WO2013113548A1

WO2013113548A1 - Led tube

Info

Publication number: WO2013113548A1
Application number: PCT/EP2013/050659
Authority: WO
Inventors: Yuanyuan He; Yaojun Feng; Zesheng Ye; Xuewei Dai
Original assignee: Osram Gmbh
Priority date: 2012-01-30
Filing date: 2013-01-15
Publication date: 2013-08-08
Also published as: CN103225749A

Abstract

Provided is a LED tube comprising a PCB (2), light emitting diodes (LEDs) serving as light source and a LED driver (6) fixedly disposed on the PCB with the LEDs. The LED tube further comprises a switchable optical cover (5), in which the PCB together with the LEDs and the LED driver that are disposed on the PCB are mounted. The switchable optical cover (5) allows the LED tube to switch between a fully transparent condition and a partially transparent condition. Therefore, a user is allowed to choose conveniently between a high efficiency LED tube and a glareless LED tube according to actual requirements, and does not need to store and replace the entire LED tube.

Description

LED TUBE

BACKGROUND

Field of the Invention

[0001] The present invention relates to a LED tube, and more particular to a LED tube with a switchable optical cover.

Description of the Related Art

[0002] LED tubes are also known as light tubes, or fluores- cent tubes. The LED tube uses a light emitting diode (LED) as its light source. Compared with a conventional fluorescent tube, the LED tube results in higher light efficiency, lower energy consumption, longer life and more environmental friendly. Moreover, the LED tube does not require any ballast and starter. Thus, it is easy to achieve modularized manufac^¬ ture and installation. Therefore, LED tubes become popular and are widely used in every aspect of production and life.

[0003] A conventional LED tube includes a housing and a LED unit disposed inside the housing. The LED unit is consisted of a PCB, and LEDs and a LED driver that are mounted on the PCB . Since LED is characterized in pointolite, high power, narrow beam output, etc.. Thus, one single LED has problems such as low luminance, etc., in lighting applications. There^¬ fore, the LED unit is typically in a form of a LED integrated circuit unit where a plurality of LEDs are mounted on the PCB in array. The housing is constituted by lamp caps, a lamp base and a light transmissive optical cover. The LED unit is mounted on the lamp base in such a way that the lumination region thereof faces directly toward the optical cover and light emitted from the LED passes through the optical cover to illuminate. To reduce transmission loss, the LED tube is typically shielded, at a backlight side, by opaque material. An example of this type of LED tube is shown in a partial section view in Figure 1A.

[0004] Figures IB and 1C schematically show optical covers of conventional LED tube. Generally, according to transmission character of optical cover, optical covers of LED tubes may be divided into two types, one of which is a highly transmis- sive optical cover (see Figure IB) , the other is a optical cover that is diffusive and light softly (see Figure 1C) . To facilitate describing, the highly transmissive optical cover is referred to as a "fully transparent" optical cover, and the optical cover giving soft light is referred to as a "par^¬ tially transparent" optical cover. The two different optical covers have different optical performance. The fully trans- parent optical cover has an advantage of high light transmit- tance and thus allows the overall lighting system to have a high light efficiency. However, since the LED has a extremely high luminous intensity per unit area, people will feel very dazzling and glaring when looking straight into an LED bead, which causes uncomfortable feelings in people. However, the partially transparent optical cover performs just the oppo^¬ site. That is, the partially transparent optical cover has diffusive effect, intense light directed onto the optical cover will diffuse to spread rays to the outside space more softly and more homogeneously. Therefore, there is no unfa^¬ vorable dazzling in such an optical cover. However, the partially transparent optical cover has lower light transmit- tance, and thus the overall light system will has a lower light efficiency. [0005] It is usually difficult for a user to make choice when purchasing a LED tube. If a fully transparent optical cover with high light efficiency is selected, the user has to en^¬ dure the unfavorable dazzling caused thereby. On the con- trary, if a partially transparent optical cover is selected, it means that high luminance of the tube will be sacrificed. While, when the product is in use, there is no choice but to replace a new tube so as to make a transfer between a high efficiency LED tube and a glareless LED tube.

SUMMARY

[0006] In view of this, an object of the present invention is to provide an improved LED tube, which overcomes the above stated shortcomings.

