CA1038017A - Electrically addressed apertured modulator for electrostatic printing - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Apparatus is described for aperture modulated electrostatic printing. This apparatus comprises a substrate of dielectric material, a continuous electrode disposed on one side of the substrate, a plurality of apertures extending through both the substrate and the continuous electrode, a plurality of closely spaced electrical devices mounted in one or more straight and parallel rows on the substrate, and a plurality of electrically conductive continuous strips fixedly attached to the other side of the substrate. Each strip has a first section attached at one end to one of the electrical devices and extends in a direction generally perpendicular to the row or rows of electrical devices.
Each strip has a second section extending from the first section in a direction generally parallel to said row or rows. The second sections of said strips are more widely center spaced at all points than any of the first sections. Each of the electrical devices comprises an electrode abutting an aperture formed in said sub-strate.

Description

~038q~

The present invention relates to a new and improved system for electrostatic reproduction and more particularly to an impro~ement in modulated aperture non-contact electrostatic printing of the type wherein a stream of charged particles, preferably ions, is modulated by passage through one or more rows of individually addressed apertures containing bipolar electrostatic fringing fields. A receiving medium is translated past the aperture rows and receives the modulated particle stream or additional particles introduced into the modulated stream, for line-at-a-time or line scan printing operations. The present invention is specifically concerned with particle modulator con-structions whereby, ~or enhanced printing resolution and speed, a large number of ~ery small apertures can be clos~ly spaced in one row or in two or more closely spaced rows and ~et pro~ide separate electrical access to individual apertures by means of no~el printed circuit configurations and structures. Th~ present invention is also concerned with novel appaxatus for mounting the particle modulator. The invention is useful in a wide range of applications including document copiers and computer printout devices.
One type of electrostatic printing apparatus for which the present system is intended employs a modulator element designed to support a double layer charge at apertures in the modulator to produce fringing fields of electrical force within the apertures, including blocking fields, for modulating an ion stream in accordance with an imaye to be reproduced. As set forth in commonly assigned Canadian Patent No. 986,172, issued March 23, 1976 and entitled "ELECTROSTATIC PRINTING SYSTEM AND

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METHOD USING IONS AND TO~ER PARTICLES", the present invention may be employed in a system wherein an ink mist is introduced into the path of the modulated ion stream so that the ions impinge upon the ink mist particles causing them to become charged and then accelerated by an applied electrical field toward a print receiving medium. Specially constructed modulator elements for use in systems of this sort are shown in commonly assigned United States Patent No. 3,689,~35 issued September 5, 1972 for "ELECTRO-STATIC LINE PRINTER". The corresponding Canadian Patent No.
982,647 issued January 27, 1976.
A printing apparatus of this type prints an unlimited variety of useful shapes, including alphanumeric characters, is capable of printing at rates far in excess of conventional mechanical printers, and yet operates almost silently.
qlhe qualit~ and resolution of this type of electrostatic printer increases inversely to the size and directly to the spatial density of modulating apertuxes. While, according to the present invention, an electrostatic printer can be con-structed using only a single linear array of apertures, ~o that one horizontal strip of the printed line is printed simultaneously, the use of additional vertically spaced linear arrays displaced horizontally from each other so that apertures in adjacent linear arrays are staggered alIows for more complete coverage of a printed line and, therefore, better resolution. This arrangement also allows a significant increase in the printing speed since several vertically spaced horizontal strips of the printed line can be printed simultaneously and the significance o gate-switching time lags reduced.

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~.o3~0~7 1 Hence, to obtain increased resolution and speed, it is

2 necessary to utilize very small apertures as closely spaced as

3 possible. But since this type of electrostatic printing requires that each aperture be elec~rically controlled individually, an electrical connection must be made to each aperture and the crowd-ing of connections becomes a limiting factor on the number of ; 7 apertures of a given size that can be located in a given area.
8 The apparatus of the present invention comprises a g flexible printed circuit board containing both the modulating apertures and the necessary electrical leads. The leads are Il arranged in a pattern which facilitates electrical connections 12 to the apertures. The patt~rn further allows for a simple method 13 of electricall~ connecting the leads on the ~lexible circuit board to a set of co~ventional prin~d circuit ca$ds with conventional printed circuit card edge connectors. The circuit 16 boards! both conventional and flexible, and the edge connectors, 17 are supported in a configuration that optimizes the number of 18 electrical connections possible, thus optimizing the resolution 191 and speed of an elPctrosta~ic printer utilizing modulators of the 20 ¦ type described.
21¦ One object of the present invention is, therefore, to 22 ~mprove the resolution, and to increase the speed of modulated 23 ¦ aperture electrostatic printers.
24 ¦ An advantage of the present invention is that it allows 25 ¦ for a large number of electrical connections to be made to an 29 apc tured modulator.

