WO2023247835A1

WO2023247835A1 - Phosphor screen, imaging device, and method

Info

Publication number: WO2023247835A1
Application number: PCT/FI2023/050378
Authority: WO
Inventors: Alexey GANZHINOV; Mika SIRKIÄ; Jani Holopainen
Original assignee: Lumineq Oy
Priority date: 2022-06-23
Filing date: 2023-06-21
Publication date: 2023-12-28

Abstract

A phosphor screen (1000), and imaging device, and a method for fabricating a phosphor screen are disclosed. The phosphor screen (1000) comprises a transparent substrate (1100), a scintillator layer (1200) supported by the substrate (1100), and a transparent display element (1300) supported by the substrate (1100) and comprising a first conductor layer (1310), a second conductor layer (1320), and an emissive layer (1330) configured to emit light in consequence of electrical voltage coupled over the emissive layer (1330) between the first conductor layer (1310) and the second conductor layer (1320).

Description

PHOSPHOR SCREEN, IMAGING DEVICE , AND METHOD

FIELD OF TECHNOLOGY

This disclosure concerns imaging technology . In particular, this disclosure concerns phosphor screens , imaging devices comprising phosphor screens , and methods for fabricating phosphor screens .

BACKGROUND

Phosphor screens are commonly used in various fields of technology for visual detection of electrons , protons , heavy ions , ioni zing electromagnetic radiation, and the like . Phosphor screens are also used in conj unction with photocathodes to enable the visuali zation of non-ioni zing non-visible electromagnetic radiation .

For example , in an infrared ( IR) viewer, an IR image incident onto a photocathode generates a photoelectron image to be accelerated towards a phosphor screen by an electrostatic lens , and the phosphor screen is used to convert the photoelectron image into a visible image corresponding to the original IR image . Although imaging devices comprising phosphor screens have been available on the market for decades , their construction may commonly be relatively complicated, consisting of a multitude of functional elements the relative positioning of which requires meticulous attention to detail in designing suitable housings for the elements . The relatively high number of different elements used in such imaging devices also increases their si ze . In light of the above , it may be desirable to develop new solutions related to phosphor screens and imaging devices .

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description . This summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter .

According to a first aspect , a phosphor screen is provided . The phosphor screen comprises a transparent substrate and a scintillator layer supported by the substrate . The phosphor screen further comprises a transparent display element comprising a first conductor layer, a second conductor layer, and an emis sive layer configured to emit light in consequence of electrical voltage coupled over the emiss ive layer between the first conductor layer and the second conductor layer, the display element supported by the substrate .

According to a second aspect, imaging device comprising a phosphor screen in accordance with the first aspect is provided .

According to a third aspect , a method for fabricating a phosphor screen is provided . The method comprises providing a transparent substrate ; forming a transparent display element supported by the substrate , the process of forming a transparent display element comprising forming a first conductor layer, forming an emissive layer, and forming a second conductor layer such that the emissive layer is arranged between the first conductor layer and the second conductor layer ; and forming a scintillator layer supported by the substrate .

It is specifically to be understood that the method according to the third aspect may be used to provide a phosphor screen according to the first aspect and any number of embodiments described in relation to the first aspect .

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be better understood from the following detailed description read in light of the accompanying drawings , wherein :

FIG . 1 shows a phosphor screen,

FIG . 2 depicts another phosphor screen,

FIG . 3 shows an imaging device , and

FIG . 4 illustrates a method for fabricating a phosphor screen .

Unless specifically stated to the contrary, any drawing of the aforementioned drawings may be not drawn to scale such that any element in said drawing may be drawn with inaccurate proportions with respect to other elements in said drawing in order to emphasi ze certain structural aspects of the embodiment of said drawing .

Moreover, corresponding elements in the embodiments of any two drawings of the aforementioned drawings may be disproportionate to each other in said two drawings in order to emphasi ze certain structural aspects of the embodiments of said two drawings . In the drawings, corresponding elements are referred to using the same reference numbers.

DETAILED DESCRIPTION

FIG. 1 shows a schematic partial cross-sectional view of a phosphor screen 1000 according to an embodiment.

Throughout this disclosure, a "phosphor screen" may refer to a flat and/or smooth panel-like element configured to emit photons in response to impinging ionizing radiation. Herein, "ionizing radiation" may refer to radiation with sufficient particle or photon energy to induce ionization in a medium. Ionizing radiation may comprise radiation with particle or photon energies of at least 3.89 electron volts (eV) , at least 10 eV, or at least 33 eV, for example.

In the embodiment of FIG. 1, the phosphor screen 1000 comprises a transparent substrate 1100.

In this specification, a "substrate" may refer to a solid body providing a surface such that material may be arranged, deposited, etched, and/or inscribed on the surface. A substrate may be formed, for example, of glass, e.g., soda-lime, aluminosilicate, and/or any other appropriate transparent glass, or plastic. Suitable plastic materials include, for example, polyethylene (PE) , polycarbonate (PC) , and mixtures thereof, without being limited to these examples.

