JPH06115110A - Impact dot head - Google Patents

Abstract

PURPOSE:To prevent breakage of a wire from occurring even when an impact dot head pases an end face of printing paper while carrying out printing operation. CONSTITUTION:A guide-sliding groove 401 is provided to a nose 1 holding a tip guide 6 to hold the tip guide in a freely swingable manner in a printing column direction. Since the tip guide can be moved thereby even under a state wherein of a printing region is erroneous 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 the 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 FIG. 1 shows a conventional impact dot head.
0, shown in FIG. As shown in FIG. 10, the impact dot head protrudes the wire 8 while moving in a direction parallel to the platen 12 and in the direction perpendicular to the plane of the drawing, and gives an impact force to the printing paper 19 on the platen 12 via the ink ribbon 21 to form dots. Is a printing element that forms a. Here, the wires 8 are slidably arranged and supported by the intermediate guide 7 and the tip guide 6 in order to form dots at predetermined positions on the printing paper 19.

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 1.
As shown in FIG. 1, 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 portion 30 that fits the shape of the nose guide 18 with the tip guide 6 inserted therein. Metal nose 1 with
Is attached to. 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 by the oval window portion 30 of the nose 1 in the direction parallel to the printing paper.

[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, printing paper has become more diversified, and 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 at the edge of printing paper has become more frequent, which has become a problem. It was The mechanism of wire breakage that occurs when the impact dot head passes through the end face of the printing paper during the printing operation will be described below. FIG. 12 shows F in FIG.
FIG. As shown in FIG. 12, 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 to jump out and pass through 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, the friction coefficient between the wire 8 and the ink ribbon 21 is α, and the wire 8
When the friction coefficient between the tip guide 6 and the tip guide 6 is β, the frictional forces C and D act on the wire 8 in the direction opposite to the returning direction of the wire 8 shown in the X direction in FIG. These frictional forces C
(= ΑA) and D (= βB) hinder the return operation of the wire 8, 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 further bends. Will be As a result, if the bending stress of the wire 8 exceeds the permissible stress, the wire 8 will be broken, and thereafter, dots will be missing and normal printing cannot be performed.

In FIG. 12, the case where the printing operation is performed from the position deviated from the left end of the printing paper to the right has been described as an example. However, when the printing operation is performed from the position deviated from the right end of the printing paper to the left. It is the same.

In the conventional impact dot head, as a method of avoiding the wire breakage as described above, there is a method of increasing the spring force of the return spring 15 shown in FIG. 10 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 the increase of the drive current, and the impact dot head moves the end face of the printing paper while performing the printing operation. The wire breakage that occurred when passing 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 a groove is provided in the nose, and a tip guide is supported in the groove so as to be slidable in the carriage movement direction. To do. Further, the nose is composed of two bodies, and the tip guide is slidably held by the nose. The tip guide is slidably held between the nose and the guide frame. Moreover,
It is characterized in that when the tip guide is slidably inserted in the nose, it is retained by an elastic claw provided on the tip guide.

[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 of 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 showing a FF cross section in FIG. 2, and FIG. It is an exploded perspective view of a tip guide.

As shown in FIG. 5, the nose 1 is divided into two parts on the left and right, and a guide sliding groove 40 is provided on each of the noses 1.
1 is provided. The groove width of the guide sliding groove 401 is set to be slightly larger than the plate thickness of the tip guide 6,
The tip guide 6 can be slid along the guide sliding groove 401. Assembling is performed by first inserting the tip guide 6 into one guide sliding groove 401 of the nose 1 which is divided into two parts, and then combining the other nose 1 with the nose 1 to which the tip guide 6 is attached. According to this structure, the tip guide 6 is slidably clamped by combining the two noses 1 so that the tip guide 6 can be attached to the nose 1.
There is no need to worry about coming off. Also, in manufacturing the nose 1, since the nose 1 is composed of two bodies, the guide sliding groove 40
The process of 1 can be easily performed.

The tip guide 6 is a guide sliding groove 4 of the nose 1.
The guide slide groove 401 only guides the upper and lower ends of the tip guide 6 slidably, and the left and right ends of the tip guide 6 have a gap with respect to the window portion 30 of the nose 1. Positioning spring portions 402 are provided on the left and right sides of the tip guide 6, and the tip guide 6 is elastically positioned at the center of the nose window portion 30. As shown in FIG. 4, the intermediate guide 7 is held by the intermediate guide groove 24 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 parts 1
4 are erected parallel to each other. The coil 20 is inserted in the frame core portion 14 and is connected to the printed wiring board 10. 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 (left side in FIG. 4) of the frame 2, and the lever 16 facing the frame core portion 14 is positioned by the first yoke 3 and the second yoke 4. Has been done.
The wire 8 is fixed to the tips of these levers 16 and is urged by the return spring 15 in the return direction. Further, the damper holder 5 is attached so as to be in contact with the upper surface of the spring holder 13, and the damper 17 is attached to the center portion of the damper holder 5 and the lever 1 is attached to the damper 17.
The back surface of the tip of 6 is in contact. At the same time, a fulcrum pressing spring 22 is attached to the damper holder 5, and elastically supports the fulcrum portion of the lever 16.

