CN103491668A

CN103491668A - Light source control device

Info

Publication number: CN103491668A
Application number: CN201310216840.7A
Authority: CN
Inventors: 村松隆雄; 武田仁志; 伊藤昌康; 村上健太郎
Original assignee: Koito Manufacturing Co Ltd
Current assignee: Koito Manufacturing Co Ltd
Priority date: 2012-06-11
Filing date: 2013-06-03
Publication date: 2014-01-01
Anticipated expiration: 2033-06-03
Also published as: JP2014017463A; JP6030922B2; CN104902630B; EP2675247A1; CN103491668B; EP2800457B1; EP2800457A3; EP2675247B1; CN104902630A; EP2800457A2

Abstract

The present invention provides a light source control device which can cope appropriately even though the wirings around a light source or the bypass switches are in poor conduction. The semi-conductor light source control device comprises a driving circuit for generating a driving current; a second bypass switch (110-2) in parallel connection with a second LED (2-2); and a third bypass switch (110-3) in parallel connection with a third LED (2-3). When the second bypass switch (110-2) is cut off and the third bypass switch (110-3)is turned on, the polarity of a current flowing through a second bypass connecting wiring (280-2) is reverse with the polarity of the current flowing through the second bypass connecting wiring when the second bypass switch (110-2) is turned on and the third bypass switch (110-3) is cut off. The semi-conductor light source control device is configured to force the second and third bypass switches to be turned on when the second bypass connecting wiring is in poor conduction.

Description

Light source control device

Technical field

The present invention relates to a kind of light source control device that light source is controlled.

Background technology

In recent years, in the lamps apparatus for vehicle such as headlamp, replace the existing Halogen lamp LED with filament and the lower LED(Light Emitting Diode of longer service life and consumed power) etc. semiconductor light sources.The luminous degree of LED is that brightness is relevant to the size of current that flows through LED, therefore, in the situation that LED is used as to light source, needs the lamp circuit for the electric current that flows through LED is regulated.

The applicant has proposed a kind of technology in patent documentation 1, and it adopts the LED matrix for the luminous intensity distribution that makes headlamp is variable, carry out enough meticulous distribution controls as light source, makes each LED light a lamp separately/turn off the light.In the lamp circuit of patent documentation 1 record, be provided with in parallel by-pass switch with each LED, realize lighting a lamp separately/turning off the light of LED by this by-pass switch on/off.

Patent documentation 1: TOHKEMY 2011-192865 communique

In the situation that the bypass mode that adopts patent documentation 1 to put down in writing, the distribution more complicated of LED periphery.If distribution is complicated, there is the problem of the possibility increase that comes in contact the poor flows such as bad or broken string.

Summary of the invention

The present invention proposes in view of above-mentioned condition, even the light source control device that provides a kind of light source or by-pass switch distribution generation poor flow on every side also can suitably tackle is provided its purpose.

Mode of the present invention relates to light source control device.This light source control device has: drive circuit, and the drive current of a plurality of semiconductor light sources that are connected in series is flow through in its generation; The 1st by-pass switch, the part in itself and a plurality of semiconductor light sources is connected in parallel; And the 2nd by-pass switch, itself and described the 1st by-pass switch are connected in series, and are connected in parallel with the another part in a plurality of semiconductor light sources.The connection distribution be connected with a part in a plurality of semiconductor light sources and the connected node between the another part in a plurality of semiconductor light sources for the connected node by between the 1st by-pass switch and the 2nd by-pass switch, at the 1st by-pass switch, disconnect and the 2nd by-pass switch flows through the polarity of the electric current that connects distribution while connecting, with the 1st by-pass switch, connect and the 2nd by-pass switch to flow through the polarity of the electric current that connects distribution while disconnecting contrary.It is configured to, in the situation that connect distribution generation poor flow, makes forcibly the 1st by-pass switch and the 2nd the two connection of by-pass switch.

