MOSAIC PRINTING HEAD AND DEVICE FOR PRODUCING THE SAME
United States Patent 3584575
A printing head for raster or mosaic-type printing is composed of a block and a mouthpiece; both consisting of synthetic plastic, which are joined with each other. The block and mouthpiece guide individual printing wires along their entire length up to the exit plane of the mouthpiece. The spreading of the wires at the block side remote from the mouthpiece corresponds to the diameter of the respective electromagnetic drives used for operating the wires. In the mouthpiece the printing wires form with each other respective angles amounting to approximately one-half of the spreading angle obtaining between the driving members and the mouthpiece. The spacing between the printing wires in the exit plane of the mouthpiece is such that the wires touch each other only when they reach the printing plane. The guide channels for the printing wires extend between the electromagnetic drives and the mouthpiece on a curved path corresponding to the free bending line of the printing wires.
US Patent References:
Apparatus for printing characters
Loop - September 1938 - 2129065
Printing character forming wires
Johnson - October 1950 - 2524127
Recording machine with grouped recording elements operable selectively to form data-representations
Rast - June 1954 - 2681614
Selective wire printing machine
Wockenfuss - July 1954 - 2683410
Matrix plate for wire printers
Hendrich et al. - February 1955 - 2702428
Apparatus for printing characters
Loop - September 1938 - 2129065
Printing character forming wires
Johnson - October 1950 - 2524127
Recording machine with grouped recording elements operable selectively to form data-representations
Rast - June 1954 - 2681614
Selective wire printing machine
Wockenfuss - July 1954 - 2683410
Matrix plate for wire printers
Hendrich et al. - February 1955 - 2702428
Application Number:
04/774844
Publication Date:
06/15/1971
Filing Date:
11/12/1968
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
400/124.240, 178/30
International Classes:
B41J2/265; G06K15/10; B41J2/235; G06K15/02; B41J3/10; B41J1/18
Field of Search:
101/93R,93C,109 197/1 178/30,23,31
US Patent References:
Primary Examiner:
Penn, William B.
Claims:
I claim
1. Mosaic printing head comprising printing wires and respective electromagnetic means for driving said wires, a base structure of synthetic plastic with a mouthpiece, guide channels for said respective wires extending through base structure and said mouthpiece and converging in said base structure and in said mouthpiece from a wide mutual spacing to a narrow print-head spacing at the face of said mouthpiece, each of said channels guidingly surrounding one of said respective wires from said mouthpiece face along substantially the entire length of the wire and diverging each into an elongated chamber whose diameter is larger than that of said channel, said electromagnetic means comprising elongated electromagnets located in said respective chambers, the longitudinal axes of said channels in said mouth piece being inclined relative to respective geometric reference lines normal to the mouthpiece face, and the angles between said reference lines and the longitudinal axes of said respective elongated electromagnets being about twice as large as the inclination angles in said mouthpiece.
2. In a printing head according to claim 1, said electromagnetic means comprising for each of said printing wires a conically shaped and magnetizable jacket in one of said respective chambers, a magnetizable core piece stationarily disposed in said jacket and having a central bore traversed by said wire, a magnet coil inwardly adjacent to said jacket, a movable armature in coaxial alignment with said core piece and connected with said wire for longitudinally moving said wire, and a return spring for biasing said armature toward inactive position.
3. In a printing head according to claim 1, said base structure having intermediate conical channel portions in which said guide channels merge with said respective bores, and said base structure having an air gap extending transversely of said guide channels and intersecting them near said intermediate conical channel portions.
1. Mosaic printing head comprising printing wires and respective electromagnetic means for driving said wires, a base structure of synthetic plastic with a mouthpiece, guide channels for said respective wires extending through base structure and said mouthpiece and converging in said base structure and in said mouthpiece from a wide mutual spacing to a narrow print-head spacing at the face of said mouthpiece, each of said channels guidingly surrounding one of said respective wires from said mouthpiece face along substantially the entire length of the wire and diverging each into an elongated chamber whose diameter is larger than that of said channel, said electromagnetic means comprising elongated electromagnets located in said respective chambers, the longitudinal axes of said channels in said mouth piece being inclined relative to respective geometric reference lines normal to the mouthpiece face, and the angles between said reference lines and the longitudinal axes of said respective elongated electromagnets being about twice as large as the inclination angles in said mouthpiece.
