Single-chip multi-stimulus sensor controller

• US 9,069,408 B2
• Filed: 10/17/2013
• Issued: 06/30/2015
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hotelling, Steve Porter, Krah, Christoph Horst, Yousefpor, Marduke, Wilson, Thomas James
• Primary Examiner(s): Lee, Jr., Kenneth B
• Application Number:
  US14/056,841
• Publication Number:
  US 20140043293A1
• Time in Patent Office: 621 Days
• Field of Search: 345/173, 345/174, 345/178, 178/18.03, 178/18.06, 329/304
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• 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 3/0445 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
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12

Abstract

A multi-stimulus controller for a multi-touch sensor is formed on a single integrated circuit (single-chip). The multi-stimulus controller includes a transmit oscillator, a transmit signal section that generates a plurality of drive signals based on a frequency of the transmit oscillator, a plurality of transmit channels that transmit the drive signals simultaneously to drive the multi-touch sensor, a receive channel that receives a sense signal resulting from the driving of the multi-touch sensor, a receive oscillator, and a demodulation section that demodulates the received sense signal based on a frequency of the receive oscillator to obtain sensing results, the demodulation section including a demodulator and a vector operator.

Claims

1. An apparatus for transmitting a plurality of drive signals simultaneously to a sensor, the apparatus comprising:

transmit logic that generates one or more signals;

an oscillator connected to the transmit logic, wherein the transmit logic generates the one or more signals based on a frequency of the oscillator;

one or more digital-to-analog converters (DACs), the one or more DACs receiving the one or more signals from the transmit logic and generating one or more analog signals;

a bus that receives the one or more analog signals from the one or more DACs; and

one or more multiplexers (MUXs) connected to the bus, each MUX selecting one of a plurality of bus signals for transmission to the sensor as a drive signal, wherein the plurality of bus signals includes the one or more analog signals from the one or more DACs.

2. The apparatus of claim 1, wherein the plurality of bus signals includes a first stimulation signal having a first waveform at the same frequency as the oscillator, and a second stimulation signal having second waveform that is an inverted first waveform.

3. The apparatus of claim 1, wherein the plurality of bus signals include at least one of a common voltage signal, the common voltage signal being a direct current (DC) signal, and a ground (GND).

4. The apparatus of claim 1, wherein the plurality of bus signals includes alternating current (AC) signals, and all of the AC signals are received by the bus from a single DAC.

5. The apparatus of claim 1, further comprising a memory, wherein the memory stores data values specifying which one of the one or more bus signals the MUX is to select during a scan of the sensor.

12. The apparatus of claim 1, wherein the plurality of bus signals includes a first stimulation signal having a first frequency matching the frequency of the oscillator and a first phase, and a second stimulation signal having second frequency matching the frequency of the oscillator and a second phase, the second phase different than the first phase.

6. An apparatus for transmitting a plurality of drive signals simultaneously to a sensor, the apparatus comprising:

transmit logic that generates one or more digital signals;

an oscillator connected to the transmit logic, wherein the transmit logic generates the one or more digital signals based on a frequency of the oscillator;

a digital-to-analog converter (DAC) that converts the one or more digital signals into one or more analog signals;

an analog bus that receives the one or more analog signals from the DAC;

a plurality of analog multiplexers (MUXs) connected to the analog bus, each MUX selecting one of a plurality of bus signals of the analog bus for transmission to the sensor as a drive signal, wherein the bus signals include the one or more analog signals from the DAC;

and a plurality of analog output buffers connected to the MUXs, that buffer the selected drive signals for transmission to the sensor.

7. The apparatus of claim 6, wherein the plurality of bus signals includes a first stimulation signal having a first waveform at the same frequency as the oscillator, and a second stimulation signal having second waveform that is an inverted first waveform.

8. The apparatus of claim 6, wherein the bus signals include at least one of a common voltage signal, the common voltage signal being a direct current (DC) signal, and a ground (GND).

9. The apparatus of claim 6, wherein the bus signals include alternating current (AC) signals, and all of the AC signals are received by the analog bus from a single DAC.

10. The apparatus of claim 6, wherein the one or more analog signals are sinusoidal.

11. The apparatus of claim 6, further comprising a memory, wherein the memory stores data values specifying which one of the plurality of bus signals each MUX is to select during a step of a scan of the sensor.

13. The apparatus of claim 6, wherein the plurality of bus signals includes a first stimulation signal having a first frequency matching the frequency of the oscillator and a first phase, and a second stimulation signal having second frequency matching the frequency of the oscillator and a second phase, the second phase different than the first phase.