JPH0664189A - Print head - Google Patents

Abstract

PURPOSE:To provide a print head whose lifetime can be prolonged without deteriorating magnetic property and without using lubricating oil. CONSTITUTION:In a spring release type print head, a carbon fiber sheet layer 19 is formed. The carbon fiber sheet layer 19 is made by setting with heat press a single prepreg sheet having carbon fibers arranged in one direction at a part opposing an armature 9 of a core 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head used in a printer.

[0002]

2. Description of the Related Art In a print head, a leaf spring is biased by the magnetic force of a permanent magnet, and the magnetic force of the permanent magnet is canceled by energizing a coil to drive the printing element by releasing the biased leaf spring. There is something I did.

In this type of print head, an armature is provided on a leaf spring, a core is arranged so as to face the armature, and a coil is wound around the core. When the coil is not energized, the armature is attracted to the core by the magnetic force of the permanent magnet and the leaf spring is biased. By this, the biased leaf spring is released.

Among such print heads, there is known one in which a non-magnetic sheet is interposed between the core and the armature for the purpose of improving durability and response speed (for example, Japanese Utility Model Publication No. 57-153543). , Jitsukai Sho 61-152
No. 438). That is, the non-magnetic sheet reduces the attraction force of the armature to the core in the non-energized state, and the biased leaf spring can be quickly released when the coil is energized. Moreover, the core and the armature are not directly collided with each other to prevent the wear of these parts. This non-magnetic sheet is generally formed of a metal such as stainless steel, which is harder than the core or armature, in order to prevent abrasion.

However, since these sheets are made of metal, there is no self-lubricating agent, and it is necessary to supply a lubricating oil such as silicone oil to the abutting portions of the core and armature of the sheet in order to prevent abrasion of the core and armature. In general, an oil impregnated material such as felt impregnated with a lubricating oil such as silicone oil is arranged inside the head. Therefore, there is a problem that the structure becomes complicated, the cost becomes high, and the oil film causes the armature to adhere to the core to cause initial dot omission. Further, there is a problem that the sheet has a short durability life, such that the sheet may be plastically deformed and broken due to long-term use.

Further, since the sheet is made of metal, the impact when the armature is adsorbed by the core cannot be sufficiently absorbed,
This impact has a problem that cracks are likely to occur in the brazed portion of the printing element fixed to the armature or the printing lever.

Further, since these sheets are harder than the core and the armature, wear occurs on the armature,
There was a risk of lowering the printing pressure.

In order to solve the above problems, the present applicant has filed Japanese Patent Application No. 3-344965 "print head". This is one in which a carbon fiber sheet is inserted between the core and the armature, and the carbon fiber sheet itself has a high lubricity, so that the core and armature can be prevented from wearing without supplying lubricating oil. The carbon fiber sheet has sufficient durability.

Further, the carbon fiber sheet has a shock absorbing property and can sufficiently absorb the shock when the armature is adsorbed by the core.

[0010]

[Patent Document 1] Japanese Patent Application No. 3-34
No. 4965 has the following drawbacks.

That is, in the case of a resin prepreg sheet in which carbon fibers are oriented in one direction and cured by hot pressing, one sheet is likely to be broken in the direction parallel to the carbon fibers, and two sheets are also used. When the sheets are laminated such that the stretching directions of the carbon fibers are orthogonal to each other, warpage occurs as a whole sheet due to the difference in shrinkage amount between the two sheets upon cooling after curing by hot pressing.

Therefore, it is necessary to stack three or more sheets, and in order to increase the strength, the carbon fibers are stacked so that the stretching directions thereof are orthogonal to each other, but the overall thickness becomes large, and the magnetic characteristics are increased. Cause a decrease in

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a print head which can prolong its durable life without deteriorating its magnetic properties and without requiring a lubricating oil.

