GB2089988A - Length measuring instrument with tracing unit and switch arrangement - Google Patents

Abstract

A hand-held instrument (21) having a length measuring wheel (43) and a tracing unit (71) has the tracing unit (71) slidably carried by the housing (21) and acting to operate a switch (101) fixed on the housing. The switch may be a miniature snap action type actuated by the slidable tracing unit (71) either directly or indirectly through an intermediate adjustable spring lever arm (190) or may be in the form of a reed switch actuated by a permanent magnet carried by the sliding tracing unit (71). The wheel (43) is carried in a removable nose element (33). <IMAGE>

Description

SPECIFICATION Length probe with tracing unit and switch arrangement This invention relates to an apparatus for taking length measurements, as well as if desired, counting and more particularly to a combination length probe a tracing unit and switch arrangement in which a switch is actuated as a function of the depress/release action of the tracing unit.

It is desirable for various reasons to provide a length measurement probe with switch means thereon actuable when the unit is pressed against a surface the length of which is to be measured.

Such an arrangement may have various uses, including preventing the registration of false length measurement counts when the probe is not being used or is being laid down and picked up and as a dual function length measuring probe and item counting unit in which each actuation of the switch is used to initiate a count pulse.

According to this invention, a portable handheld combination length probe, tracing unit and switch arrangement comprises a length probe unit and a tracing unit secured together as a single portable hand-held probe and tracing unit; switch means carried by the length probe unit or the tracing unit, the tracing unit having a longitudinally slidable body; spring means resiliently biasing the tracing unit body towards a first position, but permitting movement of the body against the spring to a second position; and, switch actuator means for actuating the switch means, in response to the movement of the tracing unit.

Two examples of a portable hand-held combination length probe, tracing unit and switch arrangement in accordance with this invention will now be described with reference to the accompanying drawings; in which: Figure 1 is a perspective view of a first example; Figure 2 is a perspective view of the length probe body or housing of the first example; Figure 3 is a perspective view of the marker or tracing unit housing of the first example; Figure 4 is a perspective view of the nose of the length probe; Figure 5 is a side elevation of the length measurement wheel; Figure 6 is a fragmentary partial sectioned view of the probe arrangement in the first example; Figure 7 is a perspective view of the switch of the first example with part of the associated holder/retainer clip shown in dotted lines for clarity;; Figure 8 is a partial section taken on the line 8-8 shown in Figure 6; Figure 9 is a perspective view of the front retention clip; Figure 10 is a fragmentary section of a second example; Figure 11 is a perspective view, partly shown in dotted lines for clarity, of the switch and holder/retainer clip of the second example; and, Figure 12 is a fragmentary section of a modification of the second example.

In the first example, a portable hand-held probe 11 includes a length probe 21 with a marker or tracing unit and switch arrangement 71.

The length probe 21 has a housing or main body 23 onto which marker/switch housing or main body 73 is removably secured. A nose body 33 fits in manually removable light press fit within a bore 27 formed in length probe housing 23, and carries a length measuring wheel 43 freely rotatably mounted thereon in a wheel slot 39 as by a pin 37a press fit in bore 37 and freely passing through wheel bore 47.

Housing 73 has a longitudinal concave surface 73a mating with the outer convex surface of housing 23, and is removably secured thereto through the medium of front and rear retainer clips 95 and 97. Front retainer clip 95 is disposed within a slightly enlarged shouldered counter bore 73bf at the forward end of bore 73b of housing 73, and extends through an anchor slot 29 formed in the forward open bore end of housing 23. The retainer clip 95 is spread apart at its free ends to form a retention foot 95b which is secured in place within counterbore 27b by the nose body 33. In addition, front retainer clip 95 serves in conjunction with indexing flat 38 on nose body 33 to angularly position the wheel support nose, thereby orienting the axis of wheel 43.

