Abstract:
In a method of manufacturing a piezoelectric actuator there are provided a piece of piezoelectric material having piezoelectric bodies, a first piece of material having vibrational bodies, a second piece of material having movable bodies, and a third piece of material having pressurizing members. The first, second and third pieces of materials are superimposed over the piece of piezoelectric material to form a multilayered structure having piezoelectric actuators. The multilayered structure is cut to separate each of the piezoelectric actuators from one another.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of manufacturing a piezoelectric actuator. 
     2. Description of the Related Art 
     Conventionally, in a method of manufacturing individual piezoelectric actuators, a piezoelectric material is divided into various pieces each having a predetermined size, and then various such as a poling process and connection of various parts are performed for each piezoelectric piece of material. 
     Moreover, during miniaturization of the piezoelectric actuator, each structural part of the piezoelectric actuator is also miniaturized. Thus, in the conventional manufacturing method, it is difficult to treat miniaturized parts. Furthermore, since assembly of the piezoelectric actuator takes a long time, production efficiency becomes low and a manufacturing cost becomes high. 
     Further, since products of the piezoelectric actuators are packed individually, a manufacturing cost becomes high and unpacking of the package when it arrives at is destination is time consuming. 
     Furthermore, since the piezoelectric actuators are examined individually during quality examination before shipment, a time required for the examination becomes long. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method of manufacturing a piezoelectric actuator which has high production efficiency and is available to miniaturize the piezoelectric actuator. Also, an object of the present invention is to simply pack the piezoelectric actuator and to easily perform a quality examination before shipment. 
     To solve the above problems, there is provided a method of manufacturing a piezoelectric actuator characterized by including the steps of joining parts except for piezoelectric bodies to a piezoelectric material having a size that a plurality of piezoelectric actuators can be formed, so as to form the plurality of piezoelectric actuators, forming the piezoelectric material with a predetermined poling structure, and then dividing the piezoelectric material to form the plurality of piezoelectric actuators. 
     Here, joinings of the parts except for the piezoelectric bodies are performed by, for example, a step of forming electrodes having predetermined shapes on both surfaces of a piezoelectric material having a size that a plurality of piezoelectric actuators can be formed, a step of joining vibrating bodies to the piezoelectric material, a step of setting moving bodies so as to be actuated by vibration transmitted from the vibrating bodies, and a step of setting pressuring means for pressuring the moving bodies toward the vibrating bodies. After these steps are performed and the piezoelectric material is formed with a predetermined poling structure, the piezoelectric material is divided to manufacture the plurality of piezoelectric actuators. 
     Therefore, in comparison with a conventional method of manufacturing a piezoelectric actuator by performing various processings and joinings of various parts for each of the piezoelectric bodies divided, the number of steps can be greatly decreased. As a result, production efficiency is improved and a manufacturing cost can be decreased. 
     Also, a part sheet including a plurality of identical parts in predetermined positions is layered on the piezoelectric material to join at least one kind of the parts. As a result, the number of steps can be further decreased and miniaturization of each of the piezoelectric actuators can be sufficiently applied. 
     Also, after the step of joining the parts except for the piezoelectric bodies to the piezoelectric material so as to form the plurality of piezoelectric actuators and the step of poling the piezoelectric material are performed, the piezoelectric material may be transported to a place where the piezoelectric actuator is to be used, and divided into the plurality of piezoelectric actuators to use them in the place. 
