WO2014120083A1

WO2014120083A1 - Miniaturized xenon flash module

Info

Publication number: WO2014120083A1
Application number: PCT/SG2013/000041
Authority: WO
Inventors: Young Chung KIM; Kim Guan LIM
Original assignee: Xenon Technologies Pte Ltd
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2014-08-07

Abstract

A xenon flash module for use in an image capturing device which comprises a lens housing. The lens housing has a protruding portion that forms a lens window. The lens housing and the lens window define an interior, and the interior comprises a reflector arranged adjacent to a xenon lamp. The interior also comprises a reflector cover that substantially encapsulates the reflector; and a plurality of electronic components mounted on a printed circuit board. Wherein the lens window has a recess, and the recess is adapted to receive a portion of the reflector, and the reflector is arranged such that the portion of the reflector extends into the recess.

Description

MINIATURIZED XENON FLASH MODULE

FIELD OF THE INVENTION

[0001] The present invention relates to xenon flash modules, particularly to xenon flash modules used in portable image capturing devices. Image capturing devices can be, but not limited to, digital cameras, smart phones, cell phones, PDAs, pagers, tablets, messenger devices, handhelds and the like.

BACKGROUND

[0002] Flash lamps are discharge lamps that produce highly intensive light with very short duration and are used extensively in photography. Xenon flash modules incorporating xenon flash lamps are used in digital cameras for its reliability and ability to mimic natural sunlight thereby resulting in better image quality for capturing quick moving objects or objects in low illumination environments.

[0003] However, adoption of xenon flash modules in mobile communication devices like smart phones are not as near widespread. Instead, the bulk of smart phones (e.g. IPhone, Samsung Galaxy) use flash light-emitting diodes (LEDs) instead, as they are thinner and smaller when compared to xenon flash modules. The LEDs fit snugly within, or flush with the phone casing. Consumer demand for design appeal and thinner profiles therefore contributes to xenon flash modules not being as nearly as popular in the smart phones market, in spite of the fact that xenon flash modules produce superior flash intensities and better image quality than LEDs.

[0004] There is therefore a need to miniaturize the xenon flash module, and make it thinner and smaller. SUMMARY OF INVENTION

[0005] According to a first aspect of the present invention, a xenon flash module for use in an image capturing device is described, the xenon flash module comprising a lens housing having a protruding portion that forms a lens window, the lens housing and lens window defining an interior. The interior comprises a reflector arranged adjacent to a xenon lamp, a reflector cover that substantially encapsulates the reflector, and a plurality of electronic components mounted on a printed circuit board. Wherein the lens window has a recess, the recess adapted to receive a portion of the reflector, and the reflector is arranged such that the portion of the reflector extends into the recess.

[0006] Preferably, the portion of the reflector extends into the recess fully such that it contacts a inner flat surface of the lens window.

[0007] Preferably, the lens housing comprises an inner wall, and the inner wall is joined to the reflector cover to form a junction, the junction having a gap.

[0008] Preferably, the xenon flash module comprises a filler, the filler arranged between the gap and the plurality of electronic components.

[0009] Preferably, the filler is arranged such that the plurality of electronic components is encapsulated by the filler.

[0010] Preferably, the xenon flash module comprises a gasket which plugs the gap.

[001 1] Preferably, the printed circuit board is flexible and has a first side and a second side, and the plurality of electronic components are mounted on only the first side of the printed circuit board, and the printed circuit board is positioned beside the reflector cover and bent in a U-shaped manner such that the second side of the printed circuit board substantially traces a inner side wall of the lens housing.

[0012] Preferably, the filler is an epoxy resin or an adhesive rubber.

[0013] Preferably, the xenon flash module comprises a slim electrolytic capacitor. [0014] Preferably, the xenon lamp comprises disc-like electrodes.

[0015] Preferably, an external surface of the lens window is substantially flush with an external surface of the image capturing device such that the lens window does not protrude out from the image capturing device.

[0016] The invention will now be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying figures illustrate disclosed embodiment(s) and serve to explain principles of the disclosed embodiment(s). It is to be understood, however, that these drawings are presented for purposes of illustration only, and not for defining limits of the application.

