JPH1167477A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device in which possiblity of electric shock incident occurrence due to contact with an active wire part at the time of the discharge lamps-exchanging work is suppressed low by providing a potential relation of a discharge lamp with an a.c. power source to be equal to a copper-iron type stabilizer. SOLUTION: While putting a filter circuit F between them, an inductor L1 and an a.c. power source AC are connected in series between a connection point of switching elements Q1 , Q2 and a connection point of diodes D1 , D2 . A load circuit Z is constituted of a parallel circuit of a discharge lamp La of HID (high intensity discharge) lamp and a capacitor C0 for smoothing output. One terminal y2 of the discharge lamp La and one pole of the a.c. electric power source AC are connected with a low impedance (approximately zero Ω). Consequently, the pole in the earthing side of the a.c. power source AC and the terminal y2 of the discharge lamp La are at the same potential and the risk of electric shock incident occurrence at the time of installing a discharge lamp La in a socket of an appliance can remarkably lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp lighting device, and more particularly to a discharge lamp lighting device suitable for lighting a high pressure discharge lamp such as a metal halide lamp or a high pressure sodium lamp.

[0002]

2. Description of the Related Art Conventionally, various discharge lamp lighting devices for lighting a high pressure discharge lamp (hereinafter, referred to as HID lamp: High Intensity Discharge Lamp) such as a metal halide lamp and a high pressure sodium lamp have been proposed. Such HI
In order to turn on the D lamp using a commercial AC power supply, a ballast (ballast) for limiting a discharge current is required.

FIGS. 13 and 14 show examples of a conventionally known copper-iron type ballast. The ballast shown in FIG. 13 is the so-called single choke type having the simplest configuration. Note that the capacitor C
x is inserted to correct the input power factor by passing a leading current that cancels the lagging current flowing through the choke coil Lx. On the other hand, the ballast shown in FIG. 14 uses a leakage flux transformer (leakage transformer) T, and is mainly used when the power supply voltage of the AC power supply AC is lower than the voltage of the discharge lamp La. As described above, in each ballast, one end of the discharge lamp La and one pole of the AC power supply AC are connected. However, when the discharge lamp La is turned off, the secondary voltage generated at both ends of the discharge lamp La is high (for example, 300 V).
In this case, an insulating ballast that insulates the discharge lamp La from the AC power supply AC is used.

[0004] Since the above-mentioned copper-iron type ballast creates an impedance necessary for current limiting with respect to the power supply frequency (usually 50 Hz or 60 Hz) of the AC power supply AC, a circuit element (for example, a choke coil Lx or the like) is formed. However, there are drawbacks such as an increase in size and weight. In recent years, a discharge lamp lighting device in which a ballast is formed by an electronic circuit using a semiconductor element or the like has become widespread with the progress of electronic components and circuit technology. When lighting a fluorescent lamp with such a discharge lamp lighting device, a high-frequency lighting method of applying a high-frequency voltage of several tens of kHz is generally used. However, in the case of an HID lamp, a so-called acoustic resonance phenomenon occurs when the lamp is turned on at a high frequency of several tens of kHz. Therefore, a method of lighting by applying a rectangular wave voltage of several tens to several hundreds of Hz is generally adopted.

FIG. 15 shows several tens to several hundreds of hours as described above.
1 shows an example of a discharge lamp lighting device for lighting a HID lamp 20 by applying a rectangular wave voltage of about z. A DC power supply circuit 13 for power factor correction is connected between both poles of the AC power supply AC via a noise filter circuit 12. This DC power supply circuit 13 is composed of a conventionally known boost chopper circuit including a diode bridge DB, an inductor L ₄ , a switching element Q ₅ , a diode D _{4 and a} smoothing capacitor C _4. The input current from the AC power supply AC is substantially sinusoidal. By pouring in a wave form, the input power supply power factor is increased, and the input AC voltage is converted into a boosted DC voltage and output while reducing the harmonic components of the input current.

On the output side of the DC power supply circuit 13, there is provided a lamp current limiting circuit 14 comprising a conventionally known step-down chopper circuit comprising a switching element Q ₆ , a diode D ₅ , an inductor L _{5 and a} capacitor C _5. is there.
The lamp current limiting circuit 14 functions to adjust the lamp current flowing to the HID lamp 20 from the DC output voltage of the DC power supply circuit 13 to a predetermined value, and is a part that performs the original function of the ballast.

A series circuit of a pair of switching elements Q ₁₁ , Q ₁₂ , Q ₁₃ , Q ₁₄ is connected in parallel to the output side of the lamp current limiting circuit 14, and the HID lamp 20 is connected between the connection points in both series circuits. And a starting circuit 16 are connected to the polarity reversing circuit 15. In the polarity inversion circuit 15 to turn on and off alternately each pair of pairs of switching elements _{Q 11, Q 14, Q 12} , Q 13 which is located diagonally at a low frequency of several tens to several hundreds of 100Hz by the control circuit 17 Thus, a rectangular wave voltage whose polarity is inverted at a low frequency is applied to the HID lamp 20.

The starting circuit 16 includes an oscillating circuit 16a for generating a high-frequency pulse, and a pulse transformer PT in which the oscillating circuit 16a is connected to the primary side and both ends of the HID lamp 20 are connected to the secondary side.
And applies a high-voltage pulse to start the HID lamp 20. Since the above-mentioned conventional device is a well-known technology, detailed description thereof will be omitted, but it has excellent characteristics for lighting the HID lamp 20 with a low-frequency rectangular wave.

