EP0063168A1 - High pressure discharge lamp apparatus - Google Patents
High pressure discharge lamp apparatus Download PDFInfo
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- EP0063168A1 EP0063168A1 EP19810103046 EP81103046A EP0063168A1 EP 0063168 A1 EP0063168 A1 EP 0063168A1 EP 19810103046 EP19810103046 EP 19810103046 EP 81103046 A EP81103046 A EP 81103046A EP 0063168 A1 EP0063168 A1 EP 0063168A1
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- European Patent Office
- Prior art keywords
- current
- lamp
- discharge tube
- high pressure
- voltage
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/39—Controlling the intensity of light continuously
- H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
Definitions
- This invention relates to an improvement in a high pressure discharge lamp apparatus such as a high pressure mercury lamp apparatus, a high pressure sodium lanp apparatus, or a high pressure metal-halide lamp apparatus.
- the present invention especially concerns an improvement in a high pressure discharge lamp apparatus of the type comprising a high pressure discharge tube, a current limiting device, for instance a choke coil, and a pulse generator output terminals of which are connected in parallel to the electrodes of the discharge tube for lighting the tube with a lamp voltage nearly equal to a power source voltage.
- a current limiting device such as a choke coil and a discharge tube are connected in series across a power source.
- a voltage of the power source should be maintained over 1.5 times a voltage of the discharge tube for preventing an extinction of ignition in the tube. Therefore a voltage drop across the current limiting device is high, and a power loss at the current limiting device is rather large. Accordingly, a dimension and a weight of the current limiting device become undesirably large.
- a pulse generator may be provided in a manner to give pulses to the discharge tube.
- the lamp voltage can be selected so high as nearly equal to the power source voltage.
- the conventional discharge lamp apparatus having a pulse generator as above-mentioned still has the following problems: (1) In a case that the high pressure discharge lamp is ignited in every cycle of the power source voltage by impressing of pulse by the pulse generator, a lamp voltage can be selected so high as nearly equal to the power source voltage, and an impedance of the current limiting device can be selected small. But, when the discharge tube starts to ignite, a lamp current grows excessively large, and therefore the impedance of the discharge tube such as the choke coil becomes almost zero for a magnetic saturation due to the overcurrent. Therefore, for avoiding the magnetic saturation, the choke coil as the current limiting device should be designed so as to have relatively large sectional area of a core thereof, thereby making the current limiting device large in dimension and expensive in cost.
- FIG. 1 In order to solve the abovementioned problem, another conventional high pressure discharge lamp apparatus has been devised as shown in FIG. 1, whrerin a current limiting device 2 such as a choke coil, an auxiliary current limiting device 5 and a discharge tube 3 are connected in series across a power source 1.
- the auxiliary current limiting-device 5 of a relatively large size has more large capacity of current limitation than that of the current limiting device 2.
- a semiconductor switching device 6 is connected in parallel to the auxiliary current limiting device 5.
- a pulse generator 4 is connected in parallel to the discharge tube 3 for supplying reignition pulses to the discharge tube 3.
- a duty time of the current limiting device 5 is controlled by firing angle controlling action of the semiconductor switching device 6 in such manner that at the stating the duty time of the switching device 6 is very small and at the steady lighting state the duty time is very large, so that effectively the auxiliary current limiting device 5 is substantially shot-circuited by the switching device 6 at a steady lighting state of the lamp. Therefore a lamp current may be maintained for the same degree between at a steady lighting state and at a starting trangent state.
- the pourpose of the invention is to provide a high pressure discahrge lanp apparatus having a pulse generator to impress pulses across the discharge tube for allowing selecting a lamp voltage very close to a power source voltage, and having no auxiliary current limiting device like the device 5 of the conventional high pressure discharge lamp apparatus shown in FIG. 1.
- the high pressure discharge lamp apparatus of the present invention comprises a discharge tube and a current limiting device connected in series, an over-current protecting device is further connected in series to said discharge tube, over-current protecting device being controlled of its firing angle responding to an output of a current detection circuit, and a pulse generator is further connected in parallel to the discharge tube.
- FIG. 2 A fundamental apparatus embodying the present invention is shown in FIG. 2.
- a current limiting device 2 and an over-current protecting device 11 are connected in series with a discharge tube 3 across a power source 1.
- a pulse generator 4 is connected in parallel to the discharge tube 3 for supplying reignition pulses to the discharge tube 3.
- a lamp current detecting circuit 9 for detecting a lamp current and giving control signal to the over- current protecting device 11 is connected in parallel to the discharge tube 3.
- the pulse generator 4 is for preventing extinction of the tube and allowing a selection of a lamp voltage high enough close to a voltage of the power source 1, by supplying the .reignition pulses to the discharge tube 3, during a period from near the zero-cross point of the voltage of power source 1 to a stated point for from the zero-cross point in every cycle of the voltage of power source 1.
