Color sensor arrangement and method for color sensor calibration

Patent metadata

Field	Value
Publication number	US-10072981-B2
Application number	US-201415027239-A
Country	US
Kind code	B2
Filing date	Sep 24, 2014
Priority date	Oct 4, 2013
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A color sensor arrangement comprises a color sensor arranged to generate at least a first channel signal being indicative of a color of light incident on the color sensor. A processing unit is connected to the color sensor and arranged to generate a tuple of color signals by processing the at least first channel signal. A memory is connected to the processing unit and a control unit is connected to the processing unit and to the memory. Furthermore, the control unit is arranged to receive calibration data relating the tuple of color signals to a calibrated tuple of color signals and arranged to store said calibration data (M) by means of the memory. An interface is connected to the processing unit and comprises an interface terminal.

First claim

The invention claimed is:

1. A color sensor arrangement, comprising:
a color sensor implemented on a chip and configured to generate at least a first channel signal being indicative of a color of light incident on the color sensor;
a processing unit implemented on the chip and connected to the color sensor and configured to generate a tuple of color signals by processing the at least first channel signal;
a memory implemented on the chip and connected to the processing unit;
a control unit implemented on the chip and connected to the processing unit and to the memory, and configured to receive calibration data relating the tuple of color signals to a calibrated tuple of color signals and configured to store the calibration data by means of the memory; and
an interface connected to the processing unit and comprising an interface terminal,
wherein the calibration data is for calibration of the color sensor and is characteristic of the color sensor, and the memory is configured to store the calibration data on the color sensor.

2. The color sensor arrangement according to claim 1 , wherein the control unit is configured to receive the calibration data via the interface.

3. The color sensor arrangement according to claim 1 , wherein the memory is configured to be read out by an external component or by a dedicated unit of the color sensor arrangement and to provide the calibration data to perform color transformation.

4. The color sensor arrangement according to claim 1 , wherein the color sensor comprises an array of photo-elements.

5. The color sensor arrangement according to claim 1 , wherein the color sensor comprises:
a first photo-diode configured to generate the first channel signal;
a second photo-diode configured to generate a second channel signal;
a third photo-diode configured to generate a third channel signal;
a fourth photo-diode configured to generate a fourth channel signal; and
the processing unit is configured to generate the tuple of color signals by processing the first, second, third and fourth channel signals.

6. The color sensor arrangement according to claim 5 , wherein the color sensor is covered by an infrared blocking filter, and
wherein the first, second, and third photo-diodes are covered by a first, second and third filter, respectively.

7. The color sensor arrangement according to claim 5 , wherein the processing unit comprises:
a multi-channel integrating analog-to-digital converter connected to the color sensor for receiving the at least first channel signal; and
a data register connected to the multi-channel integrating analog-to-digital converter for storing the at least a first integrated channel signal.

8. The color sensor arrangement according to claim 7 , wherein the multi-channel integrating analog-to-digital converter is further configured for receiving the second, third and fourth channel signals, and
wherein the data register is further configured for storing a second, third and fourth integrated channel signals.

9. The color sensor arrangement according to claim 1 , wherein the processing unit comprises an arithmetic unit connected to the memory, and configured to read the calibration data from the memory and transform the tuple of color signals into the calibrated tuple of color signals depending on the calibration data.

10. The color sensor arrangement according to claim 9 , wherein the control unit is connected to the interface terminal and is configured to initialize a calibration mode of the color sensor arrangement depending on whether a calibration signal is applied to the interface terminal.

11. The color sensor arrangement according to claim 10 , wherein, in the calibration mode, the control unit receives the calibration data via the interface terminal and writes the calibration data into the memory.

12. The color sensor arrangement according to claim 10 , wherein, in the calibration mode, the arithmetic unit computes the calibration data from the tuple of color signals and depending on a color model and control logic receives the calibration data via the arithmetic unit and writes the calibration data into the memory.

13. The color sensor arrangement according to claim 10 , wherein the interface is configured for bidirectional communication and the control unit is configured for synchronizing the calibration mode to the calibration signal to be applied at the interface terminal.

14. The color sensor arrangement according to claim 1 , wherein during a post-package calibration process, calibration data corresponding to coefficients generated by a color transformation algorithm are stored in the memory.

15. The color sensor arrangement according to claim 1 , wherein the color sensor is configured to be calibrated externally and the interface provides for the calibration data to be stored in the memory, wherein the calibration data is configurable by a manufacturer, and is readable for subsequent use.

16. The color sensor arrangement according to claim 15 , wherein calibration of the color sensor is initiated externally, using the interface, the calibration data and the processing unit.

17. The color sensor arrangement according to claim 1 , wherein the processing unit is configured to integrate the first channel signal for a predefined period of time.

18. The color sensor arrangement according to claim 17 , wherein a number of counts per the predefined period of time corresponds to measurements of at least one of signal strength or brightness.

19. A method for color sensor calibration, comprising the steps of:
generating at least a first channel signal by means of a color sensor of a color sensor arrangement, the color sensor implemented on a chip, the at least first channel signal being indicative of a color of light reflected and/or emitted from a calibration source;
generating a tuple of color signals by processing the at least first channel signal;
determining calibration data relating the tuple of color signals to a color model; and
writing the calibration data into a memory wherein the memory is comprised by the color sensor arrangement and is implemented on the chip,
wherein the calibration data is for calibration of the color sensor and is characteristic of the color sensor, and the memory is configured to store the calibration data on the color sensor,
wherein testing corresponding to the calibration is performed in a controlled environment, for reduced device-to-device tolerance, and
wherein a particular output can be calculated by a customer without requiring a tristimulus matrix transformation, based on the calibration data tracking with the color sensor arrangement.

20. The method according to claim 19 , wherein the calibration source comprises a calibration light source.

21. The method according to claim 19 , wherein the tuple of color signals is read by an external processing means.

22. The method according to claim 19 , wherein the tuple of color signals is input to an arithmetic unit comprised by the color sensor arrangement, and
wherein the calibration data is determined by means of the arithmetic unit and depending on a color model.

Assignees

• Ams Ag

Inventors

• Lee Glenn

Classifications

• G01J3/0213

  using attenuators · CPC title

• G01J3/513

  having fixed filter-detector pairs · CPC title

• G01J3/462

  Computing operations in or between colour spaces; Colour management systems · CPC title

• G01J3/0297 Primary

  Constructional arrangements for removing other types of optical noise or for performing calibration · CPC title

• G01J3/505

  measuring the colour produced by lighting fixtures other than screens, monitors, displays or CRTs · CPC title