By the way, in the above-mentioned conventional device, it is apparent that the potentials at both ends of the HID lamp 20 fluctuate with respect to one pole of the AC power supply AC. That is, the switching elements Q ₁₂ ,
One is either turned on the Q _14, or alternatively is the potential relationship between the AC power source AC and the HID lamp 20 by which of the diodes of the diode bridge DB is conducting is determined. This means that the AC power supply AC usually has a pole (ground pole) having a stable potential with respect to the ground,
This means that the potential of the lamp 20 becomes unstable with respect to the ground. In the above-mentioned copper-iron type ballast, it is possible to make the ground potential of the AC power supply AC and one end of the HID lamp 20 the same potential, but in the above-mentioned conventional device, it is impossible to do so substantially.

[0010]

On the other hand, HID lamp 2
Although there are various types of 0 shapes, a typical shape is shown in FIG.
The so-called Edison base has a single base as shown in FIG. The base part 21 is provided with an outer peripheral electrode 22 also serving as a screw part to be screwed into the socket 31 on the instrument 30 side, and an electrode at the center part. FIG. 17 shows a state where the one-sided HID lamp 20 is mounted on the socket 31 of the appliance 30. Generally, in a facility such as a store, such a device 3
0 are connected to the same power supply. Therefore, if the HID lamp 20 is turned off by any one of the appliances, if the power is turned off, the HID lamps 20 of all the other appliances 30 are turned off.
Therefore, the HID lamp 20 that has been turned off while the power is turned on without being turned off is being replaced.

Here, when the HID lamp 20 is removed from the socket 31 or mounted on the socket 31 for replacement, the outer electrode 22 of the HID lamp 20 is connected to the socket 3.
Since the HID lamp 20 is detached or mounted while being in contact with an electrode (not shown) on the first side, the outer peripheral electrode 22 in a live state is maintained until the HID lamp 20 is completely removed from the socket 31 or completely mounted. Will be exposed. As a result, there is a possibility that a part (for example, a finger) of the body of the replacement worker contacts the exposed outer peripheral electrode 22 as shown in FIG. Moreover, in the conventional apparatus shown in FIG. 15, since the potential is unstable, a voltage of about several hundred volts is generated, and there is a possibility that the replacement operator may receive an electric shock.

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a potential relationship between an AC power supply and a discharge lamp equivalent to that of a copper-iron type ballast, and to perform a discharge lamp replacement operation. It is an object of the present invention to provide a discharge lamp lighting device which is less likely to receive an electric shock even when it comes into contact with a live part.

[0013]

According to a first aspect of the present invention, there is provided an AC power supply comprising at least a switching element and an inductance element, wherein the AC power supply voltage is a low-frequency rectangular wave voltage. And a load circuit that includes a discharge lamp and has a rectangular wave voltage supplied from the power conversion circuit applied to the discharge lamp, and connects one end of the AC power supply and one end of the discharge lamp to the AC power supply. It is characterized by being connected with a low impedance to the power supply frequency and the lighting frequency of the discharge lamp. It is possible to reduce the possibility of electric shock even when contacting a live line portion.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention, one end of the AC power supply on the side connected with low impedance is set to a neutral point of the AC power supply, thereby further increasing the possibility of electric shock. Can be lower. The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the discharge lamp is a one-sided die, and one end of the discharge lamp to be connected with low impedance is an outer peripheral electrode of the one-sided die. In addition, the possibility of electric shock when the human body comes into contact with the outer peripheral electrode during the replacement work of the discharge lamp can be reduced.

[0015] The invention of claim 4 is the invention of claim 1 or 2 or 3.
In the invention, a starting circuit for applying a high voltage for starting to the discharge lamp is provided, and a high voltage from the starting circuit is applied to one end of the discharge lamp opposite to a side connected to an AC power supply with low impedance. The electric shock caused by the high voltage for starting can be prevented. According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the series circuit of the first and second switching elements and the series circuit of the third and fourth switching elements are connected to the same polarity. First and second
Are connected in parallel to both ends of a smoothing capacitor with a polarity such that no current flows when all of the first to fourth switching elements are off.
A series circuit of an AC power supply and a first inductor is connected between a connection point of the switching element and a connection point of the first and second rectifier elements, and one end of the AC power supply is connected to a connection point side of the first and second switching elements. And a series circuit of the discharge lamp and the second inductor is connected between the connection point of the first and second switching elements and the connection point of the third and fourth switching elements. And the second switching element is connected so as to be on the connection point side, and the first to fourth switching elements are each switched at a predetermined frequency.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, at least a first period during which the power supplied to the discharge lamp is mainly adjusted during the switching cycle of the first to fourth switching elements, and mainly an alternating current. Control means for controlling the switching operation of the first to fourth switching elements so as to include a second period for taking in power from a power supply, and high-speed detection means for detecting power supplied to the discharge lamp at high speed; Low-speed detection means for detecting at least one of the power supply voltage of the AC power supply and the voltage across the smoothing capacitor at a low speed, wherein the control means adjusts the first period according to the detection result of the high-speed detection means, and The second period is adjusted in accordance with the detection result of (i), the instantaneous control of the power supplied to the discharge lamp can be performed, and the discharge lamp can be stably turned on. That.

