embodiment according to the present invention will be described hereinafter with reference toFIG. 8. The ink-jet recording head in the second embodiment is a modification of the ink-jet recording head in the first embodiment and hence parts like or corresponding to those of the ink-jet recording head in the first embodiment are denoted by the same reference characters and the description thereof will be omitted only particulars specific to the second embodiment will be described.

As shown inFIG. 8, the base member16is provided with auxiliary ink storage chamber30connected to the common ink storage chamber10, and auxiliary pressure chambers31respectively connected to the pressure chambers8. The auxiliary ink storage chamber30is offset from the position corresponding to the common ink storage chamber10and partly overlaps the ink inlet passages9. The auxiliary pressure chambers31are offset from the positions corresponding to the pressure chambers8.

The auxiliary ink chamber30and the auxiliary pressure chambers31are effective in forming a common ink storage chamber having a sufficient volume and pressure chambers each having a sufficient volume when the first layer4cannot be formed in a thickness sufficient for forming the common ink storage chamber10and the pressure chambers8respectively having sufficient volumes. Although the depth of the auxiliary pressure chambers31is about half the thickness of the base member16, the auxiliary pressure chambers31may be formed in a depth equal to the thickness of the base member16as indicated by broken lines inFIG. 8.

Since the auxiliary ink storage chamber30is offset from the position corresponding to the common ink storage chamber10, crosstalk between the adjacent pressure chambers8can be prevented, and bubbles can be easily transferred from the common ink storage chamber10to the pressure chambers8and can be readily discharged through the nozzle holes19.

An ink-jet recording head in a third embodiment according to the present invention will be described with reference toFIG. 9. The ink-jet recording head in the third embodiment is a modification of the ink-jet recording head in the foregoing embodiments and hence parts like or corresponding to those of the foregoing embodiments are denoted by the same reference characters and the description thereof will be omitted. Only particulars specific to the ink-jet recording head in the third embodiment will be described.

As shown inFIG. 9, a plurality of adhesive receiving grooves40are formed in portions of the front surface2aof the plate-shaped member2corresponding to the partition walls7. When bonding the nozzle plate8or the base member16to the front surface2aof the plate-shaped member2with an adhesive, excessive part of the adhesive is forced into the adhesive receiving grooves40, so that the adhesive does not protrude into the pressure chambers8and the ink inlet passages9.

Since the protrusion of the adhesive into the pressure chambers8and the ink inlet passages9can be suppressed, the performance deterioration of the ink-jet recording head due to the protrusion of the adhesive into the pressure chambers8and the ink inlet passages9can be prevented.

An ink-jet recording head in a fourth embodiment according to the present invention will be described with reference toFIG. 10. The ink-jet recording head in the fourth embodiment is a modification of the ink-jet recording head in the foregoing embodiments and hence parts like or corresponding to those of the foregoing embodiments are denoted by the same reference characters and the description thereof will be omitted only particulars specific to the ink-jet recording head in the fourth embodiment will be described.

Referring toFIG. 10, the plate-shaped member2is formed by etching a single sheet which is made of a single material, such as a stainless steel sheet. The front surface2aof the plate-shaped member2, i.e., a stainless steel sheet, is etched in a depth equal to part of the thickness of the plate-shaped member2by the first etching process described above referring toFIG. 1to form the partition walls7. Preferably, the first etching process is a dry etching process capable of accurately controlling etch depth.

The back surface2bof the plate-shaped member2is etched in a depth equal to part of the thickness of the plate-shaped member2by the second etching process described above referring toFIG. 1to form the plurality of lands11. Preferably, the second etching process is a dry etching process capable of accurately controlling etch depth.

After the first and the second etching processes are completed, the elastically deformable parts remain around the lands11in the plate-shaped member2. In other words, the elastically deformable parts are formed by reducing the thickness of the plate-shaped member2from both sides thereof around the lands11.

According to the present embodiment, the numbers of necessary parts and necessary steps for producing the plate-shaped member2can be reduced because the plate-shaped member2is made of a single sheet which is made of a single material.

An ink-jet recording head in a fifth embodiment according to the present invention will be described with reference toFIGS. 11A,11B and11C. The ink-jet recording head in the fifth embodiment employs piezoelectric vibrators106of a longitudinal vibration mode. As shown inFIGS. 11A,11B and11C, the ink-jet recording head has a passage unit101provided with nozzle holes108and pressure chambers107, and a case102containing the piezoelectric vibrators106. The passage unit101is attached to the case102.