The rear end of housing 73 is secured to housing 23 by rear retention clip 97 which has a curved section 97a disposed in rear counter bore 73br of housing 73 and extends through slot 25 in housing 23. A retention foot 97b is formed on retainer clip 97, and extends rearward of slot 25 along and in engagement with the wall of bore 27 to thereby anchor the rear end of housing 73 to housing 23.

Wheel 43 has transverse holes formed about and inboard of its periphery at angularly equidistant intervals, which holes 45 are successively brought into alignment with transverse bore 34, 34a extending through the one-piece integral nose body 33. An infrared LED and infrared-sensitive phototransistor are disposed within bore 34 on opposite sides of wheel slot 39 in facing relation, and their lead wires LEDL and PTL extend through longitudinal side slots 35 formed in nose body 33 and connecting with bore 34. This invention is not directed to the details of the wheel movement pickup per se, and accordingly such are not shown or further described in detail.

A composite lead wire 201 extends through a small bore hole at the rear of housing 23 and carries the lead wires PTL and LEDL from the phototransistor and LED respectively, as well as the lead wires from a switch 101 later to be described.

Mounted within bore 73b in housing 73 is a tracer or marker unit having a fixed outer shell 93 removably press fit within bore 73b and in-rolled to form a retention lip 92a at its forward end. A slide tube 83 fits in free sliding relation within a plastic bushing 85 press fit within body shell 93.

Slide tube 83 is threadedly connected with a marker- or tracer-holding chuck split collet 89 which has normally readilly resiliently outspread jaws retained in gripping relation with a marker or tracer element 81 a, such as a pencil lead or a tracer ball element, by radially inward acting cam action thereon by longitudinal engagement and rearward movement thereof within collet retainer 91 with its cam end surface 91a. Collet 89 is resiliently biased rearwardly against collet retainer 91 and its cam end surface 91 a through the medium of compressed compression spring 84 which acts between the rear face of retainer 91 and a mid-flange 83a formed on slide tube 83.

Pressing slide tube 83 forward against the action of spring 84 will enable radially outward selfmovement of the jaws of collet 89 to thereby release or enable insertion and/or adjustment of the marker, tracer, or other inserted element 81 a held by collet 89.

Spring 84 is of substantially greater strength than rear compression spring 86 which extends in compressed relation between mid-flange 83a and the forward face of bushing 85, so as to assure firm gripping of the marker or tracer element 81 a or the like and assure reliability of actuation of switch 101 through rearward movement of the marker or tracer element 81. The weaker rear spring serves to return the slide tube 83 with its marker or tracer element 81 a or the like to the forward quiescent position shown in Figure 6, after each depression and release of rearward pressure on the marker unit through contact with a hard surface.

Switch 101 is disposed adjacent slide tube 83 and its extension formed by rear handle 87 which is removably press fit thereon. This switch location enables the switch 101 to be actuated as a function of sliding movement of the slide tube 83 and its marker or tracer element 81 a or the like. To this end, handle 87 has an annular inclined rearwardly facing cam surface 87a formed thereon and engageable with an intermediate spring lever arm 109, movement of which acts to depress exposed insuiated actuator 107 protruding from the insulated case 103 of switch 101. The intermediate spring lever arm is secured as by brads 1 09a on switch case 103 and enables ease of adjustment of the longitudinal position at which the slide tube and handle are disposed when actuation of switch 101 is effected. Such adjustment may be accomplished through bending of spring arm 109.

Switch 101 is mounted on rear retainer clip 97 as by transverse brads 108 (see Figure 7), and the retainer clip 97 and switch 101, thus form a separably removable composite dual purpose unit.

Switch 101 is shown in its normal condition with its snap action contact arm 105 in normally closed condition with one contact, to be opened through rearward movement of marker or tracer unit 81 with its marker or tracer element 81 a, collet 89, retainer 91, slide tube 83 and handle 87 having an annular cam surface 87a, which handle cam surface 87a effects a lateral camming action on spring lever arm 109 to thereby move actuator 107 and open the normally closed contacts of switch 101. The switch 101 may be thus connected as a simple normally closed single pole switch, and used to provide automatic disablement of passage of signals form the wheel movement pickup arrangement to a counter when the switch is thus normally closed.

