JPH04363257A - Dot impact printing head device - Google Patents

Abstract

PURPOSE:To reduce the effect produced by the attachment of a reinforcing connecting body intended to prevent the occurrence of distortion in the rear end part of a support frame for supporting a piezoelectric element adapted to strike printing wire for printing resulting from the reactive action of the piezoelectric element taking place upon its driving. CONSTITUTION:A nearly circular reinforcing connecting body 32 is provided extending across a connecting part 15c and the rear face of an support part 15b in the supporting frames 15 arranged in a radial manner and the connecting part 15c, the rear face of the auxiliary support part 15b and the reinforcing connecting body 32 are attached together with an adhesive agent or joined together by electron beam welding.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a so-called dot impact print head that expands and contracts a piezoelectric element by applying a voltage and transmits the expansion and contraction movement to a printing wire that prints toward a printing medium such as paper. It concerns the structure of the device.

0002

[Prior Art] The present applicant previously published Japanese Patent Application Laid-Open No. 63-3128
No. 52 discloses a method for supporting the rear end of a piezoelectric element that expands and contracts when a voltage is applied, and disposing it on the front side of the piezoelectric element to transmit the expansion and contraction of the piezoelectric element to a printing wire that makes dots on a printing medium. The print unit consists of a support frame arranged on the longitudinal side of the piezoelectric element so as to support the motion transmission mechanism of the piezoelectric element. The head body is arranged radially on the back surface of the head body in a plan view so as to protrude and retract from the nose portion of the head body toward the front end. Proposed.

That is, in the case where the front end of the support frame in each printing unit is fastened to a first substrate such as a head main body, and the rear end of each support frame is fastened to a second substrate, It has been proposed that the support frame be fastened to at least one of the first and second substrates using bolts in a direction that intersects the direction of expansion and contraction of the piezoelectric element, such as in a direction substantially perpendicular to the direction of expansion and contraction of the piezoelectric element.

0004

However, in order to reduce the weight of the print head and make the shape of the print head more compact, there is a problem in that it is not possible to increase the rigidity of the support frame. In,
If bolts are tightened to the first and second substrates in substantially parallel to the expansion and contraction direction of the piezoelectric element, manufacturing errors of the support frame (particularly longitudinal dimensional errors along the expansion and contraction direction of the piezoelectric element) and support frame Because there is a manufacturing error in the flatness of the end surfaces of the first and second substrates that contact the front and rear end surfaces, the support frame may be compressed, for example, at a portion of the support frame where the front and rear lengths are large, due to the bolt tightening action. , the support frame is extended at a portion of the support frame where the front and rear lengths are short, resulting in unnecessary deformation of the support frame when assembling the print head. Also,
There was a problem in that the mounting position of each support frame was likely to vary in the direction of expansion and contraction of the piezoelectric element, so in order to solve this problem, in the prior art, the fastening direction was set in a direction that intersected the direction of expansion and contraction of the piezoelectric element. It was.

However, even if the tightening direction is changed as described above, it is not possible to absorb variations in the tightening force during bolt tightening work and manufacturing errors in the mounting position and support frame. Problems such as unnecessary deformation of the piezoelectric element, vibration of the support frame due to the expansion and contraction movement of the piezoelectric element during printing operations, and insufficient impact force could not be solved.

[0006]Furthermore, the bolts must be tightened at at least two locations, front and rear, for each support frame, and there is a problem in that the efficiency of the print head assembly work cannot be improved. The present invention aims to solve these technical problems all at once.

[0007]

Means for Solving the Problems In order to achieve the above object, the present invention provides a piezoelectric element that expands and contracts when a voltage is applied, and a movement that transmits the expansion and contraction of the piezoelectric element to a printing wire that prints on a printing medium. A plurality of printing units each including a transmission mechanism and a support frame that supports the piezoelectric element and the motion transmission mechanism are arranged on the back side of the head body so that the front end of each printing wire protrudes forward from the head body. In the dot impact print head device, the front part of the support frame of the plurality of printing units is fixed to the back side of the head main body, and the rear end part of each support frame is straddled over the rear end part of each support frame. Therefore, it is fixed by adhesive or welding to the reinforcing connector provided therein.

