JP2600712Y2 - Solar lamp - Google Patents

Abstract

A solar lamp drive circuit is arranged todelay start-up while a current is supplied to the lamp filament to warm up the filament. During operation, the back emf induced in the lamp is sampled, and if operating conditions deteriorate the current to the filament is reapplied automatically and the power supply to the lamp increased.

Description

[Detailed description of the invention]

[0001]

TECHNICAL FIELD The present invention relates to a solar lamp. The present invention particularly relates to a solar lamp driving circuit used to control a lamp driven by a solar cell.

[0002]

Such lamps are available in all forms of lighting applications,
It is used especially for exterior lighting around residential areas. The lamp is arranged to be driven by a rechargeable battery provided with solar panels so that it depends mainly or solely on receiving the charging current generated by the solar cell during daylight hours.

[0003] Generally, fluorescent tubes or lamps are used and are driven via electronic ballasts. Battery energy is used to provide a high frequency, high voltage power supply that is applied across the terminals of the lamp. The ballast consists of a polyphase transformer with a free running oscillator.

[0004]

Currently known or previously proposed solar lamps are relatively inefficient in terms of power consumption, and lamp life is limited by poor control of the power supply to the lamp. Tends to.

[0005]

According to the present invention, there is provided a battery power source including a solar cell and a battery, and a terminal of a fluorescent lamp including a step-up transformer arranged to supply high frequency power between the oscillator and the terminal. A solar lamp drive circuit connecting between the switches to control warm-up power supply to one of the filaments of the lamp;
A timer controlling the switch, configured to delay the application of main operating power from the transformer to turn on the lamp at start-up to allow the lamp filament to warm up, the timer turning on the lamp. A solar lamp drive circuit is provided that is configured to control the switch to remain closed for at least a few seconds thereafter.

[0006] The circuit may include a sampling circuit for monitoring the operating condition of the lamp configured to control the switch to turn on when the lamp operating condition degrades to a predetermined condition. The oscillator output may be configured to reduce from a high starting level to a predetermined operating level once the lamp is turned on for a few seconds.

The circuit may include a manually adjusted current regulator that changes the brightness of the lamp during use. The sampling circuit may be configured to increase the oscillator output when the lamp operating condition degrades to a predetermined condition.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lamp driving circuit according to the present invention will be described with reference to the accompanying drawings showing a circuit diagram. Referring to the drawings, a circuit composed of blocks A, B, C and D is shown. In general, block A is a battery condition detection circuit configured to control the application of power to the lamp in such a way as to prevent use of the battery if its charging is very slow. Block B is a circuit that monitors external lighting conditions thereby affecting the application of power. Block C is a main part of the lamp driving circuit, and block D is basically a charging circuit, but shows a battery and a solar panel.

To explain the circuit in more detail, block A
Includes a voltage comparator U1B having a resistor R20 connected to its output to hold its output voltage. The latch is formed by gates U3C and U3D. The output of the latch at U3C is set high by the output from block B (see below). The battery voltage sampling network consists of resistors R21 and R22, diode D11 and capacitor C11. The input threshold of the sampling network is lowered after turning on by feedback resistor R24. The master reference network consists of a resistor R23 and a light emitting diode LED1 (having a negative temperature coefficient). The diode D11 is LE
Compensating for the thermal drift of D1, capacitor C11 acts to decouple noise.

If the sampled voltage is below the master reference, the output of comparator U1B goes low, setting the latch output low. As a result, as explained below,
The output of NAND gate U3A goes high, thereby turning off the lamp. Resistor 24 acts to increase the sensitivity of the battery sampling network. The hold circuit includes diodes D4 and D7, a resistor R34, and a capacitor C3. When diode D4 is forward biased and powered from block C (see below), capacitor C3 charges completely almost instantaneously. Diode D7 is then forward biased, applying a voltage to raise the input of comparator U1B. As a result, the output of comparator U1B is held high. In other words, comparator U1B is disabled. It remains disabled until there is no more supply from block C. Capacitor C3 then discharges through resistor 34 until diode D7 is cut off, and comparator U1B is released again for normal operation. A hold circuit is provided to disable comparator U1B for approximately 0.5 seconds thereafter before the lamp stabilizes.

In block B, the circuit is configured to monitor the light intensity of the environment and turn off the lamp when the intensity is above a certain level. Voltage comparator U1A with a hysteresis loop of resistor R30 has its input connected between resistors R25 and R28. These resistors divide the output of diode LED1 to provide a smaller reference voltage for comparator U1A. The voltage across the solar cell (see block D) is proportional to the light intensity and this voltage is applied across a resistor R29 via a diode D9. Diode D9 is always forward biased unless very dark. The voltage across the resistor R29 is the comparator U1A
If it is higher than the reference voltage at, its output goes low. The capacitor C8 is connected to the resistor R until the latch circuit is reset.
Discharge gradually through 19. As a result, the output of NAND gate U3A goes high, extinguishing the ramp.

