US3921181A

US3921181A - Compliant printer blade for facsimile printer

Info

Publication number: US3921181A
Application number: US449738A
Authority: US
Inventors: Frank W Hauser
Original assignee: Telautograph Corp
Current assignee: Telautograph Corp
Priority date: 1974-03-11
Filing date: 1974-03-11
Publication date: 1975-11-18
Anticipated expiration: 1992-11-18

Abstract

An improved printing blade for a facsimile printer of the drum type is made out of a thin strip of stainless steel. The blade is inserted into a rigid blade carrier and locked firmly in place by a spring-biased eccentric locking roller. The carrier is mounted on the printer in such a position as to cause the edge of the blade to bear against web material over a helical wire on the printer drum with sufficient force to maintain the blade against the web material. The inherent resilience of the blade is sufficient to compensate for any differences in the radius of the helical wire from the axis of the turning drum and differences in the thicknesses of web material being passed between the drum and the blade.

Description

United States Patent [191 Hauser [4 1 Nov. 18, 1975 COMPLIANT PRINTER BLADE FOR FACSIMILE PRINTER [75] Inventor: Frank W. Hauser, Santa Monica,

Calif.

[22] Filed: Mar. 11, 1974 [21] Appl. No.: 449,738

[52] US. Cl. 346/73 E; 346/139 C [51] Int. C1. G03G 17/02; GOlD 15/06 [58] Field of Search 346/74 E, 74 CH, 74 S, 346/74 SB, 139 C; 178/6.6 A

[56] 9 References Cited UNITED STATES PATENTS 2,505,779 5/1950 Long 346/74 EL 2,621,999 12/1952 Alden 346/74 EL 3,491,365 1/1970 DeSautels 346/74 EL 3,546,707 12/1970 Dixon 346/74 EL 4/1974 Andree .1

Primary Examiner-Bernard Konick Assistant Examiner-Jay P. Lucas Attorney, Agent, or FirmLindenberg, Freilich, Wasserman, Rosen &- Fernandez 57 ABSTRACT An improved printing blade for a facsimile printer of the drum type is made out of a thin strip of stainless steel. The blade is inserted into a rigid blade carrier and locked firmly in place by a spring-biased eccentric locking roller. The carrier is mounted on the printer in such a position as to cause the edge of the blade to bear against web material over a helical wire on the printer drum with sufficient force to maintain the blade against the web material. The inherent resilience of the blade is sufficient to compensate for any differences in the radius of the helical wire from the axis of the turning drum and differences in the thicknesses of web material being passed between the drum and the blade.

2 Claims, 5 Drawing Figures US. Patent Nov. 18, 1975 Sheet10f2 3,921,181

Sheet 2 of 2 US. Patent COMPLIANT PRINTER BLADE FOR FACSIMILE PRINTER BACKGROUND OF THE INVENTION This invention relates to facsimile printers and more particularly to a printing blade for a facsimile printer of the type which employs a helical wire on a rotating drum and a blade parallel to the axis of rotation of the drum for recording an electrolytic web material passing between the blade and the drum in a direction perpendicular to the axis of the rotating drum.

The most common type of facsimile printer records on electrolytic paper by producing electrical charges across the paper at points where marks are to be made. In a drum-type of facsimile printer, the electrolytic paper is passed over a drum of nonconducting material around which a conducting wire is wound helically. A blade parallel to the axis of the drum bears against the drum asthe drum is rotating with the electrolytic paper passing between the blade and the drum in a direction perpendicular to the axis of the drum. Asthe drum rotates, the helical wire sweeps across the paper under the blade, thus defining a line virtually perpendicular to the edges of the paper along which points may be recorded by selectively energizing the helical wire. Recording is thus accomplished by modulating the energizing signal applied to an electrical circuit which includes the helical wire and blade. The paper advances slowly so that successive lines over the entire surface of the paper are scanned for recording. The electrical charge between the wire and blade causes ions in'the blade to enter the electrolyte of the paper and darken it to thereby mark a point on the paper. Each point is generally of almost square shape with sides of about 0.010 in. With drum speeds on the order of 1,000 RPM, and paper drive speed of about in. per minute, 100 lines are scanned to the inch of paper so that with points recorded of the size indicated, virtually no space is left between scanned lines.

