JP2000357594A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make starting voltage of a discharge lamp lighting device asymmetric, reduce starting voltage as viewed as a peak-to-peak voltage value while starting performance is kept, and make voltage resistance of a component low and the miniaturization by setting the starting voltage being applied to an electrode on the low resistivity side and the starting voltage being applied to an electrode on the high resistivity side in a specific relation. SOLUTION: Starting voltage being applied to an electrode on the low resistivity side is set in V1 to earthed voltage, starting voltage being applied to an electrode on the high resistivity side is set V2 to the earthed voltage, and starting voltage is applied so as to have the relation of |V1|>|V2|. Preferably, at the starting of a lamp, a DC component is superimposed on AC lamp voltage, height of the starting voltage is alternately varied to the ground surface, the starting voltage is corrected according to the using time of the lamp, the frequency at the start of the lamp is made higher than that in the stable lighting of the lamp, and the shapes of bases at opposite ends of the lamp are made asymmetric.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for starting and lighting a fluorescent lamp provided with a conductive film with an AC voltage.

[0002]

2. Description of the Related Art Generally, a discharge lamp lighting device has no lamp load,
In the event of an error such as incorrect insertion of a lamp, disconnection of a lamp filament, or end of lamp life, consideration has been given to restricting or stopping the output to a load for safety. In particular, electronic ballasts composed of electronic components often implement protection measures such as an oscillation stop function and an intermittent oscillation function for the above-mentioned abnormalities.

FIG. 20 shows a conventional example (Japanese Patent Application Laid-Open No. 9-153797).
FIG. The circuit includes a rectifier DB for full-wave rectification of an AC power supply, a capacitor C2 connected to an output terminal of the rectifier DB, and a series connection of switching elements Q1 and Q2 connected to both ends of the capacitor C2. A series connection of diodes D1 and D2 connected to both ends, and a switching element Q1 via a diode D2.
L1 and smoothing capacitor C connected to both ends of the
1 and a series connection of a capacitor C3 connected to both ends of the switching element Q2, an inductor L2, and a primary winding of a transformer T1, and two switching elements Q1 and Q2 are alternately turned on and off. Is repeated, thereby supplying AC high frequency power to the discharge lamp 2 as a load via the secondary winding of the transformer T1 and the DC component cutting capacitor C4. Also, an inductor L1, a smoothing capacitor C1, a diode D1,
In the circuit composed of D2, when the switching element Q2 is turned on, the AC power supply → rectifier DB → inductor L1 → smoothing capacitor C1 → diode D2 → switching element Q2 →
By supplying a current through a path from the rectifier DB to the AC power supply, a charging voltage of a predetermined value is generated in the smoothing capacitor C1. When the output voltage of the rectifier DB falls below the charging voltage of the smoothing capacitor C1, the charging voltage of the smoothing capacitor C1 is reduced. Serve as a power supply for an inverter circuit including the switching elements Q1 and Q2. That is, the circuit including the inductor L1, the smoothing capacitor C1, and the diodes D1 and D2 operates as a so-called partial smoothing power supply.

A resistor R1 connected in parallel between the non-power supply terminals of the discharge lamp 2 and filaments f1, f
The resistors R2 and R3, which are connected in parallel to both ends of the switching elements Q1 and Q2 via the resistors R2 and R3, and the resistors R1 to R3 and the voltage determined by the filaments f1 and f2 of the discharge lamp 2 compare with the reference voltage Vref and oscillate. A circuit IC2 for outputting a signal is provided in the circuit IC2 to detect no load and to detect a filament break.

