Inconspicuous Ranging Device For Golfers

Abstract

An inconspicuous optical-triangulation ranging device for golfers typically comprising, in the various embodiments, a composite of a pentaprism and one or more simple prisms for observing and comparing three views, a view of the green, a reference view, normal to the first view, of a feature of the landscape, and a view, deviated by a known angle, of one of the first two views; structures for hinged attachment of the device to a cap brim and for rotation of the prism assembly to look to the right or left are disclosed.

Description

This invention relates generally to optical apparatus and method for triangular ranging, and particularly to means and method for finding the range of the flag on a golf course green from the position where a golfer's ball lies on the fairway, to facilitate the selection of a properly lofted club with which to hit an approach shot, as with an iron club. The most critical ranges vary from about 60 to 180 yards.

Ranging devices are available in trade but existing devices are embarrassing because their use is conspicuous to other players. Ranging by means of the device I have invented has a prime merit that it is inconspicuous.

Although ranging devices are not allowed in official play, they are very useful for a golfer who is just learning the game; or for a more experienced golfer when he is becoming familiar with a strange course, where distances are often deceptive.

Objects, therefore, of my invention are to provide inconspicuous, accurate, ranging devices especially adapted for golfing, which are easy to use and which are economical to manufacture.

I embody my invention typically in a unitary compound prism providing means for obtaining simultaneously a direct view of the working field or view toward the green, a comparison view of a field substantially at right angles to the direction of the working view, with one of the two above mentioned fields being a split view with component fields separated laterally by a known small angle.

Other objects, advantages and features of my invention will become better understood from the following description, including the drawings in which:

FIG. 1a, b, and c are three views of a prism assembly in one embodiment of my invention;

FIG. 2a is a schematic plan view of the FIG. 1 embodiment in use on a golf course;

FIG. 2b, c, d, and e are representations of the fields of view obtained in the use illustrated in FIG. 2a;

FIG. 3a, b, and c are three views of a prism assembly in a second embodiment of my invention;

FIG. 4 is an elevation, partly in section, of an embodiment of my invention affixed to a golfer's cap;

FIG. 5a, b and c are three views of a prism assembly in a third embodiment of my invention;

FIG. 5d and e are representations of fields of view through the FIG. 5 embodiment;

FIG. 6a, b and c are three views of a prism assembly in a fourth embodiment of my invention;

FIG. 6d and e are representations of fields of view illustrating use of the FIG. 6 embodiment and

FIG. 7 shows a further embodiment of my invention affixed to a cap.

As shown in FIG. 1, in three orthogonal views, a, b and c, my device in a preferred embodiment 10 includes a small penta prism 12 with one of the 22.5.degree. faces 14, 16, covered with a half-reflecting, beam splitter coating 18, and in addition with the upper and lower halves of this face 14 covered with two laterally disposed simple prisms 20 and 22, with apices adjacent the base of the penta prism. The covering prisms are cemented in optical contact with the pentaprism with Canada balsam or other optical cement. One of the covering prisms is a compensating 22.5.degree. prism 20, made of glass of substantially the same index of refraction N as the pentaprism so that a direct view through the penta prism is undeviated. The other covering prism 22 is made either over-, or under-, compensating, so that the direct view through one 90.degree. face 26 of the penta-prism and this other prism to the eye E of the observer is deviated by, say, 1/15 radians. For N = 1.5 this other prism will have a prism angle not 22.5.degree. but approximately 15.degree., or 30.degree.. A 30.degree. prism is shown in the drawings as an example. The other 22.5.degree. face, 16, of the penta prism, is covered with an opaque reflecting layer 24. The other 90.degree. face, 28, of the pentaprism, is normal to the light received through it from a reference field at right angles to the direction of the direct, or working view.

FIG. 2 is a diagrammatic illustration of the use of my invention. The compound of prisms 10 is shown exaggerated, and the deviation angle, 1/15 radian, through the 30.degree. covering prism 22 relative to the 22 1/2 prism 20, is also exaggerated.

The assembly of prisms is small and, as will be seen, may be worn attached to the bill of a golfer's cap on a hinge, so that it may be flipped down in front of one eye with the ease of a sun shade. Otherwise the wearer's hands are not needed for ranging.

