Patent Publication Number: US-9903564-B2

Title: Lamp as well as a method for using such a lamp

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2014/077445, filed on Dec. 11, 2014, which claims the benefit of European Patent Application No. 14150894.5, filed on Jan. 13, 2014. These applications are hereby incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The invention relates to a lamp comprising at least one light source adapted for emitting optical radiation, at least one scanning mirror, a fluorescent body and optical means for transmitting at least a portion of the optical radiation being directed from the light source by the scanning mirror onto the fluorescent body to an output of the lamp. 
     The invention also relates to a method for using such a lamp. 
     BACKGROUND OF THE INVENTION 
     US20120026721A1 discloses a lamp comprising a laser, a fluorescent body and a parabolic reflector, wherein optical radiation emitted by the laser is converted by the fluorescent body into visible light, which visible light is reflected by the parabolic reflector to an output of the lamp. The fluorescent body comprises a longitudinal cylindrical-shaped body. By the lamp according to US20120026721A1 the laser may comprise a scanning mirror for scanning or widening the laser beam over the fluorescent body resulting in slight changes in the beam profile. 
     By the lamp according to US20120026721A1 the beam profile can only be slightly changed. With the slightly changes, the collimation of the beam can be slightly adapted. The center of the beam can not be adjusted and the beam can also not be split into several beams. 
     US2011249460A1 dislcoses a lamp comprising two blue lasers emitting radiation towards two MEMS mirrors, which reflect said radiation corresponding to a prescribed light distribution pattern onto a phosphor panel, which pattern subsequently is projected in a light emitting direction via a projector lens. 
     SUMMARY OF THE INVENTION 
     In view of the above-mentioned and other drawbacks of the prior art, a general object of the present invention is to provide a lamp for creating a redirectable spot or relatively complex light beam formations such as squares, logo&#39;s etc. 
     According to a first aspect, the invention provides a lamp wherein the fluorescent body is plate-shaped, whilst the optical means comprises at least one lens, wherein each part of the plate-shaped fluorescent body can be imaged by the at least one lens in a predetermined direction to the output of the lamp wherein the plate-shaped fluorescent body is rotatable about a central axis extending perpendicular to the plate-shaped fluorescent body, wherein the central axis coincides with the optical axis of the at least one lens. 
     By means of the at least one scanning mirror, the optical radiation of the light source can be directed to each part of the plate-shaped fluorescent body. On the plate-shaped fluorescent body the optical radiation of the light source is converted into visible light. By the at least one lens, the part of the plate-shaped fluorescent body is being imaged in a predetermined direction to the output of the lamp. 
     By sequentially directing the optical radiation of the light source with the at least one scanning mirror to different predetermined parts of the plate-shaped fluorescent body a desired relatively complex light beam formation such as squares, logo&#39;s etc. can be created. 
     It is also possible to direct the optical radiation of the light source with the at least one scanning mirror continuously to only a relatively small predetermined part of the plate-shaped fluorescent body, whereby a light spot is being created. The spot can be redirected by directing the optical radiation of the light source with the at least one scanning mirror to another relatively small predetermined part of the plate-shaped fluorescent body. 
     In case that the optical radiation of the light source is directed with the at least one scanning mirror to a specific position on the plate-shaped fluorescent body, the part of the plate-shaped fluorescent body on said specific position may be heated up too much leading to a reduction of the life time of the lamp. By rotating the plate-shaped fluorescent body the optical radiation of the light source is still directed with the at least one scanning mirror to the same specific position but will illuminate different parts on the same radius of the plate-shaped fluorescent body, whereby the heat will be spread over the radius. 
     According to a further aspect, the invention provides a lamp wherein the plate-shaped fluorescent body is transmissive, whereby optical radiation from the light source is being transmitted through the plate-shaped fluorescent body to the at least one lens. 
     With a transmissive plate-shaped fluorescent body, the construction of the lamp is relatively simple, wherein an optical axes of light source, fluorescent body and the at least one lens can be coaxially located. 