According to this mode, can in the situation that connect distribution generation poor flow, make forcibly the 1st by-pass switch and the 2nd the two connection of by-pass switch.

Another way of the present invention is also a kind of light source control device.This device has: drive circuit, and the drive current of a plurality of semiconductor light sources that are connected in series is flow through in its generation; By-pass switch, at least a portion in itself and a plurality of semiconductor light sources is connected in parallel; Main control circuit, it makes periodically on/off of by-pass switch when usually lighting a lamp; And abnormality detection auxiliary circuit, itself in the situation that the both end voltage of the by-pass switch of by-pass switch while disconnecting lower than the 1st voltage or higher than 2nd voltage higher than the 1st voltage, the amount of the electric charge that capacitor is kept with the 1st time constant to the 1st towards variation, in the situation that the amount of the electric charge that can't make capacitor keep with the 1st time constant to the 1st towards changing, the amount of the electric charge that capacitor is kept with 2nd time constant longer than the 1st time constant to the 1st the towards the opposite the 2nd towards variation.The both end voltage of main control circuit based on capacitor determines whether abnormal, in the situation that be judged to be, occurred extremely, makes forcibly by-pass switch connect.

According to this mode, can utilize difference between the 1st time constant and the 2nd time constant, determine whether and occurred extremely.

In addition, the combination in any of above-mentioned inscape or by inscape of the present invention or be described in phase double replacement between device, method, system etc., be all effective as mode of the present invention.

The effect of invention

According to the present invention, even the light source control device that can provide the distribution generation poor flow around light source or by-pass switch also can suitably tackle.

The accompanying drawing explanation

Fig. 1 means the circuit diagram of the structure of optical semiconductor source control device that execution mode is related and connected parts.

Fig. 2 means the circuit diagram of structure of the hysteresis amplitude initialization circuit of Fig. 1.

Fig. 3 means the absolute value of driving voltage and the curve chart of the relation between bucking voltage.

Fig. 4 means the circuit diagram of structure of the down converter drive circuit of Fig. 1.

Fig. 5 means the circuit diagram of the structure of the 2nd bypass circuit of Fig. 1 and the 3rd bypass circuit.

(a) of Fig. 6 means to (c) curve chart that the time of drive current changes.

The 2nd by-pass switch when Fig. 7 means the PWM dim light drives the sequential chart of the variation of signal and the 2nd anomaly detection signal.

Fig. 8 means the circuit diagram of the structure of the semiconductor light sources lamp circuit that Comparative Examples is related.

(a) of Fig. 9 means the circuit diagram of the structure of the optical semiconductor source control device that the 1st, the 2nd and the 3rd variation is related to (c).

Figure 10 means the circuit diagram of the structure of optical semiconductor source control device that the 4th variation is related and connected parts.

Figure 11 means the circuit diagram of structure of the 2nd bypass circuit of the optical semiconductor source control device that the 5th variation is related.

Figure 12 means that the light a lamp sequential chart of variation of light-off control signal of the 2nd in the situation of broken string occurs 2LED.

The explanation of label

6 Vehicular accumulator cells, 8 mains switches, 100 optical semiconductor source control devices, 102 flyback adjusters, 104 down converters, 106 control circuits, 108 current sense resistors, 128 output capacitors, 142 fly-wheel diodes, 144 inductors.

Embodiment

Below, to each identical or the inscape, parts, the signal that are equal to shown in the drawings, mark same numeral and suitably omit repeat specification.In addition, in each accompanying drawing, will omit and be meaned for the part of the unessential parts of explanation.In addition, for the label of the marks such as voltage, electric current or resistance, as required and sometimes for meaning each magnitude of voltage, current value or resistance value.

In this manual, so-called " state that components A is connected with part B ", physically direct-connected situation, also comprise the situation that components A is connected via other parts that can not exert an influence to electrical connection state indirectly with part B except components A and part B.In the same manner, so-called " parts C is arranged on the state between components A and part B ", except components A and parts C or part B and the direct-connected situation of parts C, also comprise situation about indirectly connecting via other parts that can not exert an influence to electrical connection state.

