Toothbrush system

1 . A toothbrush device comprising:

a motion sensor arranged to sense motion of the toothbrush device to produce motion data;

a signal analysis unit arranged to analyse the motion data to produce brushing data;

a light source arranged to provide visual feedback of brushing activity to a user; and

a light communication module arranged to transmit the brushing data to an external device using the light source,

wherein the light source comprises a multi-color light emitting diode (LED) which allows different colors to be displayed depending on a state of brushing,

wherein the toothbrush device is arranged to use the multi-color LED to provide the visual feedback to the user regarding the brushing activity during the brushing, and to use the multi-color LED to transmit the brushing data to the external device after the brushing,

wherein the signal analysis unit is arranged to produce a summary of brushing activity during a brushing session, and

wherein the light communication module is arranged to modulate chromaticity of the multi-color LED to transmit the summary of brushing activity to the external device after the brushing.

2 . The toothbrush device of claim 1 , wherein the multi-color LED is arranged to emit visible light.

3 . The toothbrush device of claim 1 , wherein the light source comprises a plurality of multi-color LEDs.

4 . The toothbrush device of claim 1 , wherein the light communication module is arranged to modulate the multi-color LED using color shift keying.

5 . The toothbrush device of claim 1 , wherein the light communication module is arranged to map data bits to colors in a predefined color constellation.

6 . The toothbrush device of claim 5 , wherein the toothbrush device is arranged to transmit calibration data containing the colors in the predefined color constellation.

7 . The toothbrush device of claim 1 , wherein the signal analysis unit is arranged to analyse the motion data to produce data indicating an area of a mouth being brushed.

8 . The toothbrush device of claim 1 , wherein the toothbrush device is arranged to detect an input from the user indicating that the brushing data should be transmitted, and to transmit the brushing data to the external device on detection of the input.

9 . The toothbrush device of claim 1 , wherein the toothbrush device comprises a plurality of multi-color LEDs each of which corresponds to an area of a mouth, and the toothbrush device is arranged to illuminate one of the plurality of multi-color LEDs when the corresponding area of the mouth has been brushed for a predetermined amount of time.

10 . The toothbrush device of claim 1 , wherein the light communication module is arranged to inject white light into the brushing data to be transmitted to reduce an appearance of flickering.

11 . A system comprising:

a toothbrush device, the toothbrush device comprising:

a motion sensor arranged to sense motion of the toothbrush device to produce motion data;

a signal analysis unit arranged to analyse the motion data to produce brushing data;

a light source arranged to provide visual feedback of brushing activity to a user, wherein the light source comprises a multi-color light emitting diode (LED) which allows different colors to be displayed depending on a state of brushing; and

a light communication module arranged to transmit the brushing data to an external device using the multi-color LED,

wherein the toothbrush device is arranged to use the multi-color LED to provide the visual feedback to the user regarding the brushing activity during the brushing, and to use the multi-color LED to transmit the brushing data to the external device after the brushing,

wherein the signal analysis unit is arranged to produce a summary of brushing activity during a brushing session, and

wherein the light communication module is arranged to modulate chromaticity of the multi-color LED to transmit the summary of brushing activity to the external device after the brushing; and

a mobile processing device, the mobile processing device comprising:

a camera arranged to produce image data; and

a processor arranged to process the image data, wherein the processor is arranged to process an image of the multi-color LED of the toothbrush device to obtain the brushing data.

12 . The system of claim 11 , wherein the processor is arranged to map colors in the image data to colors in a predefined color constellation to detect transmitted data.

13 . The system of claim 11 , wherein the processor is arranged to identify an area of interest containing the image of the multi-color LED in the image data.

14 . The system of claim 11 , wherein the mobile processing device is arranged to transmit the brushing data to a backend server.

15 . A method of analysing brushing activity with a toothbrush device, the method comprising:

sensing motion of the toothbrush device to produce motion data;

analysing the motion data to produce brushing data;

using a light source to provide visual feedback to a user regarding brushing activity during brushing, wherein the light source is a multi-color light emitting diode (LED) which displays different colors depending on a state of brushing; and

modulating the multi-color LED with the brushing data, thereby to transmit the brushing data to an external device,

wherein the same multi-color LED is used to provide the visual feedback to the user regarding the brushing activity during the brushing, and to transmit the brushing data to the external device after the brushing,

wherein the method comprises producing a summary of brushing activity during a brushing session, and

wherein chromaticity of the multi-color LED is modulated to transmit the summary of brushing activity to the external device after the brushing.

16 . The method according to claim 15 , further comprising using a mobile processing device with a camera to produce an image of the multi-color LED, and processing the image to obtain the brushing data.