US3419752A

US3419752A - Multiple spark printer

Info

Publication number: US3419752A
Application number: US486448A
Authority: US
Inventors: Schmidt Siegfried
Original assignee: US Philips Corp
Current assignee: US Philips Corp; North American Philips Co Inc
Priority date: 1964-09-11
Filing date: 1965-09-10
Publication date: 1968-12-31
Anticipated expiration: 1985-12-31
Also published as: BE669417A; CH436794A; DE1294488B; AT256523B; NL6511676A; GB1118616A

Description

Dec. 31, 19 8 s. SCHMIDT 3,419,752

IULTIPLE SPARK PRINTER Filed Sept. 10, 1965 Sheet of s INVENTOR. v

' SIEGERIE'D SCHMIDT BY M (I AGENT Sheet 2 of 5 S. SCHMIDT MULTIPLE SPARK PRINTER Dec. 31, 1968 Filed Sept. 10, 1965 INVENTOR. SIEGFRIED SCHMIDT AGEN F lG.2

1968 s. SCHMIDT I 3,419,752

MULTIPLE SPARK PRINTER Filed Sept. 10, 1965 Sheet 3 of 3 -153 INVENTOR SIEGFRIED SCHMIDT United States Patent 3,419,752 MULTIPLE SPARK PRINTER Siegfried Schmidt, Hamburg, Germany, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Sept. 10, 1965, Ser. No. 486,448 Claims priority, applicatig sl figrmany, Sept. 11, 1964,

i 7 Claims. (Cl. 315-35) In high speed printers and tape-punching machines utilizing electric spark generated shockwaves the individual spark gaps have to be arranged close to one another. In such a tape-punching machine one spark gap is re quired for each of the usually five to eight parallel code hole tracks. The spacing between the said tracks is usually approximately 2.5 mm. and the spark gaps must therefore also be spaced apart the same distance. In a highspeed printer utilizing spark generated shoc-k waves one spark gap is provided for each character printing area of a line. In this machine the spacing between the spark gaps is equal to the width of a character printing area, for example, from 2.5 mm. to 4 mm. To obtain a service able output the inductance in a spark discharge circuit must be as low as possible. Thus two important requirements are imposed upon such a group of spark gaps: small distance between the gaps and low inductances of the supply conductors. A further requirement is that the heat produced can be dissipated satisfactorily.

An object of the invention is to provide a device having a group of spark gaps which fulfills the above requirements due to the complete discharge circuit comprising the spark gaps, the discharge capacitors and the supply leads forming a unit.

It is known to build together a spark gap, discharge capacitor and supply conductors for producing electric sparks for lighting purposes. This known, however, comprises only a single spark gap of coaxial form. Such a coaxial form is unsuitable, however, for arranging a plurality of spark gaps close to one another since, with the comparatively small diameters than to be utilized, the necessary capacitance requires a great length of the coaxial capacitor (cylindrical capacitor). Furthermore an aperture must be provided through which the pressure wave 'which is building up cylindrically about the axis of the spark impinges substantially directly on the object (paper and matrice or character). This is difficult to realise with a coaxial form of the spark gap.

According to the invention in a device having closely adjacent spark gaps constituted by spark electrodes and separate igniting electrodes by the use of a block consisting of alternately dielectric layers and metal layers, the individual metal layers in each case constituting alternately the supply conductor to one spar-k electrode, which also serves as a capacitor electrode, and a further capacitor electrode Which is directly connected to the other spark electrode of the spark gap.

In stacking, the sequence of the layers and plates is thus as follows: supply conductor to one electrode, insulation, supply conductor to the other electrode, insulation, etc. Preferably, the dielectric material used for the required insulating plates is such that the capacitance bridging a spark gap suffices for the capacitor to act as a supply capacitor for the electric spark. These capacitors, referred to as discharge capacitors, are comparatively cheap to manufacture for the envisaged purpose.

In order that the invention may be readily carried into effect, two embodiments thereof will now be described in detail, by way of example, with reference to the accompanying drawings.

FIG 1 is a perspective view of one embodiment of a 3,419,752 Patented Dec. 31, 1968 multi-electric spark discharge block of a high speed printer according to the invention.