33o 321 '. 5 l~ ~
~ 3~ 7 _ ~ Another advantage is that electrical connections to 2 the apertured modulator can be made simply, by ~he use of a 3 conventional printed circuit card edge connectorJ

4 ~hese and other objects, features, and advantages of the present invention will be mor~ readily apparent after readin~
6 the following detailed description with reference to the 7 accompanying drawingswherein:
8 ~igure 1~ is a schematic diagram of a modulated 9 aperture electrostatic particle modulator biased to provide blocking fields;
11 Figure lB is a schematic diagram o a modulated 12 aperture electrostatic particle modulator biased with the biasin~
13 voltages deactivated so that charged particles may pass through;
14 Figure 2 is a ~chematic diagram o~ a mo,dulated aperture electxostatic particle modulator in a system wherein 16 ions are modulated thereby and the modulated ion stream developed ., 17 by impingement into an uncharged ink mist prior to deposit on .
18 the print receiving m~dium;
19 Figure 3 is a fragmentary plan view and Figure 3A a fragmentary side cross-sectional view of a line or bar modulating 21 element for modulated aperture electrostati~ line printing;
22 Figure 4 is a schematic diagram of a modulated aperture 23 electrostatic printing system with ions and an ink mist wherein 24 the aperture is electrically addressed with logic circuitry;
Figure 5 is a schematic diagram of a modulated aperture 26 electrostatic pxinting system with ions and an ink mist wherein 2~ the aperture is electrically addressed.with optically generated 28 electrical signals;
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32 . . , - 6 -. , '.

1C~38~7 Figure 5A is a schema-tic diagram illustrating the system of Figure 5 employed with linear arrays of.segmented ape~tures and pho~oreceptors;
Figure 6 is a fragmentary plan view of the flexible s circuit board. In this figure, it should be noted that the horizontal dimensions are expanded relative to the vertical for better clarity;
Figure 6A is an enlarged fragmentary plan view of the aperture region of the flexible circuit board of Figure 6;
Figure 6B is a fragmentary side view of.Figure 6A taken along lines 6B;
Figure 6C is an enlarged fragmentary plan view of the terminal pad region of Figure 6;
Figure 7 is a fragmentary perspective view of the connection between the conventional printed circuit board edge connector and the 1exible circuit board;
Figure 8 is a perspective view from above of a flexible circuit board of the type shown in Figure6 mounted on a card cage according to the present invention;
Figure 8 is a perspective view from above of a flexible circuit board of the type shown in Figure 6 mounted on a card cage according to the present invention;
Figure 8A i5 a side sectional elevation with portions cut-away of the card cage assembly illustrated in Figure 8;
Figure 8B is a fragmentary sectional view of the interior surface of the card cage wall of card cage illustrated in Figure 8 carrying edge connectors;
Figure 8C is a fragmentary view of the card cage from the side of the card cage from which ~he card apertures are formed;
Figure 9 is a perspective view rom above of an alternative embodiment of a card cage mounting a circuit board according to the present invention.

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1 I. Modul~tcd Aperture Electrostatic Printin~
2 A. General Background:
3 The present art of modulated aperture electrostatic 4 printing has been an outgrowth of the early work in electrostatic screen printing by McFarlane, set forth in commonly assigned 6 U.S. Patent Nos. 3,220,831, 3,220r833, and 3~339r469~
In this early work a screen or other modulator was first 8 prepared with an electrostatic charge corresponding to the Lmage 9 to be reproduced. This imaged modulator was dusted with charged toner particles and then the dusted screen exposed to an overall 11 projection ~ield which attracted the toner particles Erom the 12 modulator across an air gap to paper or other prin~ receiving 13 medium to which it was ~ixed with heat or otherwise. The toner 14 pattern was transferred across the air gap without substantial disruption.
16 Later work, disclosed in commonly assigned U.S. ~atent 1~ Nos. 3,625,604 and 3,645,614, enabled the toner particles to be lR projected directly from the toner source through ~he modulator 19 ~usually a screen) onto the print receiving medium or to a 2~ ~ransfer surface, thus eliminating the step of dusting the 21 modulator. The modulator could also be used to modulate an ion 22 stream~ as disclosed in commonly assigned U.S. Patent No.
23 3,582,206, ~or subsequent development in a variety of ways.
24 Importantly, this kept toner away ~rom the screen and avoided the need for costly and time consuming screen cleaning steps.
26 In addition, the low mass ions required relatively low gating 27 voltages and smaller apertures, by comparison to the larger, 29 heavier toner particles.

