JPH0433300A - Turn-on device for discharge lamp - Google Patents

Abstract

PURPOSE:To prevent the occurrence of flame failure of a high-pressure discharge lamp at the time of a start by setting the load characteristic of a lighting circuit to the full-lighting state for a start immediately after a power source is turned on if the dim-lighting mode is selected, and gradually changing the load characteristic to the dim-lighting state while maintaining the tube power nearly constant when the tube power nearly reaches the stable lighting state. CONSTITUTION:The Zener voltage of a Zener diode ZD1 is set so that the Zener diode ZD1 is excited to start the reduction of the current flowing in a bidirectional thyristor Q1 when the lighting state of a high-pressure discharge lamp DL, on the load characteristic in the full-lighting state nearly reaches the stationary lighting power in the dim-lighting state after the high-pressure discharge lamp DL is started before the high-pressure discharge lamp DL is changed to the stationary full-lighting state. When the Zener voltage of the Zener diode ZD1 is thus set, the starting process of the high-pressure discharge lamp DL is moved from the point FS to the point FL0 on a solid line BF as shown by an arrow (1), then it is gradually moved from the point FL0 to the point DM as shown by the arrow (2) by the action of a transistor Q2 while the tube power is kept constant, and the stable dim-lighting state is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a discharge lamp lighting device that can perform stepwise dimming.

[Conventional technology]

FIG. 5 shows a circuit diagram of a discharge lamp lighting device that can perform stepwise dimming. In Fig. 5, ■1 is an AC power supply, Ll,
L2 is an inductance element, and DL is a high-pressure discharge lamp, which form a main lighting circuit.

Sl is a contact of the dimming relay RY1, and its opening/closing state is set so that when the contact S1 is turned on, the full lighting mode is set, and when the contact S1 is turned off, the dimming lighting mode is set.

V is 1 tB for generating a dimming command, and the dimming control switch S
, the dimming relay RY is turned on (when turned on).

is set so that the contact S1 is turned off when the contact S1 is excited.

FIG. 6 shows the main characteristics of the discharge lamp lighting device shown in FIG. In FIG. 6, the vertical axis is the voltage V, and the horizontal axis is the current I. Real & iBF is in full lighting mode, i.e. contact S1
The solid line BD is the load characteristic of the lighting circuit when the contact S1 is turned on, and the solid line BD is the load characteristic of the lighting circuit when the contact S1 is turned off. The solid line A1 is the characteristic of the high-pressure discharge lamp DL itself when it is stably lit.

Therefore, in the discharge lamp lighting device of FIG. 5, in the full lighting mode, the high pressure discharge lamp DL is between the solid line BF and the actual kg
A stable lighting state is achieved at the intersection FL with At. In addition, in the dimming lighting mode, the high-pressure discharge lamp DL is indicated by the solid line B
A stable lighting state is reached at the intersection DM of D and the solid line A1.

V, , V, , IF, and Iゎ indicate the tube voltage and tube current during stable lighting in the above-mentioned full lighting mode and dimming lighting mode, respectively.

[Problem to be solved by the invention]

The discharge lamp lighting device shown in Fig. 5 basically operates as described above, but there is a desire to light the high-pressure discharge lamp DL in dimming lighting mode immediately after turning on the AC power supply ■1. , Various methods have been considered for this purpose.

The simplest method is to turn on the dimming control switch SD at the same time as turning on the AC power supply ■1.The load characteristics of the lighting circuit in that case are shown by the solid line BD in Figure 6. Therefore, the operating point of the high-pressure discharge lamp DL moves from point DS to point DM as shown by the solid arrow, and the AC power supply ■1
The high pressure discharge lamp DLO tube current I immediately after turning on is:
In FIG. 7 (a reprint of FIG. 6), at point DS, the current is ■. flows. As is clear from FIG. 7, this current ID3 has a value significantly smaller than the current trs at the point FS flowing through the high-pressure discharge lamp DL immediately after the AC power supply V1 is turned on in the load characteristics of the lighting circuit in all lighting modes. It has become. For this reason, if the high-pressure discharge lamp DL is started and lit with the load characteristics of the lighting circuit in the dimming lighting mode immediately after the AC power supply ■1 is turned on, the temperature of the arc tube of the high-pressure discharge lamp DL will rise because the electric firmes are small. The disadvantage is that it is slow and takes an extremely long time to reach point DM.

That is, there is a problem in that it takes a long time for the high pressure discharge lamp DL to reach the dimmed luminous flux after the AC power source (1) is turned on.

