JPH0528643U - Wire printing head device - Google Patents

Abstract

(57) [Summary] [Objective] The link plate 23 constituting the link mechanism for moving the mover 14 in the same direction as the expansion and contraction direction of the piezoelectric element 5 in the print head device is easily handled and the link plate 23 is easily handled. Reduce the heat effect during welding. [Structure] Struts 6 arranged along the sides of the piezoelectric element 5
b and the mover 14 attached to the front end of the piezoelectric element 5 are connected by the link plate 23. The projecting portions 35 and 36 are integrally formed in the substantially H-shaped window hole 24 for forming the link mechanism in the link plate 23 so as to reduce the opening area of the window hole 24.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure of a wire print head device in which a print wire is printed by a piezoelectric element that expands and contracts when a voltage is applied.

[0002]

[Prior Art]

 A print head device using a piezoelectric element as a drive means for a print wire has the following configuration, as shown in, for example, Japanese Patent Laid-Open No. 130153/1990. That is, the piezoelectric element is formed by stacking piezoelectric ceramics, and is configured to extend in a direction perpendicular to the stack surface by energizing and charging the piezoelectric element, and extending along the side of the piezoelectric element. The rear end of the piezoelectric element is supported by the rear end of the support frame. The base end of a first spring plate extending along the extension direction of the piezoelectric element is fixed to the front end of the support frame, and the front end of the first spring plate is attached to the base end of the arm to which the print wire is attached. To the base end of the second spring plate, which extends parallel to the first spring plate, and the base end of the second spring plate is fixed to the front end of the piezoelectric element. It is configured to be fixed to one side of the mover.

Then, the movement of the piezoelectric element that expands due to charging is transmitted to the arm via the mover and the second spring plate. Since the arm is connected by the first spring plate during this movement, both the first spring plate and the second spring plate are elastically curved, and the arm is pushed up in the direction in which the print wire advances. Rotate to. As a result of the reaction of the movement, a reaction force (bending moment) is generated in the mover and the piezoelectric element so that the mover and the piezoelectric element tend to be convex in the direction away from the support frame. Therefore, tensile stress is generated on the convex curved side, and it is said that the bonding surface between the piezoelectric element and the movable element and the laminated surface of the piezoelectric ceramic are peeled off by repeated driving of the piezoelectric element and the piezoelectric element is damaged. There was a problem.

In order to avoid this inconvenience, for example, in the prior art disclosed in Japanese Patent Application Laid-Open No. 2-30547 previously disclosed by the applicant of the present invention, the movable element and the support column in the supporting frame disposed on the side of the movable element are disclosed. It is proposed that the parts be connected to each other by a link plate serving as a four-bar link mechanism member, and that the mover be constrained so as to move substantially parallel to the expansion and contraction direction of the piezoelectric element.

[0005]

[Problems to be solved by the device]

 A substantially H-shaped window hole is formed in the link plate to form a four-bar link mechanism. However, in the past, the shape of this window was designed with priority given to its function, so when removing one by one from the state where the link plates after punching from the material plate material were accumulated in the collection location, etc. There is a problem that the link plates are entangled with each other because corners and the like are fitted into the window holes. Also, since the thermal effect such as spot welding when fixing the link plate to the side surface of the mover and the side surface of the support was not taken into consideration, heat was not applied to the corners of the approximately H-shaped window hole of the link plate. The strength was deteriorated due to the strain, and there was a problem such as lack of durability as a 4-link mechanism.

An object of the present invention is to solve the above problems and improve the reliability of the print head.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a piezoelectric element that expands and contracts when a voltage is applied, and a motion transmission mechanism that transmits the expansion and contraction of the piezoelectric element to a print wire for printing on a print medium via a mover. , A support frame that has a pillar portion arranged along the side of the piezoelectric element and that supports the rear end of the piezoelectric element, and a guide frame for moving and guiding the mover in a direction parallel to the expansion and contraction direction of the piezoelectric element. In a print head device including a link plate for configuring a link mechanism, a link plate that connects the mover and a supporting column of the support frame is formed of a spring plate material, and the link plate has a link mechanism. A substantially H-shaped window hole for forming the above is formed, and a convex portion for preventing the entanglement of other link plates is formed in the window hole.

