MXNL05000079A - Low power lighting circuit based on leds (without rectification phase). - Google Patents

Abstract

The present circuit is useful for any configuration or arrangement emitting light obtained directly or indirectly from LEDs. The waveform of the supplying voltage signal is not limited to the sinusoidal waveform (available in most worldwide plugs having frequencies of from about 50 Hz to about 60 Hz), therefore the invention is useful for any type of wave containing positive and negative cycles useful for the rectification of the full-wave bridge by means of diodes. The main concept of the present invention is the use of the full-wave bridge rectifier by replacing traditional diodes for LEDs, which function is to provide light using an AC signal having an input frequency, the half of which is higher than that perceived by the human eye as intermittent.

Description

LOW POWER LIGHTING CIRCUIT BASED ON LEDS (WITHOUT RECTIFIER PHASE).

OBJECT OF THE INVENTION The object of the present invention is that by means of a characteristic arrangement of LEDs, in a circuit, the power consumption of the LEDs that provide the illumination can be economized, which can be of any type. The configuration of the diodes (LEDs), in a so-called "Diode Bridge" will allow the trajectory of the sine wave of the current to be followed in order to provide low power consumption and adequate illumination.

It should be considered that another objective of this invention lies in the fact that no direct current supply is required for the operation of said circuit.

BACKGROUND Currently, the energy crisis is increasingly evident worldwide. Lighting represents one of the largest sources of electricity consumption, which is why it is necessary to develop inventions that can generate light consuming little electricity. The arrangement of the LED circuit presented in this invention manages to create continuous illumination with a low electrical consumption. Several circuits based on LEDs are known, present in numerous devices, whose function is to illuminate. Traditionally, LEDs are used with direct current (DC). However, in most houses, apartments, commercial premises, etc. there is alternating current (AC). Therefore, lighting circuits based on LEDs that use AC are more practical, since they do not require converting the AC current to direct. In North America and in many other regions of the planet, there are typically sources of alternating current power of 120 V and 60 or 50 Hz frequency. The approach of this invention is to use said AC power source without the need to use a rectifying phase to convert from alternating current to direct current.

According to a patent analysis that was carried out, some characteristics were found with which this invention can be related, as well as some differences, advantages and disadvantages that exist between those that were found with the one referred to in this document. document. The following patent comparison is mentioned which could establish a relationship with the present are: The patent US 660980 called "LED interior light fixture", which coincides because it is a device that operates with low voltage, adjustable to residential sockets, in addition to including high intensity white light LEDs, in terms of differences We found that it converts available AC power to low DC voltage.

Patent US 6350041 which is called "High output radial dispersing lamp using a solid state light source", whose main coincidence lies in the fact that it is a domestic lighting device that uses a prism of light to manipulate light. Regarding the differences, we find that even when the prism of light is based on optical fiber, it also incorporates two functions (condensing and dispersing light), in addition to using laser diodes.

Another patent with which this was compared, was the US 6367949 called "Par 36 LED utility lamp", having as main resemblance that the PCB of the LEDs is separated from the power circuit and as the main difference that one of the circuits is used for illumination of alert and the other to illuminate work areas, in addition, the base of the LEDs rotates on an axis.

The number US 6203180 called "Airplane cabin lighting arrangement" whose similarity lies in the fact that the lighting is focused on a small area without dispersing the light, besides that it has low power consumption, however it does not move in desirable directions since the The device is fixed to the ceiling socket and uses the available DC power from the vehicle's network.

The US 6227679 denominated "LED light bulb" has as main coincidence the disc shape of the PCB and the orientation of the LEDs. Among its differences we find that it does not directly use AC as an energy source. Because of its plug, it can not be connected to the commercial outlet. The power circuit is located on the PCB of the LEDs.

The patent number US 6250774 is another patent whose main similarity is that it has the same lighting unit and that the color of the light of the LEDs is the same. The main difference is that the light can not be directed because the luminaire's screen is fixed, plus it requires an AC-DC converter to operate.

