FIELD OF THE INVENTION

This invention relates to a method and apparatus for improved control of drilling and the like apparatus. A particular application of the invention is to hand-held drilling apparatus, in which the provision of improved means for controlling the attitude of the apparatus, would be an advance. Other applications of the invention include other power driven drilling, boring, and the like kinds of apparatus where there does not otherwise exist a convenient means (such as an adjustable external frame) on which both the apparatus and the workpiece being worked on can be mounted and thus controlled in terms of relative attitude.

BACKGROUND OF THE INVENTION

Prior proposals in relation to drilling and the like apparatus as discussed above include U.S. patent application publication US2009/0260239 Al (Cerwin), published October 22, 2009. In the Cerwin publication there is disclosed apparatus of the kind discussed above in which laser means provides visual assistance with manual control of the drilling apparatus. The laser means comprises a laser which rotates with the chuck of the drilling apparatus and traces, as perceived by the human eye if rotation is fast enough, on the workpiece a circular or distorted circular path, whose shape is used to determine angular and translational information with respect to the relative attitudes of the drilling apparatus and the workpiece. For the purposes of this application it should be noted that the term attitude includes the relative angle and relative position of the apparatus to the workpiece.

The apparatus disclosed in the US Cerwin specification is subject to the limitation that the circular or distorted circular (that is elliptical) laser path produced on the workpiece is not easy to interpret when actually using the apparatus in the workplace, because in practice the hand-held drilling apparatus inevitably lies in the line of sight for the drill-user viewing the laser path, with the result that the user cannot see all of the pattern or trace, or indeed enough of the laser pattern or trace in order to be able accurately to interpret the results. The point in this regard is that drill-guidance is a question of interpreting very minor differences of profile in the laser pattern, trace or display so as to enable accuracy of drilling attitude to be ensured. Other examples of the prior art include US 6,328,505 and US2007/0030486.

SUMMARY OF THE INVENTION

Therefore some means is needed to improve the interpretation of the laser (or the like) pattern, trace or display produced by a rotating chuck (or the like) in such a situation. Another desirable improvement in such apparatus would be to provide a convenient means for controlling the depth of penetration into a workpiece of the apparatus otherwise than by mere judgement on the part of the user.

An object of the present invention is to provide a method and apparatus applicable to drilling, boring and the like apparatus offering one or more improvements in relation to the shortcomings of the prior art discussed above, or generally.

According to one aspect of the invention there is provided a method and apparatus applicable to handheld drilling, boring and the like apparatus. The method and apparatus enables improved guidance of such apparatus in use. The method and apparatus comprises rotary laser or-the-like visible beam generating means adapted to be mounted on a chuck or related rotary tool-mounting of the apparatus, for rotation therewith about the axis of drilling, boring (or similar work on a workpiece), of the apparatus. In use, the beam produces a circular or distorted circular (for example elliptical) trace or pattern or display, as perceived by the human eye if rotation is fast enough, on or in relation to the workpiece to be drilled, bored or the like. The trace or pattern or display is adapted by the provision of visual-aid means to assist interpretation of its profile, position or form, by the user.

One embodiment of said visual aid means comprises intersecting crosshairs. The cross hairs may intersect on the axis of rotation of the drilling, boring or the like apparatus. The cross hairs may be virtual cross hairs, which are perceived by the user as a result of other aspects of the visible portions of the drill-control display or trace, or the cross hairs may be actually-visible cross hairs which are specifically produced by apparatus provided therefor, such as laser-imaging-means adapted to generate such cross hairs, in association with the remainder of the drill-guiding pattern or trace or display.

Another embodiment of said visual aid means provides gaps, for example diametrically-aligned gaps, in the circular or distorted circular (for example elliptical) pattern or display or trace produced by the apparatus. In the case where the gaps are disposed at ninety-degree intervals around the circular or distorted circular pattern or display, and a user is able to see at least slightly more than one half of the entire circle or distorted circle of the pattern, trace or display, including two diametrically-aligned such gaps, such user can mentally construct or visualise orthogonally-intersecting cross hairs by virtue of the aforesaid gaps. To put it another way, the provision of the gaps in the otherwise continuous trace produced by rotating laser-or-the-like rotating energy-emitting devices, enables the user mentally to construct or visualise virtual cross hairs, each such hair commencing at its one of the circumferentially- spaced gaps in the trace. Each such cross hair extends inwards from its associated gap, towards the other cross hair, and the cross hairs intersect on the drilling axis. Alternatively to the visualisation by the user of virtual cross hairs, as aforesaid, another embodiment of the invention provides actually visible cross hairs by use of user-adjustable sighting means align- able with a selected drilling or boring or other work-location axis on the workpiece so as to project, for example, laser-generated cross hairs at said location, whereby, in use, said cross hairs co-operate with the circular or distorted circular pattern or display, as more fully described below.

