Authenticity feature in the form of luminescent substances

1. A checking method for verifying a security element, the method comprising the steps:

providing the security element that includes

a first luminescent substance having a first emission spectrum; and

a second luminescent substance having a second emission spectrum, wherein

the first emission spectrum and the second emission spectrum each include at least one substantially identical joint emission band,

the first luminescent substance has at least a first excitation band and a second excitation band that each produces an emission at the joint emission band,

the second luminescent substance has at least a first excitation band that produces an emission at the joint emission band, and

the first excitation band of the first luminescent substance is different than the first excitation band of the second luminescent substance;

illuminating the luminescent substances with a first radiation which has a wavelength lying substantially at the first excitation band of the first luminescent substance;

detecting the emission at the substantially identical joint emission band;

illuminating the luminescent substances with a second radiation which has a wavelength lying substantially at the first excitation band of the second luminescent substance; and

detecting the emission at the substantially identical joint emission band.

2. A security element comprising:

a first luminescence system, which includes a combination of first and second luminophores, and

a second luminescence system, which includes a combination of third and fourth luminophores, wherein

the first luminophor of the first luminescence system has a first emission spectrum and the third luminophor of the second luminescence system has second emission spectrum, wherein the first emission spectrum and the second emission spectrum overlap at least at one substantially identical joint emission band, and

the first luminophor has a first excitation spectrum and the third luminophor has a second excitation spectrum, wherein

the first excitation spectrum has at least a first excitation band and a second excitation band that each produce an emission of the first luminophor at the joint emission band,

the second excitation spectrum has at least a first excitation band and a second excitation band that each produce an emission of the third luminophor at the joint emission band;

the first excitation band of the first excitation spectrum is different than the first excitation band of the second excitation spectrum; and

the second excitation band of the first excitation spectrum is substantially identical to the second excitation band of the second excitation spectrum.

3. The security element of claim 2 , wherein the first and second excitation bands of the excitation spectrum of the first luminophor do not overlap.

4. The security element of claim 2 , wherein first and second luminescent systems have a complete or partial spatial overlap.

5. The security element of claim 2 , wherein each of the first and the second luminescent systems can be excited individually.

6. The security element of claim 2 , wherein illumination of the security element with radiation

at the first excitation band of the excitation spectrum of the first luminophor;

at the first excitation band of the excitation spectrum of the third luminophor; and

at the second excitation band of the first and third luminophores;

results in a luminescence intensity of the first luminophor at the joint emission band at a predetermined intensity relation to a luminescence intensity of the third luminophor at the joint emission band.

7. The security element of claim 2 , wherein illumination of the security element with radiation

at the first excitation band of the excitation spectrum of the first luminophor;

at the first excitation band of the excitation spectrum of the third luminophor; and

at the second excitation band of the first and third luminophores;

results in a luminescence rise and/or decay time of the first luminophor at the joint emission band at a predetermined temporal relation to a luminescence rise and/or decay time of the third luminophor at the joint emission band.

8. The security element of claim 2 , wherein illumination of the security element with radiation

at the first excitation band of the excitation spectrum of the first luminophor;

at the first excitation band of the excitation spectrum of the third luminophor; and

at the second excitation band of the first and third luminophores;

results in a luminescence spectral shape of the first luminophor at the joint emission band at a predetermined relation to a luminescence spectral shape of the third luminophor at the joint emission band.

9. A value document comprising the security element according to claim 2 , wherein the value document comprises at least one of paper and plastic.

10. The value document of claim 9 , wherein the first luminescence system and the second luminescence system are independently applied to the value document.

11. An authentication method for verifying a presence of the security element according to claim 2 , comprising at least two of the following steps:

jointly exciting the first luminophor and the third luminophor with a first radiation, which has a wavelength which is substantially included in the second excitation band of the first and the second excitation spectrum, and detecting a first emission at the joint emission band;

individually exciting the first luminophor with a second radiation, which has a wavelength which is substantially included in the first excitation band of the first excitation spectrum and detecting a second emission at the joint emission band;

individually exciting the third luminophor with a third radiation, which has a wavelength which is substantially included in the first excitation band of the second excitation spectrum and detecting a third emission at the joint emission band; and

relating the properties of the detected first, second, and third emission at the joint emission band.

12. The authentication method of claim 11 , further comprising:

jointly exciting the first luminophor and the second luminophor with a combined radiation of at least two of the first radiation, the second radiation, and the third radiation,

and detecting a fourth emission at the joint emission band.

13. The authentication method of claim 11 , further comprising:

selectively exciting the third luminophor and/or the fourth luminophor, and detecting the properties of the resulting emission.

14. The authentication method of claim 11 , wherein the luminescence intensities of the detected emissions are related for authentication.

15. An authentication method of claim 11 , wherein the exciting radiation is time-modulated and luminescence rise times or luminescence decay times of the detected emissions are related for authentication.

16. The authentication method of claim 11 , wherein spectral shapes of the detected emissions are related for authentication.

17. A sensor system for the authentication of value documents according to claim 9 , comprising two independent sensors, wherein each sensor is configured to detect a separate luminescence system.

18. The sensor system of claim 17 , wherein the first sensor is configured to illuminate the value documents with excitation radiation in at least a first and a second wavelength band;

the second sensor is configured to illuminate the value documents with excitation radiation in at least a first and a third wavelength band;

and wherein the second wavelength band and the third wavelength band are different from each other.

19. A sensor system for the authentication of value documents according to claim 9 , comprising an independent sensor and a combination sensor, wherein the independent sensor is configured to only detect one luminescence system and the combination sensor stores and/or collects information about both luminescence systems.

20. The sensor system of claim 19 , wherein the independent sensor is configured to illuminate the value documents with excitation radiation in at least a first and a second wavelength band and the combination sensor is configured to illuminate the value documents with excitation radiation in at least a first, second and third wavelength band.

21. The sensor system of claim 19 , wherein the combination sensor is configured to excite and evaluate both luminescence systems separately or jointly.

22. The sensor system of claim 17 , wherein at least one sensor type illuminates the value documents in different sensor tracks with radiation of different wavelength and/or different time-modulation.