US2375267A - Automatically adjustable recording means - Google Patents

Description

May 8, 1945. R. J. WISE 2,375,267

AUTOMATICALLY ADJUSTABLE RECORDING MEANS Filed Feb. 12, 1942 FIG. I

INVENTOR 56 R.J.WISE

Patented May 8, 1945 AUTOMATICALLY ADJUSTABLE RECORDING MEANS Raleigh J. Wise, Dunellen, N. J assignor to The Western Union Telegraph Company, New York, N. Y., a corporation of New York Application February 12, 1942, Serial No. 430,531

6 Claims.

The present invention relates to electrically operated facsimile telegraph or copying systems of the type employing a marking point operatively engageable with a. recording surface and more particularly to means for automatically maintaining the marking point in signal tracing relationship with respect to the recording surface.

Systems of this type usually include a supporting means such, for example, as a fiat or curved platen for receiving a record sheet or web, or a recording cylinder around which a record sheet is wrapped. Relative movement between the record sheet and the marking point may be obtained by various means to produce scanning of the record sheet by the marking point for recording purposes. Such movement produces friction so that the marking point is worn away, with the result that the recorded marking on the blank varies in character as the recording proceeds. Where the marking point is in the form of a pencil of marking medium to be deposited upon the recording surface, the pencil wears away rapidly and unless the recorder is continually adjusted by an attendant the character of the marks will change. Where the marking point is in the form of a cutting stylus or engraving point, wear may be less rapid but, because of the nature of the recorded copy, the system is particularly subject to defects in recording caused by the wear of the marking point. These remarks apply more particularly to systems for producing master copies and. also to embossing and engraving systems. In systems of the type including an electrically conductive supporting surface for the recording blank and a marking point in the form of an electrified stylus, the result of wear is not so marked as in the previously mentioned systems, since the stylus is usually resiliently mounted. However, the degree of pressure exerted upon the recording surface by the resiliently mounted stylus should be maintained substantially constant until the useful portion of the stylus is substantially worn away, a condition which is obtained by employing the novel adjusting arrangement of this invention.

In practising the present invention, the ill effects of wear of the marking point in a particular system in which the invention is used are overcome by automatically maintaining a definite spacing of the marking point, in its idle position, with respect to the recording surface, or by maintaining a, substantially constant pressure of the marking point on the recording surface in systems where the marking point is maintained at all times in contact with the recording surface.

An object of this invention, therefore, is to provide compensation for wear of the marking point during recording in a facsimile telegraph or copying system and thereby to maintain the condition of signal tracing relationship of the marking point and the recording surface at an optimum value.

A further object of the invention is to provide a novel and improved recording device which is self-acting to maintain the relationship of the stylus and recording surface substantialy constant during recording.

A still further object of the present invention is to provide an improved stylus adjusting arrangement which is automatic in operation.

More specific objects of the invention defined by the terms of the appended claims, in addition to th broader objects set forth above, will be apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a top plan view, to an enlarged scale, of a recording unit and its mounting embodying an illustrative form of the present invention; and

Fig. 2 is a view in side elevation of the mounting disclosed in Fig. 1.

The embodiment of the invention illustrated by Figs. 1 and 2 of the drawing is similar in its general arrangement to the electromagnetic recording unit and recording unit mounting disclosed in Patent No. 2,260,862, granted to F. L. OBrien et al., on ()ctober 28, 1941. It will be understood that the invention may be employed in connection with a piezo-electric or any type of.,trdnsducer or recording unit. The recording unit It) is designed to operate a marking point H in accordance with facsimile signals derived in any known manner (not shown) and applied to the coil I! of the recorder by way of conductors H. The recording point II which, in the exampl shown, may comprise a pencil of marking pigment, such as the lead of a pencil, produces marks on a sheet of recording paper lt'mounted on the surface of a rotary recording drum H. The recording unit In and the supporting parts by which it is carried are mountedupon a channel-shaped plate l8 which is movably carried in any known manner to cause the marking point II to trace a helical path on the drum H as the drum is rotated. The up-standing flanges IQ of the channel-shaped plate are provided with trunnion screws 2| which pivotally support an angular bracket 22, upon which the recording unit I3 is secured by an insulating block 23. The bracket 22 has an extension 24 secured thereto which is adapted to engage the end of a micrometer stop screw 25 threaded into a stationary member 21. The screw 25 abuts the extension 24 so as to provide for adjustment of the marking point H with respect to the surface of the paper It in position on the drum n. The stationary member 21 in the illustrated embodiment is secured to the frame or shell 23 of a solenoid electromagnet 23. The portion of the member 21 which carries the screw 25 is slotted and apertured to receive a screw 3| which functions frictionally to maintain adjustment of the screw 26. The head of the screw 25 is provided with a knob or thumb piece 32 so that manual adjustment of the marking point may be obtained when desired. The electromagnet 29 may be energized by current from any desired source controlled by a suitable switch or the like. The circuit for accomplishing this is connected to the leads 33. It will be understood that in telegraph or facsimile recorders, the electromagnet 23 will usually be automatically controlled for the purpose of positioning the stylus in operative or inoperative position with respect to the surface of the paper IS.