However, the patent US 6461019 entitled "Preferred embodiment to LED light string" is the one with the closest resemblance. The patent presents a series of configurations with LEDs that use the same principle of the present invention to achieve that the LEDs emit light using directly AC without rectifying phase, with an on-off effect but which the human eye perceives as continuous light given the intermittency frequency.

In the drafting of that patent in question, Figure 1A shows a configuration known as "half wave", where the chain of LEDs only turn on during the cycle of the same polarity of the AC source to which they are connected, thus wasting more 50% of the available energy in the source corresponding to the other half of the cycle in which the chain of LEDs is polarized in reverse. On the other hand; Figure IB shows a "full wave" configuration, which takes advantage of the two halves of the cycle. The biggest disadvantage of making strings of LEDs in series, whose sum of individual voltages fall equals half the amplitude of the source voltage, is that if a single LED of the chain fails (or is connected in reverse polarity) to the rest of the chain), the complete series will not turn on during the middle of the polarization cycle, since that chain will remain as an open circuit and no current will flow to energize the LEDs.

Another major disadvantage of these configurations is that the circuits do not have current limiting impedances, resistances are commonly used. Its main function is to limit the high non-linearity of the current against the characteristic response curve of the LEDs. The absence of these limiting elements causes damage to the LEDs reducing their useful life.

Other patents were found, however the previous ones were the ones that had the most similarities with the design proposed in this document.

BRIEF DESCRIPTION OF THE FIGURES Figure 1. Schematic representation of the different phases that are traditionally used to power an array of LEDs, from the available signal of the current socket to the input voltage for the LEDs.

Figure 2. Full-wave diode bridge. Fundamental principle of the present invention using AC signals for its operation.

Figure 3. Example of a sine-wave signal as a function of time showing the positive peak and the negative peak. Typically, the frequency of this available signal is 60Hz in America and 50Hz for Europe.

Figure 4. Example of connection of rectifier LED bridges to increase the number of LEDs. The desired number of LED bridges connected in parallel can be extended since they will all receive the same voltage. The only condition is that the power supply can supply the necessary current for all the bridges.

Figure 5. Example of connecting the rectifier LED bridges to increase the number of LEDs with the option of adding more LEDs inside each of the branches of the bridge. The connection of this modified bridge can be made with more than one connected in parallel.

DESCRIPTION OF THE INVENTION The present invention relates to lighting in general, for open surfaces, for specific localized areas, decorative, indirect or any type of lighting whose light source are light-emitting diodes. For reasons of writing the present invention, from now on they will be referred to as LEDs (Light Emitting Diode).

Other patents related to lighting using LEDs base their operation by feeding the LEDs with direct current (DC) voltages, respecting the polarity of the LEDs (do not forget that they are diodes, with the peculiar characteristic that they emit light when passing current through them). Since the type of voltage available in the majority of current sources is AC, it is necessary to reduce the voltage to an adequate level and then submit it to a rectification phase in order to convert the AC signal into DC and finally power the LEDs.

In Figure 1 you can see the different stages that are traditionally used to power the arrays of LEDs, to convert the signal from AC to DC. The socket 1 of ece a voltage signal [2] typically 120VAC or 220VAC, sine wave shape with 60Hz frequency (the frequency and voltage value may change depending on the geographical location). Since it is impossible to connect said voltage level to the array of LEDs, the first phase is to reduce the voltage to an appropriate level, typically by means of a single-phase transformer [3] to obtain a voltage [4] with the same frequency but a lower wave amplitude. The next step consists in the rectification of the wave [5], which can be carried out by different means using solid state semiconductor devices. Usually, a diode rectifier bridge is used, which can be half wave or full wave [6], this being the most common for having a better use of the input signal. Finally, we proceed to convert that curly form [6] into a constant voltage signal [8], which will be the supply voltage for the arrangement of the LEDs that are used for lighting.

