JPS6021228Y2 - wire dot printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire dot printer that prints a dot matrix using a printing wire.

. In conventional wire dot printers, the print head was moved parallel to the platen.

For example, U.S. Patent No. 3,592,311 or U.S. Pat.
As shown in US Pat. No. 159,714, there is a printer in which the entire print head can be moved parallel to the platen using a worm or a three-dimensional cam.
In Japanese Patent No. 2436, a driving disk is provided on a base plate, and an upright pin provided on the disk engages with a grooved cam provided on the lower surface of a print head support member to rotate the disk. A printer is described which provides a rocking motion to the entire printhead.

However, even in this case, the print head moves parallel to the platen on two guide shafts.

This movement of the entire print head parallel to the platen is desirable because the print wire is always perpendicular to the platen, which provides a clear outline of each dot forming the printed character. However, since a relatively heavy wire actuator or other wire actuator was also moved, a large capacity electric motor was required to drive it.

Also, because the wire solenoid is installed at the rear of the print head opposite to the platen, it is wider than the front of the print head and has a fan-shaped or triangular shape, with the tip of the print head touching both ends of the platen. When the print head is positioned at 1, the rear part of the print head protrudes laterally from the end of the platen, so there is a drawback that the entire apparatus cannot be made smaller in relation to the printable width.

In addition, in an attempt to eliminate the above drawbacks,
There is a structure as shown in Japanese Patent No. 48008, but in this device, although the tip holding member having the print wire alignment part in the print head always moves parallel to the platen as it approaches the end of the platen. , the rear end holding member of the print head, which has a print wire guide section, a wire drive solenoid, etc., rotates around the print head pivot point supported on the carriage as a fulcrum, so that as a result, printing is performed on the end of the platen. As the head approaches, each printing wire guided by a wire drive solenoid disposed at the rear of the rear end holding member bends because the printing wire guide direction differs around the pivot joint of both members, and Unnecessary force is applied to the printing wire guide wall, and the striking direction of each printing wire energized by the wire drive wire maid during printing operation is extremely deviated from the predetermined printing direction, which is not suitable for practical use. It has a structure.

The object of the present invention is to provide a wire dot printer having a print head that moves with a novel trajectory in order to eliminate the above-mentioned drawbacks.

In other words, in this invention, instead of moving the entire print head parallel to the platen as in the past,
A pivot joint between the print head and the carriage is moved in parallel with the movement of the carriage, and at least an angular motion is made such that the rear part of the print head passes through the print head pivot joint and moves on an imaginary center line perpendicular to the platen. Basically, it is configured to perform a composite motion with a radial motion.

By adopting this motion mechanism, the straight portion of the printing wire will have an offset angle with respect to the platen that increases as it moves away from the virtual center line, but the maximum offset angle is not suitable for practical printing. It has been selected within a reasonable range.

A similar device to the present invention is Japanese Patent Application No. 52-75579 (Japanese Unexamined Patent Publication No. 54-16216) filed by the applicant, but the purpose of the present invention is to utilize the print head drive mechanism disclosed in the prior art. On the other hand, it is an object of the present invention to provide a wire dot printer which has a simple structure with a small number of parts, has good assembly workability, and can be made compact as a whole.

The present invention will be explained below based on the drawings.

1 and 2 are plan views showing the principle of a printer according to the present invention, and FIGS. 3 and 4 are plan views showing an embodiment of the present invention, and FIG. 3 shows the operation mode of the print head. A-
It is an A sectional view.

First, the principle of the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 shows the front part of the print head having a wire alignment part centered around the print head pivot part which is pivotally held by the carriage;
FIG. 2 is a plan view showing the operating principle when the front part of the print head is integrally formed with a wire guide part for guiding the print wire and the rear part of the print head having a wire solenoid serving as a print wire drive part. FIG. 3 is a plan view showing the operating principle in a case where the front part of the print head always faces the platen at right angles, and the rear part of the print head performs a swinging motion as described later.

1 and 2, a platen 1 and a print head 2 are schematically shown.

Now, as shown by the solid line of the print head 2, the longitudinal direction of the print head is moved so that its tip center S is separated by a distance 1 from point m, which is the midpoint between points a and b, which define the maximum print width of the platen 1. Assume that the direction center point is made to coincide with the perpendicular line 3 from point m, and the print head 2 is made to make an angular movement about the 0 point on this perpendicular line 3.

As it approaches point a or b, the center point S of the tip of the print head becomes as shown by an arcuate line 4, and as it moves away from point m, the distance between it and the platen 1 increases and printing becomes impossible. It ends up.

