JPH06115109A - Impact dot head - Google Patents

Abstract

PURPOSE:To prevent breakage of a wire from occurring even when an impact dot head passes an end face of printing paper while carrying out printing operation. CONSTITUTION:A guide holding part 250 of a nose guide 18 holding guide 6 is formed in a platy state of two sheets, and the tip guide 6 is held in a freely swingable manner in a printing column direction by deforming the guide holding part elastically. Since the guide holding 250 of the nose guide 18 is elastically deformed and the tip guide 6 is displaced thereby even under a state wherein setting of a printing region is mistaken to start printing operation from a position off from the printing paper, and an impact dot head passes an end face of the printing paper while carrying out printing operation, breakage of a wire can be prevented from occurring.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional impact dot head is shown in FIG.
It shows in FIG. As shown in FIG. 8, the impact dot head protrudes the wire 8 while moving in a direction parallel to the platen 12 in the direction perpendicular to the plane of the drawing, and the printing paper 1 on the platen 12 is moved.
9 is a printing element that forms dots by applying an impact force to the ink via the ink ribbon 21. Here, in order to form dots at predetermined positions on the printing paper 19, the wire 8 is connected to the intermediate guide 7
And the tip guide 6 slidably arranged and supported.

As a method of attaching the tip guide 6 to the head body, a method proposed in Japanese Patent Laid-Open No. 2-530 is known. This impact dot head is shown in Figure 9.
As shown in FIG. 3, the tip guide 6 and the intermediate guide 7 are inserted into the nose guide 18, and the nose guide 18 has an oval window 30 that fits the shape of the tip guide 6 inserted into the nose guide 18. It is attached to the provided metal nose 1. Positioning of the tip guide 6 is performed by the tip guide groove 23 of the nose guide 18 in the direction perpendicular to the printing paper, and the oblong window portion 3 of the nose 1 in the direction parallel to the printing paper.
It is done at zero.

[0004]

In the impact dot printer, when the print area is erroneously set and the print operation is started from a position deviated from the print paper, the impact dot head moves the end surface of the print paper while performing the print operation. There is a phenomenon that the wire 8 is broken under the condition of passing.
In recent years, the diversification of printing paper has advanced, printing has started to be performed on thick printing paper such as thick paper and copy slips with a large number of sheets, and wire breakage frequently occurs at the end face of the printing paper, which is a problem. Was there. The mechanism of wire breakage that occurs when the impact dot head passes the end surface of the printing paper during the printing operation will be described below. 10 is a plan view of section F in FIG. As shown in FIG. 10, when the impact dot head starts the printing operation from a position deviated from the printing paper 19, and the wire 8 is driven while moving from the left to the right in the figure and jumps out to pass the end surface of the printing paper 19. , The wire 8 collides with the end surface of the printing paper 19 and receives the force A. As a result, the wire 8 is bent, and the wire 8 receives the reaction force B from the guide hole 32 provided in the tip guide 6. Here, when the coefficient of friction between the wire 8 and the ink ribbon 21 is α and the coefficient of friction between the wire 8 and the tip guide 6 is β, X in the drawing of FIG.
The friction force C in the direction opposite to the return direction of the wire 8 indicated by the direction
And D act on the wire 8. These frictional forces C (=
The return operation of the wire 8 is hindered by αA) and D (= βB), and the impact dot head continues to move from left to right in the figure while the wire 8 is protruding, so that the wire 8 is further bent. It will be. As a result, if the bending stress of the wire 8 exceeds the allowable stress, the wire 8
Will be broken, and thereafter, dots will be missing and normal printing cannot be performed.

In FIG. 10, the case where the printing operation is performed from the position deviated from the left edge of the printing paper to the right has been described as an example, but the case where the printing operation is performed from the position deviated from the right edge of the printing paper to the left also. It is the same.

