Patent EP0275601A1 successfully refreshed from Google Patents.
EP0275601A1
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EP
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Projection device and associated display device
Assignee: Koninklijke Philips NV
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Filing: 1987-12-18
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Granted: —
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Expires: 2007-12-18
Abstract
Abstract Radiation from a radiation source (2) is converted into light of a desired spectral character by causing the radiation from tne source (2) to excite luminescent material (18) which is present between two interference filters (22, 23). In combination with opto-electronic elements monochrome pictures are obtained which are suitable for use in projection television. The sandwich of luminescent material (18) and interference filters (22, 23) may form part of a display device (3), for example an LCD, but it may alternatively be integrated, together with the radiation source, to form a separate illumination source.
Inventors
- 👤 Leendert Vriens
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 02:25
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/133617; H04N3/00; H04N3/10; H04N3/12; H04N3/127; H04N9/3102; H04N9/3105
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
213 words
A projection device comprising a projection screen, at least one radiation source and at least one monochrome display device for operation in the transmission mode, with an electro-optical means between two parallel substrates provided with drive means to cause the electro-optical means to change its transmission state at least locally and to define a pattern in the electro-optical means which is projected via projection means onto the projection screen, characterized in that the display device is provided with a layer of material luminescing in one colour, which material can be excited by radiation from the radiation source and in that a first interference filter is arranged between the radiation source and the layer of luminescent material, which filter substantially completely passes radiation suitable for excitation and substantially completely reflects radiation generated in the luminescent material, whilst a second interference filter is arranged on the other side of the layer of luminescent material, which filter has a high transmission for light of the desired spectral characteristic which is emitted by the luminescent layer at small angles to the normal on the filter and in which the reflection considerably increases for light rays of the said spectral characteristic which extend at an angle of more than 20 to 35° to the normal on the filter.
Claim 2
Dependent Claim
213 words
A projection device comprising a projection screen, at least one radiation source and at least one monochrome display device for operation in the transmission mode, with an electro-optical means between two parallel substrates provided with drive means to cause the electro-optical means to change its transmission state at least locally and to define a pattern in the electro-optical means which is projected via projection means onto the projection screen, characterized in that the display device is provided with a layer of material luminescing in one colour, which material can be excited by radiation from the radiation source and in that a first interference filter is arranged between the radiation source and the layer of luminescent material, which filter substantially completely passes radiation suitable for excitation and substantially completely reflects radiation generated in the luminescent material, whilst a second interference filter is arranged on the other side of the layer of luminescent material, which filter has a high transmission for light of the desired spectral characteristic which is emitted by the luminescent layer at small angles to the normal on the filter and in which the reflection considerably increases for light rays of the said spectral characteristic which extend at an angle of more than 20 to 35° to the normal on the filter.
Claim 3
Dependent Claim
147 words
A projection device as claimed in Claim 1, characterized in that the device comprises three monochrome display devices, each with a ma terial luminescing in a different colour and each with an optical axis extending perpendicularly from the centre of the display portion of the display device, the optical axes of the three display devices being co-planar, the axes of the first and second display devices coinciding and the axis of the third display device constituting the principle axis of the projection device, said axis being perpendicular to the two coincident axes and in that the device also comprises dichroic prisms reflecting the image of the first display device and the image of the second display device in the direction of the principle axis and away from the third display device and passing the image of the third display device in tne direction of the principle axis.
Claim 4
Dependent Claim
171 words
A projection device as claimed in Claim 1, characterized in that the device comprises three monochrome display devices, each with a material luminescing in a different colour and each with an optical axis extending perpendicularly from the centre of the display portion of the display device, the optical axes of the three display devices being co-planar, the axes of the first and second display devices coinciding and the axis of the third display device constituting the principle axis of the projection device, said axis being perpendicular to the two coincident axes and in that the device also comprises two plane dichroic reflecting mirrors intersecting each other and extending perpendicularly to the said plane and through the point of intersection of the axes, each mirror extending at an angle of 45° to the principle axis, the first mirror reflecting the image of the first display device and the second mirror reflecting the image of the second display device in the direction of the principle axis and away from the third display device.
Claim 5
Dependent Claim
55 words
A projection device as claimed in Claim 1, 2 or 3, characterized in that the layer of luminescent material and the two interference filters, viewed in the radiation path, are arranged in front of the electro-optical means and in that the electro-optical means comprises a light switch for the radiation generated in the luminescent material.
Claim 6
Dependent Claim
59 words
A projection device as claimed in any one of the preceding Claims, characterized in that the device comprises at least one illumination source having a wall in which the layer of luminescent material and the two interference filters are present, the other part of the display device being separated from tne illumination source by means of an open space.
Claim 7
Dependent Claim
26 words
A projection device as claimed in Claim 5, characterized in that the outer side of tne wall of the illumination source is provided with a polariser.
Claim 8
Dependent Claim
48 words
A projection device as claimed in Claim 1, 2 or 3, characterized in that the electro-optical means, viewed in the radiation path, is present in front of the layer of luminescent material and the two interference filters and comprises a switch for the radiation exciting the luminescent material.
