JPH04310754A - Impact dot head - Google Patents

Abstract

PURPOSE:To provide an impact dot head which has excellent speediness and can be obtained at a low cost. CONSTITUTION:In an impact dot head of wire free-fly method, a coil spring 15 having non-linear property is used as a coil sprint for giving return force to a print wire 14. Thus, a flying distance of the print wire is restrained to the same distance as a wire fixing method. As the flying distance of the print wire is restrained to the same distance as the wire fixing method, speediness which is the same as the wire fixing method can be realized in the impact dot head of wire free-fly method. At the same time, as it is the wire free-fly method, the impact dot head can be obtained at a low cost.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact dot head for an impact dot printer.

0002

[Prior Art] As printing wire drive systems for impact dot heads, there is a wire free flight method in which the printing wire and armature are not fixed and the printing wire can fly up to the contact length of the return spring, and a wire free flight method in which the printing wire and armature are engaged. There are two fixed wire fixing methods. The wire free flight method has the advantage of being easy to assemble and being low cost because it does not require the printing wire and armature to be fixed, but since the printing wire and armature are not fixed, it is difficult to use when the platen gap becomes large. Second, since the printing wire flies until the return spring reaches its tight length, the reciprocating time of the printing wire becomes long, making it unsuitable for high-speed printing. For this reason, high-speed printers use a wire fixing method in which a printing wire and an armature are engaged and fixed.

0003

[Problems to be Solved by the Invention] However, when such a wire-fixed impact dot head is used, brazing is generally used to fix the printing wire and armature, so heat is applied to the part where the printing wire is fixed to the armature. An affected zone is formed and the mechanical strength of the printing wire is reduced, and the fatigue strength is also reduced. For this reason, when the armature is driven for a long period of time, bending stress is applied repeatedly to the part where the printing wire is fixed to the armature, and the part where the printing wire is fixed to the armature becomes fatigued due to insufficient fatigue strength. There was a problem in that the impact dot head was destroyed, reducing the long-term reliability of the impact dot head. In addition, when fixing the printing wire and armature using the brazing method, it is difficult to accurately achieve the relative positional accuracy of the printing wire and armature, resulting in reduced fractionation and increased assembly costs. However, since it is necessary to control the hardness of the armature, there is a problem in that inspection costs are required and costs increase.

The present invention has been made to solve the above-mentioned problems, and provides an impact dot head that can be operated at high speed and at low cost.

[0005]

[Means for Solving the Problems] The present invention is characterized in that the coil spring is constructed of a coil spring having nonlinear characteristics. As a result, the flight distance of printing can be reduced to the same level as that of the fixed wire method, so an impact dot head using the wire free flight method can achieve high speeds comparable to the fixed wire method. can be provided.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an impact dot head showing an embodiment of the present invention. A plurality of cores 2a are erected on the frame 2, and a coil 7 in which copper wire is wound around a coil bobbin 9 is attached around the cores 2a to form an electromagnet. Two through holes are provided for each core 2a on the bottom surface of the frame 2, and the coil terminal 10 of the coil 7 is connected to the insulating plate 2a.
It is conductively fixed to the board 17 via soldering. A connector 19 is soldered to the bottom of the board 17, and the coil 7 is electrically connected to a driver circuit (not shown) via a cable 25.

A yoke plate 3, a spacer 4, and an armature holder 21 are laminated on the outer peripheral surface of the frame 2. A cylindrical plunger 5 made of a magnetic material is fixed to an armature 6 formed from a thin plate by caulking at a portion facing the core 2a. The armature 6 is positioned in the circumferential direction by engaging a cylindrical projection 9a provided on the coil bobbin 9 with a hole 6a of the armature 6. The tip of the armature 6 engages with a wire button 13, into which a printing wire 14 is press-fitted and fixed.

The printing wire 14 is held by a tip guide 11 attached to the nose 1, an intermediate guide 12, and a guide portion 1a provided at the rear end of the nose 1.
The tips are guided so that they are arranged in a single vertical row. A coil spring 1 having nonlinear characteristics is installed between the wire button 13 of the printing wire 14 and the guide portion 1a of the nose 1.
5 is inserted, and presses the armature 6 via the wire button 13 toward a damper 16 made of a material with excellent damping characteristics. In this embodiment, the coil springs 15 are constructed of unequal pitch coil springs.

