JP2629369B2 - Print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention displaces a movable element mounted on the other end of a piezoelectric element having one end supported on a base of a frame in a direction in which the piezoelectric element expands and contracts. The present invention relates to a print head configured to drive a print wire forward and backward through a motion conversion mechanism between the mover and a frame.

2. Description of the Related Art A print head of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 63-312852.

In this case, as shown in FIG.
The head body is mainly composed of the first and second substrates 102 and 103 joined to both end surfaces in the longitudinal direction of the support 101, and the second substrate 103 is provided with a nose portion 51 'for guiding the printing wire 11'. Can be Further, the frame 2 'of the printing unit PU' is tightened by the tightening bolt 104 using the inner surface of the first substrate 102 as an assembly reference plane F '. The second substrate 103 having the nose portion 51 'is provided with a fastening piece 105 protruding from the inner surface thereof, and the fastening piece 105 is provided with the piezoelectric element 1'.
A mounting hole 106 that is long in the direction of expansion and contraction is formed. And a tightening bolt 10 in a direction orthogonal to the direction of expansion and contraction of the piezoelectric element 1 '.
7 is inserted from the mounting hole 106 of the tightening piece 105, and the tightening bolt 107 is tightened to the mounting piece 108 protruding from the front end surface of the frame 2 ', whereby the first and second substrates 102, 103 To the frame 2 '.

[Problem to be Solved by the Invention] By the way, in the above-mentioned conventional one, the first substrate
Printing unit P with the inner side of 102 as assembly reference plane F '
Due to the structure for assembling the U 'frame 2', the distance L 'from the assembling reference plane F' to the tip end surface of the printing wire 11 'becomes long, and the tip end of the printing wire 11' tends to vary.
Furthermore, if there is a difference in the thermal expansion coefficient between the two members 2 'and 101 in the frame 2' and the column 101, the position of the tip of the printing wire 11 'is displaced back and forth by an amount corresponding to the difference, and printing is performed. There is a problem of adverse effects.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to attach a part of a front end surface of a frame to a substrate having a nose portion for guiding the print wire, and to attach the same frame as a reference surface, thereby making a print wire. It is an object of the present invention to provide a print head capable of preventing variations in the tip position of the print head.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, one end of a piezoelectric element in a direction of expansion and contraction is supported at a base of a frame, and a mover is attached to the other end of the piezoelectric element. A movement conversion mechanism for performing a tilting movement based on the displacement of the mover is brazed between the frame and the mover on the tip end surface side of the frame opposite to the base, and further moved forward and backward by the movement conversion mechanism. On a substrate having a nose portion that guides a driven printing wire so that the wire tip is disposed so as to project toward the tip face side opposite to the base of the frame, the frame has a part of the tip face. When the motion conversion mechanism is brazed between the motion conversion mechanism and an assembly reference surface that is mounted on the front end surface of the frame and that is in contact with the substrate, And a flow stopper for stopping the brazing material flowing toward the assembly reference plane.

[Operation] In the print head configured as described above, the frame is mounted on a substrate having a nose portion by using a part of the front end surface of the frame as a mounting reference surface, so that the nose guides the frame. The distance between the tip of the printing wire and the assembly reference plane can be made as short as possible, and the variation in the tip position of the printing wire can be reduced. In addition, even when the frame is expanded or contracted based on a temperature change, the tip position of the printing wire is not displaced.

Further, when brazing the motion conversion mechanism between the distal end surface of the frame and the mover, the brazing material flowing toward the assembly reference surface of the frame distal end surface is stopped at the flow stopper on the frame distal end surface. Therefore, it is possible to prevent the brazing material from flowing and adhering to the reference mounting surface of the frame.

An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a print head S mainly includes a substrate 50 having a nose portion 51 and a predetermined number of print units PU mounted on the substrate 50.

The substrate 50 is formed in a disk shape, and a concave portion 50a into which a part of the holder 40 for radially supporting each printing unit PU is fitted is formed on the back surface thereof. The substrate 50 is provided with a mounting hole 60 through which a tightening bolt 61 for tightening each printing unit PU on the front end surface of the frame 2 is inserted. Furthermore, a cylindrical nose portion is provided at the center of the surface of the substrate 50.
The nose portion 51 is provided with a predetermined number of guide plates 62 for guiding the printing wire 11 of each printing unit PU forward and backward.

As shown in FIG. 2, the printing unit PU includes a piezoelectric element 1, a frame 2, a mover 5, and a motion conversion mechanism 67.
The piezoelectric element 1 is composed of a laminated piezoelectric ceramic that expands and contracts when a voltage is applied. The frame 2 extends substantially parallel to the expansion and contraction direction of the piezoelectric element 1, and a base 3 for supporting one end of the piezoelectric element 1 in the expansion and contraction direction via a pair of wedge members 13 and 14 protrudes at one end thereof. Has been established.

