Liquid ejecting apparatus

Provided is a liquid ejecting apparatus including a liquid ejecting head that ejects liquid through nozzle openings, and a wiper that sweeps a liquid ejection surface side of the liquid ejecting head, in which the liquid ejecting head includes a nozzle plate having the liquid ejection surface and a protection member that protrudes further on a liquid discharging side than the nozzle plate, and the wiper sweeps a surface of the protection member, which is an exterior surface of the protection member intended to be swept, toward the nozzle plate side, and then the wiper sweeps the liquid ejection surface so that the wiper moves away from the surface of the protection member and comes into contact with a portion between the nozzle openings on the nozzle plate and an end portion of the nozzle plate, which is located on an opposite side in a sweeping direction.

This application claims priority to Japanese Application No. 2013-052884, filed on Mar. 15, 2013, the entirety of which is incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a liquid ejecting apparatus equipped with a liquid ejecting head which ejects liquid through nozzle openings and particularly relates to an ink jet type recording apparatus equipped with an ink jet type recording head which ejects ink as liquid.

2. Related Art

An ink jet type recording apparatus in which ink as liquid is ejected to perform printing on a recording medium (an ejection receiving medium), such as a paper sheet and a recording sheet, has been known as a liquid ejecting apparatus in which liquid is ejected onto an ejection receiving medium, for example.

In the case of an ink jet type recording head mounted on the ink jet type recording apparatus described above, ink droplets are discharged, through nozzle openings, onto the ejection receiving medium. Thus, ink adhering to a vicinity of the nozzle opening which is formed on a liquid ejection surface and through which the ink droplets are ejected, or the solidified ink adhering to the vicinity of the nozzle opening causes a problem, such as an unstable ink-droplet discharge direction and discharging failure, for example, ink-droplet discharging failure.

For this reason, a liquid ejecting apparatus in which a wiper blade constituted by a rubber plate or the like sweeps a liquid ejection surface to clean ink, fluff, dust, or paper dust adhering to the liquid ejection surface has been proposed (see JP-A-2010-228151, for example).

Furthermore, there is a problem in that, even in a condition where the liquid ejection surface is wiped by the wiper blade, the ejection receiving medium is stained with ink, fluff, dust, or paper dust which adheres to a surface of a protection member, such as cover head, provided on the liquid ejection surface side, when the ejection receiving medium or the like comes into contact with the protection member.

For this reason, an ink jet recording apparatus in which a concave portion is provided in a portion between the protection member and the liquid ejection surface and a surface of the protection member and the liquid ejection surface are cleaned by a wiper blade has been proposed (see JP-A-2004-82699, for example).

However, there is a problem in that, in a case where a wiper comes into contact with an end portion of a nozzle plate when the wiper, such as a wiper blade, sweeps the liquid ejection surface, a liquid repellent film formed on a surface of the nozzle plate is likely to be separated from the end portion as a starting point.

In addition, there is a problem in that a lifespan of the wiper is shortened because the wiper is cut by a corner portion of the nozzle plate when the wiper comes into contact with the end portion of the nozzle plate.

Furthermore, there is a problem in that, in a case where the nozzle plate is constituted by a silicon single crystal substrate, the nozzle plate is likely to be damaged when the wiper comes into contact with the end portion of the nozzle plate.

Incidentally, in a case where the wiper skips over the nozzle opening and lands on the liquid ejection surface, unwiped remnants are left around the nozzle opening, and thus it is difficult to suppress discharging failure.

These problems are not limited to an ink jet type recording apparatus but are common to a liquid ejecting apparatus in which liquid other than ink is ejected.

SUMMARY

An advantage of some aspects of the invention is to provide a liquid ejecting apparatus in which a vicinity of a nozzle opening is reliably cleaned and in which a liquid repellent film is prevented from being separated owing to a sweeping operation by a wiper member and a lifespan of a wiper is prevented from being shorten.

According to an aspect of the invention, there is provided a liquid ejecting apparatus including a liquid ejecting head that ejects liquid through nozzle openings, and a wiper that sweeps a liquid ejection surface side of the liquid ejecting head, in which the liquid ejecting head includes a nozzle plate having the liquid ejection surface and a protection member that protrudes further on a liquid discharging side than the nozzle plate, and the wiper sweeps a surface of the protection member, which is an exterior surface of the protection member intended to be swept, toward the nozzle plate side, and then the wiper sweeps the liquid ejection surface so that the wiper moves away from the surface of the protection member and comes into contact with a portion between the nozzle openings on the nozzle plate and an end portion of the nozzle plate, which is located on an opposite side in a sweeping direction.

