US1387240A - Stroboscopic system - Google Patents

Description

R. E. COLLIS. STROBOSCOPIC SYSTEM.

APPLICATION FILED FEB.14. 1918.

Patented Aug. 9, MEE..

/mx/e/a Rayma/vdi CoH/Is.

naar

RAYMOND E. comers, or EAST onnNeE, New JERSEY, assrcnon 'ro weerman' ELEC- 'rnio COMPANY, mconrona'rnn, or New YORK, N. Y., A comona'rron or NEW YGREo STROBOSCOPIC SYSTEM.

Specification of Letters Patent.

Patented. Aug.. 9,1921..

Application led. February, 14.', 1918. Serial No. 217,153.

.To all whom it may concern: I

Be it knownthat l, RAYMOND E. COLLIs, a citizen of the United States, residin at East Orange, in the county of Essex, tate of New Jersey, have invented certain new `and useful Improvements in Stroboscopic- Systems, of which the following is a full, clear, concise, and exact description. f

This invention relates to systems for determining the rate or cyclic `frequency of periodic motion, and more particularly to stroboscopic systems for observing vibratory or rotatory motion.

The present invention is applicable in comprises an arrangement for rendering a moving body visible only at certain points of its path, as by throwing lightupon it at intervals or by observing it through moving apertures ln connection with such an arrangement, the present invention contemplates the use of characters or other markings placed at one or more points on a moving body in such avmanner that the characters or markings may, during certain predetermined speed relations with respect to moving apertures and the moving body, become intelligible to an observer.

This invention is illustrated diagrammatically in the accompanyin drawing in which only so much of a stro Oscopic system is shown as will be necessary to a clear understanding of the resent invention.

In the drawing, igure 1, is shown a vibrating means suitable for alternately obscnring and clearing an observing or sighting range. In Fig. 2 is shown a revoluble disk 011 which characters are placed in a manner to illustrate one embodiment of the invention, while in Figs. 3 and 4 are shown respectively alternate arrangements which may be substituted for the disk shown inv Fig. 2.

In describing this invention, a tuned fork,

indicated by the reference character 1 (Fig.l

1), is provided with a-slitted diaphragm on each of its prongs, and when vibrating the slits 3 and 4 register, one with the other, once during a complete vibra-tory cycle of the prongs. The fork may either be xed to a suitable support or held in the grasp of an observer in such a position that observation taken from a point indicated by thel vision symbol 5, as directed through the openings or slits A and 4,- will range or aline within a limited area or scope on the surface of a body 10 shown in each of the Figs. 2, 3 and L1, respectively. 1t will be understood that either one of the bodies 10 may be rotated on its axis 11 (by means not shown) and it will be apparent that during such rotation the numbers present in the circular paths 12 and 13 on the body Fig. 1 and the paths 12 to 17, Figs. 3 and e, would be unintelligible or entirely obliterated with respect to unaided or non-controlled visualizing of the disk. On'peering or gazing in alinement with the registering position of the openings 3 and 4, after-first setting the fork 1 in vibration, certain respective speed relations between a body 10 and the fork 1 will render corresponding ones of the figures clear and intelligible to an observer.

Although tuned forks employed for stroboscopic lobservations may be arranged in such a manner that the slits in the overlapping iianges or diaphragms may register,

one with the other, more than once during` each com'plet'e vibration of the fork, a visualizing ratio on the basis of a single opening ot the sighting range for each vibration of the fork will, for yconvenience of description, iirst be considered. The speed relation between such single acting fork and any combination of single or plural markings on the revolving bodies v10, together with the speed at which the body may be rotating, will perhaps be more readily `understood from a statement of this relation in the form of an equation. Accordingly, let T represent the time in seconds for an interval of one minute; R, the rate or number of Vibrations per second of the tuned fork 1; N, the number of different equidistant points at whichl a certain marking or character may appear on i a body while X represents the. number of revolutions perminute at which such body 10 must be revolving inorder that the marking or character may be rendered visibly intelligible. i rllhen, y '1 R T X Substituting values, for purpose of example 60x 10o e00 0 8 T 750 v 1n this instance the fork would be operating would be present Vat eight'diflerent equidisat a frequency of one-hundred vibrationsper second, while the character to-be visualized revolutions,- when that number `ofrevolu tions correspond with' a time interval of one minute. As well understood in connection with stroboscopic determinations, the

' described condition of periodic motion, with respect to the fork l and the disk 10 will render the numberr 7 50 clearly intelligible to an observer.

