JP2011151504A - Load drive controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable driving of a load drive controller with high luminance while suppressing power consumption, and to improve the lifetime of the entire drive control circuit. <P>SOLUTION: This load drive controller is provided with a drive control part 10 connected to a load 20. The drive control part 10 includes a constant current pulse driving part 14 which generates a first drive pulse P1 by a first on/off period obtained by specifying an on period of the load 20 by performing pulse width modulation on the basis of a rated current value IF of the load 20 and a peak current value Ip preset from an absolute maximum rated current value Imax when pulse-driven, and also generates a second drive pulse P2 by a second on/off period such that the maximum amplitude of a pulse is Ip by further performing switching during the on period of the first on/off period. The load 20 is continuously driven by applying current driven by the second drive pulse P2 to the load 20, and a ceramic capacitor having the lifetime of high reliability for a capacitance C1 of a charging and discharging control part 15 is used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a load drive control device for driving and controlling loads such as light emitting diodes (LEDs), motors, and actuators with a pulse signal having a constant period.

  In recent years, a lighting device using a light emitting diode (LED) as an example of a load is being widely used. For example, low power consumption and long life compared with conventional incandescent lamps, mercury lamps, metal halide lamps, etc. New demand, including alternative demand, is rapidly advancing due to performance such as low heat generation. The simplest method for adjusting the amount of light of such an LED is to adjust the value of the current flowing through the LED. However, the light emission characteristic of the LED has a problem that the visible color appears to change as the wavelength changes according to the amount of current flowing. In order to improve such a problem, a pulse width modulation (PWM) method is generally used for light amount adjustment control (Patent Documents 1 and 2).

  Patent Document 3 discloses an apparatus for preventing overcurrent at a low voltage by detecting a peak current in a light source load unit to which an LED is connected.

  FIG. 5 shows a basic circuit configuration of an LED lighting circuit using a conventional PWM method. This LED lighting circuit is configured to include a current limiting resistor R0, a semiconductor switch Q0, and a PWM control circuit. The current limiting resistor R0 is a resistor that limits the current flowing through the LED, and is connected in series to the LED. One of the series circuits is connected to the power supply line Vcc, and the other is connected to the ground (GND) via the semiconductor switch Q0. The PWM control circuit has a function of supplying a pulse signal modulated by the PWM method to the gate of the semiconductor switch Q0 to turn on / off the semiconductor switch Q0.

JP 2006-210835 A Japanese Patent Laid-Open No. 2007-4995 JP 2004-227951 A

  By the way, when the LED is lit for a long time by the lighting circuit shown in FIG. 5, the LED itself generates heat by the power consumed by the LED. With this heat generation, the temperature rises and the rated voltage value VF decreases. When the lighting circuit is placed in such a situation, since the power supply is controlled at a constant voltage, the voltage at both ends of the current limiting resistor R0 and the circuit current increase with a decrease in VF, and the light emission luminance of the LED fluctuates. There is a problem such as. Further, the ON resistance changes due to the heat generated by the semiconductor switch Q0, and as a result, the same problem as the LED temperature rise occurs. Furthermore, when the supply voltage fluctuates, the current value fluctuates as it is, which may be a factor that fluctuates the light emission luminance of the LED. In particular, the difference in VF of LEDs, which are semiconductors, increases due to lot variations, etc., so it is not easy to continuously emit light while maintaining a constant light emission luminance when a plurality of LEDs are connected to the load side. Absent.

  In general, the light emitting element is driven by a pulse with a fixed period on / off, but the pulse is further finely driven in the pulse of the on period with the fixed period on / off. Is not controlled while maintaining the vicinity of the peak current value close to the limit value of the driving capability of the light emitting element.

