WO2007007951A1

WO2007007951A1 - Circuit for lighting flash lamp

Info

Publication number: WO2007007951A1
Application number: PCT/KR2006/001903
Authority: WO
Inventors: Hak Ki Choi
Original assignee: Max Engineering Ltd.
Priority date: 2005-07-13
Filing date: 2006-05-22
Publication date: 2007-01-18
Also published as: KR100554223B1

Abstract

A circuit for lighting a flash lamp is disclosed, which can maintain the operation of a high-voltage supply unit supplying a power supply voltage for lighting the flash lamp more stably, and reduce the size of the entire system through an integration of a supply unit of a low-voltage source onto the high-voltage supply unit. The circuit includes a high-frequency switching converter converting a drive power supply into a high-frequency AC power supply; a multi-transformer; a first and second trigger and simmer drive unit performing a trigger operation for performing an initial lighting of the flash lamp and a simmer operation for maintaining the flash lamp in a standby state; first and second safety extra low voltage (SELV) units supplying constant voltages for other parts of the laser generation system except for the flash light; a constant-voltage maintenance control unit removing an error; and a compulsory trigger stopping unit maintaining the simmer operation of the first and second trigger and simmer unit, and stopping the trigger operation thereof.

Description

CIRCUIT FOR LIGHTING FLASH LAMP

Technical Field

[1] The present invention relates to a circuit for lighting a flash lamp in a laser generation system, and more particularly to a circuit for lighting a flash lamp that can maintain the operation of a high- voltage supply unit supplying a power supply voltage for lighting the flash lamp more stably, and reduce the size of the entire system through an integration of a supply unit of a low- voltage source for a system drive that controls the operation of the laser generation system onto the high- voltage supply unit. Background Art

[2] Generally, laser is commonly called light (i.e., electromagnetic wave) generated using an inductive radiation property of an atomic material that is in an excited state. The basic construction for generating laser is illustrated in FlG. 1, and the principle of laser generation will now be explained.

[3] Population inversion (which means a state that the number of atomic populations on a high energy level is larger than that on a low energy level, and which is also called a negative temperature state) is formed between two proper energy levels of an atomic group (or material). In this case, by an incident light, atoms on a high energy level are transited to a low energy level to give energy to the light, which is called a stimulated emission of radiation. As a result, the incident light is strengthened with its frequency and phase maintained.

[4] This is called an amplification of interference phosphorescence. By making an amplified light repeat going and returning on a negative temperature medium put in an optical resonator, a self-excited oscillation of light occurs to produce laser. Accordingly, the laser light becomes waves having coincident phases, and thus its property is essentially different from that of an ordinary light. The optical resonator has a basic structure in which two plane mirrors having a high reflection rate are arranged in parallel with each other, and steady-state waves that are perpendicular to the plane present a resonance mode.

[5] Since a large number of optical resonance modes exist in a frequency range that can be amplified as a laser medium, it is common that lasers simultaneously oscillate in several modes. Laser that oscillates in a single mode is called a single frequency laser. Also, a continuous wave laser having continuously oscillating light and a pulse laser exist.

[6] A method that has been widely used to generate laser light is a method for oscillating laser light by exciting photons through an irradiation of a strong flash onto a bar-shaped light source medium. In this case, in order to generate a flashlight by lighting a xenon or crypton lamp that is used as a flash lamp, high-level charges are charged in an energy charging capacitor, and then the charges charged in the capacitor are discharged to the flash lamp.

[7] In addition, in order to perform an initial lighting of the above-described flash lamp, it is required to excite discharged gas in a tube to a plasma state by applying a high voltage of about 10,000 to 20,000 volts between an anode and a cathode of the flash light. The ionized gas in the tube abruptly forms a path for discharging the high voltage to achieve a lighting state, and this initial lighting state is called a trigger. If the turning-on/off of the flash lamp is repeated rapidly, it is not desirable for the lifetime of the lamp to apply flash pulses to the lamp as the high- voltage triggers. In this case, a method for applying a high- voltage trigger pulse to the lamp only at an initial lighting stage of the lamp and then making a minimum DC current flow through the lamp, in order to maintain the once-lighted lamp continuously in its lighting state, has been generally used.

