JPH06297731A - Wire dot printing head - Google Patents

Abstract

PURPOSE:To keep impact force for printing almost constant, in a printing head driving a movable arm having a printing wire by a piezoelectric actuator to perform printing, by preventing secondary bound becoming large even when the stopper mechanism of the movable arm is abraded by executing printing over a large number of times. CONSTITUTION:The driving force of a piezoelectric actuator 33 is transmitted to a movable arm 32 through a spring member 35 and dot printing is performed by a printing wire 36 and, when the movable arm 32 returns to an initial position, the movable arm 32 is stopped by stopper mechanisms 37,38. The movable member 34 connected to the spring member 35 and the piezoelectric actuator 33 are bonded by a plastically deformable membrane member 40. Even when the stopper mechanisms 37,38 are abraded by printing for many years, the membrane member 40 becomes thin by secular plastic deformation and, therefore, the expansion of the gap between the stopper mechanisms can be corrected and secondary bound is prevented from becoming large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire dot type print head, and more particularly, a gap between a movable arm to which a print wire is connected and a stopper mechanism for receiving the backward movement of the movable arm is enlarged and attached to a piezoelectric actuator. The present invention relates to a plastic member that is prevented by plastic deformation.

[0002]

2. Description of the Related Art Conventionally, in a dot impact printer, a movable actuator supported by an elastic member is rotated and connected to a movable actuator supported by an elastic member due to expansion and contraction when a voltage is applied to a piezoelectric actuator made of a laminated body of piezoelectric elements. A print head is known in which the printed wire is projected to the platen side for dot printing. For example, the applicant of the present application discloses in Japanese Patent Laid-Open No. 2-137937 that the base end of the piezoelectric actuator is fixed to the base of a main frame that is substantially U-shaped in side view while the other end of the piezoelectric actuator is used as a movable body. Mounting, one leaf spring of the spring member is fixed to the main frame, the other leaf spring of the spring member is fixed to the movable body, and further, the movable arm is swingably supported by this spring member, and This movable arm is swung to the print position by extension deformation due to the application of voltage, and dots are printed via the print wire, while the piezoelectric actuator contracts and deforms so that the movable arm does not retract from the initial position. The stopper member regulates the swinging range and reduces the wear between the abutting portion of these movable arms and the stopper surface of the stopper member. It proposed a motion converter of the electric element.

[0003]

As described above, in the motion conversion device for the piezoelectric element proposed by the applicant of the present application,
When the movable arm returns to its original position after printing,
Since the contact portion of the movable arm is brought into contact with the stopper surface of the stopper member to prevent the movable arm from retracting from the initial position, for example, a large number of dot printings such as 100 million times and 200 million times are performed. The wear of the abutting portion of the movable arm and the stopper surface of the stopper member is unavoidable due to the execution of the above. Therefore, the gap (gap) between the abutting portion and the stopper portion is expanded, and the movable arm of each movable dot is printed. 2 in damping vibration
The next bounce increases. By the way, in this type of print head, since the next dot printing is generally executed at the timing of this secondary bounce, this large secondary bounce force is applied in each of the second and subsequent dot printings. Therefore, there is a problem that the printing wire collides strongly with the printing paper and the paper is apt to break.

It is an object of the present invention to provide a wire dot type print head capable of preventing paper breakage by a wire as much as possible even when dot printing is performed many times.

[0005]

According to another aspect of the present invention, there is provided a wire dot type print head comprising: a wire; a movable arm having a base end portion of the wire connected to one end portion; and a piezoelectric actuator including a laminated body of piezoelectric elements. , A wire dot type having a plurality of sets of dot printing mechanisms including a driving force transmission mechanism that transmits the driving force of the piezoelectric actuator to the movable arm and a stopper mechanism that receives the movable arm so that the movable arm does not retract from the initial position. In the print head, a plastic member capable of being plastically deformed by receiving a pressing force is interposed between each piezoelectric actuator and the driving force transmission mechanism, and the change rate of secular wear of the stopper mechanism that receives each movable arm and the plastic member It is configured so that the rate of change of plastic deformation over time is approximately equal.

