Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
  • H01J29/006—Arrangements for eliminating unwanted temperature effects
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
  • H01J1/02—Main electrodes
  • H01J1/30—Cold cathodes, e.g. field-emissive cathode
  • H01J1/304—Field-emissive cathodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
  • H01J29/86—Vessels; Containers; Vacuum locks
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J61/00—Gas-discharge or vapour-discharge lamps
  • H01J61/02—Details
  • H01J61/52—Cooling arrangements; Heating arrangements; Means for circulating gas or vapour within the discharge space
  • H01J61/523—Heating or cooling particular parts of the lamp
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J63/00—Cathode-ray or electron-stream lamps
  • H01J63/02—Details, e.g. electrode, gas filling, shape of vessel
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J63/00—Cathode-ray or electron-stream lamps
  • H01J63/06—Lamps with luminescent screen excited by the ray or stream
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2329/00—Electron emission display panels, e.g. field emission display panels
  • H01J2329/002—Cooling means

Definitions

• the present invention relates to an improved field emission lighting arrangement. More specifically, the invention relates to a field emission lighting arrangement which has been adapted for improved heat dissipation during operation.
• Florescent light sources also in forms resembling the traditional light bulb have been shown and are often referred to as compact fluorescent lamps (CFLs).
• CFLs compact fluorescent lamps
• all florescent light sources contain a small amount of mercury, posing problems due to the health effects of mercury exposure. Additionally, due to heavy regulation of the disposal of mercury, the recycling of florescent light sources becomes complex and expensive.
• the field emission light source includes an anode and a cathode, the anode consists of a transparent electrically conductive layer and a layer of phosphors coated on the inner surface of a cylindrical glass tube.
• the phosphors are luminescent when excited by electrons.
• the electron emission is caused by a voltage between the anode and the cathode. For achieving high emission of light it is desirable to apply the voltage in a range of 4 - 12 kV.
• the field emission light source disclosed in WO 2005074006 provides a promising approach to more environmentally friendly lighting, e.g. as no use of mercury is necessary. However it is always desirable to improve the design of the lamp to prolong the life time, and/or to increase the luminous efficiency of the lamp.
• a field emission lighting arrangement comprising an evacuated envelope inside of which an anode structure comprising a phosphor layer and a field emission cathode are arranged, the anode structure being configured to receive electrons emitted by the field emission cathode and to generate light when a voltage is applied between the anode structure and the field emission cathode, wherein the evacuated envelope comprises a light exit portion and a light reflective portion being adapted to reflect light generated at the anode structure, and the field emission lighting arrangement further comprises a heat sink arranged outside of the evacuated envelope and thermally coupled to the light reflective portion.
• Prior art field emission lighting arrangements are generally configured such that, during operation, the cathode emits electrons, which are
• the phosphor layer may provide luminescence when the emitted electrons collide with phosphor particles.
• the luminescence process is accompanied by the production of heat which may reduce the lifetime of the field emission lighting arrangement.
• the field emission lighting arrangements is rather configured such that light generated during operation the field emission lighting arrangement is reflected out from the field emission lighting arrangement through a light exit portion.
• This is achieved by providing a light reflective portion which serves a dual purpose, both reflecting light and being thermally connected to a heat sink for dissipating heat generated during emission of light.
• the light reflecting portion is preferably arranged in the vicinity of the anode structure, e.g. being an adjacent layer to the phosphor layer of the anode structure or being arranged outside of but in close contact to the envelope, thereby providing a direct or indirect thermal coupling to the light reflective portion.
• heat generated at the anode structure may according to the invention advantageously be dissipated using a heat transfer route starting at the phosphor layer, passing through the light reflective portion and being dissipated by the heat sink being thermally coupled to the light reflective portion.
• the field emission lighting arrangement possibly also reducing the lighting cost for the end user as the field emission lighting arrangement can be replaced at a lower rate.
• the heat sink is configured to reflect light generated at the anode structure out from the evacuated envelope through the light exit portion. Accordingly, in such an embodiment both the reflective functionality and the heat sink may be arranged outside of the envelope, possibly being provided as a single component.
• anode structure may alternatively be configured to reflect light generated at the anode structure out from the evacuated envelope through the light exit portion, thus providing the reflective functionality inside of the envelope and the heat sink outside of the envelope.
• a reflective anode structure may for example comprise a metal layer arranged inside of the envelope, for example aluminum or one of its alloys, or other metallic materials deposited on the inner surface of the envelope.
• the heat sink may be selected from a plurality of known heat dissipating materials and be constructed in any suitable form.
• the heat sink comprises a heat dissipating carbon based compound, possibly pressed to a suitable form matching the form of the field emission lighting arrangement.
• the field emission lighting arrangement further comprises a power supply connected to the field emission cathode and the anode structure and configured to provide a drive signal for powering the field emission lighting arrangement.
• the configuration and the physical dimensions of the field emission lighting arrangement are determined; the physical properties of the field emission lighting arrangement may be determined. From the electric circuit point of view, some of these properties may be identified with those of electronic components, like a diode, capacitor and inductor with predetermined resistance, capacitance and inductance.
• any frequency below the resonance frequency is defined as low frequency.