     According to a further aspect, the invention provides a lamp wherein on a side of the plate-shaped fluorescent body optically directed towards the light source a reflective polarization filter is located. 
     When using a light source with polarized light, a part of the polarized light will be transmitted through the transmissive plate-shaped fluorescent body whilst another part will be reflected by the fluorescent body towards the light source. The reflected light will be unpolarized. By using a reflective polarization filter the reflected unpolarized light will be partly reflected by the polarization filter and will still be transmitted through the fluorescent body. In this way loss of optical radiation is being reduced. 
     According to a further aspect, the invention provides a lamp wherein the light source is adapted for emitting right-handed or left-handed circularly polarized optical radiation, wherein the reflective polarization filter is a reflective circular polarization filter. 
     When rotating the fluorescent body together with reflective circular polarization filter, a part of the circularly polarized optical radiation will be transmitted through the reflective circular polarization filter and the fluorescent body, whilst another part will be reflected by the fluorescent body towards the light source. The reflected optical radiation will be unpolarized. The reflected unpolarized optical radiation will be partly reflected by the polarization filter and will still be transmitted through the fluorescent body. 
     According to a further aspect, the invention provides a lamp wherein on a side of the plate-shaped fluorescent body optically directed towards the light source a dichroic filter is located. 
     By such a dichroic filter optical radiation reflected by the fluorescent body towards the light source will be reflected by dichroic filter towards the fluorescent body and will still be transmitted through the fluorescent body. 
     According to a further aspect, the invention provides a lamp wherein the plate-shaped fluorescent body is reflective, whereby optical radiation from the light source is being reflected by the plate-shaped fluorescent body to the at least one lens. 
     With a reflective fluorescent body nearly all optical radiation will be reflected towards the at least one lens and nearly no optical radiation will be lost in the fluorescent body. 
     According to a further aspect, the invention provides a lamp wherein the light source is optically located on a first side of the plate-shaped fluorescent body, whilst the at least one lens is optically located on a second side of the plate-shaped fluorescent body, wherein the plate-shaped fluorescent body is provided with an aperture for guiding optical radiation emitted by the light source from the first side to the second side. 
     Due to said aperture a plate-shaped fluorescent body being reflective at the second side can be used whilst the light source is located on the first side, providing a relatively simple lamp. 
     According to a further aspect, the invention provides a lamp wherein the at least one scanning mirror is located between the at least one lens and the second side. 
     The optical radiation emitted by the light source will firstly pass the aperture after it is being directed by the at least one scanning mirror to the desired parts on the fluorescent body. In this manner the aperture can be relatively small. 
     According to a further aspect, the invention provides a lamp wherein the at least one scanning mirror is located at the fist side, whilst an additional mirror is located between the at least one lens and the second side. 
     In this manner the at least one scanning mirror can be located relatively close to the light source for mechanical simplicity. 
     According to a further aspect, the invention provides a lamp wherein the plate-shaped fluorescent body is provided with phosphor. 
     Phosphor can easily be applied to a plate-shaped element to obtain the plate-shaped fluorescent body. Furthermore, with phosphor optical radiation from a light source, for example a laser, can easily be converted into light with a desired wavelength. 
     According to a further aspect, the invention provides a lamp wherein the plate-shaped fluorescent body is provided with different phosphors in a predetermined pattern. 
     By means of the at least one scanning mirror, the optical radiation of the light source can be directed to the desired phosphor for generating for example a specific colour. When the plate-shaped fluorescent body is being rotated, the part with the desired phosphor can be moved to the desired position before being illuminated. 
     According to a further aspect, the invention provides a lamp wherein the light source is a blue laser or a UV laser. 
     Such a light source provided light with a relatively high colour rendering index (CRI) and are easily available at reasonable costs. 
     According to a further aspect, the invention provides a lamp wherein the light source can be modulated in intensity. 
     In this manner it is possible to obtain modulated optical radiation to enable for example multiple different light beams or the possibility to write complex light patterns. 
     According to a further aspect, the invention provides a lamp wherein the wavelength of the optical radiation emitted by the light source is adjustable. 