- the reignition pulses extinction of the ignition in the discharge tube 3 may be effectively avoided even in the zero current period in each cycle of the lamp current.
- FIG. 3 shows an apparatus embodying the present invention which uses a semiconductor switching device 11 as the over-current protector and uses a lamp current detecting circuit 9, which in actual circuit is a voltage detection circuit which outputs a signal to indicate a voltage of the discharge tube 3 and has a specified relation with the lamp current, is shown in FIG. 3.
- a current limiting device 2 of passive element device such as a choke coil
- the semiconductor switching device 11 as the over-current protector and a discharge tube 3 are connected in series across a power source 1.
- a pulse generator 4 for impressing reignition signal on the discharge tube 3 is connected in parallel to the latter.
- the lamp current detecting circuit 9 is connected in parallel to the discharge tube 3.
- a firing angle controlling circuit 10 is disposed so as to receiving an out-put signal of the lamp current detecting circuit 9 and supply a firing angle controlling signal to the switching device 11.
- a firing angle of the switching device 11 is controlled based on a relation between the lamp current and the lamp voltage which is detected in the lamp current detecting circuit 9. And the switching device 11 controls the firing angle, hence effective value of the current of the discharge tube 3 from the power source 1, and thereby protects an over-current at the starting transient state.
- the pulse generator 4 supplies reignition pulses in every cycles to the discharge tube 3 at least during the zero current period of the lamp current in order for avoiding an extinction of the discharge tube 3 due to zero current period both in starting transient state and steady lighting state.
- a lamp voltage V La and a lamp current I La of the high pressure discharge tube show the curves as shown in FIG. 4.
- Z La which is relatively small at incipient period of starting of lighting in the discharge tube wherein a vapour pressure in the tube is relatively small.
- the lamp current I La that is a current through the choke coil, decreases at the time lapses, and simultaneously the lamp voltage V La increases as shown in FIG. 4. Accordingly, the amount of the lamp current I La can be known by detecting the lamp voltage V La based on abovementioned. relation between the current I La and the voltage V Lao Consequently, the lamp current I La can be controlled by detecting the lamp voltage V La primarily.
- FIG. 5 is a circuit diagram of the apparatus of the present invention.
- FIG. 7A and FIG. 7B are wave-form chart of various parts of the circuit shown in FIG. 5.
- a voltage across the discharge tube 3 is impressed to the lamp current detecting circuit 9 which detects a lamp current by detecting a lamp voltage. That is, in present invention, the lamp current is easily detected by a simple circuit as shown in FIG. 5.
- the lamp current detecting circuit 9 the lamp voltage having a certain relation with the lamp current as shown in FIG.
- the firing angle controlling circuit 10 is given to the firing angle controlling circuit 10, wherein the power source voltage V S is. led through a resistor R 4 , DB 1 and R 5 , and then is level clipped by a regulate diode D 1 , whose voltage wave form V 1 is shown in F I G . 7A.
- the voltage wave-form V 1 is supplied to an anode of PUT (programmable unijunction transistor) Q 2 through a resistor R 6 .
- the transistor Q 1 maintains off state as abovementioned, and hence the voltage of wave-form V 1 is supplied to a capacitor C 2 for charging only through the resistor R 6 .
- a voltage wave-form V 2 of the capacitor C 2 is formed as shown in FIG. 7A.
- the voltage of wave-form V 1 is divided by resistors R a and R 9 , and the divided voltage is impressed to a gate of the PUT Q 2 .
- the voltage V 2 of the capacitor C 2 grows up and comes above the voltage impressed to the gate of the PUT Q 2 , hence the PUT Q 2 turns on. Consequently the electric charge in the capacitor C 2 discharges through the PUT Q 2 .
- a trigger pulse V 3 as shown in F I G . 7A is produced across both ends of a resistor R 10 .
- a thyristor Th is triggered by the pulses V 3 impressed through a resistor R 11 .
- the thyristor Th turns on, both out-put ends of the diode brindge circuit DB 1 are short-circuited by the thyristor Th, and hence the voltage V 1 becomes zero, and then triggering action of the PUT Q 2 is stopped.
- the PUT Q 2 turns on at a firing angle corresponding to the time constant resistor R 6 and the capacitor C 2 , and therefore, the thyristor Th turns on by receiving the triggering pulses V 3 impressed to the gate thereof through the resistor R 11 .
- the thyristor Th maintains "on" state until a forward current thereof becomes lower than a holding current of the thyristor Th at a timing near an end of every positive half cycle of the power source voltage V S .
- a gate current flows in the triack TC as a switching device 11 through the path of: power source 1 - current limiting device 2 - discharge tube 3 - gate of the triack TC - diode D 2 - thyristor Th - diode bridge circuit DB 1 - power source 1.
