Security device
First Claim
1. A device comprising:
- a luminescent material having an area, which when stimulated, luminescences to produce luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different from the first wavelength; and
an optically variable structure that receives and through which is transmitted the luminescent radiation of the first and second wavelengths from the luminescent material, the optically variable structure being constructed to control emission from the device of the received luminescent radiation of the first and second wavelengths transmitted through the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, wherein the optically variable structure is not the luminescent material;
the optically variable structure including an area from within which emission of the luminescent radiation of the first wavelength at a first predetermined angle of emission is permitted by the optically variable structure, and emission of the luminescent radiation of the second wavelength at one or both of (1) the first angle of emission and (2) a second predetermined angle of emission, different from the first angle of emission, is permitted by the optically variable structure, andthe optically variable structure being arranged to permit, from the optically variable structure area, the emissivity of said device for luminescent radiation of said first or second wavelengths to change relative to the emissivity of the device for luminescent radiation of the other of the first or second wavelengths with a change in emission angle of luminescent radiation from said device from said first emission angle to said second emission angle.
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Accused Products
Abstract
A security device for authenticating bank notes, documents and other items, comprises a luminescent material for producing luminescent radiation of first and second wavelengths. The security device includes an optically variable structure for controlling emission of luminescent radiation of at least one of the first and second wavelengths from the security device, the security device being arranged to permit, from an area of the optically variable structure, emission of luminescence of the first and second wavelengths from the security device. The optically variable structure causes the relative emissivity of the security device for luminescent radiation of the first and second wavelengths to change with a change in emission angle, so that the security device produces an angle-dependent color shift in the emitted luminescent radiation. The optically variable structure may comprise an optical interference stack that controls transmission of luminescent radiation therethrough in response to the wavelength of luminescent radiation.
39 Citations
106 Claims
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1. A device comprising:
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a luminescent material having an area, which when stimulated, luminescences to produce luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different from the first wavelength; and an optically variable structure that receives and through which is transmitted the luminescent radiation of the first and second wavelengths from the luminescent material, the optically variable structure being constructed to control emission from the device of the received luminescent radiation of the first and second wavelengths transmitted through the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, wherein the optically variable structure is not the luminescent material; the optically variable structure including an area from within which emission of the luminescent radiation of the first wavelength at a first predetermined angle of emission is permitted by the optically variable structure, and emission of the luminescent radiation of the second wavelength at one or both of (1) the first angle of emission and (2) a second predetermined angle of emission, different from the first angle of emission, is permitted by the optically variable structure, and the optically variable structure being arranged to permit, from the optically variable structure area, the emissivity of said device for luminescent radiation of said first or second wavelengths to change relative to the emissivity of the device for luminescent radiation of the other of the first or second wavelengths with a change in emission angle of luminescent radiation from said device from said first emission angle to said second emission angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 76)
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72. A device comprising:
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a luminescent material having an area, which when stimulated, produces luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different to said first wavelength; and an optically variable structure that receives from the luminescent material the luminescent radiation of the first and second wavelengths and that controls emission of the received luminescent radiation of at least one of said first and second wavelengths from the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, wherein the optically variable structure is not the luminescent material, the device being arranged to permit, from within an area of said optically variable structure, emission of luminescent radiation of said first wavelength from said device at a first angle of emission, and to permit, from the optically variable structure area, emission of luminescent radiation of said second wavelength from said device at one or both of (1) said first angle of emission and (2) a second angle of emission, different to said first angle of emission, and said optically variable structure is arranged to cause, from the optically variable structure area, the emissivity of said device for luminescent radiation of said first or second wavelengths to change relative to the emissivity of the device for luminescent radiation of the other of the first or second wavelengths with a change in emission angle of luminescent radiation from said device from said first emission angle to said second emission angle, and wherein said optically variable structure comprises a diffraction structure and a transmissive material spaced from said diffraction structure, and said luminescent material is disposed between said diffraction structure and said transmissive material, wherein said transmissive material is adapted to reflect part of the luminescent radiation produced by said luminescent material towards said diffraction structure and to transmit part of said luminescent radiation therethrough, wherein the intensity of transmitted luminescent radiation is a function of wavelength of said luminescent radiation and angle of emission thereof from said device. - View Dependent Claims (73, 74, 75)