[0008]

[Operations and Effects of the Invention] In this way, by bonding the rear ends of the support frames of a plurality of printing units to the reinforcing connector disposed straddling them, the plurality of support frames can be attached to the reinforcing connector. It becomes an integral structure through
Further, since these front ends are fixed to the head body side, the rigidity of the head body is utilized at this point as well, so that the front ends are integrated, and the rigidity as a whole is significantly improved.

[0009] Therefore, when the piezoelectric elements in several locations of a large number of printing units are driven and the support frame at that location attempts to extend in a direction away from the back side of the head body due to reaction force, the piezoelectric elements are The rigidity of the supporting frame of the adjacent non-driven area is used to support the area, making it much more difficult to deform than when a single supporting frame supports the driving reaction force of the piezoelectric element at that area. This eliminates the need for insufficient impact force of the printing wire during driving.

[0010] Furthermore, when the rear end portions of a plurality of support frames and the reinforcing connector are fixed and connected by adhesive, even if there is a dimensional error in the longitudinal direction of the support frames, the rear end portions of the support frames and By automatically adjusting the thickness of the adhesive layer between the adhesive surface of the reinforcing connector and the adhesive surface, there is no undue stress on the support frame during the print head assembly process, which prevents the support frame from wobbling. It also absorbs manufacturing errors in the mounting position and support frame, and prevents unnecessary deformation of the support frame when assembling the print head, and vibration of the support frame due to the expansion and contraction movement of the piezoelectric element during printing operations. It can also solve the problem of lack of impact.

Furthermore, since a plurality of support frames and reinforcing connectors are connected together with adhesive, the efficiency of print head assembly work is greatly improved. In addition, when the rear end portions of the plurality of support frames and the reinforcing connector are fixed and connected by welding with little heat influence such as electron beam welding or laser welding, the strength of the joint is large and the heat supply is Since the amount of heat diffused locally and around the joint is small, even if there are heat-sensitive synthetic resin parts such as support frames near the joint, those parts will not be damaged by heat. The effect is that it can be done as follows.

0012

[Example] Next, an example will be described. Reference numeral 1 is a platen in a printer, and a push tractor 2 on the upstream side of paper feed is synchronized with the platen 1, or a pull tractor 3 on the downstream side of paper feed is synchronized with the platen 1. The dot impact print head device 4 is arranged so that its nose portion 12 faces the circumferential surface of the platen 1, and is driven by a carriage motor (not shown) such as a step motor to move the print head to the platen. The dot impact print head device 4 is mounted on a carriage 5 that reciprocates along the longitudinal direction of the paper.

FIGS. 2 to 4 show a first embodiment of the dot impact print head device 4, in which reference numeral 6 denotes a head main body which is approximately disk-shaped when viewed from the front, and reference numeral 7 is a reinforcing connecting body, which will be described later. A cylindrical portion 8 that integrally extends from the outer peripheral edge of the shaped reinforcing connector 7 toward the back side of the head main body 6 serves also as a cover. The head main body 6 and the reinforcing connector 7 are made of aluminum alloy.

Reference numeral 9 denotes a printing unit, in which a plurality of printing units 9 (24 in this embodiment) are arranged radially on the back side of the head main body 6, and the printing in each printing unit 9 is arranged on the front surface of the head main body 6. A hollow nose portion 12 in which a predetermined number of guide plates 11 for guiding the movement of the wire 10 are installed.
is installed protrudingly. As can be understood from FIG.
When the carriage moves in the left-right direction in FIG. 3, the positions of the tips of the book printing wires 10 protruding from the nose part 12 are arranged in a horizontally long rhombus (diamond shape) in the direction of movement. The printing wires arranged in the right half are arranged in a state shifted vertically by a half pitch with respect to the arrangement pitch of the arranged printing wires 10 in the vertical direction (paper feeding direction). This allows stamps to be made at fine pitches in the paper feeding direction. According to this configuration, the printing wires are arranged at different positions in the vertical direction along the carriage movement direction, so that the vertical straight character line "1"
When printing characters such as, all printing wires are not driven at the same time.