The passage unit101is formed by superposing and bonding together a nozzle plate103of a stainless steel provided with the nozzle holes108, a passage plate104provided with pressure chambers107connected to the nozzle holes108, and a vibrating plate105covering the open back ends of the pressure chambers107. The passage plate104has a front surface104aand a back surface104b.

The passage plate104is formed by superposing a first base plate120provided with connecting holes121connected to the nozzle holes108, an etch terminating layer125and a second base plate122. The etch terminating layer125is formed on the back surface of the first base plate120, and the second base plate122is attached to the etch terminating layer125.

There are not any particular restrictions on the material for forming the first base plate120, provided that the material is properly rigid and is capable of being etched. Suitable materials for forming the first base plate120include stainless steels, nickel, aluminum, iron, copper and zinc. Stainless steels and nickel are preferable materials because these metals are excellent in corrosion resistance and can be comparatively easily etched.

There are not any particular restrictions on the material for forming the second base plate122, provided that the material is properly rigid and is capable of being etched. Suitable materials for forming the second base plate122include stainless steels, nickel, aluminum, iron, copper and zinc. Stainless steels and nickel are preferable materials because these metals are excellent in corrosion resistance and can be comparatively easily etched.

There are not any particular restrictions on the material for forming the etch terminating layer125provided that etch terminating layer125is unsusceptible to etching actions exerted thereon by the etching processes to which a laminated structure formed by bonding together the first base plate120, the etch terminating layer125and the second base plate122is subjected to etch the first base plate120and the second base plate122. Suitable materials for forming the etch terminating layer125include thermosetting adhesives, such as epoxy adhesives, urethane adhesives and polyester adhesives, and thermoplastic adhesives, such as polyimide adhesives. These adhesives contain a volatile component in a small concentration and do not become porous after the volatile component has been volatilized. The etch terminating layer125may be made of a metal that is harder to be etched than the materials forming the first base plate120and the second base plate122. The etch terminating layer125may be made of titanium, gold, silver or the like.

The first base plate120is etched through from its upper surface as viewed inFIG. 11A, i.e., the front surface104aof the passage plate104, such that portions of the etch terminating layer125are exposed in a predetermined pattern to form the connecting holes121to be connected to the nozzle holes108.

The second base plate122is etched through from its lower surface as viewed inFIG. 11A, i.e., the back surface of the passage plate104, such that portions of the etch terminating layer125are exposed in a predetermined pattern to form the pressure chambers107, the ink inlet passages110connected to the pressure chambers107and ink storage chambers109for storing the ink to be supplied to the pressure chambers107.

The case102is formed of a synthetic resin and has spaces112extending between the upper and the lower surface thereof. The piezoelectric vibrators106are contained in the spaces112. The piezoelectric vibrators106have back ends fixed to base plates111attached to the case102and front ends fixed to lands105A formed on the vibrating plate105.

A driving signal produced by a driving circuit114is transmitted through a flexible wiring plate113to the corresponding piezoelectric vibrator106to vibrate the piezoelectric vibrator106longitudinally. Consequently, the land105A of the vibrating plate105is vibrated to change the pressure in the pressure chamber107, and thereby the ink contained in the pressure chamber107is jetted in an ink particle through the nozzle hole108.

Thus, the connecting holes121are formed by etching the first base plate120such that portions of the etch terminating layer125are exposed, and the pressure chambers107, the ink inlet passages110and the ink storage chambers109are formed by etching second base plate122such that portions of the etch terminating layer125are exposed. Therefore, the depth of the connecting holes121is equal to the thickness of the first base plate, and the depths of the pressure chambers107, the ink inlet passages110and the ink storage chambers109are equal to the thickness of the second base plate122and hence the connecting holes121, the pressure chambers107, the ink inlet passages110and the ink storage chambers109can be highly accurately formed in desired depths, respectively. Partition walls defining the pressure chambers107are highly rigid and hence the pressure chambers107can be arranged in a high density. Since the ink-jet recording head does not have any components formed by electroforming on patterns and removed from the patterns, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost. The pressure chambers107and the connecting holes121can be accurately aligned with each other.