• a desired predetermined (resonance) frequency and a phase relation between the input voltage and the current is further disclosed in EP09180155 by the applicant, which is incorporated by reference in its entirety. Accordingly, it may be preferred to select the predetermined frequency such that it is within a range
• the predetermined frequency may also be selected to depend on an emission decay of the phosphor layer.
• the emission decay for a phosphor layer suitable for a field emission arrangement takes place in a range of micro seconds thus indicating a high predetermined frequency.
• the predetermined frequency is preferably selected to be above 10 kHz and preferably above 30 kHz.
• the envelop is made of glass and the voltage is preferably in the range of 2 - 12 kV.
• the power supply may be electrically connected or in physical contact to the field emission arrangement, such as for example within a socket/base/side in the case the field emission arrangement is a field emission light source or placed in the vicinity of the field emission arrangement.
• the field emission lighting arrangement may be compactly integrated as a single component, e.g. as a luminaire for lighting, or as a backlight for a display. Additionally, the field emission lighting arrangement according to the invention may preferably forms part of any lighting requiring application, including for example a field emission display, an X-ray source. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled addressee realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.
• Fig. 1 illustrates a prior art field emission lighting arrangement
• Fig. 2 illustrates a currently preferred embodiment of the field emission lighting arrangement
• Fig. 3 illustrates an alternative embodiment of the field emission lighting arrangement.
• the field emission lighting arrangement 100 is based on the concept of using a transparent field emission anode, such as an ITO layer 102 being provided on a transparent envelope, such as an evacuated cylindrical glass tube 104 (envelope).
• a transparent field emission anode such as an ITO layer 102 being provided on a transparent envelope, such as an evacuated cylindrical glass tube 104 (envelope).
• a layer of phosphor 106 is provided on the inside of the ITO layer 102, facing a field emission cathode 108.
• the field emission cathode 108 comprises a base structure onto which pluralities of sharp edges are arranged, for example a ZnO based emitter structure as disclosed in
• EP10159139 by the applicant, which is incorporated by reference in its entirety.
• an electrical field is applied between the cathode 108 and an anode structure, e.g. the transparent ITO layer 102 (acting as an electrode) for example by means of a control unit and power supply (not shown).
• an anode structure e.g. the transparent ITO layer 102 (acting as an electrode) for example by means of a control unit and power supply (not shown).
• the cathode 108 emits electrons, which are accelerated toward a phosphor layer 106 of the anode structure.
• the phosphor layer 106 may provide luminescence when the emitted electrons collide with phosphor particles of the phosphor layer 106.
• Light provided from the phosphor layer 106 will transmit through the transparent ITO/anode structure 102 and a glass cylinder 104 acting as a substrate for the anode structure.
• the light is preferably white, but colored light is of course possible.
• the light may also be UV light.
• FIG. 2 illustrates a currently preferred
• the field emission lighting arrangement 200 provides similarities with the field emission lighting arrangement 100 shown in Fig. 1 but has been adapted for achieving a higher heat dissipation during operation of the field emission lighting arrangement 200, thus possibly increasing its lifetime.
• the main difference between the illustrated field emission lighting arrangement 200 and the field emission lighting arrangement 100 of figure 1 is that the field emission lighting arrangement 200 has been provided with a heat sink 204 for example comprising heat sink flanges 206.
• the heat sink 204 may for example be provided such that it encloses a portion of the glass cylinder 104, thereby being thermally coupled to each other.
• the portion of the glass cylinder 104 where the anode structure has been provided coincides with the portion of the glass cylinder 104 which is thermally coupled to the heat sink 204.
• the portion of the glass cylinder 104 being thermally coupled to the heat sink 204 is around 1/3 to 1/2 of the perimeter of the glass cylinder 104.
• Other arrangements are of course possible and within the scope of the invention.
• a further difference between the field emission lighting arrangement 200 and the field emission lighting arrangement 100 shown in Fig. 1 is that the ITO electrode layer 102 has been replaced with a reflective anode electrode 202, for example in the form of a metal layer, such as aluminum, being provided on the inside of the glass cylinder 104.
• a reflective anode electrode 202 for example in the form of a metal layer, such as aluminum, being provided on the inside of the glass cylinder 104.
• the electrons emitted from the cathode 108 will travel towards the reflective anode electrode 202 to strike the phosphor layer 106 such that light is emitted.
• the light will be reflected by the reflective anode electrode 202 towards the outside of the field emission lighting arrangement 200.
• Heat generated during operation of the field emission lighting arrangement 200 at the phosphor layer 106 and the reflective anode electrode 202 will be at least partly dissipated by means of the heat sink 204 and heat sink flanges 206 thermally coupled to the glass cylinder 104.
• the reflective anode structure 202 can be made of a highly reflective metallic layer such as aluminum.
• a transparent anode structure 302 is used, for example an ITO layer.
• the heat sink 204 has been provided with a reflective layer 304 which thereby will reflect the light out towards the side opposite of the heat sink 204.
• the reflective layer 304 may for example be provided onto a heat dissipating carbon based compound for example being formed to the heat sink 204.
• the reflective layer 304 may also be an integrated portion of e.g. a metal based heat sink.

Landscapes

• Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
• Discharge Lamps And Accessories Thereof (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=43587361

Family Applications (1)

Country Status (2)

Citations (7)

Family Cites Families (2)

• 2010
  • 2010-12-28 EP EP10197167A patent/EP2472552A1/de not_active Withdrawn
• 2011
  • 2011-12-07 WO PCT/EP2011/072058 patent/WO2012089467A1/en active Application Filing

Patent Citations (7)

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