The operation of this detection circuit is as follows.
When a normal discharge lamp is installed, the filament f1 of the discharge lamp → the resistance R1 → the filament f2 of the discharge lamp → the resistance R
Since a current flows through the path of 2 → resistance R3, the resistances R1 to R
3. The voltage of the resistor R3 determined by the filaments f1 and f2 of the discharge lamp rises, and in this state, the reference voltage Vre
By setting so as to exceed f, the IC1 outputs a low-level signal to the oscillation circuit IC2. Oscillator circuit IC
2 receives this signal and continues the oscillating operation of switching elements Q1 and Q2. On the other hand, if the discharge lamp is not mounted or at least one of the filaments f1 and f2 of the discharge lamp is broken, the current path to the resistors R2 and R3 as described above is cut off, and the voltage of the resistor R3 drops to substantially zero. That is, when the voltage falls below the predetermined voltage Vref, the IC1 outputs a high-level signal to the oscillation circuit IC2. The oscillating circuit IC2 receives this signal and switches the switching element Q for protecting circuit components.
1 and Q2 are stopped, and the switching elements Q1 and Q2 are stopped.
The oscillation of Q2 is stopped. Here, assuming that the DC component cutting capacitor C4 is charged, there is a current path of power supply → DC component cutting capacitor C4 → secondary winding of transformer T1 → resistance R2 → resistance R3 → power supply. do not do.

As described above, in this conventional example, as a means for detecting an abnormal state such as no-load of the lamp and disconnection of the filament, a DC voltage divided through a filament resistor and a resistor connected in parallel to the lamp is used. It is determined whether the component is equal to or higher than the reference voltage. Since this no-load detection method is performed via both filaments of the lamp, it is very effective in detecting that the filament is disconnected and the DC current path is interrupted, and is generally used.

FIG. 21 shows voltage waveforms across the lamp when the lamp is preheated, started, and turned on by the conventional circuit. As is clear from FIG. 21, the voltage at both ends of the lamp in this circuit is characterized in that the voltage from the ground plane is asymmetrical between positive and negative. During preheating, starting, and lighting, a DC component for no-load detection is always superimposed on the oscillation voltage of the inverter. Therefore, the positive lamp voltage of the DC voltage with respect to the ground plane is V0−p +, and the negative lamp voltage is Is V0-p-,
Inevitably, the relationship | V0−p + |> | V0−p− | is established. In this way, when the starting voltage of the lamp is asymmetric with respect to the ground at the midpoint, it is necessary to set a high starting voltage as seen from the voltage Vpp from the (positive) peak to the (negative) peak.

On the other hand, recent lamps tend to have a higher starting voltage for higher efficiency. In other words, in order to operate a modern high-efficiency fluorescent lamp without problems, the ballast must apply a sufficiently low voltage to the lamp during preheating and apply a very high voltage to the lamp during startup. Generally, when the starting voltage is high, that is, when the oscillation voltage of the ballast is high, the voltage applied at the time of preheating tends to increase. Therefore, this condition narrows the allowable design range of the ballast, resulting in a problem that the cost is increased.

The reason will be described below. First,
The electrode of the fluorescent lamp will be described. This electrode is formed by attaching a substance called an emitter to a thin tungsten wire having a double coil shape (or a triple coil shape). This substance is to make electron emission easier,
Barium oxide (low work function) and the like are currently used. The method of making is to drip a barium carbonate slurry into the above-mentioned coiled tungsten wire, dry it, and heat it during the lamp evacuation step to form barium oxide (BaCO ₃ → BaO + CO ₂ : C
O ₂ is removed out of the lamp during the evacuation process). As can be understood from this step, the state of adhesion of the emitter material attached to the electrode to the tungsten wire is not so strong.

Next, the electron emission mechanism of this electrode will be described. The current emitted from the electrode is expressed by the following equation. I = α * T ² * exp (−β / T) * exp (√E /
T) α: Constant related to the electrode material β: Constant related to the electrode material T: Electrode temperature E: Electric field strength of the cathode falling part (related to the cathode drop voltage)

As can be seen from this equation, the discharge current is determined by the electrode temperature and the cathode drop voltage. If the electrode temperature is low, that is, if the preheating is insufficient at startup, the cathode drop voltage will increase to supply the current. As the cathodic drop voltage increases, the kinetic energy of the ions (supplied by the cathodic drop voltage) as they collide with the electrode increases. For this reason, the influence of ion bombardment on the electrodes cannot be ignored.

As described above, the method of attaching the emitter to the electrode is not so robust. Therefore, when the cathode drop voltage rises, the emitter is separated from the tungsten wire by the impact of the ions. This causes blackening of the electrode portion of the lamp, and reduces the number of emitters attached to the tungsten wire, resulting in a short life. In order to prevent this, it is necessary to warm the electrodes sufficiently before starting.

