U.S. patent application number 09/879241 was filed with the patent office on 2002-01-03 for lens fixture.
Invention is credited to Verbiest, Rik.
Application Number | 20020001143 09/879241 |
Document ID | / |
Family ID | 3896559 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020001143 |
Kind Code |
A1 |
Verbiest, Rik |
January 3, 2002 |
Lens fixture
Abstract
Lens fixture for removably attaching a lens at an apparatus,
which consists at least of, on one hand, a seat at the lens or at
an adapter piece and, on the other hand, an attachment mechanism at
the apparatus, which mechanism at least is composed of a carrier
structure with an opening for providing the lens or adapter piece
therein, and an elastically working pressing system comprising one
or more substantially radially working pressing elements, which
pressing system can cooperate with said seat of the lens, the
adapter piece, respectively, and, in coupled condition of the lens
or the adapter piece, exerts a permanent axial pressure force onto
this latter, wherein the lens fixture comprises pressing elements
formed by spring wire.
Inventors: |
Verbiest, Rik; (Eeklo,
BE) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE
FOURTH FLOOR
ALEXANDRIA
VA
22314
|
Family ID: |
3896559 |
Appl. No.: |
09/879241 |
Filed: |
June 11, 2001 |
Current U.S.
Class: |
359/819 ;
359/811; 359/827 |
Current CPC
Class: |
G02B 7/14 20130101 |
Class at
Publication: |
359/819 ;
359/811; 359/827 |
International
Class: |
G02B 007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2000 |
BE |
2000/0375 |
Claims
1. Lens fixture for removably attaching a lens at an apparatus,
which consists at least of, on one hand, a seat at the lens or at
an adapter piece and, on the other hand, an attachment mechanism at
the apparatus, which mechanism at least is composed of a carrier
structure with an opening for providing the lens or adapter piece
therein, and an elastically working pressing system comprising one
or more substantially radially working pressing elements, which
pressing system can cooperate with said seat of the lens, the
adapter piece, respectively, and, in coupled condition of the lens
or the adapter piece, exerts a permanent axial pressure force onto
this latter, wherein the lens fixture comprises pressing elements
formed by spring wire.
2. Lens fixture according to claim 1, wherein said seat consists of
one or more recesses, which either or not extend along the entire
circumference of the lens or the adapter piece.
3. Lens fixture according to claim 1, wherein the seat shows a
contact surface for each respective pressing element which extends
at an angle in respect to a radial plane of the lens or the adapter
piece which is smaller than the friction angle which is determined
by the materials and the surface condition of, on one hand, the
aforementioned contact surface and, on the other hand, the pressing
element cooperating therewith.
4. Lens fixture according to claim 3, wherein the aforementioned
contact surface extends at an angle in respect to the vertical
which is smaller than 30.degree. and preferably is of the order of
magnitude of 15.degree..
5. Lens fixture according to claim 1, wherein several pressing
elements are provided along the circumference which preferably are
distributed along the circumference in a rotationally symmetrical
manner.
6. Lens fixture according to claim 1, wherein the whole is provided
with means which allow a snapping-on of the lens or the adapter
piece in the carrier structure against the force exerted by the
elastically working pressing system, whereby said means comprise at
least an inclined surface and/or a conical part at one extremity of
the lens or the adapter piece, such that, when providing the lens
or adapter piece in the aforementioned opening, the pressing system
is pushed open in order to finally snap on in said seat.
7. Lens fixture according to claim 1, further comprising
stop-forming parts, on one hand, at the lens or the adapter piece
and, on the other hand, at the apparatus, such that, by the
intermediary of the pressing system, the lens or the adapter piece
with the pertaining part is pressed axially against the apparatus
and/or the carrier structure.
8. Lens fixture according to claim 1, wherein each spring wire
concerned extends substantially tangential in respect to the lens
or adapter piece, the opening for the lens or adapter piece,
respectively.
9. Lens fixture according to claim 1, wherein the spring wire, at
least in active condition, is held substantially next to two
extremities and is bent out in the middle.