[8] The minimum maintenance DC current as described above is called a simmer current.

[9] Accordingly, when a voltage having a great energy is applied between the anode and the cathode of the flash lamp, which has been once triggered and is in a simmer state, from a capacitor for charging energy, an energy discharge is made, and a strong flashlight is generated.

[10] The simmer voltage is a DC voltage of about several hundred volts, and the voltage charged in the energy discharge capacitor is higher than the simmer voltage, and in the range of several hundred to two thousand volts.

[11] A conventional device for performing the above-described trigger and simmer functions, as shown in FlG. 2, includes several individual assembled parts, and this causes the scale of the apparatus to be large with the manufacturing cost heightened.

[12] Referring to FlG. 2, the conventional device is provided with two trigger and simmer circuit units 1OA and 1OB having the same construction and the same function. This is because the optical structure for generating laser light requires two stages: an oscillation unit OSC and an amplification unit AMP.

[13] The conventional device is also provided with two safety extra low voltage (SELV) units 2OA and 2OB having the same construction and the same function. This is because several kinds of insulated low-level DC voltages (e.g., +5 V, +12V, and -12V) are required to drive various kinds of control system circuits and cooling fan motors of the entire device.

[14] The first trigger and simmer circuit unit 1OA operates as follows.

[15] A commercial AC supply voltage inputted through a key switch SWl is rectified and smoothed through a unit A, and a DC voltage outputted from the unit A is converted into a high-frequency AC voltage by a high-frequency (e.g., about 50KHz) switching operation of a DC-to-AC converter B. the high-frequency AC voltage outputted from the converter B is transferred to a primary coil of a transformer Tl.

[16] An AC voltage induced in a secondary coil is rectified by a diode Dl and a capacitor Cl to be outputted as a sub-high voltage, and is rectified by a diode D2 and a capacitor C2 to be outputted as a simmer voltage.

[17] The sub-high voltage has an initial voltage value of about 3 to 4 KV, and is charged in a high- voltage capacitor C5 through a series path composed of first to third resistors Rl to R3, as a positive (+) voltage.

[18] The simmer voltage (in the range of 100 to 300V) generated between both end terminals of the capacitor C2 is charged in a capacitor C4 through a resistor R4, and is also charged in a capacitor C3 after being divided through resistors R5 and R6. If this voltage reaches a trigger voltage value of a diac 1, an SCR 1 is turned on, and the voltage charged in the capacitor C4 is applied to a primary coil of a high- voltage step- up transformer T2.

[19] As a result, in a secondary coil of the high- voltage transformer T2, a high- voltage pulse in the range of about 5 to 15 KV is induced, and this high- voltage pulse is added to the sub-high voltage having been charged in the capacitor C5, and the added voltage is supplied to an anode of a lamp OSC to trigger the lamp.

[20] The lamp triggered as above is kept in a standby state by the simmer voltage coming through the diode D3.

[21] Accordingly, simmer current flows to a relay RLYl immediately when the lamp is maintained in the simmer state, and the relay is turned on to output a "SIMMER-OK" signal. This signal is sent to a microcomputer circuit that controls the entire system, and is used to manage an operation sequence of the system.

[22] The operation of the second trigger and simmer circuit unit 1OB is the same as that of the first trigger and simmer circuit unit 1OA. The second trigger and simmer circuit maintains another lamp in the simmer state.

[23] If a second switch SW2 and a third switch SW3, which are connected to the respective lamps being kept in the simmer state, are turned on, charges having been charged in a sixth capacitor C6 and a seventh capacitor C7 are discharged through the respective lamps to make the lamps generate flashlight.

[24] On the other hand, although the SELV units 2OA and 2OB are illustrated in the same drawing, they are universal switch mode power supply (SMPS) devices having separate units from each other, and output stable DC low voltages (of which the output voltage values may be changed as needed) that are insulated from the commercial AC power supply line. [25] However, the conventional device has the following problems:

[26] First, in the conventional device, four separate modules are used, and this increases the complexity of the device.

[27] Second, since the sub-high voltage generated in the capacitor Cl is continuously being outputted even while the lamps are in the simmer state, the resistors Rl to R3, which have served as sub-high voltage conductors in order to generate a trigger voltage at an initial stage, act as loads after the lamps achieve the simmer state, and this causes a power loss to occur. In order to suppress this, resistors having a large allowable power loss should be used as the corresponding resistors Rl to R3, and this causes the scale of the device to be increased.