As a method of avoiding the above wire breakage in the conventional impact dot head, there is a method of increasing the spring force of the return spring 15 shown in FIG. 8 to remarkably increase the return force of the wire 8. However, due to the large restoring force, a very large driving current is required to obtain a sufficient printing force. Therefore, there is a problem that the power supply capacity must be increased, and the heat generation of the head also increases with an increase in the drive current, and the impact dot head passes the end surface of the print paper while printing. The wire breakage that occurred during the operation was practically unavoidable. The present invention has been made to solve the above-mentioned conventional problems. The printing area is erroneously set, the printing operation is started from a position deviated from the printing paper 19, and the impact dot head performs the printing operation. It is an object of the present invention to provide a highly reliable impact dot head in which wire breakage does not occur even when passing through the end face of 19.

[0007]

In order to solve the above problems, the impact dot head of the present invention is characterized in that the guide support portion of the nose guide is formed by two plate members which are elastically deformable.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view of an impact dot head according to the present invention, FIG. 2 is a front view, FIG. 3 is a plan view as seen from E in FIG. 1, FIG. 4 is a cross-sectional view taken along line FF in FIG. 2, and FIG.
6 is a perspective view of the nose guide 18. FIG. The guide support portion 250 of the nose guide 18 is provided with a tip guide groove 23, and the tip guide groove 23 holds the tip guide 6, and the tip guide 6 arranges the wires 8 at predetermined positions. Further, the guide supporting portion 250 of the nose guide 18 is provided with an intermediate guide groove 24, and the intermediate guide groove 24 holds the intermediate guide 7. The nose guide 18 is inserted into the nose 1, and the tip guide 6 held by the nose guide 18 is inserted into the window portion 30 of the nose 1. The window portion 30 only guides the upper and lower ends of the tip guide 6, and Guide 6
The left and right ends of the nose 1 have a gap with respect to the window portion 30 of the nose 1. A printed wiring board 10 is arranged on the frame 2 via an insulating member 9. The frame 2 has a cylindrical shape, and a plurality of frame core portions 14 are erected parallel to each other from the bottom surface thereof. These frame core parts 1
A coil 20 is attached to the printed wiring board 4
It is connected to 0. A spring holder 13 is attached to the inner ring portion 11 of the frame 2.
The spring holder 13 is equipped with the same number of return springs 15 as the frame core portion 14, and at the same time, the guide groove provided in the spring holder 13 guides the tip end portion of the lever 16. Next, the first yoke 3 and the second yoke 4 are attached to the upper surface of the frame 2 (on the left side in FIG. 4), and the frame core portion 1 is formed by the first yoke 3 and the second yoke 4.
The lever 16 facing 4 is positioned. Wires 8 are fixed to the tips of these levers 16,
The return spring 15 urges the return direction. In addition, the damper holder 5 is brought into contact with the upper surface of the spring holder 13
The damper 17 is attached to the center of the damper holder 5, and the rear end of the tip of the lever 16 is in contact with the damper 17. At the same time, a fulcrum pressing spring 22 is attached to the damper holder 5, and the lever 16
The fulcrum is elastically supported.

In such a structure, the coil 20 connected to the printed wiring board 10 is selectively energized according to a print signal, and the magnetic flux excited by the coil 20 is the frame core portion 14, the frame 2, and the first yoke 3. , The second yoke 4, the lever 16 and the loop returning to the frame core portion 14. As a result, the frame core portion 14 and the lever 1
A magnetic attraction force acts between the wire 16 and the lever 16 to advance the lever 16, and the wire 8 fixed to the tip of the lever 16 gives an impact force to the printing paper 19 on the platen 12 via the ink ribbon 21 to form dots. After the dot formation, the lever 16 shifts to the returning operation by the spring force of the returning spring 15, collides with the damper 17 supported by the damper holder 5, and returns to the standby state.