2. In a printing head according to claim 1, said electromagnetic means comprising for each of said printing wires a conically shaped and magnetizable jacket in one of said respective chambers, a magnetizable core piece stationarily disposed in said jacket and having a central bore traversed by said wire, a magnet coil inwardly adjacent to said jacket, a movable armature in coaxial alignment with said core piece and connected with said wire for longitudinally moving said wire, and a return spring for biasing said armature toward inactive position.
3. In a printing head according to claim 1, said base structure having intermediate conical channel portions in which said guide channels merge with said respective bores, and said base structure having an air gap extending transversely of said guide channels and intersecting them near said intermediate conical channel portions.
Description:
The invention relates to a writing or printing mechanism of the type generally called "mosaic printing head."
There are known mechanisms capable of producing printed characters as a composition of individual character elements, particularly also of mosaic points. It is further known to compose the characters by a raster of 7 times 5 character elements, the characters being produced by a bunch of 7 times 5 printing wires individually actuated by magnetic operation and moved against the medium to be imprinted, using an interposed ink carrier German Pat. Nos. 126,847 and 1,135,928).
Compared with conventional printing devices, mosaic printing heads have the advantage of requiring a very slight amount of space. Therefore, it has been long since attempted to use them to a larger extent as printing component in business machines or in other equipment where space is at a premium, or also for attaining high printing speeds. That prior to this invention, such mosaic heads have not met with general use in practice, has been due to grave disadvantages heretofore preventing their extensive application. In so far as these devices possess a mechanical drive common to all printing wires as well as a selective control of the individual printing wires, such control being capable of establishing or eliminating the positive connection between the printing wires and the common driving member, the devices are awkward in design and, due to the large number of mechanical control members which corresponds to the number of the characters to be printed, they are complicated and hence susceptible to trouble.
In contrast thereto, printing heads in which the individual printing wires are moved by respective electromagnetic drives, have the advantage of a simple and synoptic as well as space saving design. However, printing heads of this type require a very large amount of spreading between the printing plane, in which the printing wires for forming the characters must be as close as possible to each other, and the plane of the driving members which, for producing the required driving force as well as for economical reasons, cannot be smaller than a certain limit.
The devices of this type as heretofore known are characterized by the fact that they guide the printing wires between the driving members and a mouthpiece on a free curved guide path through the air, the free curved path being restrained at most by a few perforated plates having very large guide holes. Furthermore, the known devices of this type possess mouthpieces having a rectangular cutout corresponding to the size of the printing characters, the printing wires being guided in this cutout while in frictional engagement with each other along parallel axes.
The invention described in the following has for its object to [avoid the above-described disadvantages and, moreover,] to devise [a] an improved printing head which can be produced at [a slight economical expenditure] lower cost. The printing head is intended particularly as an additional printer head for such business machines as are equipped with number printing mechanisms, mainly accounting machines.
This is achieved by having the printing head consist of a block of synthetic plastic with a mouthpiece, which guides the printing wires and surrounds them along their entire length up to the exit, the spreading of the wires on the block side that faces away from the printing locality being in accordance with the diameter of the electromagnetic drives. The printing wires are guided in the mouthpiece on a straight path and form with each other respective angles that correspond approximately to one-half of the spreading angle formed between the driving members and the mouthpiece. The spacing between the printing wires in the exit plane of the mouthpiece is such that the wires touch each other only when reaching the printing plane. The guiding channels of the printing wires between the electromagnetic drives and the mouthpiece have a course exactly corresponding to the free bending line of the printing wires.
