JPS6412077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device, and in particular is improved so that efficiency can be improved by superimposing a direct current or a low-frequency alternating current and a high-frequency current in series and supplying the same to the discharge lamp. The present invention relates to a discharge lamp lighting device.

Generally, in a discharge lamp lighting device, a glow starter or an electronic starter is used to start and light the discharge lamp, and after the discharge lamp is started and lit, the operation of the glow starter or electronic starter is stopped and the power supply voltage is used to restart the discharge lamp. A so-called conventional lighting device is used that keeps the light on.

By the way, those skilled in the art know that efficiency can be improved by lighting a low-pressure steam discharge lamp, which is an example of a discharge lamp, at a high frequency.

FIG. 1 is a characteristic diagram showing the relationship between the frequency of the driving power source and the efficiency in a low-pressure gas discharge lamp. In the figure, if the efficiency when lighting a discharge lamp with a DC power supply is 100%, then when a high frequency oscillation circuit with an oscillation frequency of approximately 20KHz is energized with a DC power supply, the efficiency is approximately 20% as shown by the solid line. Can improve efficiency.
Furthermore, when the same high-frequency oscillation circuit is energized by a low-frequency AC power source, the efficiency can be improved by several percent as shown by the dotted line even when no smoothing circuit is used.

Therefore, conventionally, a transistor inverter circuit has been proposed as a lighting device for lighting a discharge lamp at high frequency. However, conventional transistor inverter circuits require a large number of semiconductor elements and other electronic components, resulting in an increased number of components and high costs. In addition, because of the large number of parts, assembly work was complicated, making it unsuitable for mass production and resulting in poor production efficiency. In addition, when a lighting device using a transistor inverter uses a commercial AC power source, there is a problem that if a smoothing circuit is omitted in order to obtain a high power factor, a rest period will occur and the luminous efficiency will decrease. If an attempt was made to increase the luminous efficiency by providing a smoothing circuit, there was also the drawback that it would become even more expensive.

Therefore, the main object of the present invention is to provide an improved discharge lamp lighting method that not only improves luminous efficiency through high-frequency lighting, but also has a simple circuit configuration, a small number of parts, and can be manufactured at low cost. It is.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a basic block diagram of the invention. In the configuration, a main power supply 1 of direct current or low frequency alternating current includes a high frequency block circuit 2 and a discharge lamp 3.
and a high frequency power source 4 are connected in series. The main power supply 1 and the high frequency block circuit 2 are, for example, a third
As shown in Figure a, an inductor 2a is connected to a low frequency AC power supply (commercial AC power supply) 1a, a third
As shown in Figure b, an inductor 2 is connected to the low frequency power supply 1a.
a and a phase advancing capacitor 2b, a constant current power supply with an inductor 2a connected in series to a constant current source 1c as shown in Figure 3c, or a DC power supply 1d with an inductor 2a as shown in Figure 3d. Those connected in series are used.

The high frequency power source 4 has low impedance characteristics with respect to the direct current or low frequency alternating current supplied from the main power source 1.

A high frequency current supply path 5 is connected in parallel to the series circuit of the main power source 1 and the low frequency block circuit 2 or the series circuit of the high frequency power source 4 and the discharge lamp 3. This supply path 5 has the function of passing at least the high frequency current from the high frequency power source 4 and blocking low frequency waves, and depending on the configuration of the high frequency power source 4, it may also pass the high frequency current in the form of a pulse or sawtooth waveform into a smooth waveform. Any suitable circuit can be used as long as it has the function of waveform shaping. For example, as the high frequency current supply path 5, a tank circuit in which a high frequency pass circuit 51 and a waveform shaping circuit 52 are connected in series is used as shown in the illustrated example.

Next, the basic operation of this invention will be explained with reference to FIG. First, the discharge lamp 3 is started and lit by some means. Then, a direct current or low frequency current from the main power source 1 is supplied to the discharge lamp 3 via the high frequency block circuit 2 and the high frequency power source 4. At the same time, the high frequency power supply 4 generates a high frequency voltage. At this time, the high frequency voltage is prevented from leaking to the main power supply 1 side by the high frequency block circuit 2, and passes through the high frequency current supply path 5, so that
A high frequency current flows through the closed circuit of the high frequency power source 4 - discharge lamp 3 - high frequency current supply path 5 - 4. That is, the high frequency current bypasses the main power supply 1 and the high frequency block circuit 2, is superimposed on the input current (direct current or low frequency alternating current), and is supplied to the discharge lamp 3. At this time, if the high frequency current generated by the high frequency power supply 4 has an intermittent pulse waveform, for example, the waveform shaping circuit 52 shapes the waveform into a smooth continuous waveform (for example, a sine wave waveform). . Therefore, the direct current or low frequency current from the main power source 1 and the waveform-shaped high frequency current flow through the discharge lamp 3 in a superimposed manner. This significantly improves the efficiency of the discharge lamp 3.

