US2421438A - Phasing and drive-coupling arrangement for facsimile machines - Google Patents

Description

June 3, 1947. SHQIQNARD I 2,421,438

PHASING AND DRIVE-COUPLING ARRANGEMENT FOR FACSIMILE MACHINES Filed Dec 31,1943

FIG. 1

INVENTOR. J OHM R SHONNARD Patented June 3, 1947 PHASING AND DRIVE-COUPLING ARRANGE- MENT FOR FACSIMILE MACHINES John R. Shonnard, New York, N. Y., assignor to Times Facsimile Corporation,

New York a corporation of Application December 31, 1943, Serial No. 516,341

This invention relates to telegraph machines and more especially to driving and phasing arrangements for facsimile scanning drums and the like.

In the operation of facsimile systems employing rotating scanning drums, it is usually requisite before the start of a transmission period to phase the drums at the transmitter and receiver, even though the drums otherwise would run in perfect speed synchronism. This phasing operation is particularly important where one of the drums is comparatively heavy, or where the drum rotates at such a high speed as to have considerable inertia. This problem of phasing has been found to be particularly difiicult with large or heavy drums because of the comparatively great and sudden load which is placed upon the driving mechanism at the instant of phasing. Heretofore, the phasing operation has required almost an instantaneous change from no load to full load on the driving motor and on the clutch between the motor and the drum. Since such clutches are usually of the slip-friction type, it is clear that this sudden change from no load to full load is represented by a considerable slip in the clutch with a consequent undesirable change in phase between the received phasing impulse and the actual angular phase of the drum.

Accordingly, one of the principal objects of the present invention is to provide a drive cou pling between a slip-friction clutch and a scanning drum whereby the load on the clutch and the driving motor is materially reduced during phasing operations and the like.

There is one known type of phasing arrangement as illustrated for example in Patent No. 2,275,249, wherein the scanning drum is arranged to be stopped by an abutment which engages a projection on the drum or drum drive. With such an arrangement, the drum is connected at all times to the driving motor shaft either directly or through the slip-friction clutch. Consequently, there is no possibility of the drum coasting freely with respect to the motor.

Another object is to provide a drive coupling between a motor and a scanning drum which, under certain conditions, permits the drum to rotate freely and substantially independently of the usual slip-friction clutch.

A further object is to provide an improved phasing control mechanism whereby the scanning drum can coast while the clutch is stopped, and when the clutch is released it applies a positive drive to the drum, the application of which 8 Claims. (Cl. 178-695) positive drive can take place while the drum is coasting and which positive drive is necessary to maintain accuracy of phasing.

A feature of the invention relates to a drive coupling between a motor and a scanning drum, including a slip-friction clutch having an element which can be selectively stopped, the said element being coupled to the drum by a special one-way latch whereby, under certain conditions, the drum can coast freely with respect to the clutch, and the phasing action is efiected on the stop arm and its disc which have relatively little inertia.

Another feature relates to a novel form of oneway positive drive coupling between a scanning drum and a driving motor.

A further feature relates to the novel organization, arrangement and relative interconnection of parts which cooperate to produce an improved phasing control for telegraph machines such as facsimile scanners and the like.

Other features and advantages not specifically enumerated will be apparent after a considera tion of the following detailed descriptions and the appended claims.

In the drawing which'represents one preferred embodiment,

Fig. 1 shows the general arrangement of the more important parts of the clutch, and the drum-driving and coupling mechanism according to the invention.

Fig. 2 is an end elevation of Fig. 1, along the dotted section line, and viewed in the direction of the arrows 2--2.

Fig. 3 is an end elevation of Fig. 1, along the dotted section line, and viewed in the direction of the arrows 33.

Figs. 4 and 5 are enlarged detailed views of the driving and coasting control latch shown in Figs. 1 to 3.

Referring to the drawing, the driving motor (not shown), is connected to the drive shaft I which carries at its right-hand end a slip-friction clutch 2. .This clutch may be of any well-known type comprising, for example, a set of three friction discs 2 and 3, which are appropriately fastened to shaft I; and an intermediate friction disc 4 which is not connected to the shaft but is driven by frictional engagement with discs 2 and 3. A detailed description of one preferred construction for the clutch, is given in applicationSerial No. 501,953, filed September 11, 1943, the disclosure of which application is expressly incorporated herein by reference. Firmly attached to member 4 is a rigid stop arm 5, which of the drum as it is rotating.

has an inclined trailing face 6. The stopping of disc 4 is controlled by the armature l of an electromagnet 8, armature I being pivoted at its upper end (Fig. 2) in the L-shaped frame 9 on which. the magnet 8 is mounted. A retractile spring it tends to hold the lower end of armature l to the left, and'in the path of'member 5, however, when" magnet 8 is energized, armature l is clear of arm '5. Magnet 8 is normally continuously energized thus allowing arm rotate with shaft I in the direction of the arrow (Fig. 2).

Arm when released, is adapted to engage the left-hand end of a latch H' which is pivotally mounted on a pin $2 in aslotted guide or stud l3 which is rigidly fastened to the drum driving plate Hi. The slot l5 in member l3 isinclined to correspond with the inclined righthand end of latch ll so that when these inclined surfaces are in contact as shown in Fig. 4, the latch ll extends perpendicularly to plate it. A spring it has one end attached to latch ii and the other end to 'inember lkand. it is coiled or biassed so that it normally holds latch. H in theposition shown in Fig. 4.