The golfer, facing the flag, with the prism assembly in front of one eye, tips his head down or up to see the superposition of flag and lateral landmark, here taken to be the trunk of a tree, T, through the upper, 22 1/2.degree. covering prism, or through the lower 30.degree. prism.

With his head tipped properly down he will see through the upper prism 20 and face 26 of the assembly the lateral landmark T superimposed, or nearly so, on the direct view, as in FIG. 2b. As his landmark he will select a tree trunk as shown, or a fence post, or a feature on a house, or some such object that is approximately at 90.degree. to the direction of the flag F. If the best object does not quite coincide with the flag, as in FIG. 2b, the golfer will make a lateral sidestep to the right or left as required and thus adjust coincidence between the object and the flag F as in FIG. 2c. The half-reflecting and full reflecting coatings 18 and 24 on the 22.5.degree. faces 14 and 16 of the penta prism 12, being at an angle of 45.degree. in respect to each other, effect a 90.degree. rotation of the lateral view that is independent of any slight turning of the golfer's head to one side or another as he faces the flag F. Also, the deviation of 1/15 radian is independent of such slight turning of his head.

On tipping his head so that his view is through lower prism 22 the golfer will then see the flag apparently moved to the left of the landmark, as in FIG. 2d.

Now the golfer makes and counts S side steps to the left until he sees the landmark T superimposed on the flag F through the lower half of the face 26 of assembly 10, as shown in FIG. 2e. On tipping his head to look through the upper prism again he will see the flag apparently moved to the left of the landmark, as it may have been originally.

The range, R, is determined from S by a multiplying factor, M, which is the reciprocal of the angle 1/15 radians:

R=MS

Although the superposition of the lateral field is independent of small rotations of the prism complex about a vertical axis, the interpretation of the number of lateral side steps, S, as range, is dependent on whether the shift S is in a line nearly perpendicular to R. This is because any violation of a perpendicular shift adds or subtracts to the prism deviating angle, 1/15 radians, by which we determine the range. Achievement of this perpendicularity is sensitively dependent on the distance to the landmarks and it is, for this reason, best to choose the most distant landmark that is available. If, in a particular instance, a more distant, appropriate landmark is on the left of the fairway, it may be used by turning the prism complex top-for-bottom.

Also, if the golfer finds an appropriate land mark on the right of the fairway to be nearer that more closely coincides with the flag in the lower part of the view than in the upper, he may adjust to this coincidence first and make the measuring side steps to the right for the second coincidence; the same procedure holds for the opposite side.

If the composite of prisms is hand-held instead of worn on a headpiece, it is necessary to hold with the left hand when the reference view is taken to the right, and vice-versa.

If S is the number of side steps, and fractions thereof, the interpretation of this number to determine the range is obtained by a mental multiplication of S by 15. But a simpler interpretation, that only involves subtraction, if the golfer has only a week-end competence, with a game like my own, is to select the club number, C, by subtracting S from 14:

C = 14 - S

Table 1 gives the side steps (or yards) S; range R, in forward steps; and club selection, C.

TABLE I

S R C = 14 - S 5 75 9 6 90 8 7 105 7 8 120 6 9 135 5 10 150 4 11 165 3 12 180 2

for the first times that I used my invention, I kept records of S; R estimated from R = MS; and of the actual R, obtained by stepping off the distance to the flag. I found that the estimated ranges and stepped ranges were in agreement to 5 percent. Subsequently, I found that my skill grew rapidly with experience, and that I could achieve this same precision with another composite prism with a greater magnification, M = 30. With this M = 30, only half as many side-steps were required, making the device still easier to use covertly. In order to accommodate such growth of skill, a further embodiment of my invention, as shown in FIG. 3, is a composite prism assembly 300 with three covering prisms of angle: 22.5.degree. as before; and 22.5.degree. + .theta. and 22.5.degree. - .phi., respectively numbered 320, 322, and 330 in FIG. 3. This makes three magnifications available; the smaller one, say M = 15, is appropriate for the beginner in use of the device; or for short ranges after he has acquired skills. The larger one is used with a greater inconspicuousness after skill has been acquired because fewer side steps are required.