More specific examples will be described below.

FIG. 4 is a specific circuit diagram of an embodiment of the present invention. In the configuration, a low-frequency AC power supply (hereinafter referred to as AC power supply) 1a, which is an example of a main power supply, includes an inductor 2a, which is an example of a high-frequency block circuit, a high-frequency oscillation circuit 4, which is an example of a high-frequency power supply, and a low-pressure vapor discharge lamp (hereinafter abbreviated as discharge lamp). ) 3 are connected in series. This high frequency oscillation circuit 4 includes an oscillation capacitor 4
1. A two-directional two-terminal thyristor (hereinafter abbreviated as thyristor), which is an example of a current-controlled nonlinear resistance element.
42 and a boost inductor 43 are connected in parallel. A tank circuit 5, which is an example of a high frequency current supply path, is connected in parallel to the series circuit of the AC power source 1a and the inductor 2a. The tank circuit 5 includes a capacitor 51 that passes high frequency current and blocks low frequency current, and an inductor 5 for waveform shaping.
2 are connected in series. Note that when using the illustrated example of the high-frequency oscillation circuit 4, the waveform shaping inductor 52 is essential because the high-frequency current is pulsed.

FIG. 5 is a waveform diagram for explaining the operation of FIG. 4, in particular, a shows an example of the output waveform of the high frequency oscillation circuit 4, and b shows a waveform obtained by enlarging the time axis of a.

Next, the operation of the discharge lamp 3 during lighting will be described with reference to FIGS. 4 and 5. discharge lamp 3
During lighting, a low frequency current flows through the path of AC power supply 1a - inductor 2a - high frequency oscillation circuit 4 - discharge lamp 3. At this time, the oscillation capacitor 4 of the high frequency oscillation circuit 4 is
1 is charged. When the terminal voltage of the oscillation capacitor 41 exceeds the breakover voltage of the thyristor 42, the thyristor 42 becomes conductive. In response, the oscillation capacitor 41 and the boost inductor 43 cooperate to start high frequency oscillation operation. This oscillation output and thus the high frequency current increases with increasing input current. The high frequency current generated in this way is blocked by the inductor 2a and capacitor 51.
Therefore, it flows into the closed circuit of the high frequency oscillation circuit 4, the discharge lamp 3, and the tank circuit 5. At this time, the oscillation current generated by the high frequency oscillation circuit 4 is a pulsed current with a large sharpness as shown by the two-dot chain line in FIG. However, since the waveform is shaped by the inductor 52, the high-frequency current iH flowing in the closed circuit becomes a sine wave as shown by the solid line in Fig. To increase. Furthermore, since the high frequency oscillation circuit 4 has a low impedance characteristic during its oscillation operation, a relatively large low frequency current iL (FIG. 5c) is supplied to the discharge lamp 3 from the AC power supply 1a.
Therefore, a tube current iT (see FIG. 5a) in which a sinusoidal high-frequency current iH and a low-frequency current iL are superimposed in series flows through the discharge lamp 3.

As described above, according to this embodiment, since the discharge lamp is maintained lit by the tube current which is a combination of a low frequency current and a high frequency current, there is an advantage that the discharge lamp can be lit at high frequency and the efficiency can be improved. Further, since the high frequency current is shaped into a substantially sinusoidal waveform by the tank circuit 5, there is an advantage that efficiency can be further improved. By the way, according to this example, the lighting time is approximately 15% compared to the conventional method that uses commercial AC power.
Can improve efficiency. Furthermore, since the input current is reduced for the same optical output, the loss of the inductor 2a is reduced, and the efficiency is actually further improved, and at the same time, the inductor 2a can be made smaller.

By the way, in the embodiment shown in FIG.
Although only the case after lighting has been described and the starting circuit has not been mentioned, appropriate starting means are required depending on the type of discharge lamp. Therefore, a specific circuit including the starting circuit will be explained below.

FIG. 6 is a specific circuit diagram of another embodiment of the present invention. This embodiment differs from FIG. 4 in that a hot cathode low pressure steam discharge lamp is used as an example of the discharge lamp 3, and the filament 3 of the discharge lamp
A series circuit of a second high frequency blocking inductor 61 and a glow starter 62 as an example of the starting means 6 is connected to the non-power supply side ends of the motors 1 and 32.
Since the other configurations are the same as those in FIG. 4, the same parts are indicated by the same reference numerals and detailed explanation thereof will be omitted.