In this case, the wiper moves away from the protection member and lands in the portion between the nozzle openings on the nozzle plate and the end portion of the nozzle plate, which is located on the opposite side in the sweeping direction. Therefore, it is possible to prevent the wiper from coming into contact with an end surface of the nozzle plate, which is located on the opposite side in the sweeping direction. Thus, it is possible to prevent the liquid repellent film formed on the liquid ejection surface from being separated and to prevent the wiper from wearing out. In addition, the wiper lands on the liquid ejection surface and reliably sweeps the nozzle openings and the vicinities of the nozzle openings, and thus it is possible to suppress the discharging failure owing to unwiped remnants around the nozzle openings.

It is preferable that the nozzle plate be constituted by a silicon single crystal substrate. In this case, it is possible to perform processing with high density and high accuracy and to prevent the wiper from being damaged by shock caused when the wiper comes into contact with the nozzle plate.

It is preferable that the liquid ejecting head move, relative to the wiper, in a second direction perpendicular to a first direction which is an alignment direction of the nozzle openings through which the same kind of liquid is discharged. In this case, the liquid ejecting head is reduced in size, and thus it is possible to achieve a compact liquid ejecting apparatus.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, details of embodiments of the invention will be described.

FIG. 1is a perspective view illustrating the schematic configuration of an ink jet type recording apparatus as an example of a liquid ejecting apparatus according to Embodiment 1 of the invention.

An ink jet type recording apparatus I which is a liquid ejecting apparatus in Embodiment 1 is equipped with an ink jet type recording head unit1(also referred to as a head unit1, hereinafter) including a plurality of ink jet type recording heads II (also referred to as a recording head II, hereinafter), as illustrated inFIG. 1. An ink cartridge2constituting an ink feeding unit is detachably installed in the head unit1. A carriage3on which the head unit1is mounted is axially movably mounted on a carriage shaft5which is installed in an apparatus main body4. This head unit1discharges a black-ink composition and a color-ink composition.

In addition, a driving motor6is provided in a vicinity of one end portion of the carriage shaft5, and a first pulley6ahaving a groove on the outer circumference thereof is provided in a tip portion of a shaft of the driving motor6. Furthermore, a second pulley6bwhich corresponds to the first pulley6aof the driving motor6is rotatably provided in the vicinity of the other end portion of the carriage shaft5. A timing belt7which has an annular shape and is formed of an elastic material such as rubber is wound between the first pulley6aand the second pulley6b.

In addition, a driving force from the driving motor6is transmitted to the carriage3via the timing belt7, and thus the carriage3on which the head unit1is mounted moves along the carriage shaft5. In Embodiment 1, the movement direction of the carriage3is referred to as a main scanning direction. Meanwhile, a platen8is provided in the apparatus main body4so as to extend along the carriage3. This platen8is configured to be rotatable by a driving force from a paper feeding motor (not shown). A recording sheet S which is an ejection receiving medium (a recording medium), such as a paper sheet, fed by a paper feeding roller or the like, is wound around the platen8and transported. In Embodiment 1, the transport direction of the recording sheet S is referred to as a sub-scanning direction.

In addition, a wiper200which cleans a liquid ejection surface20aof the ink jet type recording head II in such a manner that the wiper200sweeps the liquid ejection surface20ais provided in a non-printing area which is an end portion in a movement direction of the carriage3and located on the side of the platen8. Details of the wiper200will be described below.

Here, an example of the ink jet type recording head mounted in an ink jet type recording apparatus will be described with reference toFIGS. 2 to 4. In addition,FIG. 2is an exploded perspective view of the ink jet type recording head, andFIG. 3is a plan view of a liquid ejection surface side of the ink jet type recording head.FIG. 4is a cross-sectional view taken along line IV-IV inFIG. 3, andFIG. 5is an enlarged view of a principal portion inFIG. 4.

The ink jet type recording head II of Embodiment 1 includes a plurality of members, such as a head main body11and a case member40, as illustrated in the accompanying drawings, and the plurality of members are joined to each other using an adhesive agent or the like. The head main body11of Embodiment 1 includes a flow-path forming substrate10, a communication plate15, a nozzle plate20, a protection substrate30, and a compliance substrate45.