10. Lens fixture according to claim 1, wherein the aforementioned
attachment mechanism comprises a control mechanism with which the
pressing element, pressing elements, respectively, can be brought
into at least two positions, to wit an inactive position whereby
the lens or adapter piece can be removed from said opening, and an
active position whereby, when the lens or adapter piece is provided
in the attachment mechanism, the pressing element, pressing
elements, respectively, exert a force upon the lens.
11. Lens fixture according to claim 10, wherein this lens fixture
comprises two or more pressing elements and wherein the control
mechanism comprises a ring-shaped element extending around said
opening, as well as couplings between this ring-shaped element and
the pressing elements, such that these can be moved by means of
rotating them, and a control element for rotating the ring-shaped
element.
12. Lens fixture according to claim 11, wherein the spring wires,
at one extremity, are seated in a seat and, at the other extremity,
cooperate with slots provided in the ring-shaped element, whereby
these slots each extend in an inclined manner in respect to the
local tangential direction.
13. Lens fixture according to claim 10, wherein the control
mechanism comprises one or more overcentersystems which hold the
control mechanism in one or both of said positions.
14. Lens fixture according to claim 10, wherein the control
mechanism comprises elastic means which force the control mechanism
into a well-defined position, as well comprises a locking system
with which it can be locked, against the force of said elastic
means, in a position in which the pressing element, pressing
elements, respectively, are in one of the aforementioned positions,
either the inactive position or the active position.
15. Lens fixture according to claim 10, wherein the control
mechanism effects on the spring wire, the spring wires,
respectively, in such a manner that these are displaced in the
proximity of one extremity.
16. Lens, adapter piece for a lens, respectively, said lens or
adapter piece being provided with a seat allowing that it can be
attached in an apparatus, by means of a lens fixture according to
claim 1.
17. Apparatus, more particularly a projector, said apparatus being
provided with an attachment mechanism allowing for the fixation of
a lens or an adapter piece in this apparatus by means of a lens
fixture according to claim 1.
18. Lens fixture for removably attaching a lens at an apparatus,
which consists at least of, on one hand, a seat at the lens or at
an adapter piece and, on the other hand, an attachment mechanism at
the apparatus, which mechanism at least is composed of a carrier
structure with an opening for providing the lens or adapter piece
therein, and an elastically working pressing system comprising one
or more substantially radially working pressing elements, which
pressing system can cooperate with said seat of the lens, the
adapter piece, respectively, and, in coupled condition of the lens
or the adapter piece, exerts a permanent axial pressure force onto
this latter, wherein: the aforementioned attachment mechanism
comprises a control mechanism with which the pressing element,
pressing elements, respectively, can be brought into at least two
positions, to wit an inactive position whereby the lens can be
removed from said opening, and an active position whereby, when the
lens or adapter piece is provided in the attachment mechanism, the
pressing element, pressing elements, respectively, exert a force
upon the lens or upon the adapter piece; and the control mechanism
comprises elastic means which force the control mechanism into a
well-defined position, as well comprises a locking system with
which it can be locked, against the force of said elastic means, in
a position in which the pressing element, pressing elements,
respectively, are in one of the aforementioned positions, either
the inactive position or the active position.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a lens fixture, more particularly
a fixture for removably attaching a lens at an apparatus.
[0002] In the first place, the invention is intended for fixing a
lens in a projector; it is, however, clear that it can also be
applied in other devices.
[0003] Already, different kinds of lens attachment systems are
known. A first classical system consists of a screw thread
connection which, however, shows the disadvantage that it is
cumbersome to attach the lens, unscrew it, respectively. A second
classical system consists of a bayonet coupling, whereby the lens
has to be inserted axially into a seat and subsequently has to be
rotated over a well-defined angle. Such bayonet coupling, however,
does not offer a large rigidity, which, in the first place, forms a
disadvantage with large lenses, as these, due to the influence of
their weight, are no longer kept at their location in an efficient
manner.
[0004] Apart therefrom, other lens attachment systems are known,
whereby use is made of a so-called lens port, or of fins situated
around the lens. These systems show the disadvantage that they are
rather cumbersome in use.