According to another principle of the invention, the electromagnetic drive of a printing wire consists of a conically shaped, magnetically conducting jacket with an inserted magnetically conducting and solid core having a through bore, and a movable armature lying in the axis of this core and connected with the printing wire. The drive further comprises a conically wound coil and a conically wound spring for effecting withdrawal of the armature. It is preferable to provide for a pressure relief communication with the ambient air for the air compression produced by the armature movement.
FIG. 1 shows on an enlarged scale a vertical section through the printing head according to the invention without printing wires and their driving members.
FIG. 2 is a section along the line II in FIG. 1.
FIG. 3 shows schematically the arrangement of a drive on a still larger scale than that of FIGS. 1 and 2.
FIG. 4 shows the drive with printing wire on a scale further increased in comparison with FIG. 3.
FIG. 5 is a schematic side elevation of a casting mold for producing a mosaic printing head.
FIG. 6 is a plan view of a casting mold according to FIG. 5.
Schematically shown in FIG. 1 is a section through the guiding structure of a mosaic printing head according to the invention for 35 wires. The printing head consists of a base structure 1 and a mouthpiece 2 which are firmly joined with each other by the manufacturing method described hereinafter. The base structure 1 possesses chambers on its side facing away from the printing locality. In the illustrated example there are 35 chambers for receiving respective electromagnetic drives, one for each printing wire. Each chamber 3 merges through a semispherical taper with a core guide 4 in order to receive the armature of the electromagnetic drive during armature movements. Guide channels 6 for the printing wires communicate with the core guides through conical intermediate portions 5 and extend up to the mouthpiece 2. An air gap 7 extends through the base structure 1 at a slight distance from the points where the printing wires join the core guides, the extent of the gap 7 being more clearly apparent from FIG. 2 where, for more clearly showing the raster of the printing character, the junctions of the guide channels, having in reality at this point a diameter of 0.5 mm., are shown exaggeratedly large even in comparison with the enlarged scale of FIG. 2.
The spreading of the printing wires on the side remote from the mouthpiece 2 depends upon the size of the electromagnetic drives. According to the invention, the positioning of the channels 6 in the mouthpiece 2 corresponding to this amount of spreading and measured in angular degrees, is made approximately equal to one-half the spreading of the chamber 3, likewise measured in angular degrees. The guide channels 6 surround the printing wires on their entire length up to their emergence out of the mouthpiece 2. The mutual spacing of the channels 6 in the exit plane is so chosen that the printing wires will just touch each other in the printing plane 8.
The mutual position of the chambers 3 with their core guides 4 and the position of the airgap 7 in the base structure 1 are so chosen that the air gap intersects with all of the guide channels 6 merging with the respective core guides. Since the gap 7 is open toward the environment, the movement of the armature when producing the printing character will not cause excessive pressures in the core guides.
FIG. 3 shows schematically and in straightened fashion the cross-sectional design of a guide channel 6. The chamber 3 serving to accommodate a coil with a housing as a driving element, as will be described hereinbelow, communicates through a tapering portion with the core guide 4. The main channel 9 opens into the guide 4 through a conical intermediate portion 5. In the main channel 9, the printing wire is to have only slight clearance which will not permit lateral folding. A conically shaped transitional channel portion 10 connects the main channel 9 ultimately with the precise guide 11 in the mouthpiece 2. The channel portion 10 forms a gradual transition from the small diameter of the guide channel 11 in the mouthpiece to the wider diameter of the channel 9 in the main portion of the base structure 1. The diameter of the channels 11 are made as small as just needed for guidance of the printing wires, while the diameter of the channel 9 is preferably somewhat wider in order to lower the friction resistance to the movement of the wires. It is preferable to use a synthetic plastic of good gliding abilities for producing the mouthpiece 2 as well as the base structure 1 so that the synthetic material will not impede the movement of the printing wires. For lucidity of illustration, the printing wire and the electromagnetic drive are not shown in FIG. 3. These components are schematically shown in FIG. 4, likewise in straightened fashion and greatly enlarged.