- the gate current of the triack TC flows through the path of: power source 1 - diode bridge circuit DB 1 - thyristor Th ⁇ diode D 3 - gate of the triack TC discharge tube 3 current limiting device 2 - power source 1.
- the triack TC is "on" during the while the gate currents exist. Accordingly, a main load current I La of the triac k TC is appropriately controlled by the firing angle controlling circuit 10 which determines a firing angle 0 1 of the triack TC as shown in FIG. 7A.
- the main load current I La has a zero current period in each cycle, by means of the reignition pulses V P are supplied to the discharge tube 3 at least during the zero current period in each cycle of the main load current ILa.
- the lamp voltage increases, and also the base potential of the transistor Q 1 rises, so that the transistor Q 1 turns on.
- a series circuit of the resistor R 7 and the internal resistance (collector-emitter resistance) of the on-state transistor Q 1 is connected in parallel to the resistor R 6 , and therefore a charging time of the capacitor C 2 is shortened. Accordingly a time till the PUT Q 2 turns on is shortened, and therefore the time phase of trigger pulses V 3 across the resistor R 10 is led, hence the firing angle of the triack T C becomes very small as shown by ⁇ 2 ( ⁇ 2 ⁇ 1 ) in FIG. 7B.
- an apparatus of present invention has a pulse generator 4 and a switching device as an over-current protecting device, and the lamp current at the starting transient state is suppressed by over-current protecting device nearly equal to the lamp current at the steady lighting state, preventing the extinction by the reignition pulses from the pulse generator 4.
- the current limiting device 2 can be designed small enough and further a loss therein can be satisfactorily diminished.
- FIG. 6 is a detailed circuit diagram of the pulse generator 4, and FIG. 8 is a wave-form chart of various parts of the circuit shown in FIG. 6.
- the pulse generator 4 issues ignition pulses to the discharge tube 3, and the discharge tube 3 is ignited. Operation of the pulse generator 4 after starting of ignition is elucidated hereafter separating in two parts. First part is for the positive half cycle period of the power source voltage V S and the second part is for the negative half cycle period of the power source voltage V s .
- the voltage V s is rectified and level clipped by a power source rectifying circuit 12a consisting of a diode D 4a , a resistor R 12a , and a regulate diode D 5a .
- An output voltage of the power source rectifying circuit 12a that is a voltage of a point C in FIG. 6 is shown by a wave-form C of FIG. 8.
- a voltage of the wave-form C is supplied to an oscilating circuit 14a and to an oscillation control circuit 13a.
- the voltage of the wave-form C is impressed to an integration circuit consisting of a resistor R 17a and a capacitor C 4a , then an integrated voltage of the capacitor C 4a at a point D in FIG. 6 is impressed to the base of a transistor Q 5a .
- a voltage wave-form D at the point D' is shown in FIG. 8.
- a comparator consisting of two transistors Q 5a , Q 6a , and three resistors R 18a , R 19a , R 20a is formed in the oscillation control circuit 13a.
- a voltage of the point C is divided by resistors R 21a and R 22a and impressed to the base of the transistor Q 6 in the comparator.
- a duty time of a wave-form E the oscillation is stopped as shown in FIG. 8.
- the wave-form E is for a voltage of an out-put of the oscillation control circuit 13a at a point E in FIG. 6.
- Pulse train is issued for the period of ⁇ 3 from the oscillating circuit of the PUT Q 4a and impressed on a switching transistor Q 7 , through a pulse transformer T 2a thereby giving the input signal of the wave-form F shown in FIG. 8 for operation of the transistor Q 7 .
- a negative cycle circuitry comprises a power source rectifying circuit 12b, an oscillating circuit 14b, and an oscillation control circuit 13b, and these are same with the positive cycle circuitry comprising the power source rectifying circuit 12a, the oscillating circuit 14a, and the oscillation control circuit 13a except a connection to the power sources thereof which are opposite each other. Accordingly, detail explanation about the negative cycle circuit construction is omitted here.
- the voltage wave-form V S is transduced to a wave-form G of a out-put voltage of the power source rectifying circuit 12b as shown in FIG.
- the oscillating circuit l4b issues pulses H shown in FIG. 8. Then the pulses H impressed to a switching transistor Q 8 . As a result, the transistor Q 7 is “on” in positive half cycle of the power source V S , and the transistor Q 8 is “on” in negative half cycle of the power source V S .
- the power source voltage V S is allwave-rectified by a diode bridge circuit DB 3 and is smoothed by a smoothing capacitor C 6 , then impressed on the transistors Q 7 and Q 8 through a transformer T 3 .
- a pulse wave-form I shown in FIG. 8 having both polarity of pulses (reignition pulses) is issued from secondary winding of the transformer T 3 , and is given to the discharge tube 3 through a capacitor C 7 . Then the reignition pulses start an ignition and maintain a lighting.
- the capacitor C 7 cuts off a low frequency voltage component from the discharge tube 3 and prevents a magnetic saturation in the transformer T 3 .