Claim 9
Dependent Claim
23 words
A projection device as claimed in any one of the preceding Claims, characterized in that the electro-optical means comprises a liquid crystalline material.
Claim 10
Dependent Claim
56 words
A projection device as claimed in any one of the preceding Claims, cnaracterized in that the first interference filter is a dielectric filter comprising at least six layers alternately having a high and a low refractive index, said filter substantially completely passing the exciting radiation and substantially completely reflecting the radiation generated in the luminescent material.
Claim 11
Dependent Claim
63 words
A projection device as claimed in Claim 9, characterized in that the layers having a high refractive index comprise one or more of tne materials hafnium oxide (HfO₂), zirconium oxide (ZrO₂), titanium oxide (TiO₂), tantalum oxide (Ta₂O₅) or niobium oxide (Nb₂O₅) and the layers having a low refractive index comprise one or more of the materials magnesium fluoride (MgF₂) or silicon oxide (SiO₂).
Claim 12
Dependent Claim
36 words
A projection device as claimed in any one of Claims 1 to 8, characterized in that the first interference filter has 3 - 5 layers of alternately a metal layer and a layer of dielectric material.
Claim 13
Dependent Claim
138 words
A projection device as claimed in any one of the preceding Claims, characterized in that the second interference filter comprises a plurality of layers manufactured alternately from a material having a high refractive index and from a material having a low refractive index and is composed of at least nine layers each having an optical thickness n . d ., in which n is the refractive index of the material of the layer and d is the thickness, said optical thickness n . d . being 0.2 λ f and 0.3 λ f in which λ f is equal to p × λ , in which λ is the central wavelength of the relevant display device, in which p is a number between 1.16 and 1.30 and in which the average optical thickness is 0.25 λ f .
Claim 14
Dependent Claim
22 words
A projection device as claimed in Claim 12, characterized in that the second interference filter is composed of 9 to 30 layers.
Claim 15
Dependent Claim
28 words
A projection device as claimed in Claim 13, characterized in that the optical tnickness n . d . is between 0.23 λ f and 0.27 λ f .
Claim 16
Dependent Claim
25 words
A projection device as claimed in any one of the preceding Claims, characterized in that a high-pressure mercury lamp is used as a radiation source.
Claim 17
Dependent Claim
68 words
A projection device as claimed in Claim 15, characterized in that the radiation source emits radiation at a central wavelength of 254 nanometers and the projection device comprises three display devices for the colours red, green and blue, tme luminescent layer of each of the display devices comprising Y₂O₃: Eu as a red phosphor; CeMgAl₁₁O₁₉: Tb as a green phosphor and BaMg₂Al₁₆O₂₇: Eu as a blue phosphor, respectively.
Claim 18
Dependent Claim
25 words
A projection device as claimed in any one of the preceding Claims, characterized in that a common radiation source is used for the display devices.
Claim 19
Dependent Claim
43 words
A projection device as claimed in any one of Claims 1 to 14, characterized in that for each display element the device comprises a radiation source which emits radiation at a sufficiently short wavelength to excite the phosphors in the associated display element.
Claim 20
Dependent Claim
150 words
A display device for use in a projection device as claimed in any one of Claims 1 to 18, comprising electro-optical means between two parallel substrates provided with drive means to cause the electro-optical means to change its state at least locally, characterized in that one of the substrates is provided with a layer of monochrome luminescent material between a first interference filter which substantially completely passes the radiation suitable for excitation of the luminescent material and substantially completely reflects radiation generated in the luminescent material, and a second interference filter having a high transmission for light of the desired spectral characteristic which is emitted by the luminescent layer at small angles to the normal on the filter and in which the reflection considerably increases for light rays of the said spectral characteristic which extend at an angle of more than 20 to 35° to the normal on the filter.
Claim 21
Dependent Claim
19 words
A display device as claimed in Claim 19, characterized in that the electro-optical means comprises a liquid crystalline material.
Claim 22
Dependent Claim
54 words
A display device as is claimed in Claim 13 or 16, characterized in that the first interference filter is a dielectric filter comprising at least 6 layers alternately having a high and a low refractive index, which filter substantially completely passes the exciting radiation and substantially completely reflects radiation generated in the luminescent material.
Claim 23
Dependent Claim
60 words
A projection device as claimed in Claim 21, characterized in that the layers having a high refractive index comprise one or more of the materials hafnium oxide (HfO₂), zirconium oxide (ZrO₂), tantalum oxide (Ta₂O₅) or niobium oxide (Nb₂O₅) and the layers having a low refractive index comprise one or more of the materials magnesium fluoride (MgF₂) or silicon oxide (SiO₂).
Claim 24
Dependent Claim
33 words
A display device as claimed in Claim 19 or 20, characterized in that the first interference filter comprises 3 to 5 layers of alternately a metal layer and a layer of dielectric material.