Throughout this specification, an element or material being "transparent", may refer to a quality, i.e., "transparency", of said element or material of allowing light of wavelength ( s ) within a range of relevant wavelengths to propagate through such element or material. Said range of relevant wavelengths may generally depend on intended usage of such transparent element or material. For example, in some embodiments, a range of relevant wavelengths may correspond to at least part of the visible wavelength spectrum and/or extend from one of 350 nm, 360 nm, 370 nm, ..., 730 nm, 740 nm, and 750 nm to any other of said wavelengths. Transparency of an element may refer to a capability of said element to transmit a main portion of irradiance within a range of relevant wavelengths incident on said element along an initial incidence direction. A transparent element with a layer structure may transmit, for example, 50 % or more, or 60 % or more, or 70 % or more or 80 % or more, or 90 % or more of irradiant energy incident onto it at a range of relevant wavelengths.

The substrate 1100 may be formed of soda-lime glass and have a thickness of approximately 0.7 millimeters (mm) . In other embodiments, any suitable substrates formed of any suitable materials, such as soda-lime glass, fused silica, quartz, and/or one or more transparent plastics, and having any suitable thicknesses, for example, thicknesses greater than or equal to 0.1 mm, or to 0.2 mm and/or less than or equal to 2 mm or to 1.5 mm, or to 1.1 mm, may be used.

Herein, an element being "formed of" a material or materials may refer to said element comprising, or comprising substantially, or consisting essentially of, or consisting of said material or materials.

In the embodiment of FIG. 1, phosphor screen 1000 also comprises a scintillator layer 1200 supported by the substrate 1100. In this disclosure , a " layer" may refer to a generally sheet-formed element arranged on a surface or a body . Additionally or alternatively, a layer may refer to one of a series of superimposed, overlaid, or stacked generally sheet-formed elements . A layer may be path-connected . Some layers may be locally path-connected and disconnected .

In this specification , a "scintil lator" may refer to a material that emits l ight when excited by ioni zing radiation . Although a layer may generally comprise a plurality of sublayers of different materials or material compositions , an "scintillator layer" may refer to a layer formed of scintillator material ( s ) .

The phosphor screen 1000 of the embodiment of FIG . 1 further comprises a transparent display element 1300 supported by the substrate 1100 .

Throughout this specification, a "display element" may refer to an element comprising at least one emissive area for emitting light therefrom in order to present visual information .

The display element 1300 of the embodiment of FIG . 1 comprises a first conductor layer 1310 , a second conductor layer 1320 , and an emissive layer 1330 configured to emit light in consequence of electrical voltage coupled over the emissive layer 1330 between the first conductor layer 1310 and the second conductor layer 1320 .

Throughout this specification, a "conductor" may refer to an electrical conductor material and/or the electrical conductivity thereof . Consequently, a "conductor layer" may refer to a layer compris ing a conductor material . Additionally or alternatively, a conductor layer may be electrically non-insulating, e.g., electrically conductive. Typically, a conductor layer may comprise, for example, indium tin oxide (ITO) , aluminum-doped zinc oxide (AZO, ZnO:Al) , any other appropriate transparent conductive oxide (TOO) , and/or any other transparent conductor material. Additionally or alternatively, a conductor layer may comprise, for example, a thin metal mesh. Such layers, with sufficiently low thicknesses, may be transparent.

In this disclosure, an "emissive layer" may refer to a layer formed of material (s) exhibiting luminescence, e.g., electroluminescence.

Generally, a phosphor screen comprising both a scintillator layer and a transparent display element supported by the same substrate may enable overlaying additional visual information onto images produced by an imaging device comprising such a phosphor screen. Additionally or alternatively, a phosphor screen comprising both a scintillator layer and a transparent display element supported by the same substrate may facilitate reducing the number of separate elements in an imaging device comprising such a phosphor screen.

Each of the first conductor layer 1310 and the second conductor layer 1320 of the embodiment of FIG. 1 may be formed of ITO and AZO and have a thickness of approximately 150 nanometers (nm) . In other embodiments, first conductor layers and second conductor layers may be formed of any suitable material (s) , for example, one or more TCOs, such as ITO and/or AZO, and have any suitable thicknesses, for example, thicknesses greater than or equal to 70 nm, or to 90 nm, or to 100 nm and/or less than or equal to 400 nm, or to 300 nm, or to 200 nm .

Although not shown in FIG . 1 , the first conductor layer 1310 and/or the second conductor layer 1320 may be implemented as patterned conductor layers .

Herein, a "patterned" layer may refer to a layer extending non-unif ormly throughout an extent thereof . Additionally of alternatively, a patterned layer may refer to a structure comprising one or more discontinuities . Additionally or alternatively, a patterned layer may be locally path-connected and disconnected . Additionally or alternatively, a patterned layer may comprise a hole in a topological (homeomorphism) sense .