[0007] To achieve the above object, the present invention provides an LED tube including a PCB; light emitting diodes (LEDs) fixedly disposed on the PCB and serving as light sources; and a LED driver fixedly disposed on the PCB, char- acterized in that, the LED tube further includes a switchable optical cover, in which the PCB together with the LEDs and the LED driver that are disposed on the PCB are mounted, wherein the switchable optical cover is configured to allow the LED tube to switch between a fully transparent condition and a partially transparent condition.

[0008] In one embodiment of the present invention, the switchable optical cover comprises a fully transparent half and a partially transparent half, in the fully transparent condition, the fully transparent half is located in a light emitting path of the LED, and in the partially transparent condition, the partially transparent half is located in the light emitting path of the LED.

[0009] Preferably, the full transparent half and the par^¬ tially transparent half of the switchable optical cover are symmetrically disposed.

[0010] In one embodiment of the present invention, the PCB is disposed in the switchable optical cover such that it is ro- tatable relative to the switchable cover.

[0011] In one embodiment of the present invention, the LED tube further includes an engagement means that allows the PCB and the switchable optical cover to switch between a fixed position and a rotatable position.

[0012] In one embodiment of the present invention, the en^¬ gagement means comprises a first engagement portion fixed to the PCB and a second engagement portion fixed to the

switchable optical cover, in the fixed position, the first engagement portion and the second engagement portion are en^¬ gaged with each other, in the rotatable position, the first engagement portion and the second engagement portion are dis^¬ engaged to allow the switchable optical cover and the PCB to rotate relative to each other.

[0013] In one embodiment of the present invention, one of the first engagement portion and the second engagement portion has a convex structure, and the other has a concave struc^¬ ture . [0014] Preferably, the first engagement portion and/or the second engagement portion is elastically deformable.

[0015] Preferably, the switchable optical cover is cylindri^¬ cal in shape.

[0016] Preferably, the switchable optical cover is made of plastic. Further, the switchable optical cover may be formed by molding or extrusion.

[0017] The LED tube of the present invention allows the user to make a switch between a high efficiency LED tube and a glareless LED tube according to actual requirements without storing and replacing the entire LED tube. Preferred embodi^¬ ments of the present invention provide switchable structures for the optical cover of the LED tube. When a intense illumi^¬ nation with high light efficiency is required, the user may conveniently switch the optical cover of the LED tube, such that the fully transparent optical cover is located in the light emitting path. While, when glare is critical and the user is willing to sacrifice light efficiency, the user may choose to switch the optical cover of the LED tube, such that the partially transparent half giving soft light is located in the light emitting path. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and further objects and advantages of em^¬ bodiments of the present invention will be further described in conjunction with specific embodiments and with reference to accompanying drawings. The present invention will become more apparent from reading the description below. In the drawings, like or corresponding technical features or compo^¬ nents are indicated by like or corresponding reference num^¬ bers, and wherein:

[0019] Figure 1A is a schematic, partial section view of a prior LED tube.

[0020] Figures IB and 1C are schematic cross-sectional views of LED tubes having a fully transparent optical cover and a partially transparent optical cover, respectively, in the prior art. [0021] Figure 2 is a schematic cross-sectional view of a LED tube with a switchable optical cover according to a preferred embodiment of the present invention.

[0022] Figure 3 is a detail view of an engagement means of the LED tube according to the preferred embodiment of the present invention.

[0023] Figure 4 shows a transfer process of the switchable optical cover structure according to the preferred embodiment of the present invention from a partially transparent optical cover to a fully transparent optical cover.

[0024] Figure 5 shows a transfer process of the switchable optical cover structure according to the preferred embodiment of the present invention from a fully transparent optical cover to a partially transparent optical cover.

DETAILED DESCRIPTION

[0025] Hereinafter, several specific embodiments of the pre- sent invention are described. These specific embodiments only serve to illustrate the present invention and should not be construed as limitations thereto.

[0026] The LED tube according to the present invention in^¬ cludes a housing and a LED unit fixed inside the housing through fixing means. The housing includes lamp caps and an optical cover, and optionally also includes a lamp base. The LED unit includes a PCB, a plurality of LEDs serving as light source, and a LED driver for driving the LEDs, the LEDs and the LED driver are disposed on the PCB. The lamp caps are de- tachably fixed to the opposing ends of the optical cover and are electrically connected with the PCB. When being used, the LED tube is supplied with electric current at both ends through the lamp caps, then the LEDs are driven to emit light by the LED driver. The light emitting area of the LEDs are directly face toward the optical cover and a backlight side is shielded by opaque material to reduce transmission loss. Thus, light emitted from the LEDs passes through the optical cover to illuminate.

