Beam shaping for spiral LED filament systems

Abstract

The present disclosure relates to a light emitting diode (LED) filament system 770 comprising an LED filament 100 and a controller 771. The LED filament includes a support 120 configured in the shape of a spiral formed by continuous loops 250. The LED filament further includes a plurality of LEDs 110 arranged in a linear array on one side of the support. The LEDs are arranged in sections 140a-f along the support, each section having a position along the spiral-shaped support. The controller is configured to control power supply to sections or groups of sections of the LED filament. The controller is adapted to control sections based on the position of the sections or groups of sections based on the position of the sections in the group.

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of solid-state lighting. In particular, the present disclosure relates to a light-emitting (LED) filament system comprising a spiral-shaped LED filament including a plurality of LEDs arranged in sections and a controller. [Background technology]

[0002] Incandescent lamps are rapidly being replaced by light-emitting diode (LED)-based lighting solutions. Solid-state lighting devices can offer many advantages over incandescent, fluorescent, and gas discharge-based lighting devices. For example, solid-state lighting devices can provide increased operating life, reduced power consumption, and higher efficacy. Solid-state lighting devices, such as LEDs, are being adopted in a wide range of lighting applications.

[0003] LED-based lighting devices are constantly being developed and may offer new solutions that extend far beyond what is possible with conventional light sources. Summary of the Invention [Problem to be solved by the invention]

[0004] One general objective of the present disclosure is to provide even more versatile LED-based lighting solutions. Specifically, it is desired to be able to provide an LED filament system that allows for customizable light distribution.

[0005] It is therefore an object of the present invention to achieve at least some of the above-mentioned goals and to provide improved LED-based lighting. [Means for solving the problem]

[0006] This and other objects are achieved by an LED filament system as defined in the appended claims. Further embodiments are defined by the dependent claims.

[0007] According to a first aspect of the present disclosure, a light-emitting diode (LED) filament system is provided. The LED filament system includes an LED filament and a controller. The LED filament includes a support configured in the shape of a spiral formed by continuous loops. A plurality of LEDs are arranged in a linear array on a side of the support. Specifically, the LEDs are arranged in sections, each section having a position along the spiral-shaped support. The controller is configured to control power supply to the LED filament, to sections, or to groups of sections of the LED filament. The controller is further adapted to control the section based on the position of the section, or the group of sections based on the position of the section of the group.

[0008] The support forms a spiral shape by winding in a continuous curve around a central axis. A loop is formed by winding a portion of the support 360 degrees around the central axis. A first end portion (start portion) of the loop may be separated from a second end portion (end portion) of the loop in a direction along the central axis, i.e., the first end portion and second end portion are located at two different positions (heights) along the length of the spiral.

[0009] The LEDs may be arranged in a linear array on one side of the support. For example, the LEDs may be arranged in a single row along the support. Alternatively, the LEDs may be arranged in two or more rows along the support. When the LEDs are arranged in multiple rows along the support, the rows may be at least substantially parallel. The LEDs may be arranged at a substantially constant pitch (the distance between consecutive LEDs).

[0010] It will be appreciated that the LEDs may be disposed on several sides of the support, for example, the LED filament may include a second plurality of LEDs disposed on a second, opposite side of the support.

[0011] Lighting devices with spiral-shaped LED filaments are highly valued for their decorative appearance. A spiral-shaped LED filament that includes individually controllable sections (i.e., sections whose power supply is individually controllable by a controller) or sections that can be controlled as a group can provide a customizable light distribution.

[0012] According to one embodiment, the LEDs of a section may be controllable by a controller to emit light with variable intensity.

[0013] For example, the controller may control a section to provide a first intensity I1 and another section to provide a second intensity I2. The first intensity I1 may be at least twice the second intensity I2 (I1>2I2). Specifically, the first intensity I1 may be at least three times the second intensity I2 (I1>3I2). More specifically, the first intensity I1 may be at least four times the second intensity I2 (I1>4I2).

[0014] Many different types of LEDs may be used to provide sections with variable intensities. For example, the plurality of LEDs may include LEDs configured to emit blue light. Alternatively, or in addition, the plurality of LEDs may include LEDs configured to emit ultraviolet (UV) light. For the LED filament to provide white light, the LED may be covered with an encapsulant that includes a wavelength-converting material, such as a luminescent material. Alternatively, the LEDs may be individually covered with the wavelength-converting material.