Such patterned nature of a layer may be implemented by several patterns , the patterns being separated from each other . In some embodiments , a patterned layer may be implemented with j ust one pattern . Then, the "patterned" nature of said layer may be implemented with the pattern not covering an underlying surface entirely, i . e . , at least one opening or region exists in an area of said underlying surface which i s not covered by said layer . Naturally, a "patterned conductor layer" may refer to a conductor layer with corresponding features .

Any appropriate patterning processes may generally be used to pattern a patterned conductor layer . Such patterning process may comprise several stages , such as cleaning, drying, photoresist coating, pre-baking, exposure , developing, etching, and/or stripping with cleaning/drying steps . For example , lithographic patterning for ITO as the material of a conductor layer may be carried out with an automated photolithography in- line tool utili zing wet-chemical processes . A selected etchant , which may be , for example , a mixture of hydrochloric acid (HC1 ) and nitric acid (HNO3 ) , removes the desired areas of the conductor layer .

The display element 1300 of the embodiment of FIG . 1 may be implemented as a segment-type display element . In other embodiments , a display element may be implemented in any suitable manner , for example , as a segment-type display element or as a matrix-type display element .

In this disclosure , a "segment-type" display element may refer to a display element in which emissive areas form individually or group-by-group controllable segments of letters , numbers , and/or other distinctive symbols . On the other hand, a "matrix-type" display element may refer to a display element in which conductor patterns of two patterned conductor layers define emissive parts of an emissive layer at locations where said conductor patterns overlap . Such emissive parts of a matrix-type display element may have , for example , rectangular or square shapes . In a matrix-type display, at least one conductor pattern may be involved in defining a plurality of emissive parts .

In the embodiment of FIG . 1 , both the display element 1300 and the scintillator layer 1200 are arranged towards a first transverse direction 1001 from the substrate 1100 . Generally, a display element and a scintillator layer of a phosphor screen being arranged towards a first transverse direction from a substrate may facilitate fabricating the phosphor screen . In other embodiments , a display element and a scintillator layer may be arranged in any suitable positions with respect to substrate . For example , is some embodiments , a display element and the scintil lator layer may be arranged towards a first transverse direction from a substrate . In some embodiments , a display element may be arranged towards a first transverse direction from a substrate , and a scintillator layer may be arranged towards a second transverse direction opposite to the first transverse direction from the substrate .

The scintillator layer 1200 of the embodiment of FIG . 1 is arranged towards the first transverse direction 1001 from the display element 1300 . In other embodiments , wherein a display element and a scintillator layer are arranged towards a first transverse direction from a substrate , the scintillator layer may or may not be arranged towards the first transverse direction from the display element . Generally, when a display element and a scintillator layer are arranged towards a first transverse direction from a substrate , the scintillator layer being arranged towards the first transverse direction from the display element may shield the display element from radiation, for example , ioni zing radiation, incident onto a phosphor screen, which may, in turn, increase a li fetime of the phosphor screen, and/or enable avoiding image artefacts caused by the scintillator layer in images produced by the display element .

In the embodiment of FIG . 1 , the phosphor screen 1000 comprises a conductor coating 1400 arranged such that the scintillator layer 1200 is situated between the conductor coating 1400 and the substrate 1100 . Generally, a phosphor screen comprising a conductor coating arranged such that a scintillator layer is situated between the conductor coating and a substrate may enable accelerating charged particles towards the scintillator layer and/or increase reflectance of light emitted by scintillator layer towards the substrate , which may, in turn, increase brightness of an imaging device comprising the phosphor screen . In other embodiments , a phosphor screen may or may not comprise a conductor coating arranged such that a scintillator layer is situated between the conductor coating and a substrate . For example , in some embodiments , a phosphor screen may comprise a transparent intermediate conductor layer arranged between a scintillator layer and a substrate in addition to or as an alternative to such a conductor coating .

The display element 1300 of the embodiment of FIG . 1 comprises a first dielectric layer 1341 between the first conductor layer 1310 and the emissive layer 1330 and a second dielectric layer 1342 between the second conductor layer 1320 and the emissive layer 1330 , and the emissive layer 1330 of the embodiment of FIG . 1 comprises an electroluminescent phosphor material . In other embodiments , a display element may or may not comprise a first dielectric layer between a first conductor layer and an emissive layer and a second dielectric layer between a second conductor layer and the emiss ive layer and the emissive layer may or may not comprise an electroluminescent phosphor material . For example , in some embodiments , a display element may be implemented as an organic light-emitting diode (OLED) display element , wherein an emissive layer comprises an organic compound configured to emit light in response to an electric current passing between a first conductor layer and a second conductor layer via the emissive layer . In this specification, a "dielectric layer" may refer to a layer formed of electrical insulator material (s) . Additionally or alternatively, a dielectric layer may refer to layer exhibiting an average electrical resistivity of at least 10⁵ ohm-meters (Qm) , or at least 10⁶ Qm, or at least 10⁷ Qm, or at least 10⁸ Qm, for example, at standard temperature and pressure conditions.

