JPH044157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a wire dot head, and more particularly to a wire dot head equipped with a mechanism for efficiently dissipating heat generated from an electromagnet that is housed in the head body and that attracts and operates a wire-driving armature. Regarding the head.

Prior Art When one character is composed of dot matrices, if m×n dot matrices are arranged as shown in Fig. 1, then n dot matrices are arranged at a pitch of P ₂ in the vertical direction. If you use a print head with wires lined up in a row, shift this print head to the right or left m times at a pitch of P ₁ , and drive the wire for each pitch, m x
n dot matrices can be constructed.

In general, a wire dot head uses an electromagnet housed in the head body to attract and operate an armature, and this armature drives a wire into pressure contact with the print paper via an ink ribbon to perform desired printing using the aforementioned dot matrix. There is. During this armature suction operation, heat is generated by the excitation of the coil of the electromagnet, so that the head body generates heat. Therefore, as the coil resistance increases due to this heat generation, the excitation current decreases, and the force that electromagnetically attracts the armature decreases. For this reason, the pressure driving force of the wire connected to the armature, that is, the printing pressure, decreases, resulting in a decrease in printing quality. Additionally, the surface temperature of the head rises to about 90°C, which is extremely dangerous for the operator.

Purpose The present invention has been made in view of the above points, and provides a wire dot head that suppresses the rise in surface temperature of the wire dot head, increases the efficiency of converting electrical energy into printing energy, and improves operational safety. The purpose is to provide.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings.

In the embodiment described below, the yoke of the armature driving electromagnet and the back holder that functions as an external heat dissipation member are in surface contact with each other, and the flexible cable that functions as a current supply member to the electromagnet and the yoke also serve as a spacer for heat conduction. It is characterized by the provision of a heat dissipation plate made of highly durable aluminum.

FIG. 2 is a longitudinal sectional view of one embodiment of the wire dot head according to the present invention, and FIG. 3 is an exploded perspective view of the main parts thereof. In these drawings, 1
2 is a tip guide for facilitating the assembly of the wire 22 into the head body, and 2 is an intermediate guide that is attached to a bag holder (to be described later) with a screw 23 or the like via a fitting portion for positioning (not shown).
This intermediate guide 2 is provided with a groove 2a for a screw to be attached to a carriage (not shown), and is U-shaped for easy attachment and detachment of the head. 3 is a flexible cable for supplying current to the coil of the electromagnet, which will be described later; 4 is a heat dissipating cable that is in surface contact with the yoke of the electromagnet and the back holder, which will be described later, according to the present invention, and also serves as a spacer between the flexible cable 3 and the yoke. It is a plate. In the example, the thickness of the plate is approximately 2 mm to enable sufficient conduction of heat from the yoke to the bag holder, and the material is preferably aluminum or magnesium, which has good thermal conductivity, and aluminum is used in the example. has been done. Reference numeral 5 designates the yoke of the electromagnet, which is formed into an elliptical shape as shown in FIG. 4, and is configured to equalize the sliding resistance of the wire and prevent density unevenness between each dot formed on the printing paper. It is becoming. A core 6 is connected to the yoke 5, and a bobbin 8 on which a coil 7 is wound is fitted onto the core 6. This bobbin 8 is provided with two terminals 8a, and the winding start and winding end portions of the coil 7 are soldered.These two terminals are also soldered to the aforementioned flexible cable 3, and the coil 7 is connected to the coil 7 by soldering. energization is performed. Reference numeral 9 denotes a rear guide located at the center of the head body and housed in the yoke 5. One end of a restoring spring 10 for returning the armature to its initial position after driving is fixed to this rear guide 9. 14 is attracted and the wire 22 prints dots, and then the restoring spring 10 and the stopper 15 restore the dots to their initial state. This restoring spring 10 and stopper 1
5 are aligned so that the movement of the armature 14 is stable. That is, the strength of the restoring spring 10 and the hardness of the stopper 15 are determined to enable stable movement of the armature 14, and in the embodiment, polyurethane or the like is used as the material of the stopper 15.

