Black image insertion for capacitive sensing
View Patent ↗When performing capacitive sensing, a modulated signal is driven on transmitter electrodes located only within a black image of the display device. When updating a display screen based on a newly received display frame, an input device may first insert the black image on the display screen. Once the black image is displayed, the input device may use the electrodes within the area of the screen displaying the black image to track the input object using capacitive sensing (e.g., determine if the user is pressing a finger or stylus on the screen). In this manner, performing capacitive sensing affects only the pixels displaying the black image which is not perceived by the user. After performing capacitive sensing using the electrodes, the input device may replace the black image with display data from the new display frame.
1. A method comprising:
transmitting a first display image for display on a first portion of a display screen of a display device;
transmitting a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen;
identifying a transmitter electrode located substantially within the first portion of the display screen; and
driving, using a processor, a signal used for capacitive sensing on the identified transmitter electrode to determine positional information only upon determining that the black image is displayed in the first portion of the display screen.
2. The method of claim 1 , wherein the first display image is a full display frame of the display screen comprising all of the display lines of the display screen.
3. The method of claim 1 , wherein the black image is a black frame comprising all of the display lines of the display screen.
4. A method comprising:
transmitting a first display image for display on a first portion of a display screen of a display device;
transmitting a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen, and wherein the black image is a black band comprising only a subset of the display lines of the display screen;
identifying a transmitter electrode located substantially within the first portion of the display screen;
driving, using a processor, a signal used for capacitive sensing on the identified transmitter electrode to determine positional information when the black image is displayed on the first portion of the display screen; and
updating the first portion of the display screen based on one of the first display image and a second display image thereby removing the black image from the display screen.
5. The method of claim 4 , further comprising:
transmitting for display a second black image at a second portion of the display screen after updating the first portion of the display screen;
identifying a different transmitter electrode located substantially within the second portion of the display screen;
driving the signal on the different transmitter electrode to determine positional information when the black image is displayed on the second portion of the display screen.
6. A method comprising:
transmitting a first display image for display on a first portion of a display screen of a display device;
transmitting a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen;
identifying a transmitter electrode located substantially within the first portion of the display screen; and
driving, using a processor, a signal used for capacitive sensing on the identified transmitter electrode to determine positional information when the black image is displayed on the first portion of the display screen, wherein transmitter electrodes in the display screen located outside of the first portion are not driven using the signal when driving the signal on the identified transmitter electrode.
7. A display device comprising:
a display screen;
a plurality of transmitter electrodes configured for determining positional information using capacitive sensing; and
a processor configured to:
transmit a first display image for display on a first portion of the display screen,
transmit a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen,
identify a first one of the transmitter electrodes located substantially within the first portion of the display screen, and
drive a signal used for capacitive sensing on the first transmitter electrode to determine positional information only upon determining that the black image is displayed in the first portion of the display screen.
8. The display device of claim 7 , wherein the first display image is a full display frame of the display screen comprising all of the display lines of the display screen.
9. The display device of claim 7 , wherein the black image is a black frame comprising all of the display lines of the display screen.
10. A display device comprising:
a display screen;
a plurality of transmitter electrodes configured for determining positional information using capacitive sensing; and
a processor configured to:
transmit a first display image for display on a first portion of the display screen,
transmit a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen, and wherein the black image is a black band comprising only a subset of the display lines of the display screen,
identify a first one of the transmitter electrodes located substantially within the first portion of the display screen,
drive a signal used for capacitive sensing on the first transmitter electrode to determine positional information when the black image is displayed on the first portion of the display screen, and
update the first portion of the display screen based on one of the first display image and a second display image thereby removing the black image from the display screen.
11. The display device of claim 10 , wherein the processor is configured to:
transmit for display a second black image at a second portion of the display screen after updating the first portion of the display screen;
identify a second one of the transmitter electrodes located substantially within the second portion of the display screen;
drive the signal on the second transmitter electrode to determine positional information when the black image is displayed on the second portion of the display screen.
12. A display device comprising:
a display screen;
a plurality of transmitter electrodes configured for determining positional information using capacitive sensing; and
a processor configured to:
transmit a first display image for display on a first portion of the display screen,
transmit a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen,
identify a first one of the transmitter electrodes located substantially within the first portion of the display screen, and
drive a signal used for capacitive sensing on the first transmitter electrode to determine positional information when the black image is displayed on the first portion of the display screen, wherein transmitter electrodes of the plurality of transmitter electrodes located outside of the first portion are not driven using the signal when driving the signal on the identified transmitter electrode.
13. A processing system for a display device, the processing system comprising:
a display driver module comprising one or more hardware elements configured to update a display screen, the display driver module configured to:
transmit a first display image for display on a first portion of a display screen of a display device, and
transmit a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen; and
transmitter circuitry configured to:
identify a transmitter electrode located substantially within the first portion of the display screen, and
drive a signal on the identified transmitter electrode used for capacitive sensing to determine positional information only upon determining that the black image is displayed in the first portion of the display screen.
14. The processing system of claim 13 , wherein the first display image is a full display frame of the display screen comprising all of the display lines of the display screen.
15. A processing system for a display device, the processing system comprising:
a display driver module comprising one or more hardware elements configured to update a display screen, the display driver module configured to:
transmit a first display image for display on a first portion of a display screen of a display device, and
transmit a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen; and wherein the black image is a black band comprising only a subset of the display lines of the display screen; and
transmitter circuitry configured to:
identify a transmitter electrode located substantially within the first portion of the display screen,
drive a signal on the identified transmitter electrode used for capacitive sensing to determine positional information when the black image is displayed on the first portion of the display screen,
wherein the display driver module is configured to:
update the first portion of the display screen based on one of the first display image and a second display image thereby removing the black image from the display screen.
16. The processing system of claim 15 , wherein display driver module is configured to transmit for display a second black image at a second portion of the display screen after updating the first portion of the display screen, and
wherein the transmitter circuitry is configured to:
identify a different transmitter electrode located substantially within the second portion of the display screen, and
drive the signal on the different transmitter electrode to determine positional information when the black image is displayed on the second portion of the display screen.
17. A processing system for a display device, the processing system comprising:
a display driver module comprising one or more hardware elements configured to update a display screen, the display driver module configured to:
transmit a first display image for display on a first portion of a display screen of a display device, and
transmit a black image for display on the first portion of the display screen after outputting the first display image, wherein the black image comprises a plurality of contiguous display lines of the display screen; and
transmitter circuitry configured to:
identify a transmitter electrode located substantially within the first portion of the display screen, and
drive a signal on the identified transmitter electrode used for capacitive sensing to determine positional information when the black image is displayed on the first portion of the display screen, wherein transmitter electrodes in the display screen located outside of the first portion are not driven using the signal when driving the signal on the identified transmitter electrode.