In FIG. 4 the electromagnetic drive is generally denoted by 12 and the printing wire connected therewith is denoted by 13. The electromagnetic drive possesses a jacket 14 made of a magnetic material which, when casting the base structure, becomes firmly seated in the chamber 3 and which then also serves as a mold-core body. On its inner side, the jacket 14 is supplemented by a core piece 15 which has a bore 16 for the passage of the printing wire 13. The core piece 15 has a shoulder 17 for receiving a guide tube 18 made of nonmagnetic material. The armature 19 is movable in this tube and is firmly connected with the printing wire 13 which has a uniform diameter on its entire length. A magnet coil 20 coaxially surrounds the rear portion of the core piece 15 with the guide tube 18 and is seated in the jacket 14. The electrical leads 21 of coil 20 pass through a channel 22 in the base structure 1. The coil is covered by a cover plate 23 traversed by the armature 19. At its outermost end the armature possesses a groove engaged by the narrowest turn of a conical spring 24 which presses against the cover plate 23. The entire arrangement is closed by a cover cap or disc 25 clampingly fastened to the outer rim of the chamber 3.
The base structure may be produced in a mold whose essential components are illustrated in FIGS. 5 and 6 from which the working operations described presently will be apparent.
First, a slider 27 is put upon the base plate 26 of the mold to produce the air channel 7 of the printing head. The slider contains a series of cylindrical but slantingly extending bores which, as to position and diameter, correspond to the subsequently resulting guide channels 6 of the printing head. The rear wall 28 of the mold corresponds as to dimensions and shape to the spherical rear face of the printing head to be produced. The wall has a number of bores corresponding to the number of the chambers 3, into which bores the core pins 29 are to be inserted. A filler body 30 is then placed upon each of these core pins. The filler body 30 has a shape which corresponds to that of the chamber 3 but is smaller than the latter. Subsequently, the jacket 14 according to FIG. 4 is placed upon each of these filler bodies. Ultimately the rear wall 28 with the parts 29 and 30 is placed upon the base plate 26. Now the forming wires 31 which, in accordance with the channel 6 of FIG. 3, are conically arranged, are passed through the bores of the respective core pins 29, the tips of the wires 31 being struck into the mouthpiece 2 previously prepared. By attaching the lateral walls 32 and the other, not illustrated, boundary walls of the mold, the mouthpiece 2 is positively held and fixed in the proper position. The mold is thus prepared for the casting operation.
The described design of the printing head and the mold used for the production of the same are applicable to similar printing heads for mosaic printing.
Hence, the invention is not limited to a printing head with a raster of 5 times 7 points, but can also be employed in the same manner for smaller and larger rasters, for example also for line-shaped or column-shaped rasters.
There are known mechanisms capable of producing printed characters as a composition of individual character elements, particularly also of mosaic points. It is further known to compose the characters by a raster of 7 times 5 character elements, the characters being produced by a bunch of 7 times 5 printing wires individually actuated by magnetic operation and moved against the medium to be imprinted, using an interposed ink carrier German Pat. Nos. 126,847 and 1,135,928).
Compared with conventional printing devices, mosaic printing heads have the advantage of requiring a very slight amount of space. Therefore, it has been long since attempted to use them to a larger extent as printing component in business machines or in other equipment where space is at a premium, or also for attaining high printing speeds. That prior to this invention, such mosaic heads have not met with general use in practice, has been due to grave disadvantages heretofore preventing their extensive application. In so far as these devices possess a mechanical drive common to all printing wires as well as a selective control of the individual printing wires, such control being capable of establishing or eliminating the positive connection between the printing wires and the common driving member, the devices are awkward in design and, due to the large number of mechanical control members which corresponds to the number of the characters to be printed, they are complicated and hence susceptible to trouble.
In contrast thereto, printing heads in which the individual printing wires are moved by respective electromagnetic drives, have the advantage of a simple and synoptic as well as space saving design. However, printing heads of this type require a very large amount of spreading between the printing plane, in which the printing wires for forming the characters must be as close as possible to each other, and the plane of the driving members which, for producing the required driving force as well as for economical reasons, cannot be smaller than a certain limit.
