IL31417A - Vernier-type measuring device - Google Patents

Description

3-n 013'BD ηττ» ipnn Vernier-type measuring device DONALD HATCH C. 29693 The invention relates to a new and improved vernier dial system.

The invention is "based on the principle of the conventional vernier, a simple form of which consists of two parallel scales, one of which is free to move along the edge of the other. One scale is divided into a number of equal parts, usually ten, and a second scale is also divided into ten equal parts, each of which is shorter than the parts into which the first scale is divided by 1/lOth of the length of the parts of the first scale. In this way, relative movement of the two scales can be read to an accuracy of one hundredth part of the scale length by Observing which pair of scale lines are co-linear.

According to the invention, there is provided a vernier dial system comprising at least a first and second juxtaposed dial members, at least one of which is rotatabie with respect to the other about an axis common to the two members, said dial members collectively carrying an indexing means, a first circular scale indicia defining a normal scale, second circular scale indicia defining a radially expanded version of said normal scale, third circular scale indicia defining a vernier scale adapted for operable juxtaposition with said second circular scale indicia, said first circular scale indicia and said indexing means each being carried by respectively different ones of said dial members and said second circular scale indicia and third circular scale indicia each being carried by a respectively different one of said dial members.

The members may, for example, take the form of superimposed straight slides or circular discs or of cylinders located one within the other. The markings on the lower or inner scale may be white or highly reflective lines on a dark background, the markings on the upper or outer scale being transparent markings l ight-colored background.

Embodiments of the invention wi l l now be described , by way of example only, with reference to the accompanying drawings 1n whic :- F1g. 1 shows two linear scales adapted to be super-Imposed one upon the other to form a devi ce for measuring l inear displacements Fig. 2 is a perspective view of a device for measuring small angular displacements , such as a control knob on a sensi tive instrument; Fig. 3 shows the two scales of the Fig. 2 device; and Figs . 4 to 6 show three ways in which the invention may be applied to a screw micrometer.

Referring to the drawings , the embodiment shown in Fig. 1 comprises * an upper scale 5 and a lower scale 6 which may be arranged, in a manner not shown , to be super-imposed one on the other for relative sl iding movement. The upper scale is divided into ten equal parts by lines 1/llth inch apart and marked wi th the numerals 0 - 9 as shown. The lines are transparent and surrounded by a dark background and the upper half of the scale is also transparent. The lower scale is divided into equal parts by lines 1/1 Oth inch apart marked with numerals as shown. The l ines are white on a dark background, and the numerals are visible through the transparent upper half of the top scale 5 when the latter is placed over the scale 6.

In use of the device to measure smal l l inear displacements , the left hand end of the lower scale 6 is placed against one end of the object to be measured and the upper scale 5 is sl id along scale 6 to the right ti l l the zero reading of the scale 5 is alongside the other end of the object.

The length of the object can then be quickly and easi ly read off to the nearest 1/100th inch by reading from the bottom and top scales in turn as fol lows . The zero of the upper scale in the drawing is positioned between the 4 and 5 marks so that the object is between four and five tenths of an inch long. The markings on the lower scale wi l l al l be hidden by the upper scale except where markings on the two scales are exactly aligned , 1n which case the lower marking wi l l show clearly due to the contrast between the mark an inch to give the length of the object. In the drawing , a l ine of contrast wi l l appear at the number 6 marking on the top scale so that the total length is 0.46 inches.

It wil l be appreciated that as only one clear line of contrast will appear at any one position, the length can be very qui ckly read by glancing at the bottom and top scales in turn.

Fig. 2 shows a devi ce for measuring smal l angular displacements.

The devi ce could be used as a control knob for a variable resistance or other instrument requi ring fine adjustment, and comprises a body 7 having a lower scale marked on the top face 8 thereof , and an upper scale marked on a disc 9 secured to a shaft 10 and control knob 11 for rotation relative to the body 7.

