JPH0676979A - Dimming discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To provide a dimming discharge lamp lighting device having the capability of easily generating continuously variable optical output. CONSTITUTION:A dimming control section 11 dims a discharge lamp 3 via the control of a high frequency power supply 10 and impedance Z1. A lamp operation point selecting control section 12, upon receipt of a signal S1 for dimming the lamp 3 or a signal S2 of detected lamp current, sends a control signal to the section 11, so that an operation period at a stable operation point for low output and an operation period at a suddenly changing operation point are alternately repeated to continuously control optical output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimming discharge lamp lighting device.

[0002]

2. Description of the Related Art A conventional example of a dimming discharge lamp lighting device has a circuit configuration shown in FIG. This discharge lamp lighting device for dimming comprises a dimmer 1 and a ballast 2. In the dimmer 1, a switch element Q _{1 for} controlling the phase of a commercial AC power supply AC, and this switch element Q ₁ And a phase-controlled commercial AC power supply AC is input to the ballast 2 to control the output of the discharge lamp 3 such as a fluorescent lamp. A constant preheating power is supplied to the filaments f ₁ and f ₂ of the discharge lamp 3 by the preheating transformer FT.

In the ballast 2, a power factor improving capacitor C _ft is connected in parallel with the primary winding of the preheating transformer FT, and the secondary winding of the leakage type transformer LT is connected with a power factor improving capacitor C _m . It is connected to both ends of the discharge lamp 3 via. Further, when the light output becomes low, the choke L _p , the capacitor C _p , and the capacitor C _{p for} the purpose of maintaining stable lighting of the discharge lamp 3.
Commercial AC power supply AC with peaking circuit consisting of resistor R _p
A narrow pulse voltage is applied every half cycle of the discharge lamp 3
Is being applied to.

This conventional example has the following problems. That is, the noise from the ballast 2 is increased by the pulse voltage for lamp ignition applied every half cycle of the commercial AC power supply AC. In addition, there is a problem that the cost increases if soundproofing processing is performed to avoid the above problem. Furthermore, if the ballast 2 is installed away from the lighting fixture as a noise countermeasure, the electric wire from the ballast 2 to the discharge lamp 3 becomes longer,
Therefore, pulse attenuation occurs and light flicker occurs in the discharge lamp 3.

Another conventional example is Japanese Patent Laid-Open No. 61-2966.
There is one shown in No. 95. In this conventional example, a separately excited inverter circuit 4 is used as a ballast as shown in FIG.
The inductor L is used as a load of the other-excitation inverter circuit 4.
₀ , a capacitor C ₀ , and a discharge resonance circuit 3, and a re-strike detection circuit 5 detects re-strike of the discharge lamp 3 to change the operating frequency of the separately excited inverter circuit 4 through a control circuit 6. In addition, the firing pulse is applied to the discharge lamp 3 periodically by utilizing the characteristics of the load resonance circuit. Also in this case, there is a problem that noise is generated from the ballast as in the conventional example shown in FIG.

Therefore, as a means for solving the above problems, a DC voltage is superimposed on a high frequency voltage so that stable lighting is performed even when the discharge lamp has a low output.
No. 5572 is proposed by the present applicant. In this conventional example, since a periodic lamp firing pulse is not applied to the discharge lamp, the ballast is constructed with low noise.

[0007]

In a dimming discharge lamp lighting device such as Japanese Patent Application No. 1-75572, in which a ballast is constructed with low noise as described above, the following problems due to inverter control are also encountered. There is a point. This problem will be described in detail with reference to a dimming discharge lamp lighting device using the separately excited inverter circuit 4 shown in FIG. 19 (this device is the same as that shown in Japanese Patent Application No. 60-113716). To do.

First, the separately excited inverter circuit 4 used in the illustrated apparatus is a series inverter in which transistors Q ₁ and Q ₂ are connected in series, and the switching control thereof is performed by a control circuit 6. Diode D ₁ , D
Reference numerals ₂ are diodes for feedback current, respectively. Now DC power supply E
More energy is applied to the load circuit consisting of the inductor L ₁ , the capacitor C ₂ and the discharge lamp 3 by the inverter operation of the transistors Q ₁ and Q ₂ and the high frequency through the power supply capacitor C ₁ for cutting the direct current and required for the inverter operation. It is supplied as electric power.

