JPH0691985A - Dot impact printing head - Google Patents

Abstract

PURPOSE:To prompt dissipation of heat in a dot impact printing head and prevent leakage of noise from occurring. CONSTITUTION:A printing unit 3 which drives a printing wire 7 using a piezoelectric element 10 is encircled by a heat radiating cover 4 consisting of a front cover piece 4b and a rear cover piece 4a on the rear of a head substrate 1 on which so many pieces of printing wire 7 are arranged. The rear cover piece 4a is filled with a silicone rubber heat transfer member 24 which comes in contact with the support frame or the piezoelectric element side 10 of the printing unit. In addition, the front edge of the rear cover piece 4a and the rear edge of the front cover piece 4b are connected to a ring-shaped vibration damping member 25 of silicone rubber. Further, the front of a head substrate 1 is covered by a heat-conductive elastic member 26 of silicone rubber and the peripheral side of the head substrate 1 is isolated from the front cover piece 4b.

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, an electromagnetic solenoid type drive means such as disclosed in Japanese Patent Laid-Open No. 62-236759 has been used. , Japanese Patent Laid-Open No. 2-130153, which uses an electrostrictive element such as a piezoelectric element. 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.

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 radiation medium and the sound absorbing material are also solids, so that they are in contact with these solid members. The vibration is easily transmitted to the cover body and the like, and when the vibration of the cover body is directly transmitted to the head main body having a large front area, the head main body easily vibrates greatly, so that there is a problem that the noise reduction effect is small. .

In order to reduce such noise, it is conceivable to use the printer as a whole in a soundproof box. However, this causes a new problem that the entire printer is bulky and the cost is increased. To do.
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 object, the dot impact printing head of the present invention has a plurality of printing mechanisms for driving a printing wire by a driving means, which are arranged on the rear side of the head substrate. In a dot impact print head configured to move the print wire forward from inside a hollow nose portion that projects forward from the heat dissipation cover that fits the rear side of the head substrate, It is composed of a surrounding rear cover body and a front cover body that surrounds the outer periphery of the printing mechanism, and connects the rear cover body and the front cover body through a vibration isolating member, while connecting the head substrate and the front cover body. It is connected through a heat conductive elastic body.

In this case, the heat conductive elastic body connecting the head substrate and the front cover body may be formed so as to cover the front surface and the outer peripheral side surface of the head substrate.

[0008]

EXAMPLE Next, an example in which the present invention is embodied will be described. The basic structure of the print head of this example is, as shown in FIG. 1, a head substrate 1 having a substantially circular shape in front view, and the head. A hollow nose portion 2 that protrudes forward in a substantially central portion of a front surface of a substrate 1, a plurality of printing units 3 radially arranged on the rear side of the head substrate 1, and a head substrate so as to surround a group of the printing units 3. 1 and a heat dissipation cover 4 disposed on the rear side of the heat dissipation cover 1. The heat dissipation cover 4 is composed of a bottomed rear cover body 4a and a cylindrical front cover body 4b arranged in front of the bottom cover body 4a so as to approach the head substrate 1. Substrate 1 and heat dissipation cover 4
Is made of a metal having good thermal conductivity, for example, an aluminum alloy.

To the metallic ring body 5 mounted on the back side of the head substrate 1 via the screws 28 and a plurality of vibration-proof discs 29,
The front surfaces of the support frames 12 of the plurality (24 in the embodiment) of the printing units 3 are fixed by screws 30 (see FIG. 2). A hollow cylindrical nose portion 2 protruding from the front surface of the head substrate 1 is provided with a predetermined number of guide plates 6 for moving and guiding the printing wires 7 in each printing unit 3,
The tip of each print wire 7 is configured to project and retract from the tip of the nose portion 2.

Each printing unit 3 is attached to the front and rear longitudinal piezoelectric elements 10 formed by laminating piezoelectric ceramics in a laminated form, and is attached to the front ends of the piezoelectric elements 10 to expand and contract 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 linkage mechanism member 16 to be 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 movable element 17 that contacts the front end face of the piezoelectric element 10 in a pressed state. It is fixed by brazing.