According to a seventh aspect of the present invention, in the sixth aspect, at least one of the high-speed detecting means and the low-speed detecting means performs detection based on a connection point between the first and second switching elements. Detection can be performed easily and stably, and a circuit configuration suitable for stably lighting the discharge lamp can be realized simply and inexpensively. The invention of claim 8 is characterized in that, in the invention of claim 6 or 7, the high-speed detecting means detects an instantaneous value of a current flowing through the second inductor.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, the high-speed detecting means detects a voltage between both ends of the current detecting element inserted between the connection point of the first and second switching elements and the discharge lamp. It is provided with an inverting amplifier for inverting amplification and a non-inverting amplifier for non-inverting amplification, wherein a smaller one of the amplified outputs is used as a detection value. According to a tenth aspect of the present invention, in the ninth aspect of the present invention, an inverting amplifying unit and a non-inverting amplifying unit configured by an operational amplifier operated by a single power supply with a connection point of the first and second switching elements as a ground point; High-speed detecting means comprising detecting the polarity of the lamp current flowing through the discharge lamp and increasing or decreasing the current flowing to the input side of the inverting amplifier and the non-inverting amplifier according to the detected polarity. In addition, by using a single power supply operational amplifier, the circuit configuration can be simplified and the cost can be reduced.

According to an eleventh aspect of the present invention, in the sixth aspect of the invention, the low speed detecting means is a diode connected in a forward direction between a positive electrode of the smoothing capacitor and a connection point of the first and second switching elements. A voltage dividing resistor and a capacitor are provided, and a voltage between both ends of the capacitor is used as a detection value. According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the output voltage of the power conversion circuit is inverted in synchronization with the voltage polarity of the AC power supply.

According to a thirteenth aspect of the present invention, in any one of the first to eleventh aspects, the voltage polarities of the AC power supply and the discharge lamp are always set based on one end to which the AC power supply and the discharge lamp are connected with low impedance. It is characterized by having the same polarity.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a circuit diagram showing Embodiment 1. In the present embodiment, switching elements Q ₁ , Q ₂ composed of field effect transistors having parasitic diodes D ₁₁ , D _12.
, A series circuit of switching elements Q ₃ and Q ₄ , which are also field effect transistors having parasitic diodes D ₁₃ and D _14, and a series circuit of diodes D ₁ and D ₂ are connected between both ends of the smoothing capacitor Ce. They are connected in parallel with each other. Further, Yes and the load circuit Z which includes an inductor L ₂ and the discharge lamp La between the connection point of the switching elements Q _1, Q ₂ of the connection point of the switching element Q _3, Q ₄ are connected in series, the switching element Between the connection point of Q ₁ and Q _{2 and} the connection point of the diodes D ₁ and D ₂ , an AC power supply AC is connected in series via an inductor L ₁ and a filter circuit F. Incidentally, in which the switching element Q ₁ to Q ₄ are turned on / off controlled by a control circuit (not shown).
The load circuit Z is composed of a parallel circuit of a capacitor C ₀ of the output smoothing the discharge lamp La formed of a HID lamp.

The filter circuit F is a conventionally well-known high-frequency cutoff filter composed of a capacitor Cf and an inductor Lf, as shown in FIG. 2, and includes switching elements Q _{1 to} Q _4.
Of the RF band of several hundreds kHz to several tens of MHz generated by the switching operation of the AC power supply is prevented from leaking to the AC power supply AC side, and a low-pass is applied to the power supply frequency of the AC power supply AC (normally 50 or 60 Hz). It has characteristics. Therefore, the discharge lamp La and the end y ₂ and the AC power supply AC of one pole via the one input x ₂ filter circuit F, in the region of the operating frequency of the AC power supply AC power supply frequency as well as the discharge lamp La It will be connected with very low impedance.

Next, the operation of this embodiment will be described.
First, in FIG. 1, during a period _in which the input voltage Vin of the AC power supply AC is a positive half cycle, a control circuit (not shown)
As shown in (a), switching elements Q ₂ and Q ₃ are turned on and switching elements Q ₁ and Q ₄ are turned off. At this time, smoothing capacitor Ce → switching element Q ₃ → inductor L ₂ → load circuit Z → switching element Q _A current flows through the path _{2 and} the voltage across the smoothing capacitor Ce is stepped down by the inductor L ₂ and supplied to the load circuit Z. The inductor L ₂ by a current flowing in the inductor L ₂
Is accumulated (period τ ₁ ).

Next, the switching elements Q ₁ and Q ₃ are turned on,
When the switching elements Q ₂ and Q ₄ are turned off, an input current is taken from the AC power supply AC through a path of the AC power supply AC → the inductor L ₁ → the diode D ₁ → the switching element Q ₁ , and energy is accumulated in the inductor L _1. . Further, the energy stored in the inductor L _2, the inductor L ₂ →
The load circuit Z → parasitic diode D of the switching element Q _1
11 → current flows through a path of the switching element Q _3, energy is consumed by the load circuit Z (period tau _2).

Next, all the switching elements Q ₁ to Q ₄ is a finite value the impedance of the load circuit Z is as when the discharge lamp La and the load circuit Z turned off is lit stably, the inductor L ₁ The flowing current is the inductor L ₂
The larger than that flowing through, by the stored energy of the inductor L _1, the inductor L ₁ → the diode D ₁ →
Smoothing capacitor Ce → parasitic diode D ₁₄ of switching element Q ₄ → inductor L ₂ → load circuit Z → AC power supply A
And C pathway, an inductor L ₁ → the diode D ₁ → current flows between the smoothing capacitor Ce → parasitic diode D ₁₂ → the AC power source AC path of the switching element Q _2, the inductor L ₁ stored energy and from the AC power source AC Energy is stored in the smoothing capacitor Ce and energy is also consumed in the load circuit Z.

