JPH02201895A - Discharge lamp lighting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to use a device with a small capacity for a semiconductor switching device and lower the cost by keeping a lamp working condition in low lamp current state in transition stage to a short-circuited state from a lamp opened state immediately after lamp lighting start and suppressing a peak current. CONSTITUTION:Newly a lamp current switching circuit 3 is additionally installed in a common discharge lamp lighting circuit. With this structure and under the condition of setting a light modulation switch 4 to be in the whole lighting side and when an electricity is applied, a transistor 33 on the circuit 3 is turned on and a transistor 51 of a lamp current setting circuit 5 is turned off and the resistance ratio is set at high side as (R2+R3)/(R1+R2+R3). A lamp current thus becomes in the low side, that is in a light modulation state and starts discharge. However, the current becomes steady the transistor 51 of the circuit 5 is turned on and the resistance ratio is changed to low side as (R2)/R1+R2) and continues discharge while being in the highest lighting state. As a result, a switching device with a small capacity can be used as a light modulation switch.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a device for lighting a discharge lamp using a phase control element, a high frequency inverter, etc. , a discharge lamp (lamp) that takes a relatively long time from this short-circuit state to a steady lighting state.
The present invention relates to a discharge lamp lighting device suitable for use as a lighting device.

[Prior Art] Conventionally, as this type of device, one having the configuration shown in FIG. 2 is known. The device shown in the figure includes a lamp current detection circuit 1 and a PWM control circuit 2.
The lamp current IL of a high-pressure discharge lamp (not shown) is detected by the PWM control circuit 2, and an on/off duty pulse is generated according to the detected lamp current IL, thereby controlling the on/off state of a semiconductor switching element of a stabilizing circuit (not shown). By controlling based on this pulse, the lamp current (5) of the high pressure discharge lamp is stabilized.

With the negative feedback control described above, this discharge lamp is stably lit.

[Problems to be Solved by the Invention] However, in this device, when starting the high-pressure discharge lamp (lamp) by turning on the power, etc., a large peak value is generated in the semiconductor switching element of the stabilizing circuit, as shown in FIG. Therefore, a semiconductor switching element having a large capacity that can withstand this peak value must be used, which is disadvantageous in that it leads to an increase in cost.

For example, in a ZkW-class mercury lamp, this peak value reaches as high as 10-odd A, and the cost varies greatly depending on whether a semiconductor switching element with a maximum rated current of IOA or one with a higher current rating of 20 A is used.

Therefore, as disclosed in Japanese Utility Model Publication No. 55-8077, the pole conductor switching element of the stabilizing circuit is turned on to reduce the lamp current from the time the power is turned on until the steady lighting state is reached. - It is also possible to control the off-state state. However, if this is done, there is a problem in that it takes a relatively long time (starting time) from when the lamp starts lighting until the lamp light intensity increases and the lamp reaches a stable lighting state.

This invention has been made in view of the problems of the prior art, and suppresses the peak current during the transition period when the lamp changes from an open state to a short circuit state immediately after the lamp starts lighting, and shortens the starting time of the lamp. The purpose is to provide an electric light lighting device.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a detection circuit for detecting lamp power or lamp current of a discharge lamp, a semiconductor switching element, and an inductance element, and the output of the detection circuit is a stabilizing circuit that controls the on/off state of the switching element based on the lamp power or lamp current, and a stabilizing circuit that controls the on/off state of the switching element based on the lamp power or lamp current; The on/off state of the switching element is switched to a first state in which the lamp current is smaller, and the switching element is turned on/off in response to the power or current value exceeding a predetermined value.
It is characterized by comprising a switching means for switching the off state to a second state in which the lamp current is higher.

