JPH05124226A - Piezoelectric element drive-type printing head - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric element drive-type printing head having no possibility that the vibration of a piezoelectric element may cause a lead wire to be cut at a soldered part of a holder as a junction of the lead wire from the piezoelectric element or cause a power supply wire on a wiring board to be disconnected from a circuit. CONSTITUTION:A title head is provided with a holder 33 as a junction of lead wires 31, 32 led out of each piezoelectric element 11. The holder 33 is provided with a claw part 33a, which is held on a leg part of each frame 12 by a spring force. In this held state, a gap between the holder 33 and the frame 12 is determined to be sufficiently larger than an amplitude of the frame 12 when the piezoelectric element 11 is driven.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits expansion and contraction of a piezoelectric element due to voltage application to a print wire by a motion transmission mechanism,
The present invention relates to a piezoelectric element drive type print head that prints characters and figures on a print medium such as paper.

[0002]

2. Description of the Related Art Conventionally, this type of print head is
As disclosed in Japanese Patent Application Laid-Open No. 60-969, a plurality of piezoelectric elements are mounted on a mounting member (frame) to form a unit, and these units are arranged and supported by a holding member such as a pedestal. Have. And, although not shown in the above publication, usually, the other end side of the lead wire whose one end side is connected to both electrodes of each piezoelectric element is connected to a relay holder or the like fixed to each piezoelectric element. It is conceivable to relay this holder and connect it to the terminal wire. Further, the other end side of the terminal wire connected to this holder is led out to the wiring board supporting the power supply line corresponding to each piezoelectric element, connected by soldering or the like on the wiring board, and connected to each holder. It is considered that the lead wire and the terminal wire are connected and fixed by soldering or the like.

[0003]

However, the terminal wire connected to the holder as described above is led out to the wiring board supporting the power supply wire corresponding to each piezoelectric element and connected by soldering or the like. In the configuration, since each holder is fixed to the piezoelectric element, the vibration of the piezoelectric element is directly transmitted to each holder, the terminal wire, and the wiring board to vibrate them. Due to this vibration, there is a problem that the lead wire is broken at the soldered portion of each holder, the terminal wire is broken at the soldered portion, and the circuit connection of the feeder line on the wiring board is broken. The present invention has been made in order to solve the above-mentioned problems, and by virtue of the structure capable of reducing the vibration of each holder and terminal wire that reaches the wiring board, the soldered portion of each holder An object of the present invention is to provide a piezoelectric element drive type print head in which lead wires are not cut and circuit connections of power supply lines on a wiring board are not cut.

[0004]

In order to achieve this object, the present invention provides a print head using a plurality of columnar piezoelectric elements which expand and contract in the longitudinal direction when a voltage is applied.
A frame for supporting each piezoelectric element, a motion transmission mechanism for transmitting the expansion and contraction of the piezoelectric element to a printing wire that prints on the print medium, and a unit holding member for arranging and supporting the frame on which the piezoelectric elements are supported. A holder for relaying the lead wire derived from each of the piezoelectric elements, and a wiring board for supporting a power supply line that is electrically connected to the lead wire and supplies power from the outside, and the mounting position of the holder is to be attached to the frame. It is attached so as to be movable with respect to the position.

[0005]

According to the above construction, the holder for relaying the lead wire led out from each piezoelectric element is movably attached to the frame supported by each piezoelectric element, so that the holder is arranged in the expansion / contraction direction of the piezoelectric element. It is possible to move freely, and the vibration of the piezoelectric element is absorbed and it is difficult to transmit it to the holder.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a side sectional view of the print head, FIG.
Shows a side view of the printing unit. In FIG. 1, a head body 1 includes a plurality of (for example, 24) printing units 2
A disk-shaped unit holding member 4 to which an annular support ring 3 for radially positioning and supporting the plurality of printing units 2 is fixed, and a cylindrical cup-shaped cover 5 covering the outer periphery of the printing unit 2. It is composed mainly of.
On the front side surface of the disk-shaped unit holding member 4, a hollow nose portion 8 in which a predetermined number of guide plates 7 for moving and guiding the printing wires 6 of each printing unit 2 are provided is projected. .. Further, the support ring 3 is fastened to the inner surface side of the unit holding member 4 by fastening bolts (not shown). Further, the support ring 3 is fixed to the unit holding member 4 in a non-contact state by sandwiching an elastic body or the like with a bolt or the like.