The switch may also have alternative use, such as by employing it as a count pulse switch, where the operator desires to check off a number of points on a drawing or the like, and the marker will be depressed once for each checked point. In such case the switch 101 may be wired from only the normally open contact and the snap action contact arm thereof, if so desired, such that depression of marker 81 would effect closure of switch 101, rather than opening as in the preceding use example. Or both contacts and the contact arm may be wired in and used for a given circuit configuration, if so desired. For this reason the switch connector posts CP are all shown having lead wires, although in a given use instance only a selected two connector posts CP may be effectively wired in.

Figures 10 and 11 illustrate a modification of the invention, in which a magnetically actuated reed switch 201 is employed in lieu of the mechanically actuated snap-action switch 101 of Figures 1-9. Rear retention clip 297 replaces retention clip 97, and serves both to anchor the rear end of housing 73 and to locate the reed switch 201 which may be of conventional construction. Reed switch 201 is cradled in a plastic support 203 bradded to retainer clip 297 as at 208. A ring magnet 287a is positioned in a ring groove 287r on handle 287, and serves to actuate the reed switch as a function of longitudinal sliding movement of the slide tube 83.

A further and preferred modification is iliustrated in Figure 12, in which a reed switch 301 is actuated by a magnet 387a carried by the handle 387. In this embodiment the reed switch 301 is secured, as by adhesively bonding, within a slot recess 73c formed in housing 73, with lead wires extending through a slot 325 formed in housing 23 and collected within composite lead wire 201.

Magnet 387a is mounted within the bore of handle 287 rearward of slide tube 83. This magnetically actuated reed switch modification lends itself to precise positioning and control of the switch and its actuating magnet and to simplicity and reliability of manufacture.

Claims (27)

1. A portable hand-held combination length probe, tracing unit, and switch arrangement comprising a length probe unit and a tracing unit secured together as a single portable hand-held probe and tracing unit; switch means carried by the length probe unit or the tracing unit, the tracing unit having a longitudinally slidable body; spring means resiliently biasing the tracing unit body towards a first position, but permitting movement of the body against the spring to a second position; and, switch actuator means for actuating the switch means, in response to the movement of the tracing unit.

2. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 1, in which the switch means is a self-return snap-action switch having an actuator and in which cam means are provided on the slidable tracing unit for actuating the switch means through movement of the actuator as a result of movement of the slidable tracing unit.

3. A portable hand-held combination length probe, tracing unit, and switch arrangment, according to claim 2, also including an intermediate bendable spring lever arm located between the cam means and the switch actuator for moving the actuator by engagement of the cam with the spring lever arm.

4. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to any one of claims 1 to 3, in which the tracing unit has a chuck collet and a longitudinally slidable chuck collet retainer within which the collet is selectively slidable and which also includes further spring means resiliently holding the collet in a normally closed condition within the retainer, a slide member slidably carrying the collet shoulder means between the ends of the slide member and against which the spring means and the further spring means act in opposing directions, a stationary bush slidably carrying the slide member, and stop means in front of the collet retainer for limiting forward movement of the collet retainer, the first mentioned spring means being arranged between the shoulder means and the bush and being substantially weaker than the further spring means, the further spring means being in front of the shoulder means and acting in compression between the shoulder means and the collet retainer and being stronger than the first mentioned spring means, so that rearward axial pressure on the collet effects rearward movement of the slide member compressing the weaker rear spring means, whilst forward axial pressure on the rear of the tracing unit compresses the stronger forward spring to thereby push the collet through the collet retainer.

5. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 4, in which the member is a slidable tube secured to the collet.

6. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to claim 4 or 5, in which the tracing unit further includes a tubular shell within which the collet retainer is slidably mounted, the tubular shell having an inturned forward end section forming the stop means for the collet retainer.

7. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to any one of claims 4 to 6, in which the switch actuator means comprises an annular cam surface on the rear portion of the slidable tracing unit.

8. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to any one of claims 1 to 7, in which the length probe and the tracing unit each have a housing section which remains stationary relative to one another, and a forward retention clip adjacent the front end of the tracing unit housing extends through a slot in the tracing unit housing into engagement with an anchor portion of the length probe.

9. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 1,2 or 3, in which the length probe and the tracing unit each have a housing section which remains stationary relative to one another, the length probe housing having a slot therein, and a rear retention clip adjacent the rear end of the tracing unit and extending through the slot in the length probe housing, the rear retention clip having a rearwardly extending retention foot extending into the length probe housing and behind the slot to longitudinally and laterally anchor the rear end of the tracing unit housing to the length probe housing.

1 0. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 9, in which the switch means and rear retention clip are secured together as a discrete separable unit.

11. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to claim 9 or 10, in which a forward retention clip adjacent the front end of the tracing unit housing extends through a slot in the tracing unit housing into engagement with an anchor portion of the length probe.

12. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to any one of claims 8 to 11, in which the length probe housing section has a hollow bore therein open at its front end, and a nose body -slidably and removably located within the front end of the bore of the length probe housing section and forming the anchor portion of the length probe, the nose body having an undercut indexing flat which engages the retention clip in a substantially angularly anchored fashion.

1 3. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to claim 1, in which the length probe and the tracing unit each have a housing section which remains stationary relative to one another, in which a retention device secures the housing sections together, with the switch means and a rear retention device being secured together as a discrete separable unit, in which the switch means comprises a magnetically actuated switch, and in which magnetic field generating means on the longitudinally slidable body of the tracing unit is movable into and out of a switch-actuating position relative to the switch as a result of the back-and-forth longitudinal sliding movement of the slidable body.

14. A portable hand-held combination length probe, tracing unit and switch arrangement, according to claim 13, in which the switch means is a magnetically actuable reed switch, and in which the magnetic field generating means is a permanent magnet on the longitudinally slidable body of the tracing unit.

1 5. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 1, in which the switch means comprises a magnetically actuated switch, and in which magnetic field generating means on the longitudinally slidable body of the tracing unit is movable into and out of switch-actuating position relative to the switch as a result of the back-andforth longitudinal sliding movement of the slidable body.

1 6. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 15, in which the magnetic switch means is fixed in position with respect to the length probe.

17. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 1 5 or 16, in which the magnetically actuated switch is a magnetically actuable reed switch.

18. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 15, 16 or 17, in which the magnetic field generating means is a permanent magnet.

19. A portable hand-held combination length probe, trading unit and switch arrangement according to claim 18, in which the permanent magnet is a ring magnet.

20. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 1 8 or 1 9 in which the length probe has a body with an externaliy communicable recess formed therein and within which the magnetically actuated switch is mounted.

21. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 20, in which the recess has a bottom wall closely adjacent the path of movement of the permanent magnet, and in which the magnetically actuable reed switch is secured within the recess against the bottom wall.

22. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 18 or 19, in which the tracing unit has a rear handle, in which the permanent magnet is carried by the handle.

23. A portable hand-held combination length probe, tracing unit, and switch arrangement according to claim 22, in which the permanent magnet is generally laterally centred within a central cavity in the handle.

24. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 18 or 19, in which the slidable tracing unit includes a main slide tube and a rear handle, the rear handle being a press fit onto the main slide tube, the spring means extends about the main slide tube, and in which the permanent magnet is secured to the rear handle.

25. A portable hand-held combination length probe, tracing unit, and switch arrangement, according to claim 24, in which the rear handle has a central bore within which the permanent magnet is mounted.

26. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 25, in which the rear handle has a ring groove, and in which the permanent magnet is a ring magnet mounted in the ring groove.

27. A portable hand-held combination length probe, tracing unit and switch arrangement according to claim 1, constructed substantially as described with reference to the accompanying drawings.