     In this manner different conversion will occur on the fluorescent body depending on the wavelength of the optical radiation and different colour temperatures can be obtained, for example to obtain cold or warm white light. 
     According to a further aspect, the invention provides a lamp wherein the lamp comprises a control device for controlling the laser, the at least one scanning mirror and/or rotation of the plate-shaped fluorescent body about a central axis extending perpendicular to the plate-shaped fluorescent body, wherein the central axis coincides with the optical axis of the at least one lens. 
     By means of the control device the wavelength of the light source can be adjusted and/or the intensity of the light source can be modulated. Furthermore by means of the control device the movements of the at least scanning mirror for scanning the optical radiation to each desired part of the plate-shaped fluorescent body can be controlled. When the plate-shaped fluorescent body is being rotated, the rotation in frequency and position can be controlled by the control device and can be synchronized with the control of the light source and the at least scanning mirror so that to at each position a desired optical radiation with the desired wavelength and being modulated in intensity can be directed, whilst at the desired position due to rotation of the fluorescent body a part of the fluorescent body can be present with the desired phosphor. 
     According to a further aspect, the invention provides a method for using a lamp comprising the steps:
     a) emitting optical radiation by a light source, and   b) transmitting at least a portion of optical radiation via at least one scanning mirror, a plate-shaped fluorescent body and at least one lens to an output of a lamp.   

     Due to this method a redirectable spot or relatively complex light beam formations such as squares, logo&#39;s etc. can be created. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects of the invention will now be described in more detail, with reference to the appended drawings showing currently preferred embodiments of the inventions, wherein: 
         FIG. 1  shows a schematic view of a first embodiment of a lamp according to the invention with a transmissive plate-shaped fluorescent body, 
         FIG. 2  shows a schematic view of a second embodiment of a lamp according to the invention with a transmissive plate-shaped fluorescent body and a polarization filter, 
         FIGS. 3-5  show a schematic views of a third, fourth and fifth embodiment of a lamp according to the invention with a reflective plate-shaped fluorescent body comprising an aperture, 
         FIGS. 6 and 7  show a schematic views of a sixth and seventh embodiment of a lamp according to the invention with a reflective plate-shaped fluorescent body and no aperture. 
     
    
    
     In the drawings, like reference numerals refer to like elements. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a schematic view of a first embodiment of a lamp  1  according to the invention comprising a light source  2 , at least one scanning mirror  3  being driven by at least one motor M 1 , a plate-shaped fluorescent body  4  and at least one lens  5 . The plate-shaped fluorescent body  4  is rotatable by means of a motor M 2  in the direction as indicated by arrow R bout a rotating axis  6 . The rotating axis  6  extends perpendicular to the plate-shaped fluorescent body  4 . 
     For sake of simplicity only scanning mirror  3  and only one motor M 1  is being shown but a person skilled in the art will realize that any desired set of scanning mirrors with a number of motors can be used to move optical radiation emitted by the light source  2  to any desired location on the plate-shaped fluorescent body  4 . 
     The plate-shaped fluorescent body  4  is transmissive for optical radiation emitted by the light source  2 . 
     For sake of simplicity only one lens  5  is being shown but a person skilled in the art will realize that any desired set of lenses can be used. The rotating axis  6  is coaxial with the optical axis  7  of the lens  5 . 
     The light source  2  is a laser with adjustable wavelengths and modulated intensity. The light source  2  is being controlled by control device C. The motors M 1 , M 2  of the scanning mirror  3  and the rotatable plate-shaped fluorescent body  4  are also controlled by control device C. 
     The plate-shaped fluorescent body  4  is provided with different phosphors in a predetermined pattern. 