     Therefore, since the plurality of piezoelectric actuators before the dividing are packed together, packing can be simplified and a manufacturing cost can be decreased. Also, a quality examination before shipment becomes easy. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings; 
     FIG. 1 is a cross sectional view of a piezoelectric actuator  1  manufactured by a manufacturing method of the present invention; 
     FIG. 2 is a plane view showing a piezoelectric material sheet formed with a shape; 
     FIG. 3 shows a dividing electrode pattern formed on one surface of the piezoelectric material sheet shown in FIG. 2; 
     FIG. 4 shows an entire surface electrode pattern formed on the other surface of the piezoelectric material sheet shown in FIG. 2; 
     FIGS. 5A and 5B show a vibrating body sheet, where FIG. 5A is a plane view and FIG. 5B is a cross-sectional view taken along line  5 B- 5 B′ in FIG. 5A; 
     FIGS. 6A and 6B show a supporting part and a holding part joined into a tip of the supporting part; 
     FIGS. 7A and 7B show a moving body sheet, where FIG. 7A is a plane view and FIG. 7B is a view taken along line  7 B- 7 B′ in FIG. 7A; 
     FIG. 8 shows a pressuring mechanism sheet; 
     FIGS. 9A and 9B show a plurality of piezoelectric actuators formed on the piezoelectric material sheet before dividing; 
     FIG. 10 is an explanatory diagram of steps in the method of manufacturing the piezoelectric actuator, to which the present invention is applied; 
     FIG. 11 shows a modification example of the piezoelectric material sheet; 
     FIG. 12 shows a modification example of the vibrating body sheet; 
     FIG. 13 shows a modification example of the moving body sheet; and 
     FIG. 14 shows a modification example of the pressuring mechanism sheet. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     Now, a structure of a piezoelectric actuator  1  manufactured by a manufacturing method of the present invention will be described. 
     FIG. 1 is a cross sectional view of the piezoelectric actuator  1  manufactured by the manufacturing method of the present invention. In FIG. 1, the piezoelectric actuator  1  is constructed of a piezoelectric body  11 , a vibrating body  14  which is joined on an upper surface of the piezoelectric body  11 , a plurality of protrusions  14   a  which are integrally provided on an upper surface of the vibrating body  14 , a supporting part  15  which is passed through the centers of the piezoelectric body  11  and the vibrating body  14 , a moving body  16  which is disposed to contact against the protrusions  14   a , a pressuring mechanism  17  whose a tip narrow portion (mentioned below) is fit to a groove portion  16   a  of the moving body  16 , which has functions for positioning the moving body  16  and supporting the supporting part  15  with rotation, and which presses the moving body  16  to the protrusions  14   a , and a holding part  18  for adjusting a pressure applied to the pressuring mechanism  17  and capping a tip of the supporting part  15 . 
     Next, the method of manufacturing the piezoelectric actuator will be described. 
     In the manufacturing method according to the present invention, although the details are mentioned below, a plurality of identical parts constituting the piezoelectric actuator  1  are formed as part sheets disposed on one surface. Also, a piezoelectric material sheet formed with a predetermined shape is performed with various processings such as poling processing, and each of the part sheets is joined onto the piezoelectric material sheet. Thus, the resultant piezoelectric material sheet with a plurality of piezoelectric actuators is manufactured, and then divided into each piezoelectric actuator  1 . 
     First, structures of the piezoelectric material sheet and the various part sheets, which are prepared to manufacture the piezoelectric actuators, will be described simply. 
     A piezoelectric material sheet  111  shown in FIG. 2 is formed with a size and a form such that nine piezoelectric actuators  1  can be formed. That is, the piezoelectric material sheet  111  has a size such that nine piezoelectric bodies  11  can be taken. Each of holes  11   a  into which the supporting part mentioned below is inserted is formed with penetration in the center of each of regions  11   b  as the piezoelectric bodies  11 . 
     As shown in FIG. 3, a dividing electrode pattern  121  is formed on one surface  111   a  of the piezoelectric material sheet  111 . Each of dividing electrode patterns  12  including electrode patterns  12   a  to  12   d  is formed on one surface of each of the piezoelectric bodies  11 . 
     Also, as shown in FIG. 4, an entire surface electrode pattern  131  is formed on the other surface  111   b  of the piezoelectric material sheet  111 . Thus, each of entire surface electrode patterns  13  is formed on the other surface of each of the piezoelectric bodies  11 . 
     Here, a process such as sputtering or a sol-gel method is used to form the dividing electrode pattern  121  and the entire surface electrode pattern  131 . The electrode patterns  121  and  131  can be also formed simultaneously. 
     A vibrating body sheet  141  shown in FIGS. 5A and 5B has nine vibrating bodies  14 . A position of each of the vibrating bodies  14  corresponds to a position of each of the piezoelectric bodies  11  of the piezoelectric material sheet  111 . Each of holes  14   b  into which the supporting part  15  mentioned below is inserted is formed with penetration in the center of each of the vibrating bodies  14 . In each of the vibrating bodies  14 , two protrusions  14   a  are formed in symmetric positions sandwiching the hole  14   b . Although the protrusions  14   a  are formed by depressing a portion around the protrusions  14   a  with cutting (see FIG.  5 B), further in order to decrease a load applied in dividing mentioned below, a region around the portion is depressed with cutting. 
