Method and device for producing a lens wafer

Abstract

A method and a device for producing a lens wafer which has a plurality of microlenses, as well as microlenses produced from the lens wafer.

Claims

1. A method for producing a lens wafer having a plurality of microlenses, said lens wafer comprised of a lens material and a wafer, said method comprised of the following steps: rigidly fixing a first receiver in a receiver holding device; fixing a receiving side of a die in said first receiver, said receiving side of said die facing away from a stamping side of said die, the stamping side of the die having a stamping structure, the stamping structure having lens molds, said die being located opposite to the wafer; fixing a receiving side of the wafer in a second receiver, said receiving side of said wafer facing away from a stamping side of said wafer, said stamping side of said wafer being available to accommodate the lens material thereon; applying said lens material onto said stamping side of the wafer; stamping the lens wafer, comprising the steps of: shaping the lens material, comprising the steps of: individually controlling a plurality of actuators by respectively moving the second receiver and the wafer toward the die in a Z-direction in which the actuators are aligned to respectively act to shape the lens material accommodated on the stamping side of the wafer and equalize a wedge fault existing between the stamping sides during the shaping of the lens material to achieve parallel alignment of the stamping sides, the Z-direction running perpendicular to an X-Y plane and corresponding to a direction in which the wafer is to be stamped; during the individually controlling, adjusting an orientation of the second receiver relative to the first receiver for X-Y alignment of the wafer to the die in accordance with corresponding alignment marks in said die and said wafer, the adjusting comprising individually moving the second receiver in an X-direction using an X-drive and a Y-direction using a Y-drive to perform the X-Y alignment; and during the individually controlling and the adjusting, detecting with microscopes a relative position of the corresponding alignment marks of said die and said wafer to execute said X-Y alignment of said wafer to said die; and curing the shaped lens material, wherein the corresponding alignment marks are arranged at the same time in a depth of field region of the microscopes during the adjusting of the orientation.

2. The method as claimed in claim 1, wherein the individually controlling and/or the adjusting takes place continuously after a distance between the stamping sides is less than a predetermined distance D.

3. The method as claimed in claim 1 or 2, wherein the shaping takes place position-controlled.

4. The method as claimed in claim 1 or 2, wherein the corresponding alignment marks are provided on at least one peripheral edge of the stamping side of the die, and on at least one peripheral edge on the stamping side of the wafer.

5. The method as claimed in claim 1 or 2, wherein the individually controlling and/or the adjusting take place when both of the stamping sides are at least partially covered by the lens material.

6. The method as claimed in claim 1 or 2, wherein both the stamping side of the die and the stamping side of the wafer are located in the depth of field region of the microscopes during the individually controlling and/or the adjusting, and wherein the microscopes are fixed relative to the wafer.

7. The method as claimed in claim 6, wherein a distance D between the stamping sides in the Z direction is greater than 0 and smaller than the depth of field region of the microscopes in the Z-direction.

8. The method as claimed in claim 1, wherein the lens material is a polymer.

9. A method for producing a lens wafer having a plurality of microlenses, said lens wafer comprised of a lens material and a wafer, said method comprised of the following steps: rigidly fixing a first receiver in a receiver holding device: fixing a receiving side of said wafer in said first receiver, said receiving side of said wafer facing away from a stamping side of a die, the stamping side of the die having a stamping structure, the stamping structure having lens molds, said die being located opposite to the wafer, a stamping side of said wafer being available to accommodate the lens material thereon; fixing a receiving side of the die in a second receiver, said receiving side of said die facing away from said stamping side of said die; applying said lens material onto said stamping side of the wafer; stamping the lens wafer, comprising the steps of: shaping the lens material, comprising the steps of: individually controlling a plurality of actuators by respectively moving the second receiver and the die toward the wafer in a Z-direction in which the actuators are aligned to respectively act to shape the lens material accommodated on the stamping side of the wafer and equalize a wedge fault existing between the stamping sides during the shaping of the lens material to achieve parallel alignment of the stamping sides, the Z-direction running perpendicular to an X-Y plane and corresponding to a direction in which the wafer is to be stamped; during the individually controlling, adjusting an orientation of the second receiver relative to the first receiver for X-Y alignment of the wafer to the die in accordance with corresponding alignment marks in said die and said wafer, the adjusting comprising individually moving the second receiver in an X-direction using an X-drive and a Y-direction using a Y-drive to perform the X-Y alignment; and during the individually controlling and the adjusting, detecting with microscopes a relative position of the corresponding alignment marks of said die and said wafer to execute said X-Y alignment of said wafer to said die; and curing the shaped lens material, wherein the corresponding alignment marks are arranged at the same time in a depth of field region of the microscopes during the adjusting of the orientation.