On the other hand the impedance of the load circuit Z such as during the start of turn-on of the discharge lamp La that is included in the load circuit Z is low, becomes smaller than the current the current flowing through the inductor L ₁ flows through the inductor L _2, the switching element since a current flows through the parasitic diode D ₁₁ of Q _1, the AC power source AC
A current flows through a path of → the inductor L ₁ → the diode D ₁ → the switching element Q ₁ , and energy is stored in the inductor L ₁ . Also, the inductor L ₂ → the load circuit Z → the switching element Q by the energy stored in the inductor L _2.
A current flows through the path of the parasitic diode D _{11 of 1} → the smoothing capacitor Ce → the parasitic diode D ₁₄ of the switching element Q ₄ , and energy is consumed in the load circuit Z. When the current flowing through the inductor L ₁ to be the energy consumed by the load circuit Z is larger than the current flowing through the inductor L _2, the stored energy of the inductor L _1, the inductor L ₁ → the diode D ₁ → smoothing capacitor Ce → Parasitic diode D ₁₄ of switching element Q ₄ → Inductor L ₂ →
Load circuit Z → AC power supply AC path and inductor L ₁ →
A current flows through the diode D ₁ → the smoothing capacitor Ce → the parasitic diode D ₁₂ of the switching element Q ₂ → the path of the AC power supply AC, and the energy stored in the inductor L ₁ and the energy from the AC power supply AC are stored in the smoothing capacitor Ce. Energy is also consumed in the load circuit Z. Regardless of the magnitude of the current flowing through the inductors L ₁ and L ₂ , as long as the current flowing through the inductor L ₂ becomes zero, eventually the AC power supply AC → the inductor L ₁ → the diode D ₁ → the smoothing capacitor Ce → the switching element Q ₂ Parasitic diode D
_A current flows through the ₁₂ paths (period τ ₃ ).

Hereinafter, as shown in FIG. 3, the control circuit controls on / off of the switching elements Q _{1 to} Q ₄ to repeat periods τ _{1 to} τ ₃ at a high frequency. Voltage is supplied. On the other hand, AC power supply AC
The period input voltage V _in the negative half cycle from Fig 3
As shown in (b), when the switching elements Q ₁ and Q ₄ are on and the switching elements Q ₂ and Q ₃ are off, the smoothing capacitor Ce → the switching element Q ₁ → the load circuit Z → the inductor L ₂ → the switching element Q ₄ voltage of the smoothing capacitor Ce current flows in the path is supplied to the step-down to the load circuit Z by the inductor L _2. Moreover, the energy in the inductor L ₂ is accumulated by the current flowing in the inductor L _2.

Next, the switching elements Q ₂ and Q ₄ are turned on,
When the switching elements Q ₁ and Q ₃ are turned off, a current flows through the path of the AC power supply AC → the switching element Q ₂ → the diode D ₂ → the inductor L ₁ , and energy is accumulated in the inductor L ₁ . Further, the energy stored in the inductor L _2, is the energy consumed by the inductor L ₂ → switching element Q ₄ → switching element parasitic diode of Q ₂ D ₁₂ → load circuit path load current flows in the Z circuit Z.

Next, when all of the switching elements Q _{1 to} Q ₄ are turned off, the impedance of the load circuit Z becomes a finite value as when the high pressure discharge lamp included in the load circuit Z is stably lit. current flowing through the inductor L ₁ is the greater than the current flowing in the inductor L ₂ Te, inductor L ₁ of the stored energy by the inductor L ₁ → the AC power source AC → load circuit Z → inductor L ₂ → parasitic diode of the switching element Q ₃ D ₁₃ → smoothing capacitor Ce
→ a path of the diode D _2, the inductor L ₁ → the AC power source AC → current flows in the parasitic diode D ₁₁ → smoothing capacitor Ce → diode D ₂ of the path of the switching element Q _1, the energy stored in the inductor L ₁ and the AC power source Energy from AC is stored in the smoothing capacitor Ce, and energy is also consumed in the load circuit Z.

On the other hand, the impedance of the load circuit Z such as during the start of turn-on of the discharge lamp La that is included in the load circuit Z is low, becomes smaller than the current the current flowing through the inductor L ₁ flows through the inductor L _2, switch Element Q ₂
Parasitic diode since current flows through the D _12, an AC power source A of
A current flows through the path of C → switching element Q ₂ → diode D ₂ → inductor L ₁ , and energy is stored in inductor L ₁ . Also, the inductor L ₂ → the parasitic diode D ₁₃ of the switching element Q ₃ → the smoothing capacitor Ce → the switching element Q by the energy stored in the inductor L _2.
The current flows in the path of the parasitic diode D ₁₂ → load circuit Z of ₂ and the load circuit Z consumes energy. When the current flowing through the inductor L ₁ to be the energy consumed by the load circuit Z is larger than the current flowing through the inductor L _2, the inductor L by the stored energy of the inductor L _1
1 → AC power supply AC → Load circuit Z → Inductor L ₂ → Parasitic diode D ₁₃ of switching element Q ₃ → Smoothing capacitor Ce → Diode D ₂ path and inductor L ₁ → AC power supply AC → Parasitic diode of switching element Q ₁ D
₁₁ → current flows between the smoothing capacitor Ce → diode D ₂ of the path, the energy from the stored energy and an AC power source AC inductor L ₁ is the energy consumed even load circuit Z with is stored in the smoothing capacitor Ce. Regardless of the magnitude of the current flowing through the inductors L ₁ and L ₂ , as long as the current flowing through the inductor L ₂ becomes zero, eventually the AC power supply AC → the parasitic diode D ₁₁ of the switching element Q ₁ →
Smoothing capacitor Ce → diode D ₂ → inductor L ₁
The current will flow through the path.

