CA1161210A

CA1161210A - Adjustment washer device mounted as a base for an operating instrument

Info

Publication number: CA1161210A
Application number: CA000381610A
Authority: CA
Inventors: Ernst Zieglmaier
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-01
Filing date: 1981-07-13
Publication date: 1984-01-31
Also published as: EP0045887A3; JPS57141587A; DE3029300C2; EP0045887A2; DE3029300A1; EP0045887B1

Abstract

A B S T R A C T
There is provided a device for adjustably positioning an operating instrument relative to an axis extending through the instrument for fixing the radial orientation of the instrument relative to the axis. The device includes mounting means defining the axis and supporting the instrument for movement relative to the axis, along with an adjustment mechanism operatively interposed between the operating instrument and the mounting means. The adjustment mechanism comprises a first adjustment segment having the instruments supported thereon, a second adjustment segment supported relative to the mounting means, and wedge-shaped recess means formed between the first and second adjustment segments. The adjustment mechanism further includes spindle means adjustably engaged within the wedge-shaped recess means at a plurality of locations spaced apart circumferentially of the axis operable to be adjustably moved to effect the spreading apart of the first and second adjustment segments to effect tilting of the operating instrument relative to the axis. This permits adjustment of the radial orientation thereof relative to the axis. The first and second adjustment segments are formed together integrally in one piece with a common hub portion therebetween, thereby to form said adjustment mechanism to undergo deformation during adjustment of the operating instrument.

Description

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The present invention relates to a device for enabl~
ing adjustment of the radial orientation or tilted position of an operating instrument relative to an axis extending through the instrument. More specifically, the invention is related to a device wherein an adjustment washer mechan-ism is operable for the mounting and adjustment of an operat-lng instrument such as a polygonal mirror, polygonal prism, or similar devices of the type which may be used in optical-mechanical scanning instruments for electronic printing devices. Other instruments including optical instruments may be angularly adjusted with the adjustment washer mechanism of the invention and the invention may also be useful for support of tools such as grinding tools for high precision operations, for example the grinding of polygonal mirrors.
Operating instruments such as polygonal mirrors which are to be adjustably positioned by the`present invention generally rotate upon a driven, radially ~ixed axis which i5 precisely mounted by means of bearings, for example, air bearings, and which rotate at high rotational speeds. The polygonal mirror will be supported upon a shaft plate or dish representing khe end of the mounting shaft and such a shaft plate will usually require surface grinding to high precision so that the polygonal mirror will not wobble during its rotating operation. For high precision printing, the position o~ the plane of the polygonal mirror must be adjusted exactly within circular arcs on the order o~ fractions of seconds in order to avoid undesired displacement of the scanning point.

Howeverr it will be found that shaft plates which are accordingly ground with sufficient precision will b.e relatively expensive to provide.
In order to avoid the necessity for excessive pre-cision in this regard, it.is known from German.Offenlegungs-schrift 27 17 299 to introduce between the shaft end and the polygonal mirror a washer consisting of two partial washers or discs of which the partial washer attached to the shaft is equipped with three adjustment screws having parallel axes, the screws pressing u~on the underside of the partial washer serving for support of the polygonal. mirror, the partial washer being on the other hand pressed down upon the first partial washer by sprlng means. The second partial washer is sligh~ly tiltable in relation to a middle bolt. By utiliza-tion of an appropriately fine thread, the positions of the twopartlal washers may thus be adjusted relative to one another thereby to compensate for possible deviation rom parallelism.
The known construction is, however, not sufficiently exact since within the adjustment washer device alone there will

2~ occur some play and the screws will easily loosen. Fine ad-justment with known devices of this type is thus difficult to achieve.
For adjusting topometry instruments, it is also known from German Auslegeschrift 25 15 828 to brace the separately constructed partial washers of the adjustment washer mechanism relative to each other by means of three balls, two of the~