When the etch terminating layer125is a layer of a metal that is harder to be etched than the metals forming the first base plate120and the second base plate122, which are subjected to the etching processes, or when the first base plate120and the second base plate122are formed of a stainless steel or nickel, and the etch terminating layer125is formed of titanium, silver or gold, the etching of the first base plate120and the second base plate122can be surely terminated and etching can be properly ended. Furthermore, the passage unit101does not warp greatly and can be formed in a large size because the component members of the passage unit101have substantially equal linear expansion coefficients.

A passage unit included in an ink-jet recording head in a sixth embodiment according to the present invention will be described with reference toFIGS. 12A and 12B, in which parts like or corresponding to those of the ink-jet recording head shown inFIGS. 11A,11B and11C are denoted by the same reference characters and the description thereof will be omitted. This ink-jet recording head employs piezoelectric vibrators106A of a flexural vibration mode. A vibrating unit formed by sandwiching the piezoelectric vibrator106A between an upper electrode116and a lower electrode117is attached to the vibrating plate105included in the passage unit101.

The piezoelectric vibrators106A are driven for flexural vibrations by driving signals to change the pressure in the pressure chambers107to jet ink particles through the nozzle holes108. The ink-jet recording head in the sixth embodiment is the same in operation and effect as that in the fifth embodiment shown inFIGS. 11A,11B and11C.

A method of manufacturing the ink-jet recording head provided with the passage unit101shown inFIGS. 12A and 12Bwill be described with reference toFIG. 13. As shown inFIG. 13, (a), the first base plate120and the second base plate122are bonded to the etch terminating layer125to form a laminated plate-shaped member. The etch terminating layer125is an adhesive film. For example, an adhesive is applied to one surface of either the first base plate120or the second base plate122, and the first base plate120and the second base plate122are bonded together by the adhesive to form the laminated plate-shaped member.

As shown inFIG. 13, (b) and (c), the outer surfaces of the first base plate120and the second base plate122are coated with photosensitive, resin films124, respectively. The photosensitive resin films124are exposed to light in a connecting hole pattern123′ of the connecting holes121and a passage pattern123of the pressure chambers107, the ink inlet passages110and the ink storage chambers109, respectively. Then, the photosensitive resin films124are subjected to a developing process to form a mask having openings corresponding to the connecting holes121and a mask having openings corresponding to the pressure chambers107, the ink inlet passages110and the ink storage chambers109.

The photosensitive resin films124may be formed of any photosensitive resin, provided that the photosensitive resin is resistant to the corrosive effect of an etchant. A dry film photoresist is preferable because the dry film photoresist is capable of forming a comparatively thick film in a uniform thickness.

Subsequently, the laminated plate-shaped member is immersed in an etchant, the first base plate120and the second base plate122are connected to a positive electrode and a DC voltage is applied to the laminated plate-shaped member. Consequently, portions of the first base plate120corresponding to the openings in the connecting hole patter123′ and portions of the second base plate122corresponding to the openings in the passage pattern123are dissolved. As a result, the connecting holes121are formed in the first base plate120and the pressure chambers107, the ink inlet passages110and the ink storage chambers109are formed in the second base plate122as shown inFIG. 13, (d). The etchant may be any suitable etchant, such as a ferric chloride solution.

Then, the photosensitive films124are removed as shown inFIG. 13, (e), and portions of the etch terminating layer125remaining in the connecting holes121are removed by blasting, pressing or laser machining as shown inFIG. 13, (f). When necessary, portions of the etch terminating layer125exposed in the pressure chambers107, the ink inlet passages110and the ink storage chambers109are removed by blasting, laser machining or the like as shown inFIG. 13, (g). Removal of those portions of the etch terminating layer125is effective in preventing the adhesion of bubbles to those portions of the etch terminating layer125when the etch terminating layer125has a low ability to be wetted with the ink.

The recording head manufacturing method described with reference toFIG. 13etches through the first base plate120and the second base plate122such that the desired portions of the etch terminating layer125are exposed to form the connecting holes121, the pressure chambers107, the ink inlet passages110and the ink storage chambers109. Therefore, the depth of the connecting holes121is equal to the thickness of the first base plate120and the depths of the pressure chambers107, the ink inlet passages110and the ink storage chambers109are equal to the thickness of the second base plate122. Thus, those holes and chambers of the ink-jet recording head can be highly accurately formed. Partition walls defining the pressure chambers107are highly rigid and hence the pressure chambers107can be arranged in a high density. Since the ink-jet recording head does not have any components formed by electroforming on patterns and removed from the patterns, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost. The pressure chambers107and the connecting holes121can be accurately aligned with each other.