It is the drive current of LED that a plurality of semiconductor light sources that are connected in series are flow through in the related optical semiconductor source control device generation of execution mode.With each LED, by-pass switch is set in parallel.If by-pass switch is connected (disconnection), corresponding LED becomes light-off (lighting a lamp) state.Be provided with bypass with connecting distribution between the connected node between 2 by-pass switches of the connected node between 2 adjacent LED and correspondence.The optical semiconductor source control device is configured to, and when bypass uses the connection distribution that broken string or loose contact occur, forces 2 by-pass switches connections that this bypass is connected with the connection distribution.Thus, in the situation that above-mentioned poor flow occurs, can make relevant LED become the light-off state.

Fig. 1 means the circuit diagram of the structure of optical semiconductor source control device 100 that execution mode is related and connected parts.Optical semiconductor source control device 100 is supplied with drive current Iout to a plurality of (N) the vehicle mounted LED2-1 to 2-N be connected in series, and these LED are lit a lamp.N is more than or equal to 2 natural number.Optical semiconductor source control device 100 and a N LED2-1 to 2-N are equipped in the lamps apparatus for vehicle such as headlight.Optical semiconductor source control device 100 is connected with Vehicular accumulator cell 6, mains switch 8.

Vehicular accumulator cell 6 generation 12V(or 24V) direct-flow storage battery voltage (supply voltage) Vbat.Mains switch 8 is to be set to the relay switch of being controlled for the on/off to N LED2-1 to 2-N integral body, with Vehicular accumulator cell 6, in series arranges.If mains switch 8 is connected,, from the positive terminal of Vehicular accumulator cell 6, using battery tension Vbat as input voltage, to optical semiconductor source control device 100, supply with.The negative terminal of Vehicular accumulator cell 6 is connected, carries out ground connection with the fixed voltage terminal.

Each LED2-1 to 2-N is connected with electrostatic protection Zener diode 252-1 to 252-N side by side and inversely.That is, the negative pole of the 1st electrostatic protection Zener diode 252-1 is connected with the positive pole of 1LED2-1, and the positive pole of the 1st electrostatic protection Zener diode 252-1 is connected with the negative pole of 1LED2-1.For the 2nd electrostatic protection Zener diode 252-2 to the N electrostatic protection Zener diode 252-N, connected similarly.The electrostatic protection Zener diode protects corresponding LED can not cause fault because of static.

It is flyback adjuster 102, down converter 104, control circuit 106, current sense resistor 108, a N bypass circuit 270-1 to 270-N and bypass drive circuit 112 that optical semiconductor source control device 100 has switching regulaor.106 pairs of flyback adjusters 102 of control circuit and down converter 104 are controlled, and comprise flyback drive circuit 134, down converter drive circuit 136 and hysteresis amplitude initialization circuit 138.Bypass drive circuit 112 is realized by microcomputer.

Flyback adjuster 102 is voltage regulators, and the battery tension Vbat of input is transformed to target voltage Vt output.The lead-out terminal of the high-side of flyback adjuster 102 is the ground connection side, and therefore, target voltage Vt is the voltage of lead-out terminal that puts on the low level side of flyback adjuster 102, has negative polarity.Flyback adjuster 102 comprises input capacitor 114, the 1st switch element 116, input transformer 124, output diode 126, output capacitor 128, voltage detecting diode 130 and voltage detecting capacitor 132.

Input capacitor 114 is arranged in parallel with Vehicular accumulator cell 6, and battery tension Vbat is carried out to smoothing.More particularly, input capacitor 114 is arranged near input transformer 124, realizes the function of for the switch motion of flyback adjuster 102, carrying out the voltage smoothing.