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balls being arranged in paths with wedge-shaped extensions and being moved forwardly by means of screw spindles. At the same time, the two partial washers are pressed against one. another by spring force and the screw spindles thus permit an adjustment of the angular position of the partial washers in relationship to one another. However, this is also accomplished ~ith insufficient precision since, here again, the separated partial washers will experience some play relative to one another despite the complicated con-struction and they do not have sufficient durability forvery fine angular adjustments. The structure is also not suited for.devices which must rotate at..high rotational speeds The present invention.is directed toward the task of providing an adjustment washer device which is simpler in construction and operation than prior art devices and which will exhibit high accuracy.
SUM~RY OF THE INVENTION
Briefly, the present invention may be described as a device for adjustably positioning an operating instrument, such as a polygonal mirror, relative to an axis extending therethrough for fixing the radial orientation of said instrument relative to said axis, including mounting means defining the axis and.supporting the instrument for movPment relative to the axis and an adjustment washer mechanism operatively interposed between the operating instrument and the mounting~

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means, said adjustment washer mechanism comprising a first adjustment washer segment having the instrument supported thereon, a second adjustment washer segment supported relative to the mounting means, wedge-shaped recesses formed between the first and the second adjustment washer segments and spindle means adjustably engaged within the wedge-shaped recess means at a plurality of locations spaced circum-fsrentially of the axis operable to be adjustably moved radially thereof to effect spreading apart of the first and the second adjustment washer segments to effect tilting of the operating instrument relative to the axis thereby to enable adjustment of the radial orientation of the instrument relative to ~he axis. The first and second adjustment washer segments are formed together integrally in one piece with a common hub portion therebetween thereby to enable the adjustment washer mechanism to undergo deformation during adjustment of the operating instrument.
Because the adjus~ment washer mechan~sm is constructed as a single unitary piece of two partial washers, the ZO mechanism is free of play and because of its elasticity it can be adjusted by the utilization of the spindle means which comprise threaded spindles extending radially into the adjustment washer mechanism. Thus, by operation of the device of the invention, the instrument or tool which is supported thereon which may, in particular, be a polygonal mirror will be aligned so that it will be accurately positioned relative to the axis to avoid wobble upon verification of its beam deflection.

The inherent resistance -to deformation in the adjustment washer may be selected in accordance wikh the choice of materials and the dimensioning of the device to provide a sufficient restoring force in order to assure a rigid support which is free of play upon spreading or expan-sion of the partial washers. Advantageously, a restoring force acting upon the spreading bodies, which force will arise at a spreading of the corresponding partial washer sectors beyond their resting position, may be in the order lO of magnitude such that self-locking of the spreading bodies will occur. The construction which is achieved by the present invention is easy to operate and compact and it may be mounted for best free rotation at high rotat1Onal speed.
The adjustment washer mechanism of the invention 15 is formed so that the screw spindles engage therein along axes which intersect with the axis of the operating instru-ment at equal angular distances between the two partial washers. As a result, there is assured a uniform ad~ust-ability on all sides.
In accordance with the state of the art, balls which run in grooves of decreasing depths are suited as spreading bodies. Hawever, because of the one-piece construction of the adjustment washer mechanism in the present invention, the milling of the grooves and the insertion o the balls may 25 possibly present constructional difficulties.

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In this regard, the adjustment washer mechanism is arranged so that the screw spindles may be screwed into radial threaded bores in the hub thereof with conical screw heads being provided as the spreading means which slide in half-conically shaped recesses on both sides of the screw spindles. The screw spindles will rotate about their own axis and thus may be pro~ided with engagement means for a turning tool.
In accordance with this measure of the invention, lO there is provided a wedge construction which may be easily formed and which will enable fine adjustment to be performed, for fine adjustments the adjusting dlsplacement of the screw spindles being rather small only. The arrangement of the invention makes possible an easier outward displacement 15 of the screw spindles and the creation of favorable frictional conditions since the spreadiny bodies must not turn them-selves relativa to their paths or direction of movement.
The partial washers and the hub extending there-between may be made of duraluminum and the heads of the screw 20 spindles as well as the conical spreading bodies may be made of brass. This will provide an expedient combination of materials and by provision of conical spreading bodies which are formed on their rear side with angular gradations, auxiliary means may be provided for a more specific adjustment 25 and for better reproducibility of a performed adjustment operation In accordance with an especially favorable structural feature of the invention, the upper partial washer may be relatively easily bendable whereas the lower partial washer may expediently be made with a stiffer structure. The part of the adjustment: washer mechanism upon wh.ich the instrument or tool is placed may be made in the shape of a flat cup having an edge front surface upon which the instrument or tool may be placed and, accordingly, at least the upper partial washer may be formed in a flat cup form, that is to say not overly stiff from the hub to the outer edge. The lower partial washer may also have a similar shape wher~by 10. the spring constant will be reduced further. Conversely, the upper partial washer support.ing the instrument or tool may also be constructed purely with a disc shape having constant thickness and the thickness must.then, however, be selected for achievement of the required spring force range and for a sufficient strength which will make posslble dlstribution of the forces expended by the spreading bodies.
The invention also provides expedient fastening elements at a shaft or shaft plate formed as part of the mounting means of the instrument and on the tool or instrument itself whereby required play in the bore of the hub of the adjustment washer mechanism will serve to make possible bending of the tubular body comprising the hub.
The various features of novelty which characterize the invention are pointed out with particularly in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had~