[0013]

FIG. 17 shows the resistance distribution of a lamp having a conductive film of each lamp maker. In the lamps manufactured by A and B, the resistance distribution of the conductive film is largely asymmetric when viewed from the center of the lamp in the longitudinal direction, and the resistance at the tube end on the maker mark side of the lamp surface is low. The resistance value at the tube end of the opposite lamp is very high. In the lamps manufactured by Company C and Company D, the resistance distribution of the conductive film is slightly asymmetrical when viewed from the center of the lamp in the longitudinal direction, and the resistance at both ends of the lamp is high and the center is low. I have. Such a difference is caused by a difference in the manufacturing process for each company. Although there is a difference between the lamps with the conductive film and the respective manufacturers, it can be said that the resistance distribution is asymmetric when viewed from the center in the longitudinal direction. In such a lamp, the starting voltage is asymmetrical between positive and negative.

However, in the conventional copper-iron ballast, there is no means for controlling whether the starting voltage is to be started in either positive or negative polarity with respect to a lamp whose starting voltage is asymmetrical, and the lamp is a commercial frequency sine wave. Therefore, | V0−p + | = | V
It was necessary to apply a voltage having a large amplitude in both the positive and negative directions, 0-p- | = | lamp starting voltage |, to the lamp.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to maintain the starting performance of a lamp having an asymmetric starting voltage by making the starting voltage of a discharge lamp lighting device asymmetric. While reducing the starting voltage as seen from peak to peak value.

[0016]

According to the present invention, in order to solve the above-mentioned problems, the tube wall has a resistance along the direction of the discharge path, and the resistance distribution is asymmetric when viewed from the center in the longitudinal direction of the lamp. In a discharge lamp lighting device for lighting a simple lamp with an AC voltage, the starting voltage applied to the electrode having the lower resistivity is V1 with respect to the ground potential, and the starting voltage applied to the electrode having the higher resistivity is V1. When V2 is set to the ground potential, the starting voltage is applied so that | V1 |> | V2 |.

[0017]

(Embodiment 1) A first embodiment of the present invention will be described. The feature of the first embodiment is that the higher starting voltage V0-p of the positive / negative asymmetric starting voltage is applied to the electrode with the lower resistance component of the lamp with the conductive film having the asymmetrical resistance distribution in the discharge path direction. By applying the voltage, the starting voltage Vpp of the peak-to-peak value applied to both ends of the lamp is reduced.

FIG. 1 is an explanatory view of Embodiment 1 of the present invention.
It is a microscopic view of a lamp voltage when a DC voltage _{VDC of} 50 V is applied while being superimposed on a high-frequency AC voltage with respect to a ground plane. Assuming that the positive lamp voltage of the DC voltage _VDC is V0−p + and the negative lamp voltage is V0−p−,
| V0-p + |> | V0-p- |. Ambient temperature is normal temperature. Under the condition of the lamp FLR40S36 with a conductive film, when the side having a small resistance per unit length near one electrode is connected to the positive side, the lamp voltage on the positive side is | V0- p + | = 500 V, negative lamp voltage is | V
The lamp was turned on at 0-p- | = 400V. Therefore, the voltage difference from the positive peak to the negative peak is Vpp
= | V0-p + | + | V0-p- | = 900V.

FIG. 2 is an explanatory view of a comparative example with respect to the present invention, and microscopically shows a high-frequency lamp voltage line-symmetric with respect to a ground plane. V0-
Assuming that p + and the negative lamp voltage are V0−p−, | V0
−p + | = | V0−p− | Ambient temperature is normal temperature, and under the condition of the lamp FLR40S36 with a conductive film, the lamp voltage on the positive side can be connected to either the positive side or the negative side with the smaller resistance per unit length near one electrode. Is | V0-p + | = 500V, and the lamp voltage is | V0-p- | = 500V on the negative side, and the lamp is turned on. Therefore, the voltage difference from the positive peak to the negative peak is V
pp = | V0-p + | + | V0-p- | = 1000 V

As described above, the embodiment of FIG. 1 in which the present invention is implemented is different from the comparative example of FIG. 2 in which the present invention is not implemented.
Comparing the voltage difference Vpp from the positive peak to the negative peak, the starting voltage was reduced by 100 V in total.

