TOUCH SCREEN FOR STYLUS EMITTING WIRELESS SIGNALS

• US 20150338950A1
• Filed: 05/22/2014
• Published: 11/26/2015
• Est. Priority Date: 05/22/2014
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Noviello, Giuseppe, Ningrat, Kusuma Adi
• Granted Patent: US 9,454,272 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A touch screen device is configured with rows of conductors capable of receiving wireless signals from a stylus. When the stylus touches the touch screen, the stylus emits multiple wireless signals in different directions. The conductors receiving the emitted wireless signals provide the signals to circuitry that filters, amplifies, and digitizes the wireless signals, as received at each conductor. The magnitude of each conductor'"'"'s received wireless signal is computed, and the computed magnitudes are used to determine the location of the stylus on the touch screen surface. The stylus is assumed to be closer to conductors receiving stronger signals than those receiving weaker signals.

Claims

1. A touch screen device, comprising:

a touch screen with a plurality of conductors configured to receive wireless signals from a stylus touching the touch screen;

a circuit configured to generate amplified and digitized representations of the wireless signals; and

a processor configured to determine magnitudes of the wireless signals at each of the plurality of conductors receiving the wireless signals based on the amplified and digitized representations and use the magnitudes of the wireless signals at each of the plurality of conductors to determine a location of the stylus on the touch screen.

2. The touch screen device of claim 1, further comprising memory storing instructions that enable the processor to perform an algorithmic transform on the amplified and digitized representations of the wireless signals.

3. The touch screen device of claim 2, wherein the algorithmic transform comprises a fast Fourier transform.

4. The touch screen device of claim 1, wherein the processor determines the location of the stylus by calculating a relative strength value based on the magnitudes of the wireless signals and using the relative strength value to indicate at least one of the plurality of conductors.

5. The touch screen device of claim 1, wherein the processor decodes data in the wireless signals by setting significance of bits associated with each of the wireless signals based on transmission frequencies of the wireless signals and deciphering assertion values for each of the wireless signals.

6. The touch screen device of claim 5, wherein the data comprises an indication of at least one member of a group comprising a stylus identifier, stylus touch pressure on the touch screen, and stylus inclination relative to the touch screen.

7. The touch screen device of claim 1, wherein the plurality of conductors comprise a first group of conductors spanning one direction of the touch screen and a second group of conductors spanning a perpendicular direction of the touch screen.

8. The touch screen device of claim 7, wherein the first group of conductors are configured to receive the wireless signals, and the second group of conductors are configured to detect changes in capacitance caused by stylus or finger touches of the touch screen.

9. The touch screen device of claim 7, wherein the first and second groups of conductors are configured to receive the wireless signals from the stylus.

10. A method for determining the location, on a touch screen, of a stylus in contact with the touch screen, comprising:

receiving, at touch screen conductors, wireless signals from the stylus when the stylus touches the touch screen;

determining magnitudes of the wireless signals received by the touch screen conductors;

determining the location of the stylus based on the magnitudes of the wireless signals; and

storing the location of the stylus.

11. The method of claim 10, wherein the magnitudes of the received wireless signals are determined after the wireless signals are amplified and digitized.

12. The method of claim 11, further comprising filtering the wireless signals using a band-pass filter before amplification and digitization.

13. The method of claim 11, further comprising performing an algorithmic transform on the amplified and digitized wireless signals to determine the magnitudes of the wireless signals received by the touch screen conductors.

14. The method of claim 10, further comprising using the stored location of the stylus to change content displayed on the touch screen.

15. The method of claim 10, further comprising deciphering data embedded in the wireless signals indicative of at least one attribute associated with the stylus.

16. A system, comprising:

a stylus configured to emit a plurality of wireless signals of different frequencies when in contact with a touch screen surface; and

a touch screen device comprising receiving conductors, a touch screen surface, a processor, and an analog-to-digital converter (ADC), wherein the touch screen is configured to;

receive the plurality of wireless signals with the receiving conductors,

produce sampled wireless signals based on the plurality of wireless signals received by the receiving conductors;

use the ADC to digitize the sampled wireless signals,

determine magnitudes associated with digital representations of the sampled wireless signals as received by the receiving conductors, and

determine a location of the stylus on the touch screen based on the magnitudes associated with the digital representations of the sampled wireless signals as received by the receiving conductors.

17. The system of claim 16, wherein the touch screen device determines the magnitudes associated with the digital representations of the sampled wireless signals by applying an algorithmic transform to the digital representations.

18. The system of claim 16, the touch screen device further comprises capacitive touch conductors spanning the touch screen surface in a perpendicular direction to the receiving conductors, wherein the capacitive touch conductors are configured to detect touches on the touch screen surface through changes in capacitance.

19. The system of claim 16, wherein the touch screen device further comprises amplifier circuitry configured to amplify the wireless signals as received by the receiving conductors before the digitization by the ADC.

20. The system of claim 16, wherein the wireless signals comprise multiple sets of wireless signals and the processor is configured to compare magnitudes generated for each of the sets of wireless signals and discard one of the sets based on the comparison.