JPS61233575A - Apparatus for dissipating heat of printing head - Google Patents

Abstract

PURPOSE:To efficiently dissipate heat by rapidly transferring the heat generated in a printing head from a main body to the outside, by inserting a part of a heat pipe in the hole formed to a yoke in a closely contacted and engaged state. CONSTITUTION:A hole is formed to a yoke 2 and a part of a heat pipe 7 is inserted in said hole in a closely contacted and engaged state. The printing by a printing hammer 6 is performed by continuously or intermittently performing the instantaneous supply of a current to the coil 3a of an electromagnet mechanism 3. The heat generated in the coil 3a and the yoke 2 conducts through the yoke 2 to reach the surface of the heat pipe 7 and absorbed as the latent heat of evaporation of the sealed liquid of the heat pipe 7 to be rapidly transferred to the part, protruded to the outside of a printing head, of the heat pipe 7 and diffused to the open air from said part.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a heat dissipation device for a dot printer using a heat pipe.

Conventional technology Impact-type dot printers have been widely used as computer terminal devices, but in particular, with the recent spread of word processors, there is a demand for printers with a large number of dot matrix dots and high-speed printing performance. It is now possible to do so. As a result, the print head of dot printers has been designed to be highly densely packaged, while also being required to withstand extremely severe continuous high-speed printing. Various types of devices have been devised since then, and are actually implemented and widely used, but the most basic structure of these devices is
The structure is as shown in the figure, and the actual situation is that this basic structure is slightly modified or various ideas are added. In the same figure, 101 is a plate spring/impact arm, and its peripheral portion 101a is connected to the housing 102.
, and a printing hammer 10 is attached to the tip near the center.
3 is fixed.

An armature 104 is attached to the middle of the span of the leaf spring/impact arm 101, and an electromagnetic mechanism tOS is disposed opposite to the armature 104.
, the yoke 106, the permanent magnet 107, the leaf spring/impact arm 101, and the armature 104. A closed circuit constitutes a magnetic path for the magnetic flux of the permanent magnet. In the print head, such structures are closely arranged radially, and in the non-printing state, each leaf spring/impact arm 101
The armature 104 is attracted to the electromagnet mechanism 105 by the magnetic flux of the permanent magnet 107, and in the printing state, the coil 105a of the electromagnet mechanism is energized and the permanent magnet 107
A reverse excitation flux is instantaneously generated to cancel the magnetic flux of the permanent magnet 107 to release the armature 104 from the electromagnetic mechanism 105, and the printing hammer 103 is activated by the elastic energy stored in each leaf spring/impact arm lO1. Printing is performed by driving toward a platen (not shown). Incidentally, since the current is no longer supplied after printing, the armature 104 is activated again by the electromagnetic mechanism l.

5, it will be restored to its original state and wait for the next energization. By the way, in this driving state of the print head, heat is generated due to copper loss caused by the current flowing through the coil 105a of the electromagnet mechanism, iron loss caused by a sudden change in magnetic flux passing through the core of the electromagnet mechanism, etc. However, there is a problem in that the configuration of the print head limits high-density packaging and makes it impossible to perform continuous high-speed printing. To solve this problem, a conventional method that has been used is to attach a heat dissipation plate 108 to the back of the print head, as shown in FIG. 6, to dissipate the generated heat as efficiently as possible. (Refer to JP-A-59-202863, JP-A-59-207266, etc.), or automatically lowers the printing speed when continuous printing conditions become severe to prevent print head abnormalities due to heat accumulation. This is to prevent high temperatures. In addition, since heat accumulates mainly in the center of the print head,
Various problems can occur due to the expansion difference caused by the temperature difference between the center and the periphery, and measures have been taken to minimize this effect by selecting materials. (Refer to Japanese Patent Application Laid-Open No. 59-202861).

Problems to be Solved by the Invention However, installing a heat dissipation plate considerably increases the mass of the entire print head, which impedes the high-speed transport drive of the print head itself, resulting in a hindrance to high-speed printing. It goes without saying that lowering the printing speed goes against the original purpose.Also, it is necessary to select materials that take WM elongation into consideration, which is ideal due to the relationship with magnetic permeability. Therefore, in this invention, the heat generated in the print head is quickly transferred from the main body to the outside by utilizing the high heat transfer property of the heat pipe. An object of the present invention is to provide a heat dissipation device for a print head that solves the above problems by efficiently dissipating heat externally.