Thus, envisaged embodiments of the invention provide visual-aid means to assist assessment or evaluation of the laser-generated circle or distorted circle/ellipse provided by drilling (or the like) guidance means, such as disclosed in the above Cerwin specification. The embodiments offer means whereby a user of hand-held drilling, boring and the like apparatus, is assisted in such assessment or evaluation by associated modifying visual aid means. Accordingly, the problem that part of the circle or distorted circle/ellipse generated by chuck-mounted laser-imaging means, as disclosed in the Cerwin specification, is more or less unavoidably-obscured for the user by the body of the drill, is alleviated by the provision of means to inform the user as to the proportion of the circle or distorted circle which is within the user's field of vision at any given time. Thus, for example, in the situation where the user has within his/her field of vision only a little more than half of the total trace produced by the laser, and therefore cannot look at the circle as a whole, which (were it available) would make it relatively easy to assess whether it is an undistorted circle, the user can (with this more limited view of the 'circle') assess with relative confidence the visible semi-circle, because the user can see exactly the limits of the semi-circle, and visualise it as a known proportion of a distorted or undistorted complete trace accordingly.

It is envisaged that less than a semi-circle (180 degrees), for example a quadrant (90 degrees) or an intermediate value may be sufficient for evaluation purposes in certain circumstances, for example where visual-comparison diagrams can be provided alongside or otherwise conveniently-visible for the user. Thus although the proportion used for the purposes of the invention will usually be one quarter or one half (of a complete circle), one third may be sufficient in some cases, though the shortness of the curved periphery makes it more problematic to be confident of correct assessment on an instantaneous basis, as is often needed. The provision of proportion-indicating means enables the user to assess, on the basis of any known (sufficiently-long) proportion of a complete circle, the circularity of the trace produced by the laser-or-the-like imaging means, accordingly.

Putting the visual-assessment process in terms of vector-movement: at the end of a semi-circle or quadrant, which (in an embodiment of the invention) is known to be such by its identifying gaps or cross hairs, the user can visualise a virtual circumferentially-moving point on the laser (or the like) trace, approaching the known end of the sector or quadrant or semi-circle, and at that location it changes direction from (imagining the defined end as being on a clock-face at 'a quarter-to-the-hour) towards the 'nine o'clock' position, to away from it. Such an instantaneous change of direction, is readily identifiable, and thus its visualisation assists interpretation of the trace.

Turning now to consider statements and features of the invention in less-informal terms, there is provided, in a first aspect of the invention, a method of detecting a non-orthogonal attitude in hand- held article processing apparatus comprising:

a) presenting said article processing apparatus to an article to be processed while hand-holding said article processing apparatus;

b) causing rotary laser or-the-like visible beam generating means mounted on a chuck or related rotary tool-mounting of the apparatus, for rotation therewith about the axis of drilling, boring or the like of the apparatus, to produce a circular or distorted circular pattern or display on or in relation to the workpiece to be drilled, according to the attitude of same relative to the workpiece; and c) using said circular or distorted circular pattern or display to interpret the attitude to be adopted by said apparatus, and modifying or not the attitude of said hand-held article processing apparatus accordingly;

characterised by

d) providing in association with said circular or distorted circular pattern or display, proportion- indicating means, adapted to assist the visual assessment of said pattern or display by the user, whereby the user can more readily visually or mentally assess the proportion of said circular or distorted circular pattern or display which is visible to him/her during use, whereby, in consequence it can likewise be decided whether or not said circle is distorted and thus whether the article processing apparatus is orthogonal to its workpiece.

In an embodiment of the first aspect of the invention as set-forth in the preceding paragraph, the method may be further characterised by said step of providing said proportion-indicating means adapted to provide gaps in said circular or distorted circular pattern or display at known circumferential-proportion-intervals, such as one-half or one quarter, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her between said gaps, and whereby, the user can likewise decide whether or not said visible circle-portion is distorted and thus whether the article processing apparatus is orthogonal to its workpiece.

The method of the preceding paragraph's above-defined first aspect of the invention may be further characterised by said proportion-indicating means providing cross hairs at known circumferential- proportion-intervals of said display or trace, to co-operate with said circular or distorted circular pattern or display, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her by visual assessment of the quadrants or the like thus formed, as opposed to mere sectors of a circle or ellipse.

The method of the above-defined first aspect of the invention may be further characterised by said proportion-indicating means providing both cross hairs to co-operate with said circular or distorted circular pattern or display, and gaps in said pattern or display, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her by visual assessment of the quadrants or the like thus formed, as opposed to mere sectors of a circle or ellipse.