[0031] Hereinafter, similarly to the period input voltage V _in the positive half cycle of the AC power source AC, the control circuit is above operation is repeated by turning on / off control of the switching elements Q ₁ to Q _4, load The circuit Z is supplied with a unidirectional DC voltage. Accordingly, as shown in FIG. 4, a rectangular wave lamp voltage V _La whose polarity is inverted in synchronization with each half cycle of the AC power supply AC is supplied to the discharge lamp La via the capacitor C ₀ to the load circuit Z by the above operation. Is done.

As described above, in the present embodiment, the discharge lamp La
End for the one pole of y ₂ and the AC power source AC is connected with a low impedance (substantially zero Omega), comparable to the potential relationship between the AC power source AC in the prior art copper iron ballast with a discharge lamp La of obtaining a relationship, i.e. the one end y ₂ of the AC power source AC ground side electrode and the discharge lamp La becomes possible to have the same potential. As a result, the risk of electric shock when the discharge lamp La is mounted on the socket of the appliance as described in the conventional example can be greatly reduced.

(Embodiment 2) FIG. 5 is a circuit diagram of this embodiment. In Embodiment 1, a neutral element Ln in a single-phase three-wire commercial AC power supply AC 'is connected to a switching element Q.
_1, connected to the connection point Q ₂ 'are connected at one end and a low impedance of the discharge lamp La. According to the above configuration, since one end of the discharge lamp La is always grounded via the neutral wire Ln, the risk of electric shock can be further reduced as compared with the first embodiment, and the discharge lamp La is safer. Since the potential of the entire circuit is stabilized, effects such as stabilization of circuit operation and reduction of radiation noise can be obtained.

Also in the case of a three-phase four-wire commercial AC power supply AC "as shown in FIG. 6, the neutral point N is connected to one end of the discharge lamp La via the connection point of the switching elements Q ₁ and Q _2. (Embodiment 3) Fig. 7 shows a circuit diagram of the present embodiment, and shows a circuit diagram of a single-die HID lamp 20 described in the conventional example. The outer peripheral electrode 22 side of the discharge lamp La
_1, via the connection point Q ₂ 'is connected to an AC power source AC grounding electrode.

Thus, according to the present embodiment, the outer peripheral electrode 22 of the discharge lamp La is always kept at the same potential as the ground potential, so that when the discharge lamp La is replaced, the outer body 22 is Therefore, a very safe discharge lamp lighting device can be obtained in which a human body can be generally regarded as being grounded to the ground, so that a potential difference is not generated between the outer peripheral electrode 22 and electric shock. .

(Embodiment 4) In the conventional example shown in FIG. 15, the secondary winding of the pulse transformer PT of the starting circuit 16 is divided so that high voltage pulses are applied to both ends of the discharge lamp La. Thus, the voltage applied to each winding is only half the starting voltage of the discharge lamp La.

However, when the starting circuit 16 is used in the configuration of the third embodiment, a high-voltage pulse for starting is also applied to the outer peripheral electrode 22 of the discharge lamp La which may come into contact with the human body. There is a risk of electric shock due to the high voltage pulse. In this embodiment, by inserting the starting circuit 1 composed of an oscillation circuit 2 and the pulse transformer PT between the one ends of the capacitor C ₀ of the discharge lamp La as shown in FIG. 8,
One end y ₁ side of the non-AC power supply AC side of the discharge lamp La only so as to apply a starting high voltage pulse from the starting circuit 1.

According to this embodiment, the possibility of electric shock due to the high-voltage pulse for starting can be reduced. In particular, similarly to the third embodiment, the outer peripheral electrode 22 of the discharge lamp La is connected to the AC power source AC. Is connected, the possibility of electric shock due to the high voltage pulse is eliminated, and a very safe discharge lamp lighting device can be provided. (Embodiment 5) FIG. 9 is a circuit diagram showing the present embodiment,
Since the basic configuration is the same as that of the first embodiment, the same parts are denoted by the same reference numerals and the description thereof will be omitted, and only the features that are the features of the present embodiment will be described.

As described in the first embodiment, the AC power supply AC
There are three periods τ ₁ to τ ₃ in the control operation of the switching elements Q _{1 to} Q _{4 in} each half cycle of which the period τ ₁ is transmitted from the smoothing capacitor Ce to the discharge lamp La via the inductor L _2. During the period when current flows, the period τ ₂ is the AC power supply AC
The period for taking in current from is determined. That is, it can be said that the period τ ₁ is a period for mainly restricting power supply to the discharge lamp La, and the period τ ₂ is a period for mainly restricting power supply from the AC power supply AC.

In this embodiment, a low-resistance detection resistor Rd is inserted between one end y ₂ of the discharge lamp La and a connection point between the switching elements Q ₁ and Q ₂ , and a load circuit is formed based on the voltage generated at the detection resistor Rd. a fast detector 3 that detects an instantaneous value of the current flowing through the Z and the inductor L ₂ at high speed, a low speed detector 4 for detecting the voltage across the smoothing capacitor Ce at a low speed,
The period τ is determined based on the detection value Vd ₁ from the high-speed detector 3.
_{A first} period determining unit 5 for determining 1 and a _second period τ ₂ for determining the period τ ₂ based on the detection value Vd ₂ from the low-speed detector 4.
, A polarity detector 7 for detecting the polarity of the AC power supply AC, a reference oscillator 8 for generating a reference signal for determining the switching cycle T of the switching elements Q _{1 to} Q ₄ , Switching elements Q _{1 to} Q ₄ according to the signals from the second period determination units 5 and 6 and the detection signal from the polarity detector 7, the reference signal supplied from the reference oscillator 8, and the polarity signal supplied from the polarity detector 7. And a main control unit 9 for controlling the on / off of the lamp, and variably adjusts the periods τ ₁ and τ ₂ to perform instantaneous control of the lamp power supplied to the discharge lamp La.