Examples of material forming the flow-path forming substrate10constituting the head main body11include metal, such as stainless steel and Ni, a ceramic material represented by ZrO2or Al2O3, a glass ceramic material, and an oxide, such as MgO and LaAlO3. In Embodiment 1, the flow-path forming substrate10is constituted by a silicon single crystal substrate. One surface of the flow-path forming substrate10is subjected to anisotropic etching, and thus pressure generation chambers12which are partitioned by a plurality of partition walls are aligned along an alignment direction of a plurality of nozzle openings21through which ink is discharged. Hereinafter, this alignment direction is referred to as an alignment direction of the pressure generation chambers12or a first direction X. Furthermore, a plurality of rows in which the pressure generation chambers12are aligned in the first direction X are provided in the flow-path forming substrate10. In Embodiment 1, the number of the rows is two. Hereinafter, the row alignment direction where the plurality of the rows in which the pressure generation chambers12are aligned along the first direction X is referred to as a second direction Y.

Furthermore, in the flow-path forming substrate10, for example, a feeding path which applies a flow-path resistance to the ink flowing into the pressure generation chamber12and of which the size of opening is smaller than the size of the pressure generation chamber12may be provided in one end portion side of the pressure generation chamber12in the second direction Y.

In addition, the communication plate15is joined to one surface side of the flow-path forming substrate10. Furthermore, the nozzle plate20on which a plurality of nozzle openings21communicating with the respective pressure generation chambers12is bored is joined to the communication plate15.

A nozzle communication path16is provided in the communication plate15to cause the pressure generation chamber12to communicate with the nozzle opening21. The size of the communication plate15is greater than the size of the flow-path forming substrate10, and the size of the nozzle plate20is smaller than the size of the flow-path forming substrate10. The size of the nozzle plate20is relatively small, as described above, and thus it is possible to reduce the cost. In Embodiment 1, a surface of the nozzle plate20, on which the nozzle openings21are opened and from which ink droplets are discharged, is referred to as the liquid ejection surface20a.

In addition, a first manifold portion17and a second manifold portion18which constitute a part of a manifold100are provided in the communication plate15.

The first manifold portion17passes through the communication plate15in a thickness direction (a laminating direction of the communication plate15and the flow-path forming substrate10).

In addition, the second manifold portion18does not pass through the communication plate15in the thickness direction and is opened, on the communication plate15, toward a nozzle plate20side.

Furthermore, in the communication plate15, a feeding communication path19which communicates with one end portion of the pressure generation chamber12in the second direction Y is separately provided for each pressure generation chamber12. This feeding communication path19causes the second manifold portion18to communicate with the pressure generation chamber12.

Examples of material forming the communication plate15include metal, such as stainless steel and Ni, and ceramics, such as zirconium. In addition, it is preferable that the communication plate15be formed of material having the same linear expansion coefficient as that of the flow-path forming substrate10. In other words, in a case where the communication plate15is formed of a material of which a linear expansion coefficient is significantly different from that of the flow-path forming substrate10, when the communication plate15and the flow-path forming substrate10are heated or cooled, bending is caused due to a difference in the linear expansion coefficient between the flow-path forming substrate10and the communication plate15. In Embodiment 1, the communication plate15is formed of the same material as the flow-path forming substrate10, that is, a silicon single crystal substrate. As a result, it is possible to prevent the bending due to heating, a crack or separation due to heating, or the like from occurring.

In addition, the nozzle opening21is formed on the nozzle plate20to communicate with each pressure generation chamber12via the nozzle communication path16. In other words, the nozzle openings21through which the same types of liquids (inks) are ejected are aligned in the first direction X. Two rows in which the nozzle openings21are aligned in the first direction X are formed in the second direction Y.

Examples of material forming the nozzle plate20include metal, such as stainless steel (SUS), organic matter, such as polyimide resin, and a silicon single crystal substrate. Furthermore, the nozzle plate20is formed of a silicon single crystal substrate such that the linear expansion coefficient of the nozzle plate20is the same as that of the communication plate15. As a result, it is possible to prevent the bending due to heating or cooling, a crack or separation due to heating, or the like from occurring.

In addition, a liquid repellent film22having liquid repellency (ink repellency) is provided on the liquid ejection surface20aof the nozzle plate20. The liquid repellent film22is not particularly limited as long as the film has ink repellency (liquid repellency) with respect to ink discharged. Examples of the liquid repellent film22include a metal film containing a fluorine polymer and a metallic alkoxide molecular film having liquid repellency.

In addition, the liquid ejection surface20aof the nozzle plate20is directly subjected to eutectoid plating, and thus the liquid repellent film22which is constituted by a metal film containing a fluorine polymer can be formed.