- a period that the reignition pulse issued from the pulse generator 4 can be controlled by a integration time of the oscillation control circuit 13a by determining the time constant of the resistor R 17a and the capacitor C 4a , or the period can be controlled by a reference voltage of the comparator in the oscillation circuit 13a by determining the voltage by the ratio of the resistors R 21a and R 22a .
- An oscillation frequency at the oscillating circuit 14a can be controlled by, for instance, selecting the values of the resistor R 13a and the capacitor C 3a .
- a reignition pulse impressing angle ⁇ 3 should be selected as ⁇ 3 > ⁇ 1 with respect to the firing angle ⁇ 1 or the zero-current period in each cycle of the lamp current.
- Performance curves'of the high pressure discharge lamp apparatus of present invention at a starting trangent state are shown in FIG. 9.
- characteristic of the lamp voltage is designated by the curve V La , the lamp current by I La , and firing angle at a condition that the starting lamp current is controlled during a period t from starting of lighting of the discharge tube by ⁇ .
- the transformer T 1 can be replaced by a suitable isolator for example, photo-isolator.
- the pulse generator 4 of FIG. 6 can be constituted by a digital IC, thereby a similar function is obtainable.
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Abstract
- the triack (TC) being controlled of its firing angle responding to an output of a current detection circuit (9) which detects a change of the lamp current through a change of the lamp voltage, and
- a pulse generator (4) is further connected in parallel to the discharge tube (3) and gives reignition pulse thereto at least during the zero-current period in each cycle of the lamp current.
Description
- This invention relates to an improvement in a high pressure discharge lamp apparatus such as a high pressure mercury lamp apparatus, a high pressure sodium lanp apparatus, or a high pressure metal-halide lamp apparatus. The present invention especially concerns an improvement in a high pressure discharge lamp apparatus of the type comprising a high pressure discharge tube, a current limiting device, for instance a choke coil, and a pulse generator output terminals of which are connected in parallel to the electrodes of the discharge tube for lighting the tube with a lamp voltage nearly equal to a power source voltage.
- Generally, in a conventional high pressure discharge lamp. apparatus, a current limiting device such as a choke coil and a discharge tube are connected in series across a power source.
- In the abovementioned type of the high pressure discharge lamp apparatus, a voltage of the power source should be maintained over 1.5 times a voltage of the discharge tube for preventing an extinction of ignition in the tube. Therefore a voltage drop across the current limiting device is high, and a power loss at the current limiting device is rather large. Accordingly, a dimension and a weight of the current limiting device become undesirably large.
- For improving the high pressure discharge lamp apparatus to eliminate the abovementioned defects, a pulse generator may be provided in a manner to give pulses to the discharge tube. By such impression of pulses across the discharge tube, the lamp voltage can be selected so high as nearly equal to the power source voltage.
- The conventional discharge lamp apparatus having a pulse generator as above-mentioned still has the following problems: (1) In a case that the high pressure discharge lamp is ignited in every cycle of the power source voltage by impressing of pulse by the pulse generator, a lamp voltage can be selected so high as nearly equal to the power source voltage, and an impedance of the current limiting device can be selected small. But, when the discharge tube starts to ignite, a lamp current grows excessively large, and therefore the impedance of the discharge tube such as the choke coil becomes almost zero for a magnetic saturation due to the overcurrent. Therefore, for avoiding the magnetic saturation, the choke coil as the current limiting device should be designed so as to have relatively large sectional area of a core thereof, thereby making the current limiting device large in dimension and expensive in cost.
- (2) In order to solve the abovementioned problem, another conventional high pressure discharge lamp apparatus has been devised as shown in FIG. 1, whrerin a current
limiting device 2 such as a choke coil, an auxiliary current limiting device 5 and a discharge tube 3 are connected in series across apower source 1. The auxiliary current limiting-device 5 of a relatively large size has more large capacity of current limitation than that of the currentlimiting device 2. And asemiconductor switching device 6 is connected in parallel to the auxiliary current limiting device 5. Apulse generator 4 is connected in parallel to the discharge tube 3 for supplying reignition pulses to the discharge tube 3. - In the abovementioned high pressure discharge lamp. apparatus, a duty time of the current limiting device 5 is controlled by firing angle controlling action of the
semiconductor switching device 6 in such manner that at the stating the duty time of theswitching device 6 is very small and at the steady lighting state the duty time is very large, so that effectively the auxiliary current limiting device 5 is substantially shot-circuited by theswitching device 6 at a steady lighting state of the lamp. Therefore a lamp current may be maintained for the same degree between at a steady lighting state and at a starting trangent state. - Generally, in the high pressure discharge tube an ignition of the discharge tube extincts every period when the lamp current is zero. Accordingly, if a series insertion of a thyristor to the high pressure discharge lamp of conventional type for attempting to limit the lamp current by changing its firing angle, the tube does not work due to zero current period in every cycle. Therefore, in the lamp apparatus of FIG. 1, lanp current is always supplied from the
power source 1 through the auxiliary current limiting device 5, which is connected in parallel to the thyristor or the like currentlimiting device 6, thereby to allow the current to flow without zero period made by thethyristor 6. However the problem of the conventional lamp apparatus is that though the currentlimiting device 2 can be designed relatively small, a large auxiliary current limiting. device 5 has been necessary. Accordingly the lamp apparatus can not be made in small size. - The pourpose of the invention is to provide a high pressure discahrge lanp apparatus having a pulse generator to impress pulses across the discharge tube for allowing selecting a lamp voltage very close to a power source voltage, and having no auxiliary current limiting device like the device 5 of the conventional high pressure discharge lamp apparatus shown in FIG. 1.
