JPH0550839B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a discharge lamp lighting device having constant power characteristics using a phase control type ballast.

[Prior art]

Conventionally, as a constant power discharge lamp lighting device using a phase control type ballast, one having a configuration as shown in FIG. 1 is known. That is, in the figure, 1 is an AC power supply, and the power supply 1 includes a bidirectional switching element (hereinafter referred to as a triax) 2 for controlling the lamp current, a main chain coil 3,
High-pressure discharge lamps such as mercury lamps and sodium lamps 4
A series circuit with the triac 2 is connected.
A bypass reactor 5 is connected in parallel. Reference numeral 6 denotes a power supply voltage detection circuit, which is connected to both terminals 1a and 1b of the AC power supply 1. Reference numeral 7 denotes a lamp current zero cross detection circuit which detects the zero crossing point of the lamp current and sends out a synchronizing signal to start setting the conduction phase angle of the triac 2 every half cycle; 1a, and is connected to the connection point between the main chiyoke coil 3 and the high pressure discharge lamp 4. Reference numeral 8 denotes a voltage detection circuit, which detects the voltage between the series circuit of the triax 2 and the main choke coil 3, and similarly to the lamp current zero cross detection circuit 7, it detects the voltage between one terminal 1a of the power supply 1 and the main choke coil 3. and a connection point between the high pressure discharge lamp 4 and the high pressure discharge lamp 4. Reference numeral 9 denotes a comparison pulse generation circuit which receives the power supply voltage detection signal from the power supply voltage detection circuit 6 and the voltage detection signal from the voltage detection circuit 8, and adjusts the voltage detected by the voltage detection circuit 8 when starting the discharge lamp. The conduction phase angle of the triax 2 is set in response to the power supply voltage, and after the lamp voltage reaches a predetermined value after starting the discharge lamp, the conduction phase angle of the triax 2 is set in response to the power supply voltage. It sends driving pulses toward the gate terminal of triac 2, and one terminal 1a of power supply 1
and is connected to the gate of triax 2. The synchronizing signal from the lamp current zero cross detection circuit 7 is input to the comparison pulse generation circuit 9, which generates a gate pulse for triac drive with a controlled phase angle every half cycle. .

In a discharge lamp lighting device configured in this way, when the power is turned on and the discharge lamp starts, the lighting operation of the discharge lamp reaches a stable state from a state where the lamp voltage is zero until the lamp voltage reaches a predetermined value. teeth,
In the comparison pulse generation circuit 9, the triack 2
The conduction phase angle of the triac 2 is set in response to the voltage between the main choke coil 3 and the triac 2, and upon receiving a synchronizing signal from the lamp current zero cross detection circuit 7, a triac driving pulse is output to the gate every half cycle. Triax 2 is made conductive at a set phase angle.

When the vapor pressure of the metal enclosed in the high-pressure discharge lamp 4 rises to a normal lighting state, and the lamp voltage exceeds a certain value, that is, the voltage between the triac 2 and the main choke coil 3 detected by the voltage detection circuit 8 is When the voltage falls below a certain value, the conduction phase angle of the triac 2 is set in response to the power supply voltage, and a gate pulse is sent out every half cycle. As a result, constant power is supplied to the discharge lamp 4, and the light emission output of the lamp is maintained at a predetermined level.

However, in such a discharge lamp lighting device, when operating a high-pressure discharge lamp that requires a high operating voltage, such as a large-capacity metal halide lamp or xenon lamp, a step-up transformer is required as shown in Figure 2. 10 is used to apply a high voltage on the secondary side to the lighting device.

In this way, using a step-up transformer, for example, 1500V
When applying such a high secondary voltage, the impedance of the bypass reactor 5 is set to be much higher than the impedance of the main choke coil 3 at the moment when the triax 2 becomes non-conductive, so the impedance of the bypass reactor 5 is set to be approximately 1500×√ Since a voltage of 2V is applied between both terminals of the triax 2, it is necessary to select a triax with a withstand voltage of about 3000V. Generally, a triac with a withstand voltage of 3000V has a rated current of about 100 to 500A, making the triac itself very expensive. However, the lamp current in a general high-pressure discharge lamp is at most
Since it is about 10A, the withstand voltage is 3000V and the rated current is 100V.
If a triac of ~500A is used, it will be used for current control of less than 1/10 of the rated current, which is extremely uneconomical.

