Electronic device with resistive sensor array

• US 10,295,612 B2
• Filed: 10/24/2016
• Issued: 05/21/2019
• Est. Priority Date: 04/05/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Guo, Jian
• Primary Examiner(s): McAndrew, Christopher P
• Application Number:
  US15/332,119
• Publication Number:
  US 20170285082A1
• Time in Patent Office: 939 Days
• Field of Search: 324691
• CPC Class Codes: G01D 5/165 by relative movement of a point of contact or actuation and a resistive track
• CPC Class Codes: G01R 27/14 Measuring resistance by measuring current or voltage obtained from a reference source G01R27/16, G01R27/20, G01R27/22 take precedence
• CPC Class Codes: G01R 33/0023 Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration G01R33/0017 takes precedence
• CPC Class Codes: G01R 33/0094 Sensor arrays
• CPC Class Codes: G01R 33/09 Magnetoresistive devices

Abstract

An array of resistive sensor circuits may be used to gather sensor data. Each resistive sensor circuit may have a resistive sensor and an associated switch. Row decoder circuitry may supply rows of the sensor circuits with control signals on row lines. Capacitors associated with respective columns of the array may be provided with an initialization voltage. The control signals on the row lines may be used to turn on the switches in a selected row of the resistive sensor circuits and thereby discharge the capacitors through the resistive sensors of that row. Comparators may have first inputs coupled to the capacitors and second inputs that receive a reference voltage. A column readout circuit may have memory and processing circuitry that receives count values from a counter and that stores the count values in response to toggling output signals from the comparators.

Claims

1. Resistive sensor circuitry, comprising:

an array of resistive sensors having rows and columns, wherein the array of resistive sensors are configured to make ambient air measurements; and

resistive sensor array control circuitry including row decoder circuitry that is configured to select a row of the array and column readout circuitry that gathers resistive sensor measurements from each of the resistive sensors in the selected row, wherein the column readout circuitry further comprises;

memory cells, each of which is coupled to a respective column of resistive sensors in the array; and

a counter that provides the memory cells with a count value.

2. The resistive sensor circuitry defined in claim 1 wherein the column readout circuitry includes capacitors and wherein each of the capacitors discharges through a respective one of the resistive sensors in the selected row.

3. The resistive sensor circuitry defined in claim 2 wherein the column readout circuitry includes comparators.

4. The resistive sensor circuitry defined in claim 3 wherein each column of the array has an associated column line and wherein each of the capacitors discharges through a respective one of the resistive sensors in the selected row through a respective one of the column lines.

5. The resistive sensor circuitry defined in claim 1, wherein each of the memory cells receives a comparator output signal from a respective one of the comparators and is configured to store the count value when that comparator output signal toggles.

6. The resistive sensor circuitry defined in claim 5 wherein the column readout circuitry further comprises:

a first digital-to-analog converter that produces an initialization voltage; and

a second digital-to-analog converter that produces a reference voltage for the comparators, wherein each of the resistive sensors comprises a resistive sensor selected from the group consisting of;

a pressure sensor, a gas sensor, a magnetic sensor, a force sensor, an acoustic sensor, a temperature sensor, a humidity sensor, and a particulate sensor.

7. The resistive sensor circuitry defined in claim 6 further comprising:

first switching circuitry coupled between the resistive sensors and the column lines, wherein the capacitors discharge through the resistive sensors in the selected row by discharging through the column lines, the first switching circuitry, and the resistive sensors; and

second switching circuitry coupled between the first digital-to-analog converter circuitry and the capacitors that is configured to supply the capacitors with the initialization voltage before the capacitors are discharged through the resistive sensors.

8. Circuitry, comprising:

an array of resistive sensors having rows and columns, wherein each row includes a row line and wherein each column includes a column line, wherein each resistive sensor in the array is coupled to a respective column line via a corresponding first switch;

a row decoder configured to control the first switch associated with each resistive sensor in the array;

capacitors, wherein each capacitor is coupled to a respective one of the column lines at a node; and

second switches each of which is coupled to a respective one of the nodes.

9. The circuitry defined in claim 8 wherein each of the resistive sensors comprises a resistive sensor selected from the group consisting of:

a pressure sensor, a gas sensor, a magnetic sensor, a force sensor, an acoustic sensor, a temperature sensor, a humidity sensor, and a particulate sensor.

10. The circuitry defined in claim 8 further comprising comparators, each comparator having a first input coupled to a respective one of the nodes, having a second input that receives a reference voltage, and having an output.

11. The circuitry defined in claim 10 wherein each of the second switches is configured to supply an initialization voltage to the node coupled to that second switch when that second switch is closed.

12. The circuitry defined in claim 11 further comprising row decoder circuitry that supplies control signals to the first switches through the row lines.

13. The circuitry defined in claim 12 wherein the row decoder circuitry is configured to turn on the first switches in a selected one of the rows so that the capacitors discharge through the resistive sensors in the selected one of the rows.

14. The circuitry defined in claim 13 further comprising:

a counter; and

memory and processing circuitry that stores count values from the counter in the memory and processing circuitry in response to signals from the outputs of the comparators.

15. Resistive sensor circuitry, comprising:

an array of resistive sensor circuits having rows and columns, wherein each resistive sensor circuit has a switch and a resistive sensor having a first terminal coupled to the switch and a second terminal directly connected to a ground line;

capacitors each of which is associated with one of the columns; and

row decoder circuitry that selectively turns on the switches in a selected one of the rows and thereby discharges the capacitor in each column through the resistive sensor that is in the selected row and that is in that column.

16. The resistive sensor circuitry defined in claim 15 wherein each of the resistive sensors comprises a resistive sensor selected from the group consisting of:

a pressure sensor, a gas sensor, a magnetic sensor, a force sensor, an acoustic sensor, a temperature sensor, a humidity sensor, a particulate sensor, and a light sensor.

17. The resistive sensor circuitry defined in claim 16 further comprising at least one heater that heats at least one of the resistive sensors.

18. The resistive sensor circuitry defined in claim 16 further comprising comparators each of which has a first input coupled to a respective one of the capacitors and each of which has a second input that receives a reference voltage.

19. The resistive sensor circuitry defined in claim 18 further comprising a circuit that receives count values from a counter and that stores the count values in response to signals from the comparators.