[0015] The wavelength-converting material may absorb at least a portion of the light emitted by the LED and emit light having a different wavelength. The type of LED and wavelength-converting material may be selected so that the LED filament provides light having a desired color or color temperature. The encapsulant covering at least the LED may include a light-scattering material. The light-scattering material may include, for example, particles of barium sulfate (BaSO), aluminum oxide (III) (AlO), and / or titanium dioxide (TiO).

[0016] An LED filament with sections that can be controlled to emit light of variable intensity can create the possibility of a beam sweep, a lighting effect in which successive sections are illuminated with higher intensities, which can give the appearance of a light beam moving around the LED filament.

[0017] According to some embodiments, the LEDs of the sections may be controllable by a controller to emit light having variable colors.

[0018] Various types of LEDs may be used to provide sections with variable colors. For example, the plurality of LEDs may include red, green, and blue LEDs. Light from the red, green, and blue LEDs may be combined at different intensities to form a wide variety of colors. Alternatively, the plurality of LEDs may include LEDs that provide white light of different color temperatures. For example, the plurality of LEDs may include a first plurality of LEDs configured to provide white light having a first warmer white hue (e.g., light having a lower correlated color temperature) and a second plurality of LEDs configured to provide white light having a second cooler white hue (e.g., light having a higher correlated color temperature).

[0019] The power supply to the different types of LEDs may be controllable so that the color and / or color temperature of the light emitted by the sections can be adapted. Such embodiments may provide LED filaments that allow for different color patterns. For example, such embodiments may allow for color gradients (gradual transitions between colors) in the light provided by the LED filaments.

[0020] According to some embodiments, the position of a section may be defined as a height and an angle. The height of a section (i.e., the position of the section along the height of the helical support) may relate to the distance from the end portion of the LED filament along the central axis (or longitudinal axis) of the helical shape. The angle of a section (i.e., the position of the section along the circumference of the helical support) may relate to the position of the section along the loop relative to the start point of the loop.

[0021] The angle of a section may be the angle formed between a line drawn from the beginning of the loop to the central axis and a line drawn from the beginning of the section to the central axis.

[0022] According to some embodiments, the spiral loop may include N sections. The number of sections in the loop, N, may be in the range of 2-8.

[0023] For example, the number N of sections in the loop may be in the range of 3 to 7. More specifically, the number N may be in the range of 4 to 6.

[0024] For embodiments in which each loop includes more than one section, the light distribution of the LED filament may be controlled asymmetrically. For example, the section corresponding to one half of each loop may be illuminated with a higher intensity and / or a different color than the other half, resulting in illumination on one side of the LED filament being different from illumination on the other side. More sections in a loop may result in greater variability in the light distribution of the LED filament.

[0025] For example, in embodiments where N is at least 2, a section may be controlled (by a controller) to provide a first intensity I1 and another section may be controlled to provide a second intensity I2. The difference between the first intensity I1 and the second intensity I2 may be at least 40%.

[0026] In embodiments where N is at least 4, two sections located on opposite sides of the loop (e.g., at the front and back of the LED filament) may be controlled (by the controller) to provide a higher intensity than other sections of the loop.

[0027] In embodiments in which each loop comprises one section, the loops may be individually controllable or may be arranged in controllable groups. Such embodiments may provide different light distributions along the central axis. For example, a controller may individually control the power supply to the loops so that the intensity and / or color of one loop is different from the intensity and / or color of a different loop.

[0028] Additionally, different embodiments may include different numbers of loops. In embodiments including at least four loops, the section positioned within the loops at one end portion of the LED filament may be controlled to provide a higher intensity than the section positioned within the loops at the other end portion of the LED filament.

[0029] Controlling the LED filament so that individual sections are illuminated and turned off according to a defined pattern may be referred to as beam shaping. LED filaments may be used in conjunction with reflectors to provide beam shaping.

[0030] According to some embodiments, the sections may include at least a first set of sections and a second set of sections, and the first set of sections and the second set of sections may be arranged in a repeating manner along the support.

[0031] For example, in an embodiment including a first set of sections and a second set of sections, the sections of the first set and the sections of the second set may be arranged in alternating fashion along the support.

[0032] The first set of sections may be different from the second set of sections. The first set of sections and the second set of sections may, for example, provide light having different color temperatures.

