Abstract:
Method and device for aligning a holder with respect to a carrier. The holder comprises at least one slot, whilst the carrier comprises a carrier plate and at least one bar. The bar is pivotally connected to the carrier plate with a first end, and to an element capable of sliding movement in said slot with an end remote from said first end. Once the holder has been positioned with respect to the carrier, the element is connected to the holder.

Description:
TECHNICAL FIELD 
     The invention relates to a method of positioning a holder with respect to a carrier. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     In such a method and device, which is known from U.S. Pat. No. 5,651,599, the holder comprises a light modulation panel and the carrier is an optical element which is to be aligned with respect to the light modulation panel. To this end, use is made of an adjusting mechanism which has a plurality of dowels and eccentric pins which are connected to the carrier. The holder has a plurality of slots through which the dowels and pins extend. The position of the holder with respect to the carrier is adjusted by means of the eccentric pin, whereafter the holder and the carrier are rigidly connected together by means of screws. 
     A drawback of such a method is that it requires a relatively large number of operations before a holder is aligned in six degrees of freedom with respect to a carrier. These six degrees of freedom comprise three translation directions extending transversely to each other and three directions of rotation situated transversely to each other. 
     It is an object of the invention to provide a method in which a holder can be positioned in a simple manner with respect to a carrier in at least one direction, and subsequently fixed. 
     In the method according to the invention, the object is achieved in that the holder has at least one slot, while the carrier is provided with a carrier plate and at least a bar, a first end of which is pivotally connected to the carrier plate and an end remote from the first end is pivotally connected to an element which is slidable in the slot, the element being connected to the holder after positioning the holder with respect to the carrier. 
     After connection of the holder with the carrier, the holder is fixed with respect to the carrier in a direction extending parallel to the bar. 
     An embodiment of the method according to the invention is characterized in that the carrier is provided with at least six bars situated in planes extending transversely to the carrier plate, while at least two bars extend away from each other in a first plane extending transversely to the carrier plate, at least two bars extend away from each other in a second plane extending transversely to the carrier plate, and at least two bars extend away from each other in a third plane situated parallel to the second plane and transversely to the first plane, the holder being fixed with respect to the carrier in six degrees of freedom after connection to the elements. 
     The bars situated in the first plane and extending transversely away from each other, extend away from each other in a direction situated parallel to the carrier plate. By connecting the holder with these bars, a displacement of the holder in this direction extending parallel to the carrier plate can be prevented. Similarly, a displacement of the holder with respect to the carrier can be prevented in a direction in the second and the third plane and parallel to the carrier plate by means of the four bars situated in the second and the third plane. The holder can be fixed with respect to the carrier in a direction extending transversely to the carrier plate by means of the six bars extending transversely to the carrier plate. Moreover, the holder can also be blocked against pivoting about axes extending parallel and transversely to the carrier plate by means of the six bars extending transversely to the carrier plate. During positioning of the holder with respect to the carrier, the elements connected to the bars can slide through the slots and the elements can pivot with respect to the bars and the carrier plate. The holder is thus positionable in six degrees of freedom with respect to the carrier. After subsequent connection of the elements with the holder, the displacement of the holder in each of these six degrees of freedom is suppressed effectively. 
     The invention also relates to a device by means of which a holder can be positioned in a simple way with respect to a carrier, and subsequently fixed. 
     In the device according to the invention, this object is achieved in that the holder has at least one slot, while the carrier is provided with a carrier plate and at least a bar, a first end of which is pivotally connected to the carrier plate and an end remote from the first end is pivotally connected to an element which is slidable in the slot, the element being connectable to the holder. 
     The bar prevents a displacement of the holder with respect to the carrier in a direction parallel to the bar. 
     These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective elevational view of a device according to the invention, 
     FIG. 2 shows a carrier of the device shown in FIG.  1 . 
     Corresponding components in the Figures are denoted by the same reference numerals. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows a device  1  according to the invention, comprising a prism  2  and three holders  3  which are positioned with respect to the prism  2 . Each holder  3  accommodates a light modulation panel  4 . The device  1  forms part of a projection system in which each light modulation panel  4  is illuminated by light of a different color and in which light beams coming from the different light modulation panels  4  are combined with each other by means of the prism  2 . To obtain a desired image of the light beam coming from the prism  2 , the light modulation panels  4  should be accurately positioned with respect to each other and notably with respect to the prism  2 . Such a positioning is obtained by means of the positioning device  5  according to the invention, which comprises a carrier  7  connected by means of screws  6  to the prism  2 , and the holder  3  co-operating with the carrier  7 . The holder  3  has six solts  8  extending along the circumference of the holder  3 . Two pairs of slots  8  extend on both sides of the light modulation panel  4  in a direction denoted by X in the system of co-ordinates. The two other slots  8  extend in the Y direction. 