[28] Third, in order to obtain the sub-high voltage, the number of secondary windings of the transformer Tl should be increased, and this may cause trouble to occur frequently due to the dielectric breakdown among the windings.

[29] Fourth, since the SCR is turned on due to the continuous self-oscillation of the diac even after the lamps achieve the simmer state, the trigger pulse is continually generated from the secondary coil of the high- voltage transformer T2, and this causes the dielectric strength among windings to be weakened.

[30] Last, when a hit of the commercial AC poser supply voltage occurs, the system is reset, and this may cause safety accident to occur in the case where the device is applied to medical equipment. Disclosure of Invention Technical Problem

[31] Therefore, the present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a circuit for lighting a flash lamp in a laser generation system that can maintain the operation of a high- voltage supply unit supplying a power supply voltage for lighting the flash lamp more stably, and reduce the size of the entire system by employing a single off-line converter (which is a device that generates DC or pulse voltages insulated from a commercial AC line) that can simultaneously perform the functions of the above- described trigger and simmer circuit units and SELV units.

[32] It is another object of the present invention to provide a circuit for lighting a flash lamp in a laser generation system that can prevent an unnecessary power loss and a high-level trigger voltage from being generated after the lamp achieves a simmer state, and stop the operation of the system if a trigger of the lamp does not succeed within a predetermined time after an initial trigger fails due to a hit of the commercial AC power supply or aging of the lamp. Technical Solution [33] In order to achieve the above object, in one aspect of the present invention, there is provided a circuit for lighting a flash lamp in a laser generation system that generates laser light by exciting photons of a bar-shaped light source medium by discharging high-level charges charged in an energy charging capacitor to the flash lamp and thus making the flash lamp irradiate a strong flashlight onto the bar-shaped light source medium, which includes a high-frequency switching converter receiving and converting a drive power supply obtained by rectifying a commercial AC power supply into a high-frequency AC power supply, and varying a frequency of the output high- frequency AC power supply according to an input control signal; a multi-transformer receiving the AC power supply outputted from the high-frequency switching converter through its primary coil, and inducing AC power supplies in its secondary coils; a first and second trigger and simmer drive unit receiving the power supplies induced in the secondary coils of the multi-transformer, performing a trigger operation for performing an initial lighting of the flash lamp according to an on-operation control signal, and performing a simmer operation for maintaining the flash lamp in a standby state so that the flash lamp can generate the flashlight by a discharge voltage of the energy charging capacitor; first and second safety extra low voltage (SELV) units receiving the power supply induced in the secondary coils of the multi-transformer and supplying constant voltages having specified voltage levels as drive power supplies of other parts of the laser generation system except for the flash light; a constant- voltage maintenance control unit receiving any one of the constant voltages outputted from the first and second SELV units, recognizing an error of an output state by comparing the received constant voltage with a predetermined reference voltage, and removing the error by controlling the operation of the high-frequency switching converter based on the recognized error; and a compulsory trigger stopping unit sensing signals according to a simmer operation state of the first and second trigger and simmer drive unit, maintaining the simmer operation of the first and second trigger and simmer unit, and stopping the trigger operation of the first and second trigger and simmer drive unit.

[34] The circuit for lighting a flash light according to the present invention may further include a flash lamp lighting control unit controlling the operation of the first and second trigger and simmer drive unit by performing a logical operation of the signals sensed by the compulsory trigger stopping unit according to the simmer operation state of the first and second trigger and simmer drive unit, a sensed signal of a supply state of the commercial AC power supply, and a user request signal.

[35] The first and second trigger and simmer circuit may include LC resonance units receiving the power supplies during an on-operation of relays that switches the power supplies induced in the secondary coils of the multi-transformer according to the control signal, and generating series resonance frequencies that are Q times higher than the frequencies of the input power supplies, respectively; high-frequency rectifying units rectifying the high-frequency power supplies outputted from the LC resonance units, respectively; simmer current sensing units receiving the rectified power supplies outputted from the high-frequency rectifying units, and sensing simmer currents from the received power supplies; and trigger pulse generation units receiving the rectified power supplies outputted from the high-frequency rectifying units, and generating trigger pulses, respectively.