FIG. 2 is a diagrammatic view of the circuit of the discharge block according to the invention.

FIG. 3 is another perspective view of a different embodiment of a discharge block according to the invention.

An assembly according to the invention comprises a plurality of spark gaps including electrodes, supply conductors and capacitors, which assembly is referred to hereinafter as the discharge block. A simple embodiment of a discharge block is the open structure shown in FIG. 1. In this embodiment, for example, n spark gaps (only three are shown) are defined by each pair of spar-k electrodes A K Az-Kg, etc. to A K Each spark gap defining a pair of electrodes having associate therewith an igniting electrode Z Z etc. to Z The electrodes A to A all of which have the same potential, are placed in a copper block 1 which represents the point 0 in the circuit diagram shown in FIG. 2. The opposing spark electrodes K to K are soldered to

copper plates

2, 2", etc., which serve as supply conductors and also as large area contacts with one of the capacitor electrodes, C l, C l, etc., said copper plates 2 being connected to points 0 to c respectively in the circuit diagram of FIG. 2. the electrodes A to A are arranged opposite to the electrodes K to K An insulating strip and spacer 3 separates the copper plates 2', 2", etc., from the copper block 1 and provides the necessary and proper spacing between the electrodes A and K. The igniting electrodes Z to Z are fixed in bores in the strip 3.

Between each two

adjacent copper plates

2, 2", etc., connected to the spark electrodes K and K for example plates 2" and 2, there are arranged two dielectric plates 4, 4' for example ceramic plates, which are separated by a further copper plate 5. All the copper plates 5 are connected to the copper block 1, as may be seen from the

copper plates

5 and 5" (which is broken away). :Each of the plates 5 forms a large area contact with the other electrode of one of the capacitors C C to C C and a supply conductor to one of the electrodes A to A (FIG. 2).

The capacitor electrodes 5 themselves are metal layers provided in the usual manner on the dielectric plates 4, which metal layers must not extend, at least on the upper side in FIG. 1, as far as the edges of the plates 4 in order to obtain adequate insulation. To ensure good passage of the spark current it is advantageous to solder the said metal layers 5 to the copper block 1. The plates 5 are made as thin as possible to permit a substantial number to be used for storage of dielectric charge.

The stack comprising the plurality of

copper plates

2 and 5 and the dielectric plates 4 in each case begins and terminates with a plate 5. Thus two capacitors, each separated by a dielectric plate, are connected in parallel with each spark gap. So the volume of two dielectric stored plates is available as the dielectric charge volume for each spark gap.

The maximum storage of electrical energy is obtained if the dielectric is charged to its maximum permissible field strength. For all the capacitors of the discharge block the length of the spark gaps and the distances from spark gap to spar-k gap are predetermined. Thus the maximum operating voltage and the maximum operating field strength are also determined. The material for the dielectric plates '4 is chosen as a function of the maximum operating field strength. To obtain optimum conditions it may sometimes be useful to employ different dielectrics. With discharge blocks intended for strip-punching machines and high speed printers the operating field strength occurring is usually comparatively low. Ceramic material having a high dielectric constant is therefore especially suitable for the dielectric plates.

The complete discharge block consisting of capacitors C l, C l to C n, C n is resiliently clamped together for absorbing electrostrictive variations in thickness of the dielectric plates which occur under certain conditions. For this purpose, clamping bolts 7 are passed through the bores in terminal plates 6 and press on these terminal plates from the outside with the interposition of suitable springs (not shown). Since the location of the desired action of the gaps A, K is determined during punching by the position of the punching matrices and during printing by the positions of the characters the very small shifts of the spark gaps caused by a possible electrostriction are not troublesome.

A second embodiment, shown in FIG. 3, is especially suitable for higher powers. In this embodiment the complete discharge block consisting of a plurality of capacitors is incorporated in a metal holder "8 closed on all sides and filled with oil. The necessary insulating distances with respect to the open structure FIG. 1, are thus smaller. The dissipation of heat becomes very favorable and may still be improved by providing cooling fins on the holder 8 or, more efiectively still, by circulation of the oil from holder 8 through a cooler. The embodiment shown in FIG. 3 has 8 spark gaps, such as may be used, for example, for a machine for punching code holes in tape. 'In this case the spark gaps are formed, as surface-spark gaps. A copper block 9 to which the electrodes A are soldered constitutes part of the wall of the holder 8. An insulator 10 is provided in the wall of the holder 8 also to allow the passage of the electrodes K and the igniting electrodes Z. Material especially suitable for the insulator is ceramic material, which can be soldered to the holder, for example of copper, in a liquid-tight manner and 'with good thermal contact.