The recording unit l may be of any desired type suitable for the recording system in which it is employed and, as mentioned previously, in.- cludes the operating coil |2 which serves to vibrate a tongue or armature 34 to which the marking point II is secured. The point H, in the arrangement shown, is contained in a barrel 36 provided with a removable screw 38 to facilitate its removal and replacement.

-In order to provide for adjustment of the marking point II in accordance with the invention, the screw 25 carries a ratchet wheel 4| which is engageable by a pawl 42 pivotally mounted on the armature 43 of an electromagnet 44. A spring 45 maintains the pawl 42 operativel in engagement with the ratchet wheel 4| and another spring 41 maintains the armature 43 in its deenergiZed position. A bracket 49 secured 'by screws to the frame of the electromagnet 44 provides a stationary anchorage for the spring 41. The bracket 43 also carries a stop 52 which limits movement of the armature 43 under the influence of the spring 41 to an amount such that the pawl 42 advances the ratchet wheel angularly by one tooth for ach energization of the electromagnet 44.

The stop 52 may be adjusted by bending it or, if adjustment for a larger range of movement of the pawl is desired, an adjustin screw may be provided in a well-known manner so as to permit the pawl 42 to move the ratchet wheel 4| through an annular distance of one or more of its teeth for each energization of the electromagnet.

Energization of the electromagnet 44 is controlled by a pair of contacts 53 and 54 through a vacuum tube relay 56. It will be understood that these contacts may operate a. space discharge or electromagnetic relay of any type which may be inte posed between them and the electromagnet 44. The contact 53 is carried by the recorder armature 34, while the contact 54 is secured to a spring arm 58 which is secured to but insulated from the recording unit l0 by insulating members 59 and a fastening screw 6|.

The electromagnet 44 is connected in the anode circuit of the tube 53 together with a suitable source of anode current 82. The grid 53 of the tube is biased negatively by a source of biasing potential 54 so that substantially no anode current flows in the coil of the electromagnet 44 when the contacts II and 54 are open. A resistor 55 oi relatively high ohmic resistance is inserted in the grid circuit of the tube and a condenser 51 shunts the biasing source 64 and the resistor 85.

A switch 83 is provided so that the automatic adjustment feature may be cut out when desired. When the grid 53 of the tube is grounded by momentary engagement of contacts 53 and 54, the plate current of the tube increases to energize the magnet 44, and upon separation of the contacts 53 and 54 this plate current is maintained durin a portion of the time taken to recharge the condenser 67!.

With the cylinder rotating in the direction of the arrow on Fig. 2 of the drawing. the marking point II will mark the surface of the recording sheet It in a helical path, as explained above, in accordance with facsimile signals applied to the conductors I4. As recordin proceeds and the marking oint wears, contacts 53 and 54 will engage to energize the magnet 44, as explained above. The condenser 61 insures that the magnet 44 will be energized for a period sufficiently long to obtain a full stroke of the pawl 42 even though the contacts 53 and 54 only touch momentarily and are separated almost immediately. The movement of the pawl 42 results in rotation of the screw 25 through a small angular distance equal to the angular spacing of the teeth on the ratchet wheel 4 I, thus bringing the recording unit l0 together with the marking point ll nearer to the surface of the record sheet by an amount which may be made substantially equal to the amount of wear on the marking point I I.

In systems provided with this invention and employing an embossing or cutting point, the depth of the embossing or the depth of out will not vary materially as recording proceeds so that the embossing or engravin may be used to reproduce copies of the original by a mechanical method such as printing with ink.