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- FIG. 1 is a block diagram of a conventional high pressure discharge lamp apparatus.
- FIG. 2 is a block diagram of a fundamental apparatus embodying the present invention.
- FIG. 3 is a block diagram of the actual apparatus embodying the present invention.
- FIG. 4 is a graph showing characteristic curves of a high pressure discharge tube at a starting transient state.
- FIG. 5 is a detailed circuit diagram of the apparatus of the present invention shown in FIG. 3.
- FIG. 6 is a detailed circuit diagram of a pulse generator shown in FIG. 5.
- FIG. 7A and FIG. 7B are wave-form chart showing wave-forms at various parts of the circuit shown in FIG. 5.
- FIG. 8 is a wave-form chart showing wave-forms at various parts of the circuit shown in FIG. 6.
- FIG. 9 is a graph showing performance curves of a high pressure discharge lamp apparatus of present invention at a starting trangent state.
- The high pressure discharge lamp apparatus of the present invention comprises a discharge tube and a current limiting device connected in series, an over-current protecting device is further connected in series to said discharge tube, over-current protecting device being controlled of its firing angle responding to an output of a current detection circuit, and a pulse generator is further connected in parallel to the discharge tube.
- A fundamental apparatus embodying the present invention is shown in FIG. 2.
- In FIG. 2, a current
limiting device 2 and an over-current protectingdevice 11 are connected in series with a discharge tube 3 across apower source 1. Apulse generator 4 is connected in parallel to the discharge tube 3 for supplying reignition pulses to the discharge tube 3. And a lamp current detecting circuit 9 for detecting a lamp current and giving control signal to the over- current protectingdevice 11 is connected in parallel to the discharge tube 3. Thepulse generator 4 is for preventing extinction of the tube and allowing a selection of a lamp voltage high enough close to a voltage of thepower source 1, by supplying the .reignition pulses to the discharge tube 3, during a period from near the zero-cross point of the voltage ofpower source 1 to a stated point for from the zero-cross point in every cycle of the voltage ofpower source 1. By means of the reignition pulses, extinction of the ignition in the discharge tube 3 may be effectively avoided even in the zero current period in each cycle of the lamp current. - FIG. 3 shows an apparatus embodying the present invention which uses a
semiconductor switching device 11 as the over-current protector and uses a lamp current detecting circuit 9, which in actual circuit is a voltage detection circuit which outputs a signal to indicate a voltage of the discharge tube 3 and has a specified relation with the lamp current, is shown in FIG. 3. In an embodiment of the present invention shown in FIG. 3, a current limiting device 2 (of passive element device such as a choke coil) and thesemiconductor switching device 11 as the over-current protector and a discharge tube 3 are connected in series across apower source 1. Apulse generator 4 for impressing reignition signal on the discharge tube 3 is connected in parallel to the latter. The lamp current detecting circuit 9 is connected in parallel to the discharge tube 3. And a firingangle controlling circuit 10 is disposed so as to receiving an out-put signal of the lamp current detecting circuit 9 and supply a firing angle controlling signal to theswitching device 11. A firing angle of theswitching device 11 is controlled based on a relation between the lamp current and the lamp voltage which is detected in the lamp current detecting circuit 9. And theswitching device 11 controls the firing angle, hence effective value of the current of the discharge tube 3 from thepower source 1, and thereby protects an over-current at the starting transient state. Thepulse generator 4 supplies reignition pulses in every cycles to the discharge tube 3 at least during the zero current period of the lamp current in order for avoiding an extinction of the discharge tube 3 due to zero current period both in starting transient state and steady lighting state. - Generally, in a high pressure discharge tube connected in series with choke coil or some impedance, for a starting transient state of the tube, a lamp voltage VLa and a lamp current ILa of the high pressure discharge tube show the curves as shown in FIG. 4. In FIG. 4, ZLa, which is relatively small at incipient period of starting of lighting in the discharge tube wherein a vapour pressure in the tube is relatively small. Then as time lapses the impedance ZLa increases. For that reason, the lamp current ILa, that is a current through the choke coil, decreases at the time lapses, and simultaneously the lamp voltage VLa increases as shown in FIG. 4. Accordingly, the amount of the lamp current ILa can be known by detecting the lamp voltage VLa based on abovementioned. relation between the current ILa and the voltage VLao Consequently, the lamp current ILa can be controlled by detecting the lamp voltage VLa primarily.