In a case where a metallic alkoxide molecular film is used as the liquid repellent film22, it is possible to improve adherence properties of the liquid repellent film22, which is constituted by a molecular film, to the nozzle plate20by providing a base film, which is constituted by a plasma polymerized film, on the nozzle plate20side, for example. Furthermore, the base film constituted by a plasma polymerized film can be formed by polymerizing a silicone with an argon plasma gas. In the case of the liquid repellent film22constituted by a metallic alkoxide molecular film, a metallic-alkoxide polymerized molecular film can be formed as follows. First, a silane coupling agent, such as an alkoxysilane, is mixed with a solvent, such as a thinner, to form a metallic alkoxide solution. Then, the nozzle plate20is immersed in the metallic alkoxide solution. Incidentally, in a case where a metallic alkoxide molecular film is used as the liquid repellent film22, even when a base layer is provided in the liquid repellent film22, the liquid repellent film22can have a thickness smaller than a thickness of the liquid repellent film22which is constituted by a metal film containing a fluorine polymer and formed by a eutectoid plating method. Furthermore, it is advantageous in that an “abrasion resistance” and the liquid repellency can be improved. In this case, the “abrasion resistance” means that the liquid repellency is not deteriorated even when the liquid ejection surface20ais wiped to clean the surface. Needless to say, it is also possible to apply the liquid repellent film22constituted by a metal film containing a fluorine polymer, though the “abrasion resistance” and the “liquid repellency” are inferior.

Meanwhile, a diaphragm50is formed on a surface of the flow-path forming substrate10, which is opposite a surface facing the communication plate15. In Embodiment 1, an elastic film51which is provided on the flow-path forming substrate10and formed from oxide silicon and an insulator film52which is provided on the elastic film51and formed from zirconium oxide are provided as the diaphragm50. In addition, a liquid flow path, such as the pressure generation chamber12, is formed by performing anisotropic etching on one surface side (one surface side to which the nozzle plate20is joined) of the flow-path forming substrate10. The elastic film51is formed on the other surface side of the liquid flow path, such as the pressure generation chamber12.

In Embodiment 1, a first electrode60, a piezoelectric layer70, and a second electrode80are laminated on the insulator film52of the diaphragm50by a film forming method and a lithography method. These members constitute a piezoelectric actuator300. In this case, the piezoelectric actuator300means a portion including the first electrode60, the piezoelectric layer70, and the second electrode80. Generally, either one of electrodes of the piezoelectric actuator300is a common electrode. The other electrode and the piezoelectric layer70are formed by patterning, for each pressure generation chamber12. In this case, a portion that is constituted by either one of the electrodes and the piezoelectric layer70which are subjected to patterning and in which piezoelectric distortion is caused when voltage is applied to both electrodes is referred to as a piezoelectric active portion. In Embodiment 1, the first electrode60is used as a common electrode of the piezoelectric actuator300and the second electrode80is used as an individual electrode of the piezoelectric actuator300. However, there is no problem even when the common electrode and the individual electrode are reversed by reason of a driving circuit configuration or a wiring configuration. Furthermore, the first electrode60in the example described above continuously extends over the plurality of pressure generation chambers12, and thus the first electrode60functions as a part of the diaphragm. However, the configuration is not limited thereto. For example, only the first electrode60may function as the diaphragm, providing either one of the elastic film51or the insulator film52or neither of the two members.

In addition, the protection substrate30having substantially the same size as the flow-path forming substrate10is joined to the surface of the flow-path forming substrate10, which is located on the piezoelectric actuator300side. The protection substrate30has a holding portion31as a space for protecting the piezoelectric actuator300. In addition, a through-hole32which passes through in the thickness direction (the laminating direction of the flow-path forming substrate10and the protection substrate30) is formed in the protection substrate30. The other end of a lead electrode90, which is one opposite end connected to the second electrode80, extends to be exposed to the inside of the through-hole32. The lead electrode90and a wiring circuit substrate121on which a driving circuit120, such as a driving IC, is mounted are electrically connected in the through-hole32.

In addition, the case member40is fixed to the head main body11having a configuration described above. The case member40and the head main body11form the manifold100which communicates with the plurality of pressure generation chambers12. The shape of the case member40is substantially the same as the shape of the above-described communication plate15, when seen in a plan view. The case member40is joined to both the protection substrate30and the communication plate15described above. Specifically, a concave portion41having a width sufficiently large to accommodate the flow-path forming substrate10and the protection substrate30is provided on the protection substrate30side of the case member40. The opening size of the concave portion41is greater than the size of the surface of the protection substrate30, which is joined to the flow-path forming substrate10. Furthermore, in a state where the flow-path forming substrate10and the like are accommodated in the concave portion41, the opening of the concave portion41, which is located on the nozzle plate20side, is sealed by the communication plate15. Accordingly, a third manifold portion42is formed on an outer circumference portion of the flow-path forming substrate10, by the case member40and the head main body11. The manifold100of Embodiment 1 is constituted by the first manifold portion17, the second manifold portion18, which are formed in the communication plate15, and the third manifold portion42which is formed by the case member40and the head main body11.

