JP2011090970A - Led emergency lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost AC driven LED emergency lighting device necessitating none of a specialized AC circuit, a constant current circuit, a charging circuit, a power failure detecting circuit, and a change-over switch or the like. <P>SOLUTION: The LED emergency lighting device is composed of a plurality of serially connected LEDs L1-Ln and serially connected lithium ion batteries LB1-LBn and current limiting resistances R1-Rn, connected in parallel with all of the LEDs or an arbitrary number of LEDs out of the LEDs. The plurality of the LEDs are arranged on a current outputting part of a diode bridge 200. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lighting device using LEDs (light emitting diodes).

  Due to the many potential advantages of LEDs as a light source compared to incandescent bulbs, LEDs will soon be an alternative for most applications that currently use incandescent bulbs. LEDs have been developed to increase the amount of light, and some currently available LEDs provide the same amount of illumination as conventional 60 watt bulbs. Also, LEDs are relatively efficient, and recent LED prototypes show a white light efficiency of 131 lumens per watt while consuming only 100V, 20mA of power.

  Furthermore, improvements have been made to the color of light emitted by the LED, and the LED has significant advantages over incandescent bulbs in terms of lifetime. This is because some LEDs can withstand about 100,000 hours. Although the current cost of introducing LED lighting is quite high, the lifetime cost of LED lighting will definitely be competitive with incandescent lighting.

  One problem with LED lighting relates to electrical circuitry for supplying power to the LEDs. Unlike incandescent bulbs that operate regardless of the polarity of the applied current, LEDs only emit light when the voltage source is used in positive polarity, i.e., when the LED is forward biased. Since the LED is a diode, the voltage applied across the LED is logarithmic to the current. Since power is generally considered to be proportional to current, the LED power source should be a constant current source that maintains constant power.

  In low power applications that require only a small number of LEDs, such as cellular phones, the required direct current (DC) power can be easily supplied by a battery source. However, the need for a DC source can cause problems in applications that require large amounts of light output, such as building lighting. In particular, there is a huge facility cost for emergency UPS power supplies.

One current practical example is converting AC (alternating current) power into a DC constant current using a linear or switching power supply. However, such power sources require large scale components such as transformers, inductances, capacitors, and the like. As a result, the LED may be excluded as an illumination option used in a limited space. In addition, the complexity of converting from AC to DC inherently results in power loss.
In addition, if DC power is transmitted over long distances, the complexity and cost of the system will generally increase. For these reasons, as an application of the conventional technology, a method of alternating-current driving LED lighting directly from an AC power source has been announced (Patent Document 1, Patent Document 2, and Patent Document 3).

In the case of an emergency lighting device, a secondary battery is required, and a dedicated lighting device may be installed using special indoor wiring using an emergency power source (UPS) installed in the entire building. Has been done. As a lighting device, a cold cathode fluorescent lamp is used. However, it is difficult to reduce the size because a dedicated power supply device is required in each lighting device. A technique for reducing the size of an emergency lighting device by using an LED instead of the cold cathode fluorescent lamp is disclosed (Patent Document 4).
JP 2008-263203 A JP 2006-221940 A JP 2007-140771 A JP 2009-158214 A

Although the LED emergency lighting device disclosed in Patent Document 4 has reduced the size of the device, the emergency lighting device still includes a power supply circuit, a constant current circuit, a charging circuit, a power failure detection circuit, a changeover switch, and the like. There is a problem that it is necessary and expensive in terms of cost.

The present invention has been made in view of the above problems, and a plurality of LEDs connected in series, and a series-connected lithium ion battery and current connected in parallel to all or any number of LEDs among the LEDs. An object of the present invention is to provide an emergency lighting device composed of a limiting resistor.

  According to the present invention, an LED emergency lighting device can be realized without the need for a special power supply circuit, constant current circuit, charging circuit, power failure detection circuit, and changeover switch required for each lighting device in the prior art. Thus, the size can be further reduced, and a significant reduction in cost can be realized. In addition, since the secondary battery is built in the lighting device of the present invention, an emergency lighting device can be realized only with a commercial AC power supply, and power supply from a common emergency power supply (UPS) as a whole building becomes unnecessary, In the case of a building that is not equipped with an emergency power supply (UPS), there is an effect that it can be easily installed even in the case of a building that is equipped with a dedicated indoor wiring that is not prepared in advance.

FIG. 1 shows the configuration of an LED emergency lighting device 100 of the present invention. The diode bridge 200, light emitting diodes L1, L2,... Ln, current limiting resistors R1, R2,..., Rn, lithium ion batteries LB1, LB2,. The power is supplied from the AC power source 500. RL1 and RL2 are protective current limiting resistors, each of about 100 ohms. However, in order to simplify the calculation, the voltage drop at this resistor is ignored.

FIG. 2 shows a lithium ion battery LBi and a current limiting resistor Ri connected in parallel with each LED Li as one block, and a diode bridge diode is shown by Db. FIG. 3 is an explanatory view of the operation. is there.
In FIG. 2, If is a forward current of the LED, Ibat is a charging current of the lithium ion battery, and Vin is a potential applied to the LED.

