Method and device for producing a plurality of microlenses

Abstract

Device and method for producing a plurality of microlenses from a lens material. The method includes: applying lens material intended for the embossing of the microlenses to a plurality of first lens molds distributed on a first embossing side of a first die for embossing of the microlenses, moving the first die and a second die located essentially parallel, in an X-Y plane, and opposite the first die, on top of one another in a Z-direction running essentially perpendicular to the X-Y plane, embossing the microlenses by shaping and curing the lens material, the shaping taking place by moving the first and second embossing sides on top of one another, up to a thickness D.sub.1 of the lens material in the Z-direction, wherein the lens material of each microlens at least during curing is separate from the lens material of each microlens which is adjacent in the X-Y plane.

Claims

1. A method for producing a plurality of microlenses from a lens material intended for the embossing of the microlenses, said method comprising: arranging a first embossing side of a first die to face upward, the first embossing side facing away from a receiving side of the first die, applying the lens material to a plurality of first lens molds distributed on the upwardly facing first embossing side of the first die, turning the first die by 180° such that the receiving side faces upward and the first embossing side faces a second die that is located opposite the first die and essentially parallel to the first die in an X-Y plane, moving the first die and/or the second die toward each other in a Z-direction that runs essentially perpendicular to the X-Y plane, said second die having a second embossing side, embossing the microlenses by shaping and curing of the lens material, the shaping taking place by moving the first and second embossing sides toward each other, measuring an embossing force during the embossing, and controlling the embossing according to the measured embossing force.

2. The method as claimed in claim 1, wherein the lens material of each microlens at least during curing is separate from the lens material of each microlens which is adjacent in the X-Y plane.

3. The method as claimed in claim 1, wherein during the curing and/or during the embossing an X-Y alignment of the first embossing side relative to the second embossing side takes place in the X-Y plane.

4. The method as claimed in claim 1, wherein the first die and the second die have alignment marks corresponding to one another for wedge fault compensation and/or for X-Y alignment.

5. The method as claimed in claim 1, wherein the lens material is applied by application of droplets.

6. The method as claimed in claim 1, wherein during curing free spaces at least partially surround the first lens molds for separation of the lens material of adjacent microlenses.

7. The method as claimed in claim 1, wherein said method further comprises compensating for shrinkage of the microlenses during curing.

8. A device for producing a plurality of microlenses from a lens material intended for embossing of the microlenses, said device comprising: a first die with first lens molds distributed on an embossing side of the first die, a first receiving apparatus for accommodating the first die on a receiving side of the first die that faces away from the embossing side, the first receiving apparatus comprising a robot arm configured to turn the first die by 180°, a second receiving apparatus for accommodating a second die on a receiving side of the second die which faces away from an embossing side of the second die, application means for application of the lens material to the first lens molds, embossing means for embossing of the microlenses by shaping and curing the lens material, the shaping taking place by movement of the first die and of the second die toward each other in a Z-direction, measurement means for measuring an embossing force during embossing, by means of which the embossing can be influenced, and control means by which the embossing means is controlled according to the measured embossing force.

9. The device as claimed in claim 8, wherein the lens material of each microlens can be applied by application means such that at least during curing it is separate from the lens material of each microlens which is adjacent in the X-Y plane.

10. The device as claimed in claim 8, wherein by X-Y alignment of the device during curing and/or during embossing an X-Y alignment of the embossing side of the first die relative to the embossing side of the second die can be carried out in one X-Y plane.

11. The device as claimed in claim 8, wherein first alignment marks of the first die are arranged corresponding to second alignment marks of the second die for wedge fault compensation and/or for X-Y alignment in the first die.

12. The device as claimed in claim 8, wherein the application means are made as droplet application means.

13. The device as claimed in claim 8, wherein the device has free spaces which at least partially surround the first lens molds for separation of the lens material of adjacent microlenses during curing.

14. The device as claimed in claim 8, wherein the device has compensation means for compensation of a shrinkage of the microlenses during curing.

15. A method as claimed in claim 1, wherein said lens material is a curable fluid.

16. A method as claimed in claim 15, wherein said curable fluid is a polymer in fluid form.

17. A method as claimed in claim 1, wherein said first die and said second die are moved in the Z-direction by position control.