Each of the first dielectric layer 1341 and the second dielectric layer 1342 of the embodiment of FIG. 1 may be formed of a mixed oxide of aluminum (Al) and titanium (Ti) and have a thickness of approximately 200 nm. In other embodiments, first dielectric layers and second dielectric layers may be formed of any suitable material (s) , for example, aluminum oxide (AI2O3) ; tantalum pentoxide (I^Os) ; titanium dioxide (HO2) ; zirconium dioxide (ZrCy) ; hafnium dioxide (HfCy) ; and mixtures and laminates, e.g., nanolaminates, thereof, and have any suitable thicknesses, for example, thicknesses greater than or equal to 30 nm, or to 40 nm, or to 50 nm and/or less than or equal to 500 nm, or to 400 nm, or to 300 nm.

In the embodiment of FIG. 1, the display element 1300 comprises a single emissive layer 1330. In other embodiments, a display element may comprise any suitable number of emissive layers, for example, one or more, two or more, or three or more emissive layers. For example, in some embodiments, a display element may comprise a first dielectric layer between a first conductor layer and an emissive layer, a second dielectric layer between a second conductor layer and the emissive layer, a second emissive layer between the second conductor layer and the second dielectric layer, and a third dielectric layer between the second emissive layer and the second conductor layer.

In the embodiment of FIG. 1, the emissive layer 1330 may comprise an electroluminescent phosphor material and the scintillator layer 1200 may comprise a scintillator material different to the electroluminescent phosphor material. Generally, an electroluminescent phosphor material of an emissive layer being different to a scintillator material of a scintillator layer may facilitate discerning light emitted by the emissive layer from light emitted by the scintillator layer. In other embodiments, an electroluminescent phosphor material of an emissive layer may or may not be different to a scintillator material of a scintillator layer.

In the embodiment of FIG. 1, the electroluminescent phosphor material may comprise manganese-doped zinc sulfide (ZnS:Mn) emitting light having a first peak emission wavelength in a yellow-orange wavelength range extending approximately from 565 nm to 625 nm. Generally, utilization of an electroluminescent phosphor material comprising one or more inorganic electroluminescent phosphor materials may increase a lifetime of a phosphor screen. In other embodiments, an electroluminescent phosphor material of an emissive layer may or may not consist of, or consist substantially of, or comprise one or more inorganic electroluminescent phosphor materials, such as one or more metal-doped zinc sulfides, e.g., manganese-doped zinc sulfide (ZnS:Mn) , copper- doped zinc sulfide (ZnS:Cu) , terbium-doped zinc sulfide (ZnS:Tb) , europium-doped zinc-sulfide (ZnS:Eu) , and/or silver-doped zinc sulfide (ZnS:Ag) . The emissive layer 1330 of the embodiment of FIG. 1 may have a thickness of approximately 500 nm. In other embodiments, an emissive layer may have any suitable thickness, for example, a thickness greater than or equal to 50 nm, or to 100 nm, or to 150 nm and/or less than or equal to 1200 nm, or to 1000 nm, or to 900 nm.

In the embodiment of FIG. 1, the scintillator layer 1200 may comprise aluminum and copper co-doped zinc sulfide (ZnS:Cu,Al) as scintillator material. ZnS:Cu,Al is a cathodoluminescent material that emits light having a second peak emission wavelength in a green wavelength range extending approximately from 495 nm to 570 nm in response to impacting electrons. In other embodiments, a scintillator layer may comprise any suitable scintillator material (s) . In some embodiments, a scintillator layer may or may not consist of, consist substantially of, or comprise one or more cathodoluminescent scintillator materials. In some embodiments, a scintillator layer may consist of, consist substantially, or comprise in addition to or as an alternative to cathodoluminescent scintillator material (s) one or more non-cathodoluminescent scintillator materials. Generally, a scintillator layer consisting of, consisting substantially of, or comprising one or more cathodoluminescent scintillator materials may enable utilization of a phosphor screen in conjunction with a photocathode or an electron gun.

