JPH0261119B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a discharge lamp lighting device for preheating a discharge lamp, and particularly to dimming lighting.

[Background Art] A new dimming method is disclosed in Japanese Patent Application No. 113720/1983 filed by the present applicant. A specific circuit diagram of this discharge lighting device is shown in FIG. This circuit is a half-bridge type inverter circuit, which receives a DC power supply E as an input, and is composed of capacitors C ₁ , C ₂ , diodes D ₁ , D ₂ , and main transistors Q ₁ , Q ₂ , and a chiyoke coil L as a load. ₁ , the discharge lamps LA are connected in series, and the lamps LA
A capacitor _C3 is connected in parallel to form a series resonant circuit. Main transistors Q ₁ , Q ₂
The drive transformer is located at the base as the feedback input of the
The feedback signal obtained by T ₁ is added. Furthermore, sub-transistors Q ₃ and Q ₄ are connected between the base emitters of main transistors Q ₁ and Q ₂ , and their control is performed by using a dimming switch to control the output of a current transformer T ₂ that detects the lamp current Ila.
This is done by applying voltage to each base via SW ₁ and SW ₂ . The dimmer switches SW ₁ and SW ₂ are for switching between full lighting and dimmed lighting, and the dimmer switches SW ₁ and SW ₂ are turned on and off at the same time. All lights will be on. Note that the drive transformer T ₁ constitutes a first reactance element, and the capacitor C ₃ constitutes a second reactance element.

In the above configuration, when the switches SW ₁ and SW ₂ are off, that is, when the lights are all on, the circuit maintains the lighting state at a certain frequency, as shown in FIG. 4a. In the figure, I _Q1 and I _Q2 are each main transistor Q ₁ ,
The collector currents of Q ₂ , I _D1 and I _D2 are each diode D ₁ ,
is the current flowing through D ₂ . Here switch SW ₁ ,
When SW ₂ is turned on to enter the dimming state, the current transformer is turned on during the on period of main transistor Q ₁ .
A current is supplied from the secondary winding _n22 of _T2 to _{the sub-transistor Q3 via} the diode D3, and the sub-transistor _Q3 is turned on. Therefore, the base current of the main transistor _Q1 that had been flowing until now is cut off,
At the same time, the charge stored in the stray capacitance between the base and emitter of the main transistor _Q1 flows to the sub-transistor _Q3 , so that the main transistor _Q1 is rapidly turned off. Similarly the other main transistor Q ₂
Even during the on-period, the main transistor Q ₂ is rapidly turned off due to the sub-transistor Q ₄ being turned on. As a result, as shown in FIG. 4b, the oscillation frequency of the inverter circuit becomes higher than in the case of full lighting as shown in FIG. 4a, and the impedance of the inductive load increases to perform dimming. Figure 4c shows this state in more detail digitally, and Figure 4c shows the main transistor in a state where switches SW ₁ and SW ₂ are off, that is, when all lights are on.
Indicates the on/off status of _Q1 , and B indicates the switch.
Sub-transistor at the moment SW ₁ and SW ₂ are turned on
Indicates the on/off state of _Q3 . When the sub-transistor _Q3 is turned on, the main transistor _Q1 is turned off after a delay of τ. For this purpose, the main transistor Q ₁ ,
The on-off period of Q ₂ becomes shorter as shown in C, but at this time, since the on-signal of the sub-transistors Q ₃ and Q ₄ is obtained from the lamp current, the on-off period of the sub-transistors Q ₃ and Q ₄ also becomes shorter. As shown in (c), this is synchronized with the on/off cycles of the main transistors Q ₁ and Q ₂ . Therefore, in the dimming state, the oscillation frequency becomes high as shown in Figure b. Note that the section of τ above is the main transistor Q ₁ , Q ₂
This means the period between the storage time and the fall time until the switch turns off.