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~ ~ ~ .
~L~38~7 1 As disclosed in commonly assigned U.S. Patent No.
2 3~689,935 modulators can ~e designed to accept a stream of 3 electrical signals, such as from a computer, to rapidly vary 4 the charge pattern on the modulator. High speed printing operations, such as are desired in computer printout applications 6 can be carried out with electrically addressed modulators.
7 Electrically addressed modulators, as opposed to optically 8 addressed or xerographically imaged modulators are the type to 9 which the present invention applies.
B. Electrically ~ddressed Paxticle Modulators:
11 ~igures lA and lB illustrate the effect of double layers of 12 charge upon the passage o~ charged particles through an 13 electrically addressed particle modulator lO. The modulator lO
14 has an aperture 14 with first and second conductl~ve layers ll and 12 carried on a thin electrical insulator layer 13. The 16 ¦ ratio of insulator 13 thickness to aperture 14 diameter (T/D
17 ¦ ratio) is less than l.00 and preferably about 0.25. The 18 ¦ conductive layer ll facing the source 15 of charged particles ¦ 16 is biased with opposite polarity from the çharged particles 20 ¦ 16 and the opposed conductive layer 12 is grounded, so that a 21 ¦ double layer of charge is fonmed a~ the aperture 14 creating 22 1 electrostatic lines of force ox fringing fields 17 within the 23 ¦ apsrtures 14 which tend to block the passage charged particles 24 ¦ 16 therethrough, as shown. ~igure lB illustrates how charged 25 ¦ particles 16, under the influence o overall pro~ection field }I
26 ¦ pass through the modulator lO when the modulator bias is removed.
27 ¦ If the charged particles are toner or ~k, they can be deposited 28 di ectly on tXe print recei-ing medium; however, it is preferred 2 I .
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I

38(:1 17 that the charyed particles be gaseous ions. A modulated ion stream is developed in the manner shown in Figure 2.
C. Printing with Ions and A Toner Mist:
Figure 2 illustrates a system for electrostatic printing wherein a steam of ions which has been modulated with an electrically addressed modulator 10 in the manner shown in Figures lA and lB is developed by directing the modulated ion stream into a cloud or mist of uncharged solid toner particles or liquid ink droplets. In Figures lA, lB and 2 corresponding elements are correspondingly numbered. Specifically, Figure 2 shows ions 21 from an ion source, i.e. corona wire 20, being flooded on a particle modulator 10. The segmented upper con-ductor layer lla is charged, establishing fringing fields 17 in the aperture 14a which block ions 21 from passing th~rc-through. By comparison, segment llb o~ the upper conductor is not charged and ~ons 21 pass through the aperture 14b (under the influence of overall projection field H) established between the corona wire 20 and reverse polarity electrode 24 (also reerred to as the "backbar" 24) and impinge upon uncharged particles of ink 22 supplied from uncharged ink mist generator 23. Uncharged ink particles 22 which are struck by the ions 21 become charged and are accelerated by the field H onto the paper 25 interposed therein. Toner particles 27b which are not struck by ions 26 continue laterally to an exhaust duct 28. When liquid ink particles are employed, as is preferred, the system has the important advantage that it prints on ordinary, untreated paper and does so without a ~urther developing step and or an intermediate transfer surface. The foregoing is set forth in 38Q~
greater detail and scope in the aforementioned Canadian Patent No. 986,172, issued March ~3, 1976.
Figures 3- and 3A illustrate an electrically addressable particle modulator wherein the modulating element 30 consists of an elongate length or bar of insulating material 31 with a continuous layer of conducting material 32 on one side and a segmented conductive layer 33 on the other. Segmented conductive layer 33 consists of individual insulatively isolated segments 33a, 33b, 33c, etc. The element 30 is formed with a row o~ apertures therethrough, each aperture surrounded by a conductive segment 33a, 33b, 33c, etc. An electrical lead is provided to the continuous conductive layer 32 for applying a uni~orm potential across one face o~ the insulative la~er 31.
A plurality of electrical leads 34a, 3~b, 3~c, etc., are provided one for each of the conductive segments 33a, 33b, 33c, etc., so that a different potential can be applied to each of the segments for creating selectively different double layers of charge at each of the apertures 35 in accordance with a pattern to be reproduced. A particle modulator constructed in this manner, sometimes referred to as a "line printer", is employed in line-at-a~time printing operations, such as in facsimile printing or computer data printers. In the usual case, the print receiving medium is translated past the particle modulator and ink particles deposited on the medium in line patterns in accordance with selected electrical signals supplied to the se~mented conductors 33a, 33b, 33c.