[0008]

【Example】

 Next, an embodiment embodying the present invention will be described. As shown in FIG. 1, reference numeral 1 denotes a head body that is substantially disc-shaped in a front view, and a cover 2 is integrally formed from the outer peripheral edge of a substantially disc-shaped bottom plate portion 2a toward the back side of the head body 1. The head body 1 and the cover 2 are made of aluminum alloy.

Reference numeral 4 denotes a printing unit, and a plurality of (24 in the embodiment) printing units 4 are radially arranged on the back surface side of the head main body 1. On the front surface of the head main body 1, a hollow nose 1a in which a predetermined number of guide plates 3 for moving and guiding the printing wires 7 in each printing unit 4 are installed is projected. The printing unit 4 is mounted on the front end of the piezoelectric element 5 which is formed by adhering piezoelectric ceramics in a laminated form, and is attached to the front end of the piezoelectric element 5 so as to expand the expansion and contraction movement of the piezoelectric element and transmit it to the printing wire 7. 2 and a support frame 6 extending rearward from the back surface of the head body 1 for supporting the motion transmitting mechanism 9 and the piezoelectric element 5. The support frame 6 is integrally formed in a U-shape by a main strut portion 6a, a sub strut portion 6b, and a connecting portion 6c so as to surround both left and right sides and a rear end portion along the longitudinal direction of the piezoelectric element 5. . Note that the sub-column portion 6b may be fixed to the connecting portion 6c by brazing or welding.

When a voltage is applied, the piezoelectric element 5 expands and contracts in the stacking direction (longitudinal direction), and the piezoelectric element 5 shrinks due to a temperature rise, so that it has a positive temperature expansion characteristic for correcting it. The temperature compensator 43 is inserted between the connecting portion 6c of the support frame 6 and the rear end of the piezoelectric element 5 and fixed by an adhesive. The motion transmitting mechanism 9 converts the expansion and contraction of the piezoelectric element 5 into the rotational motion of the arm 8 so that the amount of advance / retreat of the printing wire 7 attached to the tip of the arm 8 is enlarged. The motion transmission mechanism 9 for this purpose uses an Eden spring composed of two parallel plate-shaped drive spring bodies. That is, the drive spring body is formed by integrally connecting one ends of the first leaf spring body 12 and the second leaf spring body 13 to the joint portion 10 made of a rigid body, and connecting the so-called Π shape in a front view. is there. The base end of the first leaf spring body 12 is brazed and fixed to one side surface of the main support portion 6a, while the base end of the second leaf spring body 13 is also brazed to the mover 14 provided at the front end of the piezoelectric element 5. It sticks. The extending direction of the first leaf spring body 12 and the second leaf spring body 13 is set to be parallel to the extending direction of the printing wire 7 and opposite to the extending direction.

The lower surface of the movable element 14 and the front surface of the piezoelectric element 5 may be bonded and fixed with an adhesive, or the movable element 14 is brought into contact with the front surface of the piezoelectric element 5 in a contracted state while being pressed. It may be configured as follows. In addition, one or a plurality of spacers may be interposed between the mover 14 and the piezoelectric element 5, and in that case, the spacer on the mover 14 side and the spacer on the piezoelectric element 5 side are pressed and contacted. It may be in a state or may be fixed to each other with an adhesive.

As shown in FIG. 3, when the piezoelectric element 5 and the mover 14 move in the arrow y direction by the application of a voltage, the connecting portion 10 at the tip of the both leaf spring bodies 12, 13 rotates in the arrow A direction. It is displaced (see the chain double-dashed line in FIG. 3). The displacement amount is enlarged by the arm 8, and the printing wire 7 is driven so as to project from the nose portion 1a and print on the paper 41 on the platen 40 via the ink ribbon 42. When the piezoelectric element 5 is discharged, the piezoelectric element 5 contracts in the direction of the arrow y ', so that the tip end side of the arm 8 is restored to the platen 40 by the restoring force of the elastic deformation of the two plate members 12 and 13. Retreat from the surface.