Furthermore, why when the main transistor Q ₁ is on, the sub-transistor Q ₃ is turned on, and also the main transistor Q ₂
We will explain whether sub-transistor _Q4 turns on with a delay when Q4 is on. Regarding main transistor _Q2 , when it is on,
The base signal of the main transistor _Q2 is the driving transformer
This is obtained by a current flowing through the primary winding _n11 of _T1 , and the switching of the main transistor _Q2 is determined by the sign of this current. At this time, the sub transistor
The signal to turn on Q ₄ is obtained from winding n ₂₃ of current transformer T ₂ . In this circuit, as mentioned above, when the main transistor Q ₂ is on,
The winding method of current transformer T ₂ is determined so that sub-transistor Q ₄ is also turned on. At this time, considering the phase of the current in the drive transformer T ₁ and the current transformer T ₂ , if the main transistor Q ₂ is on, the current flowing is from the DC power supply E to the capacitor.
C ₁ → Lamp LA and capacitor C ₃ → Chiyoke coil L ₁ → Primary winding of drive transformer T ₁ n ₁₁ → Discharge loop of main transistor Q ₂ and capacitor C ₂ (Capacitor C ₂ → Lamp LA and capacitor C ₃ → Chiyoke coil L ₁ → main transistor Q ₂ ) current.
Here, a combined current of the current flowing through the lamp LA and the current flowing through the capacitor _C3 flows through the primary winding _n11 of the drive transformer _T1 . for that,
The phase of the current flowing through the primary winding n ₁₁ of the drive transformer T ₁ is more advanced than that of the primary winding n ₂₁ of the current transformer T ₂ which takes the lamp current. For this reason, a signal is obtained that turns on the sub-transistor _Q4 with a delay after the main transistor _Q2 turns on, resulting in a signal as shown in C of FIG. 4C.

Next, as another conventional example, there is a circuit as shown in FIG. 5 as an example of a new dimming method disclosed in Japanese Patent Application No. 60-113716. It has a DC power supply E as an input, and is composed of a starting circuit 4 consisting of diodes D ₁ , D ₂ , main transistors Q ₁ , Q ₂ , a resistor R, a capacitor C, and a trigger element Z such as a diagonal, and a choke coil as a load. L ₁ and discharge lamp LA are connected in series, and a capacitor C ₃ is connected in parallel to lamp LA, thereby forming a series resonant inverter circuit. Further, a feedback signal obtained by the drive transformer _T1 is applied to the bases of the main transistors _Q1 and _Q2 . Furthermore, the base of the main transistor _Q2
A sub-transistor _Q4 is connected between the emitters.
Its on/off control is performed using a current transformer _T2 that detects the lamp current in the same way as shown in the flexible example above.
depends on the signal of the secondary winding n ₂₂ .

The switch SW ₂ is for dimming, and is _closed during dimming. Furthermore, when this switch SW ₂ is closed, that is, during dimming, the winding method of the current transformer T ₂ is determined so that the on signal of the sub-transistor Q ₄ is obtained during the period when the main transistor Q ₂ is on. ing. This operation is the same as that of the conventional example described above, so a description thereof will be omitted. Therefore, during dimming, the main transistor
The on period of Q ₂ is shorter than the on period of main transistor Q ₁ . If this is shown digitally, the 6th
It will look like the figure. Figure 6a shows the dimmer switch SW ₂
Fig. 6b shows the on period of _the main transistors Q ₁ and _{Q 2 during} dimming when the dimming switch SW ₂ is on. . As shown below, in this circuit, by making the on-periods of the main transistors Q ₁ and Q ₂ unbalanced, the DC component is cut off by the capacitor C ₁ , and the main transistor Q, which has no DC component, is used in the lamp LA. A smaller current flows through the lamp LA when _{Q 1} and Q ₂ are on for the same period. The principle of this dimming is described in detail in Japanese Patent Application No. 113716/1983.