That is, if the amount of current flowing through the discharge lamp La increases and the detection value Vd ₁ from the high-speed detector 3 increases,
The first period determination unit 5 gives a command to the main control unit 9 to shorten the period τ ₁ , and conversely, the amount of current flowing through the discharge lamp La decreases, and the detection value Vd ₁ from the high-speed detector 3 is reduced. Is reduced, the first period determining unit 5 gives a command to the main control unit 9 to extend the period τ ₁ . Further, when the AC power supply AC fluctuates, the voltage Vce across the smoothing capacitor Ce also fluctuates. However, the voltage Vce is detected by the low-speed detector 4 and the second period determining unit 6 responds to the increase or decrease. Stabilizing the voltage Vce across the smoothing capacitor Ce without being affected by the instantaneous value of the power supply voltage of the AC power supply AC by giving a command to shorten or lengthen the period τ ₂ to the main control unit 9. Can be.

In the high-speed detector 3, as shown in FIG. 10, the voltage V _Rd across the detection resistor Rd is applied to the operational amplifier O.
And input to P _1, the inverting amplifier 3a comprised of OP ₂ and the non-inverting amplifier 3b, so that the taking out an output Vd ₁ of not smaller in both output. If such a high-speed detector 3 is used, the switching elements Q ₁ , Q
The current flowing through the discharge lamp La or the inductor L ₂ of the _second connection point as a ground point SG signal system can be detected and stable at high speed. Incidentally, since the detection resistor Rd is low resistance, the state where one end y ₂ when similarly substantially alternating-current power supply AC filter circuit F of Embodiment 1 and the one end of the discharge lamp La is connected with low impedance Can be maintained.

On the other hand, in the low-speed detector 4, as shown in FIG.
The positive electrode side through the diode D ₃ of the voltage dividing resistors R _3, R ₄
And connecting the integrator circuit from the capacitor C _3, and outputs a voltage Vd ₂ obtained by integrating the instantaneous values of the voltage across the smoothing capacitor Ce. Here, the switching element Q
₂ to be turned on / off at all times a high speed in all cycles of the AC power source AC, so that the switching element Q ₂ is grounded point SG in when ON signal system is equivalently connected to the negative electrode side of the smoothing capacitor Ce. Therefore, the detection voltage Vd ₂ proportional to the voltage Vce across the smoothing capacitor Ce determined by the voltage dividing ratio of the voltage dividing resistors R ₃ and R ₄ of the low-speed detector 4 becomes the capacitor C ₃
Obtained at both ends. The time constant of the integrating circuit, it is necessary to set to a value greater than the switching frequency of the switching element Q ₂ (1 / T) for high frequency ripple reduction of the detection voltage Vd _2, the detection voltage Vd ₂ Detection Will be performed at a low speed.

As described above, in the present embodiment, the reference points for detection by the high-speed detector 3 and the low-speed detector 4 are set to the switching elements Q ₁ and Q _{2 to} which the AC power supply AC and the discharge lamp La are connected with low impedance. , The current and voltage required for the operation control of the circuit can be detected easily and stably.
By performing the instantaneous control of the lamp power based on the detected values Vd ₁ and Vd ₂ that are stably detected, the discharge lamp La can be stably turned on.

[0045] In the high-speed detector 3 in (Embodiment 6) Embodiment 5, the polarity of the current I _L2 voltage across V _Rd of the detection resistor Rd is flowing to the inductor L ₂ (or polarity of the lamp voltage of the discharge lamp La) Accordingly, since the ground point SG of the signal system is shifted to the positive and negative sides as a zero point, the operational amplifiers OP ₁ and OP ₂ used for the inverting amplifier 3a and the non-inverting amplifier 3b require two types of positive and negative power supplies Vcc and Vee. It is a cause of up.

Therefore, in the present embodiment, a high-speed detector 3 'which can achieve cost reduction by using a single power supply operational amplifier is used.
Is exemplified. FIG. 12 is a circuit diagram of a main part including the high-speed detector 3 'in the present embodiment. The operational amplifier OP ₃ to an inverting amplifier 3a 'as well as non-inverting amplifier 3b' that operates from a single power supply Vcc, OP ₄ is used, the operational amplifier OP _3,
The current flowing through the input resistor on the side of the voltage V _Rd of OP ₄ are input are as varied in accordance with the transistor Qa _1, Qa ₂ on / off. Where transistor Q
On / off of a ₁ and Qa ₂ is performed by the output Vb of the load voltage polarity detector 10 which detects the polarity of the current I _L2 flowing through the inductor L ₂ (or the polarity of the lamp voltage of the discharge lamp La).