  Therefore, the applicant of the present application previously disclosed as Japanese Patent Application No. 2009-072163, a light source load section to which a light emitting element is connected, and a load capacity detection for detecting a rated voltage value of the light emitting element by a current supplied to the light source load section. And a signal processing for calculating a rated current value for steady driving of the light emitting element based on the rated voltage value detected by the load capacity detecting unit and a peak current value that can be passed to the light emitting element from the rated current value The control unit generates a first drive pulse having a square shape with a first on / off cycle that is pulse-width modulated based on the peak current value, and further includes an on-period of the first on / off cycle. A constant current pulse driving unit that generates a square-shaped second driving pulse with a switched second on / off period, and the constant current pulse driving unit includes the light source load unit. A charging / discharging circuit consisting of capacitance and inductance is provided on the output side to be connected, and charging is performed during the ON period of the first driving pulse and the second driving pulse that are driven so that the maximum amplitude of the pulse becomes the peak current value. A light source driving device has been proposed in which a current driven by a pulse signal generated by charging / discharging is applied to the light source load side by discharging in a period.

  According to the proposed light source driving device, even if a light emitting element whose rated voltage value or rated current value is not known is connected to the load capacity detecting unit, a minute current is flowed to the light emitting element step by step in advance. By referring to the table stored in the CPU, the rated voltage value of the light emitting element connected instantaneously can be detected, and further, the peak current value can be calculated from the detected rated voltage value by referring to the stored table. It has become. Then, the first and second drive pulses are generated based on the calculated peak current value, and the second drive pulse controlled by the peak current value is continuously applied to the light emitting element, so that the driving capability of the light emitting element is at a certain level. In this state, the heat generation amount and power consumption can be reduced.

Certainly, the light source device is automatically detected and driven by referring to a table stored in advance in the CPU even if the electrical characteristics such as the rated voltage of the connected light emitting element are unknown. Therefore, it is possible to target various light-emitting elements having different electrical characteristics.
However, it should be used in advance for products that use specified light-emitting elements such as light bulbs, downlights, floodlights, street lights, security lights, garden lights, security lights, guide lights, emergency lights, and stands. Since the rated voltage value of the light emitting element is known, detection of the rated voltage value and circuit configuration for calculating the peak current value from the detected rated voltage value with reference to a table or the like are unnecessary, In some cases, the size of the apparatus is increased and the cost is increased.

  Therefore, the present applicants have solved the above-described problems, and can be used even when the power supply voltage supplied from the external power supply source is a commercial power supply (AC 100V, 200V), a DC power supply, a dry battery, or the like. A control device was proposed as Japanese Patent Application No. 2009-212614. The proposed load drive control device includes a drive control unit including an output terminal that is connected to a load and applies a current, and an input terminal that inputs a DC voltage from an external power supply source. The step-up / step-down control unit that converts the DC voltage input at the input terminal into the rated voltage value of the load, and can flow to the load in a range that exceeds the rated current value of the load and does not exceed the absolute maximum rated current value. By performing pulse width modulation based on a preset peak current value, a first drive pulse having a square shape with a first on / off cycle defining the on period of the load is generated, and the first drive pulse A constant current pulse driver that generates a second drive pulse so that the maximum amplitude of the pulse becomes the peak current value by further switching during the ON period of A charging / discharging control unit having a capacitance, a resistor, and a diode between the loads, and a smoothing coil for the peak current value between the constant current pulse driving unit and the charging / discharging control unit, the maximum amplitude of the pulse is The first drive pulse and the second drive pulse that are driven to have the peak current value are charged during the ON period and discharged during the OFF period, thereby applying the current driven by the charge / discharge pulse signal to the load. It is characterized by doing.