[0018] Figure 1 is a perspective view of a xenon flash module currently used in the art;

[0019] Figure 2 is a cross-sectional view of xenon flash module of Figure 1 taken along section A-A' arranged relative to a phone cover casing;

[0020] Figure 3 is a perspective view of a xenon flash module in accordance with a preferred embodiment of the invention;

[0021] Figure 4 is a cross-sectional view of xenon flash module of Figure 3 taken along section B-B' arranged relative to a phone cover casing;

[0022] Figure 5 is cross-sectional view of xenon flash module of Figure 3 taken along section B-B' arranged relative to a phone cover casing;

[0023] Figure 6 is cross-sectional view of xenon flash module of Figure 3 taken along section B-B' arranged relative to a phone cover casing; [0024] Figure 7(a) shows a cross-sectional view of xenon flash module of Figure 3 < taken along section Q-Q'. Figure 7(b) shows a perspective view of one side of a conventional xenon lamp with a cylindrical-like electrode;

[0025] Figure 8(a) shows a cross-sectional view of xenon flash module of Figure 3 taken along section Q-Q'. Figure 8(b) shows a perspective view of one side of a xenon lamp with a disc-like electrode.

[0026] Exemplary, non-limiting embodiments of the present application will now be described with references to the above-mentioned figures.

DETAILED DESCRIPTION

[0027] Referring to the drawings, Figure 1 show a perspective view of xenon flash module 100 currently used in the art. Xenon flash module 100 has lens housing 101 and cylindrical electrolytic capacitor 11 1. Lens housing 101 has a protruding transparent portion that forms lens window 102. Lens window 102 is made up of glass or plastic.

[0028] Figure 2 shows a cross-sectional view of xenon flash module 100 of Figure 1 taken along section A-A', arranged relative to phone cover casing 10. Although cylindrical electrolytic capacitor 1 1 1 is part of xenon flash module 100, it is not shown in Figure 2. The dimensions "thickness" and "width" of a xenon flash module are also indicated in Figure 2 to avoid any confusion with this terminology which is used throughout the specifications.

[0029] Lens window 102 has Fresnel lens pattern 103. The interior of lens housing

101 comprises xenon lamp 104, reflector 105, reflector cover 106, printed circuit board 107 and electronic components 108. Bottom wall 109 seals lens housing 101. Xenon lamp 104 is a tubular hollow glass body containing xenon gas, and provides the light source for xenon flash module 100. Wiring (not shown) connects xenon lamp 104 to printed circuit board 107 and thereto a power source.

[0030] The function of reflector 105 is to reflect and thereby concentrate the flash (or light) emitted by xenon lamp 104 towards lens window 102. Reflector 105 is usually made up • of aluminum for its excellent light-reflectance. Reflector 105 can have a U-shaped or parabolic cross-section, and can have a rectangular or oval-shaped top surface.

[0031] Reflector cover 106 substantially encapsulates reflector 105. Reflector cover

106 is usually made up of a high dielectric material and the function of reflector cover 106 is to shield electronic components 108 from the high voltage present in reflector 105. Reflector cover 106 is mounted on top of printed circuit board 107. Electronic components 108 is for the effective functioning of the xenon flash module 100 and are soldered onto the top and bottom surfaces of printed circuit board 107. Examples of electronic components 108 are diodes, resistors, transformer, trigger coil, charger IC and small capacitors.

[0032] From the arrangement of xenon flash module 100, it is apparent that the overall thickness of xenon flash module 100 is largely dependent on the thickness of lens window 102, the thickness of reflector 105, the thickness of reflector cover 106, the thickness of printed circuit board 107 and the thickness of electronic components 108. It is also apparent from figure 2, that there is a lot of unused space, especially in the area above electronic components 108.

[0033] There is a very small gap (not shown) between the junction of the inner wall of lens housing 101 and reflector cover 106. Such gaps are inherent whenever two separate pieces are joined together. The high voltage present in reflector 105 can pass through this gap, and potentially cause damage of electronic components 108 if electronic components 108 are too near. Clearance 110 is therefore necessary, to ensure that sufficient space exists between this gap and electronic components 108. Air (because of the unused space) has a comparatively low dielectric strength, and therefore clearance 1 10 is normally 3-4 mm.

[0034] From the arrangement of xenon flash module 100, it is apparent that the overall width of xenon flash module 100 is largely dependent on the width of printed circuit board

107 and clearance 1 10.

[0035] Referring to the drawings, Figure 3 shows a perspective view of xenon flash module 200 in accordance with a preferred embodiment of the invention. Xenon flash module 200 has lens housing 201 and slim electrolytic capacitor 222. Lens housing 201 has a protruding transparent portion that forms lens window 202. Lens window 202 is made up of glass or plastic. This^ application incorporates 'By reference PCT application^ PCT/SG2012/00294, which was filed on 21 August 2012. The specifications and drawings of PCT/SG2012/00294 provide disclosure on the features of a slim electrolytic capacitor and describe how a slim electrolytic capacitor can be made. A typical electrolytic capacitor (cylindrical electrolytic capacitor 11 1 of figure 1) has a cylindrical profile. The typical diameter or thickness of cylindrical electrolytic capacitor 111 is 5.3mm. As the capacitor is part of the xenon flash module, the thickness of cylindrical electrolytic capacitor 1 11 will therefore affect the overall thickness of xenon flash module 100. The typical diameter or thickness of slim electrolytic capacitor 222 is equal to or less than 2.5mm. Therefore, using slim electrolytic capacitor 222 will reduce the thickness of xenon flash module 200.

