JPH0640122A - Dot impact printing head - Google Patents

Abstract

PURPOSE:To accelerate a heat dispersion and prevent a leak of a noise in a dot impact printing head. CONSTITUTION:At the back of a head body 1 formed by radially arraging a plurality of printing apparatuses 3 each driving a printing wire 7 by a piezoelectric element 10, the printing apparatuses 3 are enclosed by an inner cover body 2. An outer cover body 4 is fitted over the outer surface of a base part 1a of the head body and the outer peripheral surface of the inner cover body 2 so as to be spaced an appropriate gap 5. In the gap 5, a separation body 6 made of a material having a superior heat conductivity is interposed so as to abut on the wall surfaces of the inner and outer cover bodies. The separation body 6 having a long, hollow, tubular form is arranged in the gap 5 in spiral form and in coil form.

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 printing head in which a printing wire is driven in and out by a printing 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 and promoting heat dissipation of this type of print head.

[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.

However, there is a problem that heat is likely to be trapped in the cover body due to energy loss when converting the electric energy into mechanical energy. As a countermeasure against this, the present applicant has previously arranged an electromagnetic solenoid type printing mechanism in an internal space surrounded by a head main body and a cover body on the rear side in Japanese Patent Application No. 3-58766.
It has been proposed that the internal space is filled with a heat dissipation medium such as a silicone resin so as to come into contact with the driving means and the inner surface of the cover body, and a sound absorbing material is arranged so as to be partitioned from the heat dissipation medium.

[0004]

However, most of the members constituting the driving means and the printing mechanism are solids such as metals that easily transmit vibrations, and the heat dissipation medium and the sound absorbing material are also solids. There is a problem that vibration is easily transmitted to the head body and the cover body that are in contact with the member, and the noise reduction effect is small.

In order to reduce this noise, it is conceivable to mount an outer cover body on the outer side of the cover body with a gap, but since the air in the gap is a poor heat conductor,
Another problem occurs that the heat dissipation effect is reduced. SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems all at once, and to provide a print head with reduced noise and high heat dissipation effect.

[0006]

In order to achieve the above-mentioned object, the present invention provides a head main body comprising a plurality of printing mechanisms for driving a printing wire by a driving means, and a rear side of the head main body. In a dot impact print head comprising an inner cover body surrounding a drive means, an outer cover body is fitted on the outer surface of the head body and / or the outer periphery of the inner cover body so as to form a gap, A separator made of a material having excellent thermal conductivity is inserted in the gap, and the separator is formed so as to have a large number of compartments or hollow portions for partitioning at least the gap space into the inside and the outside. It was done.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment embodying the present invention will be described. The basic construction of the print head of this embodiment is, as shown in FIG. 1, a head body 1 having a substantially circular shape in front view and an inner cover. The body 2, a plurality of printing units 3 radially arranged with respect to the head body 1 in a space surrounded by both, the outer surface of the inner cover body 2 and the outer surface of the plate-shaped base portion 1a of the head body 1 as appropriate. An outer cover body 4 arranged with a gap 5 between
The separator 6 is made of a material having excellent thermal conductivity and is inserted into the gap.

In this embodiment, the head body 1, the inner cover body 2 and the outer cover body 4 are made of aluminum alloy. A plurality of (24 in the embodiment) printing units 3 are attached to the head body 1.
The print wires 7 in each printing unit 3 are arranged in a hollow cylindrical nose portion 8 which is radially arranged via a ring body 16 which is attached to the rear surface side of the base portion 1a of the head body 1 and which projects from the base portion 1a of the head body 1 to the front surface. A certain number of guide plates 9 for moving and guiding
Is built in, and the tip of each printing wire 7 is configured to project from the tip of the nose portion 8.

Each printing unit 3 is mounted on the front and rear piezoelectric elements 10 formed by laminating piezoelectric ceramics in a laminated shape, and at the front end of the piezoelectric elements 10 to expand and contract the movement of the piezoelectric elements 10 for printing. Printing mechanism 1 for transmitting to the wire 7
1 and a support frame 12 extending rearward from the back surface of the head body 1 for supporting the printing mechanism 11 and the piezoelectric element 10. The support frame 12 is the piezoelectric element 10
The main strut portion 12a, the sub strut portion 12b, and the rear end portion 12c are integrally formed in a U shape so as to surround both sides in the longitudinal direction and the rear end portion. 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 portion 12c of the support frame 12 and the rear end of the piezoelectric element 10 and fixed by an adhesive. The printing mechanism 11 has a substantially triangular arm 14 in side view formed by brazing the base of the printing wire 7 to the tip thereof, and a plate-shaped first extension extending in parallel to the rear side in the longitudinal direction of the main support column 12a.
A spring body 1 having a substantially "Π" shape in a side view, which includes a leaf spring, a second leaf spring, and a rigid connecting portion that connects the ends of the leaf springs.
5 and a four-bar 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 portion of the first leaf spring is brazed and fixed to the side surface of the main strut portion 12a, while the base end portion of the second leaf spring is the same as the mover 18 that contacts the front end face of the piezoelectric element 10 in a pressed state. It is fixed by brazing.