Means for Solving the Problems The printhead heat dissipation device of the present invention includes a permanent magnet, a yoke, a core of an electromagnetic mechanism, and a spring-supported armature to form a magnetic path of the permanent magnet, and a coil of the electromagnetic mechanism. In the print head, the heat pipe is inserted into the hole formed in the yoke in the print head, in which the magnetic flux caused by the permanent magnet is energized, the armature is released by the spring elasticity, and a predetermined printing operation is performed using the print hammer provided on the armature. It is characterized by the fact that the parts are tightly fitted. In general, a "heat pipe" is a metal pipe whose ends are sealed, the inside of the pipe is lined with a porous material called wick, and the inside of the pipe is once vacuumed. It contains a small amount of liquid, enough to completely wet the wick afterwards. Then, when one end of the pipe is heated to warm the liquid seeping into the wick, the inside of the heat pipe is at saturated vapor pressure, so this warmed liquid evaporates directly, causing a large amount of evaporation. It carries latent heat and quickly moves to each part of the pipe. Heat pipes thus rapidly transfer large amounts of heat from one place to another.

Figure 1 shows the basic concept of this invention, l is a permanent magnet,
2 is a yoke, 3 is an electromagnetic mechanism, 4 is a leaf spring, and 5 is an armature, which form a mechanical and electrical mechanism for driving the printing hammer 6.

A feature of the present invention is that a hole is formed in the yoke 2, and a portion of the heat pipe 7 is tightly fitted into the hole.

Printing with the action printing hammer 6 is performed by continuously or intermittently energizing the coil 3a of the electromagnetic mechanism, but the heat generated in the coil 3a and the yoke 2 is transferred from the surroundings of the print head to the air. However, when continuous printing continues under severe conditions, the heat dissipation is not sufficient and the heat remains in the print head. This heat is conducted through the inside of the yoke 2 and reaches the surface of the heat pipe 7, where it is absorbed as latent heat of vaporization of the liquid sealed in the heat pipe 7, and is immediately transferred to the portion of the heat pipe 7 that protrudes to the outside of the print head. from the same location and dissipates into the air. By using the heat pipe 7 in this way, the heat generated in the print head is transferred to the outside extremely quickly, and the entire surface of the portion of the heat pipe 7 that protrudes from the print head is exposed to the outside air, which increases efficiency. Dissipates heat well. In particular, due to the mechanical structure of the print head, the packaging density is extremely high, and as a result, the heat accumulated inside is difficult to dissipate to the outside, and the temperature inside the center rises abnormally. Being able to transport it is convenient.

Furthermore, since the heat pipe 7 can rapidly transfer a large amount of heat corresponding to the latent heat of vaporization, it is effective against the generation of shock heat, and it is possible to keep the temperature of the print head constant at all times.

Embodiment Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2 to 5.

In the first embodiment, as shown in FIG. 1, a part of the yoke 2 of the print head is configured as a tubular part 2a in the center of the print head, and an open tube + IA wire 911/Fl Hachiyama I
ψ Ray L, -No 7^- 剋 is also a heat dissipation device for the print head inserted into the T leg.

If the tubular part 2a of the yoke 2 is formed in the center of the print head and the heat is transferred from there by the heat pipe 7, the contact area between the heat pipe 7 and the yoke 2 becomes large, and Since the amount of heat generated tends to stay in the center of the print head, the heat can be efficiently removed by the heat pipe.

In the second embodiment, as shown in FIG. 2, the heat pipe 8 is bent in the middle, and the bent part or end part 8b is vertical with respect to the part 8a of the heat pipe 8 that is tightly fitted into the yoke 2. A part of the heat pipe 8 is tightly fitted so as to be positioned on the upper side in the direction.