[0033] For example, a first set of sections may have a thicker encapsulant layer than a second set of sections. The thicker encapsulant layer containing the wavelength-converting material may result in a greater portion of the light emitted by the LED being converted (i.e., absorbed by the wavelength-converting material and re-emitted at a different wavelength).

[0034] Alternatively, or in addition, the first set of sections may include a different type of wavelength converting material than the second set of sections, either covering at least the LEDs or disposed within an encapsulant that individually covers the LEDs.

[0035] As a third option, the first set of sections may include a higher concentration of wavelength converting material than the second set of sections, either covering at least the LEDs or disposed within an encapsulant that individually covers the LEDs.

[0036] Additionally, the first set of sections may include different types of LEDs than the second set of sections.

[0037] It will be understood that an embodiment including a first set of sections and a second set of sections may further include additional sets of sections, such as a third set of sections. In such embodiments, sections from different sets may be arranged in a repeated pattern along the support. For example, the sections may be arranged in a pattern where sections from the first set are followed by sections from the second set, which are then followed by sections from the third set, with the pattern repeated along the support.

[0038] According to some embodiments, each loop of the helical shaped LED filament may include the same number of sections.

[0039] According to some embodiments, each loop may include N sections. Further, the N boundaries between the N sections of a loop may be aligned with the N boundaries between the N sections of consecutive loops along the height of the helical support.

[0040] In embodiments where the sections are aligned along the height of the helical support (or along the central axis of the helical shape), sophisticated patterns in the illumination of the LED filament may be achieved.

[0041] In embodiments in which each loop includes two sections, a first section and a second section, the first sections of the loops may be aligned (i.e., positioned on top of each other in a spiral configuration of sections) and the second sections of the loops may be aligned. In such embodiments, all of the first sections may be illuminated, followed by all of the second sections. When the second sections are illuminated, the first sections may be turned off. In such embodiments, the first sections may form a first set, the second sections may form a second set, and the third sections may form a third set.

[0042] In embodiments where the number of sections in each loop, N, is 3 or greater, the first sections of the loops may be aligned, the second sections of the loops may be aligned, the third sections of the loops may be aligned, etc. In such embodiments, all first sections may be illuminated for a first period, followed by all second sections for a second period (consecutive to the first period), followed by the third sections, etc. When the second sections are illuminated, the first sections may be switched off. When the third section is illuminated, the first and / or second sections may be switched off, etc.

[0043] Successive groups of aligned sections may be sequentially illuminated and turned off to produce a beam sweep.

[0044] According to some embodiments, the radius of the loops of the helix may vary along the height (ie, along the central axis) of the helical shaped support.

[0045] For example, the loops at the end portions of the LED filament may have a smaller radius than the loops located in the center of the LED filament (ie, between the end portions), thereby giving the LED filament a barrel-like shape.

[0046] Alternatively, the loops at the end portions of the LED filament may have a larger radius than the loops between the end portions, In such an embodiment, the helical shaped filament may have a generally hourglass or diabolo shape.

[0047] In a further option, the radius of the loop increases / decreases continuously from one end of the spiral to the other.

[0048] According to some embodiments, the length of the section in the loop with the smaller radius may be shorter than the length of the section in the loop with the larger radius.

[0049] For example, the lengths of the sections of different loops may be adapted so that each loop contains the same number of sections.

[0050] In embodiments where all loops have the same radius, the sections may have the same length.

[0051] According to some embodiments, each section may include at least two LEDs.

[0052] In embodiments where each section includes more than one LED (ie, at least two LEDs), the individual sections may provide a greater luminous flux.

[0053] In an individually controllable section containing only one LED, the LED is effectively individually controllable.

[0054] Alternatively, in embodiments in which the lengths of the sections may vary, some sections may include one LED, while other sections may include no more than one LED.

[0055] According to some embodiments, the LEDs of a section may be electrically connected in series.

[0056] Embodiments in which the LEDs of a section are electrically connected in series may be convenient to produce as a less complex system of electrical connections is required. Furthermore, when the LEDs within a section are connected in series, the intensity of the entire section can be controlled collectively.

[0057] Alternatively, the LEDs may be individually controllable, or different groups of LEDs within a section may be separately controllable. For example, in embodiments where a section includes LEDs that provide light having different colors, the LEDs within a section that provide the same color may be electrically connected in series. In such embodiments, the color of a section may be controlled by controlling the power supply to the different colored LEDs within the section and, therefore, the intensity emitted by the different colored LEDs within the section.