[0005] From the patent documents U.S. Pat. Nos. 4,249,799,
4,062,030 and GB 1.590.752, fixtures are known, amongst others,
lens fixtures, with radially movable pressing elements, whereby in
coupled condition also a permanent axial pressing force is created.
The systems disclosed in these documents apply lever systems and
the like, which have the disadvantage that they take up a lot of
space. Moreover, they are provided with helicoidal springs, the
tension force of which mostly is rather limited.
SUMMARY OF THE INVENTION
[0006] The present invention aims at a lens fixture which allows to
attach a lens in an efficient manner very stable in an apparatus,
even in the case of large lenses, more particularly lenses with a
weight of several kilograms, whereby this lens can be attached in
the apparatus, as well as removed therefrom, in a smooth
manner.
[0007] To this aim, the invention relates to a lens fixture for
removably attaching a lens at an apparatus, which consists at least
of, on one hand, a seat at the lens or at an adapter piece and, on
the other hand, an attachment mechanism at the apparatus, which
mechanism at least is composed of a carrier structure with an
opening for providing the lens or adapter piece therein, and an
elastically working pressing system comprising one or more
substantially radially working pressing elements, which pressing
system can cooperate with said seat of the lens, the adapter piece,
respectively, and, in coupled condition of the lens or the adapter
piece, exerts a permanent axial pressure force onto this latter,
with the characteristic that the lens fixture comprises pressing
elements formed by spring wire.
[0008] By using one or more radially movable pressing elements, a
very efficient clamping attachment is obtained.
[0009] Due to the permanent axial pressing force, the important
advantage is created that the lens, once clamped, always remains in
the same position and no longer can shift in axial direction.
[0010] By applying spring wire for the pressing element, pressing
elements, respectively, in other words, applying hereto wire-shaped
elements which, for example, are made of spring steel, amongst
others, the advantages are obtained that said elements take up
little space and therefore easily can be mounted around the opening
in which the lens is provided, that they can be fixed in the
carrier structure in a simple manner, for example, by providing
them in a small seat, and that, notwithstanding their small
dimension, can provide rather a large tension.
[0011] Preferably, the spring wires are positioned substantially
tangential around the lens, or at least around the opening in which
the lens is provided. Hereby, each respective spring wire, at least
in active condition, substantially is held in the proximity of two
extremities and therefore can be bent out elastically in the
middle, according to a direction radial to the opening in which the
lens is provided.
[0012] Preferably, the seat at the lens consists of one or more
recesses. In the most preferred form of embodiment, this seat
extends along the entire circumference of the lens.
[0013] Practically, it is preferred that the seat shows a contact
surface which extends in an inclined manner in respect to the axial
direction of the lens. As a result of the effect of the radially
movable pressing element, the radially movable pressing elements,
respectively, onto each pertaining contact surface, in this way the
creation of a radial as well as an axial force component is
obtained in a constructively simple manner, as a result of which
the lens is enclosed laterally and held, as well as pressed-on
axially, preferably against stop parts especially provided to this
purpose.
[0014] According to a particular characteristic of the invention,
the aforementioned contact surface extends in respect to the
vertical at an angle which is smaller than the frictional angle
determined by the materials and the surface condition of, on one
hand, said contact surface and, on the other hand, the pressing
element cooperating therewith. In this manner, a self-braking
effect is created, as a result of which this lens, regardless of
the weight thereof, will not be loosened by itself.
[0015] In practice, the aforementioned angle will be smaller than
30.degree. and even better will be of the order of magnitude of
15.degree..
[0016] In a preferred form of embodiment, several pressing elements
are provided along the circumference, which, for example, are
distributed along the circumference in a rotationally symmetric
manner. In the most preferred form of embodiment, this will be
three or four in number. By using at least three pressing elements,
a well-balanced clamping will be guaranteed, whereas by using
preferably maximum four pressing elements, a constructively rather
simple mounting of these pressing elements in the carrier structure
can be provided for.