[0036] Figure 4 shows a cross-sectional view of xenon flash module 200 of Figure 3 taken along section B-B', arranged relative to phone cover casing 10. Although slim electrolytic capacitor 222 is part of xenon flash module 200, it is not shown in Figure 4. Xenon flash module 200 comprises lens housing 201. Lens housing 201 has a protruding transparent portion that forms lens window 202. Lens window 202 has Fresnel lens pattern

203. The thickness of lens window 202 is generally equal or slightly less than phone cover casing 10, such that when xenon flash module 200 is assembled with the phone, lens window 202 does not protrude out from phone cover casing 10. This is for aesthetic considerations and also to shield lens window 202 from impact. In the interior of lens housing 201 is xenon lamp

204, reflector 205, reflector cover 206, printed circuit board 207 and electronic components 208. Preferably, reflector cover 206 is snap fitted to lens housing 201.

[0037] Lens window 202 has recess 210 that is adapted to accommodate a portion of reflector 205. As shown in Figure 4, reflector 205 extends into recess 210 of lens window 202. In doing so, the overall thickness of xenon flash module 200 is decreased as a portion of the reflector 205 is now within recess 210 of lens window 202. Preferably, the shape of recess 210 complements the shape of that portion of reflector 205 such that that portion of reflector 205 can fit snugly into recess 210. Preferably, that portion of reflector 205 extends fully into recess 210 such that it contacts the inner flat surface of lens window 202 as shown in figure 4.

[0038] Reduction of the overall thickness of xenon flash module 200 is thus achieved without having to decrease the thickness of reflector 205. Decreasing the thickness of reflector 205 is undesirable as it will affect the amount of flash being reflected towards lens window 202. The slight drawback however, of reflector 20§ extending into recess 210, i§ that width of the lens window 202 will now have to be at least more than the full width of reflector 205, to accommodate the portion of reflector 205 (as shown in figure 4).

[0039] To lower the overall thickness of xenon flash module 200 even more, flexible printed circuit board 207 is used in place of conventional printed circuit board 107 (of figure 2). Flexible printed circuit board 207 has the advantage of being able to be bent without losing its electrical conductivity. In taking advantage of such a property, electronic components 208 are soldered onto the top surface (and not on the bottom surface) of flexible printed circuit board 207, and flexible printed circuit board 207 is bent in a U-shaped manner, such that the bottom surface of flexible printed circuit board 207 lines or traces the walls of lens housing 201 and bottom wall 209. An adhesive can be used to hold flexible printed circuit board 207 in place.

[0040] Instead of being positioned below reflector cover 206 (which was what was done in the configuration of figure 2), flexible printed circuit board 207 is now positioned beside reflector cover 206. This optimizes the use of space as seen from figure 4. Further, the overall thickness of xenon flash module 200 is thus reduced as it is no long dependent on the thickness of flexible printed circuit board 207.

[0041 ] Preferably, xenon flash module 200 has inner wall extension 21 1. Inner wall extension 21 1 is an extension of the inner wall of lens housing 201. Inner wall extension 21 1 contacts reflector cover 206. Inner wall extension 21 1 along with reflector cover 206 acts as a barrier between reflector 205 and electronic components 208.

[0042] There is an inherent gap (not shown) between the junction of inner wall extension 21 1 and reflector cover 206. The high voltage present in reflector 205 can pass through this gap, and potentially cause damage of electronic components 208. As previously shown in figure 2, clearance 1 10 was necessary to ensure that sufficient space exists between this gap and electronic components to prevent this phenomenon from occurring. However, due to its sheer length, having clearance 1 10 is counter to the invention's aim of miniaturizing xenon flash module 200. [0043] To address -this, xenon flash module 200 has filler 213 which fills up substantially the space in-between the gap and electronic components 208. Filler 213 can be any electrical insulating material. For example, filler 213 can be a resin-like epoxy, or an adhesive rubber.

[0044] The use of filler 213 reduces the necessary distance between the gap (and therefore reflector 205) and electronic components 208, as denoted by reduced clearance 212. The use of filler is able to achieve a strong enough dielectric shield such that reduced clearance 212 can be achieved and yet ensuring that electronic components 208 will not be damaged by the high voltage present in reflector 205. With reduced clearance 212, the width of xenon flash module 200 is therefore also reduced.