[0058] For example, within a section, some LEDs may be electrically connected in series and some LEDs may be electrically connected in parallel, and it will be appreciated that power supply to sections (within which LEDs may be connected in series and / or parallel) may be controlled by a controller.

[0059] In embodiments where the LEDs within a section are individually controllable, the lighting pattern may also be adapted within each section.

[0060] According to some embodiments, the controller may be configured to control the supply of power to a first section or group of first sections differently from the supply of power to a second section or group of second sections.

[0061] According to some embodiments, the controller may be configured to control the powering of the sections of the LED filament such that the luminous flux of the LED filament is substantially constant over time.

[0062] In such embodiments, the LED filaments may provide the same amount of illumination over time, but the direction and / or pattern of illumination may change. Such lighting effects may be particularly desirable for event lighting.

[0063] It will be understood that the luminous flux may not be constant each time the LED filament system is used. Rather, by "constant over time" it is meant constant over a particular period of time. For example, the amount of luminous flux may be a setting provided by a controller.

[0064] Alternatively, or in addition, similar settings may be available for color: the controller may be configured to provide a constant total amount of light having different wavelengths (colors), and the direction in which light having a particular color is emitted may vary.

[0065] According to some embodiments, the controller may be configured to control the energization of sections or groups of sections of the LED filament based on a desired light emission direction.

[0066] For example, the controller may control the powering of sections or groups of sections so that sections that emit light in a desired direction are turned on and other sections are turned off. The light emission direction of a section may depend on the position of the section. For example, in an embodiment in which the LEDs are positioned on a side of the support facing away from the central axis of the spiral shape, the LEDs may emit light in a direction away from the central axis.

[0067] For example, the controller may be adapted to control / correspond to sections of the LED filament based on the height and angle of the section. In such an embodiment, all height sections within a particular angular range, i.e., sections located at the same position along the circumference of the spiral-shaped support but at different heights, may be illuminated with a particular lighting pattern.

[0068] According to a second aspect of the present disclosure, there is provided a lighting device. The lighting device may comprise an LED filament system as described with reference to any embodiment of the second aspect. The lighting device may further comprise an at least partially light-transmitting envelope. The envelope may at least partially surround at least an LED filament of the LED filament system. The lighting device may further comprise a base onto which the envelope may be mounted. The base may further be adapted for connection to a luminaire socket.

[0069] The lighting device may be an LED filament lamp. Light emitted by the LED of the LED filament may be referred to as LED light. Light emitted by the LED that is absorbed by a wavelength conversion material and re-emitted at a different wavelength may be referred to as converted light. Therefore, the light provided by the LED filament (LED filament light) may include a combination of LED light and / or converted light. The at least partially light-transmitting envelope is adapted to transmit the LED filament light. Therefore, the LED filament lamp may include LED filament light or provide LED filament lamp light as a result.

[0070] The lighting device may have a longitudinal axis, which may for example extend substantially perpendicular to the surface of the base.

[0071] The central axis of the helical shaped LED filament may be substantially parallel to the longitudinal axis of the lighting device.

[0072] Alternatively, the central axis of the helical shaped LED filament may be substantially perpendicular to the longitudinal axis of the lighting device.

[0073] It should be noted that other embodiments may be envisioned that use all possible combinations of the features recited in the above embodiments, and therefore the present disclosure also relates to all possible combinations of the features referred to herein. [Brief explanation of the drawings]

[0074] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings, in which: [Figure 1] 1A-1C show top and side views of an LED filament, according to some embodiments. [Figure 2] 1A-1C show a side view of an LED filament configured in a spiral shape formed by a continuous loop and a top view of the loop, according to some embodiments. [Figure 3] 1A-1C show a side view of an LED filament configured in a spiral shape with alternating first and second sections and a top view of a loop of the LED filament, according to some embodiments. [Figure 4] 1A-1C show side views of an LED filament configured in a spiral shape where the radius of the loops varies along the height of the spiral, and a side view of the LED filament in a stretched state, according to some embodiments. [Figure 5] 1 illustrates a section of an LED filament where the LEDs are electrically connected in series, according to some embodiments. [Figure 6] 1 shows a section of an LED filament with each type of LED electrically connected in series, according to some embodiments. [Figure 7] FIG. 1 is a schematic diagram of an LED filament system, according to some embodiments. [Figure 8] 1 is a schematic diagram of a lighting device according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0075] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which presently preferred embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for completeness and comprehensiveness, and will fully convey the scope of the invention to those skilled in the art.