Next, as a possible method, even if there is a desire to turn on the light in dimming lighting mode immediately after turning on the AC power supply (1), in order to solve the above-mentioned difficulty that it takes a long time to achieve dimming luminous flux, Immediately after turning on the AC power supply v1, the lighting circuit operates with the load characteristics of the full lighting state, and the high pressure discharge lamp D
In this method, the operating point of L is moved from point FS on solid line BF, and after reaching at least point FL, the load characteristics of the lighting circuit are switched to the load characteristics of the dimmed lighting state (solid line BD).

Figure 8 shows the behavior of the high pressure discharge lamp DL in that case.
That is, in the dimming lighting mode, after the AC power supply v1 is turned on, the dimming control switch S is turned on. When the high-pressure discharge lamp DL is started, the load characteristics of the lighting circuit are temporarily set to the full lighting state. As a result, the operating point of the high-pressure discharge lamp DL becomes point FS immediately after the AC power source 1 is turned on, and a current IFS flows through the high-pressure discharge lamp DL. after that,
The operating point of the high-pressure discharge lamp DL moves from the point FS on the solid line BF along the solid line arrow ■, and the lighting state changes accordingly. Then, the point FL is reached after a certain period of time has elapsed.

Furthermore, at least the operating point of the high pressure discharge lamp DL is point F.
After reaching L, by turning on the dimming control switch SD, the operating point of the high-pressure discharge lamp DL instantly moves to point DM0 on the solid line BD, as shown by the broken arrow ■, and then As shown by the solid line arrow ■, it moves to the point DM on the solid line BD and enters a stable lighting state in the dimming lighting mode.

Here, the reason why the operating point of the high-pressure discharge lamp DL moves to the point DM instead of the point DM will be explained. This is because in the lighting state at point FL, the pressure inside the arc tube of the high-pressure discharge lamp DL is higher than the pressure inside the arc tube at point DM, and if only the load characteristic is switched to the solid line BD in this state, the light emission Voltage V and current on solid line BD according to pipe pressure! This is because the operating point moves to the point of the combination of , and that point is the point DM0 mentioned earlier. - When fishing on a boat, when switching suddenly from full lighting to dimmed lighting as described above, the tube voltage increases once, the tube current suddenly decreases,
After that, the tube voltage decreases and the tube current increases.

Note that such an operation can be easily achieved by combining the dimming relay RY1 with a delay timer or the like, so a specific example of the means for achieving this is omitted.

The method shown in FIG. 8 above allows a large current to flow during the starting process of the high-pressure discharge lamp DL, so compared to the method shown in FIG. It becomes possible to shorten the time required to achieve the dimming luminous flux until reaching a certain point DM.

However, as can be seen from FIG. 8, the operating point passes through point DM immediately after switching from solid line BF to solid line BD, so in the process from point FS to point DM, the tube voltage of high-pressure discharge lamp DL increases. Although it was instantaneous, it caused a high
This may cause the high pressure discharge lamp DL to go out.

On the other hand, if a solid line BD is designed so that it is difficult for the light to fade out, there are design difficulties such as the need to reduce the dimming ratio.

In addition, when switching the load characteristics of the lighting circuit, the high pressure discharge lamp D
The current flowing through L suddenly decreased, which could have an adverse effect on peripheral equipment.

An object of the present invention is to provide a discharge lamp lighting device that has a short time to achieve dimming luminous flux, can prevent a high-pressure discharge lamp from going out when starting in dimming lighting mode, and can reduce adverse effects on peripheral equipment. The goal is to provide the following.

[Means to solve the problem]

The discharge lamp lighting device of the present invention is capable of switching the lighting mode of the high-pressure discharge lamp between full lighting mode and dimming lighting mode, and when selecting the dimming lighting mode, the load characteristics of the lighting circuit are changed to full lighting immediately after power is turned on. the high-pressure discharge lamp is started, and when the tube power of the high-pressure discharge lamp substantially reaches the tube power of the stable lighting state in the dimming lighting mode, the load on the lighting circuit is reduced while maintaining the tube power substantially constant. The characteristics are gradually shifted from the full lighting state to the dimmed lighting state.

[For production]

According to the configuration of the present invention, when the dimming lighting mode is selected, the load characteristics of the lighting circuit are set to the full lighting state immediately after the power is turned on, and the high pressure discharge lamp is started, so that a large current flows into the high pressure discharge lamp immediately after the power is turned on. can flow, and the time to achieve dimming luminous flux is shortened.