The printing blade is electrolytically eroded as points are recorded, and the recording of a long continuous line can result in the formation of a deep groove in the blade. Such a groove may later interfere with proper recording and may tear the paper. One way of preventing the formation of grooves is by forming the blade as a continuous band held taut between a roller on one side of the paper and a driven capstan on the other side of the paper as shown in US. Pat. No. 3,569,987 assigned to Teleautograph Corporation by Kunio A. Sumida. The band is held inclined to the paper with a sufficient bias force to maintain the edge of the band against the paper, and with sufficient resilience in the band to compensate for differences in the radius of the helical wire from the turning axis of the drum and variations in the thickness of the paper. The bias force is provided by a leaf spring which contacts the loop belt immediately below its upper edge on the inside of the loop. However, this solution to the electrolytic erosion problem was found to be unsatisfactory because the continual motion of the rotating band in one direction has a tendency to cut the paper.

Another solution to this electrolytic erosion problem of the printing blade which has been successfully used is to mount a rigid blade on a carrier which is continuously driven with an oscillating motion back and forth across the paper. The rigid blade has been formed of a strip of metal bent about 90 down the center along its causing disturbing noise and non-uniform printing.

Normally, electrolytic printers are as quiet as magnetic tape recorders.

OBJECTS AND SUMMARY OF THE INVENTION One object of the present invention is to provide an improved printing blade assembly for facsimile printers of the drum type.

Another object is to provide a compliant printing blade for non-vibrating and silent facsimile printing.

In accordance with the present invention, there is provided for a facsimile printer of the drum type a printing blade apparatus comprised of a thin strip of resilient metal secured in a carriage along one edge, preferably by a spring-biased eccentric roller. The carriage is mounted on the recorder with the free end of the blade inclined at an acute angle with electrolytic paper being passed between the printing drum and the blade. The inclined position of the carriage and blade is adjusted to place the blade against the paper with sufficient force to maintain the blade on the paper as the drum rotates. The inherent resilience of the thin stainless steel blade provides the compliance required to compensate for variations in the radius of a helical wire wound on the drum and the thickness of the electrolytic paper. The carriage is provided with rods which pass through mounting brackets on each end to permit the carriage to beoscillated back and forth in the direction of the axis of the rods, thereby moving the blade back and forth on the electrolytic paper in a direction parallel to the axis of the drum. This motion reduces the tendency for electrolytic erosion to notch the edge of the blade when a long vertical line is printed on the paper.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims. The invention will bestbe understood from the following description when read in conjunction With the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view of a facsimile printer of the drum type having a printing blade and blade carriage assembly constructed in accordance with the present invention.

FIG. 2 is a sectional side elevation of the apparatus taken along a line 2-2 of FIG. 1.

FIG. 3 is an enlarged sectional view of the area 33 of FIG. 2.

FIG. 4 is a view in elevation of the blade carriage assembly of FIG. 3.

FIG. 5 is an exploded view of the blade and blade carriage assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a typical organization of a facsimile printer of the type which employs electrolytic paper 10 j and a helical wire 11 on a rotating drum 12 to successively scan and mark points on the paper at the points .of intersection between the helical wire and a metal printing blade 13. The paper is stored on a roll 14 ina sealed compartment 15. The paper passes over a guide 16 and out of the compartment through a slitbetween sealing members 17 and 18. The sealing member 18 is formed as a thin resilient strip of metal in order that the slit be closed by pressure of the strip against the paper and the rigid sealing member 17. v

The paper passes between the drum l2 and the printing blade 13, and from there over a heater not shown to drive'rollers, also not shown. The drive rollers pull the paper over the printing drum at a slow speed inches per minute) while the drum rotates at a speed 1,000 RPM) coordinated with the paper speed to produce printed lines substantially parallel to the drum axis (100 lines per inch) to virtually fill all of thespace (assuming points printed with a height of 0.010 inch). The printed paper leaving the feed rollers passes between cutting blades(not shown). The blades are actuated to cuteach printed document as it leaves the feed rollers.