For the purpose of a second illustration, let it now be assumed that withthe same fork it is desired to discern a marking which appears at sin different equidistant points around the disk 1 0. Accordingly,

eo ico ecco llt will be seen that the number 1000 appears at six di`erent points on the disk 10, therefore, this number will be visible to an observer siX times per revolution of the disk or 6000 times during 1000 revolutions, when the revolutions take place in the time of one minute. An observer may therefore lclearly read this number, which will indicate that the disk is being operated at the rate of4 1000 revolutions per minute.

. As a further example, let it be assumed that it is desired to employ the same fork for making determinations with respect to markings which appear at four different equidistant points on the disk 10. By means ofthe same formulae,

60 X100 6000 T-T- 1500 The number 1500 is present at four different points on the disk and will, therefore, become intelligible to an observer four times 'thousand times durin during eaclifrevolution of the disk or six l1000 revolutions,

whenA the revolutions ta e place evenly during a period of one minute.

llt`rom` the foregoing description, it wlll be clear that if the disk 10 be started from a condition of rest and rotated at an accelerating rate and the tuned fork liset into vibration, in any convenient manner, observation taken through the range permitted by the slits 3 'and el will lir t become aware of the `speed 750, follow d successively by an indication ofthe speeds 1000 and 1500, respectively. lin a converse manner if negative acceleration or decrease of speed is now applied to the disk, the speeds 1500, 1000 and 750 would successively become visibleto an observer. llt will, therefore,be obvious that with the present system the fact that the rate of a periodic inotion may be read directly without. the necessity of keepingv in mind the ratio or factor byiwhich determinations taken from arbitrary markings must be translated, ren- ?ders the present method etiicient, reliable and convenient.

lln connection with systems of motion, it is frequently more desirable to directly determine the working factor or the output rate of a machine or mechanism rather than to ascertain the speed rate of any of its moving parts, in order to avoid the process of translating such speed rate into the actual working or output capacity of the system.

` graphic equipment for the present assumed case would be capable of properly responding to various speeds which the distributers may attain, it will be considered that an average of ten revolutions of the distributer part, 'which may be driving the disk 10, represents a transmission rate ofone word. rllherefore, at a speed of 7 50 revolutions per minute, the rate of transmission would be 75 words per minute, for 1000 revolutions per minute, 100 words per minute would be transmitted, and for a speed of 1500 revolutions per minute 150 words per minute would be handled.

ln keeping with such transmission rates, the second circular path 13 on the' disk l0 lic is provided with eight markings for the word speed, six markings for the'100-word speed and four-markings which correspond. with the 150 `lwords' per minute'speed. In bringing the distributors at`.-.-,remote telegraphic vstations intoA 's'ynchronism, one with another, it is therefore only necessary that the attendants have information as to the number of words per minute which it will be necessary to adhere to in order that unison of operation may be arrived at and maintained. To this end observations as may be taken by way of the sighting slits in the fork 1 may be directed onto the path 13 -of the disk 10, and a speed controlling means (not shown) suitably adjusted to maintain the speed of the distributor at any 'desired one of the word transmission rates,-

the number 75 being rendered readable when the speed is 750 revolutions per minute which corresponds with the 75 words, per minute rate of sending, and in a similar manner the number indicating 100 words per minute would be readable at the corresponding speed of 1000 revolutions per minute, while the number signifying 150 words per minute would be readable for the corresponding speed of 1500 revolutions perminute. In regulating the operation of the distributers on the basis of the rateof thetelegraphic transmission, as described, the

markings in the path 12, which correspond with the revolutions per minute of the distributers, would lnot ordinarily be required and therefore could be dispensed with in the handling of such service.