In addition, when the tube power of the high-pressure discharge lamp reaches approximately the tube power of the stable lighting state in the dimming lighting mode, the load characteristics of the lighting circuit are changed from the full lighting state to the dimming lighting state while maintaining the tube power approximately constant. Because the transition is gradual, the tube voltage of the high-pressure discharge lamp does not increase when the load characteristics of the lighting circuit transition from the full lighting state to the dimmed lighting state. There is no sudden decline.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention. In FIG. 1, Ql is a bidirectional thyristor;
PC is a phase control circuit that controls the conduction angle of the bidirectional thyristor, and these are the dimming relay RY in Fig. 5.
, and contact S, in which the bidirectional thyristor Q1 is fully conductive in the full lighting mode, and in the dimming lighting mode, the bidirectional thyristor Q1 is completely cut off during stable lighting, and the starting in the dimming lighting mode is In the process, the bidirectional thyristor Q1 is initially fully conductive for a certain period of time;
After that, it is set to gradually shift from the fully conductive state to the completely cut-off state. The other configurations are the same as the conventional example shown in FIG.

FIG. 2 shows a circuit diagram of a specific example of the phase control circuit pc in FIG. 1. In FIG. 2, Tf is a transformer, DBL
, DB2 are full-wave rectifiers, R1 to R9 are resistors, C1 to C4 are capacitors, and IC
1 is a general-purpose timer integrated circuit (for example, μPCl manufactured by NEC)
555 etc.), C2 to Q are transistors, respectively.
D1D2 are diodes, and ZDl is a Zener diode.

FIG. 3 is a time chart of each part of the circuit of FIGS. 1 and 2, where (al indicates the voltage waveform of AC 1 tav1. Cb) is the reference voltage V5 existing inside the general-purpose timer integrated circuit IC1. and the voltage of the same terminal 6 ■6,
(C1 indicates the output voltage of the general-purpose timer integrated circuit IC1,
(dl indicates the state of the gate current flowing to the gate of bidirectional thyristor Q1, +81 indicates the state of the gate current flowing to the gate of bidirectional thyristor Q1
The waveforms (bl to fa) above are time charts for the full lighting mode. In addition, (fl is the reference voltage V5 existing inside the general-purpose timer integrated circuit IC1.
and the voltage V at the 6th terminal, (the phantom shows the output voltage of the general-purpose timer integrated circuit IC1, (the eye shows the state of the gate current flowing to the gate of the bidirectional thyristor Q1, and (
Reference numeral 11 indicates a current flowing through the bidirectional thyristor Q1, and the waveforms of if) to (1) above are time charts at a certain point in the starting process in the dimming lighting mode.

Next, the operation of the phase control circuit pc of FIG. 2 will be explained with reference to the time chart of FIG. 3.

When the AC power supply ■1 in the divination mode is turned on, the voltage changes to the transformer Tf,
After being lowered in voltage by a full-wave rectifier DB1, the voltage is full-wave rectified by a full-wave rectifier DB1 and applied to both ends of a series circuit of resistors R, , R2. Further, this voltage becomes a power supply voltage for driving the general-purpose timer integrated circuit IC1 and other circuit parts through the diode DI and the capacitor C1.

On the other hand, when the dimming control switch So is turned off in order to fully light up the high-pressure discharge lamp DL, no voltage is generated in the capacitor C4, so the transistor Q4 is turned off and the transistor Q5 is turned on, so that the transistor Q2 is turned off. becomes.

In this state, the voltage V at the No. 6 terminal of the general-purpose timer integrated circuit IC increases with a slope determined by the time constant of the resistor R4 and the capacitor C2.

In the above state, the voltage of the AC power supply (3rd
(see Figure +51)) is full-wave rectified by the full-wave rectifier DB, and divided by the resistors R1 and R, and the voltage is the voltage that is obtained by the general-purpose timer integrated circuit ■C
Since it is added to the 2nd terminal (reset terminal) of 1,
The general-purpose timer integrated circuit C1 is reset at time t0 of each half cycle of the voltage of the AC power source v1. After the reset, the output voltage of the general-purpose timer integrated circuit C1 (the voltage at the No. 7 terminal) becomes high level as shown in FIG. 3 (10).

On the other hand, the voltage v6 of the 6th terminal of the general-purpose timer integrated circuit IC
As shown in Figure 3 (bl), increases with a time constant due to resistor R4 and capacitor C2, and voltage
5 (at time 11 of each half cycle), the output voltage of the general-purpose timer integrated circuit IC becomes low level, as shown at +51 in FIG. As a result, at time t1, a gate current flows through the gate of the bidirectional thyristor Q through the resistor R8 as shown in FIG. A current without a rest section will flow. Therefore, the high-pressure discharge lamp DL is in a fully lit state in which the tube current is a current that is a combination of the current flowing through the series circuit of the bidirectional thyristor Q1 and the inductance element L2 and the current flowing through the inductance element L1.