Certainly, when the load driving device is intended for products that use a specified load (LED) such as a light bulb, downlight, or projector, the rated voltage value is detected and the peak current value is determined from the detected rated voltage value. It is no longer necessary to calculate with reference to a table or the like, so that the apparatus can be reduced in size and cost can be reduced.
However, when an electrolytic capacitor having a large capacitance and relatively inexpensive is used as the capacitance (capacitor) of the charge / discharge control unit, the life of the entire load driving device circuit is limited (limited) by this electrolytic capacitor. There was a case. However, if a ceramic capacitor with a longer life than an electrolytic capacitor is simply substituted, the capacitance to volume ratio is only half that of an electrolytic capacitor at most, so that sufficient charging can be ensured and at the same time withstand voltage can be secured. Problems sometimes occurred.

Therefore, as a result of repeated research on whether or not a ceramic capacitor having a life longer than that of an electrolytic capacitor can be used under the above-mentioned Japanese Patent Application No. 2009-212614, the applicant of the present application is related to inductance (coil). We paid attention and solved the above problem by compensating the capacity shortage of the ceramic capacitor with an inductance (coil).
That is, in order to solve the above-described problems, a load drive control device according to the present invention has a drive control having an output terminal connected to a load to apply a current and an input terminal for inputting a DC voltage from an external power supply source. A step-up / down control unit that converts a DC voltage input at the input terminal into a rated voltage value of the load, and exceeds a rated current value of the load and exceeds an absolute maximum rated current value. By generating a pulse width modulation based on a preset peak current value that can be passed through the load in a non-existing range, a first drive pulse having a square shape with a first on / off period defining the on period of the load is generated. In addition, by further switching during the ON period of the first drive pulse, a constant current pulse drive unit that generates the second drive pulse so that the maximum amplitude of the pulse becomes the peak current value, and A charge / discharge control unit having capacitance, resistance, and a diode is provided between the constant current pulse drive unit and the load, and a smoothing coil for the peak current value is provided between the constant current pulse drive unit and the charge / discharge control unit. The first driving pulse and the second driving pulse that are driven so that the maximum amplitude of the pulse becomes the peak current value are charged in the on period and discharged in the off period, thereby being driven by the pulse signal by the charge / discharge. In the load driving device for applying the current to the load, the capacitance of the charge / discharge control unit is a ceramic capacitor, and the capacitance of the ceramic capacitor is defined in relation to the coil.

  According to the load drive control device of the present invention, since a known load is used in advance, the capacitance (capacitor) of the charge / discharge control unit can secure a capacitance corresponding to the load in relation to the inductance (coil). Since it can be set to a ceramic capacitor, the electrical life of the load drive control device as a whole is greatly improved. Further, since the capacitance of this ceramic capacitor is reduced, the charging time when the load is lit is shortened. The effect that the rise time at the time of lighting becomes quick is also obtained. In addition, there is an effect that the dielectric breakdown due to the inrush DC voltage due to the surge to the ceramic capacitor generated when the LED is turned on can be reduced.

1 is a schematic block diagram of a load drive control device according to the present invention. It is a circuit diagram of the said load drive control apparatus. It is a drive timing of the said load drive control apparatus. It is a timing chart of each part based on the above-mentioned drive timing. It is a circuit diagram which shows the basic composition of the conventional LED drive control apparatus.

  Hereinafter, an embodiment of a load drive control device according to the present invention will be described in detail with reference to the accompanying drawings. Even if the load is other than a light emitting element such as a motor, a solenoid valve coil, or an actuator, the load drive control device is configured in the same manner as in this embodiment. FIG. 1 is a block diagram showing a schematic configuration of a load drive control device 1 of the present invention, FIG. 2 is a circuit diagram showing details of the load drive control device 1, FIG. 3 is a drive timing diagram, and FIG. It is a timing chart. As shown in FIG. 1, the load drive control device 1 of the present invention includes a load 20 whose electrical characteristics such as a rated voltage value and a rated current value are known. Hereinafter, a light emitting element (LED) will be described as an example of the load 20. In addition, the load drive control device 1 includes an output terminal 11 that is connected to the light emitting element 20 and applies a current to the light emitting element 20, and an input terminal 12 that inputs the DC voltage V 0 from the external power supply source 100. A drive control unit 10 is provided. The light emitting element 20 is incorporated by appropriately selecting the type, quantity, etc. according to the use such as 1 W, 2 W, 3 W, 4 W, 5 W,. For example, in the case of an incandescent lamp 30W equivalent, one light emitting element of around 4 W or five light emitting elements of 1 W are selected and connected in series. FIG. 1 shows an example in which one 4 W LED is selected as the light emitting element 20. From the specifications made by the light emitting element manufacturer A, etc., when the light emitting element 20 is 4 W, the rated voltage value VF is easily found to be 9.3 V and the rated current value IF is 0.48 A. Moreover, even if a light emitting element selects the product made from B company and the product made from C company besides the product made from A company, the rated voltage value and rated current value of LED which were selected from each specification etc. can be known beforehand.