The devices of this type as heretofore known are characterized by the fact that they guide the printing wires between the driving members and a mouthpiece on a free curved guide path through the air, the free curved path being restrained at most by a few perforated plates having very large guide holes. Furthermore, the known devices of this type possess mouthpieces having a rectangular cutout corresponding to the size of the printing characters, the printing wires being guided in this cutout while in frictional engagement with each other along parallel axes.
The invention described in the following has for its object to [avoid the above-described disadvantages and, moreover,] to devise [a] an improved printing head which can be produced at [a slight economical expenditure] lower cost. The printing head is intended particularly as an additional printer head for such business machines as are equipped with number printing mechanisms, mainly accounting machines.
This is achieved by having the printing head consist of a block of synthetic plastic with a mouthpiece, which guides the printing wires and surrounds them along their entire length up to the exit, the spreading of the wires on the block side that faces away from the printing locality being in accordance with the diameter of the electromagnetic drives. The printing wires are guided in the mouthpiece on a straight path and form with each other respective angles that correspond approximately to one-half of the spreading angle formed between the driving members and the mouthpiece. The spacing between the printing wires in the exit plane of the mouthpiece is such that the wires touch each other only when reaching the printing plane. The guiding channels of the printing wires between the electromagnetic drives and the mouthpiece have a course exactly corresponding to the free bending line of the printing wires.
According to another principle of the invention, the electromagnetic drive of a printing wire consists of a conically shaped, magnetically conducting jacket with an inserted magnetically conducting and solid core having a through bore, and a movable armature lying in the axis of this core and connected with the printing wire. The drive further comprises a conically wound coil and a conically wound spring for effecting withdrawal of the armature. It is preferable to provide for a pressure relief communication with the ambient air for the air compression produced by the armature movement.
FIG. 1 shows on an enlarged scale a vertical section through the printing head according to the invention without printing wires and their driving members.
FIG. 2 is a section along the line II in FIG. 1.
FIG. 3 shows schematically the arrangement of a drive on a still larger scale than that of FIGS. 1 and 2.
FIG. 4 shows the drive with printing wire on a scale further increased in comparison with FIG. 3.
FIG. 5 is a schematic side elevation of a casting mold for producing a mosaic printing head.
FIG. 6 is a plan view of a casting mold according to FIG. 5.
Schematically shown in FIG. 1 is a section through the guiding structure of a mosaic printing head according to the invention for 35 wires. The printing head consists of a base structure 1 and a mouthpiece 2 which are firmly joined with each other by the manufacturing method described hereinafter. The base structure 1 possesses chambers on its side facing away from the printing locality. In the illustrated example there are 35 chambers for receiving respective electromagnetic drives, one for each printing wire. Each chamber 3 merges through a semispherical taper with a core guide 4 in order to receive the armature of the electromagnetic drive during armature movements. Guide channels 6 for the printing wires communicate with the core guides through conical intermediate portions 5 and extend up to the mouthpiece 2. An air gap 7 extends through the base structure 1 at a slight distance from the points where the printing wires join the core guides, the extent of the gap 7 being more clearly apparent from FIG. 2 where, for more clearly showing the raster of the printing character, the junctions of the guide channels, having in reality at this point a diameter of 0.5 mm., are shown exaggeratedly large even in comparison with the enlarged scale of FIG. 2.
The spreading of the printing wires on the side remote from the mouthpiece 2 depends upon the size of the electromagnetic drives. According to the invention, the positioning of the channels 6 in the mouthpiece 2 corresponding to this amount of spreading and measured in angular degrees, is made approximately equal to one-half the spreading of the chamber 3, likewise measured in angular degrees. The guide channels 6 surround the printing wires on their entire length up to their emergence out of the mouthpiece 2. The mutual spacing of the channels 6 in the exit plane is so chosen that the printing wires will just touch each other in the printing plane 8.
The mutual position of the chambers 3 with their core guides 4 and the position of the airgap 7 in the base structure 1 are so chosen that the air gap intersects with all of the guide channels 6 merging with the respective core guides. Since the gap 7 is open toward the environment, the movement of the armature when producing the printing character will not cause excessive pressures in the core guides.