The four-node link mechanism member 16 made of an elastic material such as a spring plate is disposed so as to straddle the other side of the mover 17 and the sub-column part 12b. A hole 18 having a substantially H shape in side view is formed in the wide side plate portion of the hole 1.
When the piezoelectric element 10 expands and contracts when a voltage is applied, the left and right wide side plate parts are fixed to the front and back side surfaces of the auxiliary column part 12b and the front and back side surfaces of the movable element 17 by spot welding (brazing is possible). The left and right wide side plates of the four-bar linkage member 16 are elastically deformed into a parallelogram shape in side view so that the mover 17 can move in parallel along the longitudinal direction of the position-fixed sub-column 12b. It is a thing.

In this way, if the mover 17 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. 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 leading end of the terminal component 20 is connected to the bottom plate portion of the rear cover body 4a and the electrical components. A drive signal is transmitted from the controller of the printer so that the insulating plate 22 is penetrated and electrically connected to the outer printed board 21 so that the piezoelectric element 10 operates at a predetermined timing.

In a normal printing operation, when the piezoelectric element 10 extends along the longitudinal direction by the application of a voltage, the center of rotation of the first leaf spring fixed to the main strut portion 12a is a substantially midway portion in the longitudinal direction. As described above, the spring body 15 is oscillated and displaced, and the displacement amount is enlarged by the arm 14 via the connecting portion, and the print wire 7 is driven so as to protrude from the nose portion 2. The support frames 12 of the printing units 3 arranged in a radial pattern are fixed to an annular reinforcing member 23 arranged across the rear end of the printing unit 3 with an adhesive and / or a screw. Of the printing wire 7 by elastic deformation of the support frame 12 due to single or multiple simultaneous operation of
The influence of the operation error of is reduced. Also,
By interposing a stopper 19 between the sub strut portion 12b and the arm 14, the retracted position of the arm 14 during driving is regulated and extra vibration is eliminated.

Next, the noise prevention and vibration prevention means of the present invention will be described. The mover 17 in the radially arranged printing unit 3 and the printing mechanism 11 in front of it
In the inner space surrounded by the rear cover body 4a so as to contact the substantially rear half peripheral surface of the support frame 12 and the substantially rear half peripheral surface of the piezoelectric element 10 with good heat conductivity such as silicone rubber. A front cover body 4b surrounding a space not filled with the heat conducting member 24 and a front end edge of the rear cover body 4a. Are continuously provided via a vibration-proof member 25 such as a silicone rubber formed in a ring shape.

The front edge of the front cover 4b and the head substrate 1 are made of an elastic material such as silicone rubber, which has good thermal conductivity and vibration damping performance. To be installed continuously. At this time, as shown in FIG. 1, the heat-conducting elastic body 26 is formed of the metal front with respect to the outer peripheral surface of the ring body 5 and the outer peripheral surface of the head substrate 1 which connect the front portions of the support frame 12. An interposing portion 26a is formed so that the partial cover body 4b does not come into direct contact, and further, in the embodiment of FIG.
The cover shape is formed integrally so as to cover (remaining).

As a result, the heat generated by driving the piezoelectric element 10 is transferred to the rear cover body 4a via the heat conducting member 24 in contact with the side surfaces of the support frame 12 and the piezoelectric element 10, and from the outer surface thereof to the outside atmosphere. Is radiated to. In this case, if a large number of heat radiation fins are provided on the outer surface of the rear cover body 4a, the heat radiation effect can be further promoted. Heat is also transferred from the rear cover body 4a to the front cover body 4b via the vibration isolator 25, and the heat transferred from the front side of each piezoelectric element 10 via the ring body 5 is transferred to the ring body 5a. Is transmitted to the heat conductive elastic body 26 through the head substrate 1, contacts the outside air, and can radiate heat from the front portion of the print head to the outside.