As shown i n Fig. 3, the lower scale has ten radial lines marked around Its perimeter at 33° intervals and numbered from 0 to 9. These markings are whi te on a black background and are visible through transparent l ines on a black background marked on the disc 9. There are twelve of such lines on the disc 9 spaced 30° apart, and numerals from 1 to 10 also spaced at 30° are marked i n the center of the lower scale being visible through the central part of disc 9 , which is of clear plasti c material . The upper disc carries an arrow 12 at a l ine thereon representing zero position and the zero l ines of the i nner and outer lower scales are both on the same radius.

The pri nciple of operation is identical to that of the Fig, 1 embodiment, When the disc 9 is rotated, the arrow 12 indicates on the Inner lower scale the number of 30° Intervals covered, e.g . in the drawings it is located between l ines 3 and 4 of the centre scale. In addition , the l ine 5 of the lower outer scale shows through the second l ine from zero of the upper scale (see arrows) . Thus the angular position of the upper scale relative to the lower scale is 3 x 30° + 5 x 3° = 105° from the initi al rest position.

The coinciding markings on the upper and lower scales wi l l provide a clear l ine of contrast at the No. 5 line of the lower scale , so that the readi ng can be qui ckly and easi ly made.

Fig. 4 shows one manner of applying the invention to a screw micro of ten markings spaced circumferential ly around the body and numbered from 0 to 9 as shown. These markings extend axially beneath the thimble 16, which has a further series of markings in the form of circumferential slits 17 through which the circumferential markings on the body can be seen. In this way, readings to 1/1000th inch can- be made, the first digit being read from the axial scale, the second from the thimble scale, and the third appearing as a line of contrast through the thimble scale where a mark on the circumferential body scale is aligned with a slit in the thimble. In the drawing the reading is 0.501 inch. The slits 17 could, of course, be replaced by transparent lines on a dark background.

Fig. 5 shows an alternative arrangement in which the circumferent al body scale of the Fig. 4 embodiment is replaced by a scale on a sliding collar 20 which moves along the body as the thimble 16 is rotated. The scale on the collar extends beneath the thimble and the markings are visible through slit markings 17 on the thimble. In the drawing the instrument reads 0.423 inch. Again the slits 17 could be replaced by transparent lines on a dark background. Fig. 6 shows a further manner of applying the invention to a micrometer using an arrangement similar to Fig. 3, but with the lower inner and outer scales fixed to the body and divided into ten parts and the upper scale rotatable with the thimble and also divided into ten parts. In the drawing the instrument reads 0.462 inch. The transparent markings on the upper scale could, of course, be replaced by slits.

It will be appreciated that many modifications may be made without departing from the invention. For example the numbers and spacings of the markings can be varied depending on the units involved and the degree of accuracy required. Generally, the ratio of spacing of the lines will be in accordance with the relationship spacing of lines on one scale _ N spacing of lines on other scale ~ (N + N/x) where x = Number of divisions on the one scale. This applies whether N is in markings on either scale can be varied in any desired practicable manner without departing from the invention.

The colors of the markings and backgrounds can be varied widely provided a clear contrast line is obtainable. Moreover, it may be desirable in addition to having one full line, clearly visible to have parts of the lines on either side visible at the same time. If this is not done and the measurement falls between two divisions no indication at all will be visible as to the last digit without moving the upper or outer scale slightly. A similar result can be obtained by tapering the marking lines such that at an exact reading the whole tapered marking is visible, the thin end being extinguished half way between readings, but parts of the thick ends of two adjacent markings being visible at all times except exact readings.

It will also be appreciated that the invention may be applied in many different fields, for example to protractors, aircraft instruments, machine tool adjustments, electrical measuring instruments, knobs or dials for any device or instrument requiring fine adjustment and indeed, in any situation where accurate measurement of or movement through a linear or angular displacement is required.

Claims (15)

31417/2 CLA tm kMJA iWC J Ail ft/In iif?

1. A vernier dial system comprising at least a first and second juxtaposed dial members, at least one of which Is rotatable with respect to the other about an axis common to the two members, said dial members collectively carrying an Indexing means, a first circular scale Indicia defining a normal scale, second circular scale Indicia defining a radially expanded version of said normal scale, third circular scale Indicia defining a vernier scale adapted for operable juxtaposition with said second circular scale Indicia, said first circular scale Indicia and said Indexing means each being carried by respectively different ones of said dial members and said second circular scale indicia and third circular scale Indicia each being carried by a respectively different one of said dial members.