FIG. 14shows an ink-jet recording head in a seventh embodiment according to the present invention, which is similar to the ink-jet recording head shown inFIGS. 11A,11B and11C and hence parts like or corresponding to those of the ink-jet recording head shown inFIGS. 11A,11B and11C are denoted by the same reference characters and the description thereof will be omitted.

As shown inFIG. 14, the first base plate120is provided with the connecting holes121and auxiliary ink storage chambers109A formed by etching. The auxiliary ink storage chambers109A are additional ink storage chambers aligned with the ink storage chambers109formed in the second base plate122.

Thus, the ink-jet recording head in the seventh embodiment is provided additionally with the auxiliary ink storage chambers109A for the effective use of space. The ink storage chambers109and the auxiliary ink storage chambers109A provide a sufficiently large ink storage volume, reduce passage resistance and suppress crosstalk. The ink-jet recording head in the seventh embodiment is the same in operation and effect as that in the fifth embodiment shown inFIGS. 11A,11B and11C.

A method of manufacturing the ink-jet recording head shown inFIG. 14will be described with reference toFIG. 15.

As shown inFIG. 15, (a), the first base plate120and the second base plate122are bonded together by the etch terminating layer125to form a laminated plate-shaped member. As shown inFIG. 15, (b) and15(c), the outer surfaces of the first base plate120and the second base plate122are coated with photosensitive resin films124, respectively. The photosensitive resin films124are exposed to light in a connecting hole pattern123′ of the connecting holes121and a passage pattern123of the pressure chambers107, the ink inlet passages110and the ink storage chambers109, respectively. Then, the photosensitive resin films124are subjected to a developing process to form a mask having openings corresponding to the connecting holes121and a mask having openings corresponding to the pressure chambers107, the ink inlet passages110and the ink storage chambers109.

Subsequently, the laminated plate-shaped member is etched. Consequently, portions of the first base plate120corresponding to the openings in the connecting hole pattern123′ and portions of the second base plate122corresponding to the openings in the passage pattern123are dissolved. As a result, the connecting holes121and the auxiliary storage chambers109A are formed in the first base plate120and the pressure chambers107, the ink inlet passages110and the ink storage chambers109are formed in the second base plate122as shown inFIG. 15, (d).

Then, the photosensitive films124are removed as shown inFIG. 15, (e), and portions of the etch terminating layer125remaining in the connecting holes121and the auxiliary ink storage chambers109A are removed by blasting, pressing or laser machining as shown inFIG. 15, (f). When necessary, portions of the etch terminating layer125exposed in the pressure chambers107and the ink inlet passages110are removed by blasting, laser machining or the like as shown inFIG. 15, (g).

The recording head manufacturing method described with reference toFIG. 15is similar in steps to and the same in operation and effect as the recording head manufacturing method described with reference toFIG. 13, except that the former forms the auxiliary ink storage chambers109A in addition to the connecting holes121in the first base plate120.

FIG. 16is a longitudinal sectional view of an ink-jet recording head in an eighth embodiment according to the present invention, which is similar to the ink-jet recording head in the seventh embodiment shown inFIG. 14except that the former is provided with two passage plates104, and hence parts like or corresponding to those of the ink-jet recording head in the seventh embodiment are denoted by the same reference characters and the description thereof will be omitted.

Each passage plate104is formed by sandwiching an etch terminating layer125between a first base plate120and a second base plate122. The two passage plates104are superposed and bonded together with an epoxy adhesive, a two-sided adhesive tape or a polyolefin adhesive. Auxiliary ink storage chambers109A are formed in portions of the first base plates120corresponding to the ink storage chambers109formed in the second base plates122.

Since the ink-jet recording head in the eighth embodiment is provided with two second base plates122, the pressure chambers107and the ink storage chambers109can be formed in sufficiently large volumes. Since the first base plates120are provided with the auxiliary ink storage chambers109, i.e., additional ink storage chambers, space can be effectively used. Since the ink storage chambers109and the auxiliary ink storage chambers109A have a sufficiently large ink storage capacity, passage resistance can be reduced and crosstalk across the ink storage chambers109can be suppressed. The ink-jet recording head in the eighth embodiment is the same in operation and effect as the ink-jet recording heads shown inFIGS. 11A,11B,11C and14.