However, in the two conventional examples shown above, when the lamp is a fluorescent lamp that requires preheating, the following problems occur. In general, in the case of fluorescent lamps that require preheating, it is better to apply a high voltage to the lamp after preliminary preheating due to issues such as lamp life. As shown in FIGS. 3 and 5 of the conventional example, when a fluorescent lamp has preheating,
Figure 3 shows a switch connected in parallel to lamp LA.
In FIG. ₅ , the switch SW ₃ , which is similarly connected in parallel to the lamp LA, is closed for a certain period of time after the power is turned on, and then opened to light the lamp LA. Note that the circuit in which the switch SW ₃ is closed for a certain period of time after the power is turned on and then opened is omitted. However, when explaining Figure 5,
After the power is turned on, the starting circuit 4 starts an oscillation circuit and the preheating switch SW ₂ is closed for a certain period of time. The power flowing at this time is, when the main transistor Q is on, the positive terminal of the DC power supply E → the capacitor C ₁ → one filament f ₁ of the lamp A → the preheating switch SW ₃ →
The other filament f ₂ of the lamp LA → the primary winding n ₂₁ of the current transformer T ₂ → the choke coil L ₁ → the primary winding n ₁₁ of the drive transformer T ₁ → the main transistor Q ₂
→ In the path of the negative pole of the DC power supply E, and when the main transistor Q ₁ is on, _{the capacitor C 1 →} the main transistor Q ₁ → the drive transformer T ₁ Secondary winding n ₁₁ → Primary winding coil L ₁ → Primary winding of current transformer T ₂ n ₂₁ → One filament of lamp LA f ₂ → Preheating switch SW ₃ → Other filament of lamp LA
Current flows in the path f ₁ → capacitor C ₁ , and while the preheating switch SW ₃ is closed, the resistance of filaments f ₁ and f ₂ is considered to be very small, so almost no current flows through capacitor C ₃ . Not flowing.
Therefore, the current flowing through the primary winding n ₁₁ of the drive transformer T ₁ and the current flowing through the primary winding n ₂₁ of the current transformer T ₂ are almost equal in phase and magnitude. As a result, in the dimming mode when dimmer switch SW ₂ is on, the main transistor is
The base signal that turns on Q ₂ and the sub-transistor Q ₄
The base signals that turn on will have the same phase. Therefore, when the main transistor Q ₂ tries to turn on, the sub-transistor Q ₄ also tries to turn on, resulting in a problem that oscillation stops during preheating. Similarly, in the circuit shown in Figure 3, when the main transistor Q ₁ is about to turn on, the sub transistor Q ₃ also turns on, and if the dimmer switches SW ₁ and SW ₂ are on during preheating, the oscillation will stop. There is a problem.

[Object of the Invention] The present invention has been provided in view of the above-mentioned points, and provides a discharge lamp that requires preheating, which can be sufficiently preheated in both full lighting and dimming without stopping oscillation. The present invention provides a discharge lamp lighting device for the purpose of.

[Disclosure of the Invention] (Structure) The present invention provides a feedback input blocking means that blocks feedback input to the sub-switching element in conjunction with the ON operation of the preheating switch element during preheating, regardless of full lighting or dimmed lighting. By providing the feedback input blocking means, the feedback input to the sub-switching element is blocked during preheating, so that full lighting and adjustment can be performed without stopping the oscillation of the main switching element by detecting the phase of the current. The feature is that sufficient preheating can be performed regardless of whether the light is turned on or not.

Example 1 An example of the present invention will be described below with reference to the drawings. In the conventional example, the switch for dimming (in Fig. 3
The opening and closing of SW ₁ and SW ₂ (SW ₂ in Fig. 5) was determined only by full lighting or dimming, but in the present invention, in addition to the above conditions, the dimming signal is always transmitted during preheating. This means setting the dimmer switch so that there is no light.