In addition, the voltage detection circuit 8 and lamp current zero cross detection circuit 7, which constitute the triax conduction phase angle control device, are also connected to a normal commercial power source, for example, 200V.
A problem arises in that the one for the 200V power supply cannot be used, and a newly designed one for high voltage needs to be used, which is not compatible with the one for the 200V power supply.

[Purpose of the invention]

The present invention was made in order to solve the problems when using the constant power discharge lamp lighting device as a lighting device for a high pressure discharge lamp that requires high voltage. It is an object of the present invention to provide a constant voltage discharge lamp lighting device for a high voltage lighting circuit, in which the lamp current zero cross detection circuit, voltage detection circuit, etc. that constitute a triax conduction phase angle control device can be used as they are. .

[Summary of the invention]

The present invention provides a power source in the primary winding of an isolated step-up transformer, a high-pressure discharge lamp in the secondary winding, and a high-pressure discharge lamp connected in series with the first winding of a Chi-Yoke coil type ballast configured by magnetically coupling three windings. A triax is connected to the second winding of the ballast, and the conduction phase angle of the triax is determined based on the power supply voltage input to the comparison pulse generation circuit and the voltage of the third winding of the ballast. The lamp is configured to supply constant power to the high pressure discharge lamp, and electrically insulates and separates the triax and a comparison pulse generation circuit for controlling the conduction phase angle of the triax from the high pressure discharge lamp circuit. , it is possible to use a triax for low voltage and a comparison pulse generation circuit for controlling the conduction phase angle for low voltage.

〔Example〕

Examples will be described below. FIG. 3 is a block diagram of an embodiment of a constant power discharge lamp lighting device for a high voltage circuit according to the present invention. In the figure, 1
1 is a commercial AC power supply (for example, 200V), and the power supply 1
A primary winding 13 of an insulated step-up transformer 12 is connected between both terminals 11a and 11b of the transformer 1.
Terminals 14a, 1 of the secondary winding 14 of the transformer 12
4b, a first winding 16 of a chiyoke coil type ballast 15 having three magnetically coupled windings.
A series circuit of a high-pressure discharge lamp 19, which is a load and requires a high operating voltage, is connected to the high-pressure discharge lamp 19. Stabilizer 1
A triac 20 is connected to both ends of the second winding 17 of the power supply 5, and one end of the second winding is connected to one terminal 11a of the power source.

At both ends of the third winding 18 of the ballast 15, a lamp current zero cross detection circuit 21 and a ballast voltage detection circuit 22 having the same configuration as the conventional one shown in FIG.
is connected, and one end of the third winding 18 is similarly connected to one terminal 11a of the power source 11. Reference numeral 23 denotes a power supply voltage detection circuit, which is connected between both terminals 11a and 11b of the power supply 11. Reference numeral 24 denotes a comparison pulse generation circuit, which has the same configuration as the conventional one shown in FIG.
2 and a power supply voltage detection circuit 23, the conduction phase angle of the triac 20 is set, and a driving pulse is supplied to the gate of the triac 20. Note that, similar to the conventional one shown in FIG. 1, the synchronization signal from the lamp current zero cross detection circuit 21 is input to the comparison pulse generation circuit 24, and the phase angle is controlled for every half cycle. It is configured to generate a gate pulse for.

As shown in FIG. 4A and FIG. 4B, which is a cross-sectional view taken along the line A gap 32 is formed in the gap 32 . The first winding 16 is connected to the gap 3 of the central leg 31a.
The second winding 17 is arranged from the center to the bottom of the center leg 31a so as to surround the second winding 17 and the first winding 17.
The central leg 31a is spaced apart from and above the winding.
are arranged around. Further, the third winding 18 is arranged around the outer periphery of the first winding 16.

The operation of the constant power discharge lamp lighting device configured as described above is as follows. That is, the lamp current zero cross detection circuit 21 detects the zero cross point of the lamp current from the voltage generated in the third winding 18 of the choke coil type ballast 15. The ballast voltage detection circuit 22 converts the voltage generated in the first winding 16 of the ballast 15 due to the flow of the lamp current into a value determined by a predetermined turns ratio, and converts the voltage generated in the third winding 18 to a value determined by a predetermined turns ratio. To detect.

On the other hand, the power supply voltage detection circuit 22 detects the power supply voltage and inputs the detection signal thereof and the detection signal from the ballast voltage detection circuit 22 to the comparison pulse generation circuit 24, respectively. Comparison pulse generation circuit 2
4, similarly to the conventional one shown in FIG.
The conduction phase angle of the triac 20 is set in response to the voltage generated in the triac 20, and upon receiving a synchronizing signal from the lamp current zero cross detection circuit 21, a drive pulse is output to the gate every half cycle.
0 conducts at a set phase angle.

