Light pipe array lens, optical finger navigation device with the lens and method for making the device
View Patent ↗An optical finger navigation device and method for making the device uses a light pipe array lens, which includes an array of light pipes formed in a monolithic block of material. The light pipe array lens is configured to function similarly to a fiber bundle lens to transmit light through the lens using the light pipes in the monolithic block of material.
1. A light pipe array lens comprising:
a monolithic block having first and second surfaces, the monolithic block being made of a first material, the monolithic block including a plurality of parallel cuts within the monolithic block that extend from the first surface of the monolithic block to the second surface of the monolithic block; and
a two-dimensional array of light pipes disposed in the monolithic block such that the light pipes extend from the first surface to the second surface, the light pipes being made of the same first material as the monolithic block, each of the light pipes being enclosed by walls made of a second material having an index of refraction lower than an index of refraction of the first material, wherein the walls are disposed in the plurality of the parallel cuts of the monolithic block and wherein the walls are formed in the parallel cuts of the monolithic block with the second material to define the light pipes that are enclosed by the walls.
2. The light pipe array lens of claim 1 , wherein the first material includes polymer with nanoparticles.
3. The light pipe array lens of claim 1 , wherein the second material includes optical epoxy.
4. The light pipe array lens of claim 1 , wherein the light pipes are disposed at an angle of approximately forty-five degrees from the bottom surface of the monolithic block.
5. An optical finger navigation device comprising:
a light source configured to emit light;
a light pipe array lens positioned to receive the light reflected from a navigation surface, the light pipe array lens comprising:
a monolithic block having first and second surfaces, the monolithic block being made of a first material, the monolithic block including a plurality of parallel cuts within the monolithic block that extend from the first surface of the monolithic block to the second surface of the monolithic block; and
a two-dimensional array of light pipes disposed in the monolithic block such that the light pipes extend from the first surface to the second surface, the light pipes being made of the same first material as the monolithic block, each of the light pipes being enclosed by walls made of a second material having an index of refraction lower than an index of refraction of the first material, wherein the walls are disposed in the plurality of the parallel cuts of the monolithic block and wherein the walls are formed in the parallel cuts of the monolithic block with the second material to define the light pipes that are enclosed by the walls; and
an image sensor array positioned to receive the light from the light pipe array lens to capture image frames of the navigation surface, the image frames providing displacement information of the navigation surface relative to the optical navigation system.
6. The optical finger navigation device of claim 5 , wherein the first material includes polymer with nanoparticles.
7. The optical finger navigation device of claim 5 , wherein the second material includes optical epoxy.
8. The optical finger navigation device of claim 5 , wherein the light pipes of the light pipe array lens are disposed at an angle of approximately forty-five degrees from the bottom surface of the monolithic block.
9. The optical finger navigation device of claim 5 , wherein the image sensor array is part of a navigation sensor, the navigation sensor including a navigation engine configured to estimate relative displacement of the navigation surface using the image frames of the navigation surface from the image sensor array.
10. The optical finger navigation device of claim 9 , further comprising a printed circuit board, the light source and the navigation sensor being mounted on the printed circuit board.
11. A method of making an optical finger navigation device, the method comprising:
fabricating a light pipe array lens that includes an array of light pipes in a monolithic block of material having first and second surfaces, the monolithic block including at least one of a plurality of microchannels that extend from the first surface to the second surface and a plurality of parallel cuts that extend from the first surface to the second surface, the light pipes being made of a first material, each of the light pipes being enclosed by walls made of a second material having an index of refraction lower than an index of refraction of the first material, wherein at least some of the light pipes and the walls are disposed in one of the plurality of microchannels and the plurality of the parallel cuts;
attaching the light pipe array lens to a navigation sensor having an image sensor array;
mounting the navigation sensor with the light pipe array lens onto a substrate; and
mounting a light source onto the substrate.
12. The method of claim 11 , wherein the monolithic block of the light pipe array lens is made of the second material.
13. The method of claim 12 , wherein the fabricating the light pipe array lens includes forming the microchannels in the monolithic block and filling the microchannels with the first material.
14. The method of claim 11 , wherein the fabricating the light pipe array includes forming the walls in the monolithic block such that each of the light pipes is defined and enclosed by the walls.
15. The method of claim 14 , wherein the forming the walls includes making vertical and horizontal cuts in the monolithic block and filling vertical and horizontal spaces formed by the vertical and horizontal cuts with the second material.
16. The method of claim 11 , wherein the fabricating the light pipe array lens includes forming the light pipes in the monolithic block at an angle of approximately forty-five degrees from the bottom surface of the monolithic block.
17. The light pipe array lens of claim 1 , wherein the walls of the monolithic block includes first parallel walls along a first direction and second parallel walls along a second direction that is orthogonal to the first direction.
18. The optical finger navigation device of claim 5 , wherein the walls of the monolithic block includes first parallel walls along a first direction and second parallel walls along a second direction that is orthogonal to the first direction.