Considering now a less-informal definition of an apparatus aspect of the invention, there is provided apparatus for detecting a non-orthogonal attitude in hand-held article processing apparatus comprising:

a) rotary laser or-the-like visible beam generating means mounted on a chuck or related rotary tool- mounting of the apparatus, for rotation therewith about the axis of drilling, boring or the like of the apparatus, to produce a circular or distorted circular pattern or display on or in relation to the workpiece to be drilled, according to the attitude of same relative to the workpiece; and b) said circular or distorted circular pattern or display being interpretable as to the attitude to be adopted by said apparatus, whereby the user can modify or not the attitude of said hand-held article processing apparatus accordingly;

characterised by

c) providing in association with said rotary laser or-the-like visible beam generating means, proportion-indicating generating means, adapted to assist the visual assessment of said pattern or display by the user, whereby the user can more readily visually or mentally assess the proportion of said circular or elliptical pattern or display which is visible to him/her during use, whereby, in consequence it can likewise be decided whether or not said circle is distorted and thus whether the article processing apparatus is orthogonal to its workpiece.

The apparatus of the last-preceding paragraph may be further characterised by said proportion- indicating generating means, provided in association with said circular or elliptical pattern or display- generating means, and adapted to assist the visual assessment of said pattern or display by the user, being adapted to provide gaps in said circular or distorted circular pattern or display at known circumferential-proportion-intervals, such as one-half or one quarter, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her between said gaps, and whereby, the user can likewise decide whether or not said visible circle-portion is distorted and thus whether the article processing apparatus is orthogonal to its workpiece.

The apparatus of the last preceding paragraph may be further characterised in that the proportion- indicating generating means, which is provided in association with said circular or elliptical pattern or display-generating means, and is adapted to assist the visual assessment of said pattern or display by the user, is adapted to provide cross hairs to co-operate with said circular or distorted circular pattern or display, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her by visual assessment of the quadrants or the like thus-formed solid bodies (or entire sub-bodies) as opposed to mere sectors of a circle or ellipse.

Alternatively to matters defined in the last preceding paragraph, said proportion-indicating generating means, provided in association with said circular or elliptical pattern or display-generating means, and adapted to assist the visual assessment of said pattern or display by the user, may be adapted to provide both cross hairs to co-operate with said circular or distorted circular pattern or display, and gaps in said pattern or display, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her by visual assessment of the quadrants or the like thus formed, as opposed to mere sectors of a circle or ellipse.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of hand-held drilling apparatus (the hand holding it being omitted to enable the whole apparatus to be seen), in use in relation to a workpiece to be drilled;

Figure 2 shows a plan view of a laser trace, pattern or display produced by an embodiment of the invention, and which is interpretable by the user in terms of showing an orthogonal attitude (or not), accordingly;

Figure 3 likewise shows another plan view of a laser trace, pattern or display produced by another embodiment of the invention, and which is likewise interpretable by the user in terms of showing an orthogonal attitude (or not), accordingly; and

Figure 4 shows a further plan view of a laser trace, pattern or display produced by another embodiment of the invention, and which is again interpretable by the user in terms of showing an orthogonal attitude (or not), accordingly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated in Figure 1 of the drawings, a method of detecting a non-orthogonal attitude in handheld article processing apparatus 10 comprises presenting said article processing apparatus 10 to an article 12 to be processed or workpiece while hand-holding said article processing apparatus 10 during such processing.

In this embodiment, the article processing apparatus is in the form of an electrically-powered drill 14 comprising the usual hand-grip 16, operating trigger (not seen), main body 18 housing a drive motor, base 20 housing a rechargeable battery, an adjustable tool-receiving chuck 22 adapted to receive and grip a drill bit 24 for rotation about a drilling axis 26.

In this embodiment, workpiece 12 is in the form of a plank 28 of wood having side edges 29 and end edges 30. Of course innumerable other workpieces may be worked on by apparatus 10, and the invention is applicable to certain other power driven drilling, boring, and the like kinds of apparatus where there does not otherwise exist a convenient means (such as an adjustable external frame) on which both the drilling etc apparatus and the workpiece being drilled etc can be mounted and thus controlled in terms of relative attitude.

Rotary laser or-the-like visible beam generating means 32 is mounted on chuck 22 for rotation therewith about the axis 26 of drilling, to produce a circular or distorted circular pattern or display 34 on or in relation to workpiece 12 to be drilled, according to the attitude of same relative to the workpiece, as will be described below. The circular or distorted circular pattern or display or trace 34 is used to interpret the attitude adopted by drill 10, and modifying or not the attitude of said handheld article processing apparatus accordingly.