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- 10380~ 7 Figure 4 is a diagram for a computer printer utilizing the particle modulator 30 illustrated in Fiyures 3 and 3A, with corresponding parts numbered accordingly. Each of the conductive segments 33 is connected by a separate electrical lead 34 through resistance 42 and appropriate logic circuitry 37 to an electrical power supply 44. Continuous conductive coating 32 is connected to a fixed potential or ground 43. As in the preferred system of Figure 2, uncharged ink particles from supply 39 are introduced into a stream of ions emanating 1~ from corona wire 38 after they have been modulated by passage through the modulator aperture 35. Ions impinging upon toner particles become charged and are attracted to the print receiving medium 41 by the backbar electrode 40. The print receiving medium is translated continuously transversely to the ion flow Eor printing.
Electrically addressed systems according to the present invention can also include systems of the type employing modulator and photodetector arrangements as shown in Figure 5 and 5A where a linear array of photodetectors 45 detect an optical image ~t a distance from the modulator 30, transforming linear segments of such image into electrical signals carried to the modulator 30 by a plurality of separate electrical leads 34a, b and c.
According to this arrangement, each of the conductive segments 33 of the segmented conductive layer of particle modulator 30 is connected by an electrical lead 34 through a photoconductor cell .
45 to a ground potential 43 or other fixed potential as herein-after described. At the same time, an electrical power supply is connected by way of lead 46 through resistances 43 to Q
.i, ~10380~7 I . _ ~, I ¦ each of the seyments 34 of the se~m~nted conductive layer.
- 2 ¦ The photoconductor cells 40 can be addressed in any manner 3 ¦ desired, such ~s by sweeping an image continuously across the 4 ¦ row of photoconductor cells or sweeping an image line-by-line ¦ across the row of photoconductor cells.
6 ¦ Thus, it will be seen that while the representative 7 ¦ systems illustrated according to the present invention in Figur~s 8 ¦ 4, 5 and 5A differ in the means employed to generate electrical 9 I addressing signals, they share a common need for individual 10 ¦ electrical connection 34 between a large number o~ small closely 11 ¦ spaced linear oxiented conductive segments 33 and their : 12 ¦ associated electrical aomponents, such as the resistors 42 and 13 ¦ logic circuitry 37 of Figure 4. Accordingly r the present 14 ¦ invention, as set forth in the following desaription, relates 15 I to specific means and techniques for achieving that end.
16 ¦ II. Flexible Circuit Board Particle Modulators Access Patterns I and Assemblies 17 I _ - 18 ¦ A. The FlexibLe Circuit Board:
l9 I Referring now to Figure 6, a flexibl~ circuit board 20 I type of particle modulator is shown generally at 50. The board 21 ¦ 50 is constructed of a ~hin flexible substrate 51 of plastic 22 ¦ sheet, such as a polyimide sheet sold under the registered 23 I Trademark "Kapton", or other suitable ~lexible dielectric or 241 electrically insulating material. A continuous electrically 251 conducting layer 52 is applied to one surface of the substrate 26 51 and a plurality o~ eleatrically isolated conductive seyments 27 53 is applied to the opposite side of substrate 51. Each se~ment ~28 53 terminates at one end in an annular portion 55 surrounding one 32 _ 13 ~
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- ~L0380~7 of the apertures 54. The apertures 54 are arranged in two parallel horizontal rows with the apertures in one row horizont~lly displaced from the apertures in the next row by one-half pitch so that apertures in adjacent rows are staggered.
The segments 53 can be fashioned by cGnventional printed circuit methods and each provides an electrically conductive circuit between one of the modulatiny apertures 54 and one of the contact pads 57. Each seyment 53 is thus continuous and consists of annular portion 55 surrounding an aperture 54, at one end, 10 connected to a terminal contact pad 57 by a thin, line-like (sometimes hereinafter "linear") lead portion 56. Accordingly, each electrical device or current modulating aperture is provided with a separate electrical lead. In the pre Eerr~d arrancJement illustrated in Figure 6, each linear leacl portiorl 56 oE a particular segment consists of a lonyitudinally or vertically extending portion 56a connected to a horizontally or laterally extending portion 56c at a right angle bend or elbow 56b at the distal end of the vertical portion 56a. Some of the vertical lead portions 56a include angled portions 56d as will be more 20 fully explained herein. The horizontal lead portions 56c lie generally parallel to the rows of apertures 54, whereas the vertical lead portions 56a lie generally perpendicular thereto.
- The elbows 56b of the linear lead portions 56 are thus at the opposite ends of the vertical lead portions 56a from the apertures 54.
The patterns and arrangements of the printed circuitry 53 in the manner of the present invention allow for connections between a set of relatively narrowly spaced apertures 54 and a ~ 3~ 7 _ I
1 1 set of relatively widely spaced con~ac~ pads 57. In this regard 21 it will be noted that the horizontai center spacing between the 31 apertures 54 in a given row is less than the vertical center 41 spacing between the pads 57, as desired. Moreover, vertical spacing between the terminal pads 57 can be increased or decreased 6 as desired to accommodate existing, conventional edge conn~ctors, 7 such as are shown, for example, a~ 60 in Figure 7; and, that 8 within relatively wide limits, the variations in pad spacing 9 can be made independently of aperture spacing. I refer to the foregoing as an "access circuit" or "access pattern of printed 11 circuitry" and it will be appreciated that this f~ature has 12 enabled electrical connections to be made bet~een a source of 13 data signals and a large number o~ clos~ly positioned small 14 apertures, as required ox desired ~or high density printing in a modulated aperture printing system of the type described. It 16 will also be appreciated that by printing access circuitry on a 17 flexible circuit board, the necessary connections can be made in 18 an efficient and econol..ic manner with conventional connectors.
19 The connection of the printed circuit board with conventional edge connectors is illustrated at Figure 7. As shown 21 in Figures 6 and 6C, a U-shaped sli~ 61 is cut through the circuit 22 board 51 to form a flap 63. It will be note~ ~hat Figure 6 shows 23 only that portion of the circuitry of the entire flexible circuit 24 board associated with a single flap 63. This basic circuitry pattern is repeated by translation of the pattern along a line 26 parallel to the row of apertures 54, and.then essentially by ?7 reflection through that line and translations parallel to it as 29 required to accommodate any numbers of apeetures 5~.

