JP2743231B2 - Print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head for an impact printer.

2. Description of the Related Art Impact printers have been widely used mainly in business courses because of their low running costs, but they have the disadvantage of high printing noise. Therefore, in order to further expand the use of this type of printer device, it is necessary to realize low noise. By realizing this, it is expected that demand for personal use will be generated.

[0003]

2. Description of the Related Art FIG. 7 is a side view showing the structure of a conventional piezoelectric print head. In the figure, reference numeral 1 denotes a nose, 2 denotes a heat sink which is an envelope, and a piezoelectric actuator assembly 3 is mounted in the heat sink 2. Although not shown, the piezoelectric print head is mounted on a carrier movable along a platen, and operates while moving with the carrier to perform printing. Configuration of the piezoelectric actuator assembly 3,
The operation is as follows.

The piezoelectric actuator assembly 3 has a plurality of laminated piezoelectric elements 5 mounted on a common base 4 at a predetermined pitch in the circumferential direction, and an armature 6 and an enlarging mechanism 7 corresponding to each piezoelectric element 5. Are provided. The piezoelectric element 5 is attached by fixing the base side block 8 fixed to the lower part to the base 4 with an adhesive or the like.

[0005] The armature 6 is formed by integrally connecting a beam 10 having a wire 9 fixed to the tip to a base 11. The enlargement mechanism 7 includes a support spring 12 and a movable spring 13 which are arranged substantially in parallel. The support spring 12 has both ends fixed to the base 11 and the base 4, and the movable spring 13 has both ends fixed to the base 11 and the block 14 (separate from the base 4).

Further, a casting material 18 is cast and filled in the heat sink 2, and the portion of the piezoelectric actuator assembly 3 excluding the armature 6 and the enlargement mechanism 7 is covered with the casting material 18. The casting material 18 is a sound-proof and vibration-proof material, and is excellent in absorbing the impact force. The print head of FIG. 5 filled with the casting material 18 is disclosed in Japanese Patent Application No. 2-175509 (filed on Jul. 2, 1990) already proposed by the present applicant.

The silicone gel used for the casting material 18 is a silicone agar obtained by curing a liquid silicone oil by a hydrosilation (addition) reaction at a crosslink density of 1/5 to 1/10 that of a conventional silicone elastomer. Is a low-viscosity liquid before curing,
After being cured, it becomes a purine-like, highly tacky gel-like elastomer, and is a functional material having both the characteristic properties of organopolysiloxane and the properties resulting from the low crosslink density.

The basic structure is obtained by cross-linking an organopolysiloxane having vinyl groups at both terminals and side chains with polyhydrodiene siloxane. The viscoelastic properties (elastic modulus and loss coefficient) can be obtained by changing the cross-link density and molecular weight. Can be adjusted. For example, when the polymer molecular weight is increased and the crosslink density is decreased, a gel having a large loss coefficient in a low frequency region can be obtained, and the gel has excellent vibration proof and shock absorbing performance.

[0009] Accordingly, by filling this as a vibration-proof material as shown in FIG. 7, the vibration-proof and sound-proof effect can be improved with respect to a wide range of vibration frequencies near the piezoelectric actuator assembly 3. As the casting material 18, an ω type manufactured by Siegel Co., Ltd. is optimal, and has excellent impact force absorption. In addition, any of the α type, β type and γ type manufactured by the company can be used.

At the time of printing, a voltage is applied to a predetermined piezoelectric element 5 via a connector 15. As a result, the piezoelectric element 5 is displaced upward, and pushes up the movable spring 13. Then, the armature 6 rotates in the direction of the arrow A by the action of the magnifying mechanism 7, and the magnified displacement is transmitted to the wire 9. As a result, the wire 9 moves by a predetermined amount in the direction of arrow B, and printing is performed. The movement of the wire 9 is guided to the nose 1.

When printing is completed, the application of voltage to the piezoelectric element 5 is cut off, so that the wire 9 on which printing has been completed is connected to the armature 6, the supporting spring 12, the movable spring 13, and the piezoelectric element 5.
It returns to its original state. Each connector 15
Are connected to a common connector 17 via a printed board 16, and power is supplied to the piezoelectric element 5 via the connector 17.