     When operating the lamp  1  according to the invention the light source  2  emits optical radiation with the desired wavelength and intensity towards the scanning mirror  3 . The light beam  8  comprising the optical radiation has a diameter for example  1  millimeter. By means of the scanning mirror  3  the light beam  8  is directed towards a desired position on plate-shaped fluorescent body  4 , which will be imaged by means of the lens  5  towards an output  9  of the lamp  1 . The desired position is a position with predetermined coordinates with respect to for example the light source  2  or the lens  5  and is independently of the angle of rotation of the plate-shaped fluorescent body  4 . By controlling the rotation of the he plate-shaped fluorescent body  4  a part of the plate-shaped fluorescent body  4  with the desired phosphor pattern can be moved towards the desired position so that the light beam  8  hits said desired part of the plate-shaped fluorescent body  4 . The illuminated part is than imaged by the lens  5  towards the output  9  of the lamp  1 . 
     The plate-shaped fluorescent body  4  has a diameter for example in the range of 1 to 10 centimeter. 
     By the control device the operation of the light source  2 , the scanning mirror  3  and the rotation of the plate-shaped fluorescent body  4  is being controlled so that at each moment at the desired position a desired light beam  8  will hit the plate-shaped fluorescent body  4  at the desired part. 
     The light source  2  can be scanned over the plate-shaped fluorescent body  4  with a frequency for example in the range of 60-500 Hertz. The plate-shaped fluorescent body  4  can be rotated with a frequency for example in the range of 1-10 Hertz. 
     The  FIGS. 2-7  show schematic view of other embodiments of lamps according to the invention. In these figures the motors M 1 , M 2  and the control device C are not shown but all these embodiments do comprise the motors M 1 , M 2  and the control device C. 
       FIG. 2  shows a schematic view of a second embodiment of a lamp  21  according to the invention, which lamp  21  differs from lamp  1  in that it is provided with a reflective circular polarization filter  22  located on a side of the plate-shaped fluorescent body  4  optically directed towards the light source  2 . The reflective circular polarization filter  22  is connected to the plate-shaped fluorescent body  4  at a short distance of less than  1  centimeter thereof and is being rotatable together with the plate-shaped fluorescent body  4  about rotating axis  6  in the direction indicated by arrow R. The light source  2  is adapted for emitting circularly polarized optical radiation being similar right-handed or left-handed as the reflective circular polarization filter  22 . 
     The circularly polarized light beam  8  directed by the scanning mirror  3  to the desired position will pass the reflective circular polarization filter  22  and will be partly transmitted through the plate-shaped fluorescent body  4 . A part  23  of the light beam  8  will be reflected by the plate-shaped fluorescent body  4 . This part  23  of the light beam  8  is unpolarized and will be reflected by the reflective circular polarization filter  22  as part  24  towards the plate-shaped fluorescent body  4  and will be transmitted through the plate-shaped fluorescent body  4 . A small part  25  will pass the reflective circular polarization filter  22  and will be lost. However less optical radiation will get lost than by the lamp  1 . For example, in case that the circularly polarized light beam  8  is right-handed, the part  23  of the light beam  8  reflected by the plate-shaped fluorescent body  4  will be partly right-handed and partly left-handed. The right-handed part  25  will pass the reflective circular polarization filter  22  and will be lost. The left-handed-part  24  will be reflected by the reflective circular polarization filter  22  towards the plate-shaped fluorescent body  4 . By the reflective circular polarization filter  22  50% of part  23  of the light beam  8  reflected by the plate-shaped fluorescent body  4  will be reflected towards the plate-shaped fluorescent body  4 . 
       FIG. 3  shows a schematic view of a third embodiment of a lamp  31  according to the invention which lamp  31  differs from lamp  1  in that it is provided with a reflective plate-shaped fluorescent body  34  comprising a central aperture  35 . 
     The scanning mirror  3  is located near the lens  5  and near the optical axis  7 . 
     When operating the lamp  31  the light source  2  emits optical radiation as a light beam  8 . The light beam  8  passes the aperture  35  and is than directed by the scanning mirror  3  towards the desired position on reflective side of the plate-shaped fluorescent body  34 . The illuminated part of the plate-shaped fluorescent body  34  is than imaged by means of the lens  5  towards the output  9  of the lamp  31 . 