[Function] According to the above configuration, since the lamp current or power is O when the power is turned on, the switching element of the stabilizing circuit changes the on/off state to the first state where the lamp current is smaller due to the action of the switching means. It is set. Therefore, the lamp current ■.

changes as shown by the solid line in Figure 4, and the current flowing through the semiconductor switching element changes as shown by the solid line in Figure 3.
Peak current value can be suppressed. In the same figure, To is the timing when the power is turned on, T1 is the timing when the discharge starts, and from To to T
, it takes about 1 second. After the start of discharge, as the discharge state shifts from glow discharge to arc discharge, the lamp resistance shifts from a high resistance state to a short circuit state, and the lamp current rapidly increases. And this increase in lamp current,
Therefore, the power is detected by the detection circuit with a slight time delay, and this is fed back to the on/off state of the switching element to limit the lamp current (time T). T,
The time from T2 to T2 is approximately tooms. Further, when lamp current (or power) is detected, the switching means operates to switch the on/off state of the switching element of the stabilizing circuit to a second state in which the lamp current is larger (
At time T3), in this state, a nearly constant current (
or electric power) is supplied, the lamp is gradually heated, and the tube temperature, the pressure inside the tube, the lamp voltage, and the brightness increase, and a steady lighting state is reached (time T4). The time from T to T4 is shorter as the lamp current (and therefore power) is larger.
This invention aims to shorten the time from T3 to T4 by switching the lamp current to a larger value in the time after T3. The first state can be, for example, the same as the dimmed lighting state of the lamp, and the second state can be, for example, the same as the full-light lighting state of the lamp.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows a circuit configuration of a discharge lamp lighting device according to an embodiment of the present invention. The device in the same figure is different from the one in FIG.
A lamp current switching circuit 3 is added. 4 is a dimmer switch that switches the lamp between a full light state and a dimming state, and the figure shows the full light state. 5 is a lamp current setting circuit, and 6 is a buffer amplifier. Also, P W M
As the @J control circuit 2 and the subsequent stabilizing circuit, a constant power power supply device disclosed in Japanese Patent Application Laid-Open No. 63-299783 filed by the present applicant is used. In this device, a transistor is used as a semiconductor switching element, and the lamp is regulated by stabilizing the collector current of this main switching transistor and setting the operating point in a specific relationship with respect to the rated voltage and current of the lamp. It is designed to be powered by electricity. Therefore, in the current detection circuit 1, the lamp current! , rather, the collector current rc of the main switching transistor is detected. Note that this collector current ■. and lamp current IL have a relatively high correlation.

FIG. 3 is a graph showing changes in current of the main switching transistor in the device of FIG. 1, and FIG. 4 is a graph showing changes in lamp current.

Next, the operation of the apparatus shown in FIG. 1 will be explained with reference to the graphs shown in FIGS. 3 and 4.

When the power is turned on (time T0) with the dimmer switch 4 set to the full-light side as shown in the figure, the lamp current switching circuit 3 maintains the base of the transistor 31 at the ground potential by the capacitor 32. Since the transistor 33 is turned off, the transistor 33 is turned on. As a result, the transistor 51 of the lamp current setting circuit 5 is turned off, and the voltage division ratio becomes (R2+R
3)/(Rx +R2+R3), which is set on the high side.

Therefore, the loop gain of the collector current negative feedback control system is on the high side, and the collector current, and therefore the lamp current, is on the low side (dimming state). In this state, the lamp starts discharging (time TI), and the lamp and collector current IC suddenly rises, but the current detection circuit 1 starts to discharge. By detecting this, the PWM control circuit 2 controls the on/off state of a main switching transistor (not shown) in order to set the collector current Ic to the above-mentioned set current (dimming state). As a result, the lamp current 11 and the collector current ■. Immediately after reaching the peak current, the current settles down to the dimming state (time T2). The detection output (positive voltage) of the current detection circuit is voltage-divided by the lamp current setting circuit 5, and is then input to the PWM control circuit 2 via the buffer amplifier 6, as well as to the lamp current switching circuit 3. Ru. In the lamp current switching circuit 3, this positive voltage signal causes the capacitor 32 to
is charged, and the base potential of the transistor 31 rises. When the base potential of the transistor 31 exceeds the on-voltage (approximately 0.6 V) of the transistor 31, the transistor 31 is turned on and the transistor 33 is turned off. As a result, the transistor 5 of the lamp current setting circuit 5
1 is turned on, and the partial pressure ratio switches to the low side (R2)'/(R1+R2). Therefore, the gain of the negative feedback loop becomes low, and the collector current and lamp current switch to the large side (full light state) (time T3). Thereafter, the lamp continues to discharge in this state, and the tube wall temperature, tube internal pressure, lamp voltage, and brightness gradually rise from the short-circuited state, and finally enters a steady lighting state (time T4).