[0014]

In order to achieve the above object, a print head according to the present invention comprises a leaf spring having an armature, a permanent magnet, and a core arranged so as to face the armature and having a coil wound around it. The magnetic force of the permanent magnet biases the leaf spring, and the energization of the coil cancels the magnetic force of the permanent magnet to release the biased leaf spring, thereby driving the printing element through the armature. A printhead having a drive unit,
A carbon fiber sheet layer is formed on a portion of the core facing the armature. The carbon fiber sheet layer is obtained by curing a single prepreg sheet in which carbon fibers are oriented in one direction by hot pressing.

[0015]

According to the present invention, since the carbon fiber sheet layer is formed in the portion of the core facing the armature, the sheet is supported by the core, and the sheet does not break in the direction parallel to the carbon fiber. One layer is enough. Therefore, the gap between the armature and the core can be reduced, and the magnetic characteristics can be improved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A print head to which the present invention is applied will be described with reference to the drawings. As shown in FIG. 1, the print head has
A wire frame 1 is provided at the front end, and a plurality of printing wires 5 as an example of printing elements are axially slidably supported on the wire frame 1 via wire guides 2, 3 and 4.

A leaf spring 6 is provided on the back surface of the wire frame 1, and a donut-shaped permanent magnet 7 and a core 14 are provided behind the leaf spring 6, and a coil 8 is wound around each core 14. . Then, the leaf spring 6 is biased by the magnetic force of the permanent magnet 7, and the magnetic force of the permanent magnet 7 is canceled by energizing the coil 8 to release the biased leaf spring 6 so that the printing wire 5 can be driven. There is.

The leaf spring 6 is connected to the outer peripheral portion in a ring shape, and a plurality of arms 6a extending in a centripetal manner corresponding to the number of the printing wires 5 are formed inside. Each arm 6a
An armature 9 made of a magnetic material is fixed to the front end of the print wire 5, and the rear end of the print wire 5 is fixed by brazing via a print lever 10 fixed to the armature 9. The leaf spring 6 is sandwiched between a stopper plate 11 located on the front surface thereof, a ring-shaped support plate 12 and a yoke plate 13 located on the back surface thereof, and is fixed to the wire frame 1 via screws 15. The stopper plate 11, the leaf spring 6 and the support plate 12 are
In this embodiment, it is made of a non-magnetic material.

The core 14 has a number of U-shaped portions corresponding to the number of the print wires 5, one end of which is joined to the back surface of the yoke plate 13 via the permanent magnet 7, the yoke plate 16 and the spacer 17. The other end faces the armature 9, and the coil 8 is attached to the facing portion via the coil bobbin 18.
Is wrapped around.

Core 14, permanent magnet 7, yoke plate 1
6, the spacer 17, the yoke plate 13, the armature 9, and the coil 8 form an electromagnetic drive device 21.

The permanent magnet 7, the yoke plate 16 and the spacer 17 are all formed of a magnetic material in a ring shape, and the permanent magnet 7, the armature 9, the yoke plate 13 and the core 1 are formed.
4, the yoke plate 16 and the spacer 17 form a loop-shaped magnetic circuit 20. A gap is formed by the yoke plate 16 between the core 14 and the armature 9, and the spacer 17 is used for adjusting the gap between the core 14 and the armature 9.

The operation of the electromagnetic drive device 21 will be described. The permanent magnet 7 attracts the armature 9 to the core 14 against the elastic force of the leaf spring 6 when the coil 8 is not energized so that the leaf spring 6 is fixed. It is designed to be biased. When the coil 8 is energized, the magnetic force of the permanent magnet 7 is canceled to cancel the attraction state of the armature 9 to the core 14, and the leaf spring 6
The biased state is released, and the printing wire 5 is driven by this. That is, when the coil 8 is not energized, the permanent magnet 7
When the coil 8 is energized, the magnetic force of the permanent magnet 7 is canceled and the biased state of the leaf spring 6 is released. Moves forward.