FIG. 17is a longitudinal sectional view of an ink-jet recording head in a ninth embodiment according to the present invention, which is similar to the ink-jet recording head in the seventh embodiment shown inFIG. 14and hence parts like or corresponding to those of the ink-jet recording head in the seventh embodiment are denoted by the same reference characters and the description thereof will be omitted.

The ink-jet recording head in the ninth embodiment has a metal layer105B formed on a surface of the vibrating plate105on the side of the pressure chambers107. Portions of the metal layer105B corresponding to the pressure chambers107and the ink storage chambers109are removed to form spaces respectively merging with the pressure chambers107and the ink storage chambers109. The second base plate122is bonded to the metal layer105B with an epoxy adhesive, a two-sided adhesive tape, a polyolefin adhesive or the like.

Since the spaces serving as part of the pressure chambers107and the ink storage chambers109formed in the second base plate122are formed in the metal layer105B, space can be effectively used. Since the ink storage chambers109have a sufficiently large ink storage capacity, passage resistance can be reduced and crosstalk across the ink storage chambers109can be suppressed. The ink-jet recording head in the ninth embodiment is the same in operation and effect as the ink-jet recording heads shown inFIGS. 11A,11B,11C and14.

FIG. 18shows an ink-jet recording head in a tenth embodiment according to the present invention, which is similar to the ink-jet recording head in the fifth embodiment shown inFIGS. 11A,11B and11C and hence parts like or corresponding to those of the ink-jet recording head in the fifth embodiment are denoted by the same reference characters and the description thereof will be omitted.

As shown inFIG. 18, the ink-jet recording head is provided with the nozzle plate103having the nozzle holes108which serve also as the connecting holes121shown inFIG. 11A, and is not provided with any member corresponding to the first base plate120shown inFIG. 11A. The nozzle plate103serves also as the first base plate120of the ink-jet recording head shown inFIG. 11A. The passage unit101of this ink-jet recording head has less component members than those in the foregoing embodiments and is advantageous in the possibility of accuracy improvement and cost reduction.

The ink-jet recording heads in the foregoing embodiments employs the etch terminating layer125which is made of an adhesive. When an etch terminating layer of a metal, such as titanium, gold, silver or the like is employed, the nozzle plate103and the second base plate122may be bonded together by, for example, a cladding process. Although the present invention has been described as applied to the ink-jet recording heads that jet ink particles by vibrations generated by the piezoelectric vibrators, the present invention is applicable also to ink-jet recording heads of a bubble jet system for the same operation and effect.

In a modification, the passage plate104is formed by processing a single sheet which is made of a single material, such as a stainless steel sheet. The front surface104aand the back surface104bof the passage plate104, i.e., a stainless steel sheet, may be etched in a depth equal to part of the thickness of the passage plate104by etching to form the connecting holes121, the pressure chambers107and the ink storage chambers109. Etch end point is determined on the basis of, for example, etching time.

An ink-jet recording head in an eleventh embodiment according to the present invention will be described with reference toFIGS. 19 to 23.

The ink-jet recording head shown inFIG. 19employs piezoelectric vibrators206of a longitudinal vibration mode and has a passage unit201provided with nozzle holes208and pressure chambers207, and a case202containing the piezoelectric vibrators206. The passage unit201is attached to the case202.

The passage unit201is formed by superposing and bonding together a nozzle plate203of a stainless steel provided with the nozzle holes208, and a passage plate204provided with pressure chambers207connected to the nozzle holes208, and ink storage chambers209for storing the ink to be supplied to the pressure chambers207, and including a vibrating plate205covering the open back ends of the pressure chambers207as shown inFIG. 23.

The passage plate204is formed by superposing a first base plate223provided with the pressure chambers207, a second base plate228provided with connecting holes219respectively connecting the pressure chambers207to the nozzle holes208, and the ink storage chambers209, and an ink supply plate224sandwiched between the first base plate223and the second base plate228. The ink supply plate224is provided with connecting holes219respectively connecting the pressure chambers207to the nozzle holes208, and ink inlet passages217through which the ink is supplied from the ink storage chambers209into the pressure chambers207.FIG. 21shows the positional relation between the pressure chambers207, the connecting holes219, the nozzle holes208and the ink inlet passages217.

The first base plate223is formed by bonding together a first etching plate220provided with the pressure chambers207formed by etching, a first etch terminating layer222serving as a vibrating plate205, and a second etching plate221having lands205A formed on the back surface of the vibrating plate205.FIG. 20shows the positional relation between the pressure chambers207and the lands205A.