Beam generating means 32 is connected to a source 36 of energising electro-motive-force or electrical potential difference, whereby to cause the laser beam to be produced, as follows. E.m.f. source 36 comprises a slightly outwardly-tapering collar 38 formed integrally (or separably if more convenient from a production point of view) with the main body 18 of drill 10, and housing a non-rotatable internal magnet assembly (not seen) extending around drilling axis 26. Mounted radially inwardly of the magnet assembly and on the driven rotatable central shaft (not shown) of drill 10 for rotation with chuck 22 about axis 26, and likewise not seen in Figure 1 because hidden by collar 38, is a ferromagnetic conductor extending axially with respect to drilling axis 26, and positioned to intersect and cut (as it rotates) the magnetic field from the magnet assembly, thereby to generate the above- mentioned e.m.f. to energise the laser beam generating means 32.

As thus-far described, it will be understood that this embodiment operates to produce, in use, pattern, display or trace 34 on workpiece 12 while drill bit 24 drills into same. The user interprets trace 34 so as to determine whether the drill bit is drilling orthogonally to the workpiece, or not, as will be described below.

In accordance with the invention, this embodiment provides, in association with circular or distorted circular pattern or display 34, visual-aid means comprising proportion-indicating means, adapted to assist the visual assessment of said pattern or display by the user, whereby the user can more readily visually or mentally assess the proportion of said circular or distorted circular pattern or display which is visible to him/her during use, whereby, in consequence it can likewise be decided whether or not said circle is distorted and thus whether the article processing apparatus is orthogonal to its workpiece.

The aforesaid visual-aid proportion-indicating means adapted to assist the visual assessment of the pattern or display 34 by the user, comprises in this embodiment, providing gaps 40, 42 and 44, 46 in said circular or distorted circular pattern or display 34 at known circumferential-proportion-intervals, in this case at 90 degree or quarter-circle intervals, whereby the user can more readily visually assess the proportion of said entire circular or distorted circular pattern or display which is actually visible to him/her between said gaps, and whereby, the user can likewise decide whether or not the visible circle-portion is distorted and thus whether drill 14 is orthogonal to its workpiece 12.

In this latter regard, concerning visual assessment of the circularity of the trace 34 provided on workpiece 12, it needs to be understood that the problem with which the invention grapples is that the laser trace needs to be assessed visually orthogonally, otherwise the assessor (the user) is inherently introducing into the assessment process exactly the limitations which the invention is intended to reduce or eliminate. And hence the user positions him/herself behind the drill, and part of the trace is obscured by the drill body. Hence the need to assess the trace on the basis of only a part thereof.

The gaps 40, 42 and 44, 46 in the trace 34 are provided by the above-described laser beam generating means 32 by virtue of a feature of the construction thereof now to be described. Within collar 38, the non-rotatable internal magnet assembly (not seen) extending around drilling axis 26 is provided in the form of magnet segments, spaced-apart in accordance with the gaps 40, 42 and 44, 46 in trace 34, that is to say the gaps are at 90-degree or quarter-circle intervals and thus are arranged in pairs which are diametrically-aligned. Accordingly the magnetic fields produced by the magnets are likewise reduced in the spaces between the magnets. These latter fields extend, of course, around the magnets within the collar 38, and thus are cut by the ferro-magnetic conductor which is located immediately radially within the magnet assembly and is connected to laser beam generating means 32, and hence the e.m.f output from its opposite ends to the beam generating means correspondingly varies, whereby the gaps in its trace 34 seen at 40, 42 and 44, 46 are produced in use.

Figure 2 shows the trace, pattern or display 34 viewed orthogonally (as opposed to the 'three- quarters-perspective' view seen in Figure 1), and in Figure 2 there has not been shown the interposition, between the user (holding the drill) and the display 34, of the bulk of the drill main body 18 which, during conditions of normal every-day usage in a workshop or the like, can easily have the result that the user finds him/herself, while trying to view the display at right-angles to the workpiece 12, unable to see much more than half of the display.

Hence, imagining that little more than, shall we say, the upper-half of display 34 in Figure 2 were visible, it can now be seen that the user has to decide, usually fairly rapidly, and on the basis of rather limited information, as to whether the visible upper half of the trace 34 is or is not part of a true circle - in the latter case, the decision would be that a degree of elliptical form had been detected. Accordingly, and in accordance with the invention, by the provision of the gaps 40, 42 at diametrically- opposed positions (only one, 46 of the other pair of aligned gaps being visible in the described instance), the user can more readily visually assess the proportion (in this instance, the upper half) of the entire circular or distorted circular pattern or display 34 which is actually visible to him/her by visual assessment of the quadrants (all four being identified in Figure 2 as 48, 50, 52, 54, and the relevant two being 52 and 54) defined by these gaps, as opposed to assessment of a sector of a circle or ellipse (that is a mere line), were the gaps not present.

