JPS61222761A - Printing element driving method for dot printer - Google Patents

Abstract

PURPOSE:To weaken the impact force at the time of collision of an armature against a damper or stopper, by a method wherein a return force attenuating current for lowering the returning velocity of an armature is passed immediately after a driving current is passed to an electromagnet for driving the armature. CONSTITUTION:A driving current A is supplied to a coil 3 of the electromagnet 4 with a timing sufficient for the maximum stroke of the armature 7. However, in the course of the returning of the armature 7, namely, before the armature 7 collides against the damper 11, the return force attenuating current B for lowering the returning velocity of the armature 7 is passed. In this way, the armature 7 is attracted by the electromegnet 4 during its return, whereby the returning velocity is lowered. Therefore, the velocity of the armature 7 at the time of colliding against the damper 11 is low, and the colliding force is small. As a result, the armature 7 is immediately stopped without bounding when colliding against the damper 11. Accordingly, since the time interval of the driving currents A may be short, the armature 7 can be driven at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to printing by a dot printer that forms dots on a recording medium by driving a printing element such as a needle, and prints characters, figures, etc. using a collection of these dots. The present invention relates to an element driving method.

Conventional technology Conventionally, among printers that use a needle as a printing element, there is an impact method in which the needle collides with the recording paper to form a dot, and an impact method in which the needle is held at the tip of the needle and brought close to the recording paper to form a dot. There is a non-impact type that uses electric or electromagnetic force to propel the ink. In either system, the needle returned to its original position after being driven is stopped by a stopper or damper. An example of this conventional dot printer head will be explained based on FIG.

First, an electromagnet 4 consisting of a core 2 and a coil 3 is provided inside the housing 1. A fulcrum 6 is formed at the end of a yoke 5 that is integral with the core 2 of the electromagnet 4. A movable iron piece 7 is rotatably provided with a portion joined to the fulcrum 6 and facing the core 2, and a needle 8 as a printing element is attached to the tip of the movable iron piece 7. The needle 8 has its tip protruding from the nose 9 of the housing 1. Further, the movable iron piece 7 is urged in a direction away from the core 2 by a compression spring 10. The back surface of the movable iron piece 7 is brought into contact with a damper 11 to determine its original position when it is stationary. Further, the back surface of the movable iron piece 7 on the fulcrum 6 side is prevented from lifting up by a pressing spring 12.

Thus, the coil 3 of the electromagnet 4 is energized with a driving current A that corresponds to the print signal, and when this energization is applied, the movable iron piece 7 is attracted to the core 2, causing the needle 8 to protrude. As a result, the needle 8 either collides with the recording paper or comes close to it, forming a dot depending on the printing method. After protruding, the needle 8 and the movable iron piece 7 return to their original positions due to the force of the compression spring 1o, but they collide with the damper 11 and are stopped at their original positions.

Problems to be Solved by the Invention As shown in FIG.
When the movable iron piece 7 is energized, it moves and drives the needle 8, but at the time of return, the return speed is high, so the impact that collides with the damper 11 is large, and the repulsive force is also large as a reaction, so the compression spring 10 is pushed. Bounce against pressure. This bouncing is repeated multiple times, and it gradually decays and comes to rest. Therefore, the next drive current A cannot be applied until the movable iron piece 7 has completely stopped, making it impossible to perform high-speed printing.

Means for Solving the Problem Immediately after applying the drive current, a return force damping current is applied to reduce the return speed of the movable iron piece. This reduces the impact force with which the movable iron piece collides with the damper or stopper.

By applying a current that dampens the action and return force, the movable iron piece is prevented from bouncing, and the time it takes for it to come to rest is extremely shortened, so even if the driving current is applied immediately, there is no problem with the printing operation, and high-speed printing is possible. It is possible to do this. Further, since the impact force of the movable iron piece on the damper etc. is small, noise generation is also suppressed.

Example An embodiment of the present invention will be described based on the drawings.

Since the structure of the dot printer head is the same as that explained with reference to FIG. 2, the explanation will be based on the structure of FIG.

This embodiment is characterized by the state in which the coil 3 of the electromagnet 4 is energized. That is, the waveform itself of the drive current A is not different from the conventional one. This drive current A is applied at a timing sufficient for the movable iron piece 7 to make its maximum stroke, but when the movable iron piece 7 is in the middle of returning, that is, the movable iron piece 7 is applied to the damper 11.
A return force damping current B is applied to reduce the return speed of the movable iron piece 7 before it collides with the movable iron piece 7. As a result, the movable iron piece 7
is attracted by the electromagnet 4 during the return, slowing down the return speed. Therefore, the speed at which the movable iron piece 7 collides with the damper 11 is low, and the impact force is small. Therefore, upon collision with the damper 11, the movable iron piece 7 does not bounce and immediately stops. Therefore, it is possible to apply the next drive current A at the same time as the movable iron piece 7 returns, and the interval at which the drive current A is applied may be short. This makes it possible to drive the movable iron piece 7 at high speed.

Therefore, the waveform of the restoring force attenuation current B has a gentle waveform in which the falling portion gradually decreases. As a result, the force acting on the movable iron piece 7 to attenuate the return force is gradually reduced, resulting in smooth operation.

In the above embodiment, a return force attenuating current is applied to the electromagnet 4 that drives the movable iron piece 7 to attract the movable iron piece 7 at the time of return to reduce the return speed. In addition to the driving electromagnet 4, a damping electromagnet is provided.

A return force attenuating current may be applied to this electromagnet.

Effects of the Invention In the present invention, as described above, immediately after the driving current is applied to the electromagnet that drives the movable iron piece, a return force damping current is applied to reduce the return speed of the movable iron piece, so that the movable iron piece does not return. When the movable iron piece is moved, it does not bounce when it hits a damper or stopper, which shortens the time it takes for the movable iron piece to stop after driving, and shortens the timing until the next drive current is applied, resulting in high-speed printing. In addition, since the impact force on the damper etc. is weak, noise generation is also low.Furthermore, the falling waveform of the return force decay current is made into a gradual waveform that gradually decreases.
This allows the movement of the movable iron piece to be made smoother, resulting in smoother operation.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are waveform diagrams showing current waveforms and displacement states of the movable iron piece according to an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional side view showing the structure of the dot printer head, and FIG. ,
) and (b) are waveform diagrams showing the current waveform and the displacement state of the movable iron piece in a conventional dot printer head. 4...Electromagnet, 7...Movable iron piece, 8...Needle (printing element), A...Driving current, B...Returning force attenuation type outflow applicant Tokyo Electric Co., Ltd. 3" Figure b

Claims (1)

[Claims] 1. An electromagnet for driving a movable iron piece holding a printing element is provided, and the printing element is moved toward a recording medium by passing a driving current corresponding to a printing signal to this electromagnet. A method for driving a printing element of a dot printer, characterized in that immediately after applying a driving current to the electromagnet, a return force damping current is applied to reduce the return speed of the movable iron piece. 2. The printing element driving method for a dot printer according to claim 1, wherein the current waveform of the fall of the restoring force decay current is made into a gentle waveform that gradually decreases.