[0047] The PNP through a resistor to the inverting input of the inverting amplifier 3a 'in the operational amplifier OP ₃ transistor Qa ₁
The collector is connected. This transistor Qa ₁
Are connected to the power supply Vcc, and the output Vb from the load voltage polarity detector 10 is input to the base. While the non-inverting input of the NPN transistor Qa ₂ toward the collector of non-inverting amplifier 3b 'in the operational amplifier OP ₄ are connected. The emitter of the transistor Qa ₂ is connected to ground, the output Vb of the load voltage polarity detector 10 is input to the base.

Next, the operation of the high-speed detector 3 'in this embodiment will be described. First, the signal system ground point SG
Current I _L2 in the inductor L ₂ is to flow in the direction of the arrow, the voltage across V _Rd also positive detection resistor Rd when the lamp voltage of the discharge lamp La is positive as a zero point. At this time, the output Vb of the load voltage polarity detector 10 becomes L level, the transistor Qa ₁ is turned on, the transistor Qa ₂ is turned off. 'The output of forcibly dropped to zero, a non-inverting amplifier 3b' Therefore, since the inverting input terminal of the operational amplifier OP ₃ current flows through the transistor Qa ₁ from the power supply Vcc inverting amplifier 3a is performing normal operation Voltage V
And it outputs a voltage Vd ₁ was a non-inverting amplifying _Rd.

On the other hand, when the lamp voltage of the discharge lamp La is negative, the current I _L2 flows in the direction opposite to the direction indicated by the arrow, so that the voltage V _Rd across the detection resistor Rd becomes negative. At this time, the output Vb of the load voltage polarity detector 10 becomes H level, the transistor Qa ₁ is turned off, the transistor Qa ₂ is turned on. 'The output of is zero, inverting amplifier 3a' Therefore a non-inverting input terminal of the operational amplifier OP ₄ is dropped to the ground non-inverting amplifier 3b is a voltage Vd ₁ which inverts and amplifies the voltage V _Rd performing normal operation Is output.

As described above, in this embodiment, the operational amplifier O
The inverting input terminal voltage can always be higher than the non-inverting input terminal voltage in the relationship between the common mode voltages of P ₃ and OP ₄ , or within the range of the common mode voltage allowed for the single power supply operational amplifiers OP ₃ and OP _4. Can be set. Since the high-speed detector 3 can be configured using the operational amplifiers OP ₃ and OP ₄ of the single power supply Vcc, the cost can be reduced without requiring two types of power supplies, positive and negative.

[0051]

According to a first aspect of the present invention, there is provided a power conversion circuit configured to include an AC power supply, at least a switching element and an inductance element, configured to convert the AC power supply voltage into a low-frequency rectangular wave voltage, and a discharge lamp. And a load circuit for applying a rectangular wave voltage supplied from the power conversion circuit to the discharge lamp. The one end of the AC power supply and the one end of the discharge lamp have a low frequency with respect to the power supply frequency of the AC power supply and the lighting frequency of the discharge lamp. Because it is connected by impedance, it obtains the same potential relationship between the AC power supply and the discharge lamp as the copper-iron type ballast, and reduces the possibility of electric shock even if it comes into contact with live parts when replacing the discharge lamp. There is an effect that can be.

According to the second aspect of the present invention, since one end of the AC power supply on the side connected with low impedance is set as the neutral point of the AC power supply, there is an effect that the possibility of electric shock can be further reduced. According to the third aspect of the present invention, the discharge lamp is a one-sided die, and one end of the discharge lamp on the side connected with low impedance is an outer peripheral electrode of the one-sided die. There is an effect that the possibility of electric shock in the case of contact can be reduced.

According to a fourth aspect of the present invention, there is provided a starting circuit for applying a high starting voltage to the discharge lamp. The starting circuit is connected to one end of the discharge lamp on the side opposite to the side connected to the AC power supply with low impedance. Is applied, so that an electric shock due to the starting high voltage can be prevented. According to a sixth aspect of the present invention, at least a first period of adjusting power supply to a discharge lamp at least during a switching cycle of the first to fourth switching elements and a second period for mainly taking in power from an AC power supply. Control means for controlling the switching operation of the first to fourth switching elements so as to include a period, high-speed detection means for detecting power supplied to the discharge lamp at high speed, and a power supply voltage of an AC power supply and a smoothing capacitor. Low-speed detection means for detecting at least one of the both-end voltages at a low speed;
And the second period is adjusted according to the detection result of the low-speed detecting means, so that instantaneous control of the power supplied to the discharge lamp can be performed, and the discharge lamp can be stably turned on. There is an effect that can be.

According to the seventh aspect of the present invention, at least one of the high-speed detection means and the low-speed detection means performs the detection based on the connection point of the first and second switching elements, so that the detection can be performed easily and stably. Thus, there is an effect that a circuit configuration suitable for stably lighting the discharge lamp can be realized simply and inexpensively. According to a tenth aspect of the present invention, there is provided an inverting amplifying unit and a non-inverting amplifying unit configured by an operational amplifier operated by a single power supply with a connection point of the first and second switching elements being a ground point, A means for detecting the polarity and a means for increasing or decreasing the current flowing to the input side of the inverting amplifier and the non-inverting amplifier in accordance with the detected polarity constitutes a high-speed detecting means. There is an effect that the configuration can be simplified and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a circuit diagram of a filter circuit of the above.

FIGS. 3A and 3B are time charts for explaining on / off operations of the switching elements Q _{1 to} Q _{4 in} the above.

FIG. 4 (a) is an AC power supply voltage waveform diagram in the same as above.
(B) is a lamp voltage waveform diagram.

FIG. 5 is a circuit diagram showing a second embodiment.

FIG. 6 is a circuit diagram showing another example of the AC power supply in Embodiment 1;

FIG. 7 is a circuit diagram showing a third embodiment.

