JPH041699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION This invention relates to a releasable dot printer head.

Technical Background of the Invention and its Problems First, Fig. 1 shows an example of the conventional patent application.
The invention described in Publication No. 49576 is shown, and includes a case 1 made of a magnetic material, a permanent magnet 2, a yoke 3,
A closed magnetic circuit is formed by the core 4, the armature 5, and the magnetic body 6, and the armature 5 is held by the plate spring 7 held between the magnetic body 6 and the case 1, and the armature 5 is rotated by the excitation action of the coil 8. Permanent magnet 2
There is a device in which the armature 5 is released from the magnetic flux and moved in the printing direction by the force of a leaf spring 7, and after impacting the needle 9 on the platen, the armature 5 is attracted to the core 4 again by the magnetic force of the permanent magnet 2.

In this device, the necessary conditions are as shown in Fig. 2, during the stroke of the armature 5 (S ₀ to S ₁ ) from when the armature 5 is stopped until the needle 9 impacts the platen, the platen is always maintained. Driving torque T ₁ of amateur 5 due to spring 7
Attraction torque of amateur 5 due to permanent magnet 2
T ₂ must be increased.

However, since the leaf spring 7 is used, the torque T ₁ that operates the armature 5 in the printing direction shows a linear change, and in order to maintain the condition of T ₁ < T ₂ in the range of S ₀ to _{S 1} At S ₀ , the difference between T ₁ and T ₂ becomes extremely large. That is, _T1 is small and the printing operation of amateur 5 is slow. Furthermore, since the supermagnetic force of the coil 8 must be increased in order to cancel out the large T ₂ , it has the disadvantage of high power consumption.

In contrast, the
The invention disclosed in Japanese Patent Publication No. 55-103978 forms a closed magnetic path by a frame 10, a permanent magnet 11, a core 12, and an armature 13 made of a plate spring fixed to the frame 10, and excites a coil 14 to cause the permanent magnet 11 to move. Release Amachiyua 13 from the magnetic flux, Amachiyua 1
3 is designed to operate in the printing direction using its own elasticity. In other words, amateur 1 using a leaf spring
3 is supported by the arc surface 15 of the frame 10, the fulcrum that supports the armature 13 changes continuously during the bending process. As a result, as shown in FIG. 5, the change in the drive torque T ₃ of the armature 13 can be brought closer to the change in the attraction torque T ₂ caused by the permanent magnet 11. Incidentally, the driving torque T ₁ by the leaf spring similar to that shown in FIG. 1 is shown on the same graph, but it can be seen that it has been improved.

However, in the case of the ones shown in Figures 3 and 4, the path that shares the magnetic path of the armature 13 by the leaf spring is long, so if it is thin like a leaf spring, the cross-sectional area of the magnetic path is too small, and it is difficult to obtain sufficient magnetic flux and attraction. I can't get power. This makes it impossible to increase the force of the leaf spring,
As a result, printing speed becomes slower. Moreover, the setting of the arcuate surface 15 that supports the armature 13 according to the bending motion of the armature 13 by the leaf spring needs to be formed in accordance with the spring characteristics, and manufacturing is not easy. In order to solve this problem, it is possible to increase the cross-sectional area of the magnetic path by fixing a magnetic material to the armature 13 made of a leaf spring, but this increases the moment of inertia of the magnetic material, and at the moment of printing, the impact force causes the magnetic material to deviates from the fulcrum of the armature 13, making the operation unstable, and since the bending part (fulcrum) of the armature 13 is fixed at one point, stress is concentrated, resulting in poor durability and an increase in the number of parts and man-hours. .

Purpose of the Invention This invention was made in view of the above-mentioned points, and it is possible to increase the torque for attracting the armature by increasing the cross-sectional area of the magnetic path, and when the armature is released from the magnetic flux of the permanent magnet, the armature is It is an object of the present invention to provide a release type dot printer head which can be operated at high speed with a large torque and which can further increase the speed by reducing the moment of inertia of the armature.

Summary of the Invention This invention uses a conical coil spring to bias the armature in the printing direction, and removes the conical coil spring from the magnetic circuit to make the armature face the core, thereby increasing the cross-sectional area of the magnetic path. This increases the attraction torque of the armature due to the magnetic force of the permanent magnet, and due to the characteristics of the conical coil spring, the torque that drives the armature in the printing direction approaches a value slightly smaller than the attraction torque.
By rotating the armature around a fulcrum located at a fixed position near the core, the moment of inertia of the armature can be reduced, and therefore the printing speed and return speed of the armature can be increased.
Furthermore, since the operation can be accelerated, it is possible to shorten the time when the coil is energized and save power. Furthermore, even when blank printing is performed with no platen present during the assembly process, etc. The structure is such that excessive movement can be prevented by a stopper and the core can be quickly attracted.