to the accompanying drawings and descriptive matter in which ~here are illustrated and described preferred embodiments of the invention.
DESCRIPTION OF THE DR~WINGS
In the drawings:
Figure 1 is an exploded perspective view of an adjustable mounting assembly for a polygonal mirror in accor-dance with the present invention;
Figure 2 is a sectiona~ view of the assembly shown 10. in Figure l; and Figures 3 and 4 are, respectively, sectional side views showing different embodiments of the device of the invention.
DETAILED DESCR P~ION OF THE PREFERRED EMBOD.IMENTS
Referring now to the drawings, and particularly to Figures 1 and 2. wherein there i~l shown an assembly in accordance with the present invention and wherein.similar parts axe identified with like re~erence numerals, a polygonal mirror 1 which is intended for use in a light spot scanning devlce in electronically controlled printing is mounted upon a best free rotating shaft 2 having at its upper end a shaft plate 3. For attachment of the poly-gonal mirror 1 at the shaft plate 3 there is provided a screw bolt 4 which is threaded to be screwed into a threaded bore hole 5 in the shaft 2 or arranged~

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to be otherwise connected therewith. A ring or shim washer 6 and a nut 7 are provided for this purpose.
The screw bolt 4 is surrounded by a screw sleeve 8 which terminates a~ a plate 9 which is adapted to be placed upon the shaft plate~3.
During the direct screwing together of t:he parts described thus far, there exists the danger that the poly-gonal mirror 1, which consists of a thick metal plate, could rest somewhat askew because.of small irregularities lO.in the contact surfaces between the parts of the mounting assembly. If this should occur, wobble of the mirror 1 would result which could lead to inaccuracies particularly with regard to light spots.reflected by the mirror surfaces which would then be of uneven height. Avoidance of such 15 wobble usually re~uires highly precise finishing of the mounting surfaces with the cleanest possible assembly.
This highly precise surface finishing and clean assembly become superfluous by utilization of the present invention which essentially comprises an adjustment washer 20 mechanism 13 which is inserted.between the shaft plate 3 and the polygonal mirror 1.
The adjustment washer mechanism 13 consists of an integrally formed unitary member including an upper partial washer seqment 14 and a lower partial washer segment 15 with a hub 16 extending therebetween. Of course, it should be understood that a precise vertical orientation of the operating axis o the assembly depicted in Figure 1 is not necessary and the reference to parts which are located upwardly or downwardly is intended to relate primarily to the drawing. The actual operating position of the device may deviate from a vertical orientation.
The upper partial washer 14 consists of a washer blade 17 adjacent the hub 16 and an outer ring-shaped washer 10 edge 18 having greater axial extension and greater torsional rigidityO In the same manner, the lower partial washer 15 consists of a washer blade 19 and a thicker annular washer edge 20 into which there is formed a small groove 21 for receiving the plate 9. Through the hub 16 of the adjustment 15 washer mechanism 13 there extends an axial bore 22, the diameter o~ which is larger than the diameter of the screw sleeve 8 to an extent such that a slight slanted or tilted position of the hub 16 will not be absolutely avoided by the screw sleeve 8.
A practical embodiment c,f the adjustment washer mechanism involves one formed of duraluminum which may have, for example, a total diameter on the order of magnitude of 73 mm, a diameter of the bore 22 of 24 mm, an outer diameter of the hub 16 of 32 mm, and an inner diameter of the disc 25 edges 18 and 20 of 57 mm. The total height of the adjust~ent washer mechanism 13 may be 28 mm, the height of the individual washer edges 18 and 20 and of the hub 16 may be 10 mm, and that of the interspace between the partial washers 14 and 15 may be 8 mm. With these dimensions, a suitable measured bending resist.ance is achieved which enables a spreading apart of the partial washers 14 and 15 in selected sector areas which is completely free of play whereby there will not appear any short term deviations even in the possible appearance of out of balance forces or centrifugal forces.
At the spreading of.the selected sector areas of the 10 partial washers 14 and 15, the entire adjustment washer mech-anism will generally speaking be somewhat expanded in the axial direction. It is.however also possible that sector areas situated opposite the spread-apart sec.tor areas will be pressed toge~her. A determination of which of these 15 phenomena occurs will depend upon.the selected spreading mechanism.