A stopper 15 made of resin or the like attached to the arm 8 comes into contact with a support-side stopper 16 attached to the sub strut portion 6b, and the arm 8 is damped and stopped while repeating vibration. Reference numerals 23 and 23 shown in FIGS. 2 to 6 are a pair of link plates as a four-bar linkage mechanism member arranged across the other side portion of the mover 14 and the sub strut portion 6b. The link plate 23 is made of an elastic material such as a spring plate. The link plate 23 has two vertical link portions 26, 27 parallel to the expansion / contraction direction of the piezoelectric element 5, and four hinge portions 28, 20, 30 elastically deformable between the two vertical link portions 26, 27. In order to form a so-called four-joint parallel link with a pair of lateral link portions 32 and 33 that are erected with a pair of lateral link portions 32 and 33, a cutout hole 24 having a substantially H shape in side view is formed in the wide side plate portion. .. On the outer diameter side of the cutout hole 24, the vertical link portions 26 and 27 are welded (resistance welding, spot welding) to the front and back side surfaces of the auxiliary column portion 6b and the fixed portions 25 on the front and back side surfaces of the mover 14, respectively. Fix by attaching. With this configuration, when the piezoelectric element 5 expands and contracts due to the application of a voltage, the link plate 23 elastically deforms into a parallelogram shape in a side view and moves parallel to the movable element 14 along the longitudinal direction of the position-fixed sub-column portion 6b. It is configured to be able to move. In other words, the mover 14 is configured to move linearly along the longitudinal direction of the piezoelectric element 5.

Therefore, the strength of the elastic force of the second leaf spring 13 biased and attached to one side surface of the mover 14 and the elastic force of the link plate 23 biased and attached to the other side surface of the mover 4. Even if there is a difference and a bending moment acts on the lower surface side of the mover 14, the mover 14 and the piezoelectric element 5 and the bonding surface (bonding surface along the x direction which is the direction perpendicular to the y direction) A large shearing force does not act on the adhesive in (4), and sliding friction between the spacer on the lower surface of the movable element 14 and the spacer on the front surface of the piezoelectric element 5 is also eliminated. Further, the adhesion between the laminated piezoelectric ceramics in the piezoelectric element 5 does not peel off.

The guide plate portions 34, 34 formed integrally or separately from the link plate 23 are spot welded to the main strut portion 6a and the sub strut portion 6b at 25 fixing portions similarly. The movable element 14 is movably guided between the inner sides of both the guide plate portions 34, 34 while being fixed. Reference numerals 35 and 36 are convex portions formed so as to integrally project into the window hole 24 of the link plate 23. Both the convex portions 35 and 36 face each other from the vertical link portions 26 and 27. The opening area of the window hole 24 is narrowed by protruding. As a result, when the link plates 23 punched out from the material plate are stored in the stacking box, the corners of the falling link plates 23 are obliquely above the wide surface of the link plates 23 below and inside the window hole 24. To prevent them from becoming entangled with each other (or reduce the probability of entanglement). In order to prevent this entanglement, in addition to the convex portions 35 and 36, a convex portion 37 as shown by a dashed line in FIG. 6 may be formed on the lateral link portion 32 and / or 33.

Further, the respective convex portions 35 and 36 which are continuously provided at the vertical link portions 26 and 27 are formed concentrically with the center of the electrode position of a round bar for spot welding (resistance welding) of the fixing portion 25. To do. With this configuration, the length from the center of the electrode position during the spot welding operation to the edge of the window hole 24 of the vertical link portions 26, 27 facing the side surface of the auxiliary column portion 6b or the mover 14 becomes longer, It is possible to reduce the generation of dust (metal powder) by reducing the scattering of metal sparks in the nugget during welding.