FIG. 14 shows the structure of a lamp with a conductive film. A Nesa film, which is a conductive film, is provided on the inner surface of the glass tube, and a phosphor is applied on the Nesa film via a protective film. FIG. 15 shows a state before lighting of a lamp with a conductive film by a pseudo model. When a starting voltage is applied, the lamp with the conductive film is charged up with electrons one after another through the conductive film from both electrodes, thereby generating plasma in the lamp, forming a discharge path, and lighting the lamp. If the conductive film of a lamp with a conductive film is evenly distributed, the resistance value per unit length will be equal, but the conductive film will be uneven over the entire tube and the difference in resistance value per unit length will be different. If there is, a partial potential difference is generated. In particular, when the resistance in one direction is very large, such as those made by companies A and B in FIG. 17, a large potential difference portion occurs in the lamp, and electrons easily fly to a place where the potential difference per unit length is high. Become.

To summarize the above, the starting voltage applied to the electrode on the side where the resistivity of the conductive film is low is V1 with respect to the ground potential, and the starting voltage applied to the electrode on the side where the resistivity is high is V1. Assuming V2 with respect to the ground potential, | V1 |
By implementing the relationship of> | V2 |, it is possible to reduce the starting voltage as viewed from peak to peak value.

In general, ballasts have the greatest stress on the components at startup. Therefore, by suppressing the starting voltage, it is possible to reduce the withstand voltage of various components.
Further, when the ambient temperature shifts to a lower temperature side, the starting voltage for lighting the lamp increases, and this tendency becomes remarkable.

In this embodiment, the circuit configuration of the ballast does not have to be particularly limited, and is applied to all of the ballasts implemented in the relationship of | V1 |> | V2 |. Further, at the time of lighting, when the DC component _VDC is reduced, the crest factor can be improved. Although the present embodiment has been described with respect to a discharge lamp lighting device that generates a high frequency, a similar effect can be obtained with a copper-iron-type lighting device that operates at a commercial frequency.

(Embodiment 2) FIG. 3 shows a second embodiment of the present invention. One end of a lamp 2 with a conductive coating is connected to one output terminal of the discharge lamp lighting device 1 connected to the AC power supply AC, and the switch SW of the start-up correction circuit 3 falls to the illustrated terminal side during normal lighting. A lamp 2 with a conductive coating is connected to the other output terminal of the discharge lamp lighting device 1 via a switch SW.
Are connected to each other. At the time of starting, the switch SW of the starting correction circuit 3 is tilted to the terminal side opposite to the illustrated side, and the DC voltage _VDC and the resistor R are connected in series to the lamp 2. The discharge lamp lighting device 1 itself applies a sine wave output on which no DC component is superimposed to the lamp 2.

The direction in which the lamp 2 is connected is such that the DC voltage _VDC is superimposed on the side of the conductive film having the lower resistivity so that the relationship of the first embodiment is satisfied. Incidentally, in our investigation, the asymmetry of Company A and Company B shown in FIG. 17 was large, and the side where the lamp mark was printed was the side where the resistivity of the conductive film was small. With the above configuration, the starting voltage can be specifically reduced.

The operation of this embodiment will be described with reference to FIGS. FIG. 2 is a waveform of the lamp voltage at the time of starting when the DC component is not superimposed. In the figure, | X1 | = | X2 | = 500
V, and the peak-to-peak value of the starting voltage is Vpp = 10
00V. FIG. 1 shows a DC voltage V according to the present embodiment.
It is a waveform of the lamp voltage at the time of starting when _DC = 50V is superimposed. In the figure, | X1 | = | X2 | = 400V, and
| X3 | = | X4 | = 450 V, and the peak-to-peak value of the starting voltage is Vpp = 900 V. in this way,
By superimposing a DC voltage _{VDC of} 50 V, the starting voltage could be reduced by 100 V peak-to-peak.

(Embodiment 3) FIG. 4 shows a third embodiment of the present invention. This embodiment is based on a conventional example (Japanese Patent Laid-Open No. 9-153797).
2), a configuration in which the variable resistor Rx is used as the resistor R2 of the basic configuration circuit and the variable resistor Rx is made variable by the timer circuit IC3. The resistance value of the variable resistor Rx is set to an appropriate value so that the presence or absence of a filament can be detected at the time of preheating and lighting, and when the starting voltage is applied, the variable resistor Rx is set so that the relationship of | V1 |> | V2 | The value is controlled by the timer circuit IC3. At the same time, when the starting voltage is applied, the section is set as the filament disconnection detection inhibition section. The configuration of the timer circuit IC3 may be a general-purpose product or may use a time constant of CR, and thus a detailed description is omitted.

