Liquid multi-touch sensor and display device
High-resolution multi-touch sensor and display device where the interaction medium is liquid, enabling more realistic tactile experience for simulations of synthetic wet environments. Based on frustrated total internal reflection, the device employs liquid within a tank as the optical waveguide that receives light, such as infrared light, that undergoes total internal reflection and an imaging camera that detects light that escapes from the tank caused by frustration of the total internal reflection due to contact of the water by a user.
1. A liquid multi-touch sensor system, comprising:
a tank comprising side walls and a bottom wall, the tank being configured to contain a liquid therein and having an open front that exposes the liquid contained in the tank to a user of the liquid multi-touch sensor system;
an optical system configured to introduce light through a side wall of the tank laterally into the liquid contained in the tank, wherein the tank is configured to cause introduced light to undergo total internal reflection through the liquid contained in the tank, allow the total internal reflection to be frustrated upon an object contacting the liquid contained in the tank through the open front of the tank, and allow at least some of the light undergoing total internal reflection to escape from the tank when the total internal reflection is frustrated; and
an image sensor adapted to detect light escaping the tank.
2. The system of claim 1 , wherein the optical system comprises an infrared (IR) emitter disposed adjacent the tank for emitting the light received by the tank.
3. The system of claim 1 , further comprising an isolating surface on which the tank containing the liquid is disposed, wherein the optical system comprises an IR emitter disposed beneath the isolating surface for emitting IR light; and an optical device for redirecting the emitted IR light into the tank, the light received by the tank being the redirected IR light.
4. The system of claim 3 , wherein the optical device is a right-angle prism disposed adjacent to a side of the tank.
5. The system of claim 3 , wherein the optical device is a mirror disposed adjacent to a side of the tank.
6. The system of claim 1 , wherein the object is a finger of a person.
7. The system of claim 1 , wherein the tank is configured to allow the total internal reflection to be frustrated upon multiple objects contacting the liquid within the tank at multiple locations so that the total internal reflection is frustrated at said multiple locations.
8. The system of claim 7 , wherein the multiple objects are first and second fingers of a person.
9. The system of claim 1 , wherein the image sensor is adapted to discriminately detect light escaping from a bottom surface of the tank.
10. The system of claim 1 , wherein the optical system comprises a light source adapted to emit light of predetermined wavelengths; wherein the tank is adapted to receive the light emitted by the light source, and the image sensor is adapted to detect light only substantially at the predetermined wavelengths.
11. The system of claim 1 , further comprising a diffuser disposed beneath the tank and a projector for projecting a two-dimensional video image onto the diffuser, the tank and the liquid therein being adapted to allow the video image projected onto the diffuser to be seen through the tank.
12. The system of claim 1 , wherein the image sensor comprises a plurality of image sensors adapted to detect light escaping from respectively different portions of the tank.
13. The system of claim 1 , further comprising a liquid crystal display (LCD) panel disposed between the image sensor and a bottom of the tank for displaying a video image, the video image being viewable through the tank, and the LCD panel being transparent to light escaping the tank so as to not prevent the escaping light from being detected by the image sensor.
14. The system of claim 1 , wherein the image sensor is adapted to detect splashes in the liquid contained in the tank based on light escaping the tank when the user splashes the liquid contained in the tank.
15. The system of claim 1 , wherein the tank is configured to allow a user to reach through the liquid contained in the tank to the bottom wall of the tank.
16. A method of multi-touch sensing, comprising the steps of:
introducing, by an optical system, light through a side wall of a tank laterally into liquid contained in the tank, the tank comprising side walls and a bottom wall and having an open front that exposes the liquid contained in the tank to a user;
internally reflecting light through the liquid within the tank, the tank being configured to cause introduced light to undergo total internal reflection through the liquid contained in the tank;
frustrating, upon an object contacting the liquid contained in the tank through the open front of the tank, the internally reflected light within the tank to cause some of the reflected light to escape the tank, the tank being configured to allow the total internal reflection to be frustrated upon the object contacting the liquid contained in the tank through the open front of the tank and allow at least some of the light undergoing total internal reflection to escape from the tank when the total internal reflection is frustrated; and
imaging the escaped light.
17. The method of claim 16 , comprising emitting the light received by the tank by an IR emitter, the IR emitter disposed adjacent the tank.
18. The method of claim 16 , comprising disposing the tank on an isolating surface; emitting IR light by an IR emitter disposed beneath the isolating surface; and
redirecting the emitted IR light into the tank, the received light within the tank being the redirected IR light.
19. The method of claim 18 , wherein redirecting the emitted IR light is carried out by a right-angle prism disposed adjacent to a side of the tank.
20. The method of claim 18 , wherein redirecting the emitted IR light is carried out by a mirror disposed adjacent to a side of the tank.
21. The method of claim 16 , wherein frustrating the internally reflected light comprises contacting the liquid within the tank with a finger of a person.
22. The method of claim 16 , wherein frustrating the internally reflected light comprises frustrating the internally reflected light simultaneously at a plurality of positions by contacting with multiple objects the liquid within the tank.
23. The method of claim 22 , wherein the multiple objects are first and second fingers of a person.
24. The method of claim 16 , wherein imaging the escaped light comprises imaging discriminately light escaping from a bottom surface of the tank.
25. The method of claim 16 , wherein introducing light comprises introducing light of a predetermined wavelength, and imaging the escaped light comprises imaging light only substantially at the predetermined wavelength.
26. The method of claim 16 , comprising projecting a two-dimensional video image onto a diffuser disposed beneath the tank, the projected video image being viewable through the tank.
27. The method of claim 16 , wherein imaging the escaped light comprises imaging by a plurality of image sensors light escaping from respectively different portions of the tank.
28. The method of claim 16 , comprising disposing an LCD panel beneath the tank, and displaying a video image by the LCD panel, the display video image being viewable through the tank, and the LCD panel being transparent to the escaped light.