Each printing unit 2 is, as shown in FIG.
The piezoelectric element 11 that expands and contracts when a voltage is applied is attached to the frame 12
The piezoelectric element 1 is supported on the frame 12.
A motion transmission mechanism 13 for enlarging the expansion and contraction of 1 and transmitting it to the print wire 6 is disposed and supported. The frame 12 is
The inner and outer arms, which are U-shaped and have a vertically long rectangular column shape,
The piezoelectric element 11 is located substantially parallel to the expansion / contraction direction. One end (the lower end in FIG. 2) of the piezoelectric element 11 is supported on the lower end 14 of the frame 12 via a temperature compensating material 15. The piezoelectric element 11 and the temperature compensation material 15 are fixed to each other with an adhesive or the like. The piezoelectric element 11 is composed of laminated piezoelectric ceramics, and expands and contracts in the stacking direction (longitudinal direction) when a voltage is applied. To the other end surface of the piezoelectric element 11, a mover 17 supported by a four-bar linkage 16 so as to be movable only in the expansion / contraction direction of the piezoelectric element is fixed by an adhesive material or the like. One side of the mover 17 faces the one side upper portion of the frame 12 with a predetermined gap. On the opposing surfaces of the frame 12 and the mover 17, spring mounting surfaces for fixing the pair of first and second leaf springs 21 and 22 are formed parallel to the expansion and contraction direction of the piezoelectric element 11. ..

The spring mounting surface of the frame 12 has a first
The leaf spring 21 is fixed by brazing or the like in a state where it comes into contact with the one side plate surface. The second leaf spring 22 is fixed to the spring mounting surface of the mover 17 by brazing or the like in a state where the second leaf spring 22 is in surface-contact with the one side plate surface. The first and second leaf springs 21 and 22 are integrated at their upper portions, and the integrated portion is inserted into a groove formed in the tilting member 23 and fixed by brazing.
The base end of the printing wire 6 is fixed to the tip of the tilting member 23 by brazing. Further, in the present embodiment, a back stopper 24 made of low-repulsion rubber is provided at one end of the inner arm portion of the frame 12 for abutting and supporting one side of the tilting member 23 when the tilting member 23 is returned by tilting. There is. The temperature compensating material 15 adhered to the lower end surface of the piezoelectric element 11 corrects the contraction of the piezoelectric element 11 due to a change in ambient temperature by stretching, and the piezoelectric element 11 is supported from the supporting surface of the lower end portion 14 of the frame 12. The height up to one end is kept constant.

Lead wires 31, 32 led out by connecting one ends to both electrodes of the piezoelectric element 11 of each printing unit 2.
Are supported by a relay holder 33 made of an electrically insulating material, and are connected to the terminal wires 35 and 36 at the holder 33, respectively. The terminal wires 35 and 36 are the cover 5 and a spacer 37 made of an electrically insulating material and arranged on the outer surface of the cover 5.
And the other ends of the terminal wires 35 and 36 are connected to the spacer 37.
Is connected by soldering to a predetermined power supply line 39 which is disposed and supported on a wiring board 38 made of an electrically insulating material disposed on the outer surface of the. A signal based on print data is sent from the control circuit to the power supply line 39 of the wiring board 38.

This embodiment is configured as described above, and when a signal based on print data is output from the control circuit to each printing unit 2 and a voltage is applied between both electrodes of the piezoelectric element 11, the piezoelectric element 11 is printed. Is the stacking direction, that is, 1,
In FIG. 2, it extends in the direction of the arrow X by a predetermined length, and the mover 17 is moved accordingly. Then, the mover 16
The second leaf spring 22 is elastically deformed into a curved shape between the movable element 17 and the tilting member 23 in response to the moving force. Second
Due to the curved elastic deformation of the leaf spring 22, a rotational moment is generated in the direction of arrow P in FIG.
The leaf spring 21 is slightly elastically deformed, and the tip of the tilting member 23 is advanced to the printing position while being guided by the predetermined number of guide plates 7. In this way, the tilting member 23 is tilted by the elastic deformation of the second leaf spring 22 in a curved shape, whereby the piezoelectric element 11 is moved.
Is greatly expanded and transmitted to the print wire 6.
When the voltage application to the piezoelectric element 11 is cut off, the piezoelectric element 11 is shortened to its original state. Then, the mover 17,
The first and second leaf springs 21 and 22 and the tilting member 23 are returned to their original states, and the print wire 6 is returned and returned.

3 and 4 show the structure of the holder 33 used in the piezoelectric element drive type print head. The holder 33 is for relaying the lead wires 31 and 32, and includes a claw portion 33a held by the lower end portion 14 of the frame 12 by a spring force and a support portion 33b that supports the terminal wires 35 and 36. The claw portion 33a of each holder 33 has a hook-shaped tip, and the hook-shaped portion fits into the recess 14a of the lower end 14 of the frame 12 and is held by the spring force. The distance a from the base of the claw portion 33a to the lower portion of the hook portion is sufficiently larger than the distance b from the rear end of the frame 12 to the step of the recess 14a. The difference ab is set to about 100 μm if the amplitude at the position of the frame 12 is 20 μm, for example.
Therefore, in the present embodiment, the dimensions of these members are set so that ab is about 200 μm by taking into account the tolerances. Further, the distance between the claw portions is set to be larger than the thickness of the frame 12 so as not to prevent the holder 33 from sliding on the frame 12 in the longitudinal direction of the piezoelectric element 11.