[0012]

In the above-described conventional print head, a casting material such as a gel-like silicone material is cast and filled for the purpose of noise reduction. However, the weight of the print head increases. However, the lateral vibration of the printer during printing increases, which hinders a high-speed printing. Further, since the noise is increased by the vibration of the housing, a sufficient effect cannot be expected with the conventional technology.

An object of the present invention is to provide a print head capable of achieving high speed and low noise.

[0014]

In order to achieve the above object, according to the present invention, there are provided a plurality of piezoelectric elements, a plurality of armatures provided corresponding to the respective piezoelectric elements and having a wire at a tip, and a plurality of the piezoelectric elements. A piezoelectric actuator assembly provided between the element and each of the armatures, and including a plurality of enlargement mechanisms for enlarging the displacement of the piezoelectric element when voltage is applied and transmitting the displacement to the wire to perform printing. Wherein the piezoelectric actuator assembly excluding the armature and the enlarging mechanism is provided with a cavity in the casting material in a print head covered with the casting material (first configuration). And

Further, a second aspect of the present invention is characterized in that a foamable sound absorbing material filled in a cavity is added to the print head of the first configuration.

[0016] Further, a plurality of armatures provided with wires and a plurality of electromagnet mechanism portions for driving the respective armatures to perform a printing operation on the wires are provided, and each of the electromagnet mechanism portions is covered with a casting material. The print head has a configuration (third configuration) in which a cavity is provided in the casting material.

Further, a foaming sound absorbing material filled in the cavity is added to the print head of the third structure (fourth structure).

[0018]

In the first and third configurations, the vibration (noise) generated when the print head is driven is attenuated by the casting material, and is further absorbed by the air layer in the cavity, so that the noise attenuating effect is improved. Further, the weight is reduced by the amount of the hollow portion, and the lateral movement of the head is reduced by increasing the margin of the space operation condition at the time of printing, so that the noise does not increase due to the vibration of the housing.

In the case of the second and fourth configurations, the noise attenuation effect is further improved by the sound absorbing effect of the foamable sound absorbing material in the cavity.

[0020]

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

FIGS. 1 to 3 show a first embodiment.

FIG. 2 is a perspective view showing the appearance of a printer using a piezoelectric print head. In FIG. 2, reference numeral 21 denotes a piezoelectric print head, 22 denotes a platen, and 23 denotes a guide. The piezoelectric print head 21 is mounted on a carrier which is guided by a guide 23 and is movable along a platen 22, and moves along with the carrier to perform printing. The appearance of the piezoelectric print head is as shown in FIG. 3, and the same members as those in the related art are denoted by the same reference numerals.

FIG. 1 is a side view showing the structure of the piezoelectric print head 21.
The casting material 18 is filled so as to surround the piezoelectric actuator assembly 3 excluding the enlargement mechanism 7. A cavity 24 is provided at the center of the casting material 18.

The vibration generated when the print head having such a configuration is driven is attenuated by the casting material 18 and further absorbed by the air layer in the cavity 24, so that the noise attenuation effect is improved. Further, the weight is reduced by the amount of the hollow portion 24, which leads to an increase in the margin of the space operation condition at the time of printing, and reduces the head side-to-side vibration. Therefore, the noise is not increased by the vibration of the housing.

FIG. 4 shows a second embodiment.

The piezoelectric print head 31 of the present embodiment has
It is the same as the previous example except that the inside is filled with a foamable sound absorbing material 32.

In the case of this example, the sound absorbing material 32 in the hollow portion 24
, The noise reduction effect is further improved.

In the above description of each embodiment, an example in which a piezoelectric element is used as an actuator has been described. However, the present invention is also applicable to a print head in which an armature having a wire is driven by a well-known electromagnet mechanism. is there. As the electromagnet mechanism, any of an adsorption type and a release type may be used, and the casting material is filled except for the amateur which is a movable portion. 5 and 6 show specific examples as third and fourth embodiments.

FIG. 5 shows a third embodiment, and shows the structure of a print head 41 provided with a release type electromagnet mechanism.
The print head 41 arranges a plurality of electromagnet mechanisms 42 at a predetermined pitch in the circumferential direction, and
2 is provided with an actuator assembly 44 provided with an armature 43 corresponding to 2. 45 is a printed board. The electromagnet mechanism 42 includes a core 47 on which a coil 46 is wound, and a base 48 for fixing a base of the core 47.
, A permanent magnet 49 and a leaf spring 50 in the arrangement shown.