[0027] The optical cover is configured to be able to switch between a fully transparent optical cover and a partially transparent optical cover. Therefore, the LED tube may be ad- justed to switch between a fully transparent condition and a partially transparent condition without storing and replacing the entire LED tube for the switch.

[0028] In some other embodiments of the present invention, the switchable optical cover includes a fully transparent half and a partially transparent half. When intense illumina^¬ tion with high light efficiency is required, a user may ad^¬ just the LED tube so than the fully transparent half of the switchable optical cover is located in a light emitting path of the LED. While, when glare is critical and the user is willing to sacrifice light efficiency, the user may adjust the LED tube so than the partially transparent half of the switchable optical cover is located in the light emitting path . [0029] The fully transparent half and the partially transpar^¬ ent half of the switchable optical cover may be integrally formed. Therefore, the switch between the fully transparent half and the partially transparent half in the light emitting path of the LED is achieved through moving the switchable op- tical cover relative to the LED unit inside. However, it is conceived that the fully transparent half and the partially transparent half may be separately formed, so as to actuate the respective cover portion to implement the switch as re^¬ quired. For example, the fully transparent half and the par- tially transparent half may be telescopicly disposed within the housing of the tube, when intense illumination with high light efficiency is required, the fully transparent half may be manually or electrically extended out into the light emit^¬ ting path of the LED, meanwhile the partially transparent half is retracted, and vice versa. It is also conceived that the fully transparent half may be fixed in the light emitting path of the LED. Once soft light output is required, a diffu^¬ sive material layer may be overlapped onto the fully trans- parent half, and thus the switch is achieved. As may be un^¬ derstood by persons skilled in the art, the embodiments de^¬ scribed herein is only illustrative, the switchable optical cover of the present invention does not limited thereto, but can also be implemented in many other embodiments. All these embodiments should also be construed as within the scope of the present invention.

[0030] Figure 2 shows a LED tube 1 according to a preferred embodiment of the present invention in a sectional view.

Wherein, the switchable optical cover 5 has a cylindrical shape and is constituted by a fully transparent half 5a and a partially transparent half 5b. The LEDs 3 and the LED driver 6 are fixedly disposed on the PCB 2 and then mounted inside the switchable optical cover 5 together through a fixing means (not shown) . According to preferred embodiment of the present invention, the PCB is mounted within the switchable optical cover 5 such that the switchable optical cover 5 and the PCB 2 may be rotatable relative to each other in a circumferential direction of the switchable optical cover 5. Therefore, the fully transparent half 5a and the partially transparent half are alternately located in the light emit^¬ ting path of the LED 3. In this way, the switch of the LED tube 1 between the fully transparent condition and the par^¬ tially transparent condition is achieved. However, it is con- ceived that the switchable optical cover 5 may be detachably mounted or telescopicly mounted, in order to place the desir^¬ able one of the fully transparent half 5a and the partially transparent half 5b into the light emitting path of the LED 3. [0031] In the preferred embodiment shown in Figure 2, the LED tube 1 further includes an engagement means 4 which is con^¬ figured to allow the PCB (i.e., the LED3) and the switchable optical cover to switch between a fixed position and a ro- tatable position. The engagement means 4 may include a first engagement portion 4a fixed to the PCB 2 and a second engage^¬ ment portion 4b fixed to the switchable optical cover 5. When the first engagement portion 4a and the second engagement portion 4b are engaged with each other, the PCB 2 and the switchable optical cover 5 are in the fixed position and can^¬ not rotate relative to each other. When a force is applied to disengage the first engagement portion 4a and the second en^¬ gagement portion 4b from one another, then the switchable op- tical cover 5 and the PCB 2 are allowed to rotate relative to each other. Therefore, through providing the engagement means 4, accurately positioning of the switchable optical cover 5 relative to the PCB 2 and thus the LEDs 3 may be achieved.