Plate [4 is'fastenedto the drum shaft i'i which is journalled at opposite ends in suitable ball bearing iii and is. An end thrust ball bearing 2c is located between the recessed right-hand end of shaft ll and the bearing plate 2!, the proper bearing pressure being obtained by a spring22 located between bearing plate 23 and a collar 2% fastened to shaft ll. This arrangement provides a frictionless thrust bearing which prevents any lengthwise vibration or oscillation The shaft ll carries the usual lead'screw 25 and its right-hand endis slotted at'zfi and isslidably keyed to scanning drum 2?, so that as shaft l1 turns, the drum 2'! also turns and advances along the shaft, depending upon the pitch of the lead screw thread. For a' detailed description of a preferred drum and lead screw arrangement, reference may be had to U. 5. Patent No. 2,138,784, the disclosure of which is expressly incorporated herein by reference.

With the arrangement as described, the drum 2'! can continue to rotate freely, even though the disc 4 and the arm 5 are held stationary by armature 1 during thephasing operation. This.

is so, because when the drum, as a result of its inertia, continues rotating, the latch H at its left-hand end (Fig. 5)-, strikes the arm 5 which is now stationary, with the result that latch I freely pivots around pin the drum. 1 If a phasing impulse is not received to energize magnet 8 during the interval required for the-drum to makeonecomplete revolution, the drumcontinues to rotate by reason of its inertia. The friction of the drum mounting is the drum will coast as many "as four or five-revolutions before coming torest. Should thephasing impulse be received while the drum iscoasting-armature I is attractedby-magnet 8 andreleases arm 5 for rotation with shaft l. w Arm 5 thereupon-gradually catches up on thecoasting latch ll because of the'gradual deceleration of the drum, until the latch actually engages arm 5 as shown-in Fig. 4. In this relation, the driving force of arm 5 positively rotates latch llcounter-clockwisearound pin'JZ (Fig. 4) to-cause a positive driving conneetion between shaft l and shaft ll. However, the loadvuponthe clutch and motor at this initial-contact is very-much-less-than it would be E2 without stopping,

if member 5 were required to start the drum from a standstill position. For example, if the drum is coasting at half its normal speed, the load on the clutch is only one-quarter of that required to accelerate it to the same speed as would be the case if the members 3 and 8 were always positively connected. It should be observed =that when the latch II is positively driving plate M, the frictional load of the drum and its bearings is sufiicient to provide back pressure against the member 5 so that the latch II is held against the said member 5 and thereby continues to drive the drum positively.

While one particular embodiment of the invention has been disclosed herein, it will be understood that various changes and modifications may be made without departing from the spirit and scope of the invention.

W hat I claim is:

l. A phasing arrangement for a telegraph apparatus such as afacsimile scanning drum comprising, a continuously running drivinginember for said drum, a-driving connection between said member and said drum, said connection including a device which can be stoppedto allow the drum to continuously coast with. relation to said driving member whilesaid device is stopped, said device when released allowing the driving member to impart positive driving force to the drum.

2. A phasing arrangement for a telegraph apparatus such as a facsimile scanning drum comprising, acontinuously running driving member, a scanning drum having substantial rotational inertia, adriving connection between said member and said drum including a stopping device and a one-way positivelatch couplin between said'driving member and said-drum to allow said drum-to continually coast with relation to said drivingmember while said device is operated.

3. A phasing arrangement for a telegraph device suchas a facsimile scanning drum, comprising a continuously running driving shaft, a driven shaft for the drum,-said drum having considerable rotational inertia and connected to said driven shaft, a slip-friction clutch between said two shafts having a member frictionally driven from said driving shaft, and a one-way latch'device between said member and said driven shaft for imparting a positive drive to said driven shaft but without permanent connection to said driving shaft, while allowing the driven shaft to coast continuously even when said member is stationary.

4. A phasing arrangement for a telegraph device such as a facsimile scanning drum, comprising a continuously running driving shaft, a driven shaft for the drum, a member frictionally driven from said driven shaft and drum, stopping means for said member to' cause said member to be stopped without stopping said driven shaft and to allow said driven shaft to coast freely and continuously even while'the said member is stopped.

5. A phasing arrangement for a telegraph device such as a facsimile scanning drum, compris ing a driving shaft, a driven shaft, a facsimile scanning drum connected to said driven shaft, a slip-friction clutch having a member which'can be stopped without stopping said driving shaft, a device connected to said driven shaft and having a pivoted arm adapted to beengaged by said member to impart positive driving force to th'e driven shaft, said arm allowing said driven. shaft and drum to-coast freelyand'continuously with respect to saiddriving shaft while said member isstopped.

6. A phasing arrangement for a telegraph device such as a facsimile scanning drum, comprising a continuously running driving shaft, a driven shaft for said drum, a slip-friction clutch having a member frictionally coupled to the driving shaft, a stop arm carried by said member, an electromagnet having means to engage said member to stop it without stopping said driving shaft, a driving plate fastened to the driven shaft, and a pivoted latch member extending from said plate into the path of rotation of said stop arm.

7. An arrangement according to claim 6 in which said pivoted latch member is pivotally mounted in a slotted guide extending perpendicular to said driving plate, said latch being normally spring-pressed so as to form an eflective elongation of said guide.

8. A phasing arrangement for a telegraph device such as a facsimile scanning drum, comprising a continuously running driving source for said drum, means to drive the drum from said source preliminarily to the receipt of a phasing signal, means to disconnect the drum from said driving source while allowing the drum to coast freely, and means responsive to the receipt of a phasing signal to control the connection of said driving source to said drum while the latter is coasting in the same direction as that of said driving source.

JOHN R. SI-IONNARD.

REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,329,077 Nichols Sept. 7, 1943 110,521 Waterbury Dec. 2'7, 1870 1,955,200 Millican Apr. 17, 1934 2,255,869 Ridings et a1. Sept. 16, 1941 2,047,863 Finch July 14, 19 6

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