The present invention reduces the steps 5 and 7 presented in Figure 1, by means of a full wave diode bridge array, but instead of using conventional diodes, the LEDs are used. That is, the diodes in this patent have a double function; the rectification of the input signal and that of being the source of illumination.

The present patent manages to obtain a lighting based on LEDs without the use of the rectifier phase to be able to power them, that is, it uses the AC voltage after reducing the voltage level to that indicated for the circuit. To achieve this, the LEDs are arranged in the form of a rectifier bridge, preferably full-wave as shown in Figure 2. From this, during the first half (or positive peak) [16] of the cycle of a signal with the A suitable voltage level like the one shown in Figure 3, will create an electric current flowing through the LED [10], through the resistor [14] and through the LED [11] to return to the negative terminal of the source [ 15], because they will be correctly polarized and will turn on after passing the threshold voltage required to turn on the LED. It should be mentioned that the voltage drop for each LED varies depending on the manufacturer and the color of the light they emit. The LEDs identified with the numbers [12] and [13] will remain in open circuit because the first half of the cycle [16] of the voltage signal has an inverse polarity for that set of diodes. In the same way, but in the opposite way the first half of the cycle, during the second half of the cycle [17], the current will flow through the LED [12], going through the resistance [14] and through the LED [13] to return to the negative terminal of the voltage source; and the set of LEDs [10] and [11] will remain off, because during this half of the cycle [17] they will behave as an open circuit due to the inverted polarity of the voltage source.

The alternation "on-off" of the two sets of LEDs will be repeated with a frequency equal to the frequency of the voltage signal with which the circuit is fed. That is, if the circuit of Figure 2 is fed with a voltage frequency of 60Hz, (voltage available in most current sockets) each set of LEDs will light 30 times per second.

For applications where more LEDs are required, the arrangement presented in Figure 2 can be extended by connecting more LED bridges in parallel, or by adding more LEDs per branch of the bridge rectifier. The present patent extends to all the possible variations of connection of the LED bridges to be used without rectifying phase (conversion of alternating current to direct current), which are fed by means of a voltage signal with "positive" and "positive" cycles. Negative "which will cause the sets of LEDs to turn on and off alternately at the same frequency as the supply voltage.

Claims (5)

CLAIMS Having sufficiently described my invention, I consider as a novelty and therefore claim as my exclusive property, what is contained in the following clauses:

1. A low-power lighting circuit for energy saving characterized by a printed circuit board (PCB or Printed Circuit Board in English) or any other means for the electrical connection between components that serves as a substrate to an array of LEDs (mounting type surface or bulb type) that does not require rectifier phase (AC-DC), which are electrically connected as a full wave rectifier bridge.

2. A low power illumination circuit for energy saving according to claim 1 characterized in that the LEDs are connected in the form of a full wave rectifier bridge (diode bridge), generalized for any type of wave containing "positive cycles" and "negative cycles" that can be used in the rectification. Typical power values are 50Hz or 60Hz.

3. A low power lighting circuit for energy saving according to claim 1, characterized in that for the complete wave rectifier bridge array, the LEDs are divided into two groups; according to the rectifier bridge connection, where the first group will light up during the "positive cycle" of the wave and for the "negative cycle" the other group of LEDs will light up. This on-off between the two groups of the LEDs will alternately be done at half the frequency of the supply voltage.

4. A low power lighting circuit for energy saving according to claim 1, characterized in that the rectifier bridge arrangement of the system using LEDs for lighting use of any type, which can be connected in any way, where the Rectifier bridges are in parallel. Within each of the branches of the bridge, only one LED or several LEDs can be found in series.

5. A lighting circuit of low power for energy saving according to claim 4, characterized in that the frequency of the input signal is such that its half is greater than the frequency that the human eye can perceive as "intermittent". The principle is that the alternating frequency on-off between the two groups of LEDs of the bridge rectifier is greater than the minimum that the human eye can perceive. The principle is that this configuration of LEDs delivers light that is "continuous" to the human eye.