The second base plate228is formed by bonding together a third etching plate225provided with the ink storage chambers209by etching as shown inFIG. 22, a fourth etching plate226provided with damping chambers218by etching for absorbing pressure variation in the ink storage chambers209, and a second etch terminating layer227sandwiched between the third etching plate225and the fourth etching plate226to serve as a damping flexible plate216.

Since the ink-jet recording head has the passage plate204formed by sandwiching the ink supply plate224between the first base plate223and the second base plate228, the ink storage chambers209are arranged on the side of the nozzle plate203with respect to the pressure chambers207so as to partly overlap the pressure chambers207. The damping chambers218are arranged on the side of the nozzle plate203with respect to the ink storage chambers209. InFIG. 19, indicated at232are vent holes formed in the nozzle plate203to open the damping chambers218into the atmosphere.

There are not any particular restrictions on materials forming the etching plates220,221,225and226, provided that the materials are properly rigid and are capable of being etched. Materials suitable for forming the etching plates220,221,225and226include stainless steels, nickel, aluminum, iron, copper and zinc. Stainless steels and nickel are preferable because these metals are excellent in corrosion resistance and comparatively easy to etch.

There are not any particular restrictions on materials for forming the etch terminating layers222and227provided that the etching processes to the etching plates220,221,225and226are terminated by the first and the second etch terminating layers222and227. Possible materials for forming the etch terminating layers222and227include thermosetting adhesives, such as epoxy adhesives, urethane adhesives, polyester adhesives and the like, and thermoplastic adhesives, such as polyimide adhesives and the like. These adhesives contain a volatile component in a small concentration and do not become porous after the volatile component has been volatilized. The etch terminating layers222and227may be films of a resin (polymer) or a metal that is harder to be etched than the material forming the etching plates220,221,225and226. The etch terminating layers222and227may be made of titanium, gold, silver or the like.

A plate for forming the first etching plate220of the first base plate223is etched through such that portions of the first etch terminating layer222are exposed to form the pressure chambers207. A plate for forming the second etching plate221is etched through such that portions of the first etch terminating layer222are exposed to form the lands205A. The first etch terminating layer222that has not been etched serves as the vibrating plate205.

A plate for forming the third etching plate225of the second base plate228is etched such that portions of the second etch terminating layer227are exposed to form the ink storage chambers209, and a plate for forming the fourth etching plate226is etched such that portions of the second etch terminating layer227are exposed to form the damping chambers218. The second etch terminating layer227which has not been etched serves as a damping film216.

The case202is formed of a synthetic resin and has spaces212extending between the upper and the lower surface thereof. The piezoelectric vibrators206are contained in the spaces212. The piezoelectric vibrators206of a longitudinal vibration mode have back ends fixed to base plates211attached to the case202and front ends fixed to lands205A formed on the lower surface of the vibrating plate205.

A driving signal produced by a driving circuit214is transmitted through a flexible wiring plate213to the corresponding piezoelectric vibrator206to vibrate the piezoelectric vibrator106longitudinally. Consequently, the land205A of the vibrating plate205is vibrated vertically, as viewed inFIG. 19to change the pressure in the pressure chamber207, and thereby the ink contained in the pressure chamber207is jetted in an ink particle through the nozzle hole208.

Since the ink storage chambers209are formed so as to overlap the pressure chambers207, the passage unit201can be formed in an area far smaller than that of the passage unit of the conventional ink-jet recording head, so that the ink-jet recording head can be formed in very small dimensions and is advantageous to increasing the level of integration. Since the passage unit201can be formed in a comparatively great thickness, the longitudinal rigidity of the piezoelectric vibrators206of a longitudinal vibration mode can be greatly increased and crosstalk attributable to the deformation of the passage unit201can be suppressed. Since the damping chamber218is formed on the side of the nozzle plate203with respect to the pressure chamber207, pressure variation in the ink storage chamber209can be absorbed to prevent crosstalk across the ink storage chamber209without entailing structural complication and enlargement.