Output control to the load is performed by transistors Q ₁ and Q
Controlled by ₂ on-time. That is, in a state where the transistors Q _1, Q ₂ of the OFF period T is constant as shown in FIG. 20 is carried out the control of the inverter output by varying the ratio of the transistors Q _1, Q ₂ of the on-time. Figure 2
0 (a) shows the maximum output state, and FIG. 20 (b) shows the state in which the on time of the transistor Q ₁ is long and the on time of the transistor Q ₂ is short to reduce the inverter output.

When the output current to the discharge lamp 3 is reduced, the lamp characteristics generally change as shown in FIG. That is, the lamp voltage V decreases due to the decrease of the lamp current I _La.
It shows a negative characteristic that _La increases. Then, the equivalent lamp impedance Z _La changes as shown in FIG. As a result, when the lamp impedance Z _La changes due to dimming, the load circuit of the separately excited inverter circuit 4 also changes.

For example, assuming that the impedance of the load circuit is Z _Ia in the circuit of FIG. 19, Z _Ia = [Z _La / (1 + ω ² C ₂ ² Z _La ² )] + jω {L ₁
-[(C ₂ Z _La ² ) / (1 + ω ² C ₂ ² Z _La ² )]} where ω = 2πf, f: the inverter operating frequency. As is clear from this relational expression, the imaginary number term that is the vibration term changes due to the change of the lamp impedance Z _La , and the vibration cycle also changes. Further, the magnitude of the impedance Z _Ia of the load circuit also changes.

When the change in the lamp impedance Z _La due to the dimming is smooth in FIG. 22, the change in the impedance Z _Ia of the load circuit is also smooth, and the light output continuously changes by controlling the inverter output. 23 to 25 show an example of the lamp characteristics of the discharge lamp that is practically used here. The characteristics shown in FIGS. 23 to 25 are for an FDL27 type discharge lamp. FIG. 23 shows an ambient temperature of 25 ° C. and a preheating current to the filament of 400 mA (a) and 500 mA.
It was measured by changing to (b). In addition, in FIG. 24, the preheating current to the filament is 300 mA at an ambient temperature of 5 ° C.
(A), 400 mA (b), and 500 mA (c). Further, FIG. 25 shows an ambient temperature of 10
Preheat current to filament at 200 ℃ (mA)
And 400 mA (b) and 500 mA (c) were measured.

As is apparent from FIG. 23, the fluctuation of the lamp impedance Z _La does not change smoothly as in the case of FIG. 22, but the fluctuation of the lamp voltage V _La with respect to the fluctuation of the lamp current I _La is large. . Furthermore, the rate of change greatly changes depending on the ambient temperature, and as the temperature becomes lower as shown in FIGS. 24 and 25, the change in the lamp impedance Z _La increases.

If the lamp impedance Z _La changes abruptly, the impedance _{Ia of} the load circuit changes abruptly. In other words, the fluctuation of the vibration term of the load circuit becomes sudden,
The fluctuation of the inverter output changes greatly, and the fluctuation of the optical output also increases. As a result, there is a problem that smooth dimming of the discharge lamp 3 becomes difficult during dimming by the inverter control.

In the circuit of FIG. 19, the load circuit constitutes a resonance circuit. However, even in a lighting device in which the load does not include the resonance circuit, the discontinuity of the light output due to the sudden change of the lamp impedance Z _La is not suitable for the use of the resonance circuit. It occurs slightly, but it occurs. The present invention has been made in view of the above problems,
It is an object of the present invention to provide a discharge lamp lighting device for dimming, which can eliminate the noise generation due to the lamp firing pulse and can easily continuously change the light output.

[0016]

According to a first aspect of the present invention, a discharge lamp, a high frequency power supply for supplying high frequency power to the discharge lamp, and a dimming for controlling the output of the high frequency power supply to dimm the discharge lamp. A dimming discharge lamp lighting device including a control unit performs dimming control using a plurality of lamp operation points.

