US3848719A

US3848719A - Printing device comprising electro-magnets

Info

Publication number: US3848719A
Application number: US00053418A
Authority: US
Inventors: L Milan
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1970-07-09
Filing date: 1970-07-09
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

Device for printing dots selected from series of dots arranged on a line, comprising a from a of separately energizable electromagnets having movable cores, the pulses of which are transferred to printing styli striking a printing surface. According to the invention said electro-magnets, arranged in a common cage parallel to each other in the direction of striking, have their cores prolonged by pushing members acting upon levers arranged substantially along radii from the striking zone, said levers bearing on the periphery of said cage and holding at their free ends said printing styli and exerting on said cores an elastic pressure in the direction towards their rest positions.

Description

United States Patent [19] Milan Nov. 19, 1974 PRINTING DEVICE COMPRISING ELECTRO-MAGNETS [75] Inventor: Lucien Milan, Garches, France [73] Assignee: U.S. Phillips Corporation, New

York, N.Y.

[22] Filed: July 9, 1970 [21] Appl. No.: 53,418

[52] 11.8. CI 197/1 R [51] Int. Cl B41j 3/44 [58] Field of Search 197/1 R; 101/93 C [56] References Cited UNITED STATES PATENTS 3,099,711 7/1963 Foley et a1. 197/1 R X 3,209,681 10/1965 Sanborn 197/1 R X 3,243,031 3/1966 Przysiecki 197/6.l 3,254,750 6/1966 Goldner 197/6.l 3,467,232 9/1969 Paige 197/] R FOREIGN PATENTS OR APPLICATIONS 1,577,409 8/1969 France 197/1 R 537,343 6/1941 Great Britain 197/1 R Primary ExaminerRobert E. Pulfrey Assistant Examiner-R. T. Rader Attorney, Agent, or Firm-Frank R. Trifari 57 ABSTRACT Device for printing dots selected from series of dots arranged on a line, comprising a from a of separately energizable electro-magnets having movable cores, the pulses of which are transferred to printing styli striking a printing surface.

According to the invention said electro-magnets, arranged in a common cage parallel to each other in the direction of striking, have their cores prolonged by pushing members acting upon levers arranged substantially along radii from the striking zone, said levers bearing on the periphery of said cage and holding at their free ends said printing styli and exerting on said cores an elastic pressure in the direction towards their rest positions.

1 Claim, 6 Drawing Figures PAIENIEL HH 3.848.719

SHEEI 1 OF 2 INVENTOR.

LUCIEN MiLAN AGENT PATENTELXJV 1 W4 3.848.719

SHEET 2 OF 2 INVENTOR. 1

LUCIEN MILAN 2 I l. C

AGENT PRINTING DEVICE COMPRISING ELECTRO-MAGNETS This invention relates to a device for printing dots selected from a series of dots arranged in lines, said device comprising a set of separately energizable electromagnets having movable cores, the pulses of which are transmitted to printing styli striking a printing surface.

Among the printing means employed, for example, as output members of computers, termed printers, some of them print the characters in the form of dots. The dots are printed bymeans of printing styli in consecutive, parallel lines or columns, while a series of styli arranged in columns and selected by number and place for representing a portion of a character simultaneously receive a pulse. The characters may be formed by dots selected from the thirty five dots of a group of five columns of seven dots each.

These printers must in the first place have a high printing rate, preferably with a minimum of volume. A known printing device (from French Patent Specification No. 1,405,348) uses a series of electro-magnets energized selectively, the movable cores of which are prolonged by flexible wires, the ends of which serve as printing styli. Such a device, though working at a comparatively high rate, has a non-negligible volume and its reliability is limited by wear of said flexible wires in their guides. The device is highly exposed to external influences. Moreover, the various wires of the same set do not cover the same trajectories and the stroke of the printing styli is not perfectly homogeneous.

The present invention has for its object to provide a printing device comprising electro-magnets and printing styli, whose printing rate is higher than that of the aforesaid devices, the reliability being improved, the volume being reduced, the stroke being homogeneous and the protection from external influences being improved.

According to the invention the device is characterized in that said electro-magnets arranged in a common cage parallel to each other in the direction of striking, have their cores prolonged by pushing members acting upon levers arranged substantially along radii from the striking zone and bearing on the periphery of said cage and holding at their free ends said printing styli and exerting on said cores an elastic pressure in the direction to their rest positions.

In an advantageous embodiment of the invention the working point of said pushing member is located substantially at equal distances from the stylus and from the fulcrum of each lever.

In a further preferred embodiment of the invention the cage in which the electro-magnets are accommodated is cylindrical, whilst the electro-magnets are arranged in a circle.

In a still further preferred embodiment of the invention the levers are formed by elastic rods rigidly held at one end, the other end being bent over at right angles in the form of a printing stylus.