10. The method as claimed in claim 1, wherein the microscopes are fixed relative to the die.

11. The method as claimed in claim 1, wherein the detecting takes place through the lens material.

12. The method as claimed in claim 1, wherein the X-drive and the Y-drive are separately stacked on the actuators.

13. The method as claimed in claim 12, wherein the Y-drive is stacked between the X-drive and a rotation means, the rotation means being configured to rotate the wafer around an axis of rotation which runs in the Z-direction.

14. The method as claimed in claim 12, wherein the X-drive and the Y-drive are separately stacked between the actuators and the wafer.

15. The method as claimed in claim 12, wherein the X-drive is stacked between the Y-drive and the actuators.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic cutaway side view of a device as claimed in the invention for producing a lens wafer which has a plurality of microlenses,

(2) FIGS. 2a to 2c schematically illustrate a method for producing a lens wafer according to one embodiment of the present invention,

(3) FIGS. 3a to 3c schematically illustrate a method for producing a lens wafer according to a second embodiment of the present invention, and

(4) FIGS. 4a to 4c schematically illustrate a method for producing a lens wafer, wherein a method according to FIGS. 2a to 2c, a modified die is used.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

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

(6) FIG. 1 shows a device according to the present invention for producing a lens matrix 25 which has a plurality of microlenses 24 (see FIGS. 2c, 3c and 4c).

(7) In the embodiments shown, the lens matrix 25 is stamped onto an especially planar wafer 2. A die 1 with one stamping side 1o with a stamping structure 21 which has lens molds 8 is held in a first receiving means. The first receiving means is comprised of a holding device 9 which is ring-shaped on the interior thereof. The holding device 9 includes a peripheral shoulder 9u which extends toward the interior of the ring-shaped holding device. A receiver 11, which is provided with suction paths 10, is inserted and fixed in said holding device 9 on said peripheral shoulder 9. In turn, the die 1 has a receiving side 1a facing away from the stamping side 1o. Die 1 is fixed on the receiving side 1a on the receiver 11 via the suction paths 10. In addition, the die 1 is supported along its peripheral edge 1u by an inner ring wall 9i of the holding device 9.

(8) The first receiving means is rigidly located in the device, on a rack which is not shown. Above the receiving means, optical position detection means are provided in the form of microscopes 22, 23 which are fixed or can be fixed relative to the receiving means or the die 1 at least in one Z-direction, which corresponds to one stamping direction. The Z-direction or stamping direction is orthogonal to an X-Y plane or to an X-direction and Y-direction which spans the X-Y plane. Exactly orthogonally to the Z-direction, and thus parallel to the stamping side 1o of the die 1, therefore to the X-Y plane, is a wafer 2 with its stamping side 2o opposite the stamping side 1o, at the instant of stamping of the lens matrix 25 onto the wafer 2. The lens matrix 25 and the wafer 2 jointly form a lens wafer 12.

(9) The wafer 2 can be fixed on, i.e., attached to, a movable second receiving means. The movable receiving means is comprised of actuators 19 which are aligned to act in the Z-direction. Actuators 19 can be, for example, spindles. The actuators 19 can be each individually controlled by one control means. There are one X-drive 18 and one Y-drive 17 on the actuators 19. With the X-drive 18 a movement of the wafer 2 in the X-direction which is controlled by the control means is possible, while the Y-drive 17 can cause a movement of the wafer 2 in the Y-direction.

(10) Furthermore, there is a rotation means 16 disposed between the actuators 19 and the wafer 2 with which a rotational movement, which rotates around an axis of rotation which runs in the Z-direction, can be executed by the control means.

(11) Between the X-drive 18, the Y-drive 17 and the rotation means 16 and the wafer 2 a receiver 14 is fixed which in turn has suction paths 13. On the suction paths 13 the wafer 2 can be fixed on its receiving side 2a which is opposite the stamping side 2o.

(12) The die 1 in the region of the peripheral edge 1u has outer alignment marks 4 which can be aligned with reference to outer corresponding alignment marks 6 of the wafer 2. The outer alignment marks 4, 6 are located especially laterally outside the area of the stamping structures 21 or the lens molds 8, preferably at no instant of the stamping process, especially of shaping, covered by a lens material which forms the lens matrix 25 in the form of a curable fluid 3. The outer alignment marks 4, 6 can be used for example for rough alignment of the die 1 relative to the wafer 2.

(13) Furthermore, the die 1 has inner alignment marks 5 which can be aligned to corresponding inner alignment marks 7 of the wafer 2. The inner alignment marks 5, 7 are located outside or between the lens molds 8, especially translationally symmetrically on the die 1 or the wafer 2. During the stamping process or during shaping, the alignment marks 5, 7 are covered with the lens material or the curable fluid 3 at least towards the end of the stamping process or shaping.

(14) The device has application means for applying the curable fluid 3, especially a polymer, in fluid form to the stamping side 1o and/or the stamping side 2o which are not shown. The application means can consist, for example, of a metering line which can be placed in the intermediate space between the die 1 and the wafer 2.