According to a second aspect of the present invention, in the first aspect of the invention, the lamp operation point includes a lamp stable operation point. According to a third aspect of the present invention, in the first or second aspect of the present invention, there is provided a means for using a plurality of voltages applied to the discharge lamp and utilizing a plurality of lamp operation points. According to a fourth aspect of the present invention, in the third aspect of the invention, the voltage applied to the discharge lamp is set to be equal to or lower than the voltage required for starting and starting the discharge of the discharge lamp.

According to a fifth aspect of the present invention, the plurality of lamp operating points are repeated. The invention of claim 6 is characterized in that, in the invention of claim 1 or 2 or 3 or 4, the range in which the plurality of lamp operation points are utilized is set to a range below a predetermined dimming level. According to a seventh aspect of the invention, in the sixth aspect of the invention, the predetermined dimming level is determined by a dimming signal.

According to an eighth aspect of the invention, in the sixth aspect of the invention, the predetermined dimming level is determined by a lamp current. The invention of claim 9 is the same as the invention of claim 6,
The predetermined dimming level is determined by the lamp voltage. According to a tenth aspect of the invention, in the sixth aspect of the invention, the predetermined dimming level is determined by the lamp power.

According to an eleventh aspect of the present invention, in the first aspect of the present invention, there is provided means for controlling the plurality of lamp operating points by feedback control using a dimming signal and a lamp current, and the direction of the feedback control is decreasing Only the increasing direction is one direction.

[0021]

According to the structure of the first aspect of the invention, the light output of the discharge lamp can be continuously varied, and discontinuity of the light output can be avoided. According to the configuration of the invention of claim 2, in the invention of claim 1, since the lamp operation point includes the lamp stable operation point, the lamp firing pulse is unnecessary and noise generation can be eliminated.

According to the eleventh aspect of the present invention, in the first aspect of the present invention, there is provided means for controlling the plurality of lamp operating points by feedback control based on the dimming signal and the lamp current. Since only one direction of decreasing or increasing,
Flickering can be prevented when the dimming signal is changed smoothly, and continuous control of the light output can be performed.

[0023]

EXAMPLES Before explaining the examples, the basics of the present invention will be described.
The principle will be described. Lamp voltage V of discharge lamp_La−
Lamp current I_LaThe characteristics are as shown in Fig. 26.
In the light, when controlling the light output, the lamp impedance Z_LaBut
Relatively stable point A and lamp impedance Z_La
Point B (B₁, B ₂, ..., B_n,
...) is used to continuously control the light output of the discharge lamp.
Do your best.

For example, the operation period at the stable point A,
The operation period at the point B, which changes abruptly, is repeated as shown in FIG. 27 (which shows the time change of the lamp current I _La ),
By varying the output level in the operation period of point B, that is, the voltage applied to the discharge lamp, the light output control is continuously performed. As a method of continuously controlling the light output, the point B is changed to B ₁ , ..., B _n .
In addition to the method of changing the, as shown in FIG. 28, to set the operation period t ₁ of the point A at a predetermined period T _1, there is and how to change the operating period t ₁ of the point A. In this method, the point B to be combined has a low light output level as good as B _n , and is held constant for a period with respect to the point B.

Furthermore, a method of varying the lamp current output during the operation period at points A and B, and points A and B
To set the third operating point outside the operating period of
Further, there is a method in which the operation period of the point A is fixed and the operation period of the point B is temporally changed (the time of the point B is changed according to the light output). As described above, the present invention can be realized by various methods, but the point is to use a plurality of lamp operating points to realize the output continuity of the discharge lamp.

It should be noted that point A does not have to be the point where the light output is maximum, and therefore the voltage supplied to the lamp at point A need not be the lamp re-ignition pulse. That is, since the lamp re-ignition pulse is not used, noise generation can be solved and the continuity of light output can be achieved.
Furthermore, it is necessary that the repetition period of the operation period of point A and the operation period of B is at least such that the flicker of the light output cannot be perceived by the eyes. Further, it is not necessary to perform the above control at the point A or higher, that is, at the point where the lamp impedance Z _La is relatively stable.