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 the printer having the impact dot head having such a configuration, the printing operation is started from a position deviated from the printing paper by mistakenly setting the printing area, and the impact dot head moves the printing paper 19 while performing the printing operation. The case of passing through the end face will be described with reference to FIG. FIG. 6 is a plan view of the section G in FIG. 4, showing a state in which the impact dot head starts the printing operation from a position deviated 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 presses the guide hole 32 provided in the tip guide 6 to the left, and the wire 8 receives the reaction force B against it. The pressed tip guide 6 elastically deforms the positioning spring portion 402 and slides along the guide sliding groove 401 provided in the nose 1. 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) acts, but the forces A and B are reduced by sliding the tip guide 6, and as a result, the 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 face of the printing paper 19, the tip end guide 6 returns to the center of the window 30 of the nose 1 by the elastic force of the positioning spring portion 402, so that printing with high printing quality similar to that of the conventional impact dot head is performed. Can be maintained.

Another embodiment for slidably supporting the tip guide 6 will be described below.

FIG. 7 shows an embodiment using the tip guide frame 403. By combining the nose 1 and the tip guide frame 403, a guide groove for slidably supporting the tip guide 6 is formed. Assemble the guide receiving surface 410 of the nose 1.
Place the tip guide 6 on the nose 1 with the tip guide frame 403.
The tip guide is slidably supported by mounting it on the tip of the. According to this structure, the tip guide frame 40
3 can be made of a material different from that of the nose 1. For example, if the tip guide frame 403 is made of a wear-resistant material such as metal or ceramics, the tip guide frame 403 is worn due to friction with the ink ribbon and the tip is It is possible to prevent the guide 6 from falling off.

FIG. 8 shows ribs 4 above and below the window portion 30 of the nose 1.
This is an example in which 04 is provided and the tip guide 6 is slidably attached from the inside of the nose 1. Normally, when assembling the impact dot head, the nose 1 is placed in a direction such that the tip side (right side in FIG. 8) of the wire 8 faces downward and the components are laminated. In this embodiment, since the tip guide 6 is attached from the inside of the nose 1, the tip guide 6 may be dropped into the nose 1 during assembly. Next, the back guide frame 4
05 is dropped into the nose 1 and press-fitted, and the tip guide 6 is sandwiched and held by the rib 404 of the nose 1 and the rear guide frame.
Here, a step portion 406 is formed on the inner wall of the nose 1 so that the tip guide 6 can slide. Step 40
The step G of 6 is slightly larger than the plate thickness H of the upper and lower ends of the tip guide 6, and the rear guide frame 405 has a step portion 40.
Since it is attached in contact with 6, the tip guide 6 is not pinched and fixed.

FIG. 9 shows a through groove 40 on the upper surface of the tip of the nose 1.
7 is provided, and a concave groove 408 is provided on the lower surface of the tip portion of the nose 1 as an example. The tip guide 6 has a positioning spring portion 4
02, a retaining claw 409 is provided. Assembly is performed by inserting the tip guide 6 from the through groove 407.
The retaining claw 409 is elastically configured, and the through groove 4
When passing through 07, the retaining claw 409 is retracted, and after passing through the through groove 407, it spreads to prevent retaining. According to this structure, a special component for holding the tip guide 6 is not required, and the tip guide 6 can be slidably supported with a simple structure.

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

Although the direct suction 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 or a piezoelectric type impact dot head.

[0019]

As described above, in the print head of the present invention, since the tip guide is supported so as to be swingable in the moving direction of the carriage, the print area is erroneously set and printing is performed from a position displaced from the printing paper. There is an effect that a highly reliable impact dot head in which wire breakage does not occur even when the operation is started and the impact dot head performs the printing operation and passes through the end face of the printing paper.

[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 tip guide of the present invention.

FIG. 6 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. 7 is an exploded perspective view showing a nose and a tip guide of the present invention.

FIG. 8 is a sectional side view showing a nose and a tip guide of the present invention.

FIG. 9 is an exploded perspective view showing a nose and a tip guide of the present invention.

FIG. 10 is a sectional side view showing a conventional impact dot head.

FIG. 11 is an exploded perspective view showing a conventional nose guide portion.

FIG. 12 is a plan view showing a state 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 section 32 Guide hole 401 Guide sliding groove 402 Positioning spring section 403 Tip guide frame 404 Rib 405 Rear guide frame 406 Stepped portion 407 Through groove 408 Concave groove 409 Locking claw 410 Guide receiving surface

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

Claims (4)

[Claims] 1. An impact dot head mounted on a carriage that reciprocates along a printing paper, having a tip guide that slidably supports a wire and a nose that supports the tip guide. An impact dot head provided, wherein the tip guide is supported in the groove so as to be slidable in a carriage movement direction. 2. The impact dot head according to claim 1, wherein the nose is composed of two bodies, and the tip guide is slidably held by the nose. 3. The impact dot head according to claim 1, wherein the tip guide is slidably held between the nose and the guide frame. 4. The impact dot head according to claim 1, wherein when the tip guide is slidably inserted in the nose, the stopper is provided by an elastic claw provided on the tip guide.