In operation, when the AC power supply 1a is turned on,
The glow starter 62 starts glow discharge, and the bimetallic contacts are closed and become conductive. Accordingly, from the AC power supply 1a to the inductor 2a - oscillation capacitor 41 - filament 31 - inductor 61 - glow starter 62 - filament 32
-1a, current flows through the oscillation capacitor 4
1 is charged. Then, when the terminal voltage of the oscillation capacitor 41 exceeds the breakover voltage of the thyristor 42, the thyristor 42 becomes conductive. As a result, the oscillation capacitor 41 and the boost inductor 4
The high frequency oscillation circuit 4 starts a step-up oscillation operation due to the cooperative action of the two, and generates a high frequency high voltage. While the high frequency oscillation circuit 4 is in oscillation operation, its low frequency impedance is small, so the filaments 31 and 32 of the discharge lamp 3 are preheated by the large input current of the high frequency oscillation circuit 4. At this time, since the high frequency high voltage of the high frequency oscillation circuit 4 is blocked by the inductors 2a and 61, the high frequency high voltage is applied to both ends of the discharge lamp 3.

In this way, when the glow switch 62 is opened after the filaments 31 and 32 have been sufficiently preheated, the high frequency high voltage and the kick voltage generated across the inductor 2a are superimposed and applied to both ends of the discharge lamp 3, and the discharge lamp 3 starts and lights up. Once the discharge lamp 3 is started and lit, the glow starter 62 remains non-conductive due to the high frequency blocking action of the inductor 61. As a result, the high frequency current generated by the high frequency oscillation circuit 4 flows into the closed circuit of the high frequency oscillation circuit 4 - discharge lamp 3 - tank circuit 5. At the same time, input current from the AC power source 1a is supplied to the discharge lamp 3 via the high frequency oscillation circuit 4. Therefore, a tube current in which a low frequency current and a high frequency current are superimposed flows through the discharge lamp 3. In this way, the discharge lamp 3 is lit at high frequency.

FIG. 7 is a specific circuit diagram of still another embodiment of the present invention. This embodiment differs from FIG. 6 in that a preheating circuit 6a consisting of a series circuit of an inductor 61 and a capacitor 63 is used instead of the starting means 6.
This is because we used

Next, the operations of this embodiment that differ from those in FIG. 6 will be explained. When starting the discharge lamp 3,
The inductor 2a and the capacitor 63 resonate in series,
A low frequency current flows to the preheating circuit 6a, the high frequency oscillation circuit 4 operates in oscillation, and the filament 3
1,32 are preheated. And filament 3
1 and 32 are sufficiently preheated, the high frequency oscillation circuit 4
The discharge lamp 3 is started and lit by the oscillation voltage. When the discharge lamp 3 is started and lit, a high frequency current is supplied from the high frequency oscillation circuit 4 to the discharge lamp 3 via the tank circuit 5. At this time, AC power supply 1
The low frequency current supplied from a is divided and flows into the preheating circuit 6a and the discharge lamp 3. As a result, the high-frequency current and the low-frequency current are superimposed in the discharge lamp 3, and the mixing ratio of the high-frequency current is the sixth.
Since the tube current is supplied as a tube current higher than that shown in the figure, the efficiency is improved compared to that shown in FIG. 6. Incidentally, even if the phase advance capacitor 2b is connected in series with the inductor 2a and the capacitor 63 of the preheating circuit 6a is omitted, the phase advance capacitor 2b and the inductor 6
1 can be caused to resonate in series.

By the way, various other modifications of the starting means are conceivable. For example, a preheating circuit 6b consisting of a series circuit of a high frequency blocking inductor 61 and a thyristor 64 may be used. In this case, when the discharge lamp 3 is started, the thyristor 64 becomes conductive at a voltage equal to or higher than a certain voltage of the power supply voltage. As the thyristor 64 becomes conductive, the high frequency oscillation circuit 4 starts oscillating, applying a high frequency high voltage to the discharge lamp 3 and preheating the filaments 31 and 32 with the low frequency current flowing through the preheating circuit 6b. On the other hand, once the discharge lamp 3 is started and lit, the tube voltage of the discharge lamp 3 decreases and does not reach the breakover voltage of the thyristor 64. Therefore, the preheating circuit 6b is disabled after the discharge lamp 3 is started and lit. Note that the inductor 61 prevents the thyristor 64 from being erroneously conductive due to the high frequency high voltage or impulse of the high frequency oscillation circuit 4 while the discharge lamp 3 is lit.