A mover 5 is provided at the other end of the piezoelectric element 1 in the expansion and contraction direction, in a state facing the tip of the rising portion of the frame 2. A pair of leaf springs 6 and 7 are fixed to the opposing surfaces of the mover 5 and the frame 2 at one ends thereof by brazing. The leaf springs 6 and 7 face each other with a predetermined gap therebetween, and extend from the end faces of the frame 2 and the movable element 5 by a predetermined length in the direction in which the piezoelectric element 1 expands and contracts. At the other end (extended end) of both leaf springs 6, 7, a tilting body 8 is formed integrally with both leaf springs 6, 7. The movement conversion mechanism 6 is formed by the leaf springs 6 and 7 and the tilting body 8.
7 is configured. Further, a tilting arm 10 formed of a flat plate material is fixed to the tilting body 8 at a base thereof, and a printing wire 11 is fixed to a tip end of the tilting arm 10 at a base end thereof. The printing wires 11 of the printing units PU are inserted into the through holes of the guide plates 62 of the nose portion 51 so as to be able to advance and retreat.

A sub-frame 4 is integrally formed at one end of the base 3 of the frame 2. The sub-frame 4 extends along the other side of the piezoelectric element 1 (the side opposite to the frame 2) and to a position facing the mover 5.

A link between the extension end of the sub-frame 4 and the mover 5 forming a four-node parallel link mechanism for guiding the mover 5 in parallel with the direction of expansion and contraction based on the expansion and contraction of the piezoelectric element 1. The plate 16 is assembled.

In each printing unit PU configured as described above,
The leaf springs 6, 7, the tilt arm 10, and the printing wire 11 are assembled with a part of the front end surface of the frame 2 as an assembly reference plane F. Each printing unit PU is assembled with its reference surface F in contact with the back surface of the substrate 50.

On the front end surface of the frame 2, a brazing material caused by brazing of the leaf spring 6 flows toward the assembling reference plane F between the assembling reference plane F and the leaf spring 6 of the motion conversion mechanism 67. There is provided a flow stopper 70 for preventing the flow. In this embodiment, as shown in FIGS. 2 and 3, the flow stopper 70 protrudes from the front end surface of the frame 2 at a predetermined height. A stop surface 71 is provided, and an outer wall surface of the flow stop portion 70 is
The second mounting reference surface F2 is in contact with the inner peripheral surface of the concave portion 50a.

Further, the frame 2 has an insertion groove 82 through which the tightening bolt 61 is inserted from the assembly reference plane F, and a tightening bolt 61.
Is formed in a communication shape with a concave portion 83 into which a nut 84 is prevented from rotating and fitted.

In this embodiment, as shown in FIG.
An anti-vibration cover 90 covering the outer periphery of the print head S and made of an anti-vibration material such as rubber or synthetic resin is attached to the periphery of the substrate 50.

This embodiment is configured as described above. Therefore, the two leaf springs of the motion converting mechanism 67 are provided between the frame 2 and the mover 5.
When a part of the brazing material flows toward the assembling reference plane F at the front end surface of the frame 2 when the brazing materials 6 and 7 are fixed by brazing, as shown in FIG. The stop portion 70 is stopped at the flow stop surface 71 on the inner surface. For this reason, the flowing out brazing material A is prevented from adhering to the assembly reference plane F.

As described above, after the two leaf springs 6, 7 of the motion conversion mechanism 67 are brazed between the frame 2 and the mover 5, a pair of wedge members 13, 14 are interposed between the mover 5 and the frame 2. The printing unit PU is formed by assembling the piezoelectric element 1 via the.

Then, each printing unit PU is radially fitted into the holding groove of the holder 40 mounted on the back side of the substrate 50,
The printing wire 11 is inserted into a through hole of each guide plate 62 of the nose portion 51. Thereafter, the mounting reference surface F of the front end of the frame 2 of each printing unit PU is brought into contact with the back surface of the substrate 50, and the outer wall of the flow stopper 70 at the front end of the frame 2 is used as a second mounting reference surface F2. Under the state of being in contact with the circumferential surface of the concave portion 50a of the substrate 50, the tightening bolts 61 are respectively inserted from the mounting holes 60 of the substrate 50 as shown in FIGS. Each printing unit PU is assembled to the substrate 50 by passing the 61 through the insertion groove 82 of the frame 2 of each printing unit PU and tightening the nut to the nut 84 of the concave portion 83. At this time, since the brazing material A that has flowed out does not adhere to the assembling reference surface F at the front end surface of the frame 2, each printing unit PU is assembled with high precision to the substrate 50.

