JPH0639170B2 - Print head - Google Patents

Description

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

2. Description of the Related Art In recent years, an inexpensive clapper-integrated print head has been used as a print head for a dot printer.

The conventional print head will be described below with two examples.

FIG. 3 is a sectional view of a conventional print head. 1 is an armature, 2 is a print wire welded and fixed to the movable end of the armature 1, and 3 is a magnetic force that attracts the armature 1 to print on the print wire 2. It is an electromagnet.
The armature 1 can swing about the outer end of the electromagnet 3 as a fulcrum. Reference numeral 9 denotes a resin-molded stopper having the shape shown in FIG. 4, and the armature 1 is constantly pressed against the stopper 9 by a spring 5. 6 is a pressing spring that presses the armature 1 against the fulcrum of the electromagnet 3, 7 is a cover of the print head, and 8 is a support member that presses the stopper 9 and the pressing spring 6 against the cover 7.

The operation of the print head configured as described above will be described below.

First, the armature 1, which was pressed against the stopper 9 by the spring 5 in the initial state, is attracted when the electromagnet 3 is excited, and swings with the outer end of the electromagnet 3 as a fulcrum.
At the same time, the print wire 2 welded and fixed to the movable end of the armature 1 operates to perform the print operation.

Next, when the excitation of the electromagnet 3 is completed, the armature 1 and the printing wire 2 are pushed back by the spring 5, and the stopper 9
Bounce on and return to the initial state.

Next, FIG. 5 is a cross-sectional view of another conventional print head.
1 is an armature, 2 is a print wire, 3 is an electromagnet, 5
Is a spring, 7 is a cover, and 8 is a supporting member, which have the same construction as the above-mentioned conventional example, and therefore, the same reference numerals as those in the above-mentioned conventional example are given and the description thereof is omitted. Reference numeral 10 is a resin-molded stopper that has an O-ring guide in the peripheral portion and is supported on the outer periphery of the print head, and 11 is an O-ring that presses the armature 1 against the outer end of the electromagnet 3.

The operation of the print head having the configuration of the other conventional example described above is the same as that of the above-described conventional example.

Problems to be Solved by the Invention However, in the conventional configuration, the stopper is a resin molded product, and the dimensional properties depend on the molding conditions.
There is a problem in that the thickness and elasticity of the portion where the armature abuts are not constant in the circumferential direction, which deteriorates the printing quality.

This is because when a plurality of print wires perform printing at the same time, the swing stroke changes if the thickness and elasticity of the stopper 9 are different in the circumferential direction, so the arrival time on the print paper is not uniform, but the print head Since printing is performed while moving on the printing paper, the deviation of the arrival time of the printing wire will cause the deviation of dots and the printing quality will deteriorate.If the strokes are not uniform, the final speed of the printing wire will change and the printing pressure will change. This means that variations occur and the print quality deteriorates.

Means for Solving the Problems In the print head according to the present invention, a sheet-like elastic member is used as a stopper, positioning holes are provided in a cover, a presser spring, and a stopper, and a positioning protrusion is further provided in a supporting member, Stopper, presser spring,
The positioning holes of the cover are fitted together, and the pressing spring and the stopper are sandwiched between the cover and the supporting member to assemble.

Operation According to the above configuration, the sheet-like elastic body originally has uniform thickness and flatness, and if this is punched out and used as a stopper, the swing stroke of all armatures can be made uniform, and the printing wire Takes a uniform time to reach the print medium, and as a result, the strength with which the print medium is hit becomes uniform.

Further, since the positioning protrusions of the support member are fitted to the positioning holes of the stopper, the pressing spring, and the cover, the respective parts can be assembled easily and accurately.

Furthermore, since the pressing spring and the stopper are sandwiched between the cover and the supporting member, the pressing spring and the stopper are fixed by surface contact, and the fulcrum of the pressing spring is stably fixed even when the armature makes a high-speed striking operation. The stopper can maintain its stopper position stably without shaking or resonating.

Embodiment FIG. 1 is a sectional view of a print head in one embodiment of the present invention. Reference numeral 1 is an armature, 2 is a print wire, 3 is an electromagnet, and 5 is a spring. These are the same as the components of a conventional print head, and are denoted by the same reference numerals as those of the conventional print head and will not be described.

Reference numeral 6 is a holding spring having a plurality of positioning holes, 7 is a cover having a plurality of positioning holes, and 8 is a support member having a plurality of positioning protrusions. Reference numeral 4 denotes a stopper formed by punching out a sheet-like elastic body and having an annular shape having a plurality of positioning holes (see FIG. 2).

