JPH08290591A - Dot matrix printer - Google Patents

Abstract

PURPOSE: To improve print quality and increase the reliability of a printer by adding a twist to the part composition of a hammer bank and the structure of a printing travel system in respect of a dot matrix printer which performs printing by dot matrices of print pins. CONSTITUTION: A front yoke 17 is composed in such a manner that prevents a screwhead from projecting beyond a print pin 10 when the front yoke 17 is fixed to the base 19 by a screw 18, by concaving the 2nd face of the part where the front yoke 17 is fixed to the base 19 for differing the level, and convexing the 1st face to which a plate spring is fixed, the upper end position of the convex is provided nearer the print pin side than the upper end position of the concave of the 2nd face of the front yoke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot printer used as an output device such as a computer.

[0002]

2. Description of the Related Art The contents and problems of the prior art will be described by taking the dot printers shown in FIGS. 6, 7 and 8 as an example.

FIG. 6 is a side view of the main printing mechanism of a conventional dot printer.

FIG. 7 is a front view for explaining the print pin arrangement of FIG.

FIG. 8 is a perspective view of a conventional hammerbank.

In the figure, a hammer bank 20 is equipped with a large number of printing pins 10 fixed to the tip of a leaf spring 11 for impact printing. Each printing pin is vertically and horizontally with respect to the running direction of printing paper. They are arranged side by side at predetermined intervals in the direction (for example, like n1 to n5 shown in FIG. 7). The leaf spring 11 having the printing pin 10 is fixed to the base 19 with a screw 62 together with a front yoke 61 which is on the front surface of the leaf spring and constitutes a part of a magnetic circuit, thereby constituting a hammer bank 20 which serves as a printing mechanism. are doing.

The cylindrical platen 60 supports the printing force of the printing pin 10. The cylindrical platen 60 intermittently repeats minute rotations in synchronization with paper feeding by a driving unit (not shown). The printing paper 41 is intermittently driven and sent on a path in contact with the surface of the cylindrical platen 60.

The hammer bank 20 has the above-mentioned printing pin 1
It has a permanent magnet 13 for generating a magnetic attraction force for holding the leaf spring 11 having 0 in a non-printing position, and a release electromagnetic coil 14 provided corresponding to each print pin. The coil 14 is wound around the core portion of the comb yoke 12 that attracts the leaf spring 11 directly or via a bobbin. The release electromagnetic coil 14 is a permanent magnet 1.
By supplying a release current to cancel the magnetic field of No. 3, the leaf spring 11 having the print pin 10 is driven in each process of the forward or backward movement of the hammer bank to perform dot printing of several dot lines at a time. .

[0009]

As shown in FIG. 7, with respect to a cylindrical platen, print pins are arranged at predetermined intervals in the vertical and horizontal directions with respect to the running direction of the printing paper and the forward or backward movement of the hammer bank is performed. In a conventional dot printer that performs dot printing of several dot lines at a time in each step of, the print pin n3 (the print pin in the middle in the vertical direction with respect to the running direction of the print paper) is cylindrical as shown in FIG. If the gap between the printing pin and the cylindrical platen is adjusted so that they touch each other on the circumference of the platen, the distance between the uppermost printing pin n1 and the lowermost printing pin n5 is Δ relative to the circumference of the cylindrical platen. Since the print pin has a density difference with respect to the print pin in the middle in the vertical direction with respect to the running direction of the print paper, and the print stroke becomes longer when the print speed is increased, the leaf spring Released and there has been a problem that or cause a de-dot will not be able to follow the movement of adsorption.

Further, as shown in FIG. 6, for the cylindrical platen,
A dot printer, which is a paper feed system in which the printing area is bent, has an angle (θ1) at which the printing paper comes into contact with it and an angle (θ2) at which the printing paper is ejected after printing. In addition, there were problems such as peeling and winding of tack paper when printing tack paper.

The object of the present invention is to improve the print quality (reduce the density difference of the print density, eliminate dot loss, eliminate print misalignment), ensure stable print quality, and have a trouble-free reliability. It is to provide a highly efficient dot printer.

[0012]

Means for Solving the Problems The above-mentioned problems are: a printing pin mounted on a free end of a leaf spring for impact printing; a comb yoke for adsorbing and holding the free end of the leaf spring at a non-printing position;
A permanent magnet that generates an attractive force; a release electromagnetic coil that cancels the magnetic flux of the permanent magnet to release the leaf spring in an attracted state; a front yoke that is in front of the leaf spring and forms a part of a magnetic circuit; In a dot printer having a hammerbank, in which a fixed end of a leaf spring is fixed together with the front yoke via a screw, the front yoke has a first surface facing the leaf spring and a second surface which is a back surface thereof. A concave step is provided in the vicinity of the base fixing portion on the second surface of the front yoke so that at least the screw head of the screw does not protrude from the printing pin, and a convex portion is provided in the vicinity of the base fixing portion on the first surface side. A step is provided, and the upper end of the convex portion on the first surface side is set to the concave portion on the second surface side so that the distribution of the magnetic force lines generated from the permanent magnet is not minimized at the fixed end portion to the base of the front yoke. It is achieved by providing the printing pin side than the end.