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The reflected pa~terns may ~e displaced laterally or otherwise 2 modified slightly to stagger ~he apertures and/or flaps as 31 re~uired or desired, as will be apparent. Thus, of the total 4 number o~ paired apertures 54 and terminal pads 57, there is a 51 separate group of such paixed apertures and pads associated with 61 each flap 63, and each such group has a pattern of leads 56 71 similar or identical to the patterns of leads 56 in every other 81 grouping. The pattern in each such grouping typiPied by the 91 pattern shown in Figure 6 wherein the flap 63 is positioned at 10¦ the right hand side of the pattern near the horizontal edge of Il the circuit board 51. The flap is formed to fold back along a 12 line perpendicular to the row of apertures S4 and the terminal 13 pads 57 are positioned on ~he ~lap in two horizontally spaced 14 rows. Terminal pads 57 in one vertical row are aligned with .
those terminal pads 57 in the adjacent row. The terminal pad at 16 the outermost edge of the circuit board 51 (hereinaf~er the 17 "first terminal pad" o the group) is connected to the aperture .
l$ 5~ positioned at the furthest left-hand end of ~he row of 19 apertures 54 in the group (the so-called "first aperture" of the group). The lead 56 between this particular aperture-terminal 21 pad pairing consists entirely of a straight vertical section 56c 22 joined at an elbow or junction 56b. The~aperture 54 to.the 23 Lmmediate right of the first aperture 54 tthe so-called "second 24 aperture" of the group) is associated with the "second terminal 2S pad'i, positioned in the row opposite the first terminal pad.
26 As shown in Figure 6, the second terminal pad 57, instead o~
27 being hori~ontally aligned with the first terminal pa~ 57, is 28 spaced a short distance inwardly ~i.e. toward or proximally to the ~291 ~ - 16 -I ' ~03~
row of apertures 5~) and is horizontally aligned with the third terminal pad; however, it will be readily appreciated in an alternate pattern, the second terminal pad 57 could be positioned in horizontal alignment with the first terminal pad. The "last"
aperture in the group, i.e. aperture located at the right-hand end of the row of apertures 54 in the group, is associated with one o~ the two terminal pads 57 located closest to the row of apertures 54. The vertical lead section 56a associated with the last aperture-terminal pad pair is, instead of being a continuous straight line, interrupted by an angled portion 56d, which dis-places the vertical lead sec-tion 56a to the left as it progresses from the aperture 54 to the junction 56d~ All vertical lead sections 56a, except the one at the furthest left-hancl side o~
the group and poss.ibly one or two others immediately adjacent to it, have visibly discernible angled portions 56d. The angles of the angled portions relative to a line perpendicular to the row of apertures increases gradually from left to right. For example, as shown, these angles begin at 0 in angled portions at the left-hand side of the group and increase to about 45 in angles at the right-hand side of the group, although it will be appreciated that this angle could increase to 90 as required by the geometry of the access pattern. It will be noted further that the junction points 56b lie in a line which runs at an angle to the row of apertures from a distal ar outer junction point associated with the first aperture-terminal paid pairing to an inner or proximal junction point associated with the last aperture-terminal pad pair. As the angle of the junction point line relative to a line parallel to the row of apertures 54 increases, ., ~38~7 ¦ the ~ertical spacing between the centers of the terminal pads 57 2 I can be increased proportionally. It will be appr~ciated that more 3 I or less aperture-terminal pad pairs may be ncluded in a given ¦ connector grouping, as desired, or as may be dictated by the

