JPH0640119A - Printing head device - Google Patents

Abstract

PURPOSE:To prevent a leak of a noise in a dot impact printing head and enhance an accuracy in mounting a head body on a printing apparatus support body. CONSTITUTION:A plurality of printing apparatuses 3 each driving a printing wire 7 by a piezoelectric element 10 are radially arranged and fixed on a ring- form support body 4. Vibration isolating bodies 23 having a U-shaped cross section are mounted on insertion parts 21 projected at four peripheral corners of the support body 4. L-shaped fastening parts 22 are projected at four points on the rear surface of a base part 1a of a head body 1. By rotating the support body 4, the vibration isolating bodies 23 and the insertion parts 21 are inserted into the fastening parts 22. At each corner, the fastening part 22, the vibration isolating body 23, and the insertion part 21 are fixed to each other by a positioning pin 20 penertating them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a dot impact print head device in which a print wire is driven in and out by a print mechanism having a driving means such as a piezoelectric element which expands and contracts when a voltage is applied, or an electromagnetic solenoid. More specifically, the present invention relates to a structure for preventing noise of a print head of this type.

[0002]

2. Description of the Related Art As a drive means for a print wire in a dot impact print head, there has been known, for example, Japanese Patent Laid-Open No.
There are an electromagnetic solenoid type as disclosed in JP-A-2-236759, and one using an electrostrictive element such as a piezoelectric element as in JP-A-2-130153.
Since electric energy is applied to these driving means and converted into mechanical motion, various noises such as vibration noise are emitted from the driving means and the operating portion of the printing mechanism. In order to prevent the noise and protect the printing mechanism and the like, the print head is generally provided with a cover body for covering the printing mechanism.

On the other hand, since it is difficult to directly assemble a printing unit in which the printing wire, the driving means and the printing mechanism are assembled in advance to a plurality of head main bodies, the applicant of the present invention has previously filed Japanese Patent Application No. No. 241363, the printing units are radially fixed to one surface of a ring-shaped support by screwing or the like in advance, and the support is brought into contact with the back surface of the head body via a vibration-proof material. , I proposed to screw the head body and the support.

[0004]

By the way, during the assembly work of the print head, in order to prevent the phase arrangement relationship (the order of the arrangement of the print wires, etc.) of the print wires with respect to the head body in the plurality of print units from being disturbed, A positioning hole is formed in the head body and the support body, and a positioning pin made of metal is passed through the hole.

In this case, as described above, even if there is a vibration isolating member interposed between the support and the head main body, the vibration generated by the printing mechanism or the driving means is positioned from the support during the printing operation. Since it is transmitted to the head main body through the pin, there is a problem that the noise prevention effect is reduced.
Further, when a plate-shaped vibration isolating member is inserted between the ring-shaped support body and the head main body, if the support body and the head main body are screwed at a plurality of points, the tightening force of the screw at each position Due to the variation of the above, the degree of compressive deformation of the inserted vibration isolating member varies, and it becomes difficult to attach the support body in parallel to the head main body. As a result, the degree of protrusion of the print wire protruding from the nose portion of the head main body also varies, so it is necessary to readjust it in order to prevent defective printing, and it takes time to assemble the print head. There was a problem.

It is an object of the present invention to solve these problems and to provide a print head device which is highly effective in reducing noise and which is easy to assemble the print head.

[0007]

To achieve the above object, according to the present invention, a plurality of printing units for driving a printing wire by a driving means are radially arranged and fixed on a ring-shaped support to fix the printing wire. In the print head provided so as to project from the head main body, the support body is formed with the insertion portions of the positioning pins so as to project radially outward of the support body at appropriate intervals along the outer periphery thereof, An engaging portion having an L-shaped cross section that holds the back surface of the insertion portion of the support body when the support body is rotated about its central axis is provided on the facing portion of the head body with the support body, A vibration-proof body is inserted between the insertion portion and the locking portion, and these are fixed through the positioning pins.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will now be described. The basic structure of the print head of this embodiment is shown in FIG. A plurality of (in the embodiment, 2) radially arranged via a metal ring-shaped support 4 attached to the back side of the rectangular base 1a.
It is composed of four printing units 3 and a cover body 2 that covers the group of the printing units 3. In this embodiment,
The head body 1 and the cover body 2 are made of aluminum alloy.

A hollow cylindrical nose portion 8 projecting from the base portion 1a of the head body 1 to the front surface is provided with a predetermined number of guide plates 9 for moving and guiding the print wires 7 in each print unit 3. The tip of the print wire 7 is configured to project and retract from the tip of the nose portion 8. Each printing unit 3
Is attached to the front end of the piezoelectric element 10 formed by bonding piezoelectric ceramics in a laminated shape, and is attached to the front end of the piezoelectric element 10 to expand the expansion and contraction movement of the piezoelectric element 10 and transmit it to the print wire 7. The printing mechanism 11 includes a printing mechanism 11 and a support frame 12 that extends rearward from the back surface of the head body 1 to support the printing mechanism 11 and the piezoelectric element 10. The support frame 12 is integrally formed in a U-shape by a main strut portion 12a, a sub strut portion 12b, and a rear end portion 12c so as to surround both sides in the longitudinal direction and the rear end portion of the piezoelectric element 10. The sub-column portion 12b may be fixed to the rear end portion 12c by brazing.