Further, as another example of the starting means, the preheating circuit 6c
The circuit may be configured as follows. That is, the preheating circuit 6c of this embodiment includes a high frequency blocking inductor 61, a diode 65, and a capacitor 6.
The parallel circuit b and the thyristor 64 are connected in series. Preheating circuit 6 of this embodiment
c is one polarity of the power supply voltage, that is, diode 6
4, the capacitor 66 is charged to the illustrated polarity, so when the voltage of the AC power source 1a becomes reverse polarity in the next half cycle, the charging voltage of the capacitor 66 is superimposed on the power supply voltage, and the thyristor 64 As a result, the thyristor 64 is turned on at an earlier phase than the preheating circuit 6b. This has the advantage of increasing the preheating current.

Incidentally, in the embodiments shown in FIGS. 6 and 7, the filament is preheated using the starting means 6 or 6a to 6c, and the high frequency oscillation circuit 4 is also used as a part of the starting means. Alternatively, the discharge lamp may be started and lit using a starting means that generates a high voltage by itself.

FIG. 8 is a specific circuit diagram of such an embodiment. This embodiment differs from FIG. 6 in that a high frequency high voltage generating circuit 7 (hereinafter referred to as a booster circuit) is connected to the non-power supply side of the discharge lamp 3. This boost circuit 7 includes a thyristor 72 and a boost inductor 7.
The bias winding 74 that applies a deep positive bias to the boost inductor 73 and the series circuit of the oscillation capacitor 71 are connected in parallel to the series circuit of No. 3.

In operation, when the AC power supply 1a is turned on,
Inductor 2a - Oscillation capacitor 41 - Filament 31 - Bias winding 74 - Oscillation capacitor 7
A low frequency current flows through the path of 1-filament 32-1a, and oscillation capacitors 41 and 71 are charged. When the terminal voltage of the oscillation capacitor 41 exceeds the breakover voltage of the thyristor 42, the high frequency oscillation circuit 4 operates in oscillation in the same manner as described above. Further, when the terminal voltage of the oscillation capacitor 71 exceeds the breakover voltage of the thyristor 72, the thyristor 72 becomes conductive. This causes the booster circuit 7 to operate in oscillation. The high frequency high voltage generated by the booster circuit 7 is applied to the discharge lamp 3, and at the same time, the filaments 31 and 32 are preheated by the input current of the booster circuit 7. When the filaments 31 and 32 are thus sufficiently preheated, the discharge lamp 3 is started and lit based on the high frequency and high voltage. When the discharge lamp 3 starts and lights up, the tube voltage no longer reaches the breakover voltage of the thyristor 72, the boost circuit 7 stops oscillating operation, and the discharge lamp 3 receives low frequency current from the AC power supply 1a and from the high frequency oscillation circuit 4. The light is maintained by high frequency current. The bias winding 74 serves to downsize the boost inductor 73 required to generate a predetermined high frequency and high voltage, and
The high frequency voltage of the high frequency oscillation circuit 4 is prevented from passing through the oscillation capacitor 71 while the discharge lamp 3 is lit.

In FIG. 8, an intermittent oscillation capacitor 9 is connected in series to the booster circuit 7 to form an intermittent high-frequency high-voltage generating circuit (hereinafter referred to as a high-voltage circuit) 8, and the discharge lamp 3 is connected every half cycle of the AC power supply 1a. It may be a so-called every-cycle start lighting device that maintains lighting while re-igniting.

In the case of such an every-cycle start lighting device, when the high frequency oscillation circuit 4 and the booster circuit 7 start the oscillation operation as described above, the intermittent oscillation capacitor 9 is gradually charged with this oscillation operation, and the intermittent oscillation The terminal voltage of the oscillation capacitor 9 cancels out the power supply voltage, so that the thyristor 7
2 is turned off, and the booster circuit 7 stops its oscillation operation. Therefore, an intermittent oscillation output is generated from the high voltage circuit 8 at each predetermined phase of each half cycle of the AC power supply voltage. This oscillation output is superimposed on the power supply voltage and applied to the discharge lamp 3. At the same time, during the oscillation period of the high voltage circuit 8, the input current flows through the filaments 31 and 32, causing the filament 3 to
Preheat 1 and 32. Thus, when the filaments 31 and 32 are sufficiently preheated, the discharge lamp 3 is triggered by the oscillation output from the high voltage circuit 8.
is started. When the discharge lamp 3 starts and lights up,
Since the sum of the voltage across the discharge lamp 3 and the terminal voltage of the intermittent oscillation capacitor 9 falls below the breakover voltage of the thyristor 72, the high voltage circuit 8 stops its oscillation operation.