In a further preferred embodiment the levers are formed by tongues punched from an elastic, flat disc fixed to the periphery of said cage and pointing towards the centre of the cage, the end of each tongue being provided with a printing stylus.

In a further preferred embodiment of the invention the levers are rigid and pivotable at their fulcrum, each of said levers co-operating with a spring the force of which acts opposite the pulses of said electro-magnets.

The following description given with reference to the accompanying drawings will show how the invention may be carried into effect.

FIG. 1 is a perspective view of a device in accordance with the invention.

FIG. 2 is a sectional view taken on the line B-B in FIG. 3 of a device in accordance with the invention in a first embodiment.

FIG. 3 is a cross sectional view taken on the line A-A in FIG. 2 of the same device.

FIG. 4 is a sectional view taken on the line CC in FIG. 5 of a device in accordance with the invention in a second embodiment.

FIG. 5 is a front view of the device shown in FIG. 4.

FIG. 6 is a partial sectional view taken on the axis of the drum of a device in accordance with the invention in a third embodiment.

The device shown in FIG. 1 is accommodated in a cage 1 closed by a lid 2, secured, for example, by screws 5. The lid 2 is pierced by a gap 3 through which printing styli 4 are passed.

In FIG. 1 the number of printing styli amounts to seven. Two of them are shown in the striking position. These styli are formed by rigid rods arranged in parallel closely adjacent each other: the gap 3 guides them in common. From FIG. 1 it will be seen that the device according to the invention ensures complete protection of the movable elements therein: the electro-magnets, the levers, the styli, against external influences.

These movable elements are shown in the sectional views of FIGS. 2 and 3; they are circular arranged'in the cylindrical cage 1 made of magnetic material preferably having high permeability. This circular dispo sition, which can be carried out in a simple manner, facilitates the manufacture of a high-precision device. In the cells 6 of the cage 1 are accommodated the coils 7, along the axes of which the magnetic cores 8 are adapted to move. These cores 8 are prolonged by pushing rods 9 of non-magnetic material, guided in rings 10 which complete the magnetic circuits.

The pushing rods 9 act each on an elastic rod 11, which is held at 12 between the cage 1 and its lid 2 and bent over substantially at right angles at 13 in order to form a printing stylus such as 4. The material and the section of these rods ensure a sufficient elasticity for resetting the cores of the electromagnets and for holding them in the rest position. This embodiment is conspicuous by its great simplicity and reduced cost offabrication. The reliability of the device is guaranteed by the simplicity of the parts. Frictions are minimized and wear is negligible.

FIGS. 1 to 3 show a device comprising seven printing styli, but as a matter of course an identical embodiment may be made for devices comprising a different number of styli.

The ends of the rods 11 forming the printing styli are flush with the surface of the lid 2 in their rest position. This position is determined by a stop at which each electro-magnet is returned by the elastic pressure of the corresponding rod 11; this stop is formed in this case by a washer or circlip l4 bearing on the ring 10' and being arranged on each pushing rod 9.

A cap 15 protects the rear side of the device. This cap may furthermore hold the output connections of the windings 7.

The arrangement of the group of electro-magnets of the device according to the invention occupies a minimum space, since the electro-magnets are disposed parallel to each other.

The action of the pushing members on the printing styli via levers provides, with the same track of the styli, a reduction of the tracks of the electro-magnets. This reduction corresponds to an equivalent reduction of the gap of the electro-magnets in the rest position so that the response time is shorter, the flyback time may be shorter and with a given type of electro-magnet the force may be higher. The risks of bouncing and vibrations are reduced.

In the variation shown in FIGS. 4 and 5 the rods 11 of the device described above are replaced by tongues 24 punched from a washer 20, which is held at its periphery between the drum 21 and a lid 22 secured by screws 19. The lid 22 has a passage 23 for the desired number of aligned styli, in this embodiment nine. The elastic tongues 24 point towards the axis of the device, each tongue having secured to it, for example, by electric welding at 27, a bent-over rod 25 to form a printing stylus at 26.

This embodiment, exhibiting a great simplicity, permits the use of different materials for the levers and for the printing styli so as to match their individual functions perfectly. This embodiment provides, in addition, the other advantages of the aforementioned embodiment.

The printing pulses are imparted to the styli by means of the electro-magnets described with reference to FIGS. 2 and 3, comprising a coil 28, a movable core 29, a pushing member 30, an abuttment washer 31, a guiding ring 32 of magnetic material. The external magnetic circuit of each electro-magnet is formed by a hollow cylinder 33 of magnetic material. The cylinders 33 are mounted in the cage of the drum 21, made in this case of non-magnetic material. Plugs 34 complete the protection of the device.