[0076] Referring to FIG. 1, an LED filament 100 according to some embodiments is illustrated.

[0077] Figure 1 shows a top view of an LED filament 100 and a side view of the same LED filament 100. In Figure 1, the LED filament 100 is stretched into a straight configuration for illustrative purposes.

[0078] The LED filament 100 includes a support 120. The support 120 may be flexible so that it can be wound into a spiral shape. However, a rigid support that can be shaped into a spiral may also be used. A plurality of LEDs 110 are arranged in a linear array on the side of the support 120. Specifically, the LEDs 110 are arranged in a single row along the support 120. The LEDs 110 are arranged in sections 140a-f. The sections 140a-f may be individually controllable, and power supplied to the LEDs 110 in each section 140a-f may be controlled by a controller. In other words, one of the sections 140a-f may be controlled separately from the other sections, so that, for example, the power supplied to the LEDs in a first section 140a may be different from the power supplied to the LEDs in a second section 140b.

[0079] Furthermore, as shown in the side view, the LED filament 100 includes an encapsulant 130. The encapsulant 130 covers the plurality of LEDs 120 and the side of the support 120 on which the LEDs 110 are disposed. The encapsulant 130 may include a wavelength converting material and / or a light scattering material. In embodiments in which the encapsulant 130 includes a wavelength converting material, the wavelength converting material may itself have a light scattering effect.

[0080] The color of light emitted by the LED filament 100 may be affected by the type of LED 110 and the type of encapsulant 120 used in the LED filament.

[0081] For example, the LED filament 100 may be configured to emit white light having a single color temperature, and the intensities of the different sections 140a-f may be controlled to achieve this. In such an embodiment, the LED 110 may be an LED adapted to emit blue and / or UV light, and such an LED may provide high efficiency. The encapsulant 120 may include wavelength-converting materials, such as yellow and red phosphors. The light converted by the phosphors may combine with unconverted light from the LED to form white light. Alternatively, the LED 110 may include a combination of a blue LED and a red LED. In such an embodiment, the wavelength-converting material may partially convert the blue light to form white light.

[0082] Alternatively, the LED filament 100 may be configured to emit white light having a variable color temperature and / or variable intensity. In such an embodiment, the LED 110 may include at least two different types of LEDs. A first type of LED may be configured to emit white light of a first color temperature, and a second type of LED may be configured to emit white light having a second color temperature, different from the first color temperature.

[0083] Additionally, to provide intensity and / or color control, the LEDs 110 may include a combination of red, green, and blue LEDs, and in such embodiments, the encapsulant may include a light-scattering material.

[0084] It will be understood that an LED filament generally comprises a plurality of light emitting diodes (LEDs) arranged in a linear array, providing LED filament light. Preferably, the LED filament has a length LF and a width W, with LF>5W. The LED filament may be configured in a non-linear configuration, such as a curved configuration, a 2D / 3D helix, or a swirl. Preferably, the LEDs are disposed on an elongated support, such as a substrate, which may be rigid (e.g., made from a polymer, glass, quartz, metal, or sapphire) or flexible (e.g., made from a polymer, or metal, e.g., a film or foil).

[0085] When the support includes a first major surface and an opposite second major surface, the LED is disposed on at least one of these surfaces. The support may be reflective or may be light-transmitting, such as translucent or transparent. In particular, the support may be semi-reflective.

[0086] The LED filament may include an encapsulant at least partially covering at least some of the LEDs. The encapsulant may also at least partially cover at least one of the first major surface or the second major surface. The encapsulant may be a polymeric material, such as silicone, which may be flexible. Furthermore, the LEDs may be configured to emit LED light, e.g., of different colors or spectrums. The encapsulant may include a luminescent material configured to at least partially convert the LED light into converted light. The luminescent material may be a phosphor, such as an inorganic phosphor and / or a quantum dot or quantum rod.

[0087] An LED filament may include multiple sub-filaments.

[0088] Referring to FIG. 2, an LED filament 200 configured in the shape of a spiral is illustrated, according to some embodiments.