Since n LEDs are connected in series to the external commercial AC power supply 500, the voltage Vin applied to each LED Li is V as the commercial AC voltage.

(Formula 1) Vin = | V · sinωt / n |

This is shown in FIG.

In FIG. 3A, Vf is an applied voltage when the LED is emitting light, and Vbat is a voltage of a lithium ion battery.
The Vf of the white LED is generally 3.5V in terms of TYP value and 4.0V in terms of MAX value, and the voltage is within the operating range of 3.0V to 4.2V of the lithium ion battery. Vth is the forward threshold voltage of the LED, and the operating voltage Vbat of the lithium ion battery is selected to be slightly higher than Vth.

FIG. 3B shows If when there is no lithium ion battery. If the applied voltage Vin to the LED is less than or equal to the threshold voltage Vth of the LED, If is zero, If Vin rises and the LED is lit, If begins to flow, a substantially constant current flows. The forward voltage of the LED at that time is Vf, which is between Vth and V / n. When Vin decreases to Vth, the LED is turned off, and If becomes zero again.

FIG. 3C shows If when there is a lithium ion battery. When Vin rises and exceeds Vth, the LED is lit, and If is the same as FIG. 3B. When Vin is Vth or less, current is supplied from the lithium ion battery, and the LED is lit. Since the current value is substantially equal to If in FIG. 3B, If maintains a substantially constant current value over the entire interval.

FIG. 3D shows the charge / discharge current Ibat of the lithium ion value. When Vf exceeds Vbat, the lithium ion battery is charged until it reaches Vf, and If + Ibat is supplied from the commercial power source. When it becomes equivalent to Vf, charging stops (Ibat = 0). Since charging can be regulated by the MAX value of Vf, there is no possibility of overcharging with Vbat exceeding 4.2V.

Since Vbat is selected to be higher than the forward threshold voltage Vth of the LED, when Vin is lower than Vbat, the discharge current (Ibat <0) from the battery flows to the LED and becomes If, and the LED is turned on. . Originally, the LED is turned on / off when the Vin level changes, but the LED can be turned on even when Vin is low (Vf or less) by inserting a battery. In actual use, flicker due to blinking of the LED is prevented or reduced, and it is effective in securing the total luminous flux.

When the commercial power supply fails, Ibat <0 is set as If, the LED is turned on, and it works as emergency lighting until Vbat becomes Vth or less. In an emergency lighting device, it is not always necessary to ensure the same illuminance as when power is supplied at the time of a commercial power failure. By appropriately setting the number of lithium ion batteries to be connected in parallel and connecting them in parallel to the required number of LEDs, good. In FIG. 1, the LED of L2 indicates a situation where lithium ion batteries are not connected in parallel.

In addition, the time when Vbat of the lithium ion battery becomes Vth or less due to discharge can be expected to be several hours or more. On the contrary, the emergency lighting device of the present invention is lit for several hours even when the power switch is turned off. Therefore, by providing a battery on / off switch Si as shown in FIG. Lighting control as a device can also be made possible.

In actual use, it seems that it is necessary to attach / detach the lithium ion battery. Therefore, in the emergency lighting device of the present invention, as shown in FIG. 5A, a battery attaching / detaching slot 620 having contact pins 621 is provided, and the contact shown in FIG. 5B is provided. As shown in FIG. 6, the lithium ion battery pack 630 having the terminal 631 is inserted into the battery attaching / detaching slot 620 so that the battery can be replaced.

The LED emergency lighting device 100 of the present invention has a so-called diode bridge 200 between the power source 500 and the lighting LED in order to enable driving with an AC power source. It goes without saying that even if a DC power supply is used instead, it functions as a lighting device.

It is a block diagram of the LED emergency lighting apparatus of this invention. Basic block consisting of LED, lithium-ion battery and current limiting resistor The current voltage graph for description of the operating principle of LED lighting. Basic block with lighting control switch Battery attachment / detachment slot for attaching / detaching lithium ion batteries Lithium ion battery pack State of wearing lithium-ion battery pack

100: LED emergency lighting device 200 of the present invention: Diode bridge 500: Commercial AC power supply Db: Bridge diode If: LED forward current Ibat: Battery charging current L1, L2,... Ln: LED
LB1, LB2, .LBi, LBn: Lithium ion batteries R1, R2, .Ri, .Rn: Current limiting resistors RL1, RL2: Current limiting resistors Vin: LED input potential

Claims (4)

An illumination device using LEDs,
A plurality of LEDs connected in series;
To all or any number of the LEDs,
An LED lighting device comprising a series-connected lithium ion battery and a current limiting resistor connected in parallel. The LED lighting device according to claim 1,
An LED lighting apparatus comprising: a plurality of LEDs arranged in a rectification output section of a diode bridge. The LED illumination device according to claim 1, further comprising a socket to which a lithium ion battery can be attached and detached. An LED-type lighting device equipped with an emergency light function on / off switch and having a function of detecting whether AC or DC from the original power transmission side is cut off or whether it is extinguished by human investigation.