(15) The individually controllable actuators 19 can execute wedge fault equalization by the relative position of the alignment marks 4, 5, 6, 7 to one another being detectable by the position detection means 22, 23 and by a possible wedge fault being corrected accordingly.

(16) Likewise X-Y alignment takes place by the X-drive 18 and the Y-drive 17 as well as the rotation means 16.

(17) The die 1 and the wafer 2 are moved together by the actuators 19 which can be moved in the Z-direction and the curable fluid is shaped during the movement together.

(18) The stamping means furthermore comprise, in addition to the features provided for shaping, curing means for curing of the curable fluid 3 which are triggered by the control means as soon as the shaping of the lens wafer 12 is completed.

(19) The position detection means 22, 23 are located on the side of the receiver 11 facing away from the stamping side 1o, and the position is detected through the receiver and die 1 which are transparent to electromagnetic radiation, especially visible or UV light. As claimed in the invention it is especially advantageous if position detection means with a depth of field less than 100 m, especially less than 50 m, preferably less than 25 m, can be used.

(20) The wafer 2 is generally transparent to corresponding electromagnetic radiation. The wafer 2 can be non-transparent when the final product is not transmission lenses, but only reflection lenses.

(21) In the method step shown in FIG. 2a, curable fluid 3 is centrally applied to the wafer 2 by the above described application means (not shown).

(22) Subsequently, according to FIG. 2b and by means of the actuators 19, the wafer 2 is moved onto the rigid die 1 and during the movement together the curable fluid 3 is shaped by the curable fluid 3 moving from the center of the wafer 2 in the direction of, i.e., toward, the peripheral edge 1u or peripheral edge 2u.

(23) As soon as shaping according to FIG. 2c is completed, the movement in the Z-direction is stopped by the control means. The control quantity is, for example, a distance D between the stamping side 1o and the stamping side 2o.

(24) Until the preset distance D is reached and within the depth of field region of the position detection means, during the movement together, i.e., during shaping of the curable fluid 3, wedge fault equalization can take place continually by the wedge fault equalization means and/or an X-Y alignment can take place by the X-Y alignment means so that when the preset distance D is reached the die 1 is aligned exactly, and without wedge faults, relative to the wafer 2. The corresponding alignment marks 4, 5, 6, and 7 at this instant all have exactly the same distance and since the alignment marks 4, 5, 6, 7 are each arranged flush on the stamping side 1o or 2o, the distance of the alignment marks 4, 5, 6, 7 corresponds to the preset distance D.

(25) According to one preferred version, alignment takes place only within the depth of field, preferably during or after reaching the preset distance D.

(26) The wedge fault equalization and the X-Y alignment take place preferably while the distance D is less than 100 m, more preferably, less than 50 m, and most preferably less than 25 m.

(27) In the embodiment of the method according to FIGS. 3a to 3c the device according to FIG. 1 is more or less reversed so that the wafer 2 is located above the die 1. In this embodiment, the die 1 is moved onto the wafer 2, while the wafer 2 remains rigid.

(28) The position detection means are located underneath the die 1 in this case. The curable fluid 3 is applied into/onto the lens molds 8 by droplet deposition. In the case of concave lens molds 8, the curable fluid 3 is automatically held in a stable position by the force of gravity and the recess. In a convex lens mold the curable fluid has a relatively high viscosity in order to stabilize the polymer on the die or on the lens mold 8.

(29) By moving the die 1 and the wafer 2 closer to one another the curable fluid 3 will come into contact with the stamping side 2o of the wafer 2. Depending on the amount of curable fluid 3, the distance of the lens molds 8 to one another and the ambient conditions, the inner alignment marks 5, 7 can be separated by the curable fluid 3, air and a gas, especially inert gas, preferably nitrogen or vacuum.

(30) According to one version of the embodiment according to FIGS. 3a to 3c the die 1 is located above and the wafer 2 below, and the curable fluid 3 in this case can also be applied to the die 1 since as a result of the adhesion forces between the curable fluid 3 and the die the curable fluid 3 can adhere to the die 1.

(31) According to another embodiment of the invention shown in FIGS. 4a to 4c, in contrast to the embodiment according to FIGS. 2a to 2c, the die 1 has projections 26. The projections 26 extend above the stamping side to and in the projections 26 there are alignment marks 4, 5 so that the alignment marks 4, 5 can be located nearer the corresponding alignment marks 6, 7 when the lens wafer 12 is being molded. The result is even more accurate alignment at a given thickness or height of the microlenses 24.

(32) Otherwise the method according to FIGS. 4a to 4c corresponds to the method according to FIGS. 2a to 2c.

(33) The curable fluid 3 is cured by irradiation means for producing electromagnetic radiation, especially in the form of at least one lamp 27, preferably a UV lamp, which means are located above or within the receiver 11.