[0089] FIG. 2 shows a diagram of an LED filament 200 configured in a spiral shape. The LED filament 200 may be equivalent to the LED filament 100 described with reference to FIG. 1, except configured in a different shape. The LED filament 200 may include a rigid or flexible support, so long as it can be shaped as a spiral. The spiral extends along a central axis A. For illustrative purposes, the LED filament 200 is shown as having a uniform cylindrical shape. This appearance may be achieved by embedding the LED and support within an encapsulant such that the encapsulant covers all sides of the support.

[0090] The LED filament 200 may be configured such that the surface of the support on which the LEDs are disposed faces away from the central axis A. Furthermore, the LEDs may be disposed such that the light-emitting surface of each LED faces away from the central axis A. Therefore, most of the light emitted by the LED filament 200 may be directed away from the LED filament 200.

[0091] In embodiments in which the support is (partially) light-transmitting, the LED filament 200 may be configured such that 60-90% of the LED filament light is emitted in a direction away from the central axis A. For example, the LED filament 200 may be configured such that the surface of the support on which the LEDs are disposed and / or the light-emitting surface of each LED faces away from the central axis A. Alternatively, or in addition, a semi-reflective support may be used.

[0092] The LED filament 200 is wound into a continuous loop 250 having a substantially constant radius r about a central axis A. A top view of the loop 250 is also shown. The loop 250 is formed by a portion of the LED filament 200 that is wound 360 degrees around the central axis A.

[0093] The spiral-shaped LED filament has a height H that corresponds to the distance along the central axis from a first end portion or first end 201 of the LED filament 200 to a second end portion or second end 202 (opposite the first end 201) of the LED filament 200.

[0094] Also shown is one of the sections 240. The location of the section 240 may be defined or described by the height h of the section 240 and the angle θ of the section 240. The height h of the section is the distance along the central axis from the first end portion 201 to the section 240. The angle θ of the section 240 is the angle formed between a semi-line drawn from the beginning 251 of the loop 250 to the central axis A and a semi-line drawn from the beginning of the section 240 to the central axis A.

[0095] Referring to FIG. 3, an LED filament including a first set of sections and a second set of sections is described, according to some embodiments.

[0096] FIG. 3 shows a side view of the LED filament 300 and a plan view of one of the loops 350 of the LED filament 300. The LED filament 300 may be similar to the LED filament 200 described with reference to FIG. 2, except that the LED filament 300 includes a first set of sections 340a and 340b and a second set of sections 341a and 341b. The first set of sections 340a and 340b and the second set of sections 341a and 341b are alternately arranged along the LED filament 300. Specifically, each loop 350 includes two sections 340a and 340b of the first set and two sections 341a and 341b of the second set. Furthermore, the sections of different loops are aligned in a direction along the central axis of the spiral-shaped LED filament 300. For example, one of the sections 340a of the first set of loop 350 is aligned with a section of the first set of each of the other loops. In the illustration, the first set of sections 340a of loop 350 is aligned with the first set of sections of each of the other loops.

[0097] The LED filament 300 may be controlled to perform a beam sweep. Such a lighting effect may be achieved by sequentially illuminating sections arranged within a series of angular ranges. For example, the first section 340a in each loop may be illuminated first. The other sections 341a, 340b, and 341b may be either turned off or illuminated at a lower intensity than the first section 340a. In this first case, most of the light emitted by the LED filament 300 will be directed toward the first section 340a, for example, within a range of 0 to 90 degrees.

[0098] Second, a second adjacent section 341a in each loop may be illuminated. The other sections 340a, 340b, and 341b may again either be turned off or illuminated with a lower intensity than the second section 341a. Most of the light emitted by the LED filament 300 will now be directed toward the second section 341a, for example, within a range of 90 to 180 degrees.

[0099] A third section 340b in each loop, adjacent to the second section 341a, may then be illuminated while the other sections are turned off or dimmed. Most of the light emitted by the LED filament 300 will then be directed toward the third section 340b, for example, within a range of 180 to 270 degrees.

[0100] Finally, a fourth section 341b in each loop, adjacent to the third section 340b, may be illuminated while the other sections are turned off or dimmed (i.e., illuminated at a lower intensity). Most of the light emitted by the LED filament 300 will then be directed toward the fourth section 341b, for example, within a range of 270 to 360 degrees.