The present invention will now be described in detail by way of examples based on the above-described principle of the present invention. (Embodiment 1) FIG. 1 shows a circuit configuration of this embodiment.
In the circuit of this embodiment, the discharge lamp 3 is connected to the output of the high frequency power source 10 composed of an inverter circuit via a current limiting impedance Z ₁ . The dimming controller 11 is the high frequency power source 1
The output of the discharge lamp 3 is controlled by controlling 0 and the impedance Z ₁ for current limiting. This output control is performed under the control of the dimming signal S ₁ and the lamp operation point switching control unit 12 from the outside.

Lamp operating point switching control unit 12
Receives the dimming signal S ₁ or the lamp current (or lamp voltage) detection signal S ₂ and generates a control signal to be supplied to the dimming controller 11. DC power supply 13 is Impedance Z
_The DC voltage is superimposed on the high frequency voltage via ₂ so that stable lighting can be performed even when the discharge lamp 3 has a low output.
Controlled with ₂ . Of course, the DC power supply 13 and the impedance Z ₂ need not be provided.

Thus, in this embodiment, the lamp operation port is
When the output is low, the output switching controller 12 works
As mentioned above, the stable operation period at point A
The operation period at the changing point B is alternately repeated.
The light output is continuously controlled. FIG. 2 shows the present embodiment.
A concrete circuit is shown. This circuit shows a transistor Q.₁,
Q₂And diode D for feedback current₁, D₂And Conden
SA C₃, C_FourSo-called half-bridge type inverter using
The circuit constitutes the high frequency power supply 10. Transistor
Q₁, Transistor Q₂Is a control signal from the dimming controller 11.
And drive through the drive units 14 and 15
It has become. In the figure, reference numeral 16 is a control signal to the drive unit 14.
It is an insulating signal transmission part for giving the edge. Also L₁Is
Inductor, C _FiveIs a preheating capacitor, E is a DC power supply
is there.

The driving units 14 and 15 and the transistor Q ₁ ,
A control circuit for separately controlling Q ₂ is disclosed in Japanese Patent Laid-Open No. 61-61296.
Known circuits found in Japanese Patent Application No. 695 and Japanese Patent Application No. 63-128695 are used. Now, the dimming control unit 11 controls the dimming signal S ₁
In response to this, dimming control is performed by changing the operating frequency of the high frequency power supply 13, and its operation is as follows.

The discharge lamp 3 is shown in FIG.
The operating frequency f is increased up to the point A where the lamp impedance Z _La shown in (3) is relatively stable, the current limiting impedance is increased, and the lamp current I _La is decreased.
When the operating area in which the lamp impedance Z _La changes abruptly after passing the point A, as shown in FIG.
Lamp current I _LaA at point A with constant
Control is performed by receiving a control signal from the lamp operation point switching control section 12 to alternately switch the operation period during which the lamp current I _LaB flows and the period during which the lamp current I _LaB flows at the point B. Here, the operation period t at which the lamp current I _LaA at point A is flown
By making variable, output control is continuously performed. Point B is an operating point where the lamp output Z _La is relatively stable and the lamp impedance Z _La is relatively stable. Note that fa and fb represent the inverter operating frequencies at points A and B, and V _LaA and V _LaB represent the lamp voltages at points A and B, respectively.

The dimming signal S ₁ given to the dimming control unit 11 and the lamp operation point switching control unit 12 is a DC voltage that varies according to the set dimming level, and the lamp operation point switching control unit 12 detects the point A. Can be done easily. That is, as shown in FIG. 5, the signal level es of the dimming signal S ₁ and the point A
The point A can be detected by comparing with the comparator CP the reference voltage Vref set corresponding to the above.

Lamp operation point switching control unit 12
Is a control for switching the operating frequency by a period generating timer (not shown) that receives this detection signal and a timer (not shown) that determines the operating period t in conjunction with the signal level es of the dimming signal S _1. The signal is given to the dimming control unit 11. (Embodiment 2) FIG. 6 shows a circuit of this embodiment. In this circuit, a transistor Q ₁ which uses a direct current obtained by rectifying and smoothing a commercial AC power supply AC with a diode bridge DB and a capacitor C ₆ , Q ₂ is used as the high frequency power source 10 which is a self-excited half-bridge inverter.