In the next half cycle, the terminal voltage of the intermittent oscillation capacitor 9 is superimposed on the power supply voltage, so the high voltage circuit 8 again operates to oscillate and re-ignites the discharge lamp 3, and after the discharge lamp 3 is re-ignited. stops the oscillation operation for the same reason as above.

In the same manner, the discharge lamp 3 is connected to the AC power source 1a.
While being re-ignited by the intermittent oscillation output of the high-voltage circuit 8 every half cycle, the high-frequency lighting is carried out by a current that is a combination of a high-frequency current and a low-frequency current.

In this way, the high-voltage circuit 8 is connected in parallel to the discharge lamp 3, the discharge lamp is re-ignited every half cycle of the power supply voltage, and the discharge lamp 3 is supplied with a superimposed current of high-frequency current and low-frequency current. By supplying the voltage, the power supply voltage can be lowered compared to conventional lighting devices that re-ignite the discharge lamp using only the power supply voltage, and the difference voltage between the power supply voltage and the tube voltage of the discharge lamp can be reduced. As a result, the inductor 2a that shares this differential voltage can be further downsized and losses can be reduced.

Furthermore, if a cycle-by-cycle lighting device is used, the discharge lamp can be used with positive characteristics, so the efficiency can be improved by about 20%. Therefore, as in this embodiment, a current in which a low-frequency current and a high-frequency current are superimposed is supplied to the discharge lamp as a tube current, and the cycle-start lighting device is used to restart the lamp every half cycle of the power supply voltage. By doing so, the efficiency can be improved by about 35% compared to conventional lighting devices, which has the advantage of achieving a significant improvement in efficiency. Furthermore, if the luminous efficiency is selected to be the same as that of a conventional lighting device, the input current can be reduced accordingly, which has the advantage of allowing the inductor 2a to be significantly downsized.

In the embodiment shown in FIG. 8, the same effect can be obtained even if the series circuit of the oscillation capacitor 71 and the bias winding 74 of the high voltage circuit 8 is directly connected to the non-power supply side ends of the filaments 31 and 32. Further, in the booster circuit 7 or the high voltage circuit 8, a series circuit of the oscillation capacitor 71 and the bias winding 74 may be connected to the power supply side ends of the filaments 31 and 32. In that case, the oscillation current of the booster circuit 7 or high voltage circuit 8, which is larger than the input current, causes the filaments 31, 32 to
You can preheat it with

As described above, according to the present invention, a discharge lamp can be efficiently lit with a simple configuration and at low cost, and furthermore, the lighting device can be miniaturized, and other unique effects are achieved.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between the frequency and efficiency of the power supply supplied to the discharge lamp. FIG. 2 is a basic block diagram of one embodiment of the present invention.
FIG. 3 is a circuit diagram of various modifications of the main power supply 1 and the high frequency block circuit. FIG. 4 is a specific circuit diagram of an embodiment of the present invention. Figure 5 is the 4th
FIG. 3 is a waveform diagram for explaining the operation shown in the figure. 6th
7 and 8 are specific circuit diagrams of other embodiments of the present invention. In the figure, 1 is the main power supply, 1a is a low frequency AC power supply, 2 is a high frequency block circuit, 2a is an inductor for high frequency blocking, 3 is a discharge lamp, 4 is a high frequency power supply (high frequency oscillation circuit), and 5 is a high frequency current supply path ( tank circuit), 51 is a high frequency pass circuit (capacitor), 52 is a waveform shaping circuit (waveform shaping inductor), 6 to 8 are starting means {7 is a high frequency high voltage generation circuit (boost circuit), 8 is an intermittent high frequency high voltage Generation circuit (high voltage circuit)}, 41, 71 are oscillation capacitors, 42, 64, 72 are current controlled nonlinear resistance elements (thyristors), 43, 73 are boost inductors,
61 is a high frequency block inductor, 62 is a glow switch, 63 and 66 are capacitors, 65 is a diode, 74 is a bias winding, and 9 is an intermittent oscillation capacitor.

Claims (1)

[Claims] 1. A DC or low-frequency main power supply, a high-frequency block circuit connected in series to the main power supply and including at least an inductor, and energized by the main power supply and including a thyristor, an inductor, and a capacitor. A high frequency power supply having a low frequency blocking function is connected in series with a discharge lamp, and includes at least a high frequency pass capacitor between the rear end side of the high frequency block circuit and the rear end side of the discharge lamp. A discharge lamp lighting device in which a power supply path is connected and a direct current or low frequency current from the main power source and a high frequency current output from the high frequency power source are superimposed and supplied to the discharge lamp.