On the other hand, in order to position the center point S of the tip of the print head 2 with a distance of 1 from point a or b of the platen 1,
It is necessary to perform angular movement around the O' point, which is closer to the platen than the 0 point.

However, when the center is centered at point O', when the longitudinal center line of the print head 2 is located on the vertical 3, the center point S
is located above the platen 1, and not only cannot print, but also cannot swing between a and b.

Thus, with one fixed center point, it is impossible to provide angular movement to the print head 2 while maintaining a constant distance between the platen 1 and the center point S of the print head 2.

Therefore, as the print head 2 makes an angular movement from point m, if the center point is moved from the 0 point to the O' point, that is, in the diametrical direction of the circle formed by the angular movement, the platen 1 The printing distance between the center point S of the print head 2 and the center point S of the print head 2 can be kept almost constant at any position between points a and b.

The present invention is designed to move the print head within the maximum print width while giving the print head a combination of such angular and radial movements.

Next, as shown in FIG. 1, the entire print head, that is, the front part 2A of the print head including a wire alignment section centered on eight points, a guide section for guiding the print wire to the wire alignment section, and a print wire drive section. When the print head rear part 2B including a wire solenoid is integrally formed, the angular movement of the print head 2 means that as its tip moves from point m to point a or b, it will be positioned at the front part 2A of the print head. An angle will be created between the wire alignment portion and the platen 1, which is not desirable from the conventional point of view.

However, a recording medium and an ink ribbon (not shown) are interposed between the platen 1 and the tip of the printing wire,
Considering that they are compressed slightly during printing, it will be appreciated that there is no practical problem if the printing wires are angled to some extent with respect to the platen.

According to experimental results, the diameter of the printing wire is 0.3 groups,
When the printing stroke was set to 0.5 ya, even if the printing wire was set at a maximum of 120 degrees with respect to the perpendicular line of the platen, the printed symbol was not distorted or printed without missing dots.

Therefore, with an offset angle of this order, it is possible to sufficiently manufacture a normal journal printer with a printing width of about 50 mm.

Furthermore, as shown in FIG.
When moving the print head rear part 2B as described above, these are examples of structures in which the printing wire is always struck at right angles to the platen, but there are some examples of structures in which the printing wire is struck at right angles to the platen. When the print head drive mechanism is applied to perform the movement, the print head rear part 2B moves around the print head pivoting part so as to correct the bending degree d of the print wire, so that the print wire striking direction near the wire alignment part is It has the characteristic that the deviation of is reduced.

FIG. 3 is a plan view showing an embodiment of the present invention based on the principle shown in FIG. 1, and FIG. A cam follower 12A provided on the carriage 12 is engaged with a groove 11A of the three-dimensional cam shaft 11, which serves as a carriage reciprocating drive medium, which is rotatably supported by a frame 18, 19 at regular intervals in parallel. The carriage 12 is loosely fitted so as to fit together.

The print head 20 is approximately fan-shaped, and a plurality of relatively heavy solenoids 21 are arranged radially at the wide rear part.
Each other end of the print wire 22, one end of which is connected to the solenoid 21, is supported by a wire alignment section 20A provided at the front of the print head 20.

The wire alignment section 20A aligns the printing wires 22 extending radially from the solenoid 21 to the same vertical plane, and aligns each printing wire 22 in a straight line to the wire alignment section 20A.
It is regulated so that it protrudes from the

A pivot pin 23 is protruded from the lower surface of the wire alignment section 20A on the same vertical plane as the printing wire 22, and the pivot pin 23 is pivotally held in a pivot hole 13 provided in the carriage 12. .

A head support plate 24 is disposed on the lower surface of the print head 20, and engagement pins 25 and 26 are formed protruding from both sides of the lower surface of the rear part (lower side in FIG. 3) of the plate 24. The pivot holes 13 are connected to the pivot pins 2 through respective sleeves 27 made of a material with low resistance.
Two guides are provided symmetrically with respect to an imaginary center line passing through the center of movement of the carriage 12 so as to guide the composite movement of the angular movement and the radial movement of the print head 20 using the pivot point 30 with the carriage 12 as a fulcrum. [15, 16 are engaged and supported.

The guide groove is provided in the fixing member 17 formed through the frames 18 and 19.

As described above, the guide grooves 15 and 16 are formed so as to be inclined from the center of the moving width of the carriage 12 toward an imaginary center line that intersects the platen 10 at right angles, and to form an arc.