When charged by applying a voltage, the piezoelectric element 1
0 expands in the stacking direction (longitudinal direction) and contracts when discharged, and the piezoelectric element 10 contracts due to temperature rise. Therefore, the temperature compensator 13 having a positive temperature expansion characteristic that corrects for this, It is inserted between the rear end 12c of the support frame 12 and the rear end of the piezoelectric element 10 and fixed by an adhesive or brazing.

The printing mechanism 11 has an arm 14 which is formed by brazing the base of the printing wire 7 to the tip thereof and which has a substantially triangular shape in a side view.
And a plate-shaped first leaf spring and a second leaf spring extending in parallel rearward in the longitudinal direction of the main strut portion 12a, and a rigid connecting portion that connects the tip ends of both leaf springs to each other in a side view substantially "Π". It is composed of a character-shaped spring body 15 and a four-node link mechanism member 19 described later, and the connecting portion is fitted and fixed to the base end portion of the arm 14 by brazing or the like. The base end of the first leaf spring is brazed and fixed to the side surface of the main strut portion 12a, while the second end
The base end portion of the leaf spring is fixed to the movable element 18 that contacts the front end surface of the piezoelectric element 10 in a pressed state by brazing or the like.

A four-node link mechanism member 19 made of an elastic material such as a spring plate is provided so as to straddle the other side of the mover 18 and the sub strut part 12b. Although not shown, a notch hole having a substantially H-shape in a side view is formed in the wide side plate portion of each of the left and right wide side plate portions. When fixed to the front and back sides by spot welding (also possible by brazing), when the piezoelectric element 10 expands and contracts by applying a voltage, the left and right wide side plates of the four-node link mechanism member 19 elastically deform into a parallelogram shape in side view. The movable element 18 is configured to be movable in parallel along the longitudinal direction of the positionally fixed sub-column portion 12b.

In this way, if the mover 18 is configured to move in parallel along the longitudinal direction of the sub strut portion 12b, in other words, linearly in the longitudinal direction of the piezoelectric element 10, the laminated bonding of piezoelectric ceramics is performed. Bending force does not act on the surface, and the laminated portion and the adhesive surface do not peel off accidentally. Then, the front surface of the main support column 12a in each of the printing units 3 radially arranged on the ring-shaped support body 4 is aligned with the back surface of the support body 4 and fixed by brazing or screws (not shown). To do.

The support 4 is formed with insertion portions 21 of the positioning pins 20 which will be described later so as to project radially outward of the support 4 at appropriate intervals along the outer periphery thereof. In the embodiment, as shown in FIG. 2, the support 4 is formed in a substantially rectangular shape, and the four corners thereof are the insertion portions 21 having the wall thickness T1. On the other hand, on the back surface of the base portion 1a of the head main body 1, a cross section for holding the back surface of the insertion portion 21 of the support body 4 together with the vibration isolator 23 when the support body 4 is rotated around its central axis. Four L-shaped locking portions 22 are provided so as to project. The height dimension from the base portion 1a to the inner surface 22a of the locking portion 22 is T2. Anti-vibration body 23 made of anti-vibration rubber and having a U-shaped cross section
Is clamped in such a manner that each of the four insertion portions 21 holds the edge side, and is fixed in advance with an adhesive. Anti-vibration body 2
The thickness of 3 is the thickness of the engaging portion 22 with the insertion portion 21 sandwiched therebetween.
Is approximately equal to or slightly thicker than the height. Positioning holes 24, 25, and 26 through which the positioning pin 20 can pass are formed in the base portion 1a of the head body 1, the locking portion 22, the insertion portion 21, and the vibration isolator 23.

With this configuration, the base portion 1a of the head body 1
When the support body 4 is rotated in the direction of arrow A in FIG. 2 with one side of the vibration-proof body 23 of the support body 4 being in contact with the back side of the support body 4, as shown in FIG. Stop 2
It is possible to insert the insertion portion 21 and the vibration isolator 23 into the 2 from the lateral direction. At this time, when the vibration isolator 23 is inserted in a slightly compressed state, the locking portion 22, the base portion 1a and the insertion portion 21 are inserted.
No rattling occurs between the vibration damping member 23 and the vibration isolator 23, and the parallelism between the base portion 1a and the support body 4 is maintained when the vibration isolator 23 is inserted and locked in the locking portion 22. Can be held. When the positioning holes 24, 25, 26 of these three members are aligned with each other, the positioning pin 20 is penetrated, so that the supporting body 4 and the head main body 1 can be positioned and at the same time the fixing work of both can be completed.