The pressure chambers207and the lands205A are formed by etching the first etching plate220and the second etching plate221such that portions of the first etch terminating layer222corresponding to the pressure chambers207and regions around the lands205A are exposed. The ink storage chambers209and the damping chambers218are formed by etching the third etching plate225and the fourth etching plate226such that portions of the second etch terminating layer227corresponding of the ink storage chambers209and the damping chambers218are exposed. Therefore, the depths of the pressure chambers207, the ink storage chambers209, the damping chambers218and the thickness of the lands205A are equal to the thickness of the first etching plate220, the third etching plate225, the fourth etching plate226and the second etching plate221, respectively. Consequently, the pressure chambers207, the ink storage chambers209and the damping chambers218can be formed highly accurately in desired depths and the lands205A can be formed highly accurately in a desired thickness. Partition walls defining the pressure chambers207are highly rigid and hence the pressure chambers207can be arranged in a high density. Since the ink-jet recording head does not have any components formed by electroforming on patterns and removed from the patterns, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost.

The etch terminating layers222and227formed of an adhesive are capable of surely terminating etching and facilitate the fabrication of the passage plate204.

When the etch terminating layers222and227are formed of metals harder to be etched than those forming the etching plates220,221,225and226, or when the etching plates220,221,225and226are formed of a stainless steel or nickel and the etch terminating layers222and227are formed of titanium, silver or gold, the etching of the etching plate220,221,225and226can be surely terminated, the passage plate204does not warp greatly because the component members of the passage plate204have substantially equal linear expansion coefficients. The partition walls defining the pressure chambers207are highly rigid and hence the pressure chambers207can be arranged in a high density.

When the etch terminating layers222and227are resin films (films of polymeric materials) and the etch terminating layers222and227and the etching plates220,221,225and226are laminated with adhesive layers, the etching of the etching plates220,221,225and226can be surely terminated. Furthermore, the etch terminating layers222and227are highly strong and the etch terminating layers222and227are capable of properly functioning as the vibrating plate205and the damping film216, respectively.

A method of manufacturing the ink-jet recording head in the eleventh embodiment shown inFIG. 19will be explained.

FIGS. 24,25and26illustrate processes for making the first base plate223, the second base plate228and the passage unit201, respectively.

The process for making the first base plate223will be described with reference toFIG. 24. The first etching plate220, the second etching plate221and the first etch terminating layer222are laminated with the first etch terminating layer222sandwiched between the first etching plate220and the second etching plate221to form a laminated structure shown inFIG. 24, (a). The first etch terminating layer222is a resin film236having opposite surfaces coated with adhesive films237as shown inFIG. 27. The etching plates220and221are bonded to the opposite surfaces of the first etch terminating layer222by the adhesive films237.

Then, as shown inFIG. 24, (b), photosensitive resin films229are formed on the exposed surfaces of the first etching plate220and the second etching plate221. The photosensitive resin films229are exposed to light in patterns corresponding to the pressure chambers207and the regions around the lands205A. The exposed photosensitive resin films229are subjected to a developing process to form masks having openings arranged in patterns corresponding to those of the pressure chambers207and the regions around the lands205A, respectively, as shown inFIG. 24, (c).

The photosensitive resin films229may be formed of any photosensitive resin, provided that the photosensitive resin is resistant to the corrosive effect of an etchant. A dry film photoresist is preferable because the dry film photoresist is capable of forming a comparatively thick film in a uniform thickness.

The laminated structure provided with the masks is immersed in an etchant, the first etching plate220and the second etching plate221are connected to a positive electrode and a DC voltage is applied to the laminated structure. Portions of the etching plates220and221corresponding to the openings in the masks are etched to form the pressure chambers207and the lands205A as shown inFIG. 24, (d). There is not any particular restriction on the etchant and any suitable etchant, such as a ferric chloride solution, may be used.

Then, as shown inFIG. 24, (e), the photosensitive resin films229forming the masks are removed to obtain the first base plate223.

The process for making the second base plate228will be described with reference toFIG. 25. The third etching plate225, the fourth etching plate226and the second etch terminating layer227are laminated with the second etch terminating layer227sandwiched between the third etching plate225and the fourth etching plate226to form a laminated structure shown inFIG. 25, (a). The second etch terminating layer227, similarly to the first etch terminating layer222shown inFIG. 27, is a resin film236having opposite surfaces coated with adhesive films237.

Then, as shown inFIG. 25, (b), photosensitive resin films229are formed on the exposed surfaces of the third etching plate225and the fourth etching plate226. The photosensitive resin films229are exposed to light in patterns corresponding to patterns230of the ink storage chambers209, the damping chambers218and the connecting holes219. The exposed photosensitive resin films229are subjected to a developing process to form masks having openings arranged in patterns corresponding to the patterns230of the ink storage chambers209, the damping chambers218and the connecting holes219, respectively, as shown inFIG. 25, (c).