FIG. 3 exemplifies this device with three covering prisms, 330, 320, 322, with:

.theta. = 7.5.degree., as before, yielding M = 15

.phi. = 4.degree., yielding M = 30

And if the successive side steps are between coincidences in the views through (22.5.degree. + 7.5.degree. = 30.degree.), and (22.5.degree. - 4.degree. = 18.5.degree.) prisms; then the third magnification available is

M = 30/3 = 10

This last M = 10 is convenient on occasion for ranging chip shots.

The penta prism in FIG. 3 is preferably somewhat larger than that of FIG. 1, say 1.5 .times. taller; but this is not necessary. Although, in the beginning, the golfer may find some difficulty in locating the chosen landmark for the second coincidence when the field of view is small, the skill at doing this grows rapidly.

After the club selection has been decided, the prism is flipped on its hinge back up against the bill of the golfer's cap and held there by some such spring device as that shown in FIG. 4.

In FIG. 4 cap C has a typical bill B, shown partly broken away, to which an embodiment of my invention is attached.

The embodiment consists of prism assembly 10 which is secured within the flanges of channel-section ring 32 in front of the prism assembly by three shoulder tabs 34 affixed to a housing 33 holding the prism assembly 10. A light rotative fit is provided between the prism assembly and ring so that the prism assembly can be rotated but is retained by friction at the position to which rotated. The protrusion of the housing affords a grip for rotating the prism assembly.

Lateral cutouts 48, 50, in the ring provide for viewing the reference field to either side, according to the rotative position of the prism assembly.

The ring 32 is secured by an arm 36 to notched pivot-member 40 which in turn may be removably attached by a clip or thumb screw to a bracket 52 in the underside of the cap brim B after play has begun. Two notches, 42, 44, which successively engage a spring detent 38 fastened to bracket 52 hold the device in position for viewing, or stowed away inconspicuously in the curvature of the cap brim during play as indicated by the dashed outline.

The purpose of apertures 64 and 66 above and below the prism assembly will become evident in reference to the description of a later embodiment.

FIG. 5 shows an embodiment 500 of my invention which is similar to the FIG. 1 embodiment except that no half-reflecting surfaces are involved; it employs (FIG. 5b) a fully reflecting central section 518, such as may be accomplished by deposit of a thin opaque film of silver, beneath a portion of the 22.5.degree. and 30.degree. covering prisms, 520 and 522. Because this embodiment does not require a beam-splitting coat over the full 22.5.degree. face 514 of the penta prism 512, but only this full reflecting coat over the central third of that face, it is cheaper to manufacture.

FIGS. 5d and e show how this embodiment is used. The flag F, in full view, is juxtaposed, rather than superimposed on the landmark, here a fence post P. The advantages of this embodiment are that the juxtaposed fields are substantially twice as bright as the previously described superimposed fields, and that this embodiment is cheaper to manufacture because it is easier to produce full reflecting coatings than beam-splitter coatings.

FIG. 6 shows a further embodiment 600. Here both 22.5.degree. faces 614 and 616 are made fully reflecting. A 7.5.degree. prism 656 is put over half of the 90.degree. penta prism face 628 through which the lateral field is viewed. This embodiment is used by juxtaposing fields rather than superimposing them. The direct view of the flag is seen past one of the parallel faces 660 or 662 of the pentaprism, that is, over the top or bottom of the prism composite 600, and the side-stepping from one juxtaposition to another (FIGS. 6d and 6e) is interpreted exactly as has been described above. In this instance the multiplying factor for a 7.5.degree. covering prism is again M = 15.

The holder illustrated in FIG. 4 serves as well for this embodiment, since there are apertures 64 and 66 above and below the prism assembly.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. For example, the embodiment illustrated in FIG. 1 could be cut along the section line indicated by A--A to form two smaller coacting devices as in FIG. 7 at 70 and 72. The golfer would flip-down first one and then the other to secure his range.

Again, although simple prisms of 22.5.degree. and other specific apex angles are described above for use with penta-prisms, it is to be understood that these are effective angles, described in context in which the index of refraction is assumed to be the same for all prisms. If the material of a "22.5.degree." prism has other than the same index of refraction as the pentaprism with which it is used, an apex angle will be chosen to produce the same result as if it had the same index as the pentaprism and an apex angle of 22.5.degree..