In this embodiment, it will be noted, there are also provided, as part of the visual aid means, assisting interpretation of trace 34, intersecting horizontal and vertical cross hairs 56, 58 respectively. The crosshairs intersect on the axis 26 of rotation of the drill. An aspect of the invention which may require a degree of user training, is that the cross hairs 56, 58 may be virtual cross hairs, which are perceived rather than actually seen by the user, as a result of the known proportions of the visible portions of the drill-control display or trace 34. Alternatively, and preferably, the cross hairs 56, 58 are actually- visible cross hairs which are specifically produced by apparatus (not shown) provided therefor, such as laser-imaging-means adapted to generate and project a beam showing such cross hairs on workpiece 12, in association with the remainder of the drill-guiding pattern or trace or display 34.

In use of the above embodiment, the user utilises the trace 34 to assess whether or not the trace is circular, and for orthogonal drilling with respect to workpiece 12, seeks to maintain circularity of the trace at all times by appropriate adjustment of the angular attitude of drill 10, having regard to the visual aids provided in relation thereto. The embodiment of Figure 3 is otherwise constructed and arranged and operates exactly as the embodiment of Figures 1 and 2, except that there are provided two laser traces, namely trace 34 as described above and a second trace or display 60, disposed radially-inwardly of trace 34, and having a diameter of approximately 0.6 times that of trace 34. Figure 3 is numbered to correspond with Figures 1 and 2 in respect of outer trace or display 34 and its associated features such as cross hairs 56, 58 and gaps 40, 42 and 44, 46. Second trace or display 60 serves to supplement trace 34 visually for the user, in the sense of reinforcing the defined visual-aid effect by virtue of the co-axial and hence co-operative relationship between the traces having the visual effect of assisting the appraisal by the user of the curvature of the displays and hence of distinguishing between circularity and ellipsoid format. Trace 60 has gaps 62, 64 and 66, 68 corresponding to and exactly aligned with the gaps 40, 42 and 44, 46. Cross hairs 56, 58 in Figure 3 extend through the aligned pairs of gaps 40, 62; 42, 64; 44, 66; and 46, 68.

Second trace or display 60 is provided by a second laser or-the-like beam generating means (not seen in Figure 3) mounted on chuck 22 for rotation therewith at a position such as to balance, at least partially, the weight-effect of the off-centre positioning of the first beam generator 32. In a first version envisaged, the spacial relationship of beam generating means 62 and 32 is at radially-spaced- apart positions, with generator 62 disposed inwardly of generator 32, by a radial distance corresponding to the radial spacing of traces 60 and 34. Thus in this first version envisaged, both beam generators generate beams, as in the case of the single generator of Figure 2, which are disposed purely axially with respect to drilling axis 26, and thus are unaffected by variations in the proximity of drill 10 to workpiecel2 and of the extent of penetration of the latter by drill bit 24.

In a second version of the second laser-or-the-like beam generating means (not seen in Figure 3), envisaged, the two beam generating means mounted on chuck 22 are at the same radial distance from the axis 26, and thus can weight-for-weight counterbalance each other's rotational effect, and the radial separation of the traces is caused by disposing the beam from the second beam generator at a slightly non-axial inclination, so as to achieve the illustrated separation of the traces. However, the inclination of the beam from the second generator with respect to axis 26 has the effect that its trace 60 alters with varying proximity of the drill 10 to workpiece 12 and hence such alteration of the trace can be used as a basis for providing a measure, which can be calibrated, of such proximity, which is a valuable basis for providing reliably repeatable drilling depth. The step of repeatability is achieved by providing a visually-assessable model or target size for the inner trace or display 60 as the latter diminishes in radius as drilling depth increases. In use, drilling is ceased when the target size is reached. An example of a conveniently-visible target size which can be provided is the diameter of drill bit 24. In other words, the inner trace 60 may be set to merge into the central drill bit at the chosen depth.

In the above disclosure of the invention it has been assumed that the user's intention is usually to achieve orthogonal drilling of a workpiece. However in the less-frequently-encountered situation where non-orthogonal drill attitude is required, the above disclosure can be readily adapted as follows. For any given non-orthogonal drill attitude, the elliptical format of the traces produced by the embodiment of Figure 3 can be utilised in a manner corresponding to that discussed above in the last-preceding embodiment, by matching the in-use-produced profiles of the displays or traces 34, 60 and with pre-recorded and visually displayed ellipsoid traces and data accordingly. For example, a visual display screen (not shown) may be provided for comparison purposes on the back of the drill's main body 18. Alternatively, or in addition, a template, for example a disposable printed transparent sheet-plastic template or translucent paper sheet template may be placed or mounted on the workpiece 12 and itself provided with printed comparison profiles corresponding to particular drilling angles frequently required. In a similar manner, it is likewise envisaged that in situations where accuracy is not crucial, then there may be provided simple reference profiles such as 'egg-shapes' likewise corresponding to required drilling angles.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the protection which is defined by the appended claims. For example, it is envisaged that the orthogonal direction with respect to the workpiece can be in any plane necessary/desired with respect to the workpiece so it is to be understood that the above description applies to 3-dimensional (azimuthal) geometry as well as to 2-dimensional geometry. Furthermore, the source of energy to power the laser can be any suitable means including for example batteries connected to the laser.