[0017] According to another preferred characteristic of the
invention, the unit has means which allow a snapping-on of the lens
in the carrier structure against the force exerted by the
elastically working pressing system. As a result of this, the lens
can be provided in the apparatus in a simple manner by sliding it
into the aforementioned opening of the carrier structure, whereby
it then automatically becomes attached.
[0018] Although it is not excluded to realize the lens fixture in
such a manner that the lens can be removed exclusively by means of
a tool or of another accessory, it is preferred that said
attachment mechanism comprises a control mechanism with which the
pressing element, the pressing elements, respectively, can be
brought into at least two positions, to wit an inactive position
whereby the lens can be removed from said opening, and an active
position whereby, in any case, if the lens is provided in the
attachment mechanism, the pressing element, the pressing elements,
respectively, hold the lens and, more particularly, exert a force
upon the lens. Due to the control mechanism, the lens can be
loosened from said carrier structure in a particularly simple
manner, such by operating the control mechanism in a suitable
manner and subsequently sliding the lens axially out of the carrier
structure.
[0019] In a practical form of embodiment, the control mechanism
then will comprise a movable element, provided with means for the
displacement thereof, whereby this movable element cooperates with
the movable pressing element, pressing elements, respectively, and
can move the pressing element, pressing elements, respectively,
radially outward, such that the lens can be freely removed from the
opening.
[0020] According to a particular aspect, which, according to the
present invention, is not limited to pressure elements consisting
of spring wires, but also can applied with lens fixtures having
pressing means realized in a different manner, the control
mechanism comprises elastic means which force the control mechanism
into a well-defined position, as well comprises a locking system
with which it can be locked, against the force of said elastic
means, in a position in which the pressing element, pressing
elements, respectively, are in one of the aforementioned positions,
either the inactive position or the active position. With a locking
in inactive position, the advantage is obtained that the control
mechanism can be permanently put into inactive position, as a
result of which the operator has both hands free for removing the
lens, which is particularly advantageous in case of heavy-weight
lenses of several kilograms. With a locking in active position, it
is obtained, amongst others, that a careless uncoupling is
prevented.
[0021] Other preferred characteristics are described in the
detailed description and the dependent claims.
[0022] In general, thanks to the invention described in the
aforegoing, the following advantageous features are obtained:
[0023] a perfect positioning of the lens against the apparatus,
without play;
[0024] a very rigid connection, suitable for heavy lenses;
[0025] a simple lens body, as the housing of the lens can be
manufactured exclusively by lathe work;
[0026] a lens fixture which allows that the lens is not bound to an
orientation, although, according to a variant, it is possible to
provide such orientation;
[0027] the insertion of the lens can be performed with two hands,
as no separate operations have to be performed;
[0028] the removal of the lens is very simple, as well;
[0029] the unit does not comprise any delicate or fragile parts and
can easily be made of wear and tear-resistant materials;
[0030] the fixture is self-centering.
[0031] It is noted that, according to the invention, said seat
either is provided at the housing of the lens itself, or at an
adapter piece in which a lens can be attached.
[0032] Evidently, the invention also relates to lenses and adapter
pieces equipped with special provisions, in particular with a seat
such as described in the aforegoing, which allow that such lens or
adapter piece can be attached in an apparatus by means of a lens
fixture as described in the aforegoing.