[0101] If this process is performed repeatedly, the beam of light emitted by the LED filament may be perceived as sweeping around the LED filament 300. During this process, the controller may be adapted to control the illumination of the sections such that the luminous flux of the LED filament 300 remains substantially constant over time as the beam sweeps around the LED filament.

[0102] The first set of sections 340a and 340b may be further configured to emit light having a different color temperature than the second set of sections 341a and 341b. In such an embodiment, the color temperature of the light emitted by the LED filament may be adjusted by matching the intensity of the light emitted by the first set of sections 340a and 340b and the second set of sections 341a and 341b.

[0103] Referring to FIG. 4, an LED filament 400 is illustrated in which the radius of the loop varies along the height of the LED filament, according to some embodiments.

[0104] 4 shows a side view of an LED filament 400 having a helical shape and a side view of the same LED filament 400 in a stretched configuration. The LED filament 400 may be similar to the LED filament 200 described with reference to FIG. 2, except that the radius r of the loop varies along the height H of the LED filament 400.

[0105] The LED filament 400 is wound around a central axis A. The radius r of the loop increases along a height h from the first end portion 401 to the central portion 403 of the LED filament 400. The radius r of the loop decreases again along a height H from the central portion 403 to the second end portion 402 of the LED filament 400.

[0106] The stretched version of the LED filament 400 shows different sections 441, 442, 443 of the LED filament 400. Near the end portions 401, 402, the section 441 has a shorter length. The length of the sections increases towards the central portion 403 of the LED filament. Specifically, each loop of the LED filament 400 includes two sections of equal length.

[0107] Referring to FIG. 5, a section 541 of an LED filament 500 in which LEDs 112 are electrically connected in series is illustrated, according to some embodiments.

[0108] 5 is a diagram of a portion of an LED filament 500. The LED filament 500 may be equivalent to any of the LED filaments 100-400 described with reference to the previous figures.

[0109] 5 shows a section 541 of an LED filament 500 that includes four LEDs 112. An LED 111 from the left section of section 541 and an LED 113 from the right section of section 541 are also shown. The LEDs 112 are electrically connected in series via a first electrical connector 562. Therefore, the intensity of the LEDs 112 in section 541 may be simultaneously controlled by controlling the power supply of the LEDs 112 via the first electrical connector 561. Furthermore, the LEDs 111, 113 from adjacent sections are connected in series via a second electrical connector 562.

[0110] Referring to FIG. 6, a section 640 of an LED filament including a red LED 610a, a green LED 610b, and a blue LED 610c is illustrated, according to some embodiments.

[0111] 6 shows a section 640 of an LED filament, which may be similar to any of the LED filaments 100-400 described with reference to FIGS. 1-4, except that it includes red, green, and blue LEDs.

[0112] Within section 640, two red LEDs 610a, two green LEDs 610b, and two blue LEDs 610c are arranged in a single row on substrate 120. The two red LEDs 610a are electrically connected in series via a first electrical connector 660a. The two green LEDs 610b are electrically connected in series via a second electrical connector 660b. The two blue LEDs 610c are electrically connected in series via a third electrical connector 660c. Connecting LEDs of the same type (color) in series may allow the intensities of the LEDs to be controlled simultaneously. Therefore, the power supply of the red LEDs 610a, green LEDs 610b, and blue LEDs 610c may be controlled separately. By controlling the power supply of the LEDs, the intensity of the light emitted by the LEDs may be controlled. By controlling the intensity ratio between LEDs of different types (colors), the color of the combined light emitted by section 641 may be controlled.

[0113] Referring to FIG. 7, an LED filament system according to some embodiments is described.

[0114] 7 shows an LED filament system 770 comprising an LED filament 700 and a controller 771. The LED filament 700 may be equivalent to any of the LED filaments previously described with reference to the previous figures. The controller 771 is connected to the LED filament 700 by an electrical connection 772.

[0115] Each loop of the spiral-shaped LED filament 700 includes a first section 740 and a second section 741. The first sections 740 of different loops are aligned along the height of the LED filament 700, and the second sections 741 of different loops are aligned along the height of the LED filament. A controller 771 is configured to control the power supply to the sections 740, 741. In the figure, the controller 771 controls the first section 740 to be illuminated and the second section 741 to be turned off (not illuminated). As a result, the light emitted by the LED filament is mostly distributed on one side of the LED filament (e.g., within a range of 0 to 180 degrees).