It will be understood from the foregoing that the embodiments of the invention provide a relatively simple and straightforward basis for establishing an orthogonal relationship between a hand-held drill or the like, and a flat or planar workpiece. It will also be understood that if the workpiece itself departs significantly from planarity in its surface profile in the region of the drilling point and outwards to the laser trace, such departure will affect the perceived form of the laser-generated trace produced by the drill, and hence the interpretation given by the user to such trace as evidence of, or not, orthogonality of the drill (or the like) with respect to the plane of the workpiece.

Assuming, therefore, planarity of the workpiece (such as a typical flat wooden plank or synthetic counterpart sheet material) accordingly, and assuming that an embodiment of the invention has been used to establish orthogonality between the drill and the workpiece, there will be the said orthogonal relationship between the drill and the workpiece in any chosen plane of measurement, subject of course merely to the relevant level of accuracy or tolerance applicable to a 'judged-by-eye' value of this kind. The orthogonal relationship 'in any chosen plane of measurement' arises because the method of the invention is not, in itself, inherently applicable to any particular 'plane of measurement', but, because the laser trace inherently extends (with interruptions or spaces) entirely around the drilling point, visually detectable variations-from-orthogonality will be perceptible regardless of the nominal plane in which the drill may be considered to lie at any particular instant of use.

Therefore, once orthogonality has been established, that angular relationship with the workpiece can be used as a basis, should it be desired, as a starting point for measured departures from orthogonality in any particular plane with respect to the workpiece desired by the user. In general terms, there may be used as an adjunct to the method of the invention, any applicable device or method for angular measurement, to enable such. An example of such angular measurement applied as an adjunct to the invention will now be discussed. Thus, for example, a mobile phone having a 'spirit level' function including a protractor-based angular-offset measurement capability could be employed, strapped or otherwise fastened to the drill, so as to provide a readily-accessible 'angular-offset-from- orthogonality' facility. Other instruments (than a mobile phone) having correspondingly-applicable 'measured tilt' function may be used instead. It will be appreciated that such 'measured offset from orthogonality' may be applied in any plane radiating from what may be considered as the 'central orthogonality axis' of the drill, whereby this function may be considered to be effective in any chosen plane of three-dimensional geometry with respect to the workpiece.

If desired, such 'measured-offset' functions, and indeed the more basic functions of the apparatus of the invention may, be monitored and for example recorded and plotted, as a basis for accurate repetition, by including known movement-sensing-and-recording apparatus, suitably attached to the drilling or boring or the like article-processing apparatus. The output of such apparatus could conveniently be displayed on a screen located on the back of the drill body. A facility to signal, for example audibly, when a pre-selected attitude is attained may be provided.

The above aspects of the invention are specifically disclosed in relation to corresponding claims thereto in the now-following text. Thus, according to these further aspects of the invention there is provided a method of controlling the attitude of hand-held article processing apparatus comprising, as elsewhere described and claimed herein, the steps of presenting said article processing apparatus to an article to be processed while hand-holding said article processing apparatus; causing rotary laser or-the-like visible beam generating means mounted on a chuck or related rotary tool-mounting of the apparatus, for rotation therewith about the axis of drilling, boring or the like of the apparatus, to produce a circular or distorted circular pattern or display on or in relation to the workpiece to be drilled, according to the attitude of same relative to the workpiece; and using said circular or distorted circular pattern or display to interpret the attitude to be adopted by said apparatus, and modifying or not the attitude of said hand-held article processing apparatus accordingly; characterised by providing in association with said circular or distorted circular pattern or display, proportion-indicating means, adapted to assist the visual assessment of said pattern or display by the user, whereby the user can more readily visually or mentally assess the proportion of said circular or distorted circular pattern or display which is visible to him/her during use, whereby, in consequence it can likewise be decided whether or not said circle is distorted and thus whether the article processing apparatus is orthogonal to its workpiece. And according to the aspects of the invention now disclosed, such method is characterised by providing the drill or the like hand-held article processing apparatus with angular- offset measurement or indication means, and said method comprising the step of employing said angular-offset measurement or indication means to determine or indicate a desired offset from a basis of orthogonality of said drill or the like apparatus, said basis of orthogonality being determined by visual assessment of said circular or distorted circular pattern or display, as aforesaid.

