JPH0796614A - Dot impact print head device - Google Patents

Abstract

PURPOSE:To improve printing performance by a method wherein the whole print head assembly is miniaturized and, at the same time, the strength of a printing head is increased. CONSTITUTION:The supporting frame 11 of a printing unit 3 is formed in a U-shape, between the main strut part 11a and the sub-strut part 11b of which a piezoelectric element 13 is supported. The printing units 3 are arranged radially so as to fix the main strut parts 11a to an annular member 6. A rigid reinforcing member 19 is inserted in a central space part 9 formed by the respective printing units 3. The reinforcing member 19 and the side face of the sub-strut part 11b are bondingly fixed together with an adhesive over wide bond area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot impact print head device in which a printing wire is printed by a piezoelectric element which expands and contracts when a voltage is applied.

[0002]

2. Description of the Related Art Conventionally, in a dot impact print head device of the type driven by a piezoelectric element, as shown in FIG. 7, a cylindrical nose portion 1 is provided at the center of the front surface of a head front cover 1.
a is formed to project. A plurality of guide plates 2 are arranged in the nose portion 1a to guide the movement of the printing wire 4 of the printing unit 3. On the other hand, a ring-shaped member 6 is provided on the outer peripheral portion of the rear surface of the front cover 1 via a rubber spacer 5.
Are fixed by screws (not shown). further,
A predetermined number of printing units 3 are radially fixed to the ring-shaped member 6 by screws (not shown). Then, in order to increase the strength of the printing unit, the frame rear end portion of each printing unit is fixed to one metal disk 8 (reinforcing member) by electron beam welding.

[0003]

However, in the conventional apparatus, since the rear end of the frame of the printing unit is fixed to the metal disk, the entire print head becomes large by the thickness of the metal disk. When the metal disk is made thin, the strength of the print head becomes weak, and there is a problem that the print unit vibrates in response to the print operation and the desired impact force cannot be obtained.

Further, since the rear end of the frame of the printing unit is electron beam welded to the metal disk, the printing unit is distorted by the heat generated during the welding, which causes a problem in driving the printing wire. In order to prevent the printing unit from being distorted, if the lower end of the frame of the printing unit is adhesively fixed to the metal disk with adhesive, the adhesive fixing has a weaker holding force than electron beam welding, and the lower end of the frame Since the adhesion area between the metal portion and the metal disk is small, the lower end of the frame cannot be fixed to the metal disk with a sufficient fixing and holding force.

The present invention has been made to solve the above-mentioned problems, and it is possible to reduce the size of the entire print head, increase the strength of the print head, and obtain a desired impact force. To provide.

Further, even when the reinforcing member is adhered and fixed with an adhesive, the reinforcing member can be fixed with a sufficient fixing and holding force, so that the deformation of the printing unit is prevented and the driving of the printing wire is hindered. An object of the present invention is to provide a dot impact print head device that does not cause trouble.

Another object of the present invention is to provide a dot impact print head device in which the size of each print unit itself can be reduced and the print head as a whole can be made smaller.

[0008]

SUMMARY OF THE INVENTION A dot impact print head device of the present invention includes a piezoelectric element that expands and contracts when a voltage is applied, and a motion transmission for transmitting the expansion and contraction of the piezoelectric element to a print wire that stamps a print medium. A plurality of printing units supporting the mechanism on a supporting frame extending in the longitudinal direction of the piezoelectric element, and a supporting member for radially arranging the plurality of printing units and fixing one longitudinal end of the supporting frame of the printing units. , A reinforcing member that is arranged in the central space of the printing units that are radially arranged and that has rigidity to fix the side surface along the longitudinal direction of the support frame of each printing unit.

In a preferred embodiment, the support frame includes a base portion that supports one end of the piezoelectric element, and a main strut portion and a sub strut portion that extend from the base portion along both sides of the piezoelectric element in the expansion and contraction direction thereof. Is formed in a substantially U shape, the main strut portion is fixed to the support member at one end opposite to the base portion, and the side surface along the longitudinal direction of the sub strut portion is fixed to the reinforcing member.