5 I numbers of terminals in a conventional off-the-shelf edge

6 ¦ connector 60/ as shown in Figure 7. Further, while Figure 6

7 ¦ illustrates an access pattern wherein the first or longitudinal

8 ¦ section 56a of the linear lead 56 extends in a direction

9 ¦ perpendicular to the second or lateral section 56c of the lead

10 ¦ 56, and angle of intersec~on (the junction angle at 56b) of the

11 ¦ first and second sections 56a and 56c could be any angle between

12 ¦ 0 and 180, although 90, as shown, is generally prcferred. In i3 ¦ addition, while the angles at all junctions 56b in a g~ven 14 ¦ grouping are preferably the same, they could be variable, for 15 ¦ example, to give the second sections 56c a fanned appearance as 16 ¦ would be the case if the first junction angle 56b (at the left-17 ¦ hand side of the grouping) were 170, the last junction angle ~81 56b were 10, and all other gradually varied in sequence there-¦ between.
20 ¦ In an ion modulation system, preferred aperture size 21 ¦ is on the order of 0.01 inch diameter with center spacing of 22 ¦ 0.02 inch. Due to the ~elatively low mass of ions, low voltage 231 gradients on the order of lS0 volts may be employed, and 241 insulators constructed of polyimide may be employed in thicknesses 251 on the order of 0.002 inch. ~hese dîmensions and ~oltage gra~.ient ~61 must be increased as necessary if other larger and/or heavier 271 charged particles, such as toner particles, are employed.
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3~ - 18 -B. Mountiny Assem~l~y ~or the Flexible Circuit Board:
In Figure 7, the f].ap 63 of the flexible circuit board 51 is shown connected to terminals of a conventional printed circuit board edge connector 60. Filler block 62 wedges the surface of the flap 63 between and against the opposed rows of pronglike edge connector terminals 64. Reliable electrical connections may be assured with solder. Figures 8-8C illustrate one embodirnent of the mounting assembly of the present invention wherein a flexible circuit board 51 of the type illustrated in Figure 6 is mounted on a card cage 71. So mounted, the surface of the circuit board 51 assumes an irregular shape with a central crest 74 and first and second lateral planar portions 72 and 73 respectively disposed at 90 relative to one another, as though folded across the edge of a box. The rown of apertures 54 oE
the circuit hoard 51 are d.isposed along th~ lencJ~h of the crest .portion 74. Crest support 75 positions the crest portion 74 and carries corona ,electrode wire 70 just beneath and parallel to the rows of apertures 54. The flexible circuit board 51 is mounted with its printed circuit leads 56 faced downwardly toward the cage 71. Conventional edge connectors 60 are connected to the circuit board 51 in the manner best illustrated by Figures 8A-C.
Filler blocks 62 are visible in the circuit board openings left by the folded flaps 63. Conventional printed circuit cards 80a, b are inserted edgewise into openings 81 in the card cage 71 so that their terminal bearing edges slide between the terminal contacts 76 of the edge connectors 60 in the conventional manner.
The non-terminal bearing edges o~ circuit cards 80a, b are supported by guides 65. The cards 80a inserted from one side of the cage 71 alternate with the cards 80b inserted fro~ the - 1~31~0~1L7 adjaccnt side of the card cage 71. Alternate cards 80a an-d 80b are inserted from directions perpendicular to each other and plug into edge connectors 50 located at the opposite sides of the card cage 71 from the entry slots 81. Thus, the cards 80a and 80b connect to circuitry carried on portions 73 and 72, respectively, of the circuit board 51.