The printing unit 9 includes a longitudinal longitudinal piezoelectric element 13 formed by bonding piezoelectric ceramics in a laminated manner, and is attached to the front end of the piezoelectric element 13 to magnify the expansion and contraction movement of the piezoelectric element and transmit it to the printing wire 10. a motion transmission mechanism 14 for
A support frame 1 extends rearward from the back surface of the head body 6 to support the motion transmission mechanism 14 and the piezoelectric element 13.
5, and the support frame 15 is integrally formed in a U-shape by a main support portion 15a, a sub-support support portion 15b, and a connecting portion 15c so as to surround both longitudinal sides and the rear end of the piezoelectric element 13. ing. Note that the auxiliary support portion 15b may be fixed to the connecting portion 15c by brazing, welding, or the like.

When a voltage is applied, the piezoelectric element 13 expands and contracts in its lamination direction (longitudinal direction), and the temperature compensator 1 corrects the size of the piezoelectric element 13 that shrinks due to temperature rise.
6 connects the connecting portion 15c of the support frame 15 and the piezoelectric element 13
and the rear end of the base plate with adhesive. Reference numeral 17 denotes a wire support arm having a substantially triangular shape in side view and having the base end of the printing wire 10 brazed to its tip;
At the base of the main column 15a, 21 distal end connecting portions of a parallel first leaf spring 19 and a second leaf spring 20 extending rearward in the longitudinal direction are fitted and fixed. The base end portion of the second leaf spring 20 is brazed and fixed to the side surface of the main support column 15a, and the base end portion of the second leaf spring 20 is also brazed to the side surface of the mover 22, which is fixed to the front end surface of the piezoelectric element 13 by brazing or the like. It will be fixed by attaching it etc.

As shown in FIG. 5, when the piezoelectric element 13 and the movable element 22 extend in the direction of the arrow P by applying a voltage, the connecting end portions 21 of the leaf springs 19 and 20 are rotated in the direction of the arrow X. Then, the amount of displacement is magnified by the wire support arm 17, and the printing wire 10 is driven to protrude from the nose portion 12 and print on the paper on the surface of the platen 1 via the ink ribbon.

When the voltage application is released, the wire support arm 17 rotates in the opposite direction due to the elastic force of both leaf springs 19 and 20, and the arm-side stopper 18a made of resin comes into contact with the support-side stopper 18b. It touches and stops. Figures 5 and 6
Reference numeral 23 denotes a four-bar link mechanism member disposed across the other side of the movable element 22 and the sub-supporting column 15b, and the four-bar link mechanism member 23 is made of an elastic material such as a spring plate. Becomes,
The wide side plate parts 23a, 23a are provided with a notch hole 24 which is approximately H-shaped in side view, and the left and right wide side plate parts 23a, 23a are connected to the sub-support part 15b on the outer diameter side of the notch hole 24. Both left and right wide side plates 2 of the four-bar linkage mechanism member 23 are fixed to the front and back sides and the front and back sides of the movable element 22 by brazing, welding, etc., respectively, and when the piezoelectric element 13 expands and contracts by applying voltage,
3a and 23a are elastically deformed into a parallelogram shape when viewed from the side, so that the movable member 22 can move in parallel along the longitudinal direction of the sub-pillar part 15b whose position is fixed.
(See the two-dot chain line in the figure).

In this way, the mover 22 is attached to the sub-support part 15b.
In other words, the piezoelectric element 13
If the piezoelectric ceramic is configured to move linearly in the longitudinal direction, no bending force will be applied to the laminated adhesive surface of the piezoelectric ceramic, and the laminated portion or the adhesive surface will not be inadvertently peeled off. The support frame 15 in each printing unit 9 has its main support portion 1
At the front end surface of 5a, it is fixed by screws 27 to the back surface of an annular mounting piece 26 which is fixed to the back surface of the head body 6 via a rubber spacer 50 (in the embodiment shown in FIG. There is. In this embodiment, the bolts are tightened from the side surface of the cylindrical part of the head body, but the rubber spacer 50
It is also possible to pass through and tighten the bolts from the front.

[0020] Each printing unit 9 support frame 1
The inner surface of the substantially disk-shaped reinforcing coupling body 7 is faced so as to straddle the back surface of the coupling part 15c and/or the sub-support part 15b in 5, and the inner surface of the reinforcing coupling body 7 and each of the coupling parts 15c and/or The back surface of the sub-support column 15b is bonded and fixed by an adhesive such as a thermosetting resin such as epoxy resin, or by brazing. The guide grooves 28 as shown in FIG.
This eliminates misalignment of the connecting portion 15c and/or the sub-support portion 15b, and contributes to increasing the bonding area.