In some embodiments, a scintillator layer may consist of, consist substantially of, or comprise one or more inorganic cathodoluminescent materials, e.g., manga- nese-doped zinc silicate ( Zn2SiO4 : Mn) , calcium tung- state (C W04) , silver-doped zinc sulfide (ZnS:Ag) , man- ganese-doped potassium magnesium fluoride (KMgFs Mn) , aluminum and copper co-doped zinc sulfide (ZnS:Cu,Al) , europium-doped yttrium oxide sulfide (Y2O2S:Eu) , manganese and lead co-doped calcium metasilicate (Ca- SiO3:Mn,Pb) , copper-doped zinc sulfide (ZnS:Cu) , manga- nese-doped magnesium fluoride (MgF2:Mn) , manganese and arsenide co-doped zinc silicate ( Z^SiCg : Mn, As ) , manganese and indium co-doped zinc silicate ( Z^SiCg : Mn, In) , terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) , ter- bium-doped lanthanum oxysulfide (La22O2S : Tb) , terbium- doped yttrium oxide sulfide (Y2O2S:Tb) , terbium and europium co-doped yttrium oxide sulfide ( Y2O2S : Tb, Eu) , ce- rium-doped yttrium aluminum garnet (Y3AI5O12 : Ce) , ce- rium-doped yttrium orthosilicate (Y2SiOs:Ce) , and/or europium-doped yttrium oxide (Y2Os:Eu) . Generally, utilization of cathodoluminescent scintillator materials comprising one or more inorganic cathodoluminescent materials may increase a lifetime of a phosphor screen under electron bombardment.

The display element 1300 of the embodiment of FIG. 1 is implemented specifically as an inorganic thin film electroluminescent (TFEL) display element. In other embodiments, display element may be implemented as any suitable type of display element, for example, as a thin film display element, e.g., an inorganic TFEL display element .

Throughout this specification, a "thin film" display element may refer to a display element having a total thickness less than or equal to 50 micrometers (pm) , or less than or equal to 20 pm, or less than or equal to 10 pm. Individual layers of a thin film display element may have thicknesses , for example , in a range from a few nanometers to some hundreds of nanometers or some micrometers .

Further, an "inorganic thin film electroluminescent" display element may refer to a thin film display element that comprises an emissive layer formed of inorganic electroluminescent phosphor material ( s ) . Additionally or alternatively, an inorganic thin film electroluminescent display element may refer to a thin film display element , wherein a first dielectric layer may be arranged between an emis sive layer and a first conductor layer and a second dielectric layer may be arranged between said emissive layer and a second conductor layer . In inorganic TFEL displays , an alternating or pulsed driving voltage may be appl ied over a first dielectric layer, an emissive layer, and a second dielectric layer, for example , between at least part of a first conductor layer and at least part of a second conductor layer . An inorganic TFEL display driven with pulsed or alternating voltages may be referred to as an inorganic "AC TFEL display" . Peak-to-peak amplitudes of such driving voltages may be , for example , few hundreds of volts , generated by a specific display driver unit and fed to display electrodes via conductors from dis play terminals of said display driver unit .

FIG . 2 depicts a schematic partial cross-sectional view of a phosphor screen 2000 according to an embodiment . Unless specified otherwise , the embodiment of FIG . 2 may be in accordance with any of the embodiments disclosed with reference to and/or in conj unction with FIG . 1 . Additionally or alternatively, although not explicitly shown in FIG . 2 , the embodiment of FIG . 2 or any part thereof may generally comprise any features and/or elements of the embodiment of FIG . 1 that are omitted from FIG . 2 .

Similarly to the embodiment of FIG . 1 , the phosphor screen 2000 of the embodiment of FIG . 2 comprises a transparent substrate 1100 and a scintillator layer 1200 supported by the substrate 1100 .

In the embodiment of FIG . 2 , the phosphor screen 2000 further comprises a transparent display element 2300 comprising a first conductor layer 2310 , a second conductor layer 2320 , and an emissive layer 2330 configured to emit light in consequence of electrical voltage coupled over the emissive layer 2330 between the first conductor layer 2310 and the second conductor layer 2320 , and the display element 2300 is supported by the substrate 1100 .

The scintillator layer 1200 of the embodiment of FIG . 2 is arranged towards a first transverse direction 1001 from the substrate 1100 , and the display element 2300 is arranged towards a second transverse direction 2002 opposite to the first transverse direction 1001 from the substrate 1100 . Generally, a scintillator layer being arranged towards a first transverse direction from a substrate and a display element being arranged towards a second transverse direction opposite to the first transverse direction from the substrate may facilitate shielding the display element from ioni zing radiation during operation of a phosphor screen, which may, in turn, increase lifetime of the phosphor screen . In other embodiments , wherein a scintillator layer is arranged towards a first transverse direction from a substrate , a display element may or may not be arranged towards a second transverse direction opposite to the first transverse direction from the substrate .

In the embodiment of FIG . 2 , the phosphor screen 2000 comprises a transparent intermediate conductor layer 2400 arranged between the scintillator layer 1200 and the substrate 1100 . Generally, a phosphor screen comprising a transparent intermediate conductor layer arranged between a scintillator layer and a substrate may enable accelerating charged particles towards the scintillator layer and/or reduce unnecessary shielding of the scintillator layer during operation of a phosphor screen, which may, in turn, increase sensitivity of the phosphor screen . In other embodiments , a phosphor screen may or may not comprise a transparent intermediate conductor layer arranged between a scintillator layer and a substrate in addition to or as an alternative to a conductor coating arranged such that the scintillator layer is situated between the conductor coating and the substrate .