The amateur 43 includes a base 51 and the base 5.
The base 52 is opposed to the core 47. The base 52 is composed of a beam 52 connected to the beam 1 and a wire 53 fixed to the tip of the beam 52. Printing by the print head 41 having such a configuration is performed as follows.

During non-printing, the coil 46 is not energized, and the armature base 51 is attracted to the core 47 against the urging force of the leaf spring 50 by the attraction force of the magnetic flux formed by the permanent magnet. When printing, coil 4
6 is energized through the connector 54 and the printed board 45 for a predetermined time. As a result, a part of the magnetic flux generated by the permanent magnet 49 is canceled by the reverse magnetic flux generated by energizing the coil, the armature 43 is released from the attraction, and the plate spring 5 is released.
The wire 53 is rotated in the direction of arrow C by the urging force of 0 to cause the wire 53 to perform a printing operation.

At the time of completion of the printing, the power supply to the coil 46 is stopped, and the armature 43 having completed the printing is attracted to the core 47 again.

In the print head 41, the electromagnet mechanism 42 is covered with a casting material 55, and a cavity 56 is formed at the center of the casting material 55. Therefore, the same effects as in the first embodiment can be obtained.

FIG. 6 shows a fourth embodiment, in which the same reference numerals are used for members similar to those in the third embodiment. In this print head 61, the cavity 56 is filled with a foamable sound absorbing material 62 similar to that of the second embodiment. Therefore, the same effect as in the second embodiment can be obtained.

[0035]

As described above, according to the present invention, the noise generated when the print head is driven is attenuated by the casting material, and is further absorbed by the air layer in the cavity, so that the noise attenuating effect is improved. Furthermore, the weight is reduced by the amount of the cavity,
Since the lateral vibration of the head is reduced by leading to an increase in the margin of the space operation condition at the time of printing, the noise does not increase due to the vibration of the housing.

When the foamed sound absorbing material is filled in the cavity, the noise attenuation effect is further improved by the sound absorbing effect of the sound absorbing material.

[Brief description of the drawings]

FIG. 1 is a side view showing a structure of a piezoelectric print head according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of a printer using the piezoelectric print head according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing the appearance of the piezoelectric print head according to the first embodiment of the present invention.

FIG. 4 is a side view showing a structure of a piezoelectric print head according to a second embodiment of the present invention.

FIG. 5 is a side view showing the structure of a print head according to a third embodiment of the present invention.

FIG. 6 is a side view illustrating a structure of a print head according to a fourth embodiment of the present invention.

FIG. 7 is a side view showing a configuration of a conventional piezoelectric print head.

[Explanation of symbols]

 Reference Signs List 2 heat sink 3 piezoelectric actuator assembly 5 piezoelectric element 6,43 amateur 7 magnifying mechanism 9,53 wire 18,55 casting material 21,31 piezoelectric printing head 24,56 cavity 32,62 foaming sound absorbing material 41,61 printing Head 42 Electromagnet mechanism

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-281858 (JP, A) JP-A-2-212154 (JP, A) JP-A-4-39058 (JP, A) JP-A-4- 201374 (JP, A) JP-A-4-241959 (JP, A) JP-A-5-77450 (JP, A)

Claims (4)

(57) [Claims] 1. A plurality of piezoelectric elements (5), a plurality of armatures (6) provided corresponding to the piezoelectric elements (5) and having a wire (9) fixed at a tip thereof; and the piezoelectric element (5). And an enlarging mechanism (7) provided between the armature (6) and the armature (6) for enlarging the displacement of the piezoelectric element (5) when voltage is applied and transmitting the displacement to the wire (9) for printing. A print head comprising a piezoelectric actuator assembly (3) comprising the above-described piezoelectric actuator assembly (3), excluding the armature (6) and the enlarging mechanism (7), covered with a casting material (18). A print head, wherein a cavity (24) is provided in the casting material (18). 2. A print head according to claim 1, further comprising a foamable sound absorbing material (32) filled in the cavity (24). 3. A plurality of armatures (43) having wires (53), and a plurality of electromagnet mechanisms (42) for driving the respective armatures (43) to cause the wires (53) to perform a printing operation. A print head, wherein each of the electromagnet mechanisms (42) is covered with a casting material (55), wherein a cavity (56) is provided in the casting material (55). 4. A print head according to claim 3, wherein a foamable sound absorbing material (62) filled in the cavity is added to the print head.