Figure 9 illustrates an alternate embodiment of a card cage 91 for use in accordance with the present invention. In most respects, this embodiment is essentially the same as the embodiment illustrated in Figures 8-8C, having conventional printed circuit cards 92, conventional edge connectors (not visible), a crest support 94, corona electrode wi.re 95.
Essentially the same flexible circuit board 51 is used as that shown in Figures 8-8C although it will be n~ted that the edge connector flaps on opposite sides of th~ row o~ moclulatin~
apertures 54 are aligned, rather than staggered as shown previously since opposed pairs of flaps are associated with a single circuit card 92. As shown, the lateral sides 72 and 73 of the flexible circuit board lie in the same plane on eithe.r side of the crest portion 74. It will be apparent that each card 92 has two sets of circuitry since adjacent pairs of cards 80a, ~ in the previous embodiment are here combined.
C. Alternate Embodiments:
It will be noted that in.the embodiments previously discussed, for example, as shown in detail at Figure 6A, two offset rows of apertures 54 are employed as preferred. Thus, when apertures are spaced approximately and preferably slightly less than one aperture's diameter from adjacent apertures in ~L~38C1 ~7 the same row, apertures in one row will print dots which nearly or preferably actually touch dots printed with the adjacent aperture row, provided the aperture rows are actuated sequentially and the print receiving medium is translated vertically in appropriately timed relation to the row actuation sequencin~.
This provides essentially full line coverage so that hicJh quality character deinition can be achieved.
Numerous variations can be made in the aperture patterns without departing from the spirit of the present invention. For example, instead of two offset rows of apertures accessed from opposite sides o the flexible aperture board (circuit board) as shown in Figure 6, the two ofset rows could, with sligh-tly thinner leads 56 or annular conductive portions 55, be accessed from the same side, or four rows could be acces~ed, two from a side. Moreover, while the rows of apertures normally lie in a line generally perpendicular to the path of the paper, they can be disposed diagonally thereto or even randomly if desired.
It will be understood that these and other variations and modifications can be effected within the spirit and scope of the present invention as described hereinbefore and as defined in the appended claims.
D. Summary of Invention:
From the foregoing, it will be apparent that modulated aperture line printing requires a large number of apertures to be electrically accessed to driver circuitry. The difficulty of this task, due to crowding, increases universally in relation to 1~3~0~7 the sizes and directly in relation to the numbers of the apertures, so that where it is desired to modulate an ion stream utilizing large numbers of very small apertures (by comparison to the larger sizes and smaller numbers of apertures employed to modulate a stream of charged toner particles) the value of the present in-vention in furnishing electrical access to the apertures can be readily appreciated. It will be further understood that the large numbers of electrical connections which must be made between the access circuitry and driver circuitry has been greatly facilitated by the fact that the circuit board is flexible and, therefore, can be conveniently connected in groups with conventional edge connectors~
The invention has been descxibed in cons:iclerable detail with particular reference to cer~ain preferred embodiments thereo, but it will be understood that ~ariations and modifications can be effected without department from the spirit and scope of the invention.
This application is a division of copending Candian application Serial No. 199,377, filed May 9, 1974.