The emis sive layer 2330 of the embodiment of FIG . 2 is implemented as OLED layer and may compri se a f luorene- based electroluminescent copolymer, for example , a flu- orene-carbazole copolymer . As such, the emissive layer 2330 comprises an organic electroluminescent material . In other embodiments , an emis sive layer may or may not be implemented as an OLED layer and/or comprise one or more organic electroluminescent materials .

In the embodiment of FIG . 2 , the display element 2300 further comprises a hole transport layer 2340 between the first conductor layer 2310 and the second conductor layer 2320 . The hole transport layer 2340 may comprise a hole transport material , for example , polyvinylcarbazole ( PVK) . In other embodiments , wherein an emissive layer is implemented as an OLED layer, a display element may or may not comprise a hole transport layer between first conductor layer and a second conductor layer .

An emissive layer of an OLED display element may generally comprise organic light-emitting molecules and/or polymers . Additionally, an OLED display element may comprise a number of auxil iary layers between such an emissive layer and a patterned conductor layer in order to improve an efficiency of said display element . Such auxiliary layers may include electron/hole blocking, elec- tron/hole transport , and/or electron/hole inj ection layers .

It is to be understood that the embodiments of the first aspect described above may be used in combination with each other . Several of the embodiments may be combined together to form a further embodiment .

Above , mainly features of phosphor screens are discussed . In the following, more emphasis will lie on aspects related to imaging devices and methods for fabricating phosphor screens . What is said above about the ways of implementation, definitions , details , and advantages related to phosphor screens applies , mutatis mutandis , to the aspects discussed below . The same applies vice versa .

FIG . 3 depicts an imaging device 3000 according to an embodiment , the imaging device 3000 comprising a phosphor screen 3130 in accordance with the first aspect . The phosphor screen 3130 of the embodiment of FIG. 3 may be in accordance with any of the embodiments disclosed with reference to and/or in conjunction with any of FIGs. 1 and 2. Additionally or alternatively, although not explicitly shown in FIG. 3, the embodiment of FIG. 3 or any part thereof may generally comprise any features and/or elements of any of the embodiments of FIGs. 1 and 2 which are omitted from FIG. 3.

In the embodiment of FIG. 3, the imaging device 3000 is implemented as an infrared viewer. In other embodiments, an imaging device may or may not be implemented as an infrared viewer. For example, in some embodiments, imaging device may be implemented as an image intensifier, a transmission electron microscope (TEM) , a reflection high-energy electron diffraction (RHEED) system, a night-vision device (NVD) , an x-ray imaging device, or a scanning electron microscope (SEM) provided with an electron backscatter diffraction (EBSD) device.

In addition to the phosphor screen 3130, the imaging device 3000 of the embodiment of FIG. 3 comprises a photocathode 3110 and an electrostatic lens 3120. In other embodiments, an imaging device may or may not comprise a photocathode and/or an electrostatic lens.

In the embodiment of FIG. 3, the imaging device 3000 comprises a housing 3200 into which the phosphor screen 3130, the photocathode 3110 and the electrostatic lens 3120 are arranged; an objective 3300; and an eyepiece 3400. In other embodiments, an imaging device may or may not comprise one or more of such ele- ments . During operation of the imaging device 3000 of the embodiment of FIG . 3 , the obj ective 3300 gathers infrared radiation and directs it to the photocathode 3110 . The photocathode 3110 produces photoelectrons in consequence of absorbing infrared photons of the infrared radiation directed to it . Then, the photoelectrons are accelerated from the photocathode 3110 towards the phosphor screen 3130 by applying a focusing voltage (V_x ) between the electrostatic lens 3120 and the photocathode 3110 . The photoelectrons are then directed to the phosphor screen 3130 using an acceleration voltage (V₂ ) applied between a conductor coating 3134 of the phosphor screen 3130 and the electrostatic lens 3120 . Then, the photoelectrons impinging onto a scintillator layer 3132 of the phosphor screen 3130 form a first image , while a display element 3133 of the phosphor screen 3130 may be used to form a second image superimposed on the first image . Finally, light emitted by the scintillator layer 3132 and the display element 3133 is directed via the eyepiece 3400 to a user .

Above , mainly features of phosphor screens and imaging devices are discussed . In the following, more emphasis will lie on aspects related to methods for fabricating phosphor screens . What is said above about the ways of implementation, definitions , details , and advantages related to phosphor screens applies , mutatis mutandis , to the method aspect discussed below . The same applies vice versa .

FIG . 4 illustrates a method 4000 for fabricating a phosphor screen . In other embodiments , a method for fabricating a phosphor screen may be identical , similar, or different to the method 4000 of the embodiment of FIG . 4 . In general , a method for fabricating a phosphor screen may comprise any number of additional processes or steps that are not disclosed herein in connection to the method 4000 of the embodiment of FIG . 4 .