[0033] It is also evident that the invention also relates to
apparatuses provided with an attachment mechanism as described in
the aforegoing. According to the invention, by the term `apparatus`
a complete apparatus as well as a part of an apparatus as well as a
constructive part which can be attached at an apparatus, such as a
projector or such, has to be understood.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] With the intention of better showing the characteristics of
the invention, hereafter, as examples without any limitative
character, several preferred forms of embodiment are described,
with reference to the accompanying drawings, wherein:
[0035] FIG. 1 schematically represents a projector equipped with a
lens fixture according to the invention;
[0036] FIG. 2, in exploded view, represents a practical form of
embodiment of a lens fixture according to the invention;
[0037] FIGS. 3 and 4, in mounted condition, represent views
according to arrow F3 in FIG. 2, in an active and an inactive
condition, respectively;
[0038] FIG. 5 represents a cross-section according to line V-V in
FIG. 3;
[0039] FIG. 6, at a larger scale, represents a view of the part
indicated by F6 in FIG. 2;
[0040] FIG. 7, at a larger scale, represents a cross-section
according to line VII-VII in FIG. 3, at the moment when a lens 2 is
provided;
[0041] FIGS. 8 and 9 represent views analogous to that of FIG. 7,
however, for respectively two other positions;
[0042] FIG. 10 schematically represents the part indicated by F10
in FIG. 3;
[0043] FIG. 11 represents a view analogous to that of FIG. 2,
however, for another form of embodiment;
[0044] FIG. 12, in mounted condition, represents a view according
to arrow F12 in FIG. 11;
[0045] FIGS. 13 and 14, in perspective, represent two detailed
views of the parts indicated by arrows F13, F14, respectively, in
FIG. 12;
[0046] FIG. 15 represents the part of FIG. 14 in another
position;
[0047] FIG. 16 represents a view similar to that of FIG. 12,
however, for another position;
[0048] FIG. 17 represents another variant of the invention, whereby
an adapter piece is used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] As schematically represented in FIG. 1, the invention
relates to a lens fixture 1 for removably attaching a lens 2 in an
apparatus 3, more particularly, in a projector.
[0050] By means of FIGS. 2 to 10, hereafter a first preferred form
of embodiment is described.
[0051] As represented in these figures, the lens fixture 1
according to the invention at least consists of, on one hand, a
seat 4 at the lens 2 and, on the other hand, an attachment
mechanism 5 at the apparatus 3, which mechanism 5 is composed of at
least a carrier structure 6 with an opening 7 for providing the
lens 2 therein, and an elastically working pressing system 8
comprising at least one substantially radially movable pressing
element, however, in this example four of such pressing elements 9,
which, as further explained in the following, can cooperate with
said seat 4 of the lens 2 and, in coupled condition of the lens 2,
exert a permanent axial pressure force onto this latter, as
indicated by force Fa in FIG. 9.
[0052] As represented in the FIGS. 7 to 9, the seat 4 consists of a
recess provided in the housing 10 of the lens 2 which preferably
extends along the entire circumference. This seat 4 shows a contact
surface 11 extending in an inclined manner in respect to the axial
direction A of the lens 2, whereby this contact surface 11 extends
from the exterior of the recess towards the lowermost-situated
point of the recess in an inclined manner away from the apparatus
3.
[0053] The contact surface 11 extends at an angle B in respect to a
radial surface of the lens 2 which is smaller than the frictional
angle determed by the materials and the surface condition of, on
one hand, the aforementioned contact surface 11 and, on the other
hand, the pressing element 9 cooperating therewith. This angle B
preferably is smaller than 30.degree. and is of the order of
magnitude of 15.degree..
[0054] Further, a stop-forming part 12, in the shape of a
protruding rim, is formed at the lens 2, which rim can cooperate
with a stop-forming part 13 at the carrier structure 6 and/or the
apparatus 3.
[0055] The carrier structure 6 consists of a frame-shaped element
which preferably is composed of different parts, in this case a
base plate 14 and a cover plate 15, in which the necessary recesses
and seats are provided for taking up the different parts, such as
said pressing elements 9, therein.
[0056] In the schematic representation of FIG. 1, the carrier
structure 6 is mounted against the front side of the apparatus 3.
It is, however, evident that according to a variant, such carrier
structure 6 also can be mounted partially or entirely within the
housing of the apparatus 3.
[0057] The four pressing elements 9 are provided in a rotational
symmetric manner along the circumference of the opening 7. As
represented in FIGS. 2 to 10, they consist of spring wires 16
which, in mounted condition, substantially extend tangential in
respect to the opening 7 and the lens 2. At one extremity 17, the
spring wires 16 are provided with a bent part 18 with which they
are provided in an opening 19. In the carrier structure 6, also
seats 20 are provided which hold the spring wires 16 clamped fast
in the proximity of the starting part 21. In the represented
example, these seats 20 have, on one hand, a stop surface 22 and,
on the other hand, an opposed stop-forming part 23 which preferably
comes into local contact with the respective spring wire 16.