In the dot printer having the above construction, the platen which supports the striking force of the printing pin and which is a part of the running guide of the printing paper has a flat structure with respect to the second surface of the front yoke. This is accomplished by guiding the paper to travel linearly between the printing mechanism and the platen.

[0014]

With the dot printer configured as described above, the screw head for mounting the front yoke is hidden without changing the magnetic circuit inside the cross section of the hammerbank, and the printing pin side has no protrusions other than the printing pin. In addition, it is possible to eliminate the one that gets stuck in the printing paper when a linear paper feed system is used near the printing section, and reduce problems such as errors due to paper jams, peeling of tack paper when printing tack paper, and winding. be able to.

Further, in the dot printer constructed as described above, the platen for supporting the striking force of the printing pin has a flat surface on which printing is performed, so that the printing paper can be moved vertically with respect to the running direction. Since there is no gap difference between the platen and each print pin arranged at a predetermined interval in the left-right direction, it is possible to reduce the density difference of print density.
It is possible to eliminate dot loss and print misalignment.

[0016]

The present invention will be described in detail below with reference to the drawings of the embodiments.

FIG. 1 is a side view of a hammer bank showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic distribution of magnetic flux density in a section of a hammer bank showing an embodiment of the present invention.

FIG. 3 is a perspective view of a hammerbank showing an embodiment of the present invention.

As shown in FIG. 1, the hammerbank 20 is a printing pin 10 fixed to the tip (free end side) of the leaf spring 11 for hitting printing, and the free end of the leaf spring 11 is not printed. A comb yoke 12 that attracts and holds the magnet at a position, a permanent magnet 13 that generates an attraction force, a release electromagnetic coil 14 that cancels the magnetic flux of the permanent magnet 13 and releases the attracted state, and a leaf magnet 11 on the rear surface. An adjusting plate 15 which adjusts the amount of bending of the leaf spring 11 when it is released by screwing it with an adjusting screw 15, a front yoke 17 which is in front of the leaf spring 11 and constitutes a part of a magnetic circuit, and a leaf spring. A base 1 in which the fixed end of 11 is fixed together with the front yoke 17 via a screw 18.
9 and 9.

In the front yoke 17, the screw 1
8, a concave step is provided near the fixing portion of the base 19 on the screw head side (hereinafter referred to as the second surface), and a convex step is provided near the fixing portion of the leaf spring 11 on the side that contacts the leaf spring 11 (hereinafter referred to as the first surface). The front yoke 17 and the base 19
When fixing with the screw 18, the screw 1 on the second surface side
The screw head 8 is configured so as not to protrude from the print pin 10.

On the other hand, as shown in FIG. 2, the magnetic force lines 21 generated from the permanent magnet 13 draw a closed loop in the cross section of the hammer bank 20. At this time, the positions of the upper ends of the leaf springs 11 and the convex portions on the first surface side of the front yoke 17 are set to the front so that the distribution of the magnetic force lines 21 is not minimized in the concave portions of the mounting portions of the front yoke 17 to the base 19. It is provided on the print pin 10 side with respect to the position of the upper end of the recess on the second surface side of the yoke 17.

The front yoke 17 can be formed by press molding 1% to 3% silicon steel, or can be integrally formed by metal injection molding or the like.

FIG. 4 is a side view of the vicinity of the printing mechanism section showing an embodiment of the present invention.

An ink ribbon 40 and a printing paper 41 are arranged on the front surface of the printing pin 10, and the platen 42, which supports the printing force of the printing mechanism and is also a part of the running guide of the printing paper 41, is the surface on which printing is performed. Is a flat surface, and a spacing adapted to various printing paper thicknesses is maintained between the printing pin 10 and the platen 42, and a releasing current for canceling the magnetic field of the magnet means is applied to the releasing electromagnetic coil 14. Dot printing is performed by supplying.

The printing paper 41 is attached to the hammer bank 20 by a tractor 43, an idler roller 44, and a drive roller 45.
The traveling system guides the vehicle to linearly travel between the platen 42 and the platen 42.

FIG. 5 is a side view of a hammerbank showing an embodiment of the present invention using laminated front yokes.

The laminated front yoke 50 is constructed by laminating several thin electromagnetic steel plates and laminated by a bonding method such as bonding, pressure caulking, or laser welding. By stacking the front yokes, there is an effect of reducing eddy current loss, and magnetic characteristics can be improved.