(Embodiment 4) In Embodiments 1 to 3 described above, it is necessary to specify the direction in which the lamps are connected in a catalog or specifications, which limits the use on the user side. Therefore, as a fourth embodiment of the present invention, a description will be given of a means which can implement the essence of the present invention without specifying the lamp insertion direction.

FIG. 5 macroscopically shows the starting voltage applied to the lamp, and shows the change in the envelope of the high-frequency voltage. The starting period for starting the lamp is section A and section B
It is divided into sections. When the starting voltage is viewed as a zero-to-peak value, | V0-p + |> | V0-p- | in section A and | V0-p + | <| V0-p- | in section B. Looking at the peak-to-peak value, Vpp (A) = |
V0−p + | + | V0−p− |, Vpp in section B
(B) = | V0−p + | + | V0−p− |, and Vp
It is assumed that p (A) = Vpp (B).

According to this embodiment, a lamp having a conductive coating which is not lit in the section A due to the directionality of the lamp is provided with a necessary zero-to-peak voltage in the section B.
Can be started. Thus, the effect as described in the first embodiment can be obtained.

As means for switching the starting voltage between the section A and the section B, for example, means for switching the direction of the DC voltage _VDC shown in FIG. 3 can be considered. Further, as a development of the present embodiment, there is a configuration in which the order of the A section and the B section is exchanged, and the A section and the B section appear many times during the starting period.

(Embodiment 5) FIG. 6 shows a fifth embodiment of the present invention.
Shown in FIG. 6 macroscopically shows the starting voltage applied to the lamp, and shows a change in the envelope of the high-frequency voltage. The difference from the fourth embodiment is that the starting voltage is not changed stepwise, but the positive and negative directions are switched with a smooth change.

When the voltage for starting the lamp is decomposed into an A section immediately after the application of the starting voltage, a B section in the middle of the application of the starting voltage, and a C section immediately before the end of the application of the starting voltage, the starting voltage in terms of a zero-to-peak value is obtained. Is | V0−p + |> | in section A.
V0-p- |, in section B, | V0-p + | = | V0-p
In the −− and C sections, | V0−p + | <| V0−p− |. In terms of peak-to-peak value, Vpp is
(A) = | V0-p + | + | V0-p- |, in section B Vpp (B) = | V0-p + | + | V0-p- |, and in section C Vpp (C) = | V0-p + | + | V0-p- |
And Vpp (A) = Vpp (B) = Vpp (C). Thereby, the effect as described in the first embodiment can be obtained.

The case where the change of the starting voltage by the present means is microscopically described will be described below. FIG. 7 is a microscopic view of the lamp voltage at the time of starting when the DC component is superimposed on the lamp. Ground by DC component
(Ground potential) is biased to the positive side. In this case, | X3 | = | X4 | and | X3 | + | X4
|> | X1 | + | X2 |.

FIG. 8 is a microscopic view of the lamp voltage when the switching duty of the inverter is unbalanced. The method of making the switching duty unbalanced is a general method for dimming and lighting, and the description is omitted. Here, unbalance control of the switching duty is performed so that the bias is biased to the negative side from the ground. In this case, | X5 |> | X1
|. The peak-to-peak value at this time is represented by Vpp (A)
And

FIG. 9 is a microscopic view of the lamp voltage when the DC component superposition of FIG. 7 and the effect of the switching duty imbalance control of FIG. 8 are combined. DC
Unbalance control of the switching duty is performed so that the component is superimposed and biased more positively than Ground and biased more negatively than Ground.
As a result, by correcting each other, | X6 | <| X
7 |, | X6 | + | X7 | = | X1 | + | X2 |. The peak-to-peak value at this time is defined as Vpp (B).