Claims

I claim:

1. An inconspicuous ranging device for golfers, comprising pentaprism means for simultaneous observation and comparison of a reference field of view and a working field of view substantially normal thereto, and further prism means partially covering one face of the pentaprism means for simultaneously observing a portion of one said field of view through the pentaprism means at a known angle other than normal to the other said field of view, the further prism means being integrally arranged with respect to the pentaprism means.

2. A ranging device as recited in claim 1, and means for rotating all said prism means about an axis passing through a 90.degree. face of the pentaprism means.

3. A ranging device as recited in claim 2, wherein the first said prism means comprises a pentaprism.

4. A ranging device comprising: prism means for simultaneous observation and comparison of a reference field of view and a working field of view substantially normal thereto, and further prism means for simultaneously observing a portion of one said field of view at a known angle other than normal to the other said field of view, the first said prism means comprising a pentaprism, the pentaprism having means for reflecting light transmitted to one 22.5.degree. face by one 90.degree. face, thereby providing for said observation of the reference field of view; and the further prism means being in optical contact with a portion of said one 90.degree. face of the pentaprism.

5. A ranging device as recited in claim 4 wherein the further prism means comprises a simple prism with the base thereof proximate the apex of said pentaprism and the width thereof covering a portion of the width of said one 90.degree. face.

6. A ranging device as recited in claim 4, wherein the means for reflecting light comprises coatings on both 22.5.degree. faces.

7. A ranging device as recited in claim 5, and holding means for the prism means including means for rotating the prism means about an axis passing through a 90.degree. face of the pentaprism.

8. A ranging device as recited in claim 7, said holding means having an aperture therethrough past a parallel face of the pentaprism in a direction normal to a 90.degree. face of the pentaprism.

9. A ranging device as recited in claim 8, said holding means including articulated means for mounting the ranging device to the underside of a cap brim.

10. A ranging device as recited in claim 4, wherein the further prisms means is separate from the first said prism means.

11. A ranging device comprising: prism means for simultaneous observation and comparison of a reference field of view and a working field of view substantially normal thereto, and further prism means for simultaneously observing a portion of one said field of view, the first said prism means comprising a pentaprism, the pentaprism having means for reflecting light transmitted to one 22.5.degree. face, by one 90.degree. face, to the other 22.5.degree. face and thence through the other 90.degree. face, thereby providing for a said observation of a reference field; the further prism means comprising plural prisms in optical contact with a portion of said other 22.5.degree. face of the pentaprism.

12. A ranging device as recited in claim 11 wherein the plural prism means comprises at least two prisms laterally disposed on said other 22.5.degree. face of the pentaprism with the apices of said at least two prisms adjacent the base of the pentaprism parallel to the thickness thereof, and wherein said at least two prisms have discrete apex angles.

13. A ranging device as recited in claim 11 wherein one of said at least two prisms has an apex angle of 22.5.degree..

14. A ranging device as recited in claim 13 wherein the apex angle of the another of said at least two prisms differs from the apex angle of the first said prism by seven and one-half degrees, thereby providing for at least two transmitted views of said working field for observation through said other 90.degree. face, with the direction of one view being undeviated and the direction of the another view being deviated by one-fifteenth radian.

15. A ranging device as recited in claim 12, wherein the means for reflecting light from said other 22.5.degree. face comprises a beam-splitter coating.

16. A ranging device as recited in claim 12, wherein the means for reflecting light from said other 22.5.degree. face comprises an opaque reflective coating disposed beneath proximate portions less than the whole width of each of two said laterally disposed prisms.

17. A ranging device as recited in claim 13, and an additional prism similarly disposed with the first said at least two prisms on the 22.5.degree. face of the pentaprism, the additional prism having a discrete apex angle, and the 22.5.degree. degree prism being between the additional prism and one of said at least two prisms.

18. A ranging device as recited in claim 11, and holding means for the prism means including means for rotating the prism means about an axis passing through a 90.degree. face of the pentaprism.

19. The method of determining the distance to an object by visual observation comprising the steps of:

a. viewing the object to be ranged: b. juxtaposing at the first said view a view of an object at right angles to the direction of the first said view; c. laterally offsetting one of the aforesaid views by a known angle; d. compensating the lateral offset by laterally moving the point of observation; and e. comparing the compensating lateral movement with a known ratio based on said angles, thereby determining the distance to said object.