[0021] The inner surface of the reinforcing connector 7 and each of the connectors 1
5c and/or the back surface of the sub-pillar part 15b are fixed and connected by welding with little heat influence such as electron beam welding or laser welding, the strength of the joint is large, and the heat supply is localized. Because the amount of heat diffusion around the joint is small,
Even if heat-sensitive synthetic resin parts such as the support frame are present in the vicinity of the joint, these parts can be prevented from being damaged by heat.

Note that a ring made of rubber or the like is installed between the annular front edge of the cylindrical portion 8 extending integrally from the outer peripheral edge of the reinforcing connector 7 and the annular rear edge 6a on the back side of the head body 6. A seal body 29 having a shape is inserted. In the embodiments shown in FIGS. 7 and 8, the reinforcing connecting body 30, which is substantially annular in plan view, is made to straddle the back surface (rear surface) of the connecting portion 15c and/or sub-support portion 15b of the support frame 15 in all printing units, The reinforcing connecting body 30 and each of the connecting portions 15c and/or the auxiliary support portions 15b are fixed by adhesive, brazing, electron beam welding, laser (micro) welding, or the like. A reinforcing connecting body 30 and a separate cover body 31 are attached to the head main body 6, and the rest of the structure is substantially the same as that of the first embodiment.

In the embodiments shown in FIGS. 9 and 10, the reinforcing connecting body 32, which is approximately annular in plan view, is connected to the connecting portion 15c and/or the sub-support portion 15b of the support frame 15 in all printing units.
The reinforcing connecting body 32 and each of the connecting parts 15c and/or the sub-pillar parts 15b are fixed by adhesive, brazing, electron beam welding, laser (micro) welding, etc. so as to straddle the back surface (rear surface) of and fix it. Then, the reinforcing connector 32
A cover body 33, which is separate from the head body 6, is fixed to the side surface of the head body 6 with screws or the like.

Reference numeral 34 indicates a terminal for energizing the piezoelectric element 13 in each printing unit 9, and a lead wire 35 of each terminal 34 is exposed to the outside through a mounting hole 36 formed in the bottom plate 33a of the cover body 33. After that, each mounting hole 36 is filled with a sealing material 37 such as synthetic resin. Further, on the outer surface of the bottom plate 33a of the cover body 33, a regulating plate 38 made of electrically insulating synthetic resin is attached with a conical guide hole for easily guiding the lead wire 35 of the terminal 34, which is easily bent and misaligned. After that, a printed circuit board 39 is attached thereto. Furthermore, the main support portion 15 in the support frame 15 of each printing unit 9
After fixing the front end of a to the annular mounting body 40 with screws 41 and nuts 42 and positioning and assembling, the mounting body 4
0 is fixed to the head body 6 with screws 43.

According to these configurations, the rear ends of the support frames 15 in the plurality of printing units 9 are bonded to the reinforcing connectors 7, 30, 32 disposed straddling these, or by electron beam welding. By welding and fixing, the plurality of support frames 15 become an integral structure via the reinforcing connectors 7 and 30, and the rigidity as a whole is significantly improved. Therefore, for example, the tip of the printing wire 10 drives the piezoelectric elements 13 at several locations among the 24 printing units 9 arranged in a diamond shape as described above, and the support frame 15 at that location is moved by the reaction force. When trying to extend away from the back side of the head body 6, the support frame 15 of the adjacent non-driving part (the front end of which is directly fixed to the head body 6) is , or fixed to the mounting pieces 26 and 40 and then fixed to the head body), compared to supporting the drive reaction force of the piezoelectric element at that location with one support frame. , it becomes much more difficult to deform (expand and contract), and as a result, the impact force of the printing wire during printing driving is no longer insufficient.

