Object location determination including writing pressure information of a stylus

• US 9,229,583 B2
• Filed: 05/29/2013
• Issued: 01/05/2016
• Est. Priority Date: 05/29/2013
• Status: Active Grant

• Current Assignee: Otter Products LLC
• Original Assignee: Otter Products LLC
• Inventors: Spears, Kurt E
• Primary Examiner(s): Le, Que T
• Application Number:
  US13/904,096
• Publication Number:
  US 20140353467A1
• Time in Patent Office: 951 Days
• Field of Search: 250/206.2, 250/206.1, 250/216, 250/221, 250/234, 250/236, 250/227.13
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0423 using sweeping light beams, e.g. using rotating or vibrating mirror

Abstract

A system for determining a location of an object on a planar surface includes a time-of-flight sensor having sensing elements that provide a field of view for the time-of-flight sensor. The system also includes a mirror attached to the shaft of a motor for reflecting the field of view of the time-of-flight sensor across the planar surface. The system also includes electrical circuitry configured to receive range images from the time-of-flight sensor as the field of view is swept across the planar surface and process the range images to identify the object in at least one of the range images. The electrical circuitry is also configured to calculate a location of the object on the planar surface relative to the motor based on an angle of the shaft associated with the at least one range image and based on a distance of the object from time-of-flight sensor.

Claims

1. A system for determining a location of a stylus on a planar surface, the system comprising:

a time-of-flight sensor having multiple sensing elements that provide a field of view for the time-of-flight sensor;

a motor having a rotating shaft;

a mirror attached to the shaft for reflecting the field of view of the time-of-flight sensor across the planar surface, the reflected field of view being about parallel to the planar surface and sweeping the reflected view across the planar surface when the shaft is rotated;

a stylus having a pressure sensitive tip, a switch, and a wireless transmitter, the stylus configured to transmit a wireless signal from the wireless transmitter when the switch is an on position and the pressure sensitive tip is pressed against the planar surface, the wireless signal including writing pressure information detected from the pressure sensitive tip; and

electrical circuitry configured to;

receive a plurality of range images from the time-of-flight sensor as the field of view is swept across the planar surface, wherein each range image includes information indicating detected distances associated with content of the range image;

process the plurality of range images to identify at least one of the range images that includes the stylus;

calculate a location of the stylus on the planar surface relative to the motor based on an angle of the shaft associated with the at least one range image and a distance of the stylus from the time-of-flight sensor indicated in the at least one range image;

receive the transmitted wireless signal from the stylus; and

transmit the calculated location of the stylus and the writing pressure information to a display system.

2. The system of claim 1 wherein the motor is a stepper motor.

3. The system of claim 1 wherein the time-of-flight sensor is a linear sensor having the multiple sensing elements configured in a linear arrangement such that the reflected field of view of the linear sensor is about perpendicular to the planar surface for a plurality of rotational angles of the shaft of the motor.

4. The system of claim 3 wherein the linear sensor is attached to the shaft of the motor and rotates with the shaft of the motor to maintain the perpendicular relationship between the reflected field of view and the planar surface for the plurality of rotational angles.

5. The system of claim 1 wherein the time-of-flight sensor is an area sensor.

6. The system of claim 1 wherein the time-of-flight sensor is a time-of-flight camera.

7. The system of claim 1 wherein the wireless signal comprises infrared light.

8. The system of claim 1 further comprising a lens to collimate the reflected field of view.

9. The system of claim 1 further comprising a calibration marker at a fixed calibration position, the electrical circuitry further configured to process the plurality of range images to determine when the mirror is pointed at the calibration marker and determine the angle of the shaft based on the calibration position.

10. The system of claim 1 further comprising a rotary encoder attached to the shaft of the motor, the electrical circuitry further configured to calibrate the angle of the shaft based on information obtained from the rotary encoder.

14. The system of claim 1 wherein the wireless signal comprises radio frequency signals.

11. A method of determining coordinates of a stylus on a planar surface, the method comprising:

rotationally sweeping a collimated field of view of a time-of-flight sensor across the planar surface, wherein an axis of the rotational sweeping is perpendicular to the planar surface and the field of view is parallel to the planar surface;

receiving a plurality of images from the time-of-flight sensor, each image associated with a different angle of rotation;

processing the plurality of images to identify one of the images that includes the stylus;

determining a distance from the stylus to the time-of-flight sensor based on the one image;

receiving a wireless signal from the stylus indicating that the stylus is being pressed against the planar surface, the wireless signal further indicating a pressure with which the stylus is being pressed against the planar surface as determined by a pressure sensitive tip of the stylus;

calculating the coordinates of the stylus on the planar surface based on;

the distance, a known location of the time-of-flight sensor, and an angle of the sensor associated with the one image; and

transmitting the coordinates and the pressure to a display system.

12. The method of claim 11 wherein the time-of-flight sensor is a linear sensor or an area sensor.

13. A system for providing input to an electronic display, the system comprising:

a stylus having a pressure sensitive tip, a switch, and a wireless transmitter, the stylus configured to transmit a wireless signal from the wireless transmitter when the switch is an on position and when the pressure sensitive tip is pressed against a surface of the electronic display, the wireless signal including writing pressure information detected using the pressure sensitive tip of the stylus; and

a detection unit removably attached to the electronic display, the detection unit including;

a time-of-flight camera having a collimated field of view;

a motor for rotating the field of view across the surface of the electronic display;

one or more computer processors configured to;

rotate the field of view across the surface of the electronic display, the field of view being about parallel to the surface;

receive a plurality of images from the time-of-flight camera, the plurality of images being associated with different angles of rotation;

process the plurality of images to identify at least one of the images that includes the stylus;

calculate a location of the stylus on the surface relative to the location of the motor based on an angle of the motor associated with the one image and based on a distance of the stylus from the time-of-flight camera as indicated in the one image; and

transmit the calculated location for display on the electronic display.

15. The system of claim 13 wherein the wireless signal comprises radio frequency signals.

16. The system of claim 13 wherein the wireless signal comprises infrared light.