GB2212994A

GB2212994A - Lamp operating circuit

Info

Publication number: GB2212994A
Application number: GB8727974A
Authority: GB
Inventors: Kazumi Masaki
Original assignee: HAYASHIBARA KEN
Current assignee: HAYASHIBARA KEN
Priority date: 1987-11-30
Filing date: 1987-11-30
Publication date: 1989-08-02
Anticipated expiration: 2007-11-30
Also published as: GB2212994B; GB8727974D0

Abstract

To obtain a brilliant light which has a spectral distribution close to that of sun light, an incandescent lamp W is operated at a voltage exceeding its nominal rating eg. at a voltage which 101 to 140% of its rated voltage. The lamp W may be connected to an A.C. source via a step-up autotransformer T, or a 12 volt lamp W may be connected to a 100 volt supply via a step-down transformer T having a secondary winding with 12, 13, 14 and 15 volt tape (Fig 6). A negative temperature coefficient thermistor Th, or a triac circuit (Fig 4), may be connected in series with the lamp to suppress surge currents on initial turn on. A phase controlled triac arrangement may be used to prevent over current during operation of the lamp (Figs 3,4). <IMAGE>

Description

LAMP-STARTING DEVICE The present invention relates to a lamp-starting device, specifically, to a device which can supply to a lamp with a voltage exceeding the rating to effect a brilliant illumination.

As shown in FIG.7 with the broken line, the light obtained by operating a lamp at its rating gives a spectral distribution generally with a peak at a wave length of about 1,000 nanometers. Since the light is less than sunlight in spectral component ranging from 400 to 800 nanometers, generally called "the visible region", and looks more redish than it really is. Due to these, the light is hard on the eye when used as illuminant for hours.

The present inventor investigated various means that attain an illumination close to sun light. As the result, the present inventor found that a brilliant light having a spectral distribution with a peak at 1,000 nanometers as shown in FIG.7 with the solid line is attained by operating a lamp with a voltage exceeding the rating, as well as that such light is suitable for illuminant.

More particularly, the present invention relates to a lamp-starting device, characterized in that an ac voltage is supplied by way of a voltage elevating means to a lamp so that that is illuminated with an ac voltage exceeding the rating.

Embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: FIG.1 is the circuit of an embodiment according to the invention.

FIG.2 is the circuit of an embodiment according to the invention, wherein an autotransformer and a resistor with a negative temperature coefficient are used in combination.

FIGs.3 and 4 are the circuit of an embodiment according to the invention, wherein a current-limiting means is provided.

FIG.5 is illustrative of an embodiment according to the invention, wherein a surge-limiting means is provided.

FIG.6 is the circuit of an embodiment according to the invention, wherein a head lamp for automobile is used as illuminant.

FIG.7 is illustrative of spectral distributions obtained by energizing a lamp with its rated voltage or a voltage exceeding the rating.

Throughout the accompanying drawings, symbol T designates transformer; DCR, bidirectional triode thyristor; R, resistor; C, capacitor; D, diode; Z, voltage regulating diode; W, lamp; S, switch; and Th, resistor having a negative temperature coefficient.

The present invention will hereinafter be explained with reference to the accompanying drawings.

FIG.1 is the circuit of an embodiment according to the invention, wherein lamp W is connected to secondary winding L2 of transformer T, turn ratio of 100:1-100:40 with respect to the number of turns on primary winding ml, while one end of primary winding L1 is connected to one end of secondary winding L2 so that ac 100 volts can be supplied to primary winding L1.

The voltage to be supplied to lamp W is determined with respect to the required quantity of light and lifespan of lamp W, generally, about 101-140%, desirably, 110-130% of the rating.

When in this embodiment power switch S is turned on, ac 100 volts is superposed on the voltage across secondary winding L2, i.e. 1-40 volts, and lamp W receives the total voltage. Thus, an illumination with a spectral distribution as shown in FIG.7 with the solid line can be attained.

FIG.2 is the circuit of another embodiment according to the invention, wherein autotransformer T is used as the voltage elevating means, while lamp W is connected by way of resistor Th with a negative temperature coefficient to the ends of the winding tapped into windings L1 and L2 at tap A so that ac 100 volts can be supplied between winding L1.

Resistor Th is to prevent surges that may arise immediately after switch-on of power switch S.