     The carrier  7  will be further described with reference to FIG.  2 . The carrier  7  comprises a carrier plate  9  which is provided near its center with an aperture  10  to be positioned opposite the light modulation panel  4 . The carrier plate  9  is provided along its circumference with apertures  11  for fixation of the carrier plate  9  to the prism  2  by means of the screws  6 . The carrier plate  9  further comprises two M-shaped elements  12  which are situated in planes extending in the X and Z directions along the longitudinal sides of the carrier plate  9 . Each element  12  has two plate-shaped bridge parts  13  extending transversely to the carrier plate  9  in the Z direction and being connected on a side remote from the carrier plate  9  to a V-shaped element  15  via a blade hinge  14 . The V-shaped element  15  is connected to a plate-shaped bar  17  via a blade hinge  16  on a side remote from the blade hinge  14 . On a side remote from the blade hinge  16 , the bar  17  is connected to a bridge part  19  via a blade hinge  18 . The bridge parts  13 ,  19  are rigidly connected to the carrier plate  9 . Each bridge part  13  is connected to the carrier plate  9  via two bridges  20 . Between the bridges  20 , each bridge part  13  is provided with a supporting element  21 . The supporting element  21  extends as far as the side of the carrier plate  9  remote from the M-shaped element  12 . 
     The carrier plate  9  is further provided with a bridge part  22  extending transversely to the carrier plate  9 , from which bridge part antennas  23  extending away from each other extend. The antennas  23  are situated in a plane extending in the Y and Z directions. Each antenna  23  comprises a bar  25  connected to the bridge part  22  via a blade hinge  24  and an element  27  connected to the bar  25  via a blade hinge  26 . 
     Before elucidating the positioning of a light modulation panel  4  with respect to the prism  2 , the operation of each bar  17 ,  25  will be described first. 
     The bars  17 ,  25  jointly prevent the elements  15 ,  27  connected thereto from being displaced in the Z direction. 
     Each bar  17  prevents the element  15  connected thereto from being displaced in a direction extending parallel to the bar  17 . In the same way, each bar  25  prevents displacement of the element  27  connected thereto in a longitudinal direction extending parallel to the bar  25 . 
     In the case of a force exerted on the element  15  in the Y direction, the element  15  will pivot about the blade hinges  14 ,  16 . 
     Similarly, in the case of a force exerted on the element  27  in the X direction, the element  27  will pivot about the blade hinge  26 , while simultaneously the bar  25  pivots about the blade hinge  24 . 
     As already described above, the carrier plate  9  is connected to the prism  2  by means of screws  6  inserted through apertures  11 . To prevent the supporting elements  21  from being directly supported on the glass of the prism  2 , a supporting plate (not shown) may be provided between the prism  2  and the carrier plate  9 . Forces exerted on the prism  2  are evenly distributed on the prism  2  by the supporting plate. 
     After fixation of the carrier plate  9  to the prism  2 , a holder  3  accommodating a light modulation panel  4  is positioned opposite the carrier  7 . The four slots  8  extending in the X direction are positioned opposite the elements  15 , and the two slots  8  extending in the Y direction are positioned opposite the elements  27 . Subsequently, the holder  3  is displaced in the direction indicated by the Z direction, while the elements  15  and  27  will extend through the slots  8 . Subsequently, the holder  3  can be positioned with respect to the carrier  7 . To this end, use is made of an external manipulator (not shown). The holder  3  is displaced in six degrees of freedom by means of this external manipulator. These six degrees of freedom are the displacements already described in the X, Y and Z directions and further a rotation α about an axis extending parallel to the X direction, a rotation β about an axis extending parallel to the Y direction and a rotation γ about an axis extending parallel to the Z direction. During displacement of the holder  3  in one or more of these directions, the slots  8  are moved with respect to the associated elements  15 ,  27 . Forces in the Y direction and X direction are then exerted on these elements  15 ,  27 , as a result of which the bars  17 ,  25  connected thereto will pivot about the associated blade hinges. After the holder  3  has been brought to the desired position with respect to the prism  2 , the elements  15  and  27  are connected to the holder  3  by means of, for example, UV curing glue. The holder  3  is now no longer displaceable with respect to the prism  2 . A displacement in the Z direction is prevented by the bars  17  and  25 . Moreover, the six bars  17 ,  25  prevent a rotation α, a rotation β and a rotation γ. A displacement in the X direction is prevented by the bars  17 , while a displacement in the Y direction is prevented by the bars  25 . The bridge parts  13  connected to the elements  15  prevent the carrier plate  9  near the bridge part  19  from being displaced in the Z direction at a relatively large force exerted in the Z direction on the elements  15 . If the carrier plate  9  is relatively rigid, the bridge parts  13  may be dispensed with. 
     It is possible to manufacture the M-shaped element and the V-shaped element  23  by means of punching or laser cutting from a plate to be formed for the carrier plate  9 . Subsequently, the M-shaped elements  12  and the plate part  22  are bent with respect to the carrier plate  9  so as to obtain the carrier  7  shown in FIG.  2 . 
     It is of course also possible to use the adjusting mechanism  5  for other applications, where an accurate positioning of a holder  3  with respect to a carrier is to be obtained.