[36] The compulsory trigger stopping unit may include a first AND gate receiving and

AND-gating signals outputted from the simmer current sensing units; and a trigger pulse stop signal generation unit receiving an output signal of the first AND gate, and if a predetermined logic value is outputted, preventing the trigger pulse generation units from generating the trigger pulses.

[37] The constant-voltage maintenance control unit may include an output voltage error detection unit receiving any one of the voltages outputted from the first and second SELV units, and detecting a degree of the error by comparing the received voltage with the predetermined reference voltage; and an excitation frequency control unit changing the level of the voltage applied to the primary coil of the multi-transformer by changing the frequency of the high-frequency switching converter according to the degree of the error outputted from the output voltage error detection unit.

[38] The flash lamp lighting control unit may include a system operation mode switch controlling the operation state of the system by three modes in an on-operation state of a power switch that inputs the commercial AC power supply to the system; a power on/off sensing unit sensing whether the system power supply has been inputted by sensing the power output according to the operation of the power switch and the system operation mode switch; an inverter receiving and inverting the signal sensed by the compulsory trigger stopping unit according to the simmer operation state of the first and second trigger and simmer drive unit; a third AND gate receiving and AND- gating an output signal of the power on/off sensing unit and a mode selection signal of the system operation mode switch; a relay drive unit receiving an output signal of the third AND gate, and if the predetermined logic value is outputted, turning on the relays; a timer circuit receiving and counting an output signal of the relay drive unit for a predetermined time, and reporting the result of counting if the predetermined time elapses; a second AND gate receiving and AND-gating the report signal of the timer circuit and an output signal of the inverter; and a relay drive-off signal generation unit receiving an output signal of the second AND gate, and if the predetermined logical value is outputted, compulsorily stopping the operation of the relay drive unit. Advantageous Effects [39] The circuit for lighting a flash lamp as constructed above according to the present invention can maintain the operation of a high- voltage supply unit supplying a power supply voltage for lighting the flash lamp more stably, and can reduce the size of the entire system through an integration of a supply unit of a low-voltage source for a system drive that controls the operation of the laser generation system onto the high- voltage supply unit. Brief Description of the Drawings

[40] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[41] FlG. 1 is an exemplary view explaining the general principle of laser generation;

[42] FlG. 2 is a circuit diagram illustrating the construction of a conventional circuit for lighting a flash lamp;

[43] FlG. 3 is a block diagram illustrating the construction of a circuit for lighting a flash lamp according to the present invention;

[44] FlGs. 4 and 5 are block diagrams illustrating the construction of examples of the flash lamp lighting circuit of FlG. 3; and

[45] FlGs. 6a to 6e are waveform diagrams illustrating waveforms appearing at various points of the circuit according to the present invention. Best Mode for Carrying Out the Invention

[46] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and thus the present invention is not limited thereto.

[47] FlG. 3 is a block diagram illustrating the construction of a circuit for lighting a flash lamp according to the present invention.

[48] Referring to FlG. 3, the circuit for lighting a flash lamp according to the present invention includes a power switch SW4 for inputting a commercial AC power supply to a system, a system operation mode switch s controlling the operation state of the system by three modes in an on-operation state of the power switch SW4, a power on/ off sensing unit q sensing whether the system power supply has been inputted by sensing the power output according to the operation of the power switch SW4 and the system operation mode switch s, a rectifying and smoothing unit a rectifying and smoothing the commercial AC power supply and outputting a DC power supply when the system operation state is maintained by the system operation mode switch s in the on-operation state of the power switch SW4, and a high-frequency switching converter b converting the DC power supply outputted from the rectifying and smoothing unit a into a high-frequency AC power supply according to a frequency control signal and applying the high-frequency AC power supply to a primary coil Wl of a multi- transformer T7.