When the lamp voltage exceeds a certain value, that is, when the voltage detected by the ballast voltage detection circuit 22 becomes below a certain value, the conduction phase angle of the triax 20 is set in response to the power supply voltage. ,
A gate pulse is sent every half cycle to make triac 20 conductive.

When the triax 20 connected between the second winding 17 of the ballast 15 becomes conductive, the impedance of the first winding 16 of the ballast 15 decreases. Therefore, by controlling the conduction phase angle of the triax 20 in response to the lamp voltage or power supply voltage,
The current flowing through the first winding is controlled so that constant power is supplied to the high pressure discharge lamp regardless of fluctuations in lamp voltage and power supply voltage.

As is clear from the block diagram of this embodiment, the second winding 17 and the third winding 1 of the ballast 15
8 and the closed circuit of the triax 20 connected to these windings, the lamp current zero cross detection circuit 21, the ballast voltage detection circuit 22, the comparison pulse generation circuit 24 and the power supply voltage detection circuit 23, all of which are boosted. It is completely electrically isolated from the lamp circuit connected to the secondary winding 14 of the transformer 12.

Then, at the time of starting the discharge lamp, that is, when the load is short-circuited, the voltage generated between the first winding 16 of the choke coil type ballast 15 is stepped down so that the voltage generated at the third winding 18 becomes almost equal to the power supply voltage. , 1st
By setting the turns ratio of the winding and the third winding, each circuit that constitutes the triac conduction phase angle control device used in the low-pressure discharge lamp lighting device shown in FIG. 1, which does not use a step-up transformer, can be Since it can be used as is, the voltage is low, and it is completely insulated from the secondary high voltage circuit, each circuit making up the conduction phase angle control device can be operated safely.

Also, when starting the discharge lamp, the second winding 1 of the ballast 15
If the turn ratio of the second winding 17 is selected so that the voltage generated at the terminal 7 is close to the power supply voltage, the withstand voltage of the triax 20 can be lowered to about 400 V, resulting in low withstand voltage and large current. An inexpensive triax can be used.

Other advantages of this embodiment over the conventional apparatus shown in FIGS. 1 and 2 are as follows. That is, in the conventional device shown in FIGS. 1 and 2, the bypass reactor 5
is constructed so that only enough current to suppress the restriking voltage of the high-pressure discharge lamp 4 flows, so that most of the lamp current flows through the triax 2. Therefore, once the triac 2 fails and the parallel circuit of the bypass reactor 5 is opened, the high pressure discharge lamp 4 will be in a non-lighting state.

On the other hand, in the present embodiment shown in FIG.
7, the first winding 16
The impedance of the first winding 16 is adjusted so that about 40% of the rated lamp current flows through the first winding 16, and the triax 20 is made conductive.
By reducing the impedance of the winding 16 and increasing the rated lamp current by the remaining 60%, setting the rated lamp current to flow through the first winding 16 during normal operation will allow the rated lamp current to flow through the first winding 16 even if the triac fails. Even if the triack circuit is turned off, the discharge lamp 19
The light will be dimmed to 40%, and this state will be maintained and the light will not turn off.

In addition, in order to be able to supply constant power when dimming by 60%, when the second winding 17 of the ballast 15 is in the open state, the first winding 16 must be supplied with at least 40% of the rated lamp current. It is necessary to design it so that current flows through it. Therefore, if the design is made so that about 40% of the rated lamp current flows through the first winding when the second winding 17 is open as described above, the conduction phase angle of the triax 20 will be determined by the power supply voltage and ballast. Since it is controlled to supply constant power according to the voltage detected by the voltage detection circuit 22,
Constant power lighting can be performed with approximately 60 to 100% dimming.

In addition, if the setting is made so that 40% of the rated lamp current flows through the first winding when the second winding is opened as described above, even if the operation of the triax 20 becomes temporarily unstable, the first winding Since 40% of the rated lamp current flows through the winding 16, the third winding 18, which is closely magnetically coupled to the first winding 16, is used to control the conduction phase angle of the triax 20. The zero cross point can be detected reliably, and the lighting device can be operated stably.