- The operation of the over-current protection in accordance with the high pressure discharge lamp apparatus of present invention is elucidated hereinafter referring to employing FIG. 5, FIG. 7A and FIG. 7B. FIG. 5 is a circuit diagram of the apparatus of the present invention. FIG. 7A and FIG. 7B are wave-form chart of various parts of the circuit shown in FIG. 5. In the chart of FIG. 5, a voltage across the discharge tube 3 is impressed to the lamp current detecting circuit 9 which detects a lamp current by detecting a lamp voltage. That is, in present invention, the lamp current is easily detected by a simple circuit as shown in FIG. 5. In the lamp current detecting circuit 9, the lamp voltage having a certain relation with the lamp current as shown in FIG. 4 is stepped down by a transformer Tl, and rectified by a diode bridge circuit DB2, and further smoothed by a circuit of resistor R1 and a capacitor C1. A voltage of the capacitor C1 is .divided by a circuit of resistors R2 and R3, and then impressed to the base of a transistor Q1 in a firing
angle controlling circuit 10. At immediately after a starting of lighting of the discharge tube 3, lamp voltage VLa is low as shown in FIG. 4. Therefore a voltage impressed to the base of the transistor Q1 is also in a low level, so that the transistor Ql maintains off state. On the other hand, a power source voltage having the wave-form VS shown in FIG. 7A is given to the firingangle controlling circuit 10, wherein the power source voltage VS is. led through a resistor R4, DB1 and R5, and then is level clipped by a regulate diode D1, whose voltage wave form V1 is shown in FIG. 7A. The voltage wave-form V1 is supplied to an anode of PUT (programmable unijunction transistor) Q2 through a resistor R6. At the immediately after a starting of lighting of the discharge tube 3, the transistor Q1 maintains off state as abovementioned, and hence the voltage of wave-form V1 is supplied to a capacitor C2 for charging only through the resistor R6. As a result of the charging, a voltage wave-form V2 of the capacitor C2 is formed as shown in FIG. 7A. As shown in FIG. 5, the voltage of wave-form V1 is divided by resistors Ra and R9, and the divided voltage is impressed to a gate of the PUT Q2. Hereupon, the voltage V2 of the capacitor C2 grows up and comes above the voltage impressed to the gate of the PUT Q2, hence the PUT Q2 turns on. Consequently the electric charge in the capacitor C2 discharges through the PUT Q2. As a result, a trigger pulse V3 as shown in FIG. 7A is produced across both ends of a resistor R10. A thyristor Th is triggered by the pulses V3 impressed through a resistor R11. When the thyristor Th turns on, both out-put ends of the diode brindge circuit DB1 are short-circuited by the thyristor Th, and hence the voltage V1 becomes zero, and then triggering action of the PUT Q2 is stopped. As abovementioned, the PUT Q2turns on at a firing angle corresponding to the time constant resistor R6 and the capacitor C2, and therefore, the thyristor Th turns on by receiving the triggering pulses V3 impressed to the gate thereof through the resistor R11. As a rectified source voltage is supplied to the thyristor Th through the diode bridge circuit DB1, the thyristor Th maintains "on" state until a forward current thereof becomes lower than a holding current of the thyristor Th at a timing near an end of every positive half cycle of the power source voltage VS. When the thyristor Th is in "on" state and the power source voltage VS is in the positive half cycle, a gate current flows in the triack TC as aswitching device 11 through the path of: power source 1 - current limiting device 2 - discharge tube 3 - gate of the triack TC - diode D2 - thyristor Th - diode bridge circuit DB1 -power source 1. And when the power source voltage VS is in the negative half cycle, the gate current of the triack TC flows through the path of: power source 1 - diode bridge circuit DB1 - thyristor Th ― diode D3 - gate of the triack TC discharge tube 3 current limiting device 2 -power source 1. In both cases of the positive half cycle and negative half cycle, the triack TC is "on" during the while the gate currents exist. Accordingly, a main load current ILa of the triack TC is appropriately controlled by the firingangle controlling circuit 10 which determines afiring angle 01 of the triack TC as shown in FIG. 7A. Although the main load current ILa has a zero current period in each cycle, by means of the reignition pulses VP are supplied to the discharge tube 3 at least during the zero current period in each cycle of the main load current ILa. - After lapse of some time period, the lamp voltage increases, and also the base potential of the transistor Q1 rises, so that the transistor Q1 turns on. When the transistor Q1 turns on, a series circuit of the resistor R7 and the internal resistance (collector-emitter resistance) of the on-state transistor Q1 is connected in parallel to the resistor R6, and therefore a charging time of the capacitor C2 is shortened. Accordingly a time till the PUT Q2 turns on is shortened, and therefore the time phase of trigger pulses V3 across the resistor R10 is led, hence the firing angle of the triack TC becomes very small as shown by θ2 (θ2<<θ1) in FIG. 7B. As a result, main load current of a wide firing angle flows through the triack TC as shown in FIG. 7B. As above- mentioned, an apparatus of present invention has a
pulse generator 4 and a switching device as an over-current protecting device, and the lamp current at the starting transient state is suppressed by over-current protecting device nearly equal to the lamp current at the steady lighting state, preventing the extinction by the reignition pulses from thepulse generator 4. - Therefore, the current limiting