A four-node link mechanism member 19 made of an elastic material such as a spring plate is arranged so as to straddle the other side of the mover 18 and the sub-column 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, to move linearly in the longitudinal direction of the piezoelectric element 10, 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. A terminal component 20 electrically connected to the external terminal of the piezoelectric element 10 in each of the printing units 3 is attached to the rear end of each support frame 12, and the tip of the terminal component 20 is attached to the bottom plate portion 2a of the inner cover body 2.
And is electrically connected to the printed board 21 on the outer surface, and a drive signal is transmitted from the controller of the printer so that the piezoelectric element 10 operates at a predetermined timing.

In a normal printing operation, when the piezoelectric element 10 is extended along the longitudinal direction by applying a voltage, the center of rotation of the first leaf spring fixedly attached to the main strut portion 12a is a substantially midway portion in the longitudinal direction. The spring body swings and displaces as
The displacement amount is enlarged by the arm 14 via the connecting portion, and the printing wire 7 is driven so as to protrude from the nose portion 8.

The silicone rubber 22 filled in the inner space surrounded by the inner cover body 2 is formed by the support frame 12
Also, the heat generated by driving the piezoelectric element 10 by contacting the side surface of the piezoelectric element 10 is transferred to the inner cover body 2. Next, the separating body 6 inserted in the gap 5 between the inner cover body 2 and the outer cover body 4 is inserted.
Will be described. As shown in FIG. 1, the first embodiment of the separating body 6 is formed by a thin pipe tube or foil tube made of a material having a high thermal conductivity such as a long pipe-like long aluminum or copper material. It is a thing. In the gap between the base portion 1a of the head body 1 and the front plate 4a of the outer cover body 4, the separating body 6 is spirally arranged, and at the cylindrical gap portion between the outer cover body 4 and the inner cover body 2, The separating body 6 is wound around the coil, and the outer surface of the separating body 6 is interposed between the outer cover body 4 and the outer wall surfaces of the head body 1 and the inner cover body 2 so as to be sufficiently in contact with each other at any gaps. Insert it. In this case, the outer cover body 4 may be fitted after the separation body 6 is fixed to the outer surface of the base portion 1a of the head body or the outer surface of the inner cover body 2 with an adhesive or the like. Further, it is preferable that the adjacent separators 6 and 6 are also brought into contact with each other.

In this way, the heat generated from the piezoelectric element 10 and the like is transmitted through the silicone rubber 22 to the inner cover body 2.
To the outer cover body 4 via the separating body 6, so that the outer cover body 4 comes into contact with the outside air and radiates heat sufficiently. In this case, if the fins 23 for heat dissipation are formed on the outer surface of the outer cover body 4, the heat dissipation effect can be further enhanced.

The printing mechanism 1 by expanding and contracting the piezoelectric element
The vibration sound generated by driving 1 is relatively well transmitted to the inner cover body 2. However, at the gap between the inner cover body 2 and the base portion 1a of the head body 1 and the outer cover body 4, the vibration is transmitted to the separating body 6 and the air in the gap is vibrated, so that the outer cover body 4 is vibrated. Although the vibration sound is about to be transmitted, the separation body 6 has a thin plate-like hollow cylindrical shape (tubular shape).
Therefore, the outer cover body 4 functions as a vibration isolator.
The transmission of vibration sound to the head is reduced, and a quiet print head can be provided.

If the orifice walls are formed in the wall of the separation body 6 at appropriate intervals, the vibrations can be more effectively damped by the resistance of the air flowing through the orifice holes. Can be made. FIG. 2 shows a second embodiment of the separator, and the separator 30 in this embodiment is made of a material having good heat conductivity such as aluminum, and includes a partition plate portion 31 and
A fin portion 32 protruding from both front and back surfaces of the partition plate portion 31.
And having flexibility, the separator 30 is inserted in the gap 5 between the inner cover body 2 and the outer cover body 4, and the fin portion 32 is provided on the outer surface of the base 1a of the head body 1 and the inner cover. The outer surface of the body 2 and the inner surface of the outer cover body 4 are kept in contact with each other.
With this configuration, the partition plate portion 31 and the fin portion 32,
A large number of compartments that divide the space of the gap 5 into the inside and the outside are formed. In this case, the orifice holes 33 may be formed in the partition plate portion 31 at appropriate intervals.