  On the other hand, the external power supply source 100 is selected from commercial AC voltage (100V system, 200V system), DC voltage (3V-48V system, etc.) and dry battery (1.5V-3V system, etc.) according to the application of the product. A power supply will be used. When a commercial AC voltage is used, since the LED is operated by DC driving, it is converted from AC to DC via a general rectifier circuit 101 provided on the external power supply source 100 side, and drive control is performed. It is supplied to the input terminal 12 of the unit 10. When a DC voltage power supply and a dry battery power supply are used, the DC voltage V0 is input to the input terminal 12 as it is.

  The drive control unit 10 includes a step-up / down control unit 13, a constant current pulse drive unit 14, and a charge / discharge control unit 15. The step-up / down control unit 13 controls the voltages at both ends (13a, 13b) of the step-up / down control unit 13 so that the current I1 flowing through the circuit and the light emitting element 20 becomes the set current IF. When the current I1 is lower than the set current IF, it operates as a boost converter and controls the current I1 to be equal to the set current IF. Conversely, when the current I1 is higher than the set current IF, it operates as a step-down converter and controls the current I1 to be equal to the set current IF. Therefore, the voltage VF controlled by the step-up / step-down control unit 13 is output to the constant current pulse driving unit 14.

  The constant current pulse drive unit 14 is between the preset rated current value IF of the light emitting element 20 and the absolute maximum rated current value Imax that can be flowed within a range in which the preset light emitting element 20 in pulse driving described later is not destroyed. Thus, the drive pulse driven at the peak current value Ip as a value closer to the absolute maximum rated current value without exceeding the absolute maximum rated current value Imax is output to the charge / discharge control unit 15. The charge / discharge control unit 15 applies to the light emitting element 20 a current having a light emission period waveform W1 having the peak current value Ip as the maximum amplitude. As a result, the light emitting element 20 can be driven to emit light in a continuously stable manner with high efficiency while suppressing power consumption.

The peak current value Ip on the basis of the rated voltage value VF is only required to maintain the relationship of IF <Ip <Imax. However, in order to obtain the maximum effect, in consideration of safety, Ip = k * Imax However, it is preset as k = 0.9. Of course, the coefficient k can take a range of 0 <k <1 depending on the situation, but preferably a range of 0.5 <k <1, more preferably 0.7 <k <1. From this result, the peak current value Ip for actually driving the light emitting element 20 with high efficiency is set. The coefficient k can also be set from the outside by an adjustment device (not shown) such as a variable resistor, a trimmer, or a dip switch connected to the external terminal of the drive control unit 10.

Further, as described above, as means other than setting the peak current value Ip in advance as a predetermined value, a rated current value reference table (VF-IF table) or an absolute maximum rated current value reference table (IF-Imax) is stored in the memory of the CPU. Table) can be stored and calculated by program processing based on these reference tables. A rated voltage value VF and a rated current value IF are set in the VF-IF table, and the rated current value IF and an absolute maximum rated current value Imax are set in the IF-Imax table.