2. The vernier dial system as claimed In Claim I wherein dial members comprise a lower dial member and an upper dial member relatively rotatable about said axis and having dial faces transverse to the axis and positioned In operable relative axial proximity, said dial member carrying said normal scale having said normal scale circularly disposed on Its dial face adjacent the axis with satd first scale Indicia being distributed cl rcumferentlal ly, the dial member not carrying said normal scale having said Indexing element cooperable with said normal scale, the dial member having said second scale on its dial face being circularly disposed thereon and of greater radius than the normal scale and having indicating elements distributed circumferential ly at the same angular spacing of the normal scale and thereby constituting said expanded scale relative thereto, and the dial member not carrying said expanded scale having said third scale circularly disposed on Its dial face In visual cooperative position relative to said second scale 31417/2 ; and having Indicating elements distributed circumferential ly and spaced dissimilarly to those of said second scale and thus constituting said vernier scale.

3. The vernier dial system as claimed In Claim 2. and Including a mounting member, and wherein the lower dial member Is fixedly mounted thereon and the upper dial member Is rotatably mounted thereon.

4. The vernier dial system as claimed in Claim 2 and Including a mounting member, and wherein the upper dial member Is fixedly mounted thereon and the lower dial member Is rotatably mounted thereon.

5. The vernier dial system as claimed In Claim 2 wherein both dial members are of the same size, and the expanded and vernier scales are of substantially the same radius and in register In axial direction, and the registered scale on the upper dial member. Includes voids constituting the indicating elements and through which the Indicating elements of the registered scale on the lower dial member are exposed.

6. The vernier dial system as claimed in Claim 5 wherein the registered scale on the upper dial member Includes a series of dark segments cl rcumferential ly spaced apart to form said voids therebetween, and the Indicating elements in the registered scale on the lower dial member are light in color and In high contrast to said dark segments.

7. •7. The vernier dial system as claimed in Claim 5 wherein the registered scale on the upper dial member includes a series of dark segments circumferential ly spaced apart to form said voids therebetween, and the Indicating elements In the registered scale on the lowe>r dial member are of reflective character and In high contrast to said dark segments. 31417/2

8. The vernier dial system as claimed in Claim 5 wherein the voids are apertures formed by cut-out portions In the upper dial members.

9. The vernier dial system as claimed in Claim 5 wherein the upper dial member is of transparent material, the registered scale on the upper dtal member includes a series of c I rcumferential ly spaced segments of opaque material applied to the transparent material, and the voids are formed by uncovered portions of the transparent material between said segments.

10. The vernier dial system as claimed In Claim 5 wherein the Indicating elements In both the registered scales are In the form of straight radial lines.

11. The vernier dial system as claimed in Claim 5 wherein the Indicating elements In the registered scale on the upper dial member are In the form of straight radial lines, and the Indicating elements In the registered scale on the lower dial member are of wedge shape with their wide portions of substantially the same width as the indicating elements In the registered scale on the upper dial member.

12. The vernier dial system as claimed in Claim 2 In which the Indicating elements in the vernier scale are more widely spaced than those In the expanded scale, and the dial members are relatively rotatable In opposite directions.

13. The vernier dial system as claimed In Claim 2 In which the Indicating elements in the vernier scale are more closely spaced than In the expanded scale, and the dial members are relatively rotatable In opposite directions.

14. The vernier dial system as claimed in Claim 2 wherein the indicating elements in the normal scale and the vernier scale both Include "0" Identifying the beginning Indicium, and the ' "Ts 214X7/2 are In radial alignment.

15. The vernier dial system as claimed in Claim I, wherein the ratio of angular spacing of indicia on said normal and vernier scales are in accordance with the relationship Spacing on one scale = N , Spacing on other scale (N + N) X where N Is in units of measurement of said spacing, and X is the number of divisions on said one scale. For the Applicants DR. J&TBBSLD COffiT AS PARiHERS By:,