The positioning protrusion of the support member 8 is fitted with the positioning holes of the stopper 4, the pressing spring 6, and the cover 7, and the pressing spring 6 and the stopper 4 are sandwiched between the cover 7 and the supporting member 8 and assembled. Is.

The operation of the print head configured as described above will be described below.

First, the armature 1, which was pressed against the stopper 4 by the spring 5 in the initial state, is attracted when the electromagnet 3 is excited and swings with the outer end of the electromagnet 3 as a fulcrum.
At the same time, the printing wire 2 welded to the movable end of the armature 1 operates to perform the printing operation.

Next, when the excitation of the electromagnet 3 is completed, the armature 1 and the printing wire 2 are pushed back by the spring 5, and the stopper 4
Bounce on and return to the initial state.

Here, in this embodiment, the stopper 4, the pressing spring 6 and the cover 7 are provided with positioning holes, and the supporting member 8 is provided with a positioning projection, and the positioning projection of the supporting member 8 is provided with the stopper 4, the pressing spring 6 and the cover 7. Since each positioning hole is fitted and assembled, it is possible to easily assemble with high assembly accuracy.

Furthermore, since the stopper 4 is made of a sheet-shaped elastic member, the stroke of the armature 1 swinging is uniform over the entire circumference.

Further, since the pressing spring 6 and the stopper 4 are sandwiched between the cover 7 and the support member 8, the pressing spring 6 and the stopper 4 are fixed by surface contact, and even if the armature 1 is hit at high speed, the pressing spring 6 is pressed. Since the fulcrum is stably fixed, the armature 1 is surely supported by the pressing spring 6 at its fulcrum, and as a result, the swinging stroke of the armature 1 becomes more uniform and stable.

Furthermore, as a result of the above-mentioned surface contact fixation, even if the armature 1 strikes at a high speed, the stopper 4 can maintain its stopper position stably without shaking or resonating. The oscillating stroke of is more stable. Therefore, when a plurality of printing wires print at the same time, the printing wires reach the printing paper at the same time. For this reason, dot deviation does not occur due to the difference in arrival time.

Further, since the strokes are uniform, the final speeds of the printing wires are the same, and printing is performed with uniform printing pressure.

EFFECTS OF THE INVENTION Since the present invention is configured such that the positioning projections of the support member are fitted with the positioning holes of the stopper, the pressing spring, and the cover, the assembly can be easily performed with high assembly accuracy.

Further, since the sheet-like elastic member is used as the stopper, the swinging stroke of the armature can be made uniform over the entire circumference.

Further, since the pressing spring and the stopper are fixed by the surface contact between the cover and the supporting member, even if the armature strikes at a high speed, the armature is surely supported by the pressing spring at its fulcrum portion. The stopper can maintain its stopper position stably without swinging or resonating, so that the swinging stroke of the armature can be further stabilized.

Therefore, it is possible to provide a print head which is easy to assemble and can realize excellent print quality.

[Brief description of drawings]

FIG. 1 is a sectional view of a print head according to an embodiment of the present invention, and FIG.
FIG. 3 is a plan view of a stopper of a sheet-like elastic member, FIG. 3 is a sectional view showing an example of a conventional print head, FIG. 4 is a plan view of a stopper for supporting an inner side of a molded product, and FIG. 5 is a conventional print head. FIG. 6 is a cross-sectional view showing another example, and FIG. 6 is a plan view of a stopper for supporting the outer side of the molded product. 1 ... Armature, 2 ... Printing wire, 3 ... Electromagnet, 4 ... Sheet elastic member stopper, 5 ... Spring, 6 ... Pressing spring, 7 ... Cover, 8 ... Supporting member, 9 ... … Inner support stopper, 10 …… Outer support stopper, 11 …… O-ring

Claims (1)

[Claims] 1. An armature radially arranged with its movable end facing inward and biased toward the return side, and a print wire respectively arranged at the movable end of the armature.
An electromagnet for selectively driving the armature, a support member having a positioning projection, a cover having a positioning hole fitted to the positioning projection of the support member, which abuts the pressing biasing member and covers the back surface of the print head, A pressing biasing member having a positioning hole fitted to the positioning protrusion of the supporting member, one surface of which abuts against the sheet-shaped elastic member and which biases each fulcrum portion of the armature toward the electromagnet.
A sheet having a positioning hole fitted to the positioning protrusion of the support member and arranged such that a part of the surface of the sheet-like elastic member contacts the support member and also contacts the movable end of the armature when the armature returns. Print head having a shape elastic member.