Here, the rated current value IF is a current value that allows the light emitting element 20 to emit light with a constant brightness in a stable state, and the rated voltage value VF is a voltage applied to the light emitting element 20 at that time. Value. The absolute maximum rated current value Imax is a maximum allowable value that can guarantee the operation of the light emitting element 20 under certain conditions. If this value is exceeded, the element may be destroyed. It is a value specified so that it does not exceed even if it exists. The absolute maximum rated current value Imax is a maximum allowable value that can be guaranteed under the driving conditions of the first driving pulse and the second driving pulse, which will be described later, according to the specification of an LED chip manufacturer such as the aforementioned company A. Unlike the specified absolute maximum rated current value, it can take several times the value.
Therefore, the peak current value Ip in the present invention is obtained by adding a coefficient k as a safety factor to the absolute maximum rated current value Imax obtained in advance under the driving conditions of the first and second driving pulses of the light emitting element 20 to be used. The value determined by

Subsequently, as shown in FIG. 3, a square light emission period signal (first drive pulse) P <b> 1 for driving the light emitting element 20 in a pulse manner is generated. The first drive pulse P1 has a continuous first on / off period T1 that is pulse-width modulated by the first drive circuit 23 of the constant current pulse drive unit 14, and includes a period during which current flows (on period) The period during which no current flows (off period) is repeated continuously. For example, the first on / off period T1 is set to about 200 Hz, and the duty ratio is set so that the off period is 9 (90%) with respect to the on period of 1 (10%). The first on / off period T1 is appropriately set according to the driving capability of the light emitting element 20.

  The first drive pulse P1 is switched at a high speed in the first on period, so that a light emission drive signal having a square shape having a second on / off period T2 in which a current flowing period is further intermittently interrupted. A second drive pulse P2 is generated. The second on / off period T2 is, for example, about 300 kHz under the condition of T1 described above, and the duty ratio is such that the on period is 1 and the off period is 9 like the first drive pulse P1. Set to The second drive pulse P2 is controlled and output with an amplitude width based on the peak current value Ip set in accordance with the drive capability such as the type and number of the light emitting elements 20, like the first drive pulse P1. Also, as shown in FIGS. 3 and 4, the second drive pulse P2 passes through the RC integration circuit 27, thereby causing a triangular light emission drive waveform W2 that repeats charging / discharging in the second on / off period T2 and Become. Furthermore, a current with a triangular wave-like light emission period waveform W1 that repeats charging / discharging at the first on / off period T1 is output from the pulse by this light emission drive waveform W2. In this way, by applying a current based on the light emission periodic waveform W1 having the peak current value Ip to the maximum amplitude width to the light emitting element 20, the light emitting element 20 is continuously stabilized with high efficiency while suppressing power consumption. Light emission can be driven.

  The drive controller 10 of the present invention is controlled by the constant current pulse driver 14 within a range where the peak current value Ip satisfies the relationship of IF <Ip <Imax, and the peak current value Ip is switched at a predetermined duty ratio. It is configured to let you.

  As shown in FIG. 2, the constant current pulse driving unit 14 includes a constant current control unit 21, a first switching element Q1, and a second switching element Q2. The constant current control unit 21 monitors the voltage conversion value V1 of the set current value IF, and outputs it to the first drive circuit 23 and the second drive circuit 24 so as to keep the current IF flowing through the light emitting element 20 constant. The peak current value Ip is controlled. The first switching element Q1 is for generating a first drive pulse P1 having a first on / off cycle T1, and the current signal increased or decreased by the step-up / down converter via the first drive circuit 23. By switching at a predetermined timing, a ratio (duty) between the on period and the off period is set. The first on / off period T1 is controlled to be about 200 Hz. Further, the duty is controlled so as to be the rated luminance of the light emitting element 20, but the amount of heat generation and power consumption can be reduced by setting the ON period to be about 50% or less. it can. In this embodiment, the duty ratio is set so that the on period is 1 (10%) and the off period is 9 (90%).