The high frequency power supply 10 supplies the output to the resonance load circuit of the discharge lamp 3, the capacitor C ₇ , and the inductor L ₂ via the capacitor C ₈ for cutting the direct current and the power supply. High frequency power source 10 is turned on in a base current flows through the transistor Q ₂ when the voltage of the capacitor C ₉ to rise from the power-on trigger element Q ₇ exceeds the breakover voltage of the trigger element Q ₇ is turned, the turned Capacitor C ₈ , C ₇ , inductor L ₂ ,
A current flows in the circuit of the primary winding n ₁ of the current transformer CT and the transistor Q ₂ and thereafter the feedback winding n of the current transformer CT.
_The secondary outputs of ₂ and n ₃ alternately turn on and off the transistors Q ₁ and Q ₂ , and the high frequency power supply 10 continues to oscillate.

On the other hand, in the dimming control section 11, the output of the comparator CP ₁ becomes "L" from the power-on until the voltage of the capacitor C ₁₀ reaches a constant level. That is, comparator C
The inverting input terminal of P ₂ is set to "L". On the other hand, comparator C
Transistor Q ₆ which controls the charging and discharging of the capacitor C ₁₁ which is connected to the non-inverting input terminal of the P ₂ is given base current is turned on by the activation of the above, the transistor Q ₅ is turned off. Therefore, the capacitor C ₁₁ is charged, and the output of the comparator CP ₂ becomes "H". From this "H" transistors Q _4, Q ₃ is turned on to cut the base current of the transistor Q _2, Q _6. When the transistor Q ₆ is turned off, the transistor Q ₅ is turned on to discharge the capacitor C _11.

By repeating the above operation, the transistor Q
₂ is shortened and the discharge lamp 3 has a capacitor C ₇
Sufficient preheat current through. Eventually, the dimming control unit 11
When the capacitor C ₉ is charged until it exceeds the divided voltage of the resistors R ₁ and R ₂ , the output of the comparator CP ₁ becomes “H”.
Flip to. Therefore, the time required for the voltage of the capacitor C ₁₁ to exceed the voltage applied to the inverting input terminal of the comparator CP ₂ changes depending on the voltage applied to the inverting input terminal. That is, the ON period of the transistor Q ₂ of the high frequency power source 10 controlled by the transistors Q ₄ and Q ₃ can be controlled by the voltage applied to the inverting input terminal of the comparator CP ₂ , and the discharge lamp 3 can be controlled by changing the ON period. It is possible to control the output to and dimming.

The dimming control unit 11 is provided with a comparator CP ₃ for comparing the signal level es of the dimming signal S ₁ with the reference voltage Ea set in advance corresponding to the point A, and exceeds the point A. Dimming signal S in stable region
_At the signal level es of ₁ , the output of the comparator CP ₃ is set to “L” to turn on the transistor Qx, and the dimming level es is applied to the inverting input terminal of the comparator CP ₂ through the transistor Qx, and the transistor Q ₂ of the high frequency power supply 10 is turned on. The on period is set.

When the level es of the dimming signal S ₁ falls below the reference voltage Ea, the output of the comparator CP ₃ is set to "H", the transistor Qx is turned off, and the level es of the dimming signal S ₁ is changed to the comparator CP. _The application to the inverting input terminal ₂ is stopped, and at the same time, a trigger signal is applied to the timer TM which is the astable multivibrator of the lamp operation point switching control unit 12 to operate. Timer TM
Produces an inverted Q output and a Q output as shown in FIG.
Therefore, during the period t when the inverted Q output is "L", the reference voltage Ea corresponding to the point A is applied to the inverting input terminal of the comparator CP ₂ via the transistor Qy, and the dimming output corresponding to the point A is discharged from the high frequency power source 10. Give to lamp 3. On the other hand the voltage Eb of the Q output corresponding to previously point B in the period (T-t) of the "L" output is set so as to give to give to the inverting input terminal of the comparator CP ₂ through transistor Qz to point A A corresponding output is applied to the discharge lamp 3 from the high frequency power supply 10.