[49] The circuit for lighting a flash lamp according to the present invention also includes a first LC resonance unit c receiving the power supply induced in a secondary first coil W2 of the multi-transformer T7 during an on-operation of a third relay RL Y3 that switches the power supply according to the control signal and generating a series resonance frequency that is Q times higher than the frequency of the input power supply, a first high-frequency rectifying unit e rectifying the high-frequency power supply outputted from the first LC resonance unit c, a first simmer current sensing unit g receiving the rectified power supply outputted from the first high-frequency rectifying unit e and sensing a simmer current from the received power supply, a first trigger pulse generation unit h receiving the rectified power supply outputted from the first high-frequency rectifying unit e and generating a trigger pulse, a second LC resonance unit d receiving the power supply induced in a secondary second coil W3 of the multi-transformer T7 during an on-operation of a fourth relay RL Y4 that switches the power supply according to the control signal and generating a series resonance frequency that is Q times higher than the frequency of the input power supply, a second high-frequency rectifying unit f rectifying the high-frequency power supply outputted from the second LC resonance unit d, a second simmer current sensing unit i receiving the rectified power supply outputted from the second high-frequency rectifying unit f and sensing a simmer current from the received power supply, and a second trigger pulse generation unit j receiving the rectified power supply outputted from the second high-frequency rectifying unit f and generating a trigger pulse.

[50] The circuit for lighting a flash lamp according to the present invention also includes a first AND gate ANDl receiving and AND-gating signals outputted from the first and second simmer current sensing units g and i, a trigger pulse stop signal generation unit k receiving an output signal of the first AND gate ANDl, and if a predetermined logic value (e.g., logic "1") is outputted, preventing the second trigger pulse generation unit j from generating the trigger pulse, a third high-frequency rectifying unit w rectifying the power supply induced in a secondary third coil W4 of the multi-transformer T7, a first SELV unit 2OA generating and outputting a stable DC low-voltage using the power supply rectified by the third high-frequency rectifying unit w, a fourth high- frequency rectifying unit x rectifying the power supply induced in a secondary fourth coil W5 of the multi-transformer T7, a second SELV unit 2OB generating and outputting a stable DC low- voltage using the power supply rectified by the fourth high- frequency rectifying unit x, an output voltage error detection unit o receiving the output voltage of the second SELV unit 2OB and detecting a degree of an error by comparing the received voltage with the predetermined reference voltage, and an excitation frequency control unit n changing the level of the voltage applied to the primary coil Wl of the multi-transformer T7 by changing the frequency of the high- frequency switching converter b according to the degree of the error outputted from the output voltage error detection unit.

[51] The circuit for lighting a flash lamp according to the present invention also includes an inverter INT receiving and inverting the output signal of the first AND gate ANDl, a third AND gate AND3 receiving and AND-gating an output signal of the power on/ off sensing unit q and a mode selection signal of the system operation mode switch s, a relay drive unit p receiving an output signal of the third AND gate AND3, and if the predetermined logic value (e.g., logic "1") is outputted, turning on the third and fourth relays RL Y3 and RL Y4, a timer circuit I receiving and counting an output signal of the relay drive unit p for a predetermined time, and reporting the result of counting if the predetermined time elapses; a second AND gate AND2 receiving and AND-gating the report signal of the timer circuit I and an output signal of the inverter INT, and a relay drive-off signal generation unit m receiving an output signal of the second AND gate AND2, and if the predetermined logical value (e.g., logic "1") is outputted, com- pulsorily stopping the operation of the relay drive unit p.

[52] The detailed constructions of the circuit for lighting a flash lamp as constructed above according to the present invention are illustrated in FIGs. 4 and 5.

[53] The constructions of the circuit according to the present invention are merely exemplary, and the present invention is not limited thereto.

[54] FIGs. 6a to 6e are waveform diagrams illustrating waveforms appearing at various points of the circuit according to the present invention.

[55] The operation of the flash lamp lighting circuit in a laser generation system according to the present invention will be explained with reference to FIGs. 3, 4, 5, and 6a to 6e.

[56] The input of the commercial AC power supply is controlled by the main power switch SW4. If the main power switch SW4 is in an on state, the DC voltage produced in the rectifying and smoothing circuit a is inputted to the high-frequency switching converter b.

[57] The high-frequency switching converter b has a basic construction of a frequency modulation type series resonance half-bridge that performs a high-frequency switching operation in the frequency range of about 40 KHz to 80 MHz.