Further, due to the presence of the above-mentioned convex portions 35 and 36, the area of the vertical link portions 26 and 27 is increased by the area of the convex portions 35 and 36, and diffusion of heat generated by spot welding can be promoted. It is possible to reduce the influence of heat on the small hinge portions 28, 20, 30, 31 and prevent the fatigue limit and the like from being reduced when each hinge portion repeatedly undergoes predetermined elastic deformation. This is because the metal plate that has been subjected to the prescribed cold rolling and heat treatment is so-called tempered so as to have the prescribed tensile strength, mechanical strength such as elongation, etc. A so-called annealing phenomenon occurs in the hinge part, which lowers the fatigue limit and causes fatigue rupture under a load with a small repetitive stress.

Further, when the link plate 23 and the guide plate portion 34 are integrally formed as shown in FIG. 6, a convex portion 38 is formed at the opening end of the continuous gap 39 between the link plate 23 and the guide plate portion 34. And the gap dimension (H1) from the tip edge of the convex portion 38 is set to be smaller than the plate thickness dimension (t1) of the link plate 23, a portion of the link plate 23 or a guide portion different from the opening end. 34 becomes difficult to fit, and it is possible to prevent a plurality of link plates from being entangled with each other when stacking the above-mentioned link plates 23 and the like. Further, when the convex portion 38 is located at the position of the vertical link portion 27, generation of dust and reduction of thermal influence can be achieved as described above.

As shown in FIG. 7, according to the present invention, when the link plate 23 is formed separately from the guide plate portion 34, the convex portions 35 and 36 are formed in the window hole 24 as in the above-described embodiment. Can be formed. In this embodiment, since the link plates 23 on both the left and right sides are separately provided, there is an effect that a bending step is unnecessary as compared with the left and right integrated type shown in, for example, Japanese Patent Laid-Open No. 2-145345. is there.

[0020]

[Operation and effect of the device]

 As described above, according to the present invention, since the movable element and the supporting column are connected by the link plate, the movable element can be restrained so as to move in a direction parallel to the expansion and contraction direction of the piezoelectric element. It is possible to improve the durability and reliability of the print head by preventing damages such as. Then, since the space where the window hole for constructing the link mechanism is formed in the link plate is narrowed by the convex portion protruding in the window hole, the punched link plates are entangled with each other in an integrated state. The situation can be prevented. In addition, the presence of the above-mentioned convex portion has the effect of facilitating heat dissipation during welding of the link plate and preventing deterioration of the mechanical strength of the link mechanism.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a print head.

FIG. 2 is a perspective view of a printing unit.

FIG. 3 is a front view of a main part.

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

5 is a cross-sectional view taken along the line VV of FIG.

FIG. 6 is a front view of a link plate.

FIG. 7 is a front view of another embodiment of the link plate.

[Explanation of reference numerals] 1 head main body 3 guide plate 5 piezoelectric element 6 support frame 6a main strut portion 6b sub strut portion 6c connecting portion 7 printing wire 8 arm 9 motion transmission mechanism 12 first leaf spring body 13 second leaf spring body 14 Movable element 15 Arm side stopper 16 Support side stopper 23 Link plate 24 Window hole 25 Fixed part 26, 27 Vertical link part 28, 29, 30, 31 Hinge part 32, 33 Horizontal link part 34 Guide plate part 35, 36, 37, 38 convex

Claims (1)

[Scope of utility model registration request] 1. A piezoelectric element which expands and contracts when a voltage is applied,
A piezoelectric element having a motion transmitting mechanism for transmitting the expansion and contraction of the piezoelectric element to a print wire for printing on a print medium via a mover, and a column portion arranged along the side of the piezoelectric element A print head device comprising a support frame for supporting a rear end of the print head and a link plate for forming a link mechanism for moving and guiding the mover in a direction parallel to the expansion and contraction direction of the piezoelectric element, wherein the mover and the mover are provided. A link plate for connecting to the support column of the support frame is formed of a spring plate material, and a substantially H-shaped window hole for forming a link mechanism is formed in the link plate, and another window hole is formed in the window hole. A wire printing head device, characterized in that a protrusion is formed to prevent the link plate from becoming entangled.