18. A method as claimed in claim 1, wherein said embossing is controlled influenced at least during the curing of the lens material.

19. A method as claimed in claim 1, wherein the controlling of the embossing comprises controlling the embossing force.

20. A method as claimed in claim 4, wherein said alignment marks are located on the first and second embossing sides.

21. A method as claimed in claim 20, wherein said alignment marks are located on peripheral edges of the first and second embossing sides.

22. A method as claimed in claim 6, wherein said free spaces completely surround the first lens mold.

23. The device as claimed in claim 8, wherein said application means include a curable fluid.

24. The device as claimed in claim 23, wherein said curable fluid is a polymer in fluid form.

25. The device as claimed in claim 8, wherein said embossing means includes means for position control of the said first and second dies relative to each other.

26. The device as claimed in claim 8, wherein said control means is further configured to control said embossing means while said embossing means is curing said lens material.

27. The device as claimed in claim 8, wherein said control means is further configured to control said embossing force.

28. The device as claimed in claim 11, wherein said first alignment marks are located on the embossing side of the first die.

29. The device as claimed in claim 28, wherein said first alignment marks are located on at least one peripheral edge of the first die.

30. The device as claimed in claim 12, wherein said droplet application means is a droplet dispenser.

31. The device as claimed in claim 13, wherein said free spaces completely surround the first lens molds.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1a shows a schematic, cut side view of a device in a first inventive method step of application of a lens material for producing inventive microlenses of a microlens field,

(2) FIG. 1b shows a schematic of a method step of X-Y alignment by means of the position detection means,

(3) FIG. 1c shows a schematic of a method step of embossing by embossing means,

(4) FIG. 1d shows a schematic of a method step of curing by curing means and

(5) FIG. 1e shows a schematic of a microlens field which has been embossed and cured.

(6) In the figures advantages and features of the invention are labeled with the reference numbers which identify them according to embodiments of the invention, components or features with the same function or function with the same effect being labeled with identical reference numbers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

(7) FIGS. 1a to 1e show a method sequence according to one embodiment of the invention for producing a plurality of microlenses 10 (see FIG. 1e) from a lens material, specifically a curable fluid 2, in this case a polymer.

(8) FIG. 1a shows a first method step in which a first die 3 is accommodated in a first receiving apparatus (not shown) for accommodating the first die 3 on a receiving side 3a thereof. The receiving side 3a faces away from a first embossing side 3o of the first die 3, which is intended for embossing the microlenses 10. The movement of the receiving apparatus and thus also of the first die 3 is controlled by a control apparatus (not shown).

(9) In the first method step illustrated in FIG. 1a, the first embossing side 3o is arranged pointing upward, thereby enabling the curable fluid 2 to be applied on the first embossing side 3o by means of a droplet dispenser 1 by the weight of the curable fluid 2.

(10) The application takes place in the fluid, uncured form to a plurality of first lens molds 5 which are distributed on the first embossing side 3o. Embossing surfaces 5o of the first lens molds 5 in the illustrated exemplary embodiment are shaped concavely as negatives for the microlenses 10 which are to be produced. The curable fluid 2 is applied separately for each microlens 10 to be produced to the respective first lens mold 5 by means of a droplet dispenser 1. The latter is controlled by the control apparatus and applies an exactly defined amount of the curable fluid 2 to each of the first lens molds 5.

(11) In the subsequent method step which is shown in FIG. 1b, the first die 3 is turned by 180 degrees (flip) so that the receiving side 3a points up. This can take place for example by means of a robot arm which is used in particular also as a receiving apparatus. It is also conceivable that the die 3 is not turned and the die 4 approaches from the top.

(12) The first die 3 is located opposite a second embossing side 4o of a second die 4, which side points up, and is aligned by means of corresponding first alignment marks 6, 6′ of the first die 3 and second alignment marks 7, 7′ of the second die 4.

(13) The alignment marks 6, 6′, 7, 7′ are preferably located on one peripheral edge 3u, 4u of the first and second die 3, 4, preferably outside of a region covered by the lens molds 5.

