JPH01275053A - Wire dot printer - Google Patents

Abstract

PURPOSE:To allow an optimum gap to be maintained constantly, and prevent variation of print density, and deterioration of printing accuracy by automatically adjusting the gap by means of wire tip. CONSTITUTION:A printing head and a platen 3 are allowed to come close to each other by an automatic gap adjusting device. At that time, the gap between the tip 22 of wire and the platen 3 through paper 7 and an ink ribbon 5 disappears, as the tip 22 of wire juts out of the surface 36 of a bearing between wires. Either a printing head or the platen 3 moves backward as a result of the disappearance of the gap and then stops when the gap is as specified. The disappearance of the gap maintains the position of the wire tip 22 without being adversely affected by the wear of cores 27, springs 25, an armature 23, the platen 3 or the ink ribbon 5, or of wire 21 itself, and also by the elongation and contraction of each section due to temperature change.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] In the present invention, printing is performed at the tip of a wire using the deflection return force of a spring. Concerning print heads with automatic gap adjustment devices,
In particular, the present invention relates to a wire dot printer suitable for high-speed printing.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 58-177373, a conventional device has a print head in which the tip of a wire prints using the deflection return force of a spring, and when the spring is attracted by a permanent magnet, the tip of the wire is I haven't appeared on. Therefore, when the tip of the wire becomes worn due to printing, the tip of the wire becomes depressed from the surroundings when the spring is attracted by a permanent magnet.

[Problem to be solved by the invention]

In the above conventional technology, the tip of the wire is recessed from the surroundings, and automatic gap adjustment is performed by the distance between the platen and the tip of the wire guide frame in the print head.
No consideration has been taken to keep the wire operating distance constant for printing due to changes, and if used as is, the wire operating distance will become longer, resulting in changes in printing density and decreased printing accuracy. It's possible. In addition, wire wear must be taken into account from the beginning, and the printing speed of the wire dot printer must be determined based on the longer wire operating distance than the initial wire operating distance, as shown in Figure 7. If time t is plotted on the horizontal axis and wire displacement X is plotted on the vertical axis, the wire displacement increases from the initial xo to
It grows from o to tl. Therefore, the wire must be driven at a cycle that can be repeated for one hour t1, and since this cycle is inversely proportional to the printing speed, the printing speed must be lower than in the case of to. Particularly, when increasing the printing speed, the reduction in speed that takes into account the delay in operation time to account for this wear is a major negative factor.

An object of the present invention is to provide a wire dot printer in which print density does not change and printing accuracy does not deteriorate.

[Means for Solving the Problems] The above object can be achieved if the displacement of xo is always maintained even if the tip of the wire is worn out in FIGS. 6 and 7.

Conventional automatic gap adjustment devices bring the tip of the head, that is, the wire guide frame, into contact with the platen through the paper and ink ribbon when the paper changes, and the gap is adjusted to 0.
state, then retreat from that state, and automatically stop and fix at a predetermined gap. At this time, gap 0
Since this condition is the bearing tip of the print head, the worn wire already holds a gap at the wire tip in this condition. Therefore, when the wire is moved backward, the gap becomes larger than necessary.In order to reduce the gap XI to The gap between the tip of the wire and the tip of the wire can be set to zero. By making a constant displacement from this state, the gap with the tip of the wire is always kept constant and printing can be performed.

This is shown in FIG. 7, where the wire remains at xo even after it has been worn.

[Effect]

In the above, only the wear of the wire tip has been described, but it also covers the wear of the core, spring, armature, etc. inside the print head, the expansion and contraction due to temperature changes, the wear of the platen, and the wear of the ink ribbon. By performing automatic gap adjustment at the wire tip, the influence can be eliminated and a constant optimum gap can be maintained at all times.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

The print head 1 is attached to a carrier 9. The carrier 9 is supported by a front rail 11 and a rear rail 13, and an ink ribbon 5 is attached between the print head 1 and the platen 3. A paper 7 is inserted between the ink ribbon 5 and the platen 3.

A wire 21 for printing with dots is housed in a wire guide frame 20 and connected to an armature 23 and a spring 25. A permanent magnet 31 and a core 27 are connected to the yoke 33, and an electromagnetic coil 29 is connected to the core 27.
is installed. A bearing 3 is attached to the tip of the wire 21.
5 are provided, and the wire tip 22 protrudes from the inter-wire bearing surface 36 at the tip of the wire guide frame 20. When no current is flowing through the coil 29, the armature 23 is attracted to the core 27 by the permanent magnet 31. Therefore, the spring stores a deflection return force. When current flows through the electromagnetic coil 29, a magnetic force is generated that cancels out the attractive force of the permanent magnet, so the spring 25
is released and the stored return force causes the wire 21 to fly out, collide with the platen 3 via the ink ribbon 5 and the paper 7, and print on the paper 7.

Either the print head approaches the platen as indicated by the solid line arrow in Figure 1 by an automatic gap adjustment device (not shown), or the platen approaches the print head side as indicated by the dashed line arrow. , the print head and platen approach each other. At this time, since the wire tip 22 protrudes from the inter-wire bearing surface 36, the wire tip 22 has a gap of 0 through the paper 7 and the ink ribbon 5.
It is 2. By becoming a cap O, the print head,
Or, one of the platens may be retracted.

Retraction stops when the defined gap is reached.

In this way, the wire tip 2
2 protrudes, the state of the gap O affects the position of the wire tip 22. Core 27° Spring 25. Armature 23. Platen 3. This can be maintained without being affected by the wear of the ink ribbon 11 or the wire 21 itself, or by the expansion and contraction of various parts due to temperature changes. In this way, a constant gap can be maintained without being represented and affected by wire wear, so that an increase in the wire operating distance due to wear does not have to be considered. Therefore, the printing speed can be set based on the initial printing operation time, and the printing speed can be increased.

In addition, even if the wire is worn out, the wire operating distance can be kept constant during printing, so the printing force can be kept constant, resulting in good printing density.Also, since the operating distance can be kept constant, printing accuracy can also be maintained. It has the effect of

〔Effect of the invention〕

According to the present invention, it is possible to obtain a wire dot printer in which the printing density does not change and the printing accuracy does not deteriorate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of the print head of FIG. 1, FIG. 3 is a perspective view of the wire dot printer of FIG. FIG. 5 is a sectional view of the second embodiment, FIG. 5 is a sectional view of the third embodiment of the present invention, FIG. 6 is a sectional view of the conventional example, and FIG. 7 is an example of wire operation explanation. DESCRIPTION OF SYMBOLS 1... Print head, 3... Platen, 5... Ink ribbon, 7... Paper, 9... Carrier, 11...
・Front rail, 13... Rear rail, 21... Wire,
22... Wire tip, 23... Armature, 25
... Spring, 27 ... Core, 29 ... Electromagnetic coil,
33...Yoke, 35...Bearing, 36...Bearing surface between wires, 37...Bearing, 38...Bearing surface between wires. Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 7

Claims (1)

[Claims] 1. An armature installed between a wire and a spring,
Paper and an ink ribbon are placed between a print head and a platen, where the spring is deflected by attracting it with the magnetic force of a permanent magnet, canceled by the magnetic force generated by an electromagnetic coil, and printed with the tip of the wire by the returning force of the spring. In a wire dot printer equipped with an automatic gap adjustment device that automatically adjusts a print gap, the print head and the platen are brought close to each other with the spring being attracted by the permanent magnet for automatic gap adjustment. A wire dot printer characterized in that the tip of the wire is closer to the surface of the platen than the bearing surface between the wires of the print head.