The body of the drum 21 comprises an eccentric portion 35 provided with cushions 36 serving as guide members along a bar 37 and bearing on a slide 38, while the body of the cage 21 thus forms a styli holding carriage, which is adapted to perform translatory movements at right angles to the line of dots which the device is capable of printing, the carriage being pivotable about the bar 37.

The partial view of FIG. 6 shows a variation of an embodiment of the invention, in which the levers are rigid and elastic resetting means of the electro-magnets act on said levers, for example coil springs.

The electro-magnets are circular arranged in a cage 41 as described above. The cage 41 is closed by a lid 42, having a passage 43 for the printing styli. The latter are formed by bent-over rods 44, which are fixed, for example by electric welding at 49, to levers 45, formed by rigid flat strips pivotable on shafts 46. The cage 41 is provided with gaps 47 for passing the levers 45. The pushing members 48 of the electro-magnets act upon a point of the levers located between the welding point 49 and the shaft 46. The point of co-operation between the pushing members and the levers is preferably chosen at substantially equal distances from the printing styli and the supporting point of each lever. In this case the effective travel of an electro-magnet is equal to half that of the stylus and the striking rate of the device may be increased in the same proportion as compared with a device in which the travel of an electromagnet is equal to that of the stylus actuated thereby. A spring 50 acting against the pushing member 48 urges each lever against its pushing member and maintains each electro-magnet at the stop in the rest position. The spring 50 may be a coil spring as shown in FIG. 6, but it may alternatively be formed by a leaf spring or any other kind of spring.

A printing device in accordance with the invention intended to print lines of seven dots spaced apart by 0.4 mm by means of styli of a diameter of 0.3 mm to form characters of a height of 2.5 mms is completely arranged in a cylinder of a diameter of 35 mms and a total length of 45 mms. The track corresponding to the movement of a stylus is 0.4 to 0.7 mm according to the printing surface technique and the track of the corresponding electro-magnet is 0.2 to 0.35 mm. Under these conditions a pulse of overall duration of less than 0.8 msec is necessary to obtain a sufficient printing contrast. If the minimum time interval between two pulses can be reduced to 0.4 msec, for example, which permits the use of given moving techniques of the printing carriage, the resultant rate is of the order of characters per second.

In the various embodiments described above the cage may be made either of non-magnet material, there being provided as many cells as there are electromagnets to be held in each of them, or from a material having satisfactory magnetic permeability, the cage itself forming part of the magnetic circuits of the various electro-magnets held therein.

In order to print characters and lines of characters the device according to the invention may, as usual, be mounted on a carriage adapted to perform a translatory movement and, if desired, is tilted.

In a further mounting method the cage itself forms said carriage, which is provided with the required guiding means.

What is claimed is:

1. A device for printing dots selected from a series arranged in a line, comprising a plurality of separately energizable elongated electro-magnets having parallel longitudinal axes arranged in a circle, a cylindrical enclosure surrounding the plurality of electro-magnets, each electro-magnet having an axial movable core, a plurality of L-shaped printing levers substantially radially arranged within the enclosure, each printing lever having one end attached to the enclosure and having an opposite end arranged within a line formed by said opposite ends, and a plurality of pushing members at tached to the cores of the electro-magnets, each pushing member aligned with a corresponding printing lever, the printing levers exerting a biasing force on the pushing members in a direction corresponding to the rest position of the cores, said levers being formed by tongues punched from an elastic, flat disc fixed to the periphery of said cylindrical enclosure and pointing inwardly into the cylindrical enclosure, the end of each tongue being provided with a printing stylus.

$232? UNHTED STATES PATENT OFFICE CERTIFICATE OF CORRECTION,

Rqtent No. 38%8719 Dated ovember 19, 1974 Inventor(s) Lucien Milan It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Under the Abstract, line 2, "a from a" should read a set of Signed and sealed this 18th day-of February 1975.

(SEAL) Attest:

c. MARSHALL DANN RUTH c. MASON- Arresting Officer Commissioner of Patents and Trademarks

Claims

1. A device for printing dots selected from a series arranged in a line, comprising a plurality of separately energizable elongated electro-magnets having parallel longitudinal axes arranged in a circle, a cylindrical enclosure surrounding the plurality of electro-magnets, each electro-magnet having an axial movable core, a plurality of L-shaped printing levers substantially radially arranged within the enclosure, each printing lever having one end attached to the enclosure and having an opposite end arranged within a line formed by said opposite ends, and a plurality of pushing members attached to the cores of the electro-magnets, each pushing member aligned with a corresponding printing lever, the printing levers exerting a biasing force on the pushing members in a direction corresponding to the rest position of the cores, said levers being formed by tongues punched from an elastic, flat disc fixed to the periphery of said cylindrical enclosure and pointing inwardly into the cylindrical enclosure, the end of each tongue being provided with a printing stylus.