In addition, in order to make the bidirectional thyristor Ql fully conductive as described above, before the current shown in Fig. 3 +51 is reversed, the gate current shown in Fig. 3 +d) is caused to flow through the bidirectional thyristor Q1. , it is necessary to set the time constants of resistor R4 and capacitor C2.

i Turn on the AC type @V1 in the divination mode, and turn on the dimming control switch So to dim the high-pressure discharge lamp DL, and the power supply ■. The voltage is full-wave rectified and smoothed by the full-wave rectifier DB2 and the capacitor C4, and a predetermined DC voltage is generated across the capacitor C4. Since this DC voltage is applied to the base of transistor Q4 via resistor R9, transistor Q4 is turned on, and therefore transistor Q3 is turned off. As a result, capacitor C3
When the voltage increases with the time constant of resistor R7 and capacitor C3 and exceeds the Zener voltage of Zener diode ZD1, transistor Q2 is turned on and resistor R6 is connected in parallel to capacitor C2. The time constant for the rise of the voltage v6 at terminal 6 of the general-purpose timer integrated circuit IC1 becomes sufficiently small compared to the fully lit state, and by the time the general-purpose timer integrated circuit IC1 is reset at time t1 of the next half cycle, the voltage v6 is the reference voltage ■.

, the output voltage of the general-purpose timer integrated circuit IC1 remains at a high level, and the bidirectional thyristor Q
No gate current flows through the bidirectional thyristor Q, and the bidirectional thyristor Q is completely cut off. Therefore, the high pressure discharge lamp DL
In this case, a dimming lighting state is entered in which only the current passing through the inductance element L1 flows as a tube current.

Note that it is easy to set the resistance value of the resistor R5 so that the voltage 6 does not exceed the reference voltage V by the next time t1.

Here, the starting process of the high pressure discharge lamp DL immediately after turning on the AC power supply V1 will be explained.

Light control switch S! Consider a dimming lighting mode in which AC power supply v1 is turned on with l turned on. ! Since the Ii light control switch SD is on, the transistor Q4 is on and the transistor Q8 is off. In this state, when AC power supply v1 is turned on, capacitor C3 starts charging through resistor R7, but transistor Q2 is in an off state until the voltage of capacitor C8 reaches approximately the Zener voltage of Zener diode ZD1. , operates in the same manner as the full lighting state described above, and starts as if in full lighting mode, that is, the bidirectional thyristor Q1
The high-pressure discharge lamp DL starts in a state where the lamp is fully conductive and goes into a stable lighting state.

Then, as time passes after the AC power supply V, the voltage of the capacitor C3 rises, and when its value exceeds the Zener voltage of the Zener diode ZD, a base current is gradually supplied to the base of the transistor Q2. start,
The transistor Q2 behaves as if it were a variable resistor, and is in a mode in which the time constant of charging the capacitor C2 through the resistor R4 gradually increases. A time chart showing a certain point in time in this state is shown in FIG. 3 (fl~+11).

At this point, the voltage obtained by full-wave rectification of the voltage of AC power supply v1 (see tal in Fig. 3) by full-wave rectifier DB1 and voltage division by resistors R1 and R2 is applied to the 2nd terminal of the general-purpose timer integrated circuit IC (
(reset terminal), the general-purpose timer integrated circuit IC1 is reset at time t0 of each half cycle of the voltage of the AC power source 1. After the reset, the output voltage (voltage at terminal 7) of the general-purpose timer integrated circuit IC becomes high level as shown in FIG. 3 (gl).

On the other hand, the voltage at pin 6 of the general-purpose timer integrated circuit IC is
As shown in FIG. 3 (fl), due to the time constant of resistors R4R5 and capacitor C2, the voltage rises at a gentle slope compared to the full lighting condition, and at the point when the voltage v6 exceeds the reference voltage V5 (
General purpose timer integrated circuit IC at time 12) every half cycle
As shown in Fig. 3 (phantom), the output voltage of
A gate current as shown in Figure 3 (river) flows through the gate of the bidirectional thyristor Q1 through resistor R8,
) flows, and the current flowing through the bidirectional thyristor Q1 is combined with the current flowing through the inductance element L1 to become the tube current of the high-pressure discharge lamp DL.

In this case, the tube current of the high-pressure discharge lamp DL shifts to a dimming lighting state because the rest period of the bidirectional thyristor Q1 becomes longer as time passes and the lamp is completely cut off.