Embodiment of the Invention A first embodiment of the invention will be described with reference to FIGS. 6 to 8. Annular yoke 1 in case 16
7 is fixed. A donut-shaped permanent magnet 18 is fixed to the outer periphery of the yoke 17, and a plurality of cores 19 are fixed to the upper surface of the permanent magnet 18. These cores 19 have an L-shape in which the portions to which the coils 20 are attached have the same cross-sectional area and the area of the mounting base 21 relative to the permanent magnet 18 is large. Suction surfaces 22 of these cores 19
A chamfer 23 is provided on one outer side of the core 19, and the outer peripheral surface of each core 19 is covered with a high-strength plastic 24 such as carbon fiber-containing PPS. Therefore, a fulcrum 26 made of plastic 24 is formed on one side of the outside of the suction surface 22 to support the armature 25 in a straight line. The fulcrum 26 has a thicker plastic layer by the amount of the chamfer 23. The suction surface 22 is formed by coating the plastic 24 and then polishing it together with one surface of the yoke 17. armature 2
5 is a fixed press part 27 made of silicon steel or the like and a press part 28 made of carbon steel or the like.
The surface of the press part 28 relative to the fulcrum 26 is flat, and the plate thickness of the press part 28 is made thin to reduce the moment of inertia, but since the direction of the plate thickness is perpendicular to the direction of movement of the armature 25, the strength is sufficient. be. A needle 29 is fixed to the tip of the amateur 25.

Next, a guide holder 32 is provided which has a needle guide 30 that holds the needle 29 and an armature guide 31 that guides both sides of the armature 25. This guide holder 32 is provided with a magnetic body 33 and a presser plate 35 that presses one end of a conical coil spring 34 is screwed. The magnetic body 33 is for forming side magnetic paths extending from both sides of the armature 25 to the yoke 17. Further, a stopper 36 is fixed to the inner periphery of the yoke 17 and comes into contact with the tip of the armature 25. Another stopper 37 facing this stopper 36 is provided on the guide holder 32.

In such a configuration, the armature 25 is attracted to the attraction surface 22 by the magnetic flux of the permanent magnet 18,
When the coil 20 is excited in a direction that cancels the magnetic flux of the permanent magnet 18, the armature 25 rotates about the fulcrum 26 by the force of the conical coil spring 34, causing the needle 29 to collide with the platen. coil 2
The energization to 0 is instantaneous, and the armature 25 is returned by the magnetic flux of the permanent magnet 18, comes into contact with the attraction surface 22, and stops. At this time, the armature 25 tries to rotate in the opposite direction using the side 38 of the core 19 opposite to the fulcrum 26 as a fulcrum due to inertia accompanying the return operation, but this excessive return operation is prevented by the stopper 36.
This can be prevented by

The conical coil spring 34 that biases the armature 25 is not in the magnetic circuit, and the core 19,
Amateur 25 press parts 27, magnetic body 33,
The cross-sectional area of the magnetic path leading to the yoke 17 can be increased. Therefore, as shown in FIG. 7, the attraction torque _T2 by the permanent magnet 18 can be increased. Further, although the load of the conical coil spring 34 changes during the bending process, it has a characteristic of bringing the torque T ₄ that drives the armature 25 closer to T ₂ .
That is, when the coil 20 is energized to cancel _T2 , the armature 25 moves at high speed in the printing direction with a large torque _T4 . After turning off the current to the coil 20, the attraction torque T ₂ by the permanent magnet 18
Since this is large, amateur 25 can be returned to high speed. The fulcrum 26 of the armature 25 is close to the center of the core 19, and since the pressed part 28 is thin, the center of gravity of the armature 25 is also close to the fulcrum 26, and the moment of inertia of the armature 25 is small. Furthermore, since the center of gravity of the armature 25 is close to the fulcrum 26, the rotational action of the armature 25 about the fulcrum 26 due to the impact force of printing is extremely small, which further speeds up the return speed. Therefore, the high-speed operation of the armature 25 can shorten the time for energizing the coil 20, thereby saving power.