In contrast, the voltage across resistor R29 is
When below the reference voltage at the node between R5 and R28, the output of comparator U1A goes high and capacitor C8 is connected to resistor R
13 and the diode D12.
As a result, the input connected to block B goes high.
If the output of the latch circuit is also high, the NAND gate U
The output of 3A goes low, which turns on the lamp.

It is noted that the time delay provided by resistor R19 and capacitor C8 prevents the street from responding to transient lighting changes such as those caused by automobile headlights or torch lamps near the lamp. It is noted that the circuit is responsive to voltage across the solar cell and does not require or use a separate light intensity measurement device or the like. Referring to block C, gate U3B receives a start signal from block A to turn on the lamp. The start delay circuit includes a resistor R9, a capacitor C4, and a diode D2.
Consists of Typically, a 10 second startup delay is provided by the delay circuit. However, the lamp can be extinguished instantaneously by including diode D2. The retriggerable timer consists of a resistor R16 and a capacitor C5. Upon receiving the start signal, the output of inverter U2B goes low and the output of inverter U2D turns on transistor Q2. At the same time, capacitor C3 starts charging via diode D4 (see block A) and capacitor C5 charges via resistor R16. As a result, current flows through transistor Q2 and acts as a switch to turn the current on and off through one of the lamp elements to warm up the element. The output of inverter U2C now acts to inhibit the battery condition detection circuit (block A) and maximize the power that can be supplied by the lamp drive circuit. The inhibit is timed to approximately double the start-up delay so that filament current is applied through transistor Q2 while the lamp is off and lasts a sufficient time to operate at high capacity once the lamp is turned on. Can be At the end of the period, transistor Q2 is turned off,
The power supplied to the lamp is adjusted to an optimal setting below the starting setting.

A sampling network consisting of resistors R4 and R5 monitors the back EMF induced in the lamp. Low back EMF indicates that the lamp is stable in the secondary breakdown region. A high back EMF indicates that the lamp operates erratically. Inverter U2E is connected to the connection between resistors R4 and R5. The voltage at the junction corresponds to unstable lamp operation,
That is, if it increases above a predetermined threshold corresponding to a lamp operating condition that degrades to a predetermined condition, the output of inverter U2E goes low, so that the retriggerable timer and transistor Q2 are immediately turned on. Thus, the restarting state of increasing the power to the lamp and applying current to one of the lamp filaments is repeated.

Thus, the sampling network automatically attempts to maintain the lamp in a stable operating secondary destruction condition; if the lamp is allowed to operate under unstable conditions, the lamp life is significantly reduced. The lamp is basically powered by a closed loop oscillator consisting of amplifiers U1D and U1C and an inverter U2F, a MOS field effect transistor Q1 and a resistor R18. The oscillator converts the battery DC power supply to a high energy, high frequency current through the boost pulse transformer T1. Oscillation may be stopped by powering through inverter U2A and a bias network consisting of resistors R1, R10 and R6 and capacitor C2. The duty cycle is determined by the DC input level of the amplifier U1D supplied via a network consisting of the resistors R31, R32, R7 and R8 and the capacitor C6. The time constant of the oscillator is determined by a filter including the resistor R17 and the capacitor C10. Higher DC input levels or higher capacitance for capacitor C10 will result in a longer on-period or vice versa. The off-duty cycle is one volt from _{Vss of the} network including resistors R2 and R3.
/ 3V _DD is determined by the time applied to capacitor C1.

A manual switch for changing the intensity of the lamp is provided between the resistors R31. When the switch is closed, the direct input level of amplifier U1D increases. Diode D3
Is forward biased as a result of the output of inverter U2C going high, this condition applies at start-up, as described below, and when an unstable operating condition is detected,
This is three times larger than usual. An approximately 20% increase occurs when the switch is in a position to short resistor R31.

The voltage across resistor R18 is proportional to the MOS field effect transistor source current sent to the lamp by transformer T1. This is sent to a low pass filter formed by a resistor R17 and a capacitor C10 to decouple to the high frequency components of the switching current. The output of the low pass filter provides an input to amplifier U1D to maintain the ON period.

The start of operation of the oscillator is as follows:
-Once the start delay circuit and the retriggerable timer have timed out, the output of inverter U2A goes low.
The voltage across resistor R18 supplied to amplifier U1D is initially zero. The output of amplifier U1D is then 1 / 2V _DD ; the voltage across resistors R1 and R2 is equal and amplifier U1D
The output of C is low. Therefore, the output of inverter U2F is high so that MOS field effect transistor Q
Turn 1 on. Therefore, the current applied to the resistor R18 increases due to the inductance of the transformer T1. Resistance R
When the voltage across 18 is greater than the non-inverting value of amplifier U1D,
Its output goes low, capacitor C1 discharges, the output of amplifier U1C goes high, the output of inverter U2F goes low, and MOS field effect transistor Q1 turns off. The current to resistor R18 is cut off, so that the output of amplifier U1D goes high. Capacitor C1 is 1
Charge above the non-inverting input level of amplifier U1C until it goes to / 3V _DD , so that the output of amplifier U1C goes low.
Therefore, the MOS field effect transistor is turned on again, and the period is such that the non-inverting input level of the amplifier U1C is 2 / 3V
Repeated until going up to _DD . Oscillator is approximately 24-33K
It is provided to reach stable oscillation at Hz.