Claim 25
Dependent Claim
125 words
A display device as claimed in Claim 19 or 20, characterized in that the second interference filter has a plurality of layers which are manufactured alternately from a material having a high refractive index and from a material having a low refractive index and is composed of at least nine layers each having an optical thickness n . d . in which n is the refractive index of the material of the layer and d is the thickness, said optical thickness n . d being between 0.2 λ f and 0.3 λ f in wnich λ f is equal to p × λ , in which λ is the central wavelength of the relevant display device and p is a number between 1.16 and 1.30
Claim 26
Dependent Claim
22 words
A display device as claimed in Claim 24, characterized in that the second interference filter is composed of 14 to 30 layers.
Claim 27
Dependent Claim
28 words
A display device as claimed in Claim 25, characterized in that the optical thickness n . d . is between 0.23 λ f and 0.27 λ f .
Claim 28
Dependent Claim
162 words
An illumination source comprising a space accommodating a radiation source and bounded by at least a flat wall, characterized in that tne wall is provided with at least one layer of a material luminescing in one colour, which can be excited by the radiation source and in that a first interference filter is arranged between the radiation source and the layer of luminescent material, which filter substantially completely passes the radiation suitable for excitation and substantially completely reflects radiation generated in the luminescent material, whilst a second interference filter is arranged on the other side of the layer of luminescent material, which filter has a high transmission for light of the desired spectral characteristic which is emitted by the luminescent layer at small angles to the normal of the filter and in which the reflection considerably increases for light rays of the said spectral characteristic which extend at an angle of more than 20 to 35° to the normal on the filter.
Claim 29
Dependent Claim
162 words
An illumination source comprising a space accommodating a radiation source and bounded by at least a flat wall, characterized in that tne wall is provided with at least one layer of a material luminescing in one colour, which can be excited by the radiation source and in that a first interference filter is arranged between the radiation source and the layer of luminescent material, which filter substantially completely passes the radiation suitable for excitation and substantially completely reflects radiation generated in the luminescent material, whilst a second interference filter is arranged on the other side of the layer of luminescent material, which filter has a high transmission for light of the desired spectral characteristic which is emitted by the luminescent layer at small angles to the normal of the filter and in which the reflection considerably increases for light rays of the said spectral characteristic which extend at an angle of more than 20 to 35° to the normal on the filter.
Claim 30
Dependent Claim
28 words
An illumination source as claimed in Claim 27, characterized in that the second interference filter is provided with a polariser on the side remote from the luminescent layer.
Claim 31
Dependent Claim
54 words
An illumination source as claimed in Claim 27 or 28, characterized in that the first interference filter is a dielectric filter comprising at least six layers alternately having a high and a low refractive index, which filter substantially completely passes the exciting radiation and substantially completely reflects the radiation generated in the luminescent material.
Claim 32
Dependent Claim
63 words
An illumination source as claimed in Claim 29, characterized in that the layers having a high refractive index comprise one or more of the materials hafnium oxide (HfO₂), zirconium oxide (ZrO₂), titanium oxide (TiO₂), tantalum oxide (Ta₂O₅) or niobium oxide (Nb₂O₅) and the layers having a low refractive index comprise one or more of the materials magnesium fluoride (MgF₂) or silicon oxide (SiO₂).
Claim 33
Dependent Claim
33 words
An illumination source as claimed in Claim 27 to 29 characterized in that first interference filter comprises 3 to 5 layers of alternately a metal layer and a layer of a dielectric material.
Claim 34
Dependent Claim
117 words
An illumination source as claimed in any one of Claims 27 to 31 characterized in that the second interference filter comprises a plurality of layers which are manufactured alternately from a material having a high refractive index and from a material having a low refractive index and are composed of at least nine layers each having an optical thickness n . d . of between 0.2 λ f and 0.3 λ f in which λ f is equal to p × λ , in which λ is the central wavelength of the relevant display device, in which p is a number between 1.16 and 1.30 and in which the average optical tnickness is 0.25 λ f .
Claim 35
Dependent Claim
22 words
An illumination source as claimed in Claim 32, characterized in that the second interference filter is composed of 9 to 30 layers.
Claim 36
Dependent Claim
31 words
An illumination source as claimed in Claim 33, characterized in that the optical thickness n . d . of the layers is between 0.23 λ f and 0.27 λ f .
Claim 37
Dependent Claim
26 words
An illumination source as claimed in any one of Claims 27 to 33, cnaracterized in that a high-pressure mercury lamp is used as a radiation source.
Claim 38
Dependent Claim
32 words
An illumination source as claimed in Claim 35, characterized in that one or more of the materials ZnS: Ag (blue); (Zn,Cd)S: Cu,Ag (green) and Y₂O₂S: Eu (red) is chosen as a phosphor.
Claim 39
Dependent Claim
28 words
An illumination source as claimed in any one of Claims 27 to 33, characterized in that the radiation source emits radiation at a central wavelength of 254 nanometers.
Claim 40
Dependent Claim
31 words
An illumination source as claimed in Claim 37, characterized in that one or more of the materials Y₂O₃:Eu (red); CeMgAl₁₁O₁₉: Tb (green) and BaMg₂Al₁₆O₂₇: Eu (blue) is chosen as a phosphor.
References Cited (Backward Citations)
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