The third embodiment shown in FIG. 3 is a flexible curved cross-section type separator 34 made of a material having good thermal conductivity such as aluminum, and the separator of the fourth embodiment shown in FIG. In No. 35, it is a wavy shape having a U-shaped cross section. The upper and lower end portions of the corrugated portions of the separating bodies 34 and 35 are inserted so as to abut against the wall surfaces of the outer cover body 4 and the inner cover body 2, respectively. These separators 3
4, 35 also form a large number of compartments for partitioning the gap 5 inside and outside.

The separator 36 of the fifth embodiment shown in FIG. 5 has a corrugated partition plate 3 having a corrugated cross section between the plate portions 37 and 38 on both front and back sides.
9 is sandwiched between the plate portion 37 and the inner cover body 2
And the other plate portion 38 is brought into contact with the wall surface of the outer cover body 4. In this case, the orifice holes may be formed in the intermediate partition plate 39 at appropriate intervals. In addition, a large number of substantially hemispherical independent hollow portions may be formed at regular intervals on one or both sides of the partition plate to form a separator.

In the case of the form having the plate portion 38 as in the fifth embodiment, this plate portion 38 may be configured to also serve as the inner cover body. Furthermore, as another example, the separators 6, 34, 35, 3 made of a material having excellent thermal conductivity are used.
6 and the like, the spring constant of the separator is set to be small when it is formed into a shape having spring elasticity in the cross section as shown in FIG. 1 or FIGS. .

For example, if the frequency of operation of the piezoelectric element 10 is 5 KHz, the inner cover body 2 vibrates at the frequency w, so that the outer cover body 4 also has the elastic separating members 6, 34 ,. It vibrates through 35 and 36.
Therefore, in order to prevent the outer cover body 4 from resonating and vibrating due to the forced vibration by the driving means such as a piezoelectric element, the frequency w of the forced vibration by the driving means and the natural frequency p of the outer cover body 4 are set. The spring constant of the separator is set so as to deviate from the point (resonance point) where the ratio (w / p) becomes 1 to the larger side.

It goes without saying that the present invention can also be applied to a print head using another type of drive means such as an electromagnetic solenoid as the drive means for the print wire.

[0023]

As described above, according to the present invention, the printing mechanism for driving the printing wire by the driving means is provided.
In a dot impact print head comprising a plurality of head bodies and an inner cover body surrounding the driving means on the rear side of the head body, an outer surface of the head body and / or an outer circumference of the inner cover body. In, the outer cover body is fitted so as to form a gap appropriately, and in the gap, a separator made of a material having excellent thermal conductivity is inserted.
The heat generated from the internal printing mechanism and drive means surrounded by the head main body and the inner cover body is transferred to the outer cover body through the heat-conductive separator that contacts the inner cover body and the head body. Since the heat is dissipated, the heat is not trapped inside the print head. Further, the separating body inserted in the gap between the head main body and / or the inner cover body and the outer cover body has a large number of compartments or hollow portions for partitioning at least the gap space into an inner side and an outer side. Since the vibration energy generated from the printing mechanism or the driving means is spent on the vibration of the air and the separator in the compartment or the hollow portion, and the vibration is quickly attenuated, the print head is formed. Therefore, it is possible to effectively prevent the noise from leaking to the outside.

[Brief description of drawings]

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

FIG. 2 is a sectional view of a second embodiment of the separator.

FIG. 3 is a sectional view of a third embodiment of the separator.

FIG. 4 is a sectional view of a fourth embodiment of the separator.

FIG. 5 is a sectional view of a fifth embodiment of the separator.

[Explanation of symbols]

 1 Head Main Body 2 Inner Cover Body 3 Printing Unit 4 Outer Cover Body 5 Gap 6,30, 34, 35, 36 Separator 7 Printing Wire 8 Nose Part 10 Piezoelectric Element 12 Support Frame 22 Silicone Rubber 31 Partition Plate Part 32 Fin Part 37 , 38 Plate portion 39 Partition plate

Claims (1)

[Claims] 1. A dot impact printing comprising a head body having a plurality of printing mechanisms for driving a printing wire by a driving means, and an inner cover body surrounding the driving means on the rear side of the head body. In the head, an outer cover body is fitted to the outer surface of the head main body and / or the outer circumference of the inner cover body so as to form a gap, and the gap is formed of a material having excellent thermal conductivity. A dot impact print head, characterized in that a plurality of compartments or hollow portions for partitioning at least the gap space inside and outside are provided.