device 2 can be designed small enough and further a loss therein can be satisfactorily diminished. - The
aforementioned pulse generator 4 is elucidated in detail in reference to FIG. 6 and FIG. 8. FIG. 6 is a detailed circuit diagram of thepulse generator 4, and FIG. 8 is a wave-form chart of various parts of the circuit shown in FIG. 6. When the power source voltage Vs is applied, thepulse generator 4 issues ignition pulses to the discharge tube 3, and the discharge tube 3 is ignited. Operation of thepulse generator 4 after starting of ignition is elucidated hereafter separating in two parts. First part is for the positive half cycle period of the power source voltage VS and the second part is for the negative half cycle period of the power source voltage V s. - In the positive half cycle period:
- In the positive half cycle of the power source voltage VS, the voltage Vs is rectified and level clipped by a power source rectifying circuit 12a consisting of a diode D4a, a resistor R12a, and a regulate diode D5a. An output voltage of the power source rectifying circuit 12a, that is a voltage of a point C in FIG. 6 is shown by a wave-form C of FIG. 8. A voltage of the wave-form C is supplied to an
oscilating circuit 14a and to an oscillation control circuit 13a. In the oscillation control circuit 13a, the voltage of the wave-form C is impressed to an integration circuit consisting of a resistor R17a and a capacitor C4a, then an integrated voltage of the capacitor C4a at a point D in FIG. 6 is impressed to the base of a transistor Q5a. A voltage wave-form D at the point D'is shown in FIG. 8. A comparator consisting of two transistors Q5a, Q6a, and three resistors R18a, R19a, R20a is formed in the oscillation control circuit 13a. A voltage of the point C is divided by resistors R21a and R22a and impressed to the base of the transistor Q6 in the comparator. DC component voltage of the collector of the transistor Q6a as an output of the comparator is cut off by a capacitor C5a, and the AC component is impressed on the base of a transistor Q3a in theoscillating circuit 14a through a diode D6a. In theoscillating circuit 14a, an oscillation frequency determined by a time constant of a resistor R13a and a capacitor C3a is maintained during the off state of the transistor Q3a. (A resistor R14a and a resistor R15a are adequately selected in a manner that a PUT Q4a maintains the oscillation.) When both ends of the capacitor C3a is short-circuited, an anode potential of the PUT Q4a changes to zero, and the oscillation stops. That is, in a duty time of a wave-form E, the oscillation is stopped as shown in FIG. 8. The wave-form E is for a voltage of an out-put of the oscillation control circuit 13a at a point E in FIG. 6. Pulse train is issued for the period of θ3 from the oscillating circuit of the PUT Q4a and impressed on a switching transistor Q7, through a pulse transformer T2a thereby giving the input signal of the wave-form F shown in FIG. 8 for operation of the transistor Q7. - In the negative half cycle period:
- In a negative half cycle of the power source voltage VS, the voltage Vs is rectified and level clipped by the power
source rectifying circuit 12b. A negative cycle circuitry comprises a powersource rectifying circuit 12b, anoscillating circuit 14b, and anoscillation control circuit 13b, and these are same with the positive cycle circuitry comprising the power source rectifying circuit 12a, theoscillating circuit 14a, and the oscillation control circuit 13a except a connection to the power sources thereof which are opposite each other. Accordingly, detail explanation about the negative cycle circuit construction is omitted here. In the negative half cycle of the power source voltage VS, the voltage wave-form VS is transduced to a wave-form G of a out-put voltage of the powersource rectifying circuit 12b as shown in FIG. 8. The oscillating circuit l4b issues pulses H shown in FIG. 8. Then the pulses H impressed to a switching transistor Q8. As a result, the transistor Q7 is "on" in positive half cycle of the power source VS, and the transistor Q8 is "on" in negative half cycle of the power source VS. - The power source voltage VS is allwave-rectified by a diode bridge circuit DB3 and is smoothed by a smoothing capacitor C6, then impressed on the transistors Q7 and Q8 through a transformer T3. A pulse wave-form I shown in FIG. 8 having both polarity of pulses (reignition pulses) is issued from secondary winding of the transformer T3, and is given to the discharge tube 3 through a capacitor C7. Then the reignition pulses start an ignition and maintain a lighting. The capacitor C7 cuts off a low frequency voltage component from the discharge tube 3 and prevents a magnetic saturation in the transformer T3. A period that the reignition pulse issued from the
pulse generator 4 can be controlled by a integration time of the oscillation control circuit 13a by determining the time constant of the resistor R17a and the capacitor C4a, or the period can be controlled by a reference voltage of the comparator in the oscillation circuit 13a by determining the voltage by the ratio of the resistors R21a and R22a. An oscillation frequency at theoscillating circuit 14a can be controlled by, for instance, selecting the values of the resistor R13a and the capacitor C3a. A reignition pulse impressing angle θ3 should be selected as θ3 > θ1 with respect to the firing angle θ1 or the zero-current period in each cycle of the lamp current. - Performance curves'of the high pressure discharge lamp apparatus of present invention at a starting trangent state are shown in FIG. 9. In FIG. 9, characteristic of the lamp voltage is designated by the curve VLa , the lamp current by ILa , and firing angle at a condition that the starting lamp current is controlled during a period t from starting of lighting of the discharge tube by θ.