A carbon fiber sheet layer 19 is formed on all of a plurality of facing portions of the core 14 with respect to the armature 9. Due to the presence of the carbon fiber sheet layer 19, the leaf spring 6 in a biased state when the coil 8 is energized. Can be released promptly. That is, the carbon fiber sheet layer 19 reduces the adsorption force of the armature 9 to the core 14 when the coil 8 is not energized, and the adsorption state of the armature 9 is quickly released by energizing the coil 8. ing.

The carbon fiber sheet layer 19 receives the collision force of the core 14 and the armature 9 when the printing wire 5 is returned.

As shown in FIG. 2, the carbon fiber sheet layer 19 is formed of carbon fibers using a thermosetting resin such as epoxy as a binder. As a manufacturing method, the carbon fibers 19a are unidirectional. One piece of the prepreg sheet 19b oriented in the above direction is adhered to the entire surface of the core 14 on the side facing the armature 9, and this is heat-pressed to apply carbon fiber to all of the plurality of facing portions of the core 14 with the armature 9. The sheet 19 is joined and cured. After that, the carbon fiber sheet layer 19 is manufactured by removing a portion other than the facing portion with a press die or the like.

According to the above structure, the carbon fiber sheet layer 1
No. 9 is supported by the core, and since the breakage in the direction parallel to the carbon fiber does not occur, the carbon fiber sheet may have one layer. Therefore, the gap between the armature and the core can be reduced and the magnetic characteristics can be improved.

Further, since the carbon fiber sheet layer 19 itself is made of carbon used as a solid lubricant, the carbon fiber sheet layer 19 has excellent smoothness, and therefore, the wear of the core 14 and the armature 9 is prevented without supplying lubricating oil. it can. This eliminates the need to provide an oil impregnation material such as felt impregnated with a lubricating oil such as silicone oil inside the head unlike the conventional case.
The structure can be simplified and the cost can be reduced. Further, unlike the conventional case, the oil film prevents the armature 9 from closely contacting the core 14 and causing initial dot omission. Further, the carbon fiber sheet layer 19 itself has toughness, and sufficient durability can be obtained.

The binder of the carbon fiber sheet 19 is a thermosetting resin, which is softer than the armature 9 and has a shock absorbing property, and can sufficiently absorb the shock when the armature 9 is adsorbed by the core 14. Therefore, the printing wire 5 caused by the impact when the armature 9 is attracted to the core 14
It is possible to suppress the occurrence of cracks in the brazing part of
The durability of the entire head is improved.

[0029]

As described above, according to the print head of the present invention, the carbon fiber obtained by curing the prepreg sheet in which the carbon fiber is oriented in one direction in the portion of the core facing the armature by hot pressing is used. A sheet layer is formed. The carbon fiber sheet layer is supported by the core, and since the breakage in the direction parallel to the carbon fiber does not occur, the carbon fiber sheet layer may be one layer. Therefore, the gap between the armature and the core can be reduced and the magnetic characteristics can be improved.

Further, because of the carbon fiber sheet, it has an excellent effect that it is possible to provide a high-speed print head having excellent durability at a lower cost without supplying a lubricating oil.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a print head according to the present invention.

FIG. 2 is a sectional view of the main part of the above.

[Explanation of symbols]

 5 printing element 6 leaf spring 7 permanent magnet 8 coil 9 armature 14 core 19 carbon fiber sheet layer 19a carbon fiber 19b prepreg sheet 21 electromagnetic drive device

Claims (1)

[Claims] 1. A leaf spring having an armature, a permanent magnet, and a core around which a coil is wound and which is arranged so as to face the armature, and the leaf spring is biased by the magnetic force of the permanent magnet. A print head having an electromagnetic drive device for driving a print element via the armature by canceling the magnetic force of the permanent magnet by energizing the coil to release the leaf spring in a biased state, A printhead, wherein a carbon fiber sheet layer is formed by heat-pressing a single prepreg sheet in which carbon fibers are oriented in one direction, on the portion of the core facing the armature.