Winding 118 and the 1st switch element 116 of input transformer 124 are connected in series, and this series circuit is connected in parallel with respect to Vehicular accumulator cell 6 and input capacitor 114.For example the 1st switch element 116 is by N passage MOSFET(Metal Oxide Semiconductor Field Effect Transistor) form.One end of the secondary winding 120 of input transformer 124 is connected with an end of output capacitor 128, and the other end of secondary winding 120 is connected with the positive pole of output diode 126.The other end of output capacitor 128 is connected with the negative pole of output diode 126.One end of output capacitor 128 is connected with the lead-out terminal of the low level side of flyback adjuster 102, applies target voltage Vt.The other end of output capacitor 128 is connected with the lead-out terminal of the high-side of flyback adjuster 102.

The control terminal (grid) of the 1st switch element 116 is applied to the leading portion control signal S1 of the square wave shape generated by flyback drive circuit 134.The 1st switch element 116 is effectively connected during high level when (assert) at leading portion control signal S1, when cancelling, disconnects during low level.

Winding 122, voltage detecting diode 130 and the voltage detecting capacitor 132 for voltage detecting of input transformer 124 form the cathode voltage testing circuit, and this cathode voltage testing circuit is detected as positive polarity voltage for the size to target voltage Vt.Voltage detecting is used an end ground connection of winding 122, and the other end is connected with the positive pole of voltage detecting diode 130.The negative pole of voltage detecting diode 130 is connected with an end of voltage detecting capacitor 132.The other end ground connection of voltage detecting capacitor 132.An end at voltage detecting capacitor 132 applies the positive voltage corresponding with the absolute value of target voltage Vt.This voltage is supplied to flyback drive circuit 134 as detecting voltage Vd.

Flyback drive circuit 134 is based on detecting voltage Vd, and the Voltage Feedback carried out for target voltage Vt being remained to constant is controlled.Frequency and the duty ratio of 134 couples of leading portion control signal S1 of flyback drive circuit are regulated, so that target voltage Vt is close to the setting voltage of for example-100V left and right.

Down converter 104 is arranged on the back segment of flyback adjuster 102, comprises the 2nd switch element 140, fly-wheel diode 142 and inductor 144, but does not comprise the capacitor of the level and smooth use of output voltage.

The 2nd switch element 140 for example consists of N passage MOSFET.The control terminal of the 2nd switch element 140 is applied to the back segment control signal S2 of the square wave shape generated by down converter drive circuit 136.The 2nd switch element 140 is connected when back segment control signal S2 is high level, when low level, disconnects.The drain electrode of the 2nd switch element 140 is connected with the lead-out terminal that the high-side of output capacitor 128 is the high-side of flyback adjuster 102.The source electrode of the 2nd switch element 140 is connected with the negative pole of fly-wheel diode 142.

The positive pole of fly-wheel diode 142 is connected with an end of inductor 144.Connected node between one end of the positive pole of fly-wheel diode 142 and inductor 144, the lead-out terminal that is the low level side of flyback adjuster 102 with the low level side of output capacitor 128 is connected.The other end of inductor 144 is connected with the negative side of a N LED2-1 to 2-N.

Current sense resistor 108 is arranged on the path of drive current Iout.Connected node between the negative pole of one end of current sense resistor 108 and the source electrode of the 2nd switch element 140 and fly-wheel diode 142 is connected.The other end ground connection of current sense resistor 108, and be connected with the side of the positive electrode of a N LED2-1 to 2-N.Produce the voltage drop Vm be directly proportional to drive current Iout in current sense resistor 108.

Due to the side of the positive electrode ground connection of a N LED2-1 to 2-N, so the other end that is inductor 144 in the negative side of a N LED2-1 to 2-N applies the driving voltage Vout of negative polarity.When usually lighting a lamp, driving voltage Vout becomes the negative voltage that size is suitable with the forward drop Vf of LED quantity in luminance (=corresponding by-pass switch disconnection) * 1 LED.