       FIG. 4  shows a schematic view of a fourth embodiment of a lamp  41  according to the invention which lamp  41  differs from lamp  31  by the positions of the light source  2  and the scanning mirror  3 . The light beam  8  emitted by the light source  2  encloses an angle A of about  45  degrees with the plate-shaped fluorescent body  34 . 
     The scanning mirror  3  is located between the plate-shaped fluorescent body  34  and the lens  5  at a distance of the optical axis  7 . 
     When operating the lamp  41  the light source  2  emits optical radiation as a light beam  8 . The light beam  8  passes the aperture  35  and is than directed by the scanning mirror  3  towards the desired position on reflective side of the plate-shaped fluorescent body  34 . The illuminated part of the plate-shaped fluorescent body  34  is than imaged by means of the lens  5  towards the output  9  of the lamp  41 . 
       FIG. 5  shows a schematic view of a fifth embodiment of a lamp  51  according to the invention which lamp  51  differs from lamp  41  by the position of the scanning mirror  3  and an additional spherical mirror  52  near the lens  5  and near the optical axis  7  thereof. The scanning mirror  3  is located relatively close to the light source and near the aperture  35 . 
     When operating the lamp  51  the light source  2  emits optical radiation as a light beam  8 . The light beam  8  is directed by the scanning mirror  3  through the aperture  35  towards the additional spherical mirror  52 . The light beam  8  is reflected by the additional spherical mirror  52  towards the desired position on reflective side of the plate-shaped fluorescent body  34 . The illuminated part of the plate-shaped fluorescent body  34  is imaged by means of the lens  5  towards the output  9  of the lamp  51 . 
       FIG. 6  shows a schematic view of a sixth embodiment of a lamp  61  according to the invention which lamp  61  differs from lamp  1  in that the plate-shaped fluorescent body  64  is reflective instead of transmissive like the plate-shaped fluorescent body  4 . Furthermore, the laser  2  and scanning mirror  3  are located in a manner to be able to direct the light beam  8  from the light source  2  via the scanning mirror  3  on the reflective side of the plate-shaped fluorescent body  64 . The reflective side of the plate-shaped fluorescent body  64  is optically directed towards the lens  5 . By the lamp  61  the light source  2  and the scanning mirror  3  are located on the same side of the optical axis  7  above the plate-shaped fluorescent body  64 . 
       FIG. 7  shows a schematic view of a seventh embodiment of a lamp  71  according to the invention which lamp  71  differs from lamp  61  in that the light source  2  and the scanning mirror  3  are located on different sides of the optical axis  7  and the light beam  8  form the light source  2  is directed perpendicular to the optical axis  7 . 
     The light source can also be a blue laser or a UV laser. 
     It is also possible that the plate-shaped fluorescent body is provided with identical phosphors over the whole plate-shaped fluorescent body. 
     It is also possible that the plate-shaped fluorescent body is not being rotated. 
     It is also possible that the light source is another very clear light sources with 1 Watt and 1 millimeter in diameter, for example a luxeon light source. 
     It is also possible to use more than one source, whereby the optical radiation of each light source can be directed by scanning mirrors to the desired part of the fluorescent body. 
     In case of that the fluorescent body  4  is not being rotated at all, the plate-shaped fluorescent body  4  can also be made of a square or rectangular plate. 
     The person skilled in the art will realize that the present invention is by no means limited to the preferred embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. 
     In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the scope should not be construed as limiting the scope of the claims. 
     LIST OF REFERENCE SIGNS 
     
         
           1  lamp 
           2  light source 
           3  scanning mirror 
           4  plate-shaped fluorescent body 
           5  lens 
           6  central axis 
           7  optical axis 
           8  light beam 
           9  output 
           21  lamp 
           22  polarization filter 
           23  part of light beam 
           24  part of light beam 
           25  part of light beam 
           31  lamp 
           34  plate-shaped fluorescent body 
           35  aperture 
           41  lamp 
           51  lamp 
           52  spherical mirror 
           61  lamp 
           64  plate-shaped fluorescent body 
           71  lamp 
         A angle 
         C control device 
         M 1  motor 
         M 2  motor 
         R arrow