Examples of material forming the case member40include resin and metal. Incidentally, the case member40can be mass-produced at low cost, by applying a method in which a resin material is molded.

In addition, the compliance substrate45is provided on the surface of the communication plate15, in which the first manifold portion17and the second manifold portion18are opened. This compliance substrate45seals openings of the first manifold portion17and the second manifold portion18, which are located on the liquid ejection surface20aside.

In Embodiment 1, the compliance substrate45described above has a sealing film46and a fixing substrate47. The sealing film46is constituted by a thin flexible film (a thin film which is formed of polyphenylene sulfide (PPS), stainless steel (SUS), or the like and of which a thickness is equal to or less than 20 μm). The fixing substrate47is formed of a hard material, such as metal represented by stainless steel (SUS) or the like. A part of the fixing substrate47, which faces manifold100, is completely removed in the thickness direction to form an opening portion48. Thus, one surface of the manifold100forms a compliance portion49which is a flexible portion sealed by only the sealing film46having flexibility.

An inlet44which communicates with the manifold100and through which the ink is supplied to the manifold100is provided in the case member40. Furthermore, a connection port43which communicates with the through-hole32of the protection substrate30and into which the wiring circuit substrate121is inserted is provided in the case member40.

In the ink jet type recording head II configured as above, when ejecting the ink, the ink is introduced from the ink cartridge2through the inlet44and the flow path from the manifold100to the nozzle openings21is filled with the ink. Then, voltage is applied, in response to a signal from the driving circuit120, to each piezoelectric actuator300corresponding to the pressure generation chamber12, and thus the piezoelectric actuator300and the diaphragm50are flexibly deformed. As a result, the pressure in the pressure generation chamber12increases, and thus ink droplets are ejected through the predetermined nozzle openings21. In the ink jet type recording head II of Embodiment 1, a path from the inlet44to the nozzle openings21is referred to as a liquid flow path. In other words, the liquid flow path is constituted by the inlet44, the manifold100, the feeding communication path19, the pressure generation chamber12, the nozzle communication path16, and the nozzle openings21.

In addition, a cover head130as a protection member of Embodiment 1 is provided on the liquid ejection surface20aside of the head main body11. The cover head130is joined to a surface side of the compliance substrate45, which is opposite the communication plate15side. The cover head130seals a space in the compliance portion49, which is located on a side opposite the flow path (the manifold100). An exposure opening portion131through which the nozzle openings21are exposed is provided in the cover head130. The exposure opening portion131of Embodiment 1 has a size sufficiently large to allow the nozzle plate20to be exposed, that is, the same size as the opening formed in the compliance substrate45.

In Embodiment 1, an end portion of the cover head130bends from the liquid ejection surface20aside to cover a side surface (a surface intersecting with the liquid ejection surface20a) of the head main body11.

The cover head130of Embodiment 1 protrudes, in an ink (liquid) discharge direction, further on the recording sheet S side than the liquid ejection surface20aof the nozzle plate20. It is difficult for the recording sheet S to come into contact with the nozzle plate20, because the cover head130protrudes further on the recording sheet S side than the liquid ejection surface20a, as described above. Thus, it is possible to prevent the nozzle plate20from being deformed or separated due to the recording sheet S contacting with the nozzle plate20.

Furthermore, a liquid repellent film having liquid repellency may be provided on a surface of the cover head130, which is located on the same side as the liquid ejection surface20a, that is, a surface located on a side opposite the compliance substrate45, as similar to the nozzle plate20.

In Embodiment 1, a gap between the nozzle plate20and the exposure opening portion131of the cover head130is filled with a filler material132. In the nozzle plate20side, the filler material132is formed in a position (in terms of a direction opposite a liquid ejecting direction) lower than the liquid ejection surface20a. Also, in the cover head130side, the filler material132is formed in a position lower than the surface of the cover head130. Thus, it is possible to prevent the filler material132from coming into contact with the wiper200and being separated to cause a foreign matter, when the wiper200sweeps the surface of the cover head130and the liquid ejection surface20aof the nozzle plate20. Details of this effect will be described below. Furthermore, the filler material132is provided as described above, and thus it is possible to prevent the ink, which stays in a portion between the nozzle plate20and the cover head130, from dropping onto the recording sheet S at an unexpected timing and staining the recording sheet S.