Down converter drive circuit 136, based on voltage drop Vm, carries out for drive current Iout is remained on to the Current Feedback Control in the rated current scope.As down converter drive circuit 136, if the size of drive current Iout surpasses the upper current limit value Ith1 of regulation, disconnect the 2nd switch element 140, if the size of drive current Iout, lower than the floor level of electric current Ith2 also less than upper current limit value Ith1, is connected the 2nd switch element 140.As down converter drive circuit 136, if the size of drive current Iout surpasses upper current limit value Ith1, back segment control signal S2 is set to low level, if the size of drive current Iout, lower than floor level of electric current Ith2, is set to high level by back segment control signal S2.

Hysteresis amplitude initialization circuit 138 is based on driving voltage Vout, and the difference of upper current limit value Ith1 and the floor level of electric current Ith2 amplitude, ao I that lags behind is set.Hysteresis amplitude initialization circuit 138 is in the situation that the absolute value of the driving voltage Vout voltage threshold Vth also little lower than the absolute value than target voltage Vt, the amplitude, ao I that makes to lag behind becomes large and increases along with the absolute value of driving voltage Vout, in the situation that the absolute value of driving voltage Vout surpasses voltage threshold Vth, the amplitude, ao I that makes to lag behind becomes large and reduces along with the absolute value of driving voltage Vout.

Fig. 2 is the circuit diagram that the structure of hysteresis amplitude initialization circuit 138 is shown.Hysteresis amplitude initialization circuit 138 has the 1st operational amplifier the 146, the 1st diode the 148, the 1st resistance the 150, the 2nd resistance the 152, the 3rd resistance the 154, the 4th resistance the 156, the 5th resistance 158 and reference voltage source 160.An end at the 3rd resistance 154 applies positive control power source voltage Vcc.The other end of the 3rd resistance 154 is connected with an end of the 2nd resistance 152, an end of the 5th resistance 158 and an end of the 4th resistance 156.The other end ground connection of the 4th resistance 156.The other end at the 5th resistance 158 applies driving voltage Vout.The other end of the 2nd resistance 152 is connected with the reversion input terminal of the 1st operational amplifier 146.The reversion input terminal of the 1st operational amplifier 146 is connected with the positive pole of the 1st diode 148 via the 1st resistance 150.The negative pole of the 1st diode 148 is connected with the lead-out terminal of the 1st operational amplifier 146.Non-reversion input terminal to the 1st operational amplifier 146 applies the reference voltage V ref generated by reference voltage source 160.The voltage that is applied to the positive pole of the 1st diode 148 is called to bucking voltage Voffset.As described later, bucking voltage Voffset is corresponding with hysteresis amplitude, ao I, and bucking voltage Voffset is higher, and the amplitude, ao I that lags behind is larger.

Resistance value for the 1st operational amplifier 146 peripheries, with become the 3rd differential resistance the 154, the 4th resistance 156 of reference voltage V ref and the value of the 5th resistance 158 and compare, the value of the 1st resistance 150, the 2nd resistance 152 that makes to determine magnification ratio is fully large, so that feedback current can not exert an influence to the differential of reference voltage V ref.

Fig. 3 means the absolute value of driving voltage Vout and the curve chart of the relation between bucking voltage Voffset.At the absolute value of the driving voltage Vout of negative polarity hour, the voltage of the common connected node of the 3rd resistance the 154, the 4th resistance 156 and the 5th resistance 158 is larger with respect to reference voltage V ref, therefore, the 1st operational amplifier 146 carries out electric current and reduces (sink) and bucking voltage Voffset is reduced.When the voltage of common connected node equates with reference voltage V ref, it is maximum that bucking voltage Voffset reaches.

In order to realize when the absolute value of driving voltage Vout becomes voltage threshold Vth, hysteresis amplitude, ao I is that bucking voltage Voffset reaches maximum control, reference voltage V ref is set as to the voltage of the common connected node when the absolute value of driving voltage Vout equals voltage threshold Vth.Especially, at the setting voltage of flyback adjuster 102, be-during 100V reference voltage V ref to be set as to the voltage of the common connected node when the driving voltage Vout=-Vth=-50V.