The reinforcing member is adhesively fixed to the supporting frame of each printing unit with an adhesive.

The cross-sectional shape of the reinforcing member is preferably such that the distance between the plurality of support frames and the reinforcing member is equal.

[0012]

With the above structure, the printing units are radially arranged, and the reinforcing member having rigidity is provided in the central space thereof.
It is fixedly arranged on the side surface of the support frame of each printing unit. The vibration of the printing unit due to the reaction of the printing operation is suppressed by the reinforcing member fixed to the side surface along the longitudinal direction of the support frame.

In a preferred embodiment, the reinforcing member can prevent the sub-column portion of the support frame from opening with respect to the main column portion as the piezoelectric element extends.
The member that connects the main strut portion and the sub strut portion for reinforcement is unnecessary, and the size of the support frame can be reduced.

Further, since the cross-sectional shape of the reinforcing member is such that the distance between the plurality of supporting frames and the reinforcing member is equal, it is injected between the reinforcing member and the supporting frame when the reinforcing member and the supporting frame are adhesively fixed. Since the amounts of adhesive applied are all equal, the forces exerted on the adhesive when cured and heated are applied equally to any printing unit, so that a stable and predetermined print wire operation is achieved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

The front cover 1 of the print head has a hollow cylindrical nose portion 1a protruding from the center of the front surface of a circular substrate portion. A plurality of guide plates 2 are arranged in the nose portion 1a to guide the movement of the printing wire 4 of the printing unit 3. On the other hand, a ring-shaped member 6 is fixed to the outer peripheral portion of the rear surface of the front cover 1 by a screw (not shown) via a spacer 5 made of rubber. Further, 24 printing units 3 are radially fixed to the ring-shaped member 6 by screws (not shown). A reinforcing member 19 described later is inserted and arranged in the central space portion 9 formed by the printing units 3 arranged in a radial pattern.

The printing unit 3 is shown in detail in FIG. The piezoelectric element 13 has a prismatic shape and extends in the longitudinal direction (arrow X) when a voltage is applied. The support frame 11 includes a base portion 11c that supports one end of the piezoelectric element 13, and a main strut portion 11a and a sub strut portion 11b that extend from the base portion along both sides of the piezoelectric element in the expansion and contraction direction, respectively, and are substantially U-shaped.
It is formed in a letter shape. A terminal 12 is connected to one end (lower end in the figure) of the piezoelectric element 13 via a lead wire 10. A movable element 14 is fixed to the other end (upper end in the figure) of the piezoelectric element 13, and a leaf spring 15 is fixed to the side surface of the movable element 14. A leaf spring 16 is fixed to the upper end side surface of the main strut portion 11a facing the leaf spring 15.
Both leaf springs 16 and 15 are integrally connected to each other by a connecting portion 17 at their free ends. One end of an arm 18 is fixed to the connecting portion 17, and the print wire 4 is fixed to the other end of the arm 18.

In addition, the upper end portion 2 of the auxiliary strut portion 11b in FIG.
A four-bar linkage member 21 is fixed to 0. The four-joint link mechanism member 21 is formed of an elastic material such as a spring plate, and its vertical side portions 21a and 21b are fixed to the sub-column portion 11b and the mover 14, respectively, and the upper and lower ends of both vertical side portions are elastic. It is connected by a deformable lateral side portion 21c. Main support part 1
The connecting member 22 connects the 1a and the sub-column portion 11b. On the other hand, the arm 18 is provided with a stopper 18a that comes into contact with the upper end portion 20.

The printing unit 3 is fixed by a screw (not shown) with the upper end of the main column 11a in the figure being brought into contact with the rear surface of the ring-shaped member 6. Motion transmission mechanism (leaf springs 15, 1
6, the arm 18) and the print wire 4 are arranged inside the ring-shaped member 6.

