JPS647477B2 - - Google Patents

Description

Detailed Description of the Invention The present invention connects a current-limiting element and a discharge lamp in series to a low-frequency AC power source (commercial power source), connects a high-frequency power source to the discharge lamp, brings the commercial power source voltage close to the lamp voltage, and discharges The present invention relates to a high-frequency superimposed high-pressure discharge lamp lighting device that stably lights a lamp.

Generally, low-frequency power is supplied to a high-pressure discharge lamp through a current-limiting element, and a high-frequency wave with a constant energy is superimposed during the restriking phase of each half cycle of the AC power supply for low-frequency power supply, and the power supply voltage and lamp There is a lighting device that lights a high-pressure discharge lamp every cycle by bringing the voltage close to each other, thereby reducing the loss of the ballast and making it smaller and lighter. In this lighting device, a high frequency is superimposed on a low frequency power source, so when the high frequency power is larger than the low frequency power, a phenomenon called acoustic resonance occurs, which causes the discharge arc column to become unstable, causing the light output to flicker.
Problems such as the lamp going out or the luminous tube cracking occur. Furthermore, if the high frequency power is too small, the restriking energy applied to the lamp will be insufficient, making it difficult to keep the lamp lit.

An object of the present invention is to provide a high-frequency superimposed high-pressure discharge lamp that regulates the ratio of high-frequency power W _H to low-frequency power W _L supplied to the discharge lamp, and maintains stable lighting of the discharge lamp so as not to cause an acoustic resonance phenomenon. The present invention provides a lighting device.

The present invention will be explained using one embodiment. FIG. 1 shows a configuration diagram of an embodiment, which includes an AC power source 1, a current limiting element 2, a discharge lamp 3, and a high frequency pulse generating circuit 4. Low frequency AC power is supplied to the discharge lamp 3 through the AC power source 1 and current limiting element 2, and high frequency power with constant energy is supplied by the pulse generating circuit 4 during the restriking phase of each half cycle of the AC power source. generated and compensates for the restriking voltage of the discharge lamp 3.

The operation will be explained below using a specific circuit example. FIG. 2 shows a circuit diagram of the pulse generating circuit 4, and FIG. 3 shows a timing chart. When the power supply 1 is turned on, the pulse generation circuit 4 shown in FIG. 1 operates,
A starting pulse is applied to the discharge lamp 3 and it lights up.
Thereafter, the power supply voltage waveform Vs (shown in Figure 3 A) is divided into positive and negative cycles, and in the positive cycle, the power supply consisting of a rectifier diode D ₁ a, a resistor R ₁ a, and a voltage regulator diode D ₂ a is divided into positive and negative cycles. The waveform is shaped by the waveform shaping circuit 5a, resulting in a power supply waveform as shown in FIG. 3(b). Waveform B is sent to the oscillation circuit 7a and the oscillation control circuit 6a. In the oscillation control circuit 6a, waveform B is connected to a resistor.
The waveform is integrated using R ₆ a, capacitor C ₂ a (waveform C), and applied to the base of transistor Q ₃ a, and is applied to the base of transistor Q ₃ a and Q ₄ a and resistors R ₇ a, R ₈ a, R ₉ a. is sent to a voltage comparison detector consisting of a resistor R ₁₀ a,
The waveform is shaped by the potential determined by R ₁₁ a (which becomes the base potential of the transistor Q ₄ a). The output of the voltage comparison detector, ie, the collector potential of the transistor Q ₄ a, has its DC component removed by a capacitor C ₃ a, and is applied to the transistor Q ₁ a in the oscillation circuit 7a through a diode D ₃ a. On the other hand, the oscillation circuit 7
Similar to the oscillation control circuit 6a, a waveform is applied to a. In the oscillation circuit 7a, the transistor Q ₁ a
When OFF, the oscillation operation is repeated continuously at the frequency specified by the resistor R ₂ a and capacitor C ₁ a. [By optimally selecting resistors R ₃ a and R ₄ a, PUT (Programmable Unijunction Transistor)
Q ₂ a operates in continuous oscillation. ]Here the capacitor
Transistor Q ₁ a is connected between the collector and emitter of C ₁ a.
When short-circuited, the anode potential of PUTQ ₂ a becomes zero, and the oscillation of PUTQ ₂ a stops. That is, the oscillation operation stops only in the portion where the signal exists in waveform D in FIG. 3. (Waveform E) The oscillation waveform of PUTQ ₂ a operates the switching transistor Q ₅ through the pulse transformer T ₁ a. Next, the negative cycle will be explained. In the negative cycle, the power supply waveform shaping circuit 5
The internal configuration is the same except that the positive cycle system consisting of the oscillation circuit 7a, oscillation control circuit 6a, and the power supply 1 are wired in reverse. That is, the power waveform shaping circuit 5b is connected to 5a, and the oscillation circuit 7b is connected to 7a.
Since it has the same circuit configuration as , the explanation of its operation will be omitted. In the negative cycle, the signal is converted into a waveform and a waveform G is obtained from the oscillation circuit 7b. Waveform T is applied to switching transistor _Q6 . the result,
Transistor _Q5 operates for positive cycles,
Transistor _Q6 operates for negative cycles. Transistors Q ₅ and Q ₆ are connected to a DC power supply from a power supply 1 through a transformer T ₂ which is full-wave rectified by a diode bridge _{DB 1} and smoothed by a capacitor C ₄ . A pulse of both positive and negative polarity (re-ignition pulse) shown in Figure H is output and applied to the discharge lamp 3 via the capacitor _C5 to maintain lighting. Note that the capacitor _C5 has the role of cutting off low frequency components from the discharge lamp 3 side. In Fig. 3, the application range of the restriking pulse is determined by the integral constant of the oscillation control circuit 6a (determined by the resistor _R6a and capacitor Cza) or the reference voltage (resistance _R10a and
(determined by the division ratio with R ₁₁ a).

