Probabilistic Latency Modeling

• US 20120188197A1
• Filed: 08/08/2011
• Published: 07/26/2012
• Est. Priority Date: 01/24/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Uzelac, Aleksandar, Stevens, David A., Zhao, Weidong, Shigemitsu, Takahiro, Willoughby, Briggs A., Pierce, John Graham, Santiago, Pravin Kumar, Ranta, Craig S., Wright, Timothy Allen, Maier, Jeffrey C., Perry, Robert T., Kirilov, Stanimir Naskov, Batchvarov, Andrey B.
• Granted Patent: US 9,030,437 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 11/2221 to test input/output devices or peripheral units
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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

Touchscreen testing techniques are described. In one or more implementations, a piece of conductor (e.g., metal) is positioned as proximal to a touchscreen device and the touchscreen device is tested by simulating a touch of a user. This technique may be utilized to perform a variety of different testing of a touchscreen device, such as to test latency and probabilistic latency. Additional techniques are also described including contact geometry testing techniques.

Claims

1. A method implemented by one or more computing devices, the method comprising:

modeling latency of a touchscreen device using parameterized statistics by;

obtaining data describing end-to-end latency measurements of the touchscreen device to recognize a touch input; and

fitting the data to parametric distributions.

2. A method as described in claim 1, wherein the latency is modeled using a random variable with known distribution.

3. A method as described in claim 1, wherein the latency is modeled using the following expression:

L=U_{[0,1Hardware]}+U_[0,1Bus]+f_{INPUT STACK}+U_{[0,1GRAPHICS]}+f_SCREEN

where U[a, b] stands for uniform distribution in range [a, b], and fc stands for a fixed parameter describing c.

4. A method as described in claim 3, wherein U_{[0,1Hardware]} describes a scanning rate of the touchscreen device and U_[0,1Bus] describes latency distribution of a USB connection.

5. A method as described in claim 1, wherein the obtaining of the data includes:

placing a conductor that is disposed proximal to the touchscreen device in a grounded state;

receiving a report from the touchscreen device indicating a point in time at which the touch input was detected by the touchscreen device; and

computing the time delay by comparing the point in time at which the touch input was detected by the touchscreen device with a point in time at which the conductor was placed in the grounded state

6. A method as described in claim 5, wherein the obtaining of the data includes:

placing the conductor that is disposed proximal to the touchscreen device in an ungrounded state;

receiving a report from the touchscreen device indicating a point in time at which a lack of the touch input was detected by the touchscreen device; and

computing the time delay by comparing the point in time at which the lack of the touch input was detected by the touchscreen device with a point in time at which the conductor was placed in the ungrounded state

7. A method as described in claim 6, wherein the placing of the conductor in the grounded state emulates a touch by a user and further comprising placing the conductor in an ungrounded state while the conductor is still disposed proximal to the digitizer to emulate a lack of the touch input on the computing device.

8. A method as described in claim 5, further comprising synchronizing a clock on the one or more computing devices that is utilized to indicate the point in time at which the conductor was placed in the grounded state with a clock of the touchscreen device that is utilized to indicate the point in time at which the touch input was detected by the touchscreen device.

9. A method as described in claim 5, wherein the placing is performed using an electrical switch driven by the one or more computing devices.

19. An apparatus as described in claim 9, wherein the calculation involves the following expression to model end-to-end latency, L_E2E=d/v, where d is distance between the coordinates, v is average velocity, and L_E2E is the end-to-end latency.

20. An apparatus as described in claim 9, wherein the coordinate of the item as displayed by the touchscreen device at the recorded point in time is specified by a timestamp from a clock of the touchscreen device.

10. A method comprising:

displaying a moving item by a touchscreen device;

receiving data that describes one or more touch inputs that are to follow the display of the moving item; and

calculating end-to-end latency of the touchscreen device to recognize the touch input from the data and data describing the display of the moving item.

11. A method as described in claim 10, wherein the data describes one or more touch inputs received through detecting a part of a user'"'"'s body by the touchscreen device.

12. A method as described in claim 10, wherein the touchscreen device uses capacitive sensors.

13. A method as described in claim 10, wherein the calculating compares velocity of the display of the moving item with velocity of the one or more touch inputs.

14. A method as described in claim 10, wherein the calculating compares variance of the one or more touch inputs with the display of the moving item.

15. A method as described in claim 10, wherein the calculating includes computing a distance between a position at which the item is displayed and a position at which the touch input is received at a particular point in time.

16. A method as described in claim 15, wherein the calculating involves the following expression to model the end-to-end latency, L_E2E=d/v, where d is distance, v is average velocity, and L_E2E is the end-to-end latency.

17. A method as described in claim 10, wherein the calculating includes analyzing the data to find a model that represents the data.

18. An apparatus comprising:

a clock; and

one or more modules communicatively coupled to the clock, the one or more modules configured to;

cause an item to be displayed by a touchscreen device;

record a point in time from the clock at which the causing occurred; and

calculate a latency of the touchscreen device using data that describes a point in time at which the touch input was detected by the touchscreen device, a coordinate on the touchscreen device of the touch input, the recorded point in time, and a coordinate of the item as displayed by the touchscreen device at the recorded point in time.