It will be pointed out that duringthe timey the speed of 1500 revolutions per minute would be readable, as described, the number 7 50 would also be readable, this phenomenonv being due to the fact that the number of points at which each of these sets of numbers appear on the disk are in the ratio of an even multiple, one with the other. In the case of the. different speed indicating numbers employed f r purpose ofv illustratiing the principle of tl e s stem, a lower number would be disregar ed when readable with a higher number, as the latter number would be the true speed. In practice, the speed rates would not ordinarily cxtend'over such a wide range, and are more likely to be in the relation of a five, point, asin point and a seven point series of groupings on the' disk 10. For such combinations no double readings would be likely toresult, as the ratio between the different groups would be fractional and not in the proportion of even multiples. In order to avoid a more involved description which would have been necessitated by employing speeds which would work out fractionally, the present, even multiple speeds were-used since they are equally applicable lin conveying a. clear understanding of the features ofthe system.

it would result that one point would be common to two dijerent number groups, a numgroup of numbers from which-one point or occurrence has been omitted, a slightly.grayber may be omitted from one group. Under such condition it has been found that for av l ish flashing will'oecur during the time the v speed of the system is such that the numbers of thisgroup are otherwise distinctly readable.

Referring to the matter of the frequency bf the tuned fork 1, it will be understood that if theapertures 3 and 4 are arrangedl to register, one with the other, more than once during va complete yibration of the-fork,

the sighting range with respect to the disk 10 would require' that'they vbe used as multipliers in arriving at the speed observed.

:For example, a fork operating at the rate of 50 vibrations per second and clearing the sighting range twice per vibration, would give the same result as that attained by the fork 1 operating at 100 vibrations per second and clearing the sighting range only once during. each vibration.

The disk shown in Fig. 3 of the drawing may be considered to be the same as the disk 10 (Fig. 2) lexcept that the several groups of speed and working-rate numbers are arthat such additional ,frequency in clearing ranged in respectively diderent circularpaths 12 to 17, lying at diil'erent respective radial distances from the center of the disk.

By this a'rrangeinent no vdouble readings can possibly occur, as already described, and it is also more convenient in certain situations In Fig. 4 a revoluble drum or cylinder y pis shown which may be substituted for the disk shownv in ,either Fig. 2 or Fig. 3, num

bers corresponding with di'erent speeds or the working rate of a system of motion being spaced at eq'uidistant points in paths 12 to 17 which .11e around the face of the drum as indicated.

Although numerals have, for convenience of description, been employed in marki the stroboscopm disks, it will be understoo that letters, words `or any other type of characters or markings may be employed in substitution of the numerals without departing from the spirit of this invention, and also that a character may be shown yat only one. point on the moving body instead of a plurality of points as shown forcenvenien of description.

What is claimed is:

1. A. stroboscopic system comprising a moving body carrying a plurality of sets of numerals, the numerals of each set being equally spaced and of the samevalue, the numerals of the respective sets being spaced at different distances apart and of different values, and means for rendering any of the numerals of any of the sets legible during the rotation of said body when the speed thereof correspondsto the value of the numerals in one of such sets.

2. A stroboscopic system comprising a i moving body carrying a plurality of sets of numerals, the numerals of each set being equally spaced and of the same `Value, the numerals of the respective sets being spaced at different distances apart and of dierent values, and a vibrating member for renderf ing any of the numerals of any of the sets legible during the movement of said body when the speedtherer.2 corresponds to the value of the numerals in one of the sets.

3. A stroboscopic system comprising a moving body carrying a plurality or sets of numerals, the numerals of each set being equally spaced and of the same value, the

numerals of the respective sets being spaced at different distances apart and of dierent values, a vibrating member having an aper ture, and means :tor opening and closing said aperture'in response to the vibration of said member, whereby the numerals in any of said sets are rendered legible when the rate of speed of said body corresponds to the value of the numerals in one of the sets.

d. A.. stroboscopic system comprising a moving body carrying a plurality of sets of numerals, the numerals of each set being equally spaced and of the same value, the numerals of the respective sets being spaced at dierent distances apart and of different values, and means for detecting the relation between the spacing and the value of the numerals, whereby the 'speed of rotation of' said body is indicated automatically.

5. A stroboscopic system comprising a moving body carrying a. plurality of sets of numerals, the numerals of each set being equally spaced and of the same value, the numerals of the respective sets being spaced at di'erent distances apart and of different values, and a vibrating member for detecting the relation between the spacing and the value of the numerals, whereby the speedofi rotation of said body is indicated automatically. v n

lin witness whereof, l hereunto subscribe my name this 6th day of February, A. D., 1918..

nitrite-nn n contre.

Images