In this embodiment, by setting the turn ratio of L to L1 + L2 to about 100:101-100:140, desirably, 100:110100:130, an illumination with a spectral distribution as shown in FIG.7 with the solid line can be attained.

FIG.3 is the circuit of still another embodiment according to the invention, wherein autotransformer T1 is used similarly as in FIG.2 so that lamp W can receive a voltage exceeding its rating.

In this embodiment, lamp W is connected in series to the main current path of bidirectional triode thyristor DCR, while the conduction is controlled with a phase shifting circuit consisting of center-tapped secondary winding L2 of transformer T2 to be connected to ac 100 volts, resistor R5 and capacitor C2. The phase shifting circuit compares a voltage across resistor R2 with standard voltage across voltage regulating diode Z and decreases the conduction angle of bidirectional triode thyristor DCR to prevent inflow of an overpower into lamp W when a voltage across resistor R2 exceeds a prescribed level.

FIG.4 is the circuit of a further embodiment accord ing to the invention, wherein autotransformer T is used as the voltage elevating means, while inflow of an overcurrent into lamp W can be automatically prevented by bidirectional triode thyristor DCR.

In this embodiment, an elevated voltage is divided by resistors R1 and R2 at an appropriate ratio, and a voltage across resistor R2 is compared with standard voltage across voltage regulating diode Z. When a voltage across resistor R2 exceeds a prescribed level, the conduction angle of bidirectional triode thyristor DCR is narrowed to limit the power into lamp W.

FIG.5 is the circuit of a further embodiment according to the invention, wherein autotransformer T is used as the voltage elevating means, while an RC time constant circuit and a bidirectional triode thyristor are used in combination to limit surges that may arise upon switch-on of power switch S.

When resistor R1 and capacitor C in the RC time constant circuit are set, for example, respectively to 10 kiloohms and 1,000 microfarads to give a time constant of about one second, lamp W is preheated for one second after switch-on of power switch S to limit surges that may be arise when an elevated voltage is supplied from autotransformer T. Thus, the shortening of bulb life can be prevented.

FIG.6 illustrates an embodiment according to the invention, wherein a head lamp for automobile, rated voltage of 12 volts, rated power of 12 watts, is used.

In this embodiment, the voltage across lamp W can be controlled within the range of 12-15 volts by providing secondary windings L2, L3, L4 and L5 having respective turn ratio, for example, of 100:12, 100:13, 100.14 and 100:15 with respect to the number of turns on primary winding L1, and allowing power switch S1 to associate with selector switch S2 that is to switch these secondary windings.

This embodiment is characterized in that it is simple because transformer T per se limits surges arising upon switchon of power switch 51' as well as that it decreases the frequency of exchanging lamps because head lamps require a relatively long time for vaporization of their filament and endure a relatively long term use.

Furthermore, this embodiment ls characterized in that it attains an illumination with a less flicker because head lamps are larger in heat retaining ability than incandescent lamp, and that it is suitable as the illuminant for desk lamp because it can be mechanically balanced by placing transformer T at the inside bottom of the device. When the brilliance is excessively high, the bulb can be frosted or silica-coated, or combined with a lampshade or a filter both having silica-coated inside surface.

Since an illuminant rich in visible spectral component as sun light can be easily obtained with the use of the device according to the invention, it is advantageously usable, for example, in TV room, computer room, office room, and studying room.

In addition, the device of the invention can be advantageously used in treatment of human depression, as well as in illumination breeding or culture of animals and plants including "kaiware-daikon (Japanese radish in the younger stage)".

Having described specific embodiments of my bearing, it is believed obvious that modifications and variations of my invention are possible in the light of the above teaching.

Claims

CLAIMS:

1. A lamp-starting device, comprising a voltage elevating means through which an ac, source is connected to a lamp so that the lamp is illuminated with an ac voltage exceeding the rating.

2. The device of claim 1, wherein said voltage elevating means is an autotransformer.

3. The device of claim 1, wherein said lamp is an incandescent lamp.

4. The device of claim 1, wherein the lamp is supplied with an ac voltage exceeding the rating but not exceeding 1407 of the rating.

5. The device of claim 1, wherein said lamp is a head lamp for automobile.

6. The device of claim 1, wherein said starter is used for desk lamp.

7. A lamp-starting device substantially as hereinbefore described with reference to the accompanying drawings.