FIG. 8 is a circuit diagram showing a fourth embodiment.

FIG. 9 is a circuit diagram showing a fifth embodiment.

FIG. 10 is a circuit diagram of the high-speed detector in the above.

FIG. 11 is a partially omitted circuit diagram of the above.

FIG. 12 is a circuit diagram of a high-speed detector according to a sixth embodiment.

FIG. 13 is a circuit diagram showing a conventional copper-iron type ballast.

FIG. 14 is a circuit diagram showing another example of the conventional copper-iron type ballast.

FIG. 15 is a circuit diagram showing a conventional example.

FIG. 16 is an external view showing a single-die HID lamp.

FIG. 17 is a side cross-sectional view of an appliance using a single-die HID lamp.

FIG. 18 is a side cross-sectional view of an appliance using a single-die HID lamp.

[Explanation of symbols]

Q _{1 to} Q ₄ Switching element AC AC power supply Ce Smoothing capacitor La Discharge lamp L ₁ , L ₂ inductor D ₁ , D ₂ diode

Claims (13)

[Claims] An AC power supply, and a power conversion circuit configured to include at least a switching element and an inductance element and convert an AC power supply voltage into a low-frequency rectangular wave voltage;
A discharge circuit comprising a discharge lamp and a load circuit for applying a rectangular wave voltage supplied from the power conversion circuit to the discharge lamp, and connecting one end of the AC power supply and one end of the discharge lamp to a power supply frequency of the AC power supply and a lighting frequency of the discharge lamp. A discharge lamp lighting device characterized by being connected to the discharge lamp with low impedance. 2. The discharge lamp lighting device according to claim 1, wherein one end of the AC power supply connected at a low impedance is set as a neutral point of the AC power supply. 3. The discharge lamp lighting according to claim 1, wherein the discharge lamp is a one-sided die, and one end of the discharge lamp on the side connected with low impedance is an outer peripheral electrode of the one-sided die. apparatus. 4. A starting circuit for applying a high voltage for starting to a discharge lamp, wherein a high voltage from the starting circuit is applied to one end of the discharge lamp opposite to a side connected to an AC power supply with low impedance. The discharge lamp lighting device according to claim 1, 2 or 3, wherein: 5. A series circuit of first and second switching elements, a series circuit of third and fourth switching elements, and a series circuit of first and second rectifying elements connected to the same polarity. When the first to fourth switching elements are all off, they are connected in parallel to both ends of the smoothing capacitor with a polarity such that no current flows, and the connection point of the first and second switching elements is connected to the first and second switching elements. A series circuit of an AC power supply and a first inductor is connected between the connection points of the rectifier elements such that one end of the AC power supply is on the connection point side of the first and second switching elements, and the first and second switching elements are connected. A series circuit of a discharge lamp and a second inductor is connected between the connection point of the element and the connection point of the third and fourth switching elements such that one end of the discharge lamp is on the connection point side of the first and second switching elements. Connect to the first The discharge lamp lighting device according to any one of claims 1 to 4, wherein each of the first to fourth switching elements is operated to perform a switching operation at a predetermined frequency. 6. A first period for adjusting power supplied to a discharge lamp at least mainly during a switching cycle of the first to fourth switching elements and a second period for mainly taking power from an AC power supply. Control means for controlling the switching operation of the first to fourth switching elements so as to be included; high-speed detection means for detecting power supplied to the discharge lamp at high speed; power supply voltage of the AC power supply and voltage across the smoothing capacitor Low-speed detection means for detecting at least one of the low-speed detection means at a low speed, and
6. The discharge lamp lighting device according to claim 5, wherein the period is adjusted and the second period is adjusted according to the detection result of the low-speed detecting means. 7. The discharge lamp lighting device according to claim 6, wherein at least one of the high-speed detection means and the low-speed detection means performs detection based on a connection point of the first and second switching elements. 8. The discharge lamp lighting device according to claim 6, wherein the high-speed detecting means detects an instantaneous value of a current flowing through the second inductor. 9. An inverting amplifier for inverting and amplifying a voltage between both ends of a current detecting element inserted between a connection point of the first and second switching elements and a discharge lamp, and a non-inverting amplifier for non-inverting amplifying. 9. The discharge lamp lighting device according to claim 8, further comprising an inverting amplifier, wherein an output of a smaller one of the amplified outputs is used as a detection value. 10. An inverting amplifying unit and a non-inverting amplifying unit comprising an operational amplifier operated by a single power supply with a connection point of the first and second switching elements as a ground point, and a polarity of a lamp current flowing through the discharge lamp. 10. The discharge lamp lighting according to claim 9, wherein the high-speed detection means comprises means for detecting and increasing / decreasing the current flowing to the input side of the inverting amplifier and the non-inverting amplifier in accordance with the detected polarity. apparatus. 11. The low-speed detecting means includes a diode, a voltage dividing resistor, and a capacitor connected in a forward direction between a positive electrode of the smoothing capacitor and a connection point of the first and second switching elements. 7. The discharge lamp lighting device according to claim 6, wherein the voltage between both ends is used as a detection value. 12. The discharge lamp lighting device according to claim 1, wherein the polarity of the output voltage of the power conversion circuit is inverted in synchronization with the voltage polarity of the AC power supply. 13. The discharge lamp according to claim 1, wherein the AC power supply and the discharge lamp have the same polarity with respect to one end connected to the discharge lamp with low impedance. 2. The discharge lamp lighting device according to claim 1.