On the other hand, the vibration caused by the driving of the printing unit 3 is mainly caused by the expansion and contraction of the piezoelectric element 10.
2 and the vibration of the printing mechanism 11 are transmitted to the rear cover body 4a through the heat conducting member 24, but the heat conducting member 24 is elastic such as silicone rubber having a vibration damping performance. When it is a body, it has a vibration-proof effect at that location. In addition, from the support frame 12 to the ring body 5
The vibration transmitted to the head substrate 1 side via the heat conduction elastic body 26 covering the front portion and the outer peripheral surface can effectively prevent the vibration transmitted to the outside as noise.

As another embodiment, the heat conducting elastic body 26 may be formed only on the ring-shaped connecting portion 26a between the outer peripheral surface of the head substrate 1 and the front edge of the front cover body 4b. Further, as the heat conducting member 24, the vibration isolating member 25 and the heat conducting elastic body 26, a synthetic resin material other than silicone rubber having a vibration isolating effect and good heat conduction can be used.

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

[0021]

As described above, according to the present invention, a plurality of printing mechanisms for driving the printing wires by the driving means are arranged on the rear side of the head substrate, and the printing mechanism has a hollow shape protruding forward from the head substrate. In a dot impact print head configured to move the print wire forward from inside the nose portion, a heat dissipation cover that fits the rear side of the head substrate, a rear cover body that surrounds the driving means, and the print mechanism. And a front cover body that surrounds the outer periphery of the head cover body and the front cover body connected via a vibration isolating member, while the head substrate and the front cover body are connected via a heat conductive elastic body. Since they are connected, the heat generated by the operation of the printing mechanism is easily transferred between the front cover body and the head substrate of the heat radiation cover via the heat conductive elastic body, and the heat radiation to the outside can be promoted. On the other hand, the vibration of the printing mechanism, etc. is prevented due to the vibration isolating member inserted between the rear cover body and the front cover body and the heat conductive elastic body interposed between the front cover body and the head substrate. It is possible to cut off at each position, and it becomes difficult to transmit to the head substrate, the rear cover body, and the front cover body that form the outer surface of the print head, and it is possible to effectively prevent the generation of noise to the outside.

Further, since the shape of the necessary parts for promoting the heat radiation and reducing the soundproof is small, the structure can be made compact and the cost can be reduced. If the heat conductive elastic body interposed between the front cover body and the head substrate is shaped so as to cover the front surface and the outer peripheral side surface of the head substrate, the noise leakage from the head substrate side is more effective. Can be prevented.

[Brief description of drawings]

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

FIG. 2 is a perspective view of a ring body.

FIG. 3 is a perspective view of a printing unit.

[Explanation of symbols]

 1 Head Main Body 2 Nose Part 3 Printing Unit 4 Heat Dissipation Cover 4a Rear Cover Body 4b Front Cover Body 5 Ring Body 7 Printing Wire 10 Piezoelectric Element 12 Support Frame 24 Thermal Conductive Member 25 Vibration Isolator 26 Thermal Conductive Elastic Body

Claims (2)

[Claims] 1. A plurality of printing mechanisms for driving a printing wire by a driving means are arranged on the rear side of the head substrate, and the printing wire is moved forward from inside a hollow nose portion projecting forward from the head substrate. In the dot impact print head configured as described above, the heat radiation cover to be fitted on the rear side of the head substrate is composed of a rear cover body that surrounds the driving means and a front cover body that surrounds the outer periphery of the printing mechanism, A dot impact print head characterized in that a rear cover body and a front cover body are connected to each other via a vibration isolating member, and a head substrate and a front cover body are connected to each other via a heat conductive elastic body. 2. The dot impact according to claim 1, wherein the heat conductive elastic body connecting the head substrate and the front cover body is formed so as to cover the front surface and the outer peripheral side surface of the head substrate. Print head.