BACKGROUND OF THE INVENTION

One known type of facsimile machine utilizes paper-charging apparatus which includes a stylus board made up of an insulating board which carries a large number of fine styli which operates with a backplane board made up of an insulating board which carries a plurality of small-area backplane electrodes. The two boards have a sheet of paper between them, and they are energized to provide charging signals which charge the paper. The styli all terminate at an edge of the stylus board, and it is necessary for the styli to make intimate contact with the recording paper along the entire length of the backplane board or at least be uniformly spaced therefrom along their mating lengths. This has been difficult to achieve, and relatively costly and time-consuming steps have been required to attempt to solve the problem.

The present invention solves the problem and provides intimate operating contact between the styli and the paper by providing a compliant material which holds the backplane, the paper, and the styli in uniform contact.

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Description of the Drawings

Fig. 1 is a perspective view of the invention;

Fig. 2 is a front elevational view of a stylu board used in Fig. 1. Fig. 3 is a front elevational view of backplane board used in Fig. 1;

Fig. 4 is a sectional elevational view of portion of the apparatus of Fig. 1;

Fig. 5 is a top view of the apparatus of Fig 1;

Fig. 6 is a front elevational view of th apparatus of Fig. 1;

Fig. 7 is a side elevational view of th apparatus of Fig. 1; Fig. 8 is a sectional view of a portion of th apparatus of Fig. 7; and

Fig. 9 is a sectional view along the lines 9- in Fig. 6 .

Description of the Preferred Embodiments

The electrostatic paper-charging apparatus o the invention 10 includes a metal support ^' plate 2 having a large-area main body portion 30 and a T-shape support bar 40 along one edge. The apparatus 10 includes a stylus board 5 which comprises a sheet of insulating material, of th type normally used in a printed circuit board, having front surface 52 on which are formed, by printe circuit techniques, a large number of styli 60 (Fig 2) . The styli (not all are shown) are disposed acros the length of the board and are in the form of thi metal conductors which are insulated from each othe and terminate at the upper edge 70 of the board. Th styli are also connected to plug-in edge connectors 8 disposed along the opposite edge 90 of the board. Th

shape and electrical connections of the styli are not critical as far as the present invention is concerned.

The stylus board 50 is placed in contact with the T-shaped portion 40 of the support plate and is

._. held in place by means of a cross bar 100 which extends across the board in contact therewith and is secured to the T-shaped member.

The apparatus 10 also includes a backplane board 110 which comprises a strip 112 of insulating

10 material, preferably flexible, to permit intimate engagement with stylus board 50. The strip 112 has a front surface 114, on which is formed a plurality of parallel backplane electrodes 120, each of which is in two parts 120A and 120B, with a small gap 130 between

¹ 5 the parts, the gap being adapted to receive the stylus board, as represented by the dash lines in Fig. 3. The backplane board 110 is mounted transverse to the stylus board 50, as seen in Figs. 1 and 5-9.

According to the invention, a strip 140 of

²⁰ flexible material such as foam rubber or the like is secured to the rear surface 116 of the backplane board 110, extending along the length thereof behind the backplane electrodes 120. The assembly of backplane board and rubber strip 140 is secured to a metal plate

² 5 150, with the rubber strip engaging the metal plate and cemented thereto. The plate 150 has, at its ends, pins 152, which are disposed in slots 158 in bracket 160. The weight of the plate 150 causes the backplane board to press against the stylus board and provide intimate

3° contact with the styli along its length.

The bracket 160 is pivotally coupled by pin 164 to a bracket 166, secured to plate 20, and it is guided on a pin 172 which carries a srping 174 which biases the bracket 160 and its component parts

- ^> - ^> downwardly. The pin and bracket assemblies are

-h-

provided at both ends of the apparatus 10.

The actual practice in one type of apparatus the styli are provided in two sets, and two stylu boards are provided as shown in Figs. 7-9. Two are no shown in Figs. 1 and 4.

In operation of the apparatus 10, a sheet o paper 180 (shown in Figs. 1 and 8) is move line-by-line between the stylus board and the backplan board, and electrical signals applied to the electrode carried by these boards provide lines of electrostati charges. After the entire sheet has been charged, i is passed through a toner and fuser to render th electrostatic charge pattern visible and permanent.

One specific machine with which the apparatu of the invention may be used is known as the Dex 510 machine of Burroughs Corporation. Portions of thi machine are described and claimed in copendin applications Serial No. 21,493, filed March 19, 197 and Serial No. 12,522, filed February 15, 1979, whic are incorporated herein by reference. The latte application illustrates one mode of operatin electrically the stylus and backplane electrode described herein.

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