This shape of the guide grooves 15,16 ensures that when the carriage 12 moves from one end of the three-dimensional camshaft 11 to the other end, the print head 20 is moved in accordance with the principles of the invention shown in FIG. This is the movement locus of pins 25 and 26.

As shown in FIG. 3, when the carriage 12 is located at the left end, the engagement pin 25 is located at the left end of the guide groove 15, and the engagement pin 26 is located at the left end of the guide groove 16.

When the carriage 12 is located at the center, the engagement pin 2
5 and 26 are located at the center of each of the guide grooves 15 and 16, and the tip of the print head 20 faces the platen 10 at right angles.

As the carriage 12 moves to the right, the print head 20 also tilts to the right, and when the carriage 12 is located at the right end, the engagement pins 25 and 26 are located at the right ends of the guide grooves 15 and 16, respectively.

Analyzing the movement of the print head 20, it can be seen that this is due to an imaginary line passing through the center point of the engagement pins 25, 26 on the print head 20 and the pivot joint 30 on the carriage 12, and the movement of the carriage 12. Communication between the platen 10 passing through the center and a perpendicular imaginary line is a composite movement of angular movement and radial movement in which the platen 10 moves on the latter imaginary line.

According to the present invention, the print head is pivoted between the carriage and the print head by means of the guide regulating means formed by the engagement between the guide groove provided on the fixing member and the engagement pin protruding from the rear of the print head. With the movement of the carriage using the mounting part as a fulcrum, the rear part of the print head is slower than the front part of the print head due to a synthetic movement of angular movement and radial movement, passing through the pivot part and moving on an imaginary center line perpendicular to the platen. Since the print head moves at a high speed, the rear part of the print head hardly protrudes on either side, eliminating dead space and making the entire unit more compact.Furthermore, since the movement stroke of the rear part of the print head becomes smaller, the motor for driving the print head can also be made smaller and less expensive. A low-torque motor can be used, and the print head drive mechanism has a simple structure with a small number of parts, is easy to assemble, and can be manufactured at low cost.

In addition, in this embodiment, a specific example was described in which the entire print head including the print head tip part that performs the printing operation swings with the movement of the carriage using the carriage pivoting part as a fulcrum. The principle shown in FIG. 2 is such that the leading end always faces the platen at right angles during printing operations, and only the rear portion of the print head, including the solenoid, performs rocking motion using the pivot point of the carriage as a fulcrum. Even when applied to the print head having the structure shown in the figure, it goes without saying that it has the above-mentioned characteristics, and furthermore, since the print head moves to correct the bending degree of the print wire, the deviation of the print wire in the striking direction is also avoided. This is a great practical effect.

Further, in this embodiment, the print head guide regulating means is formed so as to be operated by engagement of two guide grooves and two retaining pins, but the guide grooves and the engaging pins trace the predetermined movement locus. If you can do it like this,
There may be a single guide groove or three or more guide grooves, and the shape of the guide groove etc. is not limited to the so-called groove shape, but may be other shapes, such as the print wire alignment shape at the front of the print head and the arrangement of the wire guide groove at the rear of the print head. are also arbitrary, and these modifications and combinations do not change the gist of the present invention.

Further, as the means for reciprocating the carriage, any known device that moves the carriage parallel to the platen may be used.

[Brief explanation of drawings]

FIGS. 1 and 2 are plan views showing the principle of the present invention, FIG. 3 is a plan view showing an embodiment of the invention based on FIG. 1, and FIG.
The figure is A-A showing the operation mode of the print head in Fig. 3.
FIG. 1.10...Platen, 2,20...
Print head, 12... Carriage, 15.16
...Guide groove, 17...Fixing member, 2
3... Pivot pin, 25.26... Engagement pin.

Claims (1)

[Scope of utility model registration request] a carriage serving as a print head driving medium disposed so as to be movable in parallel with respect to a platen that guides a recording medium; a wire alignment portion pivotably mounted on the carriage and located in front of the print head on the platen side around the pivot portion; a printing wire guide part for guiding the printing wire to the wire alignment part at the rear;
and a wire dot printer having a print head provided with a wire solenoid serving as a print wire drive unit, in which the rear part of the print head moves on an imaginary center line perpendicular to the platen through the pivot joint with respect to the drive of the carriage. a fixed member having a guide regulating means for causing a combined movement of an angular motion and a radial motion to be performed, the means having a guide groove formed symmetrically with respect to the virtual center line at the rear of the print head; and a retaining portion protruding from the rear of the print head that engages with the groove.