FIG. 1 shows an example in which the present invention is implemented in a series type inverter circuit. In Figure 1, the inverter circuit corresponds to the conventional one in Figure 5, and a transistor is installed in the dimmer switch _SW2 in Figure 5.
Q ₅ is used, contact r of relay Ry is used for preheating switch SW ₃ , and control circuit 3 for advance preheating is configured as a circuit for controlling relay Ry. These transistor _Q5 relay Ry, contact r of relay Ry, control circuit 3 for advance preheating, etc. constitute feedback input blocking means. Transistor _Q5 as a dimmer switch ( _SW2 ) is a transistor
A control circuit 3 that controls the contact r of the relay Ry connected between the base and emitter of Q ₄ and used as a preheating switch (SW ₃ ) connects the DC power source E to a resistor.
A monostable oscillation circuit is configured using a timer circuit IC1 (for example, μPC1555C manufactured by NEC) using the voltage divided by _R1 and _R2 as a power source. The operation of this monostable oscillator circuit is as follows: If the voltage divided by the resistors R ₁ and R ₂ is e, then when a voltage of (1/3) e or less is applied to the pin of the timer circuit IC1, the output terminal pin goes high. In this state, capacitor _C6 starts charging through low resistance _R4 , and when the capacitor _C6 is charged until the potential reaches (2/3)e, the pin of timer circuit IC1 becomes It becomes “ON” state and inverts the output terminal pin to L level.
At this time, the charge charged in the capacitor _C6 at the same time is discharged through the pin, and the timer circuit IC is discharged again.
When a pulse of (1/3)e or less is input to pin 1, the same operation is repeated.

In this circuit, the output of the monostable oscillator circuit is
One is transistor Q ₆ that operates relay Ry.
The other is connected to the base of transistor _Q5 , which is used as a dimmer switch.
Further, the all-lighting/dimming mode switching circuit 2 connected to the control circuit 3 via the diode _D7 outputs a signal for all lighting (H level) or a signal for dimming (L level). Furthermore, the dimmer switch mentioned here is a switch that determines whether the light is turned on substantially fully or dimmed. Furthermore, relay
Contact r of Ry is used in a normally open state in this embodiment.

Next, the operation of this embodiment will be explained. First, when the power is turned on, the inverter circuit starts oscillating by the starting circuit 4, and at the same time, the pin of the timer circuit IC1 is initially at L level to control the relay Ry, so a trigger is applied, and the signal at the output terminal pin becomes H level. Become. In response, transistor Q ₆ turns on, excitation current flows through relay Ry, and contact r closes. Further, the output signal from the pin of the timer circuit IC1 turns on the transistor _Q5 regardless of the H level or L level signal of the full lighting/dimming mode switching circuit 2. Therefore, the signal of the secondary winding n ₂₂ of the current transformer T ₂ is not transmitted to the sub-transistor Q ₄ and is always in an off state. As described above, after the power is turned on, preheating is performed for a certain period of time regardless of the full lighting/dimming switching signal from the full lighting/dimming mode switching circuit 2. After that, the pin of the output terminal of timer circuit IC1 goes low.
When the level is reached, transistor Q ₆ turns off, relay Ry is not driven, contact r returns and opens, and sub-transistor Q ₄ is turned on/off by all lighting/dimming mode switching circuit 2. It depends on the optical switching signal. In the case of full lighting, transistor Q ₅ remains on and sub-transistor Q ₄ is always turned off.
In the case of dimming lighting, by turning off the transistor _Q5 and applying the current flowing through the primary winding _n21 of the current transformer _T2 to the sub-transistor _Q4 ,
During the on period of the main transistor _Q2 , the secondary transistor
Light control is performed by turning on _Q4 and forcibly shortening the on period of main transistor _Q2 .

As described above, during the preheating period, the sub-transistor _Q4 is always turned off regardless of the full lighting/dimming switching signal from the full lighting/dimming mode switching circuit 2, so that dimming is possible even in the full lighting mode. Even in the mode, after preheating by turning on the power, each lighting state can be changed. In this embodiment, the transistor _Q5 is used as a method for determining whether or not to transmit the signal from the current transformer _T2 to the sub-transistor _Q4 , and the on/off signal of the transistor _Q5 is transmitted to the preheating switch (contact r). The close signal and the full lighting/dimming mode switching signal from the full lighting/dimming mode switching circuit 2.
Although an OR is used, a separate switch may be provided in place of transistor _Q5 , and the switch may be placed anywhere as long as it does not transmit the signal from current transformer _T2 to sub-transistor _Q4 during preheating. good.