[0045] Figure 5 shows an alternative embodiment where the gap between the junction of inner wall extension 211 and reflector cover 206 of xenon flash module 200 is more prominent. This gap is denoted as large gap 215. Large gap 215 could be a result of the assembly process of the various parts. In this embodiment, filler 213 encapsulates electronic components 208 (as shown in figure 5) to create an air seal around electronic components 208.

[0046] In an alternative embodiment, instead of having filler 213, xenon flash module

200 has gasket 214. This is depicted in Figure 6. Gasket 214 is a shaped piece made up of rubber or other insulating material that seals the junction (and therefore gap) between inner wall extension 21 1 and reflector cover 206. The use of gasket 214 is able to achieve a strong enough dielectric shield such that reduced clearance 212 can be achieved and yet ensuring that electronic components 208 will not be damaged by the high voltage present in reflector 205.

[0047] Preferably, the xenon flash module comprises a xenon lamp which has disclike electrodes. This application incorporates by reference PCT application PCT/SG2012/000017, which was filed on 17 January 2012. The specifications and drawings of PCT/SG2012/000017 provide disclosure on the features of a xenon lamp which has disclike electrodes and describe how a xenon lamp which has disc-like electrodes can be made.

[0048] Figure 7(a) shows a cross-sectional view of xenon flash module of Figure 3 taken along section Q-Q' . Conventional xenon lamp 701 has cylindrical-like electrode 702. Figure 7(b) shows a perspective view of one side of conventional xenon lamp 701 with cylindricaHike electrade 702. The other side is symmetrical. Cylindrical-like electrode 702 is Λ*> soldered to flexible printed circuit board 703 with solder 704. To ensure a good soldering, a sufficient amount of solder 704 must have contact with cylindrical-like electrode 702.

[0049] Figure 8(a) shows a cross-sectional view of xenon flash module of Figure 3 taken along section Q-Q'. Xenon lamp 801 has disc-like electrode 802. Figure 8(b) shows a perspective view of one side of xenon lamp 801 with disc-like electrode 802. The other side is symmetrical. The surface area of disc-like electrode 802 ensures that there is contact with a sufficient amount of solder 804 to forge a strong bond with flexible printed circuit board 803. This despite the fact that disc-like electrode 802 is shorter in length than cylindrical-like electrode 702. Therefore, the use of xenon lamp 801 with disc-like electrode 802 will reduce the overall length of the xenon flash module.

[0050] Although the embodiments described herein all pertains to the xenon flash module being used in phones, one skilled in the art will appreciate that the xenon flash module can be used in all image capturing devices.

[0051] In the application, unless specified otherwise, the terms "comprising",

"comprise", and grammatical variants thereof, intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, non- explicitly recited elements.

[0052] It will be apparent that various other modifications and adaptations of the application will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the application and it is intended that all such modifications and adaptations come within the scope of the appended claims.

Claims

Claims*

1. A xenon flash module for use in an image capturing device comprising:

a lens housing having a protruding portion that forms a lens window, the lens housing and lens window defining an interior, the interior comprising:

a reflector arranged adjacent to a xenon lamp;

a reflector cover that substantially encapsulates the reflector;

a plurality of electronic components mounted on a printed circuit board;

wherein the lens window has a recess, the recess adapted to receive a portion of the reflector, and the reflector is arranged such that the portion of the reflector extends into the recess.

2. The xenon flash module of claim 1 wherein the portion of the reflector extends into the recess fully such that it contacts a inner flat surface of the lens window.

3. The xenon flash module of claim 1 or 2 wherein the lens housing further comprises an inner wall, and the inner wall is joined to the reflector cover to form a junction, the junction having a gap.

4. The xenon flash module of any one of the preceding claims further comprising a filler, the filler arranged between the gap and the plurality of electronic components.

5. The xenon flash module of claim 4 wherein the filler is arranged such that the plurality of electronic components is encapsulated by the filler.

6. The xenon flash module of any one of claims 1 to 3 further comprising a gasket which plugs the gap.

7. The xenon flash module of any one of the preceding claims wherein the printed circuit board is flexible and has a first side and a second side, and the plurality of electronic components are mounted on only the first side of the printed circuit board, and the printed circuit board is positioned beside the reflector cover and bent in a U-shaped manner such that the second side of the printed circuit board substantially traces a inner side wall of the lens housing.

8. The xenon flash module of claim 4 or 5 wherein the filler is one of a epoxy resin and a adhesive rubber.

9. The xenon flash module of any one of the preceding claims further comprising a slim electrolytic capacitor.

10. The xenon flash module of any one of the preceding claims wherein the xenon lamp comprises a disc-like electrode.

1 1. The xenon flash module of any one of the preceding claims wherein an external surface of the lens window is substantially flush with an external surface of the image capturing device such that the lens window does not protrude out from the image capturing device.