[0058] At their other extremity 24, the spring wires 16 also are
provided with a bent part 25. The bent parts 25 of the respective
spring wires 16 cooperate with a control mechanism 26, with which
the pressing elements 9, in this case, thus, the spring wires 16,
can be brought into at least two positions, to wit an active
position P1, whereby, as represented in FIGS. 3 and 9, the spring
wires 16 are situated in the path of the lens 2 and these spring
wires 16, in any case if the lens 2 is provided in the attachment
mechanism 5, exert a force upon the lens 2, and an inactive
position P2, such as represented in FIG. 4, whereby the lens 2 can
be removed from said opening 7.
[0059] Moreover, the control mechanism 26 comprises a movable
element, in the example a rotatable ring-shaped element 27, which
is seated in a seat 28 in the carrier structure 6, in this case
between the base plate 14 and the cover plate 15.
[0060] Further, this element 27 is provided with means for moving
it, more particularly, for rotating it, formed by a control
element, in this case, a handle 29, which is attainable during the
removal of the lens 2 and which possibly extends up to the exterior
side of the apparatus 3.
[0061] The ring-shaped element 27 and the bent parts 25 of the
spring wires 16 cooperate with each other by means of couplings 30
formed by, on one hand, slots 31 in the element 27 and, on the
other hand, the fact that, in mounted condition of the whole unit,
the bent parts 25 pass through these slots 31. The slots 31 are
extending such that the spring wires 16 are displaced substantially
radial at their extremities 24 when the element 27 is rotated. To
this aim, the slots 31 are directed in an inclined manner in
respect to the local tangential direction R1, more particularly
such as indicated in FIG. 6.
[0062] The control mechanism 26 also comprises two
overcentersystems 32-33 which hold the control mechanism 26 in the
set position, such that this latter can not automatically change
from one position into the other. As represented in the enlarged
view of FIG. 6, these overcentersystems 32-33 are formed by bent
and somewhat folded-back parts 34-35 at the end of each respective
slot 31, such that, viewed according to a circular path, protruding
parts 36 and 37 are formed in the respective rims of each slot
31.
[0063] Further, the whole also is provided with means which allow
that the lens 2 can be snapped on in the carrier structure 6
against the force exerted by the elastically working pressing
system 8. These means substantially consist in that at the
extremity of the lens 2, an inclined leading surface 38 or, in
other words, a conical part 39 is formed with such dimensions that,
when applying the lens 2 in the aforementioned opening 7, the
pressing system 8 automatically is pushed open until the spring
wires 16 snap on in said seat 4.
[0064] The functioning of the lens fixture 1 substantially is as
follows.
[0065] When applying the lens 2, the control mechanism 26 is put
into a position as represented in FIG. 3. Thereby, the lens 2 can
easily be attached in the opening 7 by sliding it axially into the
attachment mechanism 5 until it snaps on.
[0066] Hereby, successively the conditions are obtained which are
represented in FIGS. 7 to 9. At the beginning, the lens 2 will be
sitting with the conical part 39 between the spring wires 16. By
pressing the lens 2 further on, the spring wires 16 are pushed
radially outward by the conical part 39, as represented in FIGS. 7
and 8. By pressing on still further, the spring wires 16 become
seated in the seat 4, as represented in FIG. 9, whereby the
stop-forming parts 12 and 13, at the lens 2 and at the carrier
structure 6 or the apparatus 3, respectively, come into mutual
contact.
[0067] The position of the stop-forming means 12 and 13 and the
design of the seat 4, as well as of the spring wires 16, are chosen
such that the spring wires 16 in the conditions of FIGS. 7 to 9
will behave, more particularly will bend, successively such as
indicated by C1, C2 and C3 in the schematic representation of FIG.
10. Hereby, C1 shows a spring wire 16 in free condition. C2 shows
the condition whereby the spring wire 16 is bent in order to allow
an attachment of the lens 2, whereas C3 represents the condition of
FIG. 9, in other words, the condition of the spring wire 16 at the
moment that the lens 2 has been mounted.