As shown in FIG. 5, the inner surface 22a of the locking portion 22 having an L-shaped cross section is inserted through the insertion portion 21 and the vibration isolator 2.
3 is formed so as to be high on the insertion side and low on the locking side, the insertion work becomes extremely easy, and the locking part 22 compresses the vibration isolator 23 without rattling. Will be easier. Moreover, the parallelism between the base portion 1a and the support body 4 can be maintained when the vibration isolator 23 is inserted and locked in the lock portion 22.

A metallic ring-shaped reinforcing member 28 is fixed to the rear end surface of the support frame 12 of the printing units 3 arranged in a radial pattern by beam welding or the like to prevent deformation of each support frame 12 during printing operation. It is configured to reduce. A terminal component 29 electrically connected to the external terminal of the piezoelectric element 10 in each of the printing units 3,
It is attached to the rear end of each support frame 12, the front end of the terminal component 29 is penetrated through the bottom plate 2a of the cover body 2 and electrically connected to the printed board 30 on the outer surface, and the piezoelectric element 10 operates at a predetermined timing. Thus, the drive signal is transmitted from the control device of the printer.

In this structure, during a normal printing operation, when the piezoelectric element 10 is extended along the longitudinal direction by applying a voltage, a substantially midway portion in the longitudinal direction of the first leaf spring fixed to the main support column 12a is formed. The spring body is oscillated and displaced so as to be the center of rotation, and the displacement amount is transferred to the arm 1 via the connecting portion.
4, the print wire 7 is driven so as to protrude from the nose portion 8.

The silicone rubber 31 (see the alternate long and short dash line in FIG. 1) as a heat radiating medium filled in the inner space surrounded by the cover body 2 includes the support frame 12 and the piezoelectric element 10.
The heat generated by driving the piezoelectric element 10 may be transmitted to the cover body 2 by contacting the side surface of the cover body 2. And
The vibration sound generated by the driving of the printing mechanism 11 due to the expansion and contraction of the piezoelectric element 10 is transmitted to the support body 4. However, between the base portion 1a of the head body and the support body 4, the locking portions 22 are provided. Since the vibration isolator 23 is interposed, it is possible to prevent the vibration from being transmitted to the head body 1 side, and there is an effect of preventing noise of the print head.

Instead of fixing the vibration isolator 23 to the insertion portion 21 of the support 4 in advance, the vibration isolator 23 may be fixed in advance to the locking portion 22 side with an adhesive or the like. . It goes without saying that the present invention can also be applied to a print head that uses another type of drive means such as an electromagnetic solenoid as the drive means for the print wire.

[0021]

As described above, according to the present invention, a plurality of printing units for driving the printing wires by the driving means are radially arranged and fixed on the ring-shaped support, and the printing wires are head main body. In the print head provided so as to protrude from the head, the insertion portions of the positioning pins are formed on the support body at appropriate intervals along the outer periphery of the support body so as to protrude outward in the radius of the support body. An engaging portion having an L-shaped cross section that holds the back surface of the insertion portion of the support body when the support body is rotated about its central axis is provided on the surface of the main body facing the support body. Since a vibration-proof body is inserted between the locking portion and the locking portion and these are fixed through by positioning pins, when the support body is rotated around its central axis, it is inserted at a plurality of positions in the support body. Section and head body side It is easy to compress the amount of each isolator in between the engaging portion of the plurality of locations a substantially constant, and variations also hardly occurs. Therefore, in the work of attaching the support body to the head body, the accuracy of the parallelism between the head body and the support body can be improved as compared with the conventional screw fastening, and the work for that purpose can also be performed by locking the head body. Since the support body is simply rotated in parallel with respect to the portion and then the positioning pin is driven in, the work of assembling the print head is simplified.

Then, during the printing operation, the transmission of the vibration generated in the printing unit from the support to the head main body is blocked by the vibration isolator at the engaging portion. Therefore, it is possible to effectively prevent noise from leaking outside the print head.

[Brief description of drawings]

FIG. 1 is a side sectional view of a print head.

FIG. 2 is a view seen from the back surface side of a support.

FIG. 3 is an enlarged explanatory view of a main part of FIG.

FIG. 4 is a perspective view of a locking portion, an insertion portion, and a vibration isolator.

FIG. 5 is a diagram showing another embodiment as seen from the arrow VV of FIG.

[Explanation of symbols]

 1 Head Main Body 1a Base 2 Cover Body 3 Printing Unit 4 Support 7 Printing Wire 8 Nose 10 Piezoelectric Element 12 Support Frame 20 Positioning Pin 21 Insertion Part 22 Locking Part 23 Vibration Isolator

Claims (1)

[Claims] 1. A print head comprising a plurality of print units, each of which drives a print wire by a driving means, is radially arranged and fixed to a ring-shaped support, and the print wires are provided so as to protrude from a head body. The support body is formed with insertion portions of the positioning pins at appropriate intervals along the outer periphery of the support body so as to project outward in the radial direction of the support body. When the body is rotated around its central axis, a locking portion having an L-shaped cross section that holds the back surface of the insertion portion of the support is provided, and a vibration isolator is interposed between the insertion portion and the locking portion. A print head device characterized by being inserted and fixed by penetrating them with a positioning pin.