     The supporting part  15  shown in FIG. 6B is constructed of three cylindrical portions  15   a ,  15   b  and  15   c  with different cross section areas. Here, the outside diameter of the cylindrical portion  15   a  is set to approximately equal to the diameter of a hole  17   b  of the pressuring mechanism  17  mentioned below. The outside diameter of the cylindrical portion  15   b  is set to approximately equal to the diameter of the hole  14   a  of the vibrating body  14 . The outside diameter of the cylindrical portion  15   c  is set to approximately equal to the diameter of the hole  11   a  of the piezoelectric body  11 . 
     Also, the holding part  18  shown in FIG. 6A is joined by fitting a concave portion  18   a  into a tip of the cylindrical portion  15   a  of the supporting part  15  in step S 9  mentioned below (see FIG.  10 ). 
     A moving body sheet  161  shown in FIGS. 7A and 7B has nine moving bodies  16 . A position of each of the moving bodies  16  corresponds to a position of each of the piezoelectric bodies  11  of the piezoelectric material sheet  111 . The three groove portions  16   a  are formed in each of the moving bodies  16  at regular intervals by a method such as etching or cutting. 
     A pressuring mechanism sheet  171  shown in FIG. 8 has nine pressuring mechanisms  17 . A position of each of the pressuring mechanisms  17  corresponds to a position of each of the piezoelectric bodies  11  of the piezoelectric material sheet  111 . Three tip narrow portions  17   a  which are fit into the groove portions  16   a  of each of the moving bodies  16  are formed in each of the pressuring mechanisms  17 . Each of the holes  17   b  into which the supporting part  15  is inserted is formed in the center of each of the pressuring mechanisms  17 . 
     Also, shafts provided in a jig (not shown) for assembly are inserted into holes  142 ,  162  and  172  which are formed in the vibrating body sheet  141 , the moving body sheet  161  and the pressuring mechanism sheet  171 , respectively. Each part sheet is assembled on the jig. 
     The above part sheets are joined onto the piezoelectric material sheet  111  in accordance with a flowchart of FIG. 10 mentioned below to simultaneously manufacture nine piezoelectric actuators  1  as shown in FIGS. 9A and 9B. 
     First, a piezoelectric material is processed to obtain the piezoelectric material sheet  111  with a predetermined shape (step S 1 ). 
     Next, the dividing electrode pattern  121  is formed on the surface  111   a  of the piezoelectric material sheet  111  (step S 2 ), and the entire surface electrode pattern  131  is formed on the other surface  111   b  of the piezoelectric material sheet  111  (step S 3 ). 
     Here, steps S 2  and S 3  may be performed simultaneously, or the electrode patterns  121  and  131  may be formed in the order reverse to the above. 
     Then, a predetermined voltage is applied to the electrode patterns  121  and  131  formed on both surfaces of the piezoelectric material sheet  111  to form the piezoelectric material sheet  111  (piezoelectric bodies  11 ) with a predetermined poling structure (step S 4 ). 
     Next, the piezoelectric material sheet  111  is joined to the vibrating body sheet  141  such that the holes  11   a  and  14   b  formed in each part sheet are overlapped each other (step S 5 ). 
     Then, the supporting parts  15  are joined to the piezoelectric material sheet  111  and the vibrating body sheet  141 , which are joined to each other (step S 6 ). 
     In this joining, the supporting parts  15  are inserted into the holes  11   a  of the piezoelectric material sheet  111  and the holes  14   b  of the moving body sheet  141  from the side of the other surface  111   b  of the piezoelectric material sheet  111 . Note that, since the inside diameter of each of the holes  14   b  is smaller than the outside diameter of the cylindrical portion  15   c  of each of the supporting parts  15 , the supporting parts  15  do not penetrate the vibrating body sheet  141 . 
     Next, the moving body sheet  161  is set on the vibrating body sheet  141  such that the moving bodies  16  contact the protrusions  14   a  of the vibrating bodies  14  (step S 7 ). 