The reinforcing member 19 is formed of a metal such as aluminum into a substantially cylindrical shape, and is adhered and fixed by an adhesive over substantially the entire side surface of the auxiliary column portion 11b. As a result, the strength of the sub-column portion 11b and the support frame 11 as a whole is increased, and when the piezoelectric element 13 is expanded by the application of voltage,
The rear frame of the support frame 11 is configured to suppress deformation, that is, vibration.

Further, since the reinforcing member 19 is adhered along the longitudinal direction of the sub strut portion 11b, a sufficiently wide contact area can be obtained. Further, in the conventional structure, the direction of deformation is the direction of peeling the adhesive, whereas in the structure of the present embodiment, the direction of deformation is parallel to the bonding surface, so it is fixed and held compared to electron beam welding. Even in the case of adhesive fixing with an adhesive having a weak force, it is possible to fix with a sufficiently strong fixing holding force.

Further, as shown in FIG. 5, the reinforcing member 19 is formed in a cross-sectional shape such that the distances between the respective sub-column portions 11b of the plurality of support frames 11 and the reinforcing member 19 are equal. This is to prevent the amount of the adhesive injected between the sub-column portion 11b and the reinforcing member 19 from being different due to the change in the distance between the sub-column portion 11b and the reinforcing member 19. This is because when the amount of adhesive is different, the force (expansion, contraction, etc.) generated in the adhesive when heat-curing or when heat generated during printing is applied is different, and the force acting on the printing unit 3 is also different. This is because stable operation of the print wire 4 cannot be obtained. FIG. 6 is an enlarged view of a part of FIG. 5, and when a voltage is applied to the piezoelectric element 13, the mover 14 moves upward in FIG. Here, the four-bar link mechanism member 21 is moved by the deformation of the lateral side portion 21c.
4 is translated in the same direction. The leaf spring 15 bends in the Y direction, whereby the arm 18 rotates and the print wire 4 moves to print. This operation tends to cause distortion in the support frame 11, but since the strength of the support frame 11 is increased by the reinforcing member 19, the support frame 11 is not deformed, and the print wire 4 is smoothly followed without deterioration. Moving.

The reinforcing member may be formed in a hollow shape. When the reinforcing member is formed in a hollow shape, the reinforcing member and the support frame may be fixed from the inside by electron beam welding or screwing.

3 and 4 show a second embodiment of the present invention.
The same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the connecting member 22 for connecting the main strut portion 11a and the sub strut portion 11b in the above embodiment is omitted.

As described in Japanese Patent Application Laid-Open No. 2-30547, the link mechanism member 21 is provided with the auxiliary column portion 11b and the mover 14.
Placing the link mechanism member 21 between the leaf spring 1
It is effective to place it near the leaf springs 15 and 16 while avoiding interference with the leaf springs 15 and 16. Further, the connecting member 22 is effective in preventing the free end of the sub strut 11b from opening with respect to the main strut 11a by the moving force of the mover 14.

By omitting the connecting member 22 as shown in FIG. 4, the mover 14 can be shortened by the width W (FIG. 2) of the connecting member 22. (The mover 14 is formed to have a small thickness in the direction perpendicular to the paper surface in order to avoid interference with the connection member 22, and without the connection member 22, the upper end of the piezoelectric element 13 thicker than the mover 14 is attached to the link mechanism member. 21.) As a result, the length of the printing unit 3 is reduced.

As shown in FIG. 3, the reinforcing member 19 has the sub-column portion 1
By being fixed to the side surface in the longitudinal direction of 1b with the adhesive 19b, it is possible to prevent the sub strut portion 11b from opening in the r direction with respect to the main strut portion 11a. To further ensure this, the sub-reinforcing member 19a may be bonded near the link mechanism member 21. Both reinforcing members 1
The 9 and 19a can be manufactured integrally.