A material forming the filler material132is not particularly limited as long as the material has a liquid resistance. Examples of the material forming the filler material132include an adhesive agent and the like. Furthermore, the filler material132may be part of an adhesive agent which is used for adhering the cover head130to the compliance substrate45, for example.

The ink jet type recording head II described above is mounted to the ink jet type recording apparatus I in a state where the second direction Y is parallel to a main scanning direction which is a movement direction of the carriage3.

Here, details of the wiper200for cleaning the liquid ejection surface20aof the ink jet type recording head II will be described with reference toFIGS. 1 to 6C.FIGS. 6A to 6Care cross-sectional views of principal portions for illustrating a cleaning operation.

The wiper200of Embodiment 1 has a blade portion201which is constituted by a plate-shaped member formed from an elastic material, such as rubber or an elastomer, and a base portion202to which the blade portion201is fixed.

In the ink jet type recording apparatus I, the base portion202is disposed in an area, namely, a non-printing area, outside an area within which the ink lands on the recording sheet S and is located at a position opposite the liquid ejection surface20a, as illustrated inFIG. 1. The base portion202may be configured to be movable in an ink-droplet discharge direction, for example.

A base end portion of the blade portion201is fixed to the base portion202such that a tip of the blade portion201is set to be a free end. In addition, the blade portion201is disposed in a state where a plane direction is parallel to the first direction X and in a state where the tip, that is, the free end, protrudes toward the liquid ejection surface20a.

Furthermore, the blade portion201of Embodiment 1 is disposed in a state where the blade portion201bends with respect to a straight line in the first direction X such that one surface of the blade portion201has a concave portion shape.

A length of the blade portion201is set to be longer than a length of the row, in which the nozzle openings21formed on the nozzle plate20are aligned, in the first direction X. In Embodiment 1, a length of the blade portion201in the first direction X is set to be longer than a length of the cover head130in the first direction X. Accordingly, the blade portion201can sweep the entire surface of the cover head130and the liquid ejection surface20a.

The wiper200wipes the liquid ejection surface20ain such a manner that the blade portion201moves in the second direction Y relative to the ink jet type recording head II, and thus the tip of the blade portion201sweeps the liquid ejection surface20a.

In Embodiment 1, the relative movement of the blade portion201(the wiper200) to the ink jet type recording head II is performed in such a manner that the carriage3on which the ink jet type recording head II is mounted moves in the main scanning direction (the second direction Y). Needless to say, the relative movement of the wiper200to the ink jet type recording head II is not limited to an operation in which the carriage3moves. The relative movement may be operated as follows. A movement unit, for example, may be installed to move the wiper200in the main scanning direction (the second direction Y), and the movement unit may cause the wiper200to move in a state where the carriage3on which the ink jet type recording head II is mounted is stopped. Alternatively, the wiper200may move in a sub-scanning direction relative to the ink jet type recording head II such that the blade portion201sweeps the liquid ejection surface20ain the first direction X.

The blade portion201of the wiper200configured as above sweeps the surface of the cover head130, and then sweeps the liquid ejection surface20aof the nozzle plate20.

Specifically, the ink jet type recording head II moves in the second direction Y relative to the wiper200, and thus the tip of the blade portion201sweeps the surface (on the liquid ejection surface20aside) of the cover head130, as illustrated inFIG. 6A. As a result, the wiper200wipes off ink (liquid), fluff, dust, or paper dust adhering to the surface of the cover head130.

Subsequently, when the ink jet type recording head II further moves in the second direction Y relative to the wiper200, the tip of the blade portion201moves away from an end portion of the cover head130, which is located on the nozzle plate side, as illustrated inFIG. 6B, and the tip of the blade portion201lands in an area B on the liquid ejection surface20a, which is an area between the nozzle opening21of the nozzle plate20and an end portion of the nozzle plate20, which is located on an opposite side in a sweeping direction (the second direction Y in Embodiment 1), as illustrated inFIG. 6C. In this case, the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction, means the end portion of the nozzle plate20, which is adjacent to a side of an area on the cover head130, which has been swept by the blade portion201. The nozzle opening21defining the area B is one of the nozzle openings21, which is located at a position closest to the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction. More specifically, the nozzle opening21defining the area B means an edge of the opening, which is adjacent to the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction. In other words, the area B is an area between the edge of the nozzle opening21located at the position closest to the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction, and the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction of the nozzle plate20. The area B does not include the edge of the nozzle opening21and an end surface of the nozzle plate20.