In the embodiment of FIG . 4 , the method 4000 comprises providing a transparent substrate 4100 , forming a transparent display element 4200 supported by the substrate , and forming a scintillator layer 4300 supported by the substrate . The process of forming a transparent display element 4200 comprises forming a first conductor layer 4210 , forming an emissive layer 4220 , and forming a second conductor layer 4230 such that the emissive layer is arranged between the first conductor layer and the second conductor layer .

In this specification, a "process" may refer to a series of one or more steps , leading to an outcome . As such, a process may be a single-step or a multi-step process . Additionally, a process may be divisible to a plurality of sub-processes , wherein individual sub-processes of such plurality of sub-processes may or may not share common steps .

Herein, a "step" may refer to a measure taken in order to achieve a pre-defined result . For example , an "atomic layer deposition step" may refer to a step of a process , whereby a layer is formed by atomic layer deposition .

Further, "atomic layer deposition" , or "ALD" , or "atomic layer epitaxy" , may refer to a thin film deposition technology enabling accurate and well-controlled production of thin film coatings with nanoscale thicknesses . During an atomic layer deposition step , a sub- strate may be alternately exposed to at least two precursors , commonly one precursor at a time , to form a coating layer on the substrate by alternately repeating essentially self-limiting surface reactions between the surface of either the substrate or, at later stages of the atomic layer deposition step, the surface of the already formed coating layer and the precursors . As a result , the deposited material is grown on the substrate molecule layer by molecule layer .

As indicated in FIG . 4 using dashed lines , the processes of forming a first conductor layer 4210 , forming an emissive layer 4220 , and forming a second conductor layer 4230 of the embodiment of FIG . 4 may comprise atomic layer deposition 4211 , 4221 , 4231 steps . Generally, one or more , for example , each, of processes of forming a first conductor layer, forming an emissive layer, and forming a second conductor layer comprising an atomic layer deposition step may facilitate forming a phosphor screen with higher degree of feature thickness control , which may, in turn, increase brightness uniformity of fabricated phosphor screens . In other embodiments , one or more of proces ses of forming a first conductor layer, forming an emiss ive layer, and forming a second conductor layer may or may not comprise an atomic layer deposition step . For example , in some embodiments , one or more of proces ses of forming a first conductor layer, forming a second conductor layer, and forming an emissive layer may comprise a sputtering step, an evaporation step, a spin coating step, a Langmuir-Blodgett deposition step, a doctor blade coating step, an inkj et deposition step, a screen printing step, and/or a spray depos ition step in addition to or as an alternative to an atomic layer deposition step .

As again indicated in FIG . 4 using dashed lines , the process of forming a scintillator layer 4300 may comprise a scintillator adhesion 4301 step, whereby a ready-made scintillator element is adhered, for example , using an adhesive to a substrate or a display element , such that it is supported by the substrate . In other embodiments , a method for fabricating a phosphor screen may compri se forming a scintil lator layer in any suitable manner .

Generally, steps of a method for fabricating a phosphor screen implementing processes corresponding to any of the processes of the method 4000 of the embodiment of FIG . 4 need not be executed in a single , fixed order . However, steps implementing a process of providing a transparent substrate are typically executed prior to steps implementing processes of forming a transparent display element and forming a scintillator layer . Moreover, steps implementing a process of forming a first conductor layer and commonly executed forming an emissive layer forming a second conductor layer

It is obvious to a person ski lled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways . The invention and its embodiments are thus not limited to the examples described above , instead they may vary within the scope of the claims .

It wi ll be understood that any benef its and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.

The term "comprising" is used in this specification to mean including the feature (s) or act(s) followed thereafter, without excluding the presence of one or more additional features or acts. It will further be understood that reference to 'an' item refers to one or more of those items.

REFERENCE SIGNS

V_x focusing voltage

V₂ acceleration voltage

1000 phosphor screen 3131 substrate

1001 first transverse di3132 scintillator layer rection 3133 display element

1100 substrate 3134 conductor coating

1200 scintillator layer 3200 housing

1300 display element 3300 obj ective

1310 first conductor layer 3400 eyepiece

1320 second conductor layer 4000 method

1330 emissive layer 4100 providing a transpar¬

1341 first dielectric layer ent substrate

1342 second dielectric 4200 forming a transparent layer display element

1400 conductor coating 4210 forming a first con¬

2000 phosphor screen ductor layer

2002 second transverse di4211 atomic layer deposirection tion

2300 display element 4220 forming an emissive

2310 first conductor layer layer

2320 second conductor layer 4221 atomic layer deposi¬

2330 emissive layer tion

2340 hole transport layer 4230 forming a second con¬

2400 intermediate conductor ductor layer layer 4231 atomic layer deposi¬

3000 imaging device tion

3110 photocathode 4300 forming a scintillator

3120 electrostatic lens layer

3130 phosphor screen 4301 scintillator adhesion

Claims

1. A phosphor screen (1000) comprising:

- a transparent substrate (1100) and

- a scintillator layer (1200) supported by the substrate (1100) , wherein the phosphor screen (1000) further comprises a transparent display element (1300) comprising a first conductor layer (1310) , a second conductor layer (1320) , and an emissive layer (1330) configured to emit light in consequence of electrical voltage coupled over the emissive layer (1330) between the first conductor layer (1310) and the second conductor layer (1320) , the display element (1300) supported by the substrate (1100) .