In the above-mentioned embodiment, silicon steel is used as the material of the integrally formed front yoke, and electromagnetic steel sheet is used as the material of the laminated front yoke. However, pure iron or other magnetic material may be used.

In this embodiment shown in FIGS. 3 and 8, the number of print pins is 24, but the number of print pins used in the conventional dot line printer is several tens. The same configuration as described above can be applied to a hammer bank having a few hundreds.

[0031]

As described in detail above, according to the present invention, the distribution of the magnetic field lines generated from the permanent magnet is not minimized in the concave portion of the fixed portion of the front yoke to the base forming the hammerbank. By providing the position of the upper end of the convex portion of the first surface of the yoke on the print pin side with respect to the position of the upper end of the concave portion of the second surface of the front yoke, the front yoke can be moved without changing the magnetic circuit in the hammerbank. It can be configured so that the screw head of the screw does not stick out from the print pin when the screw is fixed to the base. As a result, protrusions other than the print pins can be eliminated on the print pin side, and the print paper does not get caught when a linear paper feed system is used near the print section. It is possible to reduce problems such as peeling and winding of the tack paper, and improve the reliability of the dot printer.

Further, according to the present invention, since the front yoke is laminated, the eddy current loss can be reduced, and the magnetic characteristics can be improved.

Furthermore, according to the present invention, when the front yoke is fixed to the base forming the hammer bank with a screw, the screw head of the hammer bank is configured so as not to protrude from the printing pin, and a printing mechanism. By making the printing surface of the platen, which is a part of the running guide of printing paper, supporting the printing power flat,
There is no gap difference between each printing pin and the platen arranged at a predetermined interval in the up-down direction and the left-right direction with respect to the running direction of the printing paper, and the density difference of the printing density is reduced.
It is possible to eliminate dot loss and print misalignment, and improve print quality.

[Brief description of drawings]

FIG. 1 is a side view of a hammerbank showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic magnetic flux density distribution in a cross section of a hammer bank showing one embodiment of the present invention.

FIG. 3 is a perspective view of a hammerbank showing an embodiment of the present invention.

FIG. 4 is a side view of the vicinity of a printing mechanism section showing an embodiment of the present invention.

FIG. 5 is a side view of a hammerbank using stacked front yokes according to an embodiment of the present invention.

FIG. 6 is a side view of the vicinity of a printing mechanism section showing a conventional example.

FIG. 7 is a front view illustrating a print pin arrangement of FIG. 6a showing a conventional example.

FIG. 8 is a perspective view of a hammer bank showing a conventional example.

[Explanation of symbols]

10 is a printing pin, 11 is a leaf spring, 12 is a comb yoke, 1
3 is a permanent magnet, 14 is an electromagnetic coil for release, 15 is an adjusting screw, 16 is an adjusting plate, 17 is a front yoke, 18 is a screw, 19 is a base, 20 is a hammer bank, 21 is a magnetic field line, 40 is an ink ribbon, 41 Is a printing paper, 42 is a platen having a flat surface, 43 is a tractor, 44 is an idler roller, 45 is a drive roller, 50 is a laminated front yoke, 60 is a cylindrical platen, 61 is a front yoke, and 62 is a screw.

Claims (4)

[Claims] 1. A printing pin attached to a free end of a leaf spring for impact printing, a comb yoke for attracting and holding the free end of the leaf spring in a non-printing position, a permanent magnet for generating an attraction force, and the permanent magnet. Release magnetic coil for canceling the magnetic flux of the leaf spring and releasing the attracted leaf spring, a front yoke that is in front of the leaf spring and forms a part of a magnetic circuit, and a fixed end of the leaf spring is screwed together with the front yoke. In a dot printer having a hammer bank composed of a base fixed via a front yoke, the front yoke has a first surface facing the leaf spring and a second surface which is a back surface of the front yoke. A concave step is provided near the base fixing portion of the above so that at least the screw head of the screw does not protrude from the printing pin, and a convex step is provided near the base fixing portion on the first surface side. The upper end of the convex portion on the first surface side should be closer to the print pin side than the upper end of the concave portion on the second surface side so that the distribution of the magnetic force lines generated from the stone is not minimized at the fixed end portion to the base of the front yoke. A dot printer, which is provided in the. 2. The dot printer according to claim 1, wherein the front yoke is an integral structure of a magnetic material. 3. The dot printer according to claim 1, wherein the front yoke is constructed by laminating thin magnetic plates. 4. The dot printer according to claim 1, wherein the platen that supports the striking force of the printing pin and is a part of the running guide of the printing paper has a flat structure with respect to the second surface of the front yoke. The dot printer is characterized in that the printing paper is guided so as to travel linearly between the printing mechanism and the platen.