Next, the blade portion201lands in the area B of the liquid ejection surface20a, and then the ink jet type recording head II moves in the second direction Y relative to the wiper200, as illustrated inFIG. 6C. As a result, the blade portion201passes through an upper portion of the nozzle opening21, and thus the vicinity of the nozzle opening21is cleaned. Subsequently, a surface of the cover head130, which is located on a sweep-direction side in the second direction Y, is swept after the liquid ejection surface20ais cleaned. Thereby, the surface of the cover head130is cleaned, and then a cleaning operation is finished.

The blade portion201sweeps the surface of the cover head130, and then the blade portion201lands in the area B of the liquid ejection surface20aon the nozzle plate20and cleans the liquid ejection surface20a, as described above. Thus, it is possible to prevent the blade portion201from coming into contact with the end surface (a corner portion) of the nozzle plate20. As a result, it is possible to suppress the separation of the liquid repellent film22which is formed on the liquid ejection surface20aon the nozzle plate20.

Furthermore, the blade portion201lands in the area B of the liquid ejection surface20a, and this makes it possible to prolong a lifespan of the blade portion201. Incidentally, when the blade portion201sweeps the corner portion of the nozzle plate20, the blade portion201is cut by the corner portion of the nozzle plate20.

Furthermore, the blade portion201lands in the area B of the liquid ejection surface20a, and thus it is possible to prevent the nozzle plate20from being damaged, even in a case where the nozzle plate20is formed of brittle material, such as a silicon single crystal substrate. In other words, in a case where the nozzle plate20is formed of brittle material, such as a silicon single crystal substrate, the nozzle plate20is likely to be damaged by shock caused when the blade portion201comes into contact with the end surface of the nozzle plate20.

The blade portion201lands in the area B of the liquid ejection surface20a, and then the blade portion201can sweep the nozzle opening21and the vicinity of the opening. Thus, it is possible to reliably remove ink or a foreign matter adhering around the nozzle opening21. Incidentally, in a case where the blade portion201skips over the nozzle opening21and lands on the liquid ejection surface20a, the foreign matter around the nozzle opening21is not removed and thus unwiped remnants are left. This can cause ink-droplet discharging failure or the like.

For causing the blade portion201to land in the area B between the nozzle opening21and the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction, it is necessary to appropriately adjust a width of the area A, a width of the area B, a level difference between the liquid ejection surface20aand the cover head130, a movement speed of the blade portion201relative to the ink jet type recording head, material properties (an elastic property) of the blade portion201, a push-in amount of the blade portion201or the like.

Here, simulation results of a landing position of the blade portion201, in which various parameters are changed, are illustrated inFIG. 7.FIG. 7is a graph illustrating simulation results of landing positions of the wiper200.

As illustrated inFIG. 7, when the level difference between the cover head130and the blade portion201is set to be 350 μm, the blade portion201lands in the area B, in any case where the movement speed of the blade portion201is set to be 30 mm/s or 60 mm/s and the push-in amount of the blade portion201is set to be 1.8 mm or 1.3 mm.

Similarly, when the level difference between the cover head130and the blade portion201is set to be 240 μm, the blade portion201lands in the area B, in any case where the movement speed of the blade portion201is set to be 30 mm/s or 60 mm/s and the push-in amount of the blade portion201is set to be 1.8 mm or 1.3 mm.

However, when the level difference between the cover head130and the blade portion201is set to be 100 μm, the blade portion201lands not in the area A but in the area A, in any case where the movement speed of the blade portion201is set to be 30 mm/s or 60 mm/s and the push-in amount of the blade portion201is set to be 1.8 mm or 1.3 mm.

In a case where the area B of the liquid ejection surface20aor the area A between the liquid ejection surface20aand the cover head130is wide, the size and the cost of the ink jet type recording head are increased. Thus, the size of the ink jet type recording head can be reduced by setting the widths of the area A and area B to be as narrow as possible. Specifically, the wiper200of Embodiment 1 sweeps the liquid ejection surface20ain such a manner where the wiper200moves in the second direction Y relative to the liquid ejection surface20a, and thus the following problem is caused in a case where the area B between the nozzle opening21and the end portion of the nozzle plate20, which is located on the opposite side in the sweeping direction, is wide. A distance between the nozzle rows is set to be great when a plurality of the ink jet type recording heads II are mounted. Accordingly, it is preferable that the width of the area B be set to be as narrow as possible.