Moreover, when the rear end portions of a plurality of support frames and the reinforcing connector are fixed and connected by adhesive, even if there is a dimensional error in the longitudinal direction of the support frames, the rear end portions of the support frames due to these discrepancies will be removed. automatic adjustment of the thickness of the adhesive layer between the adhesive surface of the reinforcing connector and the adhesive surface of the reinforcing connector (excess adhesive is removed where the connecting part 15c and/or the secondary column part 15b of the support frame protrudes most rearward) By protruding,
The gaps between the respective connecting portions 15c and/or sub-pillar portions 15b and the bonding surfaces of the reinforcing connectors 7, 30, and 32 are filled with just the right amount of adhesive. Since no unreasonable stress is generated on the support frame, it is possible to absorb looseness of the support frame and manufacturing errors in the mounting position and support frame, etc., and to prevent unnecessary deformation of the support frame when assembling the print head and prevent printing. It is also possible to solve the problem of vibration of the support frame and lack of impact force caused by the expansion and contraction movement of the piezoelectric element during work.

Furthermore, since a plurality of support frames and reinforcing connectors are connected all at once using adhesive, the efficiency of print head assembly work is greatly improved. In addition, welding methods such as electron beam welding and laser welding that can locally increase the heat addition density and require a small amount of heat input cause less thermal distortion to members such as the support frame, and can also improve bonding strength. It can be made larger than by using agents. In the case of welding, it goes without saying that the connecting portion 15c and/or the auxiliary support portion 15b of the support frame 15 and the reinforcing connecting bodies 7, 30, and 32 must be made of metal. As shown in FIGS. 9 and 11, the connecting portion 15 of the support frame 15
By providing electron beam welding points 52 on both the rear surfaces of the sub-post part 15b and the sub-post part 15b, it is possible to further prevent deformation of the parts of the sub-post part 15b which have relatively low rigidity or are easily deformed.

Note that if the gaps between the radially arranged printing units 9 are filled with a filler material having good thermal conductivity such as silicone rubber, the heat generated by driving the piezoelectric elements 13 will be transferred through the filler material. It can be quickly transmitted to the metal support frame 15, the head main body 6, the reinforcing connectors 7, 30, 32, the cylindrical part 8, etc., and then released to the outside. At this time, noise can be reduced by providing a gap between the cover body and the head body and filling this gap with the filler material. In this case, if heat dissipation fins 32 are provided on the outer periphery of the cylindrical portion 8 as shown in FIGS. 2 and 3, the heat dissipation effect will be further improved. Further, as a method of fixing the cover body 31 and the head body 6, it is possible to fix them with a double-sided adhesive tape with rubber or the like sandwiched therebetween, or to fit them together with a ring-shaped shield material 51 sandwiched therebetween as shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a printer.

FIG. 2 is a side sectional view of a first embodiment of a print head.

FIG. 3 is a front view of the print head.

FIG. 4 is a view taken along the line IV-IV in FIG. 2;

FIG. 5 is an enlarged side view of main parts.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

FIG. 7 is a side sectional view of the second embodiment.

FIG. 8 is a view taken along arrows VIII-VIII in FIG. 7;

FIG. 9 is a side sectional view of the third embodiment.

10 is a perspective view of the mounting body 41. FIG.

11 is a partially cutaway view taken along the line XI-XI in FIG. 9; FIG.

FIG. 12 is a sectional view of a main part of another embodiment.

[Explanation of symbols]

1 Platen 4 Dot impact print head device 6
Head main body 7, 30, 32 Reinforcement connection body 9
Printing unit 10 Printing wire 13 Piezoelectric element 14 Motion transmission mechanism 15 Support frame 15a Main support section 15b Sub-support section 15c Connection section 17 Wire support arm 19 First leaf spring 20 Second leaf spring 21 Tip connecting section 22 Mover 23 4 Knot link mechanism members 31, 33 Cover body 52 Electron beam welding location

Claims (1)

[Claims] 1. A piezoelectric element that expands and contracts when a voltage is applied, a motion transmission mechanism that transmits the expansion and contraction of the piezoelectric element to a printing wire that prints on a print medium, and a motion transmission mechanism that supports the piezoelectric element and the motion transmission mechanism. A dot impact print head device comprising a plurality of printing units comprising a support frame arranged on the back side of the head main body such that the front end of each printing wire protrudes and retracts forward from the head main body, wherein the plurality of printing units The front part of the support frame is fixed to the back side of the head main body, while the rear end part of each support frame is glued or welded to a reinforcing connector disposed straddling the rear end of each support frame. A dot impact print head device characterized by being fixed in place.