- The transformer T1 can be replaced by a suitable isolator for example, photo-isolator. The
pulse generator 4 of FIG. 6 can be constituted by a digital IC, thereby a similar function is obtainable.
Claims (9)
characterized in,
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19810103046 EP0063168B1 (en) | 1981-04-22 | 1981-04-22 | High pressure discharge lamp apparatus |
DE8181103046T DE3175621D1 (en) | 1981-04-22 | 1981-04-22 | High pressure discharge lamp apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19810103046 EP0063168B1 (en) | 1981-04-22 | 1981-04-22 | High pressure discharge lamp apparatus |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0063168A1 true EP0063168A1 (en) | 1982-10-27 |
EP0063168B1 EP0063168B1 (en) | 1986-11-12 |
Family
ID=8187669
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19810103046 Expired EP0063168B1 (en) | 1981-04-22 | 1981-04-22 | High pressure discharge lamp apparatus |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0063168B1 (en) |
DE (1) | DE3175621D1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0246788A2 (en) * | 1986-05-13 | 1987-11-25 | British Aerospace Public Limited Company | Pulse generating circuits |
WO1992022182A1 (en) * | 1991-06-01 | 1992-12-10 | Robert Bosch Gmbh | Device for operating a gas discharge lamp |
GB2361818A (en) * | 2000-02-16 | 2001-10-31 | David William Ford | Discharge lamp phase control dimmer with current feedback |
CN103037602A (en) * | 2011-10-08 | 2013-04-10 | 张玉清 | Electronic ballast with adjustable luminance |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1150758B (en) * | 1961-02-02 | 1963-06-27 | Siemens Ag | Circuit arrangement for lighting high-pressure, high-power gas discharge lamps, in particular high-pressure long-arc lamps, as well as lighting system with this circuit arrangement |
US4048543A (en) * | 1976-10-04 | 1977-09-13 | General Electric Company | Discharge lamp operating circuit |
US4101809A (en) * | 1977-05-26 | 1978-07-18 | General Electric Company | Discharge lamp operating circuit |
-
1981
- 1981-04-22 DE DE8181103046T patent/DE3175621D1/en not_active Expired
- 1981-04-22 EP EP19810103046 patent/EP0063168B1/en not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1150758B (en) * | 1961-02-02 | 1963-06-27 | Siemens Ag | Circuit arrangement for lighting high-pressure, high-power gas discharge lamps, in particular high-pressure long-arc lamps, as well as lighting system with this circuit arrangement |
US4048543A (en) * | 1976-10-04 | 1977-09-13 | General Electric Company | Discharge lamp operating circuit |
US4101809A (en) * | 1977-05-26 | 1978-07-18 | General Electric Company | Discharge lamp operating circuit |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0246788A2 (en) * | 1986-05-13 | 1987-11-25 | British Aerospace Public Limited Company | Pulse generating circuits |
EP0246788A3 (en) * | 1986-05-13 | 1989-07-19 | British Aerospace Public Limited Company | Pulse generating circuits |
WO1992022182A1 (en) * | 1991-06-01 | 1992-12-10 | Robert Bosch Gmbh | Device for operating a gas discharge lamp |
GB2361818A (en) * | 2000-02-16 | 2001-10-31 | David William Ford | Discharge lamp phase control dimmer with current feedback |
CN103037602A (en) * | 2011-10-08 | 2013-04-10 | 张玉清 | Electronic ballast with adjustable luminance |
Also Published As
Publication number | Publication date |
---|---|
DE3175621D1 (en) | 1987-01-02 |
EP0063168B1 (en) | 1986-11-12 |
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