  The second switching element Q2 is for generating a second drive pulse P2 having a second on / off period T2, and is operable while the first switching element Q1 is on. Yes. By this switching, the second on / off period T2 is 300 kHz, and the duty ratio is controlled so that the on period is 1 (10%) and the off period is 9 (90%).

  The drive control unit 10 is provided with a charge / discharge control unit 15 including a capacitance C1 made of a ceramic capacitor, a resistor R1, and a diode D1 on the output side connected to the electrode terminal 11 on the light emitting element 20 side. In the charge / discharge control unit 15, the current flowing through the light emitting element 20 is also charged into the ceramic capacitor C 1 through the resistor 1 each time the first switching element Q 1 and the second switching element Q 2 are turned on. Then, while the first switching element Q1 and the second switching element Q2 are turned off, the charge charged in the capacitor C1 is discharged, and a current flows through the light emitting element 20. As a result, a constant amount of current can be continuously supplied to the light emitting element 20 not only in the on period but also in the off period due to the switching of the first switching element Q1 and the second switching element Q2. For this reason, since the driving current is an intermittent square wave pulse, a constant current continuously flows through the light emitting element 20, so that the light emission luminance can be maintained constant and the power consumption can be reduced. It becomes possible. The coil L1 and the diode D2 are provided to smooth the peak current value Ip flowing through the LED 20 when the second switching element Q2 is turned on. The diode D2 is provided as a buck converter, and has a function of regenerating the current flowing in the light emitting element 20 to I1 while the second switching element Q2 is off.

Further, the coil L1 and the ceramic capacitor C1 are defined in the following Equation 1 associated with the resonance frequency f.
Therefore, even when the ceramic capacitor C1 having a small capacity is used, the current can be maximized at the series resonance frequency by maintaining the relationship defined by the expression (1) in relation to the coil L1, and the light emission periodic waveform W1. In addition, the peak current Ip can be stably applied to the load without affecting the light emission drive waveform W2.

  As shown in FIG. 2, the load current detection unit 16 includes a current detection element R2, an RC integration circuit 27, and a differential amplifier 28. The current detection element R2 uses a highly accurate shunt resistor, and detects a current flowing through the light emitting element 20 by switching of the second switching element Q2. In the RC integration circuit 27, the detection current detected by the current detection element R2 is integrated by the on / off cycle of the second switching element Q2. The differential amplifier 28 outputs a detection voltage V1 amplified by taking the difference between the signal integrated by the RC integration circuit 27 and the reference voltage source 32. The detection voltage V1 is sent to the constant current control unit 21.

  Next, the drive operation procedure of the load body drive control device 1 will be described with reference to FIGS. With the light emitting element 20 connected between the output terminals 11 of the drive control unit 10, the DC voltage V 0 from the external power supply source 100 is connected to the input end of the drive control unit 10, and the load body drive control device 1 is connected. Launch and turn on. When the external power supply source 10 is turned on, the first switching element Q1 is turned on / off through the first drive circuit 23 by the peak current value Ip signal output from the constant current control unit 21 in the constant current pulse driving unit 14. . By turning on / off the first switching element Q1, the second switching circuit Q2 is turned on / off through the second drive circuit 24 at high speed. The integrated pulse current Ip that has passed through the second switching circuit Q2 is the voltage Vrc obtained by integrating the voltage generated at the reference numeral 16a in the circuit through the resistor R2 of the load current detection unit 16 by the RC integration circuit 27. The voltage Vref based on the reference voltage source 32 is compared by the differential amplifier 28, and the output voltage V1 controlled so that the voltage Vrc becomes the voltage Vref is output from the differential amplifier 28 to the constant current control unit 21. In the range where the peak current value Ip satisfies the relational expression IF <Ip <Imax as described above, in particular, by maintaining a state close to Imax, light is emitted in a stable state while maximizing brightness. It becomes possible.