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77. A device comprising:
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a luminescent material having an area, which when stimulated, produces luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different to said first wavelength; and an optically variable structure that receives from the luminescent material the luminescent radiation of the first and second wavelengths and that controls emission of the received luminescent radiation of at least one of said first and second wavelengths from the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, wherein the optically variable structure is not the luminescent material; the device being arranged to permit, from within an area of said optically variable structure, emission of luminescent radiation of said first wavelength from said device at a first angle of emission, and to permit, from the optically variable structure area, emission of luminescent radiation of said second wavelength from said device at one or both of (1) said first angle of emission and (2) a second angle of emission, different to said first angle of emission, and said optically variable structure is arranged to cause, from the optically variable structure area, the emissivity of said device for luminescent radiation of said first or second wavelengths to change relative to the emissivity of the device for luminescent radiation of the other of the first or second wavelengths with a change in emission angle of luminescent radiation from said device from said first emission angle to said second emission angle, and wherein (i) luminescent means comprises a material which luminesces at said first wavelength and a material which luminesces at said second wavelength, and said luminescent material which luminesces at said first wavelength is in the same layer as the luminescent material which luminesces at the second wavelength or said luminescent material which luminesces at said first wavelength is in a different layer to the luminescent material which luminesces at said second wavelength, (ii) the luminescent material which luminesces at said first wavelength has a boundary defining a first predetermined shape, (iii) the luminescent material which luminesces at said second wavelength has a boundary defining a second predetermined shape, and (iv) at least one of the form and size of said second predetermined shape is different to that of said first predetermined shape; and wherein the device includes at least one of (1) luminescent material which extends or is positioned beyond a boundary of said optically variable structure, and (2) a material exhibiting one or more predetermined colour(s) positioned beyond said boundary. - View Dependent Claims (78)
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79. A device comprising:
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a luminescent material having an area, which when stimulated, produces luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different to said first wavelength; and an optically variable structure that receives from the luminescent material the luminescent radiation of the first and second wavelengths and that controls emission of the received luminescent radiation of at least one of said first and second wavelengths from the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, wherein the optically variable structure is not the luminescent material; the device being arranged to permit, from within an area of said optically variable structure, emission of luminescent radiation of said first wavelength from said device at a first angle of emission, and to permit, from the optically variable structure area, emission of luminescent radiation of said second wavelength from said device at one or both of (1) said first angle of emission and (2) a second angle of emission, different to said first angle of emission, and said optically variable structure is arranged to cause, from the optically variable structure area, the emissivity of said device for luminescent radiation of said first or second wavelengths to change relative to the emissivity of the device for luminescent radiation of the other of the first or second wavelengths with a change in emission angle of luminescent radiation from said device from said first emission angle to said second emission angle; and wherein at least a portion of the optically variable structure is transmissive to visible light. - View Dependent Claims (80, 81)
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- 82. A device comprising a luminescent material having an area, which, when stimulated, luminesces to emit luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different from said first wavelength, and an optically variable structure which receives and through which is transmitted the luminescent radiation of the first and second wavelengths from the luminescent material, and which is constructed to control the intensity of emission of the received and transmitted through luminescent radiation from said device with a predetermined angle of emission of said luminescent radiation from said device, based on the wavelength of said luminescent radiation, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, and wherein the optically variable structure is not the luminescent material.