Next, the relationship between the power ratio of the high-frequency power W _H supplied to the discharge lamp 3 from the pulse generation circuit 4 and the low-frequency power W _L supplied from the main power supply circuit, acoustic resonance phenomenon, and extinction is determined at 150W high color rendering. This will be explained using an example of experimental results using a high-pressure sodium lamp.

Figure 4 shows whether or not acoustic resonance occurs and whether fading occurs by changing W _L and W _H in a 150 W high color rendering high pressure sodium lamp. The following can be seen from this figure.

If the power ratio between the high frequency power W _H supplied to the discharge lamp and the low frequency power supplied from the main power supply circuit is set to 1/6 or less, no acoustic resonance phenomenon will occur.

If the power ratio between the high frequency power W _H supplied to the discharge lamp and the low frequency power W _L supplied from the main power supply circuit is 1/20 or more, the lamp can be kept stably lit without turning off.

From the above results, the power ratio of the high frequency power W _H supplied to the discharge lamp and the low frequency power W _L supplied from the main power supply circuit is 1/20W _H /W _L 1/6
It can be seen that a 150W high color rendering high pressure sodium lamp can be stably lit without causing any acoustic resonance phenomenon.

Further, the present invention is applicable not only to pulsed high frequency power but also to high frequency power of various waveforms such as a sine wave.

The present invention brings about the following effects.

Keeps the power supply voltage and lamp voltage close to each other for stability without causing acoustic resonance and fading.
Can light up a 150W high color rendering high pressure sodium lamp.

Since the impedance voltage of the current limiting element can be reduced, the current limiting element can be made smaller.

Ballast power loss is reduced.

This is because the copper loss and iron loss of the choke coils are reduced as the ballast becomes smaller.

When the power supply voltage and lamp voltage are brought close to each other and the lamp is turned on,
Since the lamp voltage and lamp power characteristics of the 150W high color rendering high pressure sodium lamp are in the negative characteristic region, the lamp can be operated stably despite fluctuations in lamp characteristics and supply voltage, and the lamp voltage increases at the end of its life. It is possible to easily prevent fading due to

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a circuit diagram of a pulse generating circuit used in the present invention, and FIG. 3 is a timing chart. FIG. 4 shows the relationship between low frequency power W _L , high frequency power W _H , fading, and acoustic resonance in a 150 W high color rendering high pressure sodium lamp. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Current limiting element, 3... Discharge lamp, 4... Pulse generation circuit, 5a, 5b...
Power supply waveform shaping circuit, 6a, 6b...Oscillation control circuit, 7a, 7b...Oscillation circuit.

Claims (1)

[Claims] 1. A main power supply circuit consisting of a current limiting element and a 150W high color rendering high pressure sodium lamp connected in series to a low frequency AC power supply, and a high frequency power supply circuit connected in parallel to the high color rendering high pressure sodium lamp. and high frequency power relative to the low frequency power W _L supplied to the high color rendering high pressure sodium lamp.
A high-pressure discharge lamp lighting device characterized in that the high-color-rendering high-pressure sodium lamp is lit with a ratio of W _H in the range of 1/20≦W _H /W _L ≦1/6.