[0116] The controller 771 may first control all (aligned) first sections 741 to be illuminated. Then, the controller 771 may control all second sections 742 to be illuminated. While the second sections 742 are illuminated, the first sections 741 may be switched off. This control pattern may be repeated.

[0117] The first section 741 may form a first set of sections, and the second section 742 may form a second set of sections.

[0118] Referring to FIG. 8, a lighting device 880 according to some embodiments is illustrated.

[0119] 8 is a side view of a lighting device 880 according to some embodiments. The lighting device 880 comprises an LED filament system 870, which may be equivalent to the LED filament system 770 described with reference to FIG. 7. The lighting device further comprises an at least partially light-transmitting envelope 870. The LED filament 800 of the LED filament system 870 is disposed within the envelope 881. In other words, the envelope 881 surrounds the LED filament 800.

[0120] The lighting device further comprises a base 882 onto which the envelope 881 is mounted. In this embodiment, a controller 871 of the LED filament system 870 is located on the base 882 and within the envelope 881. In other embodiments, the controller 871 may be located within the base 882. An electrical connector 872 connects the LED filament 800 to the controller 871.

[0121] The base 882 is adapted to be connected to a light fixture socket, specifically, the base 882 is adapted to be connected to an Edison-type socket.

[0122] A holding structure 883 is also mounted on the base 882 to hold the LED filament 800 in place within the lighting device 880. The helical shaped LED filament 800 is oriented with its central axis parallel to the longitudinal axis of the lighting device 880.

[0123] Those skilled in the art will appreciate that the present invention is in no way limited to the preferred embodiments described above, but rather many modifications and variations are possible within the scope of the appended claims.

[0124] Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements, or can be used in various combinations with or without the other features and elements.

[0125] Furthermore, 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, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

Claims

1. a support configured in the shape of a spiral formed by successive loops; a plurality of LEDs arranged in a linear array on one side of the support, the LEDs being arranged in sections along the support, each section having a position along the spiral-shaped support; an LED filament comprising: a controller configured to control power supply to sections or groups of sections of the LED filament, Sections based on their location, or adapted to control a group of sections based on the position of the section of the group. In the controller, the position of a section is defined by a height and an angle, the height relating to the distance from an end portion of the LED filament to the section along a central axis of the spiral shape, and the angle relating to the position of the section along the loop relative to a start point of the loop; each loop of the LED filament includes N sections, the sections being separated by boundaries that are aligned with the boundaries between the sections of successive loops along the height of the spiral-shaped support; controller, An LED filament system comprising:

2. 10. The LED filament system of claim 1, wherein the LEDs of the section are controllable by the controller to emit light having variable intensities.

3. 3. An LED filament system according to claim 1 or 2, wherein the LEDs of the sections are controllable by the controller to emit light having variable colors.

4. 4. An LED filament system according to claim 1, wherein the spiral loop comprises N sections, the number N being in the range of 2 to 8.

5. 5. An LED filament system according to claim 1, wherein the sections include at least a first set of sections and a second set of sections, the first set of sections and the second set of sections being arranged repeatedly along the support.

6. 6. An LED filament system according to claim 1, wherein the radius of the loops of the spiral varies along the height of the spiral.

7. An LED filament system as described in claim 6, wherein the length of a section within a loop having a first radius is shorter than the length of a section within a loop having a second radius greater than the first radius.

8. 8. An LED filament system according to claim 1, wherein each section comprises at least two LEDs.

9. 9. An LED filament according to claim 1, wherein the LEDs of a section are electrically connected in series.

10. 10. An LED filament system according to any one of claims 1 to 9, wherein the controller is configured to control power supply to a first section or group of first sections differently from power supply to a second section or group of second sections.

11. 11. An LED filament system according to any one of claims 1 to 10, wherein the controller is configured to control the power supply of the section or group of sections of the LED filament such that the luminous flux of the LED filament is substantially constant over time.

12. 12. An LED filament system according to any one of claims 1 to 11, wherein the controller is configured to control the power supply of the sections or groups of sections of the LED filament based on a desired light emission direction, such that sections emitting light in a desired direction are turned on and other sections are turned off.

13. An LED filament system according to any one of claims 1 to 12; an at least partially optically transparent envelope at least partially surrounding at least the LED filament of the LED filament system; a base onto which the envelope is mounted, the base being adapted for connection with a lighting fixture socket; A lighting device comprising:

Images