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98. A device comprising:
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a luminescent material having an area, which when stimulated, produces luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different to said first wavelength; and an optically variable structure that receives from the luminescent material the luminescent radiation of the first and second wavelengths and that controls emission from the optically variable structure of the received luminescent radiation of at least one of said first and second wavelengths from the luminescent material, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted from the optically variable structure, wherein the optically variable structure is not the luminescent material; the device being arranged to permit, from within an area of said optically variable structure, emission of luminescent radiation of said first wavelength from said device at a first predetermined angle of emission, and to permit, from the optically variable structure area, emission of luminescent radiation of said second wavelength from said device at one or both of (1) said first angle of emission and (2) a second predetermined angle of emission, different from said first angle of emission, and said optically variable structure is arranged to cause, from the optically variable structure area, the emissivity of said device for luminescent radiation of said first or second wavelengths to change relative to the emissivity of the device for luminescent radiation of the other of the first or second wavelengths with a change in emission angle of luminescent radiation from said device from said first emission angle to said second emission angle; and wherein the luminescent material comprises a first material which luminesces at said first wavelength and a second material which luminesces at said second wavelength, and said first luminescent material which luminesces at said first wavelength is in the same layer as the second luminescent material which luminesces at the second wavelength or said first luminescent material which luminesces at said first wavelength is in a different layer from the second luminescent material which luminesces at said second wavelength, wherein the luminescent material which luminesces at said first wavelength has a boundary defining a first predetermined shape, wherein the luminescent material which luminesces at said second wavelength has a boundary defining a second predetermined shape, wherein at least one of the form and size of said second predetermined shape is different from that of said first predetermined shape, and wherein said first and second predetermined shapes at least partially overlap one another. - View Dependent Claims (99, 100, 101)
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102. A device comprising:
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a luminescent material having an area, which, when stimulated, luminesces to produce luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different from the first wavelength; and an optically variable structure that receives and through which is transmitted the luminescent radiation of the first and second wavelengths from the luminescent material and that is constructed to control emission from the device of the luminescent radiation of at least one of the first and second wavelengths received from the luminescent material and transmitted through the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted at predetermined angles of emission from the optically variable structure, and wherein the optically variable structure is not the luminescent material; the optically variable structure including an area from within which emission of luminescent radiation of the first and second wavelengths from the device occurs, the optically variable structure being arranged to cause, from the optically variable structure area, the relative emissivity of the device for luminescent radiation of the first and second wavelengths to change with at least one or both of (1) a change in emission angle of luminescent radiation from said device and (2) a change in the direction or angle of incidence of stimulating radiation on said device for stimulating said luminescent material.
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103. A method of authenticating a security device which includes a luminescent material having an area, which, when stimulated, luminesces to produce luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different from the first wavelength, and an optically variable structure that receives and through which is transmitted the luminescent radiation of the first and second wavelengths from the luminescent material and that is constructed to control emission from the device of luminescent radiation of at least one of the first and second wavelengths received from the luminescent material and transmitted through the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted at predetermined angles of emission from the optically variable structure, wherein the optically variable structure is not the luminescent material, the method comprising the steps of:
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exposing said security device to stimulating radiation for stimulating said luminescent material to luminesce and thereby produce luminescent radiation, and observing the colour shift in the luminescent radiation from said security device with at least one of (1) a change in emission angle from said security device and (2) a change in the direction or angle of incident stimulating radiation on said security device. - View Dependent Claims (104)
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105. A method of authenticating a security device which includes a luminescent material having an area, which, when stimulated, luminesces to produce luminescent radiation of first and second wavelengths from the luminescent material area, the second wavelength being different from the first wavelength, and an optically variable structure that receives and through which is transmitted the luminescent radiation of the first and second wavelengths from the luminescent material and that is constructed to control emission from the device of the luminescent radiation of at least one of the first and second wavelengths received from the luminescent material and transmitted through the optically variable structure, such that relative intensities of the luminescent radiation of the first and second wavelengths changes with emission angle, resulting in an angle-dependent colour shift in the luminescent radiation emitted at predetermined angles of emission from the optically variable structure, wherein the optically variable structure is not the luminescent material, the method comprising the steps of:
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exposing the security device to stimulating radiation for stimulating the luminescent material to produce luminescent radiation of the first and second wavelengths, and observing or detecting in the luminescent radiation from the security device a change in intensity of luminescent radiation of the first or second wavelengths relative to the intensity of the luminescent radiation of the other of the first or second wavelengths with at least one or both of (1) a change in emission angle from the security device and (2) a change in direction or angle of incidence of stimulating radiation on the security device for stimulating said luminescent material.
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Specification