Embodiment 2 FIG. 2 shows another embodiment, which solves the drawbacks of the conventional circuit shown in FIG. In Figure 2, NAND gates G ₁ , G ₂ , resistors R ₅ , R ₆ , and capacitors
A monostable oscillation circuit 5 is composed of C ₇ , C _{8 ,} etc.
Switches SW ₁ and SW ₂ are controlled to switch to full lighting and dimming mode by signals from full lighting/dimming mode switching circuit 2 via transistor Q ₇ and relay Ry ₂ , and are turned off and off in full lighting mode. It is set to turn on in dimming mode. Also,
During preheating, a preheating switch _SW3 and a switch _SW4 such as relay contacts are set to be closed by a relay _Ry1 .

The operation is the same as in the above embodiment, and during preheating, transistor Q ₆ is always turned on, relay Ry ₁ is driven, switches SW ₃ and SW ₄ are closed, and current transformer T ₂ is connected to sub-transistors Q ₃ and Q _4. When not preheating, current transformers are connected to sub-transistors Q ₃ and Q ₄ .
Whether or not to transmit the signal from _T2 is determined by the full lighting/dimming mode switching signal from the full lighting/dimming mode switching circuit 2. During dimming lighting, switches SW ₁ and SW ₂ are on, a signal from current transformer T ₂ is given to sub-transistors Q ₃ and Q ₄ , and the period when each main transistor Q ₁ and Q ₂ is on is The light is dimmed by forcibly shortening the time.

[Effects of the Invention] As described above, the present invention includes a DC power supply, a pair of main switching elements connected in series to both ends of the DC power supply and turned on and off alternately, and a switch connected in parallel to the feedback input terminal of at least one main switching element. a parallel circuit of a discharge lamp and a second reactance element connected to both ends of at least one of the main switching element via a first reactance element, and a discharge lamp connected in parallel to the secondary switching element; a preheating switch element for preheating the filament prior to application of a voltage; a parallel circuit between the discharge lamp and the preheating switch element; and the second preheating switch element.
a current transformer inserted between the first reactance element and the second reactance element, the secondary output of the first reactance element is input to the feedback input terminal of the main switching element, and the secondary output of the current transformer is input to the feedback input terminal of the main switching element. In a discharge lamp lighting device in which the discharge lamp is dimmed by feedback input to the control end of the discharge lamp, the sub-switching is performed in conjunction with the ON operation of the preheating switch element during preheating, regardless of full lighting or dim lighting. Since a feedback input blocking means for blocking feedback input to the element is provided, the feedback input blocking means blocks feedback input to the sub-switching element during preheating, and the phase of the current is detected. This allows sufficient preheating to be performed without stopping the oscillation of the main switching element, regardless of whether the device is fully lit or dimmed. Therefore, even when the power is turned on in dimming mode, almost no additional circuitry is required. This has the effect that it is possible to proceed from preheating to dimmed lighting without any problem.

[Brief explanation of the drawing]

Fig. 1 is a specific circuit diagram of one embodiment of the present invention, Fig. 2 is a specific circuit diagram of an embodiment of the present invention;
The figure is a specific circuit diagram of another conventional example same as the above, FIG. 3 is a specific circuit diagram of the conventional example, and FIG.
FIG. 5 is a specific circuit diagram of another conventional example, and FIG. 6 is an explanatory diagram of the same operation. Q ₁ and Q ₂ are main transistors, Q ₃ and Q ₄ are sub transistors, and T ₂ is a current transformer.

Claims (1)

[Claims] 1. A DC power supply, a pair of main switching elements connected in series to both ends of the DC power supply and turned on and off alternately, a sub-switching element connected in parallel to the feedback input terminal of at least one main switching element, and the main switching element. A parallel circuit of a discharge lamp and a second reactance element connected to both ends of at least one of the elements via the first reactance element, and a parallel circuit connected in parallel with the discharge lamp for preheating the filament prior to voltage application. a preheating switch element; a current transformer inserted between a parallel circuit of the discharge lamp and the preheating switch element; and the second reactance element; In the discharge lamp lighting device, the discharge lamp is dimmed by inputting it to the feedback input terminal of the main switching element and feedback inputting the secondary output of the current transformer to the control terminal of the sub-switching element. 1. A discharge lamp lighting device comprising a feedback input blocking means for blocking feedback input to the sub-switching element in conjunction with the ON operation of the preheating switch element during preheating, regardless of whether the light is lit or not.