[0068] As, in condition C3, the spring wires 16 still are bent out,
a permanent tension is created which, due to the inclined contact
surface 11, results in a considerable axial force component Fa, as
a consequence of which the lens 2 with the stop-forming part 12 is
permanently drawn against the stop-forming part 13.
[0069] As the spring wires 16, in mounted condition, are tensioned,
also a force component Fr of each bent part 25 on the rim of the
pertaining slot 31 will be created, such as in FIG. 6. Due to this
force component Fr and the protruding part 36 of the
overcentersystem 32, it is prevented that the ring-shaped element
27 revolves automatically.
[0070] As a result of the fact that the lens 2 can be snapped on in
a simple manner, this lens can be gripped with both hands, without
the necessity of performing other operations in the meantime.
[0071] In order to remove the lens 2, the control mechanism 26,
more particularly the ring-shaped element 27, must be turned, by
means of handle 29, from the position of FIG. 3 towards that of
FIG. 4. Thereby, the spring wires 16 are placed into a position C4,
as indicated in FIGS. 4, 9 and 10, as a result of which the lens 2
can be removed freely from in between the spring wires 16.
[0072] In FIGS. 11 to 16, a variant is represented.
[0073] In this variant, the spring wires 16 are not bent at their
extremities 24, but are each seated in a bent part 40 provided at
the ring-shaped element 27, as represented in FIG. 13.
[0074] Moreover, the control mechanism 26 is provided with elastic
means 41, in this case, a pressure spring, which force the control
mechanism 26 towards a well-defined position, in this case, said
active position. To this aim, the pressure spring exerts a force
onto a displacable element 42 which, by means of a protrusion 43,
engages at the circumference of the ring-shaped element 27, as a
result of which a force according to direction R2 is exerted
thereupon.
[0075] This control mechanism 26 also comprises a locking element
44 with which the whole can be locked in active condition. This
locking element is represented in FIGS. 12 and 14 in locked
position, and in FIGS. 15 and 16 in unlocked position, as well as
in a condition whereby the element 42 is pushed in against the
force of the pressure spring. In order to operate the locking
element 44, an operation button 45 is provided at the element 42,
with which button the element 42 can be pressed-in. This operation
button 45 is provided with a protrusion 46 which, in the highest
position of the element 42, can be brought behind a rim 47 or such
when being turned.
[0076] The functioning and the use of the device of FIGS. 11 to 16
substantially is similar to those described in respect to the first
form of embodiment. The only difference consists in that, in order
to remove the lens 2, the element 42 first has to be brought from
the condition of FIGS. 12 and 14 into that of FIGS. 15 and 16, by
turning the operation button 45 and pressing it. In pushed-in
condition, the lens 2 can be removed freely.
[0077] It is evident that according to a not-represented variant,
the elastic means 41 also can be realized such that they force the
control mechanism 26 towards the nonactive condition, whereas the
active condition explicitly has to be set by bringing the control
mechanism 26 in such condition and locking it.
[0078] As represented in FIG. 17, the seat 4 according to the
invention also can be provided at an adapter piece 48 in which a
lens 2 can be attached in one or another way.
[0079] The present invention is in no way limited to the forms of
embodiment described by way of example and represented in the
figures, however, such lens fixture can be realized in different
forms and dimensions without leaving the scope of the
invention.
[0080] So, for example, not necessarily all pressure elements 9
must be movable. Of two opposed pressing elements 9, for example,
one may consist of a rigid element, whereas the opposite is
elastically movable.
[0081] Preferably, the spring wires 16 directly cooperate with the
lens or the adapter piece, however, it is clear that according to
an alternative of the present invention, one or more of the spring
wires 16 can effect on rigid movable elements which then, by means
of the spring wires 16, are urged into the seat 4.
[0082] The carrier structure 6 may also be realized in one piece
with the apparatus 3.
[0083] Also, the ring-shaped element 27 does not necessarily have
to be a closed ring. The term "seat" has to be interpreted very
broad, and consequently said seat does not necessarily have to
consist of a recess. By such "seat", any surface is meant upon
which a force can be exerted.
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