It goes without saying that the reinforcing member 19 has the same effects as the above-mentioned embodiment.

The rear cover 30 is attached so as to cover the outside of the printing unit 3, and suppresses noise generated when the piezoelectric element 13 is driven. A gap between the rear cover 30 and the printing unit 3 is filled with heat-radiating silicon rubber 31, so that the heat generated by driving the piezoelectric element 13 can be absorbed by the rear cover 30.
Heat is radiated from the print head to prevent the print head temperature from rising.

The lead wire of the terminal 12 is connected to the wiring board 45 fixed to the rear surface of the rear cover 30.

[0032]

As described above, in the dot impact print head device of the present invention, the entire print head can be downsized and the strength of the print head can be increased, and the deformation of the print unit can be suppressed when the print wire is driven. The printing operation can be performed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a dot impact print head device according to a first embodiment of the present invention.

FIG. 2 is a side view showing only the printing unit of the above embodiment.

FIG. 3 is a sectional view of a dot impact print head device according to a second embodiment of the present invention.

FIG. 4 is a side view showing only the printing unit of the above embodiment.

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

6 is a partially enlarged view of FIG.

FIG. 7 is a sectional view of a conventional dot impact print head device.

[Explanation of symbols]

 1 Front Cover 3 Printing Unit 4 Printing Wire 6 Ring-shaped Member 9 Center Space 11 Support Frame 11a Main Support 11b Sub Support 13 Piezoelectric Element 19 Reinforcement 21 21 Four-Link Mechanism Member

Claims (9)

[Claims] 1. A piezoelectric element that expands and contracts when a voltage is applied,
A plurality of printing units in which a motion transmitting mechanism for transmitting the expansion and contraction of the piezoelectric element to a printing wire for stamping a printing medium are supported by a support frame extending in the longitudinal direction of the piezoelectric element, and the plurality of printing units. A support member that is arranged radially and fixes one end in the longitudinal direction of the support frame of the printing unit, and a support member that is arranged in the central space portion of the printing unit that is arranged radially and extends along the longitudinal direction of the support frame of each printing unit. A dot impact print head device comprising a reinforcing member having rigidity for fixing side surfaces. 2. The support frame according to claim 1, wherein the support frame supports a base portion for supporting one end of the piezoelectric element, and main strut portions and sub strut portions extending from the base portion along both sides of the piezoelectric element in a direction of expansion and contraction thereof. Is formed in a substantially U-shape, and the main strut is fixed to the support member at one end on the side opposite to the base, and the side surface along the longitudinal direction of the sub strut is fixed to the reinforcing member. Dot impact print head device. 3. The dot impact print head device according to claim 1, wherein the support member has a ring-shaped member, and each of the print wires is located inside the ring-shaped member. 4. The dot impact printing according to claim 3, wherein the support member further has a front cover having a substrate portion that supports the ring-shaped member and a cylindrical portion that supports the print wire at the center thereof. Head device. 5. The dot impact print head device according to claim 1, wherein the support frame of each print unit is adhesively fixed to the reinforcing member with an adhesive. 6. The piezoelectric element according to claim 2, further comprising a mover at the other end of the piezoelectric element, the mover being coupled to the motion transmitting mechanism, and the mover being provided between the mover and the sub-column portion. Dot impact print head device provided with linking means for guiding substantially parallel to the expansion and contraction direction of the. 7. The motion transmission mechanism according to claim 6, wherein the pair of leaf springs are respectively fixed to the opposing surfaces of the main support column and the mover, and one end is fixed to the free ends of both leaf springs. And a dot impact print head device comprising an arm having the print wire fixed to the other end. 8. The dot impact print head device according to claim 6, wherein the sub strut is fixed to the reinforcing member near the link means. 9. The dot impact print head device according to claim 1, wherein a cross section of the reinforcing member has a shape such that distances between the plurality of support frames and the reinforcing member are uniform.