Also, if blank printing is performed without the platen present during assembly or adjustment,
The idle printing stroke of the armature 25 is limited to a small range of S ₁ to _{S 2} as shown in FIG. 8, and the armature 25 can be quickly attracted by the permanent magnet 18. Therefore, as shown in Fig. 8, even if T ₄ becomes larger than T ₂ when S ₂ is exceeded, there is no problem, and the characteristics of the conical coil spruring 34 can be varied, making design and manufacturing easier. can do.

Note that since the stopper 37 is not normally used, there is no need to consider collision noise or durability. It may be integrally molded with the guide holder 32.

Next, a second embodiment of the present invention will be explained based on FIG. 9. The same parts as in the previous embodiment are designated by the same reference numerals, and the description thereof will be omitted. Case 39 made of magnetic material
A donut-shaped magnetic body 40 and a guide holder 41 are assembled. A core 42 holding a coil 20 is fixed on a disc-shaped permanent magnet 18 fixed to a case 39. The armature 43 holding the needle 29 has a plunger 44 facing the core 42, and the plunger 44 is held by a magnetic body 40 so as to be slidable in the axial direction. Further, a fulcrum 45 having a semicircular cross section is formed in the armature 43 in the vicinity of the core 42 and is supported by the magnetic body 40 . A guide holder 41 that holds the needle 29 is provided with a conical coil spring 34 that biases the armature 43 in the printing direction, and is also formed with a guide rib 47 having a fulcrum 45 as its radial center. The armature 43 is formed with a curved surface having a radius that matches the guide ribs 47, and measures are taken to prevent the position of the fulcrum 45 from changing.

Therefore, the armature 43 is released from the magnetic flux of the permanent magnet 18 by the excitation action of the coil 20, and the armature 43 is released by the force of the conical coil spring 34.
3 in the printing direction. In this embodiment as well, the armature 43 is formed by the conical coil spring 34.
The driving torque of T ₄ is large. Also, plunger 4
4 and the core 42 face each other over a wide area, the outer periphery of the plunger 44 is fitted into the magnetic body 40, and the magnetic body 40 contacts the case 39 over a wide area. Therefore, the cross-sectional area of the magnetic path is large.

Effects of the Invention Since the present invention is constructed as described above, the cross-sectional area of the magnetic path can be increased to increase the attraction torque of the armature due to the magnetic force of the permanent magnet, and the characteristics of the conical coil spring can be used to move the armature in the printing direction. The driving torque can be increased as it approaches the suction torque, and the moment of inertia of the armature can be reduced by rotating the armature around a fulcrum located at a fixed position near the core. Therefore, the movement of the armature in the printing direction and the return direction can be made extremely fast, and as a result, the time for energizing the coil can be shortened and power can be saved. This has the effect that even when blank printing is performed by blocking the printing with a stopper, the armature can be quickly restored.

[Brief explanation of drawings]

Fig. 1 is a longitudinal side view showing one conventional example, Fig. 2 is a graph showing the change in the attraction torque by the permanent magnet and the driving torque by the leaf spring, and Figs. 3 and 4 show other conventional examples. FIG. 5 is a graph showing changes in the attraction torque by the permanent magnet and the driving torque by the leaf spring; FIG. 6 is a longitudinal side view showing the first embodiment of the present invention; FIG. 7
8 and 8 are graphs showing changes in the attraction torque by the permanent magnet and the driving torque by the conical coil spring, and FIG. 9 is a longitudinal sectional side view showing a second embodiment of the present invention. 18... Permanent magnet, 19... Core, 20... Coil, 22... Attraction surface, 25... Amature, 2
6...Fully point, 34...Conical coil spring, 4
2...Core, 43...Amateur, 45...Fulcrum.

Claims (1)

[Scope of Claims] 1. An armature is provided so as to be able to rise and fall freely around a fulcrum located near the attraction surface of the core, and a permanent magnet is provided in a magnetic circuit to attract the armature to the attraction surface, and an excitation action causes the armature to move up and down. A release type dot printer head, characterized in that a coil for releasing the armature from the magnetic flux of the permanent magnet is attached to the core, and the armature is biased in the printing direction by a conical coil spring. 2. An armature is provided to be able to rise and fall freely around a fulcrum located near the attraction surface of the core, a permanent magnet is provided in the magnetic circuit that attracts the armature to the attraction surface, and an excitation action causes the armature to be attached to the permanent magnet. A release type characterized in that a coil for releasing from magnetic flux is attached to the core, the armature is biased in the printing direction by a conical coil spring, and a stopper is provided for preventing excessive movement of the armature in the printing direction. Dot printer head.