FIG. 10 shows a further enlargement of the switching duty imbalance control in FIG.
This is a microscopic view of the lamp voltage when | X7 |. In this case, the relationship of | X1 | <| X8 | can be created by canceling out the DC component in FIG. 7 and further correcting in the reverse direction. The peak-to-peak value at this time is Vp
Let p (C).

If the control is performed so that the period A in FIG. 7, the period B in FIG. 9, and the period C in FIG. 10 occur sequentially, the starting voltages Vpp (A), Vpp (B), and Vpp (C) as shown in FIG. Is obtained. As described above, if the unbalance control of the switching duty is used, the change of the duty can be easily controlled, so that it is very practical as a means for smoothing the change of the starting voltage.

By smoothing the alternating of the application of the starting voltage, it is possible to improve the dV / dt characteristics of the components of the discharge lamp lighting device, particularly the capacitor related to the starting, and to further reduce the size. Also in the present embodiment, similarly to the fourth embodiment, a configuration may be used in which the order of the A section and the C section is interchanged, or the A section and the C section appear many times during the starting period.

(Embodiment 6) FIG. 1 shows a sixth embodiment of the present invention.
It is shown in FIG. FIG. 11 macroscopically shows the starting voltage applied to the lamp. The difference from the fourth and fifth embodiments is that if the lamp is not turned on in one preheating start, intermittent oscillation is provided to provide a pause section, and in the next preheating start mode, V0-p in the direction opposite to the previous direction is set higher. It is characterized by. FIG.
As shown in (1), the lamp starting voltage before and after the suspension period is changed between the A section and the B section. When the starting voltage is viewed as a zero-to-peak value, in section A, | V0−p + |> | V0−
In the p- | and B sections, | V0-p + | <| V0-p- |. Looking at the peak-to-peak value, in section A, Vp
p (A) = | V0-p + | + | V0-p- |, and in section B, Vpp (B) = | V0-p + | + | V0-p- |, and Vpp (A) = Vpp (B). And

According to this embodiment, the lamp with the conductive coating which did not light in the section A due to the direction of the lamp is also supplied with the necessary V0-p voltage in the next section B after the pause period and the preheating period. , Can be started. Thus, the effect as described in the first embodiment can be obtained.

As means for switching the starting voltage between the section A and the section B, for example, means for switching the direction of the DC voltage _{VDC in} FIG. 3 can be considered. Further, as a development of the present embodiment, a configuration in which the order of the A section and the B section is exchanged, the A section is repeated several times, and then a transition is made to the B section, or a configuration in which the fourth and fifth embodiments are combined is possible. It is.

Embodiment 7 Hereinafter, a seventh embodiment of the present invention will be described. The components of the conductive film of the lamp with the conductive film described in Examples 1 to 6 are mainly composed of tin chloride. In this state of tin chloride, the resistance component tends to decrease depending on the ambient temperature and the electric field. That is, immediately after the start of use of the lamp, the extremely asymmetric resistance distribution such as company A and company B in FIG. 17 changes to a substantially flat resistance distribution as shown in FIG. 12 when the lamp is continuously used. . Therefore, the oscillation voltage of the discharge lamp lighting device is also adjusted to V
It is necessary to increase the difference between 0-p + and V0-p-. This is because the lamp used for a long time has no difference in resistance distribution as viewed from the center in the longitudinal direction, so that there is no place where the resistance component is high partially, and it is difficult to charge up electrons by concentrating the electric field. .

FIG. 13 shows a change in the starting voltage after a long time has elapsed according to the present embodiment. | V0-p + |> | V0-p- | in section A immediately after the start of use of the lamp, and | V0-p + | ≫ | V0-p- | in section B after long-term use. In terms of peak-to-peak value, Vpp is
(A) = | V0−p + | + | V0−p− |, and in section B, Vpp (B) = | V0−p + | + | V0−p− |, and Vpp (A) = Vpp (B) I have. As described above, as means for changing only the imbalance from the ground plane without changing the starting voltage Vpp,
The means described in the fifth embodiment is effective.

As a means for detecting the use time of the lamp, it is effective to check the change in the lamp voltage. Since the lamp voltage increases as the lamp usage time elapses, the lamp usage time can be detected by observing a change in the lamp voltage. Further, the usage time of the lamp may be detected by a timer circuit. According to this embodiment, reliable lamp lighting in consideration of the lamp usage time can be expected.