Here, the plastic member can be configured in various modes such as a film member of an adhesive agent for bonding the piezoelectric actuator to the driving force transmission mechanism (claim 2).

[0007]

According to the wire dot type print head of the present invention, a pressing force is applied between the piezoelectric actuator formed of a laminated body of piezoelectric elements and the driving force transmission mechanism for transmitting the driving force of the piezoelectric actuator to the movable arm. Since a plastic member that can be plastically deformed is interposed, and the rate of change over time of the stopper mechanism that receives each movable arm is approximately equal to the rate of change over time of plastic deformation of the plastic member, The gap between each movable arm and the stopper mechanism widens due to the wear of the stopper mechanism due to the repeated printing, while the plastic member that is constantly subjected to the pressing force by the spring member provided in the driving force transmission mechanism Due to the plastic deformation, the movable arm 32 gradually moves its initial position to the stopper mechanism side via the driving force transmission mechanism,
As a result, even if printing is performed many times, the gap can be substantially maintained at the size that was originally provided.

As described above, although the dot printing is performed many times and the gap between each movable arm and the stopper mechanism is enlarged, the initial position of the movable arm is driven by the plastic deformation of the plastic member. By gradually moving to the stopper mechanism side via the transmission mechanism, the gap between the movable arm and the stopper mechanism can be substantially maintained at the initially set size, and the secondary bound of the movable arm can be prevented. Bounce force does not increase, and 2 of movable arm
When dots are printed at the next bounce timing, it is possible to prevent paper breakage due to the wire as much as possible.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is a case where the present invention is applied to a wire dot type print head print head provided in the dot impact printer 1 and provided with 24 print wires. First, the dot impact printer 1 will be briefly described. As shown in FIG. 1, a carriage 3 is supported in front of the platen 2 so as to be movable left and right by a guide shaft (not shown) parallel to the platen 2. The print head 6 of the wire dot printing system is mounted on the platen 2 on the platen 2.
It is attached opposite to. The carriage 3 is driven to reciprocate left and right by a carriage motor connected to a drive wire (not shown), and the platen 2 is rotationally driven via a line feed motor and a platen drive mechanism (not shown).

Next, regarding the print head 6, as shown in FIG.
A description will be given based on FIG. The print head 6 has a nose portion 25.
a front frame 25 having a and a cylindrical rear frame 26 having a bottom, an annular ring member 28 attached to the front frame 25 via an annular spacer 27 made of rubber, and attached to the ring member 28. 24 sets of dot printing mechanisms 30 are provided.
Will be described. The plate-shaped and substantially U-shaped side view support frame 31 is screwed to the ring member 28 at the base end thereof, and the tip end thereof is positioned immediately behind the plate-shaped movable arm 32 in the middle in the length direction. is doing.

The piezoelectric actuator 33, which is composed of a laminated body of piezoelectric elements, has a support portion 31a on the base end side of the support frame 31.
Is provided in the front-rear direction in a notch portion 31d between the stopper portion 31b and the stopper portion 31b on the front end side, and a front end portion of the attachment portion 31c between the support portion 31a and the stopper portion 31b has an adhesive (a plastic member is used). The corresponding end is adhered and supported by a similar adhesive 40. Here, the adhesive 40 is a plastic-based resin-based adhesive, and the piezoelectric actuator 33 is used.
The front side and the rear side of, respectively, are adhered with a thickness of, for example, 15μ.