MOS field effect transistors are used to ensure fast switching times for the power applied to the lamp. To ensure fast switching, the supply to the inverter U2F is separated from the battery voltage by a diode D6. At the beginning of the oscillation, the diode D
6 is forward-biased and the voltage applied to inverter U2F is 0.
6 volts smaller. However, the capacitor C7 is gradually charged by the back electromotive force induced in the transformer T1 via the diode D5 and the resistor R11. As a result, inverter U2
The voltage applied to F is approximately 2 volts higher than the voltage applied to amplifier U1C. MOS field effect transistor Q
Higher V _DD levels applied to 1 tend to have faster response times, thus improving the efficiency of operation with high frequency pulse transformers.

It can be seen that high frequency spikes, which are generated when the lamp is operated during the particularly early stages after starting and which occur during the back EMF, are used to charge the capacitor C7 to improve work efficiency. In block D, Schottky diode D8 allows solar cell BT2 to charge battery BT1 with minimal loss due to its forward voltage drop characteristics. Diode D8 prevents battery discharge to the photodetector strength circuit of block B.

Resistors R14 and R15, diode D10
And an external charging circuit formed by zener diode ZD1 allows the lamp to be recharged from an external power adapter. The resistors R14 and R15 limit the charging current,
Zener diode ZD1 protects the battery from overcharging. Diode D10 protects the battery from discharging via an external adapter.

[0022]

Thus, the above arrangement provides a delay at turn-on which allows the lamp filament to warm up. The lamp is at a very low current, or
In order to prevent unstable operation over a long period of time and shortening the life of the lamp, the filament current may be reapplied during operation well after turn-on, if the lamp operating conditions deteriorate. Although the above-described desirable circuit is more complex than currently used comparable lamp drive circuits, and thus somewhat costly, the use of such a circuit not only results in a longer lamp operating life, but also results in lower power consumption. It also brings great efficiency. The lamps are used at the optimum power factor where secondary breakdown occurs stably, and the lamp operating conditions are continuously and automatically monitored, and those conditions are automatically adjusted when necessary, taking into account unforeseen changes. No continuous extra power is required. In other words, the lamp does not need to be overpowered just to handle the worst predictable operating conditions. A coarser or simpler drive circuit will usually always supply more power than is actually needed, to avoid a shortage of power in all environments, at the expense of using up battery charge more quickly than necessary. Adjusted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a solar lamp driving circuit according to an embodiment of the present invention.

[Explanation of symbols]

 A Battery state detection circuit B Monitor circuit C Lamp drive circuit main part D Charge circuit

Continuation of the front page (56) References JP-A-59-73890 (JP, A) JP-A-60-189194 (JP, A) JP-A-1-213996 (JP, A) JP-A-61-256595 (JP) JP-A-62-145698 (JP, A) JP-A-63-143797 (JP, A) JP-A-54-27280 (JP, A) JP-A-1-122298 (JP, U) JP-A 58-20494 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) H05B 41/24

Claims (4)

(57) [Scope of request for utility model registration] A switch connected to control warm-up power supply to a filament of the lamp;
A lamp driving circuit connecting between a battery power supply including a solar cell and a battery, and a terminal of a fluorescent lamp including a boosting transformer arranged to supply high frequency power between an oscillator and the terminal, the lamp driving circuit comprising: A resistor pair for monitoring the operating state, and a switch connected to the junction of the resistor pair for increasing the oscillator output when the voltage at the junction representing the lamp operating state increases above a predetermined threshold. A sampling circuit comprising a first inverter for turning on the power supply, and a second circuit for suppressing the detection circuit connected to the detection circuit for detecting the state of the battery power supply so as to maximize the warm-up power supplied at the time of warm-up. A lamp driving circuit comprising: an inverter; 2. The system of claim 1 further comprising: a timer for controlling the switch; and a start delay circuit for delaying application of main operating power from the transformer to turn on the lamp at start so that the lamp filament can warm up. 2. The lamp drive circuit according to claim 1, wherein a timer is controlled by the start delay circuit to keep the switch closed for at least a few seconds after the lamp is turned on. 3. The system of claim 1, wherein each oscillator output is configured to decrease from a high starting level to a predetermined operating level after the lamp has been turned on for several seconds.
Or the circuit according to 2. 4. The system of claim 1 including a manually adjustable current regulator for changing the brightness of the lamp in use.
The circuit according to any one of claims 3 to 3.