This makes it possible to control the light output continuously and smoothly as in the first embodiment. As the high frequency power source 10, an inverter of one-stone type, full bridge type, push-pull type or the like may be used. (Embodiment 3) This embodiment corresponds to the invention of claim 11 and uses the following principle. That is, when a dimming signal is applied to the dimming discharge lamp lighting device and the light output of the discharge lamp is controlled by the output based on the dimming signal, there are the following problems.

That is, as shown in FIG. 8, when the dimming signal is gradually changed, the light output (lamp current I _La ) changes sharply from β to γ around the point α. To present points. In order to avoid this light output discontinuity point, feedback control by detecting a lamp current or the like has been conventionally used. FIG. 9 shows a dimming discharge lamp lighting device 1 using this feedback control.
4 shows the configuration of the feedback control system of 4,
In this illustrated example, the case where the dimming signal S ₁ is given at the level es of the DC voltage is shown, and the light output of the discharge lamp 3 with respect to the dimming signal level es (here, the lamp current detection circuit 15
From the detected value ek) to Δe (= ek-es), and the difference between this Δe and the dimming signal level es (e ₀ =
By taking es-KΔe), a negative feedback control system is constructed. According to this configuration, FIG.
The optical output converges with respect to the target value (a) indicated by 0. However, a time delay occurs in the control circuit system, and α shown in FIG.
In the vicinity of the abrupt change of the optical output like a point, the optical output fluctuates due to feedback, and a flicker phenomenon appears.

In view of this point, in the present embodiment, the light output (lamp current I _La ) is shown in FIG.
As shown in FIG. 1, control is performed by applying feedback only in the decreasing direction. FIG. 12 shows the configuration of the present embodiment. The discharge lamp 3 is connected to the dimming discharge lamp lighting device 17 using a high frequency power source via the lamp current detection circuit 18, and the lamp current detection circuit 18 outputs the lamp current. The detection value ek is given to the control circuit 16, and the control circuit 1
I am going to put on a food bag through 6.

The control circuit 16 controls Δe (= ek-e
s) calculating unit determining unit 16a and this calculating unit 16a
Difference Δe between the output Δe and the dimming signal level es (e ₀ = es
-KΔe) for calculating the optical output (lamp current I _La ) to the target value only when positive Δe is calculated.
The control output for applying feedback so as to converge is given to the dimming discharge lamp lighting device 17.

A stable lamp operation point (area including the above-mentioned point A) where the lamp current I _La is relatively large
In the same manner as in the conventional case, the calculation unit 16a outputs Δe to the calculation unit 16b regardless of whether Δe is positive or negative, and the lamp current I
_{At the} lamp operation point where _La is small (the area including point B described above), the calculation unit 16a calculates only positive Δe.
It is output to b, and the feedback is applied only in the direction in which the light output (lamp current I _La ) is reduced.

FIG. 13 shows this control, and as shown in the figure, the lamp current I _La and the dimming signal level es (even if the dimming signal level es remains unchanged, are repeated during the operation period of points A and B). , Or may be partially changed in order to freely create the target value curve.) Randomly based on comparison with. It is also conceivable to change the value of the lamp current I _La in each operation period according to the level of the light output.

FIG. 14 shows a circuit embodying the above-mentioned structure. This circuit is similar to the circuit of FIG.
_The high frequency power supply 10 is configured by a so-called half bridge type inverter circuit using ₁ , Q _2, feedback current diodes D ₁ and D _2, and capacitors C ₃ and C ₄ . The transistors Q ₁ and Q ₂ receive the control signal from the dimming control unit 11 and are driven by the driving units 14 and 15. Reference numeral 16 is an insulation signal transmission section for insulatingly applying a control signal to the drive section 14. The lamp current detection circuit 18 is inserted between the discharge lamp 3 and the current limiting inductor L ₁ .