In the embodiment depicted, spreading is accomplished by three screw spindles 26 which, in relation to the common axis o the polygonal mirror 1, the shaft 2, and the adjust-20 ment washer mechanism 13, are arranged to extend radiall~-at uniform angular intervals of 120. Each screw spindle 26 is threaded into a throughgoing radial bore 27 in the hub 16 and it has a screw head 28 which extends recessed into a conical ring 29. Upon rotation of the screw spindle 26, the 25 underside of the screw head 28 will rub along the conical ring 29 and it will be pressed thereagainst when the screw spindle is------~-~------------ ----------------------------screwed radially inwardly to a greater distance into theinterspace between.the partial.washers 14 and 15. The conical rings 29 are guided in the interspace between the two partial washers 14 and 15 by half-conical recesses 30 .5 and 31 which are essentially of a frustoconical configura-tionl The recesses 30 and 31, respectively, are milled or cut into one of the surfaces of the partial washers 14 and 15 facing each other and the recesses 30 and 31 are situated in an area of the relatively stiff washer edges 18 and 20 in such a manner that the spread.ing components of the conical rings 29 which are situated apart from..each other by 120 will overlap one another. Thus, the position of the partial washers 14 and 15 which will be inclined in relation to one another may be adjusted in any desired direction.
l$ The screw hea.d 28 is formed with markings 32 and the conlcal ring 29 may be ~ormed with annular indicia 33.
Since the conical ring 29 does not rotate between the recesses 30 and 31, chan~es in the spreading action which ; may occur may be determined by reading the position of the markings 32 relative to the indicia 33. The markings 32 may for example comprise an engagement slot for a screwdriver or other tool used to rotate the spindle 26. However, for yreater precision, it is preferred to provide two holes 34 in the screw head 28 which may serve for engagement of a turning tool.

In order to perform an adjustment operation, a light spot reflected by the polygonal mirror 1 at a distance of, for example, 8 meters, is observed in different positions of the polygonal mirror. The polygonal mirror 1 is then adjusted with the use of the screw spindles 26 until such time as the height or vertical location of a reflected light spot ~rom the mirror no longer changes during vertical rotation of the mirror about its axis.
Thus, a cal~brating operation Q~ the mirror may be achieved. ~
Figures 3 and 4 show embodiments of an adjustment washer mechanism which differ from the structure depicted in Figures 1 and 2 with respect to the construction of the partial washers. In accordance with Figure 3, the upper partial washer 14 is unchanged from that shown in Figure 2, whereas the lower partial washex 15' is not constructed so as to be of a cupped shape, but ra~her so as to be solid up to the bore ~2. Thus, during adjustment, change in the form or deormation occurs primarily in the hub 16 and in the upper partial washer 14.
In accordance with Figure 4, an embod~ment is shown wherein the lower partial washer 15' is unchanged with rela-tion to the embodiment shown in Figure 3, but where the upper partial washer 14' i5 solid and constructed somewhat thinner.
This somewhat reduced thlckness- is necessary in order that the adjustment washer mechanism will not ultimately bec~me too bend-resistant or that, with larger corrections, the hub 16, which will then solely undergo deformation, will be over-burdened.
A further variation of the invention may involve utilization of rel~tively thin washer edges 13 and 20 and the utilization of more than three screw spindles 26.
The adjustment washer mechanism 13 may be screwed onto the shaft plate 3 by means of screws which may extend through screw holes 35.
10. With regard to the conical ri~gs 29, it should be noted that their conical slope is such that the forces pressing them together between the recesses 30 and 31 yield them self-locking against disadjusting forces. In the preferred embodiment represented, the slope over the entire length of 7 mm of thç conical ring is approximately 0.5 mm, which corresponds to approximately 2~. One turn o~ the screw spindle 26 will ef~ct, depending on the thread pitch thereof, a spreading action of about 0 036 mm, so that with co~responding gradations on the indicia of the adjustable mechanism, there may be produced reproducible adjustment operations with spreading distances of 1 micron.
In the embodiments represented wherein the polygonal mirror I is pressed down onto the adjustment washer mechanism 13, the elastic forces produced by the adjustment washer----------------------~-------------------------------mechanism itself are not as essential for the achievement of rigidity and, in any case, there may be utilized materials for the adjustment washers which are hardenable or non-hardenable metals and also plastic.
In view of the foregoing, it will be seen that the adjustment washer mechanism of the present invention is not only highly efficient, but also simple to construct and inexpensive to manufacture.
While specific embodiments of the invention have been shown and described in detail to illustrate the applica-tion of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