In a printer having an impact dot head having such a configuration, the print area is erroneously set, the printing operation is started from a position deviated from the printing paper, and the impact dot head moves while the printing operation is performed. The case of passing through the end face will be described with reference to FIG. FIG. 7 is a plan view in section G of FIG. 4, showing a state in which the impact dot head starts the printing operation from a position displaced from the printing paper 19, and the wire 8 is driven and popped out while moving from left to right in the drawing. When passing the end surface of the printing paper 19, the wire 8 collides with the end surface of the printing paper 19 and receives the force A. As a result, the wire 8 pushes the guide hole provided in the tip guide 6 to the left,
The wire 8 receives a reaction force B against this. The pressed tip guide 6 elastically deforms the guide support portion 250 of the nose guide 18 and is displaced in the direction opposite to the carriage movement direction. Assuming that the coefficient of friction between the wire 8 and the ink ribbon 21 is α and the coefficient of friction between the wire 8 and the tip guide 6 is β, the frictional force C ( = ΑA) and D (= βB) act, but the forces A and B are generated by the displacement of the tip guide 6.
Is reduced, and as a result, frictional forces C and D are reduced. Therefore, even when the impact dot head passes through the end face of the printing paper 19 with the wire 8 protruding, the wire 8 can return to the standby state without being broken. On the other hand, after passing through the end surface of the printing paper 19, the elastic force of the guide supporting portion 250 causes the tip guide 6 to move.
Returns to the center of the window portion 30 of the nose 1, so that it is possible to maintain high-quality printing similar to the conventional impact dot head.

The plate thickness of the guide support portion 250 is not limited to the uniform plate thickness shown in FIG. 5, but may be partially thinned as shown in FIG. That is, the intermediate guide 7 and the tip guide 6 are held by the thick plate portion, the mutual positional relationship between the intermediate guide 7 and the tip guide 6 is secured, and at the same time, the elasticity of the thin plate portion is utilized to make the tip guide. 6 and the intermediate guide 7 can be swingably supported. The plate thickness of the thin portion may be set so that an optimum spring force can be obtained.

The tip guide 6 is preferably made of a material having a small friction coefficient, for example, a material to which polyacetal, polypropylene, or tetrafluoroethylene fiber is added, or a material having a low friction coefficient such as an oil-containing resin. Because the friction coefficient β of the material
This is because the frictional force D can be further reduced and the impact dot head having higher wire breakage resistance can be achieved.

Although the direct attraction type impact dot head has been described above as an example, it is obvious that the present invention can be applied to a spring charge type and a piezoelectric type impact dot head.

[0014]

As described above, in the print head of the present invention, the nose guide is supported so as to be swingable in the moving direction of the carriage.
Even if the impact dot head starts printing from a position off the printing paper and passes through the end surface of the printing paper while the impact dot head is performing the printing operation, a highly reliable impact dot head that does not cause wire breakage can be obtained. is there.

[Brief description of drawings]

FIG. 1 is a side view of an impact dot head according to the present invention.

FIG. 2 is a front view of an impact dot head of the present invention.

FIG. 3 is a plan view of the impact dot head according to the present invention as viewed from E.

FIG. 4 is a sectional side view of the impact dot head taken along line FF of the present invention.

FIG. 5 is an exploded perspective view showing a nose and a nose guide portion of the present invention.

FIG. 6 is a perspective view showing a nose guide of the present invention.

FIG. 7 is a plan view showing a state where a front end guide portion of the present invention passes through an end surface of printing paper.

FIG. 8 is a sectional side view showing a conventional impact dot head.

FIG. 9 is an exploded perspective view showing a conventional nose guide portion.

FIG. 10 is a plan view showing a case where a conventional leading end guide portion passes through an end surface of printing paper.

[Explanation of symbols]

 1 Nose 2 Frame 3 First Yoke 4 Second Yoke 5 Damper Holder 6 Tip Guide 7 Intermediate Guide 8 Wire 9 Insulation Member 10 Printed Wiring Board 11 Frame Inner Ring Part 12 Platen 13 Spring Holder 14 Frame Core Part 15 Return Spring 16 Lever 17 Damper 18 Nose Guide 19 Printing Paper 20 Coil 21 Ink Ribbon 22 Support Point Pressing Spring 23 Tip Guide Groove 24 Intermediate Guide Groove 30 Nose Window 32 Guide Hole 250 Guide Support

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Tanaka 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation

Claims (1)

[Claims] 1. A carriage having a tip guide for slidably supporting a wire, a nose guide for supporting the tip guide, and a nose for accommodating the nose guide, and mounted on a carriage reciprocating along a printing paper. In the impact dot head, the guide support portion of the nose guide is formed of two elastically deformable plate-shaped members.