The control circuit 16 has a circuit corresponding to the arithmetic unit 16b in the dimming control unit 11 and has an arithmetic unit 16a.
Is provided separately from the dimming control unit 11. A control circuit for separately controlling the driving units 14 and 15 and the transistors Q ₁ and Q ₂ is disclosed in Japanese Patent Application Laid-Open No. 61-6129695 and Japanese Patent Application No.
A known circuit found in 3-128695 or the like is used.
The dimming control unit 11 is a well-known unit that performs the dimming control by changing the operating frequency of the high frequency power source 13 by receiving the dimming signal S ₁ like the circuit of FIG. 2, and performs the dimming control by the above-mentioned feedback. As a result, the light output can be continuously controlled without flicker.

(Embodiment 4) FIG. 15 shows a circuit of this embodiment.
You The circuit of this embodiment has a basic high frequency power
Since the circuit for performing the dimming control is the same as that of the second embodiment,
Only the characteristic points of this embodiment will be described. First the lamp
The flow detection circuit 18 is a preheating circuit for the discharge lamp 3 and a lamp power source.
Current circuit with two primary windings of opposite polarity inserted in the current circuit.
Lance CT ₀The secondary output of the resistor R_Ten, R₁₁Partial pressure with
The dimming control unit 1 sets the partial voltage output of the lamp as the lamp current detection value ek.
1 computer CP_FourTo give to the inverting input terminal of
ing. Zener diode ZD₀Is lamp current detection
This is for keeping the value ek below a certain level.
Comparator CP of dimming controller 11_FourIs the dimming signal level
Input es to the non-inverting input terminal to detect the lamp current detected value ek
To compare with.

Therefore, the lamp current I_LaHas a large stable movement
At the production point, ek <es, so the comparator
CP_FourSets the output to "H" and turns on the transistor Qa,
The transistor Qb is turned off, and the dimming signal level es
Comparator CP through the transistor Qa₂Anti
Give it to the input end. And lower the dimming signal level es
Then, if the dimming level is lowered, unstable operation will eventually occur.
The point is that ek> es. This
When the comparator CP_FourInverts the output to "L",
The transistor Qa is turned off and the transistor Qb is turned on.
Therefore, [R₁₂/ (R₁₂+
R₁₃)] × es value is used as a dimming signal level
CP₂It is supposed to give to the inverting input terminal of
(Lamp current I_La) Feedback in the direction of decreasing
It is controlled.

It is necessary to set the response speed of this feedback control to a time equal to or shorter than the time of generation and disappearance of excited electrons in the discharge lamp 3. Further, in the circuit of the above embodiment, the feedback control section is performed in the entire dimming region, but the feedback control may be performed only in the section where the light output changes abruptly as shown in FIG.

Further, as the high frequency power source 10, an inverter of one-stone type, full bridge type, push-pull type or the like may be used. In the third and fourth embodiments, the feedback control at the unstable operation point is performed only in the direction of decreasing the light output, but it may be performed only in the direction of increasing the light output. However, in order to smoothly carry out the continuous change of the light output, it is preferable to reduce the lamp current I _La to reduce the light output.

[0051]

According to the first aspect of the present invention, there is provided a discharge lamp, a high frequency power source for supplying high frequency power to the discharge lamp, and a dimming control section for controlling the output of the high frequency power source to dimm the discharge lamp. In the provided dimming discharge lamp lighting device,
Since the dimming control is performed by using a plurality of lamp operation points, the light output of the discharge lamp can be continuously varied, and the discontinuity of the light output can be avoided.

Particularly, in the invention of claim 2, in the invention of claim 1, since the lamp operation point includes the lamp stable operation point, there is an effect that a lamp firing pulse is unnecessary and noise can be eliminated. is there. According to the invention of claim 11, in the invention of claim 1, there is provided means for controlling the plurality of lamp operation points by feedback control by a dimming signal and a lamp current, and the direction of the feedback control is decreased or increased. Since only one direction is used, there is an effect that flicker can be prevented when the dimming signal is smoothly changed, and continuous control of the light output can be performed.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a first embodiment of the present invention.

FIG. 2 is a specific circuit configuration diagram of the above.

FIG. 3 is a characteristic diagram for explaining the operation of the above.