FIG. 3 shows schematically and in straightened fashion the cross-sectional design of a guide channel 6. The chamber 3 serving to accommodate a coil with a housing as a driving element, as will be described hereinbelow, communicates through a tapering portion with the core guide 4. The main channel 9 opens into the guide 4 through a conical intermediate portion 5. In the main channel 9, the printing wire is to have only slight clearance which will not permit lateral folding. A conically shaped transitional channel portion 10 connects the main channel 9 ultimately with the precise guide 11 in the mouthpiece 2. The channel portion 10 forms a gradual transition from the small diameter of the guide channel 11 in the mouthpiece to the wider diameter of the channel 9 in the main portion of the base structure 1. The diameter of the channels 11 are made as small as just needed for guidance of the printing wires, while the diameter of the channel 9 is preferably somewhat wider in order to lower the friction resistance to the movement of the wires. It is preferable to use a synthetic plastic of good gliding abilities for producing the mouthpiece 2 as well as the base structure 1 so that the synthetic material will not impede the movement of the printing wires. For lucidity of illustration, the printing wire and the electromagnetic drive are not shown in FIG. 3. These components are schematically shown in FIG. 4, likewise in straightened fashion and greatly enlarged.
In FIG. 4 the electromagnetic drive is generally denoted by 12 and the printing wire connected therewith is denoted by 13. The electromagnetic drive possesses a jacket 14 made of a magnetic material which, when casting the base structure, becomes firmly seated in the chamber 3 and which then also serves as a mold-core body. On its inner side, the jacket 14 is supplemented by a core piece 15 which has a bore 16 for the passage of the printing wire 13. The core piece 15 has a shoulder 17 for receiving a guide tube 18 made of nonmagnetic material. The armature 19 is movable in this tube and is firmly connected with the printing wire 13 which has a uniform diameter on its entire length. A magnet coil 20 coaxially surrounds the rear portion of the core piece 15 with the guide tube 18 and is seated in the jacket 14. The electrical leads 21 of coil 20 pass through a channel 22 in the base structure 1. The coil is covered by a cover plate 23 traversed by the armature 19. At its outermost end the armature possesses a groove engaged by the narrowest turn of a conical spring 24 which presses against the cover plate 23. The entire arrangement is closed by a cover cap or disc 25 clampingly fastened to the outer rim of the chamber 3.
The base structure may be produced in a mold whose essential components are illustrated in FIGS. 5 and 6 from which the working operations described presently will be apparent.
First, a slider 27 is put upon the base plate 26 of the mold to produce the air channel 7 of the printing head. The slider contains a series of cylindrical but slantingly extending bores which, as to position and diameter, correspond to the subsequently resulting guide channels 6 of the printing head. The rear wall 28 of the mold corresponds as to dimensions and shape to the spherical rear face of the printing head to be produced. The wall has a number of bores corresponding to the number of the chambers 3, into which bores the core pins 29 are to be inserted. A filler body 30 is then placed upon each of these core pins. The filler body 30 has a shape which corresponds to that of the chamber 3 but is smaller than the latter. Subsequently, the jacket 14 according to FIG. 4 is placed upon each of these filler bodies. Ultimately the rear wall 28 with the parts 29 and 30 is placed upon the base plate 26. Now the forming wires 31 which, in accordance with the channel 6 of FIG. 3, are conically arranged, are passed through the bores of the respective core pins 29, the tips of the wires 31 being struck into the mouthpiece 2 previously prepared. By attaching the lateral walls 32 and the other, not illustrated, boundary walls of the mold, the mouthpiece 2 is positively held and fixed in the proper position. The mold is thus prepared for the casting operation.
The described design of the printing head and the mold used for the production of the same are applicable to similar printing heads for mosaic printing.
Hence, the invention is not limited to a printing head with a raster of 5 times 7 points, but can also be employed in the same manner for smaller and larger rasters, for example also for line-shaped or column-shaped rasters.