The printing blade 13 is mounted in a carriage 19. The carriage is in turn mounted on the chassis of the recorder by

rods

20 and 20 passing through blocks 21 and 21 (FIGS. 4 and 5) at each end fastened to the chassis (not shown). Suitable means is provided to adjust the angular position of the carriage vis-a-vis the paper to maintain a high pressing force (about 175 grams) of the blade against the paper with an angle of approximately between the blade and the paper as shown in FIG. 2.

The blade is typically 9%. inches long, 9/16 inch wide and 0.004 inch thick. The metal selected for the blade is type-302 stainless steel for its qualities of resistance to chemical corrosion and resilience. Type-316 stainless steel would be even more suitable, but at the present time is too expensive for the application since the printing blade is subject to wear and must be replaced from time to time. Still other, and perhaps even cheaper, metals may be found with these desired qualities. Consequently, the present invention is not to be construed as being limited to stainless steel blades.

A new blade will have an almost square corner along its longitudinal edge bearing against the paper, but after a short burn-in time, thecorner will wear down to present a surface bearing against the paper of 0.010 inch as shown in FIG. 3. The diameter of the wire 11 is typically about 0.032 inch to provide backing for virtually all of the paper between the wire and the blade to the full height of 0.010 inch. This is so because the paper is sufficiently compressible to cause it to form itself around the wire. The result is that if an electrical potential is momentarily applied between the printing blade and the wire at any given instant, a point will be printed in the electrolytic paper that is 0.010 inch high, and virtually 0.010 inch square.

The carriage 19 for the blade is comprised of a long (9 /8 inch) block 22 into which set screws 23 pass to secure to the block 22 the

rods

20 and 20 at the ends thereof. In that manner only the rod ends of the carriage pass through the mounting

blocks

21 and 21 which are cylindrical to permit tilting the block forward with the blade against the drum and paper.

The carriage block 22 also has a beveled flange 25. That flange is beveled to permit the blade to be easily inserted through a slot between a cover 27 and the flange 25 with a flat side against the beveled side of the .flange while a spring-biased eccentric locking roller 28 is rotated out of the way by a lever 29 (FIG. 4). Aftc: the blade is seated, the leverof the locking roller is released and a coiled spring 30 rotates the locking roller back into the position shown in FIG. 2 against the blade. The force of the spring 30 holds the roller against the blade withsufficient force to lock it in position. The cover 27 is secured to the block'by screws 31.

FIG. 4 shows in elevation the blade carriage assembl; 19 just described, but as viewed from the front, i.e., from the drum side. FIG. 5 is an exploded view from the other side. The eccentric roller 28 is held in place for rotation by the lever 29 at one end passing through a hole 32 in an end plate 33 secured to the block 22 by screws 34, and by a slotted pin 35 passing through a hole 36 in an end plate 37 secured to the block 22 by screws 38. The lever 29 and the pin 35'are locked in position in the ends of the eccentric roller by respective set screws 39' and 39. One end of the coiled spring 30 at the center of the coil, is inserted into the slotted pin 35. The other end of the coiled spring is wraped around the head of one of the screws'38. When the lever is rotated clockwise, as viewed in FIG. 5, the eccentric locking roller is rotated away from the beveled surface of the flange 25 and the coiled spring is tightened. When the lever 29 is released, the spring rotates the eccentric locking roller back against the blade 13, to lock the blade in place. The entire blade carriage assembly 19 is held in a position near the mounting block 21 by a spring 40 connected between the block 21 and the carriage block 22.