FIG. 4 is a time chart for explaining the above operation.

FIG. 5 is a circuit diagram of a main part of the above.

FIG. 6 is a specific circuit diagram of the second embodiment of the present invention.

FIG. 7 is a time chart for explaining the operation of the timer TM of the above.

FIG. 8 is a relationship diagram of optical output-dimming signal for explaining the principle of the invention of claim 11;

FIG. 9 is a conventional circuit configuration diagram corresponding to the above feedback control.

FIG. 10 is a relational diagram of optical output and dimming signal for explaining the problem of the circuit configuration of FIG. 9;

FIG. 11 is a relational diagram of optical output-dimming signal for explaining the feedback control of the invention of claim 11;

FIG. 12 is a circuit configuration diagram of a third embodiment corresponding to the invention of claim 11;

FIG. 13 is a time chart for explaining the above operation.

FIG. 14 is a specific circuit configuration diagram of the above.

FIG. 15 is a specific circuit diagram of the fourth embodiment corresponding to the invention of claim 11;

FIG. 16 is a relationship diagram of an optical output and a dimming signal for explaining another feedback control of the invention of claim 11;

FIG. 17 is a circuit configuration diagram of a conventional example.

FIG. 18 is a circuit configuration diagram of another conventional example.

FIG. 19 is a circuit configuration diagram of another conventional example.

FIG. 20 is a time chart for explaining the above operation.

FIG. 21 is a lamp current-lamp voltage relationship diagram for explaining the above operation.

FIG. 22 is a lamp current-lamp impedance relationship diagram for explaining the above operation. is there.

FIG. 23 is a lamp current-lamp voltage relationship diagram of the discharge lamp.

FIG. 24 is a lamp current-lamp voltage relationship diagram of the discharge lamp.

FIG. 25 is a lamp current-lamp voltage relationship diagram of the discharge lamp.

FIG. 26 is a lamp current-lamp voltage relationship diagram for explaining the principle of the present invention.

FIG. 27 is an explanatory diagram of an example of a control method used in the above.

FIG. 28 is an explanatory diagram of another example of the control method used in the above.

[Explanation of symbols]

3 Discharge lamp 10 High frequency power supply 11 Dimming control unit 12 Lamp operation point switching control unit S ₁ Dimming signal S ₂ Lamp current detection signal

Claims (11)

[Claims] 1. A dimming discharge lamp comprising a discharge lamp, a high frequency power supply for supplying high frequency power to the discharge lamp, and a dimming control section for controlling the output of the high frequency power supply to dimm the discharge lamp. In a lighting device, a dimming discharge lamp lighting device is characterized in that dimming control is performed by utilizing a plurality of lamp operation points. 2. The discharge lamp lighting device for dimming according to claim 1, wherein the lamp operation point includes a lamp stable operation point. 3. The dimming discharge lamp lighting device according to claim 1, further comprising means for utilizing a plurality of lamp operating points by using a plurality of voltages applied to the discharge lamp. 4. The dimming discharge lamp lighting device according to claim 3, wherein the voltage applied to the discharge lamp is set to be equal to or lower than a voltage required for starting and discharging the discharge lamp. 5. The dimming discharge lamp lighting device according to claim 1, wherein the plurality of lamp operating points are repeated. 6. The dimming discharge lamp lighting device according to claim 1, wherein the range of utilizing the plurality of lamp operating points is set to a range below a predetermined dimming level. 7. The discharge lamp lighting device for dimming according to claim 6, wherein the predetermined dimming level is determined by a dimming signal. 8. The discharge lamp lighting device for dimming according to claim 6, wherein the predetermined dimming level is determined by a lamp current. 9. The discharge lamp lighting device for dimming according to claim 6, wherein the predetermined dimming level is determined by a lamp voltage. 10. The discharge lamp lighting device for dimming according to claim 6, wherein the predetermined dimming level is determined by lamp power. 11. A means for controlling the plurality of lamp operating points by feedback control using a dimming signal and a lamp current, wherein the feedback control direction is only one direction of decreasing or increasing. The discharge lamp lighting device for light control according to claim 1.