Embodiment 8 Hereinafter, an eighth embodiment of the present invention will be described. When starting a lamp with a conductive coating,
It has been mentioned that the charge-up of the conductive film is important. FIG. 16 shows an equivalent circuit of a lamp with a conductive film. As can be seen from this equivalent circuit, the electrode and the conductive film are connected by a capacitor having a distributed capacitance. It is known that this coupling capacitor has a capacitance of about several tens nF. Electrons that fly out of the electrode fly through the coupling capacitor to the conductive film, and are affected by the frequency applied to the discharge lamp. That is, the impedance of this coupling capacitor can be higher at low frequencies and lower at high frequencies. Therefore, when the lamp is started, the higher the frequency, the more the impedance of the coupling capacitor can be reduced, so that the conductive film can be effectively charged with electrons. However, judging from the standpoint of lamp efficiency, it is better that the bypass current to the conductive film that does not contribute to the emission of the lamp during normal stable lighting be small.

To summarize the above conditions, the frequency when the lamp is started is fosc, and the frequency when the lamp is stably operated is f.
When stb is set, fstb <fosc is satisfied, so that a discharge path can be reliably formed at the time of starting, the starting voltage can be reduced, and the lamp can be efficiently turned on at the time of normal lighting.

(Embodiment 9) Embodiments 1 to 8 show the characteristics of the discharge lamp ballast which contributes to the improvement of the starting of the lamp.
As a ninth embodiment, a lamp base and a dedicated socket will be described below. By making the shape of the lamp base asymmetrical left and right, it is designed to fit only into the dedicated socket,
The starting improvement can be performed more reliably. FIG. 18 illustrates an example of a lamp base, and FIG. 19 illustrates an example of a lamp socket. In the figure, 4 is a lamp pin, 5 is a projection, 6 is a lamp pin receiver, and 7 is a depression. In this example, a convex portion 5 for determining lamp directionality is provided on one of the lamp bases, and a recess 7 for determining lamp directionality is provided on one of the dedicated lamp sockets correspondingly. Insertion in the opposite direction can be reliably prevented. As described above, the lamp base is configured to be asymmetrical in the left and right directions, and is configured to be inserted only into the dedicated socket, so that the starting voltage applied to the electrode on the side where the resistivity of the conductive film is small is V1 with respect to the ground potential. Assuming that the starting voltage applied to the electrode on the side where the resistivity of the conductive film is higher is V2 with respect to the ground potential, the conditions for applying the starting voltage so that | V1 |> | V2 | can be reliably implemented.

[0050]

According to the first aspect of the present invention, there is provided a discharge lamp in which a lamp is provided with a resistance along a discharge path direction on a tube wall and whose resistance distribution is asymmetrical when viewed from the center of the lamp in the lamp longitudinal direction by an AC voltage. In the lighting device, if the starting voltage applied to the electrode having the lower resistivity is V1 with respect to the ground potential, and the starting voltage applied to the electrode having the higher resistivity is V2 with respect to the ground potential, | Since the starting voltage is applied so as to satisfy V1 |> | V2 |, the starting voltage of the lamp as viewed from peak to peak can be reduced, and the withstand voltage and the size of the electronic components used can be reduced. Can be implemented.

According to the second aspect of the present invention, since means for superposing and applying a DC component to an AC lamp voltage when starting the lamp is provided, a ballast circuit for outputting a voltage symmetrical with respect to the ground plane is used. Even in such a case, the effects of the present invention can be achieved. According to the third aspect of the present invention, since the height of the starting voltage is alternately applied to the ground plane, it is possible to cope with the reverse insertion of the lamp. According to the invention of claim 4, since a means for correcting the starting voltage according to the use time of the lamp is provided, even if the resistance distribution of the conductive film on the lamp tube wall changes with the lapse of the use time, The starting performance at the beginning of use can be maintained.

According to the fifth aspect of the present invention, since the frequency at the time of starting the lamp is set higher than the frequency at the time of stable lighting of the lamp, at the time of starting, the impedance of the distributed capacitance between the electrode and the tube wall resistance is lowered to start. In addition, during stable lighting, the impedance of the distributed capacitance between the electrode and the tube wall resistance is increased, and the bypass current that does not contribute to light emission can be reduced. According to the invention of claim 6, by making the shape of the bases at both ends of the lamp asymmetric, it is possible to insert the lamp only in the direction satisfying the condition of claim 1, and the effect of the present invention is reliably achieved. be able to.