The circuit of the embodiment shown in FIG. 3 is the same as that shown in FIG. 2 for the discharge block of open structure shown in FIG. 1. The connections of the igniting electrodes Z and the connections made to the plates 2 are led to the exterior, for example, through ceramic lead-through devices 11 and 12 respectively which have been closed by soldering. The connection 0 is the housing '8 itself. Side plates 13 merely serve for mounting of the device.

What is claimed is:

1. A multiple spark printer comprising means defining a plurality of spark gaps, each said spark gap including a pair of spark electrodes in spaced opposed relation, capacitor means coupled with each said pair of spark electrodes; said capacitor means comprising a first capacitor electrode sandwiched between a pair of dielectric members, said first capacitor electrode being connected with one said spark electrode, and a second capacitor electrode on each said dielectric member remote from said first capacitor electrode, said second capacitor elctrode being connected with the other of said spank electrodes, and lead-in conductor means coupled with said capacitor electrodes.

2. A multiple spark printer according to claim 1 wherein said first and second capacitor electrodes comprise thin films of conductive material attached to said dielectric members.

3. A multiple spark printer according to claim 2 wherein said capacitor means coupled with each said pair of electrodes have different dielectric values.

4. A multiple spark printer according to claim 2 with the addition of means for resiliently clamping together said capacitor means for each said spark gap.

5. A multiple spark printer according to claim 1 wherein said means defining a plurality of spark gaps cornprises, a bar of conductive material having a plurality of spark electrodes projecting therefrom in the same direction in spaced parallel relation, said bar being connected with one of said first and second capacitor electrodes, and an insulator-spacer member extending parallel with said pro jecting spark electrodes for separating said bar from said capacitor means and the associated spark electrodes thereof, one said lead-in conductor means being coupled with said bar.

6. A multiple spark printer according to claim 1 with the addition of housing means of conductive material euclosing said capacitor means coupled with one of said first and second capacitor electrodes.

7. A multiple spark printer according to claim 6 wherein said means defining a plurality of spark gaps comprises said housing means; said housing means having a wall member including a first plurality of surface electrodes integral therewith and connected through said housing means with one said lead-in conductor, an insulator means in said wall member adjacent said surface electrodes, and a second plurality of surface electrodes in said insulator means in spaced opposed relation with said first plurality of electrodes, and means for connecting the other of said first and second capacitor electrodes.

References Cited UNITED STATES PATENTS 1,683,590 9/1928 Atherton 313-268 X 2,618,765 11/1952 Vogelsanger 313---268 X JOHN W. HUCKERT, Primary Examiner.

R. F. POLISSACK, Assistant Examiner.

U.S. Cl. X.R.

Claims

1. A MULTIPLE SPARK PRINTER COMPRISING MEANS DEFINING A PLURALITY OF SPARK GAPS, EACH SAID SPARK GAP INCLUDING A PAIR OF SPARK ELECTRODES IN SPACED OPPOSED RELATION, CAPACITOR MEANS COUPLED WITH EACH SAID PAIR OF SPARK ELECTRODES; SAID CAPACITOR MEANS COMPRISING A FIRST CAPACITOR ELECTRODE SANDWICHED BETWEEN A PAIR OF DIELECTRIC MEMBERS, SAID FIRST CAPACITOR ELECTRODE BEING CONNECTED WITH ONE SAID SPARK ELECTRODE, AND A SECOND CAPACITOR ELECTRODE ON EACH SAID DIELECTRIC MEMBER REMOTE FROM SAID FIRST CAPACITOR ELECTRODE, SAID SECOND CAPACITOR ELECTRODE BEING CONNECTED WITH THE OTHER OF SAID SPARK ELECTRODES, AND LEAD-IN CONDUCTOR MEANS COUPLED WITH SAID CAPACITOR ELECTRODES.