[58] The high-frequency AC voltage, which is obtained by the switching operation of the high-frequency switching converter b and which has a waveform as illustrated in FIG. 6a, is inputted to the primary winding Wl of the multi-transformer T7, and voltages induced in the secondary windings W4 and W5 of the multi-transformer T7 are rectified by the third and fourth high-frequency rectifying units w and x to be supplied to the first SELV unit 2OA and the second SELV unit 2OB as stable DC low- voltages.

[59] Meanwhile, voltages induced in the secondary windings W2 and W3 of the multi- transformer T7 for supplying a simmer current and a trigger pulse to the flash light are controlled by the relays RLY3 and RL Y4, which are turned on according to the user's request only and through which the power supply is applied to the flash lamp.

[60] The LC resonance units c and d that follow the relays RL Y3 and RL Y4 have their resonance points in the high-frequency switching frequency or in a frequency that is a multiple of the high-frequency switching frequency, and the voltages in the secondary windings W2 and W3 of the multi-transformer T7 are changed to high-frequency voltages Q times as high as the voltages in the secondary windings W2 and W3 by the high-frequency AC voltage generated by the switching operation of the high-frequency switching converter b.

[61] In this case, if one output voltage of the SELV unit becomes higher than the reference voltage, the output voltage error detection unit o controls the excitation frequency control unit n to output a higher excitation frequency, while otherwise, it controls the excitation frequency control unit n to output a lower excitation frequency. The excitation frequency is applied to the high-frequency switching converter b to control the high-frequency AC voltage being supplied to the primary coil Wl of the high-frequency switching converter b, resulting in that the secondary output voltage thereof is kept constant.

[62] If the main power switch SW4 is turned on, constant output voltages are supplied to the SELV units 2OA and 2OB, and thus a microcomputer (not illustrated) for a system control may be kept in a standby state.

[63] Also, the output voltages induced in the secondary windings W2 and W3 of the multi-transformer T7 are set to about 300 to 600V according to the characteristics of flash lamps, and these voltages are intercepted until the respective relays RL Y3 and RL Y4 are turned on.

[64] In order to achieve the trigger and simmer state, a power-on sensing signal and a

12V voltage signal inputted through switches SW5 and SW6 constituting the three- stage system operation mode switch s are AND-gated by a photo coupler PC 13, and an output signal of the photo coupler PC 13 turns on an SCR of a relay drive unit p to cause the relays RL Y3 and RL Y4 to be turned on.

[65] The three-stage switch sis a three-mode switch composed of the switches S5 and S6 each having "0", "1", and "2" contact terminals. If the switches SW5 and SW6 are switched over to the "0" terminals, respectively, the entire system is in an off state, while if the switches SW5 and SW6 are switched over to the "1" terminals, re- spectively, the commercial AC power supply is inputted through the on-state switch SW5 and the switch SW6 is in an off state.

[66] If the switches SW5 and SW6 are switched over to the "2" terminals, respectively, they are not fixed to the "2" terminals, but are returned to the "1" terminals. Accordingly, the switch SW5 is kept in an on state to continuously provide the commercial AC power supply through the switch SW5, and the switch SW6 is instantaneously turned on to provide an instantaneous 12V voltage through the switch SW6.

[67] At the moment the switch s which was switched over to the "2" terminal returns to the "1" terminal, the output signal of the third AND gate AND3 is kept in a logic "1" state, and thus a 12V voltage is applied to the relay drive unit p. Accordingly, the SCR in the relay drive unit is turned on to continuously maintain the corresponding state.

[68] As the relay drive unit p is turned on, the third and fourth relays RL Y3 and RL Y4 are also turned on, and thus the first and second LC resonance units c and d operate.

[69] In this case, the first and second LC resonance units c and d have their resonance points in the high-frequency switching frequency or in a frequency that is a multiple of the high-frequency switching frequency, and the voltages in the secondary windings W2 and W3 of the multi-transformer T7 are changed to high-frequency voltages Q times as high as the voltages in the secondary windings W2 and W3 by the high- frequency AC voltage generated by the switching operation of the high-frequency switching converter b.

[70] In this case, the relation between the sub-high voltage and the simmer voltage according to the on-operation of the system operation mode switch s is illustrated in FlG. 6b. When the system operation mode switch sis turned on, the voltage is increased and maintained up to 1200V until a trigger time point arrives, and the simmer voltage of about 300V is maintained at the trigger time point.