The method of these aspects of the invention is further characterised by the step of employing said angular-offset measurement or indication means to provide a signal operative to display a measure of said angular offset or to effect an input to computer means responsive to such signal.

The corresponding apparatus aspects of the invention include the provision of display means connected to the angular-offset measurement means to receive said signal and adapted to provide visual images facilitating manual control of the hand-held article processing means accordingly.

Another aspect of the invention relating to these 'measured offset starting from orthogonality' functions of the invention provides said drill or the like hand-held article processing apparatus additionally with proximity, position, or motion-sensing means, and the method comprises the step of employing said proximity, position, or motion-sensing means to determine or indicate a desired proximity or positional reference of said drill or the like apparatus from a basis of orthogonality with respect to a workpiece, said basis of orthogonality being determined by visual assessment of said circular or distorted circular pattern or display, as aforesaid. The proximity, position, or motion- sensing means, may provide a signal containing information enabling the display of a measure of said position or sensed motion or to effect an input to computer means responsive to such signal. The embodiment of the invention represented by the trace shown in Figure 4 includes additional crosshair element 56 and 58 which are produced by further lasers. The lines are produced by a lens such as a Powell lens and these laser lines may be of a different colour to the traces 34 and 60.

ANNEX TO THE DESCRIPTION

For powered hand drills, this invention offers several visual and digital methods for angles, depth & positional guidance. Operations with such drills are usually carried out by eye, without any form of guidance, but methods have been proposed; including lasers or light sources attached to the chuck, on the basis that rapid rotation of such appears to the human eye as a continuous shape. In particular, rotation of such a laser with the drill axis orthogonal to the workpiece in two planes will appear to an operator as a circle with the drill hole at its centre; and as an ellipse, the eccentricity of which is a function of drilling angle, if the drill is not orthogonal in at least one plane.

Such arrangements suffer from the disadvantage that the whole laser-generated shape is not visible to the drill operator, because the drill itself always blocks part of the view. Without a view of the whole, it is very difficult to locate accurately the centre of the visible shape, and even to assess exactly what the shape is. Centring or even construing, say, a circle from only a 'floating' length of arc is virtually impossible. This can sometimes be difficult even if the full 'arc' can be seen without any reference points, as in the problem of distinguishing a nearly-full moon from a full moon.

The current invention offers always-visible defining points for such above shapes so that they can be identified, calibrated and centred.

a) To understand that it is a circle, for example, a clear view of a defined, delineated or framed semicircle offers a very accurate indication. The operator, therefore, needs to see only half of any shape with a diameter, usually the lateral 3 o'clock - 9 o'clock, clearly marked.

b) To achieve full symmetry about the drill hole, the operator must also be able to locate, and line up with the centre of the drill bit, both a 12 o'clock or a 6 o'clock 'pointer', and at least a 3 o'clock - 9 o'clock diameter of the shape.

(The above markers apply when the operator is looking 'over' or 'under' the drill; if looking along a side, the relevant diameter is 12 o'clock - 6 o'clock; and the relevant pointer is towards 3 o'clock or 9 o'clock).

A) Orthogonal Drilling using Crosshairs

Various forms of crosshairs are proposed to frame such a 'semi-shape'.

A segmented magnetic collar 38 is attached near the chuck end of the drill body, with short nonmagnetic breaks occurring at 12, 3, 6 and 9 o'clock, or more, in relation to the drill's axis of symmetry. Mounted on the chuck is at least one electrical conductor able to interact with the magnetic field from 38. When the chuck rotates, a current is electromagnetically induced in any conductor, but only where it 'engages' with the magnetic collar -there is no current at the aforementioned breaks. Alternatively, blips, different colour laser images or other perturbations can be produced to mark these points, and more if required.

The said intermittent current powers a laser or set of lasers 32, attached to the chuck at a distance from the drill axis, and usually pointing parallel to said axis, so that, in turn, any laser duly flickers on and off during rotation. If the drill is held steady and rotation is fast enough, the human eye 'sees' the laser light on the workpiece surface 29 as a shape, with gaps 42 as in Figure 2.

In Figure 1, the drill is orthogonal to the workpiece so the image is seen as a circle 50, with breaks as above.

This invention, therefore, provides reference points in the form of virtual crosshairs (12 o'clock - drillbit centre - 6 o'clock; and 3 o'clock - drillbit centre - 9 o'clock) as in Figure 2. For the crosshairs to be useful, the operator needs to be able to see all of the lateral diameter (usually the 3 o'clock - 9 o'clock), which is almost always possible. And, crucially, they will know when they can't see all of it (and can then arrange to do so).