Further, the distance L from the assembly reference plane F to the tip of the printing wire 11 is made as short as possible because of the structure in which the tip end surface of the frame 2 is used as the assembly reference plane F and the board 50 having the nose portion 51 is assembled. The variation in the position of the tip of the printing wire 11 of each printing unit PU can be reduced. In addition, even when the frame 2 is expanded or contracted based on a temperature change, the position of the leading end of the printing wire 11 is not displaced.

Further, the print head S assembled as described above
In the above, when a voltage is applied between both electrodes of the piezoelectric element 1 of each printing unit PU, the piezoelectric element 1 extends by a predetermined length in the stacking direction, that is, the direction of arrow X in FIG. The mover 5 is displaced. Then, the leaf spring 7 on the mover 5 side is pushed up along the leaf spring 6 on the frame 2 side by receiving the displacement force of the mover 5, and both leaf springs 6, 7 are bent in a curved shape. In particular, the leaf spring 7 on the mover 5 side
Is largely bent toward the side leaf spring 6, a rotational moment is generated in the direction of arrow P at the base end of the tilting arm 10,
Thereby, the tilt arm 10 is tilted forward. Then, with the printing wire 11 at the tip of the tilt arm 10 being guided by a predetermined number of guide plates 15 of the nose part 51, the tip is advanced to the printing position.

When the application of the voltage to the piezoelectric element 1 is cut off, the piezoelectric element 1 contracts to its original state, and the mover 5 is displaced in the opposite direction by the elastic force based on the bending of the leaf springs 6 and 7. Is done. As a result, a rotational moment in the opposite direction is generated at the base end of the tilt arm 10, and the tilt arm 10 is tilted backward to the original position where the tilt arm 10 contacts the stopper 35 on the distal end surface of the subframe 4.

In the above-described embodiment, the brazing material flow stopping portion 70 is provided on the front end surface of the frame 2 at a predetermined height, but the present invention is not limited to this. For example, as shown in FIG. 5, a brazing material flow stopping portion 70 may be provided at a predetermined groove depth on the distal end surface of the frame 2 between the assembly reference surface F and the motion conversion mechanism 67. . However, in this case, when the leaf springs 6 and 7 of the motion conversion mechanism 67 are brazed between the frame 2 and the mover 5, the depth of the groove enough to stop the flowing brazing material at the flow stopper 70. Formed.

[Effects of the Invention] As described above, according to the present invention, since the frame is mounted on a substrate having a nose portion using a part of the front end surface of the frame as a mounting reference surface, a guide is provided on the nose portion. The distance between the tip of the printing wire and the reference surface for assembly can be made as short as possible, and the variation in the position of the tip of the printing wire can be reduced. Moreover, even when the frame is expanded or contracted based on the temperature change, the position of the tip of the printing wire is not displaced, so that printing defects can be prevented.

Further, when brazing the motion conversion mechanism between the distal end surface of the frame and the mover, the brazing material flowing toward the assembly reference surface of the frame distal end surface is stopped at the flow stopper on the frame distal end surface. For this reason, it is possible to prevent the brazing material from flowing and adhering to the mounting reference surface of the frame, to eliminate the need for removing the adhered brazing material, and to assemble the frame with high precision to the substrate. it can.

[Brief description of the drawings]

1 to 4 of the drawings show an embodiment of the present invention. FIG. 1 is a side sectional view showing the entire print head, FIG. 2 is a side view showing a print unit, and FIG. FIG. 4 is an exploded perspective view showing an assembling portion of the printing unit and the frame of the printing unit, FIG. 4 is an explanatory diagram showing an enlarged view of a brazing material stopping portion on the front end surface of the frame, and FIG. It is a side view which shows an example. FIG. 6 is a side sectional view showing a conventional print head. DESCRIPTION OF SYMBOLS 1 ... Piezoelectric element 2 ... Frame 3 ... Base 5 ... Movable element 6, 7 ... Leaf spring 8 ... Tilting body 50 ... Substrate 67 ... Motion conversion mechanism 70 ... Flow stop part F ... Group Reference surface PU …… Printing unit

Claims (1)

(57) [Claims] An end of the piezoelectric element in the direction of expansion and contraction is supported on the base of the frame, and a mover is mounted on the other end of the piezoelectric element. On the end face side of the frame opposite to the base,
A motion converting mechanism that performs a tilting motion based on the displacement of the mover is brazed between the frame and the mover, and a printing wire that is driven forward and backward by the motion converting mechanism has a wire tip of the frame. The frame is mounted on a substrate having a nose portion that guides so as to protrude toward the distal end surface side opposite to the base portion, with a part of the distal end surface being an assembly reference surface, On the tip end surface, between the mounting reference surface abutting on the substrate and the motion conversion mechanism, for stopping a brazing material flowing toward the mounting reference surface when brazing the motion conversion mechanism. A print head provided with a flow stopper.