2. A phosphor screen (1000) according to claim 1, wherein the display element (1300) and the scintillator layer (1200) are arranged towards a first transverse direction (1001) from the substrate (1100) .

3. A phosphor screen (2000) according to claim 1, wherein the scintillator layer (1200) is arranged towards a first transverse direction (1001) from the substrate (1100) , and the display element (2300) is arranged towards a second transverse direction (2002) opposite to the first transverse direction (1001) from the substrate (1100) .

4. A phosphor screen (1000) according to any of the preceding claims, wherein the phosphor screen (1000) comprises a conductor coating (1400) arranged such that the scintillator layer (1200) is situated between the conductor coating (1400) and the sub- strate (1100) and/or a transparent intermediate conductor layer (2400) arranged between the scintillator layer (1200) and the substrate (1100) .

5. A phosphor screen (1000) according to any of the preceding claims, wherein the display element (1300) comprises a first dielectric layer (1341) between the first conductor layer (1310) and the emissive layer (1330) and a second dielectric layer (1342) between the second conductor layer (1320) and the emissive layer (1330) , and the emissive layer (1330) comprises an electroluminescent phosphor material.

6. A phosphor screen (1000) according to the preceding claim, wherein the electroluminescent phosphor material comprises one or more inorganic electroluminescent phosphor materials, such as one or more metal-doped zinc sulfides, e.g., manganese-doped zinc sulfide, ZnS:Mn; copper-doped zinc sulfide, ZnS:Cu; ter- bium-doped zinc sulfide, ZnS:Tb; europium-doped zincsulfide, ZnS:Eu; and/or silver-doped zinc sulfide, ZnS : Ag .

7. A phosphor screen (1000) according to any of the preceding claims, wherein the scintillator layer (1200) comprises one or more cathodoluminescent scintillator materials, such as one or more inorganic cathodoluminescent materials, e.g., manganese-doped zinc silicate, Z^SiCg Mn; calcium tungstate, CaWCg; silver-doped zinc sulfide, ZnS:Ag; manganese-doped potassium magnesium fluoride, KMgFs Mn; aluminum and copper co-doped zinc sulfide, ZnS:Cu,Al; europium-doped yttrium oxide sulfide, Y2<32S:Eu; manganese and lead codoped calcium metasilicate, CaSiCg :Mn, Pb; copper-doped zinc sulfide, ZnS:Cu; manganese-doped magnesium fluoride, MgF2:Mn; manganese and arsenide co-doped zinc silicate, Zn2SiO4 : Mn, s ; manganese and indium co-doped zinc silicate, Z^SiCg :Mn, In; terbium-doped gadolinium oxysulfide, Gd2O2S:Tb; terbium-doped lanthanum oxysulfide, La22O2S:Tb; terbium-doped yttrium oxide sulfide, Y2O2S:Tb; terbium and europium co-doped yttrium oxide sulfide, Y2O2S:Tb,Eu; cerium-doped yttrium aluminum garnet, YsAlsO^Ce; cerium-doped yttrium orthosilicate, Y2SiOs:Ce; and/or europium-doped yttrium oxide, Y₂O3:EU.

8. A phosphor screen (1000) according to any of the preceding claims, wherein the first conductor layer (1310) and the second conductor layer (1320) are transparent .

9. An imaging device (3000) comprising a phosphor screen (3130) in accordance with any of the preceding claims.

10. An imaging device (3000) according to claim 9 implemented as an infrared viewer.

11. A method (4000) for fabricating a phosphor screen, the method (4000) comprising:

- providing a transparent substrate (4100) ;

- forming a transparent display element (4200) supported by the substrate, the process of forming a transparent display element (4200) comprising o forming a first conductor layer (4210) , o forming an emissive layer (4220) , and o forming a second conductor layer (4230) such that the emissive layer is arranged between the first conductor layer and the second conductor layer; and - forming a scintillator layer (4300) supported by the substrate.

12. A method (4000) according to claim 11, wherein one or more of the processes of forming a first conductor layer (4210) , forming an emissive layer (4220) , and forming a second conductor layer (4230) comprises an atomic layer deposition (4211, 4221, 4231) step.

13. A method (4000) according to claim 11 or 12, wherein the phosphor screen is a phosphor screen (1000) in accordance with any of claims 1 to 8.