Portions of the third etching plate225and the fourth etching plate226corresponding to the openings of the patterns of the masks are etched to form the ink storage chambers209, the damping chambers218and the connecting holes219as shown inFIG. 25, (d).

Then, as shown inFIG. 25, (e), the photosensitive resin films229forming the masks are removed and portions of the second etch terminating layer227remaining in the connecting holes219are removed by blasting, pressing or laser machining to obtain the second base plate228as shown inFIG. 25, (f).

The nozzle plate203with the nozzle holes208and the vent holes232is formed by subjecting a plate to pressing, laser machining or the like. The ink supply plate224provided with the connecting holes219and the ink inlet passages217is formed by subjecting a plate to pressing, laser machining or the like.

Then, as shown inFIG. 26, the nozzle plate203, the second base plate228, the ink supply plate224and the first base plate223are superposed in that order and are laminated with adhesives to complete the passage unit201. The passage unit201is bonded to the case202containing the piezoelectric vibrators206to complete the ink-jet recording head shown inFIG. 19.

The method of manufacturing the ink-jet recording head according to the present invention forms the pressure chambers207, the lands205A, the ink storage chambers209and the damping chambers218by etching through the etching plates220,221,225and226such that portions of the etch terminating layers222and227corresponding to the pressure chambers207, the regions around the lands205A, the ink storage chambers209and the damping chambers218are exposed. Therefore, the depths of the pressure chambers207, the ink storage chambers209and the damping chambers218and the thickness of the lands205A are equal to the thicknesses of the corresponding etching plates220,221,225and226, respectively. Consequently, the pressure chambers207, the ink storage chambers209and the damping chambers218can be formed highly accurately in desired depths and the lands205A can be formed highly accurately in a desired thickness. Partition walls defining the pressure chambers207are highly rigid and hence the pressure chambers207can be arranged in a high density. Since the ink-jet recording head does not have any components formed by electroforming on patterns and removed from the patterns, the accuracy of the ink-jet recording head is not reduced and the ink-jet recording head is advantageous in cost.

FIG. 28shows an ink-jet recording head in a twelfth embodiment according to the present invention, which is similar to the ink-jet recording head in the eleventh embodiment shown inFIG. 19except that the former has the nozzle plate203, the second base plate228, the ink supply plate224and the first base plate223superposed in that order and laminated by adhesive films231A,231B and231C and hence parts like or corresponding to those of the ink-jet recording head in the eleventh embodiment shown inFIG. 19are denoted by the same reference characters and the description thereof will be omitted. The ink-jet recording head in the twelfth embodiment is similar in operation and effect to the ink-jet recording head shown inFIG. 19.

FIG. 29is a view of assistance in explaining a method of manufacturing the ink-jet recording head shown inFIG. 28. In this method, the adhesive film231C having openings corresponding to the pressure chambers207formed by punching is attached to the upper surface of the first base plate223. The adhesive film231A having openings corresponding to the damping chambers218formed by punching is attached to the upper surface of the second base plate228. The adhesive film231B having openings corresponding to the ink storage chambers209formed by punching is attached to the lower surface of the second base plate228.

The first base plate223provided with the adhesive film231C, the ink supply plate224, the second base plate228provided with the adhesive films231A and231B, and the nozzle plate203are superposed in that order and bonded together to form the passage unit201. Other steps of the method of manufacturing the ink-jet recording head shown inFIG. 28are the same as those of the method previously described with reference toFIGS. 24 to 27.

The method illustrated inFIG. 29prevents detrimental effects of adhesives protruding into spaces in which the ink is contained on ink jetting operations and failure in properly jetting ink particles due to bubbles that often form on adhesives protruded into spaces in which the ink is contained. The method is the same in operation and effect as the method illustrated inFIGS. 24 to 27.

Although each of the etch terminating layers222and227employed in the eleventh and the twelfth embodiment is the resin film236having opposite surfaces coated with the adhesive films237, the etch terminating layers222and227may be bonded to the etching plates220,221,225and226by, for example, a cladding process when the etch terminating layers222and227are formed of a metal, such as titanium, gold, silver or the like. When the etch terminating layers222and227are layers of adhesives, adhesives may be applied in films to the etching plates220,221,225and226and the etching plates220,221,225and226may be bonded together for the same operation and effect.