The blade portion201cleans the surface of the cover head130, which is located on the liquid ejection surface20aside, as described above. Thus, it is possible to prevent the foreign matter, such as ink, adhering to the cover head130from staining the recording sheet S. Furthermore, the blade portion201lands in the area B of the liquid ejection surface20aafter cleaning the cover head130, and thus it is possible to suppress the separation of the liquid repellent film22by the blade portion201. In addition, the blade portion201lands in the area B, and then the blade portion201can reliably clean the foreign matter in the vicinity of the nozzle opening21. Thus, it is possible to prevent the discharge failure owing to unwiped remnants from being caused. Furthermore, the blade portion201does not sweep the end surface of the nozzle plate20, and thus it is possible to prevent the nozzle plate20from being damaged and to prevent the blade portion201from wearing out.

Other Embodiments

Hereinbefore, an embodiment of the invention is described. However, the basic configuration of the invention is not limited thereto.

In Embodiment 1 described above, a wiper which has the blade portion201constituted by a plate-shaped member and the base portion202is exemplified as the wiper200, for example. However, without being limited thereto, a porous material, such as a sponge, or non-woven fabric, for example, may be used as the wiper200to sweep the liquid ejection surface20a. In other words, the material or the shape of the wiper200is not limited as long as the wiper200sweeps the liquid ejection surface20aand cleans the liquid ejection surface20a, for example.

In Embodiment 1, the blade portion201of the wiper200sweeps the liquid ejection surface20aon the ink jet type recording head II in such a manner that the wiper200moves in the second direction Y relative to the liquid ejection surface20a. However, the sweeping movement is not particularly limited thereto and the wiper200may sweep the liquid ejection surface20ain such a manner that the wiper200moves in the first direction X relative to the liquid ejection surface20a.

In Embodiment 1 described above, one cover head130(the exposure opening portion131) is provided for each head main body11. However, the configuration is not particularly limited thereto and one cover head may be provided for two or more head main bodies11, for example. In this case, the exposure opening portion131may be provided in the cover head for each head main body11, and a plurality of the head main bodies11may be exposed through one exposure opening portion131.

In the ink jet type recording apparatus I of Embodiment 1 described above, the ink jet type recording head II (the head unit1) moves in the main scanning direction in a state where the ink jet type recording head II is mounted on the carriage3. However, the configuration is not particularly limited thereto and this invention can be applied to a so-called line-type recording apparatus in which the ink jet type recording apparatus I is fixed and only the recording sheet S, such as a paper sheet, moves in the sub-scanning direction to perform printing, for example.

In the example described above, the ink jet type recording apparatus I has a configuration in which the ink cartridge2as a liquid storage unit is mounted on the carriage3. However, the configuration is not particularly limited thereto. The liquid storage unit, such as an ink tank, may be fixed to the apparatus main body4and the storage unit and the ink jet type recording head II may be connected through a feeding tube, such as a tube, for example. Furthermore, the liquid storage unit may not be mounted on the ink jet type recording apparatus.

In the description of Embodiment 1, the piezoelectric actuator300of a thin film type is used as a pressure generation unit for changing the pressure in the pressure generation chamber12. However, the pressure generation unit is not limited thereto. A thick-film type piezoelectric actuator which is formed by, for example, a greensheet-paste method or a longitudinal-oscillation type piezoelectric actuator which is formed by laminating a piezoelectric material and an electrode forming material on each other and which expands and contracts in an axial direction can be used as the pressure generation unit, for example. Furthermore, a unit in which a heater element is provided in a pressure generation chamber and which causes liquid droplets to be discharged through nozzle openings by using bubbles generated by the heating of the heater element, or a so-called electrostatic actuator in which static electricity is generated between a diaphragm and an electrode and which causes the diaphragm to be deformed and liquid droplets to be discharged through nozzle openings by using the electrostatic force can be used as the pressure generation unit, for example.

In the description of the embodiment, the ink jet type recording apparatus equipped with the ink jet type recording head is used as an example of the liquid ejecting apparatus. However, the present invention is intended to be applied to general types of liquid ejecting apparatuses. The present invention can also be applied to a liquid ejecting apparatus equipped with a liquid ejecting head which ejects liquid other than ink. Other examples of the liquid ejecting head include various types of recording heads which are applied to image recording apparatuses, such as a printer, a coloring material ejecting head used to manufacture a color filter for a liquid crystal display or the like, an electrode material ejecting head used to form an electrode for an organic EL display, a field emission display (FED) or the like, a bio-organic material ejecting head used to manufacture a biochip, or the like. The present invention can be applied to a liquid ejecting apparatus equipped with the liquid ejecting head described above.