LED flame effect lighting device

There is provided a lighting device comprising a plurality of light emitting diodes (LEDs) that simulate a flame. The device comprises a circuit board having a plurality of through-holes extending between two opposing faces of the circuit board, and wherein at least some of the LEDs are mounted inside the through-holes so they are visible from both faces of the circuit board.

This application claims the benefit of GB 1710069.4 filed 23 Jun. 2017.

DESCRIPTION

The present invention relates to a lighting device comprising a plurality of Light Emitting Diodes (LEDs) that simulate a flame; for example, a flaming torch.

BACKGROUND OF THE INVENTION

It is known to produce lighting devices that incorporate LEDs which simulate a flame. For an effective simulation, the lighting device needs to produce a flame-like light which looks like a flame regardless of which direction the lighting device is viewed from.

The German Utility Model DE 202015107152U describes an LED simulation candle where a bottom circuit board is attached horizontally to a base, and three circuit boards with LEDs are vertically soldered to the bottom circuit board at 120 degrees to one another so the flame effect can be seen from any direction.

However, this construction is complex and requires manufacture of multiple circuit boards in order to provide a flame effect that can be seen from all viewing angles.

It is therefore an object of the invention to improve upon known LED simulation flames.

SUMMARY OF THE INVENTION

According to the invention, there is provided a lighting device comprising a plurality of LEDs that simulate a flame. The device comprises a circuit board having a plurality of through-holes extending between two opposing faces of the circuit board, and at least some of the LEDs are mounted inside the through holes so they are visible from faces of the circuit board.

By mounting the LEDs in through-holes, or in other words holes that go all the way through the circuit board, the LEDs become visible on both sides (faces) of the circuit board, without needing to provide multiple circuit boards.

Preferably, a diffusion envelope is mounted on an end cap of the lighting device, and envelops the circuit board so that it diffuses light from the LEDs. Then, the LEDs do not look like point sources of light from outside the envelope and the flame effect is created more effectively.

The plurality of through-holes preferably comprise a line of at least three through-holes in which LEDs are mounted along an axis of symmetry of the circuit board, for example along a central vertical axis of the circuit board, so that the center of the flame is well defined.

An LED driver for powering the LEDs may be mounted on the same circuit board as the LEDs to avoid the need for any additional circuit boards, further reducing the cost of manufacturing the lighting device. The LED driver preferably switches or modulates the powers sent to the LEDs to simulate a flickering flame, for example a candle flame. The plurality of LEDs may comprise at least two groups of LEDs, and the LED driver may switch or modulate the powers sent to the groups of LEDs to light the groups of LEDs at different times to one another.

To help improve the flame effect when the circuit board is viewed from a peripheral side edge of the circuit board, some of the LEDs may be mounted at the peripheral side, and so are visible from the peripheral side and from both faces of the circuit board. The two opposing faces may each be in the shape of a flame, wherein the peripheral side extends all around the flame shape. The LEDs mounted to the peripheral side are preferably spaced around at least 180 degrees of the circuit board periphery, so the flame shape can be discerned when the LEDs are lit. The flame shape may be a candle flame shape, and a candle flame shape is generally understood to be a roughly rectangular shape with a height at least twice its width and optionally narrowed towards the top of the candle flame shape.

The lighting device of the first embodiment has an end cap in the form of a base10comprising a circular outer housing12and an inner platform14inside the housing12. The base also comprises a power supply cable18, which terminates in a plug19. The power supply cable18is connected to a battery (not shown) inside the platform14. Optionally, the battery may be rechargeable, and if so then the base10may have a charging jack for receiving electrical power to recharge the battery. Alternatively, the battery could be omitted entirely, and the power supply cable may be connected to a jack socket in the base for receiving electrical power from an external source.

The lighting device also comprises a circuit board20, which is in the shape of a candle flame. The circuit board shape is roughly rectangular with a height greater than twice its width, and the width of the rectangular shape is narrowed at the top29of the circuit board. In this embodiment, the circuit board is a printed circuit board (PCB).

The circuit board20has first and second faces21aand21b, which are opposite to one another, and in parallel, separated by the thickness of the circuit board. The circuit board has a peripheral side22extending all the way around the circuit board and adjoining from the first face to the second face.

The first face21ahas a socket23for receiving the plug19of the power supply from the base. The circuit board includes conductive tracks (not shown for clarity) that carry the power from the socket23to an LED driver24on the first face21a.

The circuit board20also has five through-holes26which extend all the way through the thickness of the circuit board and its faces. The through-holes26are arranged centrally along the circuit board in a vertical line, and each one of the through-holes has a single corresponding LED27inside of it. The LEDs27are electrically connected to the LED driver24via conductive tracks (not shown for clarity) of the circuit board20. The LEDs27are visible from both faces21aand21bof the circuit board, via the through-holes26.

The circuit board20also has eleven LEDs25spaced apart from one another around the peripheral side22. The LEDs25are also electrically connected to the LED driver24via conductive tracks (not shown for clarity) of the circuit board20. The LEDs25are also visible from both faces21aand21bof the circuit board, since they extend beyond the peripheral edge22, and so are not obscured from view by the circuit board20. The LEDs25and27together form a flame shape when they are lit, and the flame shape can be seen from substantially all viewing angles.

The inner platform14of the base has two clips16, and a lower part28of the peripheral side22of the circuit board fits into the clips16to retain the circuit board20to the base10.

The circular outer housing12has a stepped portion13running around the upper circumference of the housing12, and a bottom edge33of a diffuser30is a friction fit over the top edge of the outer housing12, and rests on the stepped portion13. The diffuser30envelopes the circuit board20inside the diffuser, and light from the LEDs is diffused by the diffuser so that the LEDs do not look like point sources of light when viewed from outside the diffuser.

In use, the LED driver24sends power to the LEDs25,27to light them and so to simulate a flame. The LEDs are split into groups and the LED driver switches the various groups of LEDs on and off at differing times to one another to simulate a flickering flame torch or candle. Optionally, a Universal Serial Bus (USB) jack could be provided on the base10to provide power and/or control, for example to specify how the LED lights should be controlled by the LED driver. The USB jack may power the power supply cable18directly, or the USB jack may be used to recharge a battery for powering the power supply cable18.

The lighting device of the second embodiment shown inFIG. 2has an end cap in the form of a top100. The top100is substantially the same as the base10of the first embodiment, except for that it further includes a solar panel110on its top surface. In the second embodiment, the solar panel110is used to recharge the battery inside the platform of the top100.

A circuit board120, which is similar to the circuit board20of the first embodiment, is held by the top100using clips on a platform of the top100, in the same manner as the clips16of the platform14hold the circuit board20of the first embodiment. The circuit board120differs from the circuit board20in that the circuit board120has the LED's arranged the opposite way up compared to the circuit board20, so that the flame still appears the right way up even although the circuit board orientation is inverted in the second embodiment. For example, the LED127adjacent the socket and LED driver of the circuit board simulates the tip of the flame in the second embodiment, whereas the LED27aat an opposite end of the circuit board from the socket and LED driver simulates the tip of the flame in the first embodiment.

A diffuser130connects to the top100and envelopes the circuit board120within it, similar to the diffuser30of the first embodiment.

Many other variations of the described embodiments falling within the scope of the appended claims will be apparent to those skilled in the art.