The support portion 33b of the holder 33 is in the shape of a quadrangular prism, and the terminal wires 35,
It has two through holes for guiding and supporting 36 toward wiring board 38. The terminal wires 35 and 36 are inserted into the through holes of the supporting portion 33 a of the holder 33, and the lead wires 31 and 32 led out from both electrodes of each piezoelectric element 11 are inserted into one ends of the through holes.
Are connected by soldering. Lead wires 31, 32
Is connected to the terminal lines 35 and 36 with a slack, so that the vibration of the piezoelectric element 11 is not transmitted to the terminal lines 35 and 36. The other ends of the terminal wires 35 and 36 are connected to the spacer 3
After passing through the through hole formed in 7, the through hole formed in the wiring board 38 is connected to a predetermined power supply line 39 by soldering. The terminal wires 35 and 36 are the lead wires 31 and 3.
Since it is made of a metal wire having rigidity higher than that of 2, it is easy to pass through a predetermined through hole formed in the spacer 37 and the wiring board 38.

In the above structure, when the piezoelectric element 11 is driven at a predetermined driving frequency (for example, 4 kHz), its vibration is transmitted to the temperature compensating member 15 and the lower end portion 14 of the frame 12 and the claw portion of the holder 33. Reach 33a. However, the claw portion 33a of the holder 33 merely holds the holder 33 so as not to separate from the printing unit 2, and has a sufficient gap as compared with the amplitude of the piezoelectric element. Therefore, the above-mentioned vibration is not transmitted to the wiring board 38, so that the generation of noise can be avoided, and since the power supply lines 35 and 36 do not vibrate, the disconnection of the circuit can be avoided. Therefore, in the expansion / contraction direction of the piezoelectric element 11,
Can move relatively freely. Thus, the vibration of the piezoelectric element 11 at the lower end portion 14 of the frame 12 in the expansion / contraction direction is caused by the holder 33.
It hardly reaches the claw portion 33a.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, FIG. 5 is a perspective view showing another embodiment of the holder arranged in the print head. In this embodiment, the holder 40 is provided with the protrusion 40a, which is the cutout portion 1 of the lower end portion 14 of the frame.
4b is press-fitted in the Y direction. By loosely connecting the holder 40 and the lower end portion 14 of the frame,
The holder 40 can move relatively freely in the expansion and contraction direction of the piezoelectric element 11, and the same effect as described above can be obtained. Also in this embodiment, the difference between the diameter of the engaging portion of the protrusion and the diameter of the engaged portion of the notch is made sufficiently large with respect to the amplitude of the frame.

[0015]

As is apparent from the above description, according to the present invention, a holder for relaying the lead wire led out from each piezoelectric element is provided, and this holder is movably attached to a part of each piezoelectric element. Therefore, it is difficult for the vibration generated by the piezoelectric element to be transmitted to the holder and the wiring board.
It is possible to reduce the vibration that travels through each holder and reaches the wiring board, and it is possible to prevent the lead wires from being cut or the circuit connection of the power supply line on the wiring board to be broken at the soldered parts of each holder. It can be prevented. Also in this embodiment, the diameter of the engaging portion of the protrusion and the cut

[Brief description of drawings]

FIG. 1 is a side sectional view of a print head according to an embodiment of the present invention.

FIG. 2 is a side view of a print unit arranged in the print head of this embodiment.

FIG. 3 is a perspective view showing a holder arranged in the print head of this embodiment.

FIG. 4 is a cross-sectional view of a joint portion between the holder and the frame.

FIG. 5 is a perspective view showing another embodiment of the holder arranged in the print head.

[Explanation of symbols]

 1 Print Head Main Body 2 Printing Unit 4 Unit Holding Member 11 Piezoelectric Element 12 Frame 31, 32 Lead Wire 33 Holder 38 Wiring Board 39 Feed Line

Claims (1)

[Claims] 1. In a print head using a plurality of columnar piezoelectric elements that expand and contract in the longitudinal direction when a voltage is applied, a frame that supports each piezoelectric element and the expansion and contraction of the piezoelectric elements are printed on a print medium. A motion transmission mechanism for transmitting to the print wire, a unit holding member for arranging and supporting the frame supporting each of the piezoelectric elements, a holder for relaying the lead wire derived from each of the piezoelectric elements, and the lead wire. A piezoelectric element drive type print head, comprising: a wiring board that is electrically connected and supports a power supply line that supplies power from the outside, and a mounting position of the holder is movably mounted with respect to a mounting position of the frame.