As stated above, the invention may be applied to electrical recording systems wherein signals to be recorded are applied across the recordin cylinder I! with the marking point ll serving as an electrified stylus. When the invention is applied to apparatus of the form just described, an adjusting screw 26 having a thread of ver fine pitch is preferred, and also the teeth on the ratchet wheel 4| should have a small annular pitch. In this manner the relatively minute amount of stylus wear will be compensated for by a, minute amount of movement of the angular bracket 22 with respect to the drum I! when wear becomes sufllcient to cause the contact 53 to engage the contact 54.

When the invention is applied to an electrical recording system wherein the signals to be recorded are applied between the cylinder and the marking point serving as an electrified stylus, a very fine adjustment for the minute wear on the stylus oint is sufficient and the condenser 31 may be omitted, if desired. Fine adjustment is possible because even though the contacts 53 and 54 are separated almost immediately by partial movement of the pawl 42, the ratchet wheel 4| will remain in its partially adjusted position by reason of the frictional effect of the screw 3| until further wear has been experienced by the stylus, whereupon the pawl 42 will or may repeat its partial stroke, and this will continue until the pawl 42 completes its stroke and returns under the action of the spring 41.

From the foregoing it will be seen that this invention provides a ready means for compensating for the wear of the marking point in an electrically operated copying system so that conditions effecting recording will remain substantiall unchanged throughout the life of the copyiiig point.

While the invention has been described and shown in connection with an illustrative embodiment thereof, it will be understood that many modifications and changes may be made in the structure shown without departing from the essential attributes of the invention, and all such changes are contemplated as coming within the scope of the appended claims.

What is claimed is:

l. The combination in a telegraph recorder of mechanism "for marking a recording blank including a recording stylus having a point adapted to engage said blank for producing a record thereon in accordance with received signals, means for holding said stylus in operative position with respect to said blank for relative scanning movement across the surface thereof, and means for compensating for the effect of wear on the stylus point comprising an electromagnet and structure controlled thereby for advancing said stylus holding means in steps towards said recording blank. and circuit means controlling said electromagnet comprising switch contact elements automatically operative when the point of said stylus has worn down a predetermined extent for energizing said electromagnet.

2. The combination in a telegraph recorder of mechanism for marking a recording blank including a recordin stylus having a point adapted to engage said blank for producing a record thereon in accordance with received signals, means for holding said stylus in operative position with respect to said blank for relative scanning movement across the surface thereof, and

means for compensating for the effect of wear on the stylus point comprising an electromagnet and pawl and ratchet structure controlled thereby for advancing said stylus holding means in steps towards said recording blank and circuit means controlling said electromagnet comprising switch contact elements automatically operative when the point of said stylus has worn down a predetermined extent for energizing said electromagnet.

3. The combination in a telegraph recorder of mechanism for marking a recording blank in-c eluding a recording stylus having a point adapted to engage said blank for producing a record thereon in accordance with received-signals, means for holding said stylus in operative position with respect to said blank for relative scanning movement across the surface thereof, and means for compensating for the effector wear on the stylus point comprising an electromagnet and structure controlled thereby for advancing said stylus hold- 4. The combination in. a telegraph recorder oi mechanism lor marking a recording blank including a recording stylus having a point adapted to engage said blank for producing a record thereon in accordanc with received signals, a pivotally mounted support- Ior holding said stylus in operative position with respect to said blank; Ior relative scanning movement across the surface thereof, and means .t'or compensating for the effect of wear on the stylus point compris ing an. electromagnet and structure controlled thereby for rotating said pivotaily mounted stylus support in steps towards said recording blanls and circuit means controlling said electromagnet com prising switch contact elements automatically operative when the point of said stylus has worn down a predetermined extent for energizing said electromagnet.

5. In a recorder, a record receiving medium, a marking point, a holder for said point capable of adjusting the position of said point with respect to the surface of said medium, means includin electrical contacts controlled by said marlring point and said surface and automatically operative in accordance with the extent of wear of said marking point, electromagnetic means for producing adjustment of said holder, a vacuum tube relay interposed between said contacts and said electromagnetic means to control the latter, and means operatively connected with said vacuum tube relay to prolong the effect of the operation of said contacts.

6. In a recorder, a marking device, a movable support for said marking device, means to sup- 7 port a member having a record receiving surface in operative position with respect to said marking device, means including an electromagnet for adjusting the position of said markin device with respect to said record receiving surface, a marking point forming an operative part of said marking device, electrical contact means controlled by said marking point and said rec 0rd receiving surface and automatically operative in accordance with the extent of wear of said marking point, a vacuum tube relay having an input circuit and an output circuit, said electromagnet being included in the output circuit of said relay, and a source of biasing potential included in the input circuit of said vacuum tube

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