[71] In the initial drive state, the trigger operation is actually performed in a manner that the output voltages of the simmer current sensing units g and i for outputting voltages for maintaining the simmer state and the output signals of the trigger pulse generation units h and j are added together at cathodes of diodes D5 and D6 for preventing reverse current, respectively, and the added voltage signals are applied to flash lamps Lampl and Lamp2.

[72] In this case, the waveform of the voltage applied to anodes of SCRs SCRl 1 and

SCR12 of the trigger pulse generation units h and j is shown in FlG. 6c. This voltage is the same as the Zener voltage of the Zener diodes D25 and D26.

[73] The input voltage curve of diacs C20 and C21 according to the voltage applied to the anodes of the SCRs SCRIl and SCR12 is illustrated in HG. 6d.

[74] At the moment the trigger operation is performed, the photo couplers PCl 1 and

PC 12 serve as the first AND gate ANDl, and its output voltage is applied to the trigger pulse stop signal generation unit k, so that the operation of the trigger pulse generation units h and j are compulsorily stopped by the output signal of the trigger pulse stop signal generation unit k.

[75] Although the operation of the trigger pulse generation units h and j are compulsorily stopped by the operation of the trigger pulse stop signal generation unit k, the flash lamps have been sufficiently lighted through a specified delay time occurring according to the signal flow, and thereafter the flash lamps are maintained in a simmer operation state by the output voltages of the simmer current sensing units gand i.

[76] Even if the supply voltages are applied again after the supply voltages become reluctantly off in the process of maintaining the simmer operation state, the device does not achieve the operation state, but is kept in an off state. This is because the SCR 13 being once turned off simultaneously with the power-off is not turned on unless the switch s is manually switched over to the "2" terminal.

[77] In addition, in order to cope with the trigger and simmer unable situation due to the aging of the lamps and so on, the timer circuit I generates a time sensing signal in the range of 5 to 15 seconds (set value) after the relay drive signal is generated through the switchover of the mode selection switch s to the "2" terminals. In this case, a voltage set by a resistor R40 and a resistor R37 is charged in a capacitor C32 through a resistor R36, and this charging voltage is gradually increased in the above-described time. This charging voltage is compared with a gate voltage of an IC 1 through a resistor R39, and if the charging voltage is higher than the gate voltage of the IC 1, the IC 1 is turned on to generate the timer output.

[78] In addition, if the power supply becomes off, the capacitor C32 once charged is immediately discharged through a resistor R38, and thus the initial operation is repeated during the next power-on operation.

[79] The output of the timer I turns on a transistor Q5 through a resistor R41, and then turns on a transistor Q7 through a resistor R42, so that the operation of the relay drive unit p is stopped.

[80] Accordingly, if the predetermined time elapses after the switch s is turned on (i.e., switchover to "2" terminal), the relay drive signal output is turned off. However, if a SIMMER-OK is generated within a predetermined time, the relay drive signal output is not turned off, but is maintained.

[81] This is because if the "SIMMER-OK" signal is generated, current flows to the base of a transistor Q8 that serves as an inverter INT through a resistor R43, and thus the base level of the transistor Q7 becomes "0" so that a relay drive off signal is not generated. Industrial Applicability [82] As described above, according to the circuit for lighting a flash lamp according to the present invention, the operation of a high- voltage supply unit supplying a power supply voltage for lighting the flash lamp can be maintained more stably, and the size of the entire system can be reduced through an integration of a supply unit of a low- voltage source for a system drive that controls the operation of the laser generation system onto the high-voltage supply unit.

[83] While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment and the drawings, but, on the contrary, it is intended to cover various modifications and variations within the spirit and scope of the appended claims.