In the above, the Zener voltage of the Zener diode ZD, before the high-pressure discharge lamp DL shifts to the steady lighting state of full lighting, and after the high-pressure discharge lamp DL has started, the Zener voltage of the Zener diode ZD, on the load characteristic (solid line BF) in the golden lighting state. The Zener diode ZD is set to conduct when the lighting state of the high-pressure discharge lamp DL substantially reaches the steady lighting power in the dimmed lighting state and starts throttling the current passing through the bidirectional thyristor Q1.

In this way, when the Zener voltage of the Zener diode ZD is set, the starting process of the high pressure discharge lamp DL is
It will not change as shown in the figure, but as shown in Figure 4. In other words, in Fig. 4, the tube power moves from point FS to point FL0 on the solid line BF as shown by the arrow (■) (the load characteristic in the fully lit state), and then, due to the action of the transistor Q2, the tube power continues to flow from point FLo as shown by the arrow (■). While maintaining the light constant, it gradually moves to point DM, resulting in a stable dimmed lighting state.

As described above, the discharge lamp lighting device of the embodiment shown in FIGS. 1 and 2 operates as shown in FIG. 8 in the dimming lighting mode, and at the initial stage of starting the high-pressure discharge lamp DL,
Since the operating point of the high-pressure discharge lamp DL moves on the load characteristics of the full lighting mode, the arc tube temperature of the high-pressure discharge lamp DL rises quickly, and furthermore, the point at which the tube power in the stable lighting state of the dimming lighting mode is almost reached. Since the operating point of the high-pressure discharge lamp DL is moved directly from FLo to point DM while keeping the tube power constant, the time to achieve dimming luminous flux is shorter than in the cases of Figs. 7 and 8, and Since the switching to the dimming lighting mode is performed before the pressure inside the arc tube increases, it is possible to avoid turning off the high-pressure discharge lamp DL due to a sudden increase in the tube voltage at the time of switching. Furthermore, the switching and the operating point of the high-pressure discharge lamp DL can be simultaneously performed without sudden changes, and it is also possible to avoid adverse effects on peripheral equipment due to a sudden decrease in current.

In the configuration shown in FIG. 2, the switching timing of the operating point of the high-pressure discharge lamp DL from the solid line BF to the solid line BD is determined by the charging time constant of the capacitor C8 after the AC power supply V1 is turned on and the Zener voltage of the Zener diode ZD. Although the combination is set, a configuration may also be adopted in which the voltage, current, force, etc. of the high-pressure discharge lamp DL are detected, and the switching timing is determined based on that.

〔Effect of the invention〕

According to the discharge lamp lighting device of the present invention, when the dimming lighting mode is selected, the load characteristics of the lighting circuit are set to the full lighting state immediately after the power is turned on, and the high pressure discharge lamp is started. A large current can be passed through the LED, and the time required to achieve dimming luminous flux can be shortened.

In addition, when the tube power of the high-pressure discharge lamp reaches approximately the tube power of the stable lighting state in the dimming lighting mode, the load characteristics of the lighting circuit are changed from the full lighting state to the dimming lighting state while maintaining the tube power approximately constant. Because the transition is gradual, the tube voltage of the high-pressure discharge lamp does not increase when the load characteristics of the lighting circuit transition from the full lighting state to the dimmed lighting state, which prevents the high-pressure discharge lamp from going out during startup. It can be prevented. Moreover, since the current in the lighting circuit does not suddenly decrease at that time, the adverse effect on peripheral devices can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention, Fig. 2 is a specific circuit diagram of the main part of Fig. 1, and Fig. 3 shows the circuit operation of Figs. 1 and 2. A time chart, Fig. 4 is an operating characteristic diagram of the discharge lamp lighting device shown in Fig. 1, Fig. 5 is a circuit diagram of a conventional discharge lamp lighting device, and Figs. 6, 7, and 8 are respective conventional examples. FIG. vl...AC power supply, DL...high pressure discharge lamp, PC
...phase control circuit, Q, ...bidirectional thyristor,
Three... Dimming control switch, L,, L2... Inductance element ↑ Fig. 4 4! Mar- ↑ Figure shi! D Figure 1゜F (1 [- ↑ Figure os FS t1- Meeting t1-

Claims (1)

[Claims] In a discharge lamp lighting device capable of switching the lighting mode of a high-pressure discharge lamp between a full lighting mode and a dimming lighting mode, when the dimming lighting mode is selected, the load characteristics of the lighting circuit are set to full lighting immediately after power is turned on. the high-pressure discharge lamp is started, and when the tube power of the high-pressure discharge lamp substantially reaches the tube power of the stable lighting state in the dimming lighting mode, the load on the lighting circuit is reduced while maintaining the tube power substantially constant. A discharge lamp lighting device characterized in that the characteristics gradually shift from a full lighting state to a dimmed lighting state.