[Brief description of the drawings]

FIG. 1 is a microscopic waveform diagram of a lamp voltage according to a first embodiment of the present invention.

FIG. 2 is a microscopic waveform diagram of a lamp voltage in a comparative example of the present invention.

FIG. 3 is a circuit diagram according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a third embodiment of the present invention.

FIG. 5 is a macroscopic waveform diagram of a lamp voltage according to a fourth embodiment of the present invention.

FIG. 6 is a macroscopic waveform diagram of a lamp voltage according to a fifth embodiment of the present invention.

FIG. 7 is a microscopic waveform diagram of a lamp voltage in a first section of a fifth embodiment of the present invention.

FIG. 8 is a microscopic waveform chart of a lamp voltage for explaining an operation of switching duty imbalance control used in Embodiment 5 of the present invention.

FIG. 9 is a microscopic waveform diagram of a lamp voltage in a second section according to the fifth embodiment of the present invention.

FIG. 10 is a microscopic waveform chart of a lamp voltage in a third section of Example 5 of the present invention.

FIG. 11 is a macroscopic waveform diagram of a lamp voltage in Embodiment 6 of the present invention.

FIG. 12 is an explanatory diagram showing the secular change of the lamp tube wall resistance in Embodiment 7 of the present invention.

FIG. 13 is a macroscopic waveform diagram of a lamp voltage showing a change in a starting voltage after a long time has elapsed in Example 7 of the present invention.

FIG. 14 is a partially cutaway front view showing the structure of a lamp with a conductive film, which is a compatible lamp of the present invention.

FIG. 15 is an explanatory diagram showing a starting mechanism of a lamp with a conductive film, which is a compatible lamp of the present invention.

FIG. 16 is an equivalent circuit diagram of a lamp with a conductive film, which is a compatible lamp of the present invention.

FIG. 17 is a characteristic diagram showing a resistance distribution of a lamp with a conductive film which is a compatible lamp of the present invention for each company.

FIG. 18 is a front view showing a structure of a lamp base used in Embodiment 9 of the present invention.

19A and 19B are diagrams showing a structure of a lamp socket used in Embodiment 9 of the present invention, wherein FIG. 19A is a front view, and FIG. 19B is a side sectional view.

FIG. 20 is a circuit diagram of a conventional discharge lamp lighting device.

FIG. 21 is a waveform chart showing a lamp voltage at the time of starting the conventional discharge lamp lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge lamp lighting device 2 Lamp with conductive coating 3 Start correction circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA02 BA03 BB01 BC01 BC03 BC07 DB03 EA01 EA02 EB01 EB05 GA02 GB12 GC04 HA06 HB03 3K082 AA04 BA05 BA06 BA24 BB05 BD03 BD26 BD32 BE04 CA09 CA37 FA08

Claims (6)

[Claims] 1. A discharge lamp lighting device in which a lamp has a resistance along a discharge path direction on a tube wall and whose resistance distribution is asymmetric when viewed from the center in the longitudinal direction of the lamp by an AC voltage. Assuming that the starting voltage applied to the first electrode is V1 with respect to the ground potential and the starting voltage applied to the electrode having the higher resistivity is V2 with respect to the ground potential, | V1 |> | V2 | A discharge lamp lighting device characterized by applying a starting voltage to the discharge lamp. 2. The discharge lamp lighting device according to claim 1, further comprising means for superimposing a DC component on an AC lamp voltage and applying the same when starting the lamp. 3. The discharge lamp lighting device according to claim 1, further comprising means for alternately changing the height of the starting voltage with respect to the ground plane. 4. The discharge lamp lighting device according to claim 1, further comprising means for correcting a starting voltage in accordance with a usage time of the lamp. 5. The discharge lamp lighting device according to claim 1, wherein the frequency at the time of starting the lamp is higher than the frequency at the time of stable lighting of the lamp. 6. The discharge lamp lighting device according to claim 1, wherein the bases at both ends of the lamp are asymmetric.