[0032] In some embodiments, the first engagement portion 4a and the second engagement portion 4b are made of elastomer and are form-fitted with each other. When a rotating force is applied to the switchable optical cover 5 or the PCB 2, the first engagement portion 4a and/or the second engagement por^¬ tion 4b are elastically deformed and disengaged, such that the switchable optical cover 5 and the PCB 2 are allowed to rotate relative to each other. In other embodiments, the first engagement portion 4a and the second engagement portion 4b may be frictionally or magnetically engaged. When a rotat^¬ ing force is applied to the switchable optical cover 5 or the PCB 2 to overcome the frictional or magnetic force between the first engagement portion 4a and the second engagement portion 4b, the first engagement portion 4a is disengaged from the second engagement portion 4b and thus allow the switchable optical cover 5 and the PCB 2 to rotate relative to each other. It is also conceived that the first engagement portion 4a and the second engagement portion 4b may be de- tachably engaged with or fixed to each other through screwing and the like. From the above description of particular em- bodiments, it will be appreciated by persons skilled in the art, the engagement means 4 of the present invention may be implemented in many other forms without departing from the scope of the present invention. [0033] In the preferred embodiment shown in Figure 2, the first engagement portion 4a has a concave structure, and the second engagement portion 4b has a mating convex structure to the concave structure of the first engagement portion 4a. The first engagement portion 4a or the second engagement portion 4b is elastically deformable. As will be understood, the pre^¬ sent invention is not limited this particular structure. For, example, it is possible that the first engagement portion 4a has a convex structure and the second engagement portion 4b has a concave structure. In addition, it is also possible that the first engagement portion 4a and the second engage^¬ ment portion 4b are designed to have mating structures and shapes in other forms. It is conceived that the first engage^¬ ment portion 4a and the second engagement portion 4b may be form-locked and are rigid, for example, pinned with each other, so as to restrict the relative rotating between the PCB 2 and the switchable optical cover 5. In this case, the first engagement portion 4a and the second engagement portion 4b may be unlocked through releasing the fixing means and moving the switchable optical cover in a longitudinal direc- tion of the tube, and thus relative rotating between the PCB 2 and the switchable optical cover 5 is allowed.

[0034] According to preferred embodiments of the present in^¬ vention, the switchable optical cover 5 of the present inven^¬ tion is a plastic optical cover. Since LED light source does not emit infrared rays and ultraviolet rays, it is not neces^¬ sary to use a high thermal resistant optical cover made of glass. In anther aspect, a plastic optical cover has advan^¬ tages of lower cost, lower weight and unbreakability over a glass optical cover. However, a glass transparent cover may also be used by the present invention.

[0035] The cylindrical switchable optical cover 5 of the pre^¬ sent invention may be integrally formed by molding or extru- sion. Then, surface treatment is performed to a half 5b of the optical cover that is to be made partially transparent. For example, the half 5b of the optical cover may undergo frosting processing. Alternatively, it is possible to provide the molding surface of half of the die for the optical cover with frosting and arises of nets, or the respective half of the extrusion head for the optical cover may be designed to have a corrugated shape, or the surface of a calendar roll for the optical cover is made sandblasting effect. As a re^¬ sult, the surface of a formed plastic product exhibits corre- sponding configuration. When rays irradiate on such a surface with complicated pattern of ridges and valleys, diffusive ef^¬ fect occurs. In this way, the switchable optical cover 5 may be integrally formed or one-shot formed. It is conceived, the switchable optical cover 5 of the present invention may be formed by overlaying a material layer with diffusive effect on a half of an ordinary cylindrical transparent optical cover. However, the fully transparent half 5a and the par^¬ tially transparent half 5b of the switchable optical cover 5 may also separately formed and are then bond together. That is, the present invention is not limited in material and processing method of the optical cover.

[0036] Next, the process in which the switchable optical cover 5 is transferred between the fully transparent half and the partially transparent half will be described with refer- ence to Figures 4 and 5.

[0037] As shown in Figure 4, if glare issue is more concerned about, a consumer may prefer to use the partially transparent half 5b of the optical cover as the cover through which the rays from the LEDs 3 will transmit. Once an improved light efficiency of the entire lighting system is required to give an intense illumination regardless of the glare issue, the first engagement portion 4a or the second engagement portion 4b may preferably be elastically deformed to become disen^¬ gaged through applying a rotating force to the switchable op^¬ tical cover 5. Then, the switchable optical cover 5 may be rotated relative to the PCB 2 and thus the LEDs 3 to the po- sition where the rays of the LEDs transmit through the half

5a of the optical cover having high light transmittance . Con^¬ sequently, the light efficiency of the lighting system is im^¬ proved and a high brightness illumination is obtained.