In the apparatus shown in Fig. 1, when a 2 kW mercury lamp was turned on as a load, the starting time was about 3 minutes, and the maximum collector current (MAX) of the main switching transistor was about 9 A. For,
The starting time when the dimming was started for the entire period was about 8 minutes.

In addition, the maximum collector current I when full-light starting is performed for the entire period
(MAX+ was about 12 A, as shown in FIG. , , = 10A, it is possible to operate within the safe operating range, whereas in the case of full-light starting, the maximum collector current I (
MAXI exceeds the maximum collector rated current 1c (maxl = i, OA) of the main switching transistor, which exceeds the safe operating area, so the maximum collector rated current IC (□.

= 20A is required.

As described above, according to this embodiment, the light is first set in the dimming state, and the lamp is shifted to the full light state upon detecting the start of discharge. The maximum current can be suppressed to a low level, and a rise time equivalent to that of full-light starting can be achieved.

Therefore, it is possible to use a main switching transistor with a low rating, and the degree of freedom in selecting the transistor to be used is increased. In addition, this embodiment uses PW
This can be realized with a small number of additional circuits to the M control IC.

[Scope of Application of the Invention] The present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications.

For example, in the above description, the lamp power is stabilized by stabilizing the collector current of the main switching transistor, but the lamp current may also be stabilized.

The present invention also applies to a discharge lamp lighting device that controls the lamp current or power by controlling the conduction angle of an AC power supply using a phase control device such as a 9-iristor as shown in Japanese Utility Model Publication No. 55-6077. Applicable.

In addition, in the above description, dimming start and full light rise are assumed, but if the rating of the semiconductor switching element permits, 1. The rise may be performed with a larger current than when completely sold. Furthermore, if it is desired to lower the rating of the semiconductor switching element, it is also possible to set the starting current to a smaller current than the dimming current. Furthermore, the present invention can be applied to devices without a dimming function by adding a lamp current switching function.

[Effects] As described above, according to the present invention, the lamp drive state is set to a state where the lamp current is lower during the transition period when the lamp shifts from the open state to the short circuit state immediately after the lamp starts lighting, so that the peak current is suppressed. be able to. Therefore, a semiconductor switching element with a smaller capacity can be used, which helps reduce the cost of the device.

Moreover, since more lamp current is allowed to flow after the lamp current (or power) is detected, the starting time can be shortened.

Furthermore, since the lighting device of the present invention detects the lamp current (or electric power) and switches the lamp current at the time of starting,
It can also be used for lamps such as HID (high intensity discharge lamps) and metal halide lamps, which do not restart until they cool down once they go out. (If a timer or the like is used to switch the lamp current, the set time will elapse before the lamp cools down, and the lamp will start lighting in a high current state, which may cause the semiconductor switching element to exceed its rating and be destroyed. )

[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 circuit diagram of a conventional discharge lamp lighting device, and FIG. 3 is a circuit diagram of a conventional discharge lamp lighting device.
1. FIG. 4 is a graph showing changes in lamp current in the device shown in FIG. 1. FIG. 4 is a graph showing changes in lamp current in the device shown in FIG. 1: Lamp current detection circuit, 2: PWM control circuit, 3: Lamp current switching circuit, 4: Dimmer switch, 5: Lamp current setting circuit,

Claims (1)

[Claims] (1) A detection circuit that detects the lamp power or lamp current of a discharge lamp, a semiconductor switching element, and an inductance element, and controls the on/off state of the switching element based on the output of the detection circuit to detect the lamp power. or a stabilizing circuit that stabilizes the lamp current; and a stabilizing circuit that stabilizes the lamp current; and switching means for switching the on/off state of the switching element to a second state in which the lamp current is larger in response to the power or current value exceeding a predetermined value. Discharge lamp lighting device.