WHAT IS CLAIMED IS:

1. A device for adjustably positioning an operating instrument relative to an axis extending through said instrument for fixing the radial orientation of said in-strument relative to said axis, including mounting means defining said axis and supporting said instrument for move-ment relative to said axis and an adjustment mechanism operatively interposed between said operating instrument and said mounting means said adjustment mechanism comprising a first adjustment segment having said instrument supported thereon, a second adjustment segment supported relative to said mounting means, wedge-shaped recess means formed between said first and second adjustment segments and spindle means adjustably engaged within said wedge-shaped recess means at a plurality of locations spaced apart circumferentially of said axis operable to be adjustably moved to effect spreading apart of said first and second adjustment segments to effect tilting of said operating instrument relative to said axis thereby to enable adjustment of the radial orientation thereof relative to said axis, said first and second adjustment segments being formed together integrally in one piece with a common hub portion therebetween thereby to form said ad-justment mechanism to undergo deformation during adjustment of said operating instrument.

2. A device according to claim 1 wherein said first and second adjustment segments are formed as partial washer segments of said adjustment mechanism.

3. A device according to claim 1 wherein said spindle means comprise three threaded spindles threadedly engaged within said adjustment mechanism and extending radially thereof to intersect said axis, said threaded spindles being located at equal angular distances between said first and second adjustment segments.

4. A device according to claim 3 wherein said threaded spindles are screwed into radial threaded bore holes in said hub portion, said threaded spindles having conical screw heads which are arranged to slide in said recess means on both sides of the surfaces thereof, said recess means being formed with a half-conical configuration, said threaded spindles being rotatable about their own axis and adjustably movable in the radial direction of said device, said threaded spindles including on back surfaces thereof engagement points for engagement of a turning tool.

5. A device according to claim 4 further including conical spreading bodies interposed between said first and second adjustment segments and said threaded spindles, said conical spreading bodies being formed with graduated indicia means.

6. A device according to claim 1 wherein said first and second adjustment: segments are formed as partial washers of said adjustment mechanism, wherein said partial washers and said hub portion integrally formed therewith are made of duraluminum, wherein said spindle means comprise threaded screw spindles having heads formed of brass and wherein conical spreading bodies are provided between said screw spindles and said partial washers which are made of brass.

7. A device according to claim 1 wherein said first adjustment segment having said instrument supported thereon is formed with a cup-shaped configuration with an edge portion defining a flat surface upon which said instrument may be placed.

8. A device according to claim 1 wherein said mounting means include a shaft upon which said second adjustment segment may be mounted, said shaft having a shaft plate extending transversely relative to said axis and engaging a generally parallel surface of said instrument, said device being provided with screw holes whereby said instrument may be attached on said shaft plate, said hub portion having an axial bore the diameter of which is large enough to permit a fastening bolt to extend there-through with some play for attachment of said instrument upon said shaft.

9. A device according to claim 1 wherein said mounting means comprise a shaft including a shaft plate, said shaft plate extending transversely to said axis, said adjustment mechanism being formed with a generally annular configuration and being mounted between said shaft plate and a surface of said instrument extending generally parallel to said shaft plate transversely of said axis.