On the other hand, the first spring 3 of the spring member 35 is provided at the end facing the notch 31d at the rear end of the support 31a.
5a is fixed, and the second spring 35b of the spring member 35 is fixed to the end of the movable body 34 corresponding to this end face. By the way, the spring member 35 is composed of first and second springs 35a and 35b facing each other, and a connecting portion 35c connecting the first and second springs 35a and 35b. A base end portion of a movable arm 32 radially arranged in the rear frame 26 is fixed, and a base end portion of a print wire 36 extending to the platen 2 through the nose portion 25a is fixed to a tip end portion of the movable arm 32. Is installed.

By the way, a predetermined pressing force (for example, 10 kg) is constantly applied to the left and right adhesives 40 in the direction of arrow A by the spring force of the spring member 35 via the movable body 34 and the piezoelectric actuator 33. Along with the spring member 35, the movable arm 32 has a gap g between the rear end of the stopper member 37 attached to the rear end of the stopper portion 31b and the front end of the contact member 38 attached to the movable arm 32.
It is arranged so as not to provide. The stopper member 37 and the contact member 38 form a stopper mechanism.

When a voltage is applied to the piezoelectric actuator 33, the piezoelectric actuator 33 expands and deforms by a predetermined length in the stacking direction, that is, the front-rear direction, so that the movable body 34 moves in the direction of arrow P. Then, only the second spring 35b moves rearward along the facing first spring 35a, and the spring member 35 bends outward in a curved shape as indicated by a two-dot chain line in FIG. As a result, the movable arm 32
2 generates a rotation moment in the counterclockwise direction in FIG. 2, and as shown by the chain double-dashed line in FIG.
At the same time that the tip of the print head rotates to the printing position where it moves in the platen 2 direction, the printing wire 36 moves in the platen 2 direction, and dot printing is performed via an ink ribbon (not shown). Here, when the piezoelectric actuator 33 is expanded and deformed, the piezoelectric actuator 33 is further connected to the piezoelectric actuator 33 via the movable body 34 as the spring force of the spring member 35 increases due to the movement of the movable body 34 in the arrow P direction. ,
A pressing force of 5 kg will be added.

On the other hand, when the voltage application to the piezoelectric actuator 33 is stopped, the piezoelectric actuator 3
Since 3 is contracted and deformed to the original state, the movable arm 32 returns to the original initial position and rotates via the movable body 34 and the spring member 35. At this time, the stopper mechanism allows the movable arm 32 to be received by the stopper member 37 so that the movable arm 32 does not retract from the original initial position by the stopper mechanism. By the way, after the series of printing operations by the piezoelectric actuator 33 is executed in this way, when the movable arm 32 returns and rotates to the original initial position via the spring member 35 as described above, the contact member is rotated. Since the stopper member 37 collides with the stopper member 37, a large number of printing operations are performed over a long period of time, so that both members 38 and 37 wear and the gap g increases.

When the gap g is enlarged, when the movable arm 32 is returned to the initial position and rotated after the first dot printing, the movable arm 32 is re-rotated due to the damping vibration due to the collision between the both members 38 and 37. The bounce force of the secondary bounce jumping out to the 2 side becomes large. Here, in general, when the dot printing is continuous, the next dot is printed at the timing of the secondary bound due to the previous printing operation. Therefore, the second dot is printed at the timing of the increased secondary bound. The impact force of the print wire 36 in the printing of each dot after the dot becomes large, and the breakage of the paper due to the print wire 36 easily occurs. Here, a driving force transmission mechanism is configured by the movable body 34, the spring member 35, and the like.

However, as described above, the left and right adhesive 4
A predetermined pressing force is constantly applied to 0 in the direction of arrow A by the spring force of the spring member 35, and the pressing force due to the extension deformation of the piezoelectric actuator 33 is added during dot printing, as shown in FIG. So that both the left and right adhesive 40
Under this pressing force, so-called creep phenomenon causes plastic deformation over time, and the thickness of both adhesives 40 gradually decreases. On the other hand, as described above, the gap g is, as shown by the two-dot chain line in FIG.
It is gradually expanded by 37 collisions.