Thus half of the laser-generated image is visible, and relevant edges and axes are clearly defined. The drill hole is placed at the dead centre of the shape by manoeuvring the drill whilst sighting via the crosshairs. That shape can then also be manipulated by tilting the drill so that it corresponds to the required angle, as long as it is kept centred on the drill hole.

A circle is seen for orthogonal drilling, and ellipses of different eccentricity, as below, for all other angles between drill axis and workpiece surface.

Figure 3 demonstrates how the crosshairs can be further improved. Another laser (or set thereof) is mounted on the chuck, preferably 180 ^Q opposite to each of the above laser or lasers, for balance and synchronisation and, rather than necessarily shining parallel to the drill axis, their angle to this axis can be adjusted, so that, if, for instance, a laser toed-in or out at a small angle (or set at a different diameter from the axis), will provide another set of arcs and perturbations. As in Figure 3, these provide further reference points for the virtual crosshairs and further improve sighting accuracy.

Also provided is one or more extra reference points on the 12 o'clock - drillbit axis section (or any other 'pointer' as above), thereby greatly helping alignment in the relevant plane. Figure 4 indicates how the crosshairs can be further improved if linear blips (as in radar), rather than gaps, are created at the relevant points in the chuck rotation. Other forms of perturbation, such as different colours, are also possible. These are also triggered from the drill body.

Section E shows how such orthogonal positioning is also the possible starting point for a digital relationship between drill and workpiece; exact relative angles, depths and positions can then be defined, tracked and programmed if required.

B) Depth of Drilling.

The second laser (set), above, can also be calibrated as a depth gauge. Once the desired drilling depth is established, by, for instance, pushing the bit through a piece of card, the angle of the second laser (set) is adjusted so that it forms a recognisable and repeatable shape on the workpiece when the drill reaches that depth. This shape could be a point (the end of the cone shape created by this angled laser), or a larger circle (conic section) equal in circumference, say, to the drill bit. This methodology also applies to the ellipses seen when drilling at an angle, as below - the chosen depth marker could then, for example, again be a point, or an ellipse with one axis equal to the drill bit diameter. See also Section E(b) below.

C) Non-Orthogonal Drilling.

If an angle other than 90 ⁹ is required in either plane, the lasers will form the shape of an ellipse that can be centred on the drill hole using the crosshairs. As above, it is necessary to define from a half- shape the exact ellipse, with the drill hole at its centre, which, again, requires the diameters to be specified by crosshairs; otherwise off-centre shape placement, and therefore the wrong ellipse shape, may result. There are several ways to calibrate the ellipse eccentricity against drilling angle:

a) The length of one axis is known - the diameter at which the fixed laser (set) is attached to the chuck - so, for great accuracy, the length of the other axis can readily be calculated for a required angle, or read off a table provided, and the workpiece marked accordingly. The drill is then angled until the apex of the ellipse (denoted by a laser perturbation) coincides with this mark (direction will also generally need to have been defined, as below).

b) For common angles, templates can be provided to draw around, or for temporary fixing, on the workpiece. The drill is then centred with respect to the template and the perceived laser- generated ellipse, and angled until the ellipse coincides with the template outline.

c) For angle drilling where accuracy is not crucial, 'egg-shape recognition' from a chart (attached to the drill?) is often good enough.

Section E(a) below also describes a very accurate digital method. D) Azimuthal Drilling Direction.

This is relevant only when drilling at an angle other than 90° in at least one plane. A crosshair acting as a pointer can define the drilling direction if it is aligned with marks on the workpiece, or with other geometry.

E) Digital Placement, Depth and Angles.

From A) above, the orthogonal drill position in 2 planes can be established in relation to the workpiece. This, together with a starting position with, say, the end of the drill just touching the workpiece, forms an initial defined (xl, yl, zl) position in relation to the start of the drill hole (xO, yO, zO), and therefore also forms the crucial connection between drill and workpiece.

Suitable detectors can be set or reset at this point so that further relative movement between the two can be specified, tracked, programmed or recorded.

Suitable detectors can include: movement (accelerometer), angle (tilt), and position (infra-red vs a sensor bar or similar, as in games consoles).

These detectors, separately or in combination, could then specify, starting from the above 'zero/reset' position:

a) Precise drilling angle relative to workpiece surface, as in, for example, a mobile phone's 'spirit level'.

b) Axial (z axis) drilling movement (drilling depth).

c) Azimuthal drilling angle.

d) Translational (x, y axes) movement.

Values for each could be shown on a screen, possibly one placed on the (back of the) drill body, or possibly one wirelessly connected.

Any of the parameters could be pre-set with signals to indicate when a required value is met.

Further drillings could be programmed in if the workpiece is also suitably defined, so that the sensors can then continue to track the above drill-workpiece relationship.