JP3066683B2 - Release 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 release type print head used in a printer.

[0002]

2. Description of the Related Art FIG. 3 is a view for explaining the structure of a conventional release type print head (FIG. 3 (A) is a front view, FIG. 3 (B) is a side view, FIG.
(C) is a sectional view, wherein 1 is a core, 2 is a coil wound around the core 1, 3 is a permanent magnet disposed in a magnetic path including the core 1, and 4 is facing the core 1 Reference numeral 5 denotes a cantilever plate spring that supports the armature 4. In addition,
A plurality of sets of the core 1, the coil 2, the permanent magnet 3, the armature 4, and the leaf spring 5 are provided in the circumferential direction.

The coil 2 receives a current at a predetermined time via a printed board 7 attached to a housing 6, and the printed board 7 has a connector 8 for connection to a power supply. Installed. A beam 9 is connected to the armature 4, and a wire 10 is fixed to a tip of the beam 9. The wire 10 moves while being guided by a nose portion 11 integrated with the housing 6. The print head having such a configuration is mounted on a carrier that advances and retreats along the platen, and operates at a predetermined time to perform printing. The operation is as follows.

During non-printing, the coil 2 is not energized, the armature 4 is attracted to the core 1 by the attraction generated by the magnetic flux formed through the magnetic path by the permanent magnet 3, and energy is accumulated in the leaf spring 5. ing. At the time of printing, the coil 2 wound around the predetermined core 1 is energized for a predetermined time at a predetermined time. As a result, a part of the magnetic flux generated by the permanent magnet 3 is canceled by the magnetic flux generated by the coil 2 and the armature 4
Is released, and is urged by the leaf spring 5 to rotate in the printing direction.

By the rotation of the armature 4, the wire 10 projects to the left in FIG. 3 (C), and strikes a platen via the ink ribbon and the recording paper to form (print) dots on the recording paper. At the time of completion of the printing, the power supply to the coil 2 is stopped, and the armature 4 is attracted to the core 1.

In a conventional release type print head having such a configuration and operation, a leakage plate 12 made of a magnetic material for leaking magnetic flux is attached to the head outer periphery 15. This leak plate 12 is used for adjusting the armature suction force. FIG. 4 shows details of a portion where the leakage plate 12 is attached, where 13 is a yoke and 14 is a magnet base.

[0007]

The above-mentioned conventional print head has a problem that when the temperature of the print head rises, the magnetic flux density decreases due to the characteristics of the permanent magnet, and the armature cannot be attracted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a release type print head which can prevent a decrease in armature suction force when the temperature of the head is raised.

[0009]

In order to achieve the above object, according to the present invention, there is provided a permanent magnet for forming a magnetic flux passing through a core and an armature, and a leakage plate made of a magnetic material for leaking magnetic flux is attached to the outer periphery of the head. In the release print head, a recess is provided at a position facing the permanent magnet inside the leakage plate.
Is formed, and the thermal expansion in contact with the outer periphery of the head is formed in the concave portion.
The change in thickness due to the configuration, characterized in that interposed thermal expansion member used as a displacement amount.

[0010]

[0011]

When the temperature of the print head rises, the thermal expansion member expands, and the leakage plate of the magnetic material that leaks magnetic flux separates from the outer periphery of the head. Therefore, the magnetic flux leakage effect of the leakage plate is reduced,
The problem that the armature is not sucked is solved.

[0012]

[0013]

First, the premise of the present invention will be described with reference to FIG.
A reference example will be described. FIG. 1 is an explanatory diagram of a main part structure of a release type print head according to a reference example which is a premise of the present invention (FIG. 1 (A) shows a temperature rising state, and FIG. 1 (B) shows a normal temperature state). In the figure, 21
Is a thermal expansion member such as silicon rubber. The same reference numerals are used for members similar to those in the related art. Further, other members (not shown) of the print head are the same as in the related art. The thermal expansion member 21 is disposed between the outer periphery 15 of the head and the leakage plate 12.

The printing operation by the print head having such a main part structure is performed in the same manner as in the prior art.
The thermal expansion member 21 is as shown in FIG.
Part of the magnetic flux leaks through the leak plate 12.

When the temperature of the print head rises due to printing for a long time or the like, the conventional structure has a problem that the magnetic flux density is reduced due to the characteristics of the magnet, and the armature cannot be attracted. However, in this example, the thermal expansion member 21 is interposed between the head outer periphery 15 and the leakage plate 12, and the thermal expansion member 21
1A, the leakage plate 12 is separated from the head outer periphery 15 as shown in FIG. 1A, and the magnetic flux leakage effect of the leakage plate 12 is reduced.

More specifically, the thermal expansion member has a thickness of 1 m.
When silicon rubber of m is used, when the temperature is raised to 100 ° C., it expands by 0.05 mm in the thickness direction, thereby reducing magnetic flux leakage by about several percent. Therefore, the conventional problem that the armature cannot be sucked is solved.

[0018]

FIG. 2 shows an embodiment of the present invention .

FIG. 2 is an explanatory view of a main part structure of a release type print head according to an embodiment of the present invention . FIG.
((B) shows the state at normal temperature), in which 31 is a thermal expansion member. A ring-shaped recess 32 is formed inside the leakage plate 12 at a position facing the permanent magnet 3, and the thermal expansion member 31 is disposed in the recess 32.

In the case of this embodiment, since the thermal expansion member 31 is provided in the recess 32 of the leakage plate 12 at a position facing the permanent magnet 3, the leakage plate 12 In the vicinity of the head outer periphery 15. Therefore, the magnetic flux leakage effect can be more reliably reduced.

[0021]

As described above, according to the present invention, the armature can be sucked even when the temperature of the print head rises, and the stable print quality can be maintained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part structure of a release type print head according to a reference example which is a premise of the present invention, and FIG.
FIG. 1B shows the state at normal temperature.

[2] In main structure diagram of a real施例release type print head of the present invention, FIG. 2 (A) shows a during heating ,, Figure 2 (B)
Indicates a normal temperature.

FIG. 3 is a structural explanatory view of a conventional release type print head.
3A is a front view, FIG. 3B is a side view, and FIG. 3C is a cross-sectional view.

FIG. 4 is an enlarged view of a main part of FIG. 3 (C).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core 2 Coil 3 Permanent magnet 4 Armature 12 Leak plate 15 Head outer periphery 21, 31 Thermal expansion member 32 Depression

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akinori Murata 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Mitsuhiro Mori 1405 Daimaru Daimaru, Inagi City, Tokyo Inside Fujitsu Isotec Co., Ltd. 56) References JP-A-63-290757 (JP, A) JP-A-64-64863 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/28

Claims (1)

(57) [Claims] 1. A release print head comprising a permanent magnet (3) for forming a magnetic flux passing through a core and an armature, and a leakage plate (12) of a magnetic material for leaking a magnetic flux attached to an outer periphery (15) of the head. Facing the permanent magnet (3) inside the leakage plate (12)
A recess (32) is formed at the position, and the recess is formed in the recess (32).
Change in thickness due to thermal expansion in contact with the outer circumference (15) of the head
A release type print head characterized by interposing a thermal expansion member (31) used as a displacement amount .