By the way, the rate of change over time in wear of these members 38 and 37, that is, the rate of change over time in the gap g, is determined by experiments, while the rate of change in plastic deformation over time of the adhesive 40 is within this gap g. The type and amount of the adhesive 40 are determined by repeating the experiment so as to be approximately equal to the enlargement factor over time, and the determined adhesive 40 is applied to each of the adhesive surfaces. As a result, as the gap g expands, the movable arm 32 shows the initial position of the movable arm 32 via the movable body 34 and the spring member 35 by an arrow M in FIG. As described above, the gap g is gradually moved in the clockwise direction, and as a result, the gap g can be maintained in the state of the gap g initially provided without being greatly expanded.

As a result, the bounding force of the secondary bounce of the movable arm 32 does not increase, and the movable arm 3
When printing dots at the timing of the secondary bounce of 2,
It is possible to prevent the breakage of the paper due to the printing wire 36 as much as possible. Furthermore, since the adhesive 40 is only applied to the front and rear end surfaces of the piezoelectric actuator 33, the piezoelectric actuator 3
3 can be easily attached to the movable body 34 or the attachment portion 31c,
Moreover, the cost does not increase.

The adhesive 40 may be applied to only one of the front side and the rear side of the piezoelectric actuator 33. Instead of the adhesive 40, various plastically deformable film members may be used. You may use. The dot printing mechanism 30
It is needless to say that the present invention can be applied to various wire dot type print heads driven by piezoelectric actuators provided with 24 or more sets.

[0021]

As described above, according to the wire dot type print head of the first aspect, the plastic deformation occurs between the piezoelectric actuator and the driving force transmission mechanism for transmitting the driving force of the piezoelectric actuator to the movable arm. Since a possible plastic member is interposed and the rate of change over time of the stopper mechanism that receives each movable arm is made substantially equal to the rate of change over time of plastic deformation of the plastic member, it is possible to use multiple dots. Although the printing is executed and the gap between each movable arm and the stopper mechanism is expanded, the initial position of the movable arm is gradually moved to the stopper mechanism side via the driving force transmission mechanism due to the plastic deformation of the plastic member. When the movable arm is moved, the gap between the movable arm and the stopper mechanism can be substantially maintained at the initially set size, and the secondary bound of the movable arm can be achieved. Without the bouncing force increases, when dot printing at the timing of the secondary bounce of the movable arm, the paper torn by the wire can be prevented as much as possible.

According to the wire dot type print head of the present invention, since the plastic member is composed of an adhesive film member that adheres the piezoelectric actuator to the driving force transmitting mechanism, the piezoelectric actuator can be easily used as the driving force transmitting mechanism. It can be attached to a plastic member and the cost of the plastic member can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a main part of a print head.

FIG. 2 is a side view of an enlarged longitudinal section of a main part of the print head.

FIG. 3 is a diagram showing the aged plastic deformation of the adhesive.

FIG. 4 is a diagram showing a secular change in a gap.

[Explanation of symbols]

 30 dot printing mechanism 32 movable arm 33 piezoelectric actuator 34 movable body 35 spring member 36 printing wire 40 adhesive

Claims (2)

[Claims] 1. A wire, a movable arm whose base end is connected to one end, a piezoelectric actuator formed of a laminated body of piezoelectric elements, and a driving force for transmitting the driving force of the piezoelectric actuator to the movable arm. A wire dot type print head comprising a plurality of sets of dot printing mechanisms including a transmission mechanism and a stopper mechanism that receives the movable arm so that the movable arm does not retract from the initial position. , A plastic member capable of being plastically deformed by receiving a pressing force is interposed, and a change rate of aged wear of a stopper mechanism that receives the movable arms and a change rate of aged plastic deformation of the plastic member are substantially equal to each other. A wire dot type print head having the above structure. 2. The wire dot type print head according to claim 1, wherein the plastic member is made of an adhesive film member that adheres the piezoelectric actuator to the driving force transmission mechanism.