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Claims (9)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electrostatic printer head assembly comprising:
a. a flexible circuit board comprising i. a substrate of dielectric material;
ii. a continuous electrically conductive coating dis-posed on one side of said substrate;
iii. a plurality of apertures extending through both said substrate and said coating; and iv. a plurality of electrically conductive continuous strips mounted on the opposite side of said sub-strate from said coating, each of said strips hav-ing first and second sections, said first sections extending in a generally longitudinal direction between one of said apertures and said second section, said second section extending from said first section to a terminal portion, said first and second sections intersecting at an angle, said ter-minal portions center spaced more widely than said apertures to facilitate attachment to the terminal posts of external circuit card edge connectors, said terminal portions positioned on flexible flaps formed in said substrate;
b. a frame having a first side for supporting said flexi-ble circuit board and a second side opposite said first side provided with a slot;
c. a circuit card carrying an electrical circuit dis-posed edgewise in said slot; and d. an edge connector mounted on said first side of said frame and attached to said flap of said circuit board to provide separate electrical connections to each of the terminals on the flap, said edge connector having a groove which receives one edge of said circuit card to provide electrical connection with said circuit.

2. An electrostatic printer head assembly comprising:
a. a flexible circuit board having i. a flexible substrate of dielectric material;
ii. a continuous flexible electrical coating disposed on one side of said substrate;
iii. a plurality of apertures extending through both said substrate and said coating;
iv. a plurality of electrically conductive flexible continuous strips disposed on the opposite side of said substrate from said continuous coating, each of said strips extending between and electrically connecting one of said apertures to a terminal pad; and v. a plurality of terminal pads disposed on the same side of said substrate as said continuous strips;
b. means for supporting said flexible circuit board;
c. a printed circuit card carrying an electrical circuit;
d. means supporting said printed circuit card with its edge adjacent said terminal pads of said flexible circuit board;
e. means for forming an electrical connection between said electrical circuit on said card and said terminals.

3. Apparatus as recited in claim 2 wherein said electrical connection forming means comprises a conventional printed circuit card edge connector.

4. Apparatus as recited in claim 3 wherein said edge connector has two parallel rows of terminal prongs pro-jecting from one side thereof; and, further comprising an elongate filler block disposed between said rows of terminal prongs to wedge said circuit board flap between said block and said prongs and thereby urge said terminals on said circuit board against said terminal prongs of said edge connector to provide electrical connection therebetween.

5. Apparatus for aperture modulated electrostatic printing, comprising:
a substrate of dielectric material;
a continuous electrode disposed on one side of said substrate;
a plurality of apertures extending through both said substrate and said continuous electrode;
a plurality of closely spaced electrical devices, each associated with one of said apertures;
a plurality of electrically conductive leads disposed on said insulating layer each of said leads extending between one of said electrical devices and a terminal portion, said terminal portions of said leads arranged in one or more groups on a flexible flap formed in said substrate;
a frame having at least a first side for supporting said substrate;
at least one edge connector mounted on said first side of said frame, said edge connector having at least one row of terminal prongs facing said mounting means and a groove facing oppositely for receiving the edge of a circuit card, and means for wedging said flap against said prongs to provide elec-trical contact between said prongs and said terminal portions.

6. Apparatus as recited in claim 5 wherein said electrical devices are arranged in one or more parallel row(s) on said mounting means, wherein there is at least one of said terminal portion bearing flaps disposed on either side of said row(s) of electrical devices; wherein said frame is provided with a second side and a central crested portion between said first and second sides of said frame; and wherein said first and second sides of said frame support at least one of said terminal portion bearing flaps, respectively and at least one of said edge con-nectors mounted on said second side for electrical connection with adjacent ones of said terminal portions.

7. Apparatus as recited in claim 6 wherein said mounting means is flexible and shaped to the configuration of said first and second sides and said crested portion of said frame;
wherein said crested portion support said row(s) of electrical devices, wherein a corona ion source is disposed in said crested portion adjacent said electrical devices; and wherein said electrical devices are ion stream modulating apertures adapted for modulated aperture electrostatic printing.

8. Apparatus as recited in claim 7 wherein said frame is substantially rectangular in cross-section, said first and second sides of said frame lying in substantially perpendicular planes.

9. Apparatus as recited in claim 7 wherein said frame is substantially rectangular in cross-section, said first and second sides of said frame being coplanar.