     Then, the tip narrow portions  17   a  of the pressuring mechanisms  17  are fit to the groove portions  16   a  of the moving bodies  16  to set the pressuring mechanism sheet  171  onto the moving body sheet  161  (step S 8 ). Here, fitting of the tip narrow portions  17   a  to the groove portions  16   a  combines with inter-alignment. 
     Further, with a state that the pressuring mechanisms  17  are warped and pressured such that the moving bodies  16  are pushed to the protrusions  14   a  with a predetermined pressure, the holding parts  18  are joined onto the supporting parts  15  (step S 9 ). 
     Next, the piezoelectric: material sheet  111  is divided by dicing, blanking or the like, or by processing with an excimer laser (step S 10 ), so that nine piezoelectric actuators  1  shown in FIG. 1 are manufactured simultaneously. 
     As mentioned above, various processings and joinings (settings) of various parts are performed for the piezoelectric material sheet  111  (steps S 2  to S 9 ), and the resultant piezoelectric material sheet  111  is divided (step S 10 ) to manufacture the plurality of piezoelectric actuators  1 . Thus, the number of steps can be greatly decreased in comparison with a conventional method of manufacturing a piezoelectric actuator  1  by performing various processings and joinings of various parts for each of the piezoelectric bodies  11  divided. As a result, production efficiency is improved and a manufacturing cost can be decreased. 
     Also, even if parts are miniaturized, since joining of the parts is performed in part sheet unit, this joining is easier than that of a single part as the conventional method, so that working efficiency is improved. 
     Note that, the various part sheets are not limited to those in this embodiment. As shown in FIG. 1, it is not required that all the regions  11   b  on the piezoelectric material sheet  111  have the same size, and the regions  11   b  may have different sizes In the case where the regions  11   b  have different sizes, as shown in FIG. 12, the vibrating bodies  14  of the vibrating body sheet  141  are formed with a shape corresponding to each of the regions  11   b . Also, as shown in FIGS. 13 and 14, sizes and arrangements for the moving bodies  16  of the moving body sheet  161  and the pressuring mechanisms  17  of the pressuring mechanism sheet  171  are made corresponding to each of the regions  11   b.    
     Further, concrete details with respect to the number of the regions  11   b  of the piezoelectric material sheet  111 , electrode patterns formed on the piezoelectric material sheet  111 , the protrusions  14   a  formed in the vibrating bodies  14  or the like can be changed. 
     Also, in this embodiment, although the piezoelectric actuators are manufactured in number order from step  51  to step S 10 , steps S 1  to S 9  to be executed may be exchanged each other to the extent possible, and step S 10  may be executed last. 
     Also, dividing of the piezoelectric material sheet  111  (step S 10 ) may be performed in a place where the piezoelectric actuator  1  is to be used. In this case, since the plurality of piezoelectric actuators before the dividing are packed for transportation, packing can be simplified and a manufacturing cost can be decreased. Also, since a quality examination before shipment can be performed for a plurality of products together, the quality examination becomes easy. 
     Also, before the dividing, leads (lines and FPC boards) for applying voltage signals may be attached to the electrode patterns  12  and  13  formed in each of the regions  11   b  of the piezoelectric material sheet  111  (not shown). In this case as well, working efficiency is improved. 
     Although in the described embodiment the piezoelectric bodies  11  and the vibrating bodies  14  each have a rectangular shape, these components may have instead a circular shape or the like. 
     According to the present invention, the number of steps can be greatly decreased in comparison with a conventional method of manufacturing piezoelectric actuators individually by performing various processings and joinings of various parts for each of the piezoelectric bodies divided As a result, production efficiency is improved and a manufacturing cost can be decreased. 
     Also, by joining various parts as part sheets, the number of steps can be further decreased, and miniaturization of the piezoelectric actuator can be sufficiently applied. 
     Also, when a piezoelectric material is transported to a place where the piezoelectric actuator is to be used and divided into the plurality of piezoelectric actuators to use them in the place, since the plurality of piezoelectric actuators before the dividing are packed together, packing can be simplified. Also, a manufacturing cost can be decreased. Further, a quality examination before shipment becomes easy. 
     Although a manufacturing method of the present invention has been described in detail, the present invention is not limited to the above embodiment, and various improvements and modifications may be naturally made in the scope not departing from the gist of the present invention.