  By this switching, a current based on the light emission drive waveform W2 generated by the second drive pulse P2 switched at a higher speed in the first drive pulse P1 that determines the light emission period of the light emitting element 20 is applied. The light emission drive waveform W2 is a triangular wave that is RC-integrated based on a square pulse wave that periodically repeats an on period and an off period, so that the light emission luminance is kept at a high level while suppressing overall power consumption and heat generation. The LED can be continuously driven in the maintained state.

  Further, the light emitting element 20 controls the width (duty) at which the first switching element Q1 and the second switching element Q2 in the constant current pulse driving unit 14 are turned on or charged / discharged by a control signal from the outside. By adjusting the capacitance capacity in the control unit 15 or the like, it is possible to adjust the light emission amount, the light emission luminance, and the like.

  As an example, when a load drive control device using a light emitting element as a load of the present invention is applied to an LED bulb with a base, the input end of the drive control unit 10 is connected to the base, and the load drive control device 1 By covering the whole with a case including a transparent or translucent cap, the LED bulb can be easily obtained.

As described above, according to the load drive control device of the present invention, instead of continuously supplying a constant current according to the characteristics and number of light emitting elements connected as a load to the light emitting elements, A ceramic capacitor C1 provided with a capacitor for switching a pulse signal whose ON / OFF of the peak current value Ip changes at high speed, charging in the ON period of the pulse and discharging in the OFF period, in relation to the coil L1 Thus, the light emitting element is controlled to emit light. As a result, the life of the entire circuit can be significantly improved compared to conventional electrolytic capacitors, and dielectric breakdown due to surge or pulse abnormal voltage generated in the capacitor C1 is less likely to occur, and the capacitance is reduced. As a result, the rise time to the rated voltage VF of the load LED is shortened.

DESCRIPTION OF SYMBOLS 1 Load drive control apparatus 10 Drive control part 11 Output end 12 Input end 13 Buck-boost control part 14 Constant current pulse drive part 15 Charge / discharge control part 16 Load current detection part 20 Load 21 Constant current control part 23 1st drive circuit 24 1st 2 drive circuit 27 RC integration circuit 28 differential amplifier 32 reference voltage source 100 external power supply source 101 external rectifier Q1 first switching element Q2 second switching element R1 resistor R2 current detection element C1 ceramic capacitor (capacitance)
L1 coil (inductance)
D1, D2 Diode P1 First drive pulse P2 Second drive pulse T1 First on / off cycle T2 Second on / off cycle W1 Light emission cycle waveform W2 Light emission drive waveform V1 Detection voltage VF Rated voltage value I1 Detection current IF Rating Current value Ip Peak current value Imax Absolute maximum rated current value

Claims (1)

A drive control unit having an output terminal connected to a load for applying a current and an input terminal for inputting a DC voltage from an external power supply source, wherein the drive control unit is a DC voltage input at the input terminal; And a step-up / down control unit for converting the load into a rated voltage value of the load, and a pulse based on a preset peak current value that can flow to the load in a range that exceeds the rated current value of the load and does not exceed the absolute maximum rated current value By performing width modulation, a first drive pulse having a square shape with a first on / off period defining the on period of the load is generated, and further switching is performed during the on period of the first drive pulse. A constant current pulse driving unit that generates a second driving pulse so that the maximum amplitude of the pulse becomes the peak current value; and a capacitance, a resistor, and a die between the constant current pulse driving unit and the load. A charge / discharge control unit having an aode and a smoothing coil for the peak current value between the constant current pulse drive unit and the charge / discharge control unit are driven so that the maximum amplitude of the pulse becomes the peak current value. In the load driving device for applying the current driven by the pulse signal by the charging / discharging to the load by charging in the on period of the first driving pulse and the second driving pulse and discharging in the off period, the charging / discharging A load drive control device characterized in that the capacitance of the controller is a ceramic capacitor, and the capacitance of the ceramic capacitor is defined in relation to the coil.