Furthermore, in the conventional device shown in FIGS. 1 and 2,
If the conduction phase angle of the lamp current is controlled to be 60° or more, the luminous efficiency of the discharge lamp will decrease and flicker will increase, making it unusable. On the other hand, in this embodiment, it is possible to configure the first winding so that a current of 40% or more of the rated lamp current flows.
Phase control can be performed over the entire 180° range,
Variations in the chain coil type ballast and the conduction phase angle control circuit of the triac can be easily adjusted.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, even when lighting a discharge lamp in a high-voltage circuit, a current control triax for supplying constant power to the high-pressure discharge lamp, and a Each circuit that constitutes the conduction phase angle control means of the triac is as follows:
All can be operated at low pressure, and conventional low-voltage triaxes and their control means can be used as they are, making it possible to provide an inexpensive and highly reliable constant power discharge lamp lighting device.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a configuration example of a conventional constant power discharge lamp lighting device, and FIG. 2 is a block circuit diagram of a configuration example of a conventional high voltage constant power discharge lamp lighting device. Figure 3 is a block circuit diagram of an embodiment of the constant power discharge lamp lighting device of the present invention, and Figure 4A.
is a plan view of a chiyoke coil type ballast applied to the device shown in FIG. 3, and FIG. 4B is a plan view of the X in FIG. 4A.
FIG. 3 is a cross-sectional view taken along the −X′ line. In the figure, 11 is a power supply, 12 is an isolated step-up transformer, 15 is a chiyoke coil type ballast, 16 is a first winding, 17 is a second winding, 18 is a third winding, 1
9 is a discharge lamp, 20 is a triax, 21 is a lamp current zero cross detection circuit, 22 is a ballast voltage detection circuit, 23 is a power supply voltage detection circuit, 24 is a comparison pulse generation circuit, 31 is a three-leg iron core, and 32 is a gap. shows.

Claims (1)

[Scope of Claims] 1. An insulated step-up transformer with an AC power source connected to its primary winding, and three windings magnetically coupled, the first winding being connected to the secondary winding of the step-up transformer. a high-pressure discharge lamp connected to the secondary winding of the step-up transformer in series with the first winding of the ballast, which produces a low lamp voltage at startup, and a second winding of the ballast. a bidirectional switching element connected to a third winding of the ballast for controlling the current flowing through the first winding to control the power supplied to the high pressure discharge lamp; 3
A ballast voltage detection circuit that detects the voltage generated in the winding, a power supply voltage detection circuit connected to the power supply, and a voltage detection signal from the ballast voltage detection circuit and the power supply voltage detection circuit are input, and the high voltage discharge When starting the lamp, a drive pulse with a conduction phase angle set according to the voltage detection signal from the ballast voltage detection circuit is output to the bidirectional switching element, and after starting the high pressure discharge lamp, the lamp voltage reaches a predetermined value. After detecting from the voltage detection signal from the ballast voltage detection circuit that the ballast voltage has been reached, a drive pulse with a conduction phase angle set according to the voltage detection signal from the power supply voltage detection circuit is applied to the bidirectional switching element. and a comparison pulse generation circuit that outputs a comparison pulse, the conduction phase angle of the bidirectional switching element being controlled by the drive pulse from the comparison pulse generation circuit to supply constant power to the high pressure discharge lamp. A constant power discharge lamp lighting device characterized by: 2. A zero-cross detection circuit connected to the third winding of the ballast to detect a zero-cross point of the lamp current of the high-pressure discharge lamp from the voltage generated in the third winding and output a synchronizing signal, The constant power discharge lamp lighting device according to claim 1, wherein a synchronization signal is input to the comparison pulse generation circuit, and the drive pulse is output in synchronization with the synchronization signal. . 3 The first winding and the second winding of the ballast are arranged at a distance from each other on the iron core leg so that leakage magnetic flux is generated between them, and the current flowing through the second winding is connected to both of the windings. The lamp current flowing through the first winding is indirectly controlled by controlling with a directional switching element. Power discharge lamp lighting device. 4. The lamp current flowing through the first winding when the bidirectional switching element connected to the second winding of the ballast is non-conducting is 40 to 40% of the rated lamp current.
70%, and by changing the conduction phase angle of the bidirectional switching element in the range of 0 to 180° and controlling the lamp current in normal conditions so that it is always close to the rated current, it can be used as a high-pressure discharge lamp. A constant power discharge lamp lighting device according to claim 1 or 2, characterized in that a constant power is supplied. 5. A space is provided in the iron core leg portion where the first winding of the ballast is arranged, and when the bidirectional switching element is non-conductive, the lamp current flowing through the first winding is set to 40 to 70% of the rated value. 5. The constant power discharge lamp lighting device according to claim 4, wherein the constant power discharge lamp lighting device is set to .