Claims

[1] A circuit for lighting a flash lamp in a laser generation system that generates laser light by exciting photons of a bar-shaped light source medium by discharging high-level charges charged in an energy charging capacitor to the flash lamp and thus making the flash lamp irradiate a strong flashlight onto the bar-shaped light source medium, the circuit comprising: a high-frequency switching converter receiving and converting a drive power supply obtained by rectifying a commercial AC power supply into a high- frequency AC power supply, and varying a frequency of the output high- frequency AC power supply according to an input control signal; a multi-transformer receiving the AC power supply outputted from the high- frequency switching converter through its primary coil, and inducing AC power supplies in its secondary coils; a first and second trigger and simmer drive unit receiving the power supplies induced in the secondary coils of the multi-transformer, performing a trigger operation for performing an initial lighting of the flash lamp according to an on- operation control signal, and performing a simmer operation for maintaining the flash lamp in a standby state so that the flash lamp can generate the flashlight by a discharge voltage of the energy charging capacitor; first and second safety extra low voltage (SELV) units receiving the power supply induced in the secondary coils of the multi-transformer and supplying constant voltages having specified voltage levels as drive power supplies of other parts of the laser generation system except for the flash light; a constant- voltage maintenance control unit receiving any one of the constant voltages outputted from the first and second SELV units, recognizing an error of an output state by comparing the received constant voltage with a predetermined reference voltage, and removing the error by controlling the operation of the high-frequency switching converter based on the recognized error; and a compulsory trigger stopping unit sensing signals according to a simmer operation state of the first and second trigger and simmer drive unit, maintaining the simmer operation of the first and second trigger and simmer unit, and stopping the trigger operation of the first and second trigger and simmer drive unit.

[2] The circuit of claim 1, further comprising a flash lamp lighting control unit controlling the operation of the first and second trigger and simmer drive unit by performing a logical operation of the signals sensed by the compulsory trigger stopping unit according to the simmer operation state of the first and second trigger and simmer drive unit, a sensed signal of a supply state of the commercial AC power supply, and a user request signal.

[3] The circuit of claim 1, wherein the first and second trigger and simmer circuit comprises:

LC resonance units receiving the power supplies during an on-operation of relays that switches the power supplies induced in the secondary coils of the multi- transformer according to the control signal, and generating series resonance frequencies that are Q times higher than the frequencies of the input power supplies, respectively; high-frequency rectifying units rectifying the high-frequency power supplies outputted from the LC resonance units, respectively; simmer current sensing units receiving the rectified power supplies outputted from the high-frequency rectifying units, and sensing simmer currents from the received power supplies; and trigger pulse generation units receiving the rectified power supplies outputted from the high-frequency rectifying units, and generating trigger pulses, respectively.

[4] The circuit of claim 1 or 3, wherein the compulsory trigger stopping unit comprises: a first AND gate receiving and AND-gating signals outputted from the simmer current sensing unit; and a trigger pulse stop signal generation unit receiving an output signal of the first AND gate, and if a predetermined logic value is outputted, preventing the trigger pulse generation units from generating the trigger pulses.

[5] The circuit of claim 1, wherein the constant- voltage maintenance control unit comprises: an output voltage error detection unit receiving any one of the voltages outputted from the first and second SELV units, and detecting a degree of the error by comparing the received voltage with the predetermined reference voltage; and an excitation frequency control unit changing the level of the voltage applied to the primary coil of the multi-transformer by changing the frequency of the high- frequency switching converter according to the degree of the error outputted from the output voltage error detection unit.

[6] The circuit of any one of claims 1 to 3, wherein the flash lamp lighting control unit comprises: a system operation mode switch controlling the operation state of the system by three modes in an on-operation state of a power switch that inputs the commercial AC power supply to the system; a power on/off sensing unit sensing whether the system power supply has been inputted by sensing the power output according to the operation of the power switch and the system operation mode switch; an inverter receiving and inverting the signal sensed by the compulsory trigger stopping unit according to the simmer operation state of the first and second trigger and simmer drive unit; a third AND gate receiving and AND-gating an output signal of the power on/off sensing unit and a mode selection signal of the system operation mode switch; a relay drive unit receiving an output signal of the third AND gate, and if the predetermined logic value is outputted, turning on the relays; a timer circuit receiving and counting an output signal of the relay drive unit for a predetermined time, and reporting the result of counting if the predetermined time elapses; a second AND gate receiving and AND-gating the report signal of the timer circuit and an output signal of the inverter; and a relay drive-off signal generation unit receiving an output signal of the second AND gate, and if the predetermined logical value is outputted, compulsorily stopping the operation of the relay drive unit.