(14) For this purpose there are detection means in the form of two microscopes 8, 9 and alignment means for alignment of the first die 3 relative to the second die 4. The alignment means are able to align the first die 3 and/or the second die 4 in one X-direction, one Y-direction and one rotation direction and their angular position to the horizontal plane (X-Y plane). The alignment of the angular position takes place by wedge fault compensation means which provide for a preferably ideally parallel alignment of the embossing sides 3o, 4o. The control of the wedge fault compensation means and of the X-Y alignment means takes place by the control apparatus which acquires from the detection means and optionally other sensor values about the relative and/or absolute position of the first die 3 and of the second die 4.

(15) The second die 4 is accommodated by a receiving apparatus (not shown). The first and the second receiving apparatus can be made especially as chucks with suction paths which fix the first and/or the second die 3 or 4. The first and/or second die 3, 4 can be made especially as wafers, the second die 4 in the illustrated exemplary embodiment having a planar embossing side 4o. The second embossing side 4o can also have second lens molds which are located at corresponding positions to the first lens molds 5 of the first die 3.

(16) Movement of the first die 3 and the second die 4 towards one another takes place in one Z-direction. During the movement towards one another especially continuously another X-Y alignment and/or wedge fault compensation takes place.

(17) The movement towards one another takes place up to a thickness D.sub.1 of the curable fluid 2, the detection of the thickness taking place preferably by measuring a distance d.sub.A between corresponding first and second alignment marks 6, 7 or 6′, 7′ or at other suitable sites on which the surfaces 4o, 3o of the dies are flat (see FIG. 1c).

(18) In the method step which is shown in FIG. 1d the curable fluid 2 is cured by curing means (here in the form of UV rays) which pass through the first die 3 and/or the second die 4. During curing, the force and the position re-adjustment of the two dies to one another are measured so that the force remains the same or at least increases.

(19) The curing can take place by any type of electromagnetic radiation, especially by UV light.

(20) A thermal curing or another other type of curing would also be conceivable. The type of curing depends mostly on the material used and is known to anyone skilled in the art in the field.

(21) In addition to the X-Y alignment and the wedge fault compensation at least shrinkage of the curable fluid 2 in the Z-direction, especially in addition shrinkage in the X- and Y-direction, is taken into account and a thickness D.sub.2 of the microlenses 10 is set so that the microlenses 10 have perfect optical properties and no dents or faults produced by shrinkage are produced.

(22) The thickness D.sub.1 and D.sub.2 corresponds especially to the maximum thickness of the lenses in the Z-direction.

(23) As soon as curing is completed, the first die 3 is detached from the second die 4 and microlenses 10 which have been separated from one another remain on the second die 4. A mechanical separation after curing can be omitted.

(24) The separation takes place especially by a distance A between the embossing surfaces 5o which is dimensioned such that, after embossing and curing of the curable fluid 2 in the step shown in FIG. 1e, there is a distance B between the embossed and cured microlenses 10.

(25) Thus, during the entire method sequence on the periphery of each microlens 10 and the curable fluid 2 provided for the microlenses 10 there is a free space 11 in which the curable fluid 2 can spread or shrink within certain limits. In this way, the region of the microlenses 10, which is decisive for the optics is not adversely affected by corresponding forming so that the microlens 10 after curing the curable fluid 2 at least in the middle region of the microlenses 10 which is decisive for the optics, has an optimum shape with an optical axis of each microlens 10, which axis is aligned perfectly in the Z-direction.

REFERENCE NUMBER LIST

(26) 1 droplet dispenser

(27) 2 curable fluid

(28) 3 first die

(29) 3a receiving side

(30) 3o first embossing side

(31) 3u peripheral edge

(32) 4 second die

(33) 4a receiving side

(34) 4o second embossing side

(35) 4u peripheral edge

(36) 5 first lens molds

(37) 5o embossing surface

(38) 6, 6′ first alignment marks

(39) 7, 7′ second alignment marks

(40) 8 microscope

(41) 9 microscope

(42) 10 microlenses

(43) 11 free spaces

(44) A distance

(45) B distance

(46) D.sub.1 (maximum) thickness

(47) D.sub.2 (maximum) thickness

(48) X X-direction

(49) Y Y-direction

(50) Z Z-direction