The armature 6 does not directly contact the damper 16, but presses into contact with a damper spacer 18 made of polyimide, which has excellent wear resistance, thereby ensuring the durability of the damper portion. Damper 16 and armature holder 2
Between 1 and 1 is a fulcrum pressing spring 2 that presses the fulcrum part 6b of the armature 6 that contacts the spacer 4 toward the spacer 4.
6 is interposed. A soundproof cover 27 made of metal is mounted on the rear surface of the armature holder 21 and is pressed toward the nose 1 side by a fixed spring 8 made of a thin plate.
, yoke plate 3, spacer 4, armature holder 2
It holds 1. The fixing spring 8 engages with a protrusion 1b provided on the nose 1 and applies a fixing force to the soundproof cover 27.

FIG. 2 shows an enlarged view of a coil spring 15 according to an embodiment of the present invention. With the standby state in which the armature 6 is pressed against the damper spacer 18 as the origin, the printing wire 1
FIG. 3 shows the relationship between the displacement amount x of the printing wire 14 and the load of the coil spring 15, where x is the distance that the printing wire 4 is displaced toward the printing medium. As can be seen from FIG. 3, the spring constant increases as the load on the coil spring 15 increases.

Next, the operation will be explained with reference to FIG. In the standby state, the spring force of the coil spring 15 causes the armature 6 to
is held in a pressed state by the damper 16 via the damper spacer 18. When the coil 7 is energized in pulses, the magnetic attraction force is applied to the armature 6 and the core 2a.
Occurs between. This magnetic attraction force causes the armature 6 to
is accelerated, and the fulcrum portion 6b of the armature 6 is accelerated in the direction of arrow A.
Begins a rotational movement around . Accordingly, the print wire 14 protrudes and presses the print medium 23 against the platen 24 via the ink ribbon 22 to form dots. After the collision, the armature 6 enters a return operation due to the repulsive force at the time of the collision and the spring force of the return spring 15, and is held by the damper spacer 18 after the collision, completing one printing process.

Since this embodiment uses the coil spring 15 having the characteristics shown in FIG. 3, the load on the coil spring 15 increases at an accelerating rate as the amount of displacement of the printing wire 14 increases. Therefore, the possible displacement distance of the printing wire 14 is smaller than when a linear coil spring is used. FIG. 4 shows the relationship between the amount of displacement of the printing wire 14 and time at that time. The solid line shows the coil spring 15 of this embodiment, and the dotted line shows the conventional linear coil spring. There is not a big difference in the displacement amount of the printing wire between the two at the beginning of the flight, but when a certain displacement amount is reached, the printing wire 14 using the nonlinear coil spring of this embodiment starts to decelerate and the printing wire 14 is on standby for a short time. condition can be restored. Therefore, even if the distance between the print medium and the print wire is set to be large, the print wire 14 can return to the standby state within a short time, so that high-speed continuous driving is possible and high-speed printing can be achieved.

In this example, an unequal pitch coil spring was used as the coil spring, but a conical coil spring with varying coil diameters, a barrel-shaped coil spring, a chain-shaped coil spring, or a coil spring with varying wire diameters may also be used. A similar effect can be obtained.

[0014]

As described above, according to the present application, since a coil spring having nonlinear characteristics is used as the coil spring, the flight distance of the printing wire can be suppressed to the same level as that of the wire fixed type, and an impact dot head of the wire free flight type can be used. It is possible to achieve high speeds comparable to the wire fixed method, and because it is a wire free flight method, it is possible to provide a low-cost impact dot head.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an impact dot head showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a coil spring section showing an embodiment of the present invention.

FIG. 3 is a schematic diagram showing the relationship between the load of a coil spring and the amount of displacement of a printing wire according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing the relationship between displacement amount and time of a printing wire according to an embodiment of the present invention.

[Explanation of symbols]

1 Nose 2 Frame 3 Yoke plate 5 Plunger 6 Armature 7 Coil 9 Coil bobbin 11 Tip guide 12 Intermediate guide 13 Wire button 14 Printing wire 15 Coil spring

Claims (1)

[Claims] 1. A wire button is engaged and fixed to one end of the printing wire, the printing wire is inserted into a coil spring, one end of the coil spring is engaged with the wire button, and the wire button and the tip of the armature are engaged. The printing wire is held in a standby state, an electromagnet is disposed opposite the armature, and the armature is rotated by the electromagnet, thereby driving the printing wire from the standby state to collide with the printing medium. 1. An impact dot head that performs printing by rotating the coil spring, wherein the coil spring is a coil spring having nonlinear characteristics.