Reference numeral 11 denotes an auxiliary yoke arranged in parallel with the yoke 5, and 12 is an auxiliary yoke that is designed to prevent wear due to rotation due to line contact with the auxiliary yoke 11, residual magnetism of the auxiliary yoke 11, etc., which may be a problem when forming a closed magnetic path. A spacer such as a polyester film is interposed between the auxiliary yoke 11 and the armature 14 in order to prevent the movement of the armature 14 from becoming unstable. A plunger 13 is fixed to the armature 14, and a wire 22 is connected to the tip of the armature 14 by brazing. Further, the other end of the armature 14 is provided with a hole (not shown) into which the aforementioned fitting portion of the bobbin 8 is fitted, and the armature 14 rotates about this fitting portion as a fulcrum. Reference numeral 16 denotes an armature holder, which stabilizes the rotation of the armature 14 by pressing and holding the pivot portion from the rear when the armature 14 rotates. Also, this armature holder 1
6 is fitted with the stopper 15 described above.
A leaf spring 17 is provided in contact with the armature holder 16, and the elastic displacement of the leaf spring 17 uniformly presses the armature holder 16. These auxiliary yoke 11, armature 1
4. The arrangement relationship between the armature holder 16 and the leaf spring 17 is shown in FIG. 18 is a damper provided on the leaf spring 17, and this damper 18 is held in pressure contact with a back holder 21 which functions as an external heat radiating member via a washer 19 and a spring washer 20. The shape of the back holder 21 has a large effect on the heat dissipation of the wire dot head, so it is preferable that the surface area be as large as possible. This damper 18 is configured to be swingable by a leaf spring 17 and a spring washer 20, thereby further enhancing the vibration-proofing effect. The washer 19 also prevents the spring washer 20 from biting into the damper 18. In addition, the wire 22 is supported by each guide 1, 2, and 9 for ease of assembly, reducing the drag force from each guide.
The structure is such that the sliding resistance of No. 2 is reduced and the printing energy conversion efficiency of electrical energy is improved.

When the coil 7 of the head configured as described above is energized via the flexible cable 3, a closed magnetic path is formed by the yoke 5, the auxiliary yoke 11, the plunger 13, and the core 6, so the plunger 13 is attracted to the core 6, and as a result, the armature 14 The connected wire 22 is pushed out, and a dot is formed on the printing paper via an ink ribbon (not shown).
However, as mentioned above, the coil 7 generates heat due to the resistance of the coil 7 itself and the generation of eddy current in the core 6.
The attraction force decreases due to a decrease in excitation current due to an increase in its own resistance, leading to a decrease in printing quality.
In this case, the heat-resistant temperature of the coating of the coil 7 is approximately 120°C according to experiments, and the heat-resistant temperature of the bobbin 8 is approximately 150°C, so the heat generation temperature of the solenoid section is 120°C.
Must be as follows. For this purpose, a mechanism must be used that increases the conversion efficiency of electrical energy into printing power and enhances the heat dissipation of the generated heat. As a countermeasure for the former, a mechanism that increases the magnetic efficiency of the magnetic path and also minimizes the sliding resistance of the wire 22 may be used. In this embodiment, the latter mechanism for enhancing heat dissipation is particularly improved.

According to this embodiment, as can be understood from the radiation path of heat from the electromagnet in FIG. Since the yoke 5, which is in this state of generating heat and is collected from the solenoid section, is in close contact with the heat sink plate 4, the heat is efficiently conducted to the heat sink plate 4. The heat conducted to the heat radiating plate 4 in this manner is conducted to the bag holder 21 through the contact portion with the bag holder 21, which functions as an external heat radiating member.

According to one embodiment of the present invention, the heat generated from the coil 7 and the core 6 is efficiently radiated through the back holder 21, so that a decrease in printing power does not occur and high print quality is maintained even when printing for a long time. can. This heat dissipation mechanism also allows the temperature of the wire dot head to drop by approximately 20°C, allowing safe printer operation.

Effects As described above, the present invention can suppress the rise in the surface temperature of the wire dot head, increase the conversion efficiency of electrical energy into printing energy, and improve operational safety.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the configuration of a dot matrix, FIG. 2 is a longitudinal sectional view showing an embodiment of the wire dot head according to the present invention, and FIG. 3 is a main part of the wire dot head shown in FIG. FIG. 4 is a view taken along the line A-A' in FIG. 2, FIG. 5 is a view taken along line B-B' in FIG. 2, and FIG. 6 is an exploded perspective view of the embodiment shown in FIG. FIG. 3 is a partial cross-sectional view for explaining conduction of heat generation from an electromagnet in FIG. 4... Heat dissipation plate, 5... Yoke, 6... Core, 7... Coil, 13... Plunger, 14...
... Armature, 21... Back holder, 22...
…wire.

Claims (1)

[Scope of Claims] 1. A wire dot head that performs desired printing using a plurality of wires that are driven into pressure contact with a printing target in response to a plurality of armatures that are attracted and operated by electromagnets housed in the head main body, comprising: A heat radiating plate is provided which is in surface contact with the yoke of the electromagnet and is also provided in surface contact with and opposite to the external heat radiating member of the head body, and which is arranged in parallel as a spacer between the current supply member to the electromagnet and the yoke. A wire dot head characterized by: 2. The heat dissipation plate and the external heat dissipation member are
The wire dot head according to claim 1, characterized in that it is made of a material with good thermal conductivity, such as aluminum or magnesium.