[0038] On the contrary, if a high light efficiency is more important for the consumer, he/she may prefer to use the fully transparent half 5a of the optical cover as the cover through which the rays from the LEDs 3 will transmit. When it is not necessary to provide a dazzling intense illumination, through applying a rotating force to the switchable optical cover 5 by the consumer, the first engagement portion 4a or the second engagement portion 4b may be elastically deformed to become disengaged. Then, the switchable optical cover 5 may be rotated relative to the PCB 2 and thus the LEDs 3 to the position where the rays of the LEDs transmit through the partially transparent half 5b of the optical cover. Conse^¬ quently, the rays transmit through the half 5b of the optical cover having diffusive effect and illuminate homogeneously and softly.

[0039] With the present invention, it is possible for the consumer to conveniently select to use a high light effi^¬ ciency LED tube or a glareless LED tube, without storing and replacing the entire LED tube for this purpose. In addition, the switchable structure for the LED tube according to pre- ferred embodiments of the present invention is simple and easy to operate and substantially adds no manufacturing cost to single LED tube.

[0040] Although preferred embodiments of the present inven- tion have been described herein in detail. It shall be under^¬ stood that the present invention does not limited to the spe^¬ cific structures that are shown and described herein in de^¬ tail. Other modifications and variants can be made by a per^¬ son skilled in the art without deviating from the essential and scope of the present invention. For example, for the pur^¬ pose of explanation, the preferred embodiments of the present invention is described taking a typical round tubular LED tube, such as a T8 tube, for example. Accordingly, the switchable optical cover 5 is designed to have a cylindrical shape and the two halves 5a, 5b of the optical cover are de^¬ signed to have symmetric semi-circular cross sections. How^¬ ever, as will be understood, depending on actual form and de^¬ sign of the LED tube, the switchable optical cover 5 may be provided in other suitable forms, and also the halves 5a, 5b of the optical cover may be asymmetric with each other. All these modifications and variants are within the protection scope of the present invention.

Claims

1. A LED tube comprising

a PCB;

light emitting diodes (LEDs) fixedly disposed on the PCB and serving as light sources; and

a LED driver fixedly disposed on the PCB,

characterized in that, the LED tube further comprises a switchable optical cover, in which the PCB together with the LEDs and the LED driver that are disposed on the PCB are mounted,

wherein the switchable optical cover is configured to al^¬ low the LED tube to switch between a fully transparent condi^¬ tion and a partially transparent condition.

2. The LED tube according to claim 1, characterized in that, the switchable optical cover comprises a fully trans^¬ parent half and a partially transparent half, in the fully transparent condition, the fully transparent half is located in a light emitting path of the LED, and in the partially transparent condition, the partially transparent half is lo^¬ cated in the light emitting path of the LED.

3. The LED tube according to claim 2, characterized in that, the full transparent half and the partially transparent half of the switchable optical cover are symmetrically dis^¬ posed .

4. The LED tube according to claim 1, characterized in that, the PCB is disposed in the switchable optical cover such that it is rotatable relative to the switchable cover.

5. The LED tube according to claim 4, characterized in that, further comprises an engagement means that allows the PCB and the switchable optical cover to switch between a fixed position and a rotatable position.

6. The LED tube according to claim 5, characterized in that, the engagement means comprises a first engagement por^¬ tion fixed to the PCB and a second engagement portion fixed to the switchable optical cover, in the fixed position, the first engagement portion and the second engagement portion are engaged with each other, in the rotatable position, the first engagement portion and the second engagement portion are disengaged to allow the switchable optical cover and the PCB to rotate relative to each other.

7. The LED tube according to claim 6, characterized in that, one of the first engagement portion and the second en^¬ gagement portion has a convex structure, and the other has a concave structure.

8. The LED tube according to claim 6, characterized in that, the first engagement portion and/or the second engage^¬ ment portion is elastically deformable.

9. The LED tube according to any one of claims 1-8, characterized in that, the switchable optical cover is cylin^¬ drical in shape.

10. The LED tube according to any one of claims 1-9, characterized in that, the switchable optical cover is made of plastic.

11. The LED tube according to claim 10, characterized in that, the switchable optical cover is formed by molding.

12. The LED tube according to claim 10, characterized in that, the switchable optical cover is formed by Extrusion.