The reason why the heat pipe 8 is used in this way is to enable the sealed liquid within the heat pipe 8 to repeat the vaporization and liquefaction process smoothly, thereby making it possible to improve the heat transfer efficiency of the heat pipe 8 itself. .

The third example is a method in which a paste-like thermal conductor is interposed on the contact surface between the heat pipe and the yoke, and this paste-like thermal conductor is often used between semiconductor element heat sinkers. The ones listed below are the best.

The purpose of interposing the paste-like thermal conductor in this way is to improve the heat transfer coefficient between the yoke and the heat pipe.Although the heat pipe is tightly fitted to the yoke, Heat is smoothly transferred to the heat pipe.

In the fourth embodiment, as shown in FIGS. 3 and 4, heat sinks 11.12 are attached to the portions 9a, 10a of the heat pipe 9.10 that protrude outside the yoke 2. Incidentally, a plan view of the heat sink 12 portion in FIG. 4 is shown in FIG. 5.

In this way, it is not necessary to attach the heat sinks 11.12 to the heat pipes 9 and 10 if the heat radiation from the heat pipes 9 and 10 is sufficient, but
Since the heat pipe 9.10 itself is originally intended to smoothly transfer heat and not to promote heat radiation, the purpose is to efficiently dissipate the heat transferred by the heat pipe 9.10 into the air. On the other hand, like this, the heat sink 11
．． If heat pipes 9a and 10a are used, the problem arises that the mass of the print head is increased as in the prior art, which may impede the high-speed transport drive of the print head, but heat pipes 9a and 10a Heat sink 11.12
Since the heat pipe is transferred to the entire print head, there is no need for a large heat dissipation plate to be attached to the entire print head, and a small one is sufficient, so there is no problem with the heat pipe.The heat pipe itself is small and lightweight and is sold in various versions. Therefore, in any case, the mass of the heat pipe itself does not affect the high-speed transport drive performance of the print head.

Effects of the Invention As explained above, the present invention radiates heat generated in the print head extremely efficiently and quickly, making it possible to provide a print head that can withstand severe continuous printing conditions. To easily achieve high-density mounting of heads. As a result, a print head with a large number of dots can be designed to be compact, contributing to high-speed printing, which is the most important issue for print heads.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of the invention and a first embodiment, FIGS. 2 to 4 are sectional views showing other embodiments, and FIG. 5 is a heat dissipation diagram in FIG. 4. FIG. 6 is a plan view showing the plate portion, and FIG. 6 is a sectional view showing the basic structure of a conventional print head. In each figure, l is a permanent magnet, 2 is a yoke, 3 is an electromagnetic mechanism, 4 is a leaf spring, 5 is an armature, 6 is a printing hammer, 7.8, 9.10 is a heat pipe, and 11.12 is a heat sink. show. Agent Patent Attorney Toshikazu Nagai 6 Printing 8-marker

Claims (5)

[Claims] (1) The magnetic path of the permanent magnet is composed of the permanent magnet, the yoke, the core of the electromagnetic mechanism, and the spring-supported armature,
A hole formed in the yoke is used in the print head where the coil of the electromagnetic mechanism is energized to cancel the magnetic flux caused by the permanent magnet, the armature is released by the spring elasticity, and a printing hammer provided on the armature performs a predetermined printing operation. A heat dissipation device for a print head, characterized in that a part of a heat pipe is tightly fitted into the print head. (2) A part of the yoke of the print head is configured as a tubular part in the center of the print head, and a part of the heat pipe is tightly fitted into the pipe of the tubular part. Print head heat dissipation device. (3) The heat pipe is bent in the middle, and a part of the heat pipe is tightly inserted into the yoke so that the bent part or end is located vertically above the part where the heat pipe is tightly inserted into the yoke. A heat dissipation device for a print head according to claim (1) or (2). (4) Claim No. (1) in which a paste-like thermal conductor is interposed on the contact surface of the part that fits tightly into the yoke of the heat pipe.
2. A heat dissipation device for a print head according to item 1, item (2), or item (3). (5) Claims (1) and (1) in which a heat sink is attached to the portion of the heat pipe that protrudes outside the yoke.
The heat dissipation device for the print head according to item 2), item (3), or item (4).