The rod 20 on the left in FIG. 4 is covered by a plastic cap 41 against which an actuator cam 42 (FIG. 1) pushes to move the rod and carriage block to the right, as viewed in FIG. 4. The actuator cam is in turn activated by a drive rod 43 which is driven up and down through a gear train and an eccentric drive wheel(not shown) by the motor (also not shown) that drives the paper feed rollers. At the downward movement of the drive rod43 changes to upward movement, the spring 40 returns the rod and the carriage block to the position shown in FIG. 4. In that way the blade 13 is caused to oscillate back and forth in a path parallel to the axis of the drum 12 so that while printing one long continuous line parallel to the edges of the paper 10, there is not a tendency for the applied voltage to cause electrolytic errosion of the blade at one point.

As noted hereinbefore, the blade carriage assembly is rotated to a position that places the blade against the paper with over a hundred grams of force. The thin blade is sufficientlyresilient to provide desired compliance of the blade as the drum rotates to allow for deviation in theradius of the helical wire 11 from the turning axis of the drum and the thickness of the paper. That is accomplished by adjusting the position of a pin 44 (FIG. 4) which seats in a yoke 45 shown in perspective in FIG. As the pin 44 is moved forward in the direction of the drum, the blade carriage block 22 is rotated

on'the rods

20 and 20. The yoke 45 is mounted on a block 46 which is clamped on the end of the rod 20 by a screw 47. As the blade wears, the blade carriage block may be further rotated to keep the blade against the paper with the desired force. Wear of the blade will require this adjustment not more often than once each day of daily continuous use.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and equivalents may readily occur to those skilled in the art and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

What is claimed is:

1. An improved printing blade apparatus for use in a facsimile printer having a rotating drum with a helical conducting wire on the surface thereof for printing on an electrolytic web that moves over said drum in a direction perpendicular to the axis of rotation of said drum, said web passing between a blade parallel to said axis and said drum, said apparatus comprising a thin planar strip of metal held along one longitudinal end in a position to serve as said blade with an edge opposite said one end against said web, and

a rigid carriage means for holding said thin planar strip of metal along said one end with said opposite edge against said web and with said planar strip inclined at an acute angle with said web, said angle being selected for said opposite edge to point in the direction of motion of said web wherein said carriage means includes biasing means for adjusting the position of said thin planar strip against said web with a desired pressing force of said strip against said web to maintain said strip against said web as said drum rotates, whereby localized compliance of said strip is provided to allow for deviations in the diameter of said wire and distance of said wire from said drum axis, and for variations in the thickness of said web.

2. Apparatus as defined in claim 1 wherein said carriage is comprised of an elongated block having a longitudinal flat surface inclined at said angle, said flat surface being in front of said planar strip in respect to the direction of rotation of said drum, and a spring-biased eccentric roller bearing against said surface, whereby said roller may be rotated away from said surface to insert said thin planar strip between said roller and said surface, and then released to hold said strip in place with the curved surface of said roller behind said strip in respect to the direction of rotation of said drum to enhance said compliance of said strip.

Claims

1. An improved printing blade apparatus for use in a facsimile printer having a rotating drum with a helical conducting wire on the surface thereof for printing on an electrolytic web that moves over said drum in a direction perpendicular to the axis of rotation of said drum, said web passing between a blade parallel to said axis and said drum, said apparatus comprIsing a thin planar strip of metal held along one longitudinal end in a position to serve as said blade with an edge opposite said one end against said web, and a rigid carriage means for holding said thin planar strip of metal along said one end with said opposite edge against said web and with said planar strip inclined at an acute angle with said web, said angle being selected for said opposite edge to point in the direction of motion of said web wherein said carriage means includes biasing means for adjusting the position of said thin planar strip against said web with a desired pressing force of said strip against said web to maintain said strip against said web as said drum rotates, whereby localized compliance of said strip is provided to allow for deviations in the diameter of said wire and distance of said wire from said drum axis, and for variations in the thickness of said web.