Surpass voltage threshold Vth if the absolute value of driving voltage Vout increases, the 1st operational amplifier 146 is not acted on, directly by the voltage of common connected node voltage Voffset by way of compensation.Hysteresis amplitude initialization circuit 138 is delivered to down converter drive circuit 136 by the bucking voltage Voffset that the above-mentioned absolute value with respect to driving voltage Vout is changed with the mountain peak shape, thereby I is controlled to the hysteresis amplitude, ao, the switching frequency of down converter 104 is fallen within the limits prescribed.

Fig. 4 is the circuit diagram that the structure of down converter drive circuit 136 is shown.Down converter drive circuit 136 has the 2nd operational amplifier 162, comparator 164, gate drivers 166, the 1st current mirror circuit the 170, the 7th resistance the 172, the 8th resistance the 174, the 10th resistance the 178, the 12nd resistance the 182, the 13rd resistance 184, l npn type bipolar transistor the 190, the 3rd switch element the 202, the 4th switch element 204 and the 2nd current mirror circuit 206.

Non-reversion input terminal to the 2nd operational amplifier 162 applies bucking voltage Voffset.The lead-out terminal of the 2nd operational amplifier 162 is connected with the base stage of 1npn type bipolar transistor 190, and the reversion input terminal is connected with the emitter of 1npn type bipolar transistor 190.One end of the 8th resistance 174 is connected with the emitter of 1npn type bipolar transistor 190, other end ground connection.The collector electrode of 1npn type bipolar transistor 190 is connected with the 1st current mirror circuit 170 via the 7th resistance 172.

The 1st current mirror circuit 170 has the 6th resistance the 168, the 9th resistance the 176, the 11st resistance 180,1pnp type bipolar transistor 192,2pnp type bipolar transistor 194 and 3pnp type bipolar transistor 196.These circuit elements interconnect in the mode that forms known current mirror circuit.The electric current that the 1st current mirror circuit 170 will flow through the 7th resistance 172 is as input, and the electric current that will flow through the electric current of the 10th resistance 178 and flow through the 3rd switch element 202 is as output, makes the size of the size of input current and output current about equally.

The 2nd current mirror circuit 206 has the 14th resistance the 186, the 15th resistance 188,2npn type bipolar transistor 198 and 3npn type bipolar transistor 200.These circuit elements interconnect in the mode that forms known current mirror circuit.The electric current that the 2nd current mirror circuit 206 will flow through the 10th resistance 178, as input, will flow through the electric current of the 4th switch element 204 as output, make the size of the size of input current and output current about equally.

The 3rd switch element 202 for example consists of P passage MOSFET.The 4th switch element 204 for example consists of N passage MOSFET.The source electrode of the 3rd switch element 202 is connected with the 1st current mirror circuit 170.The inversion output terminal sub-connection of the grid of the 3rd switch element 202 and comparator 164.The drain electrode of the 3rd switch element 202 is connected with the drain electrode of the 4th switch element 204.The inversion output terminal sub-connection of the grid of the 4th switch element 204 and comparator 164.The source electrode of the 4th switch element 204 is connected with the 2nd current mirror circuit 206.

The 12nd resistance 182 and the 13rd resistance 184 are connected in series successively between control power source voltage Vcc and earth level.Connected node between the 12nd resistance 182 and the 13rd resistance 184, be connected with the connected node between the drain electrode of the drain electrode of the 3rd switch element 202 and the 4th switch element 204.Connected node between the drain electrode of the drain electrode of the 3rd switch element 202 and the 4th switch element 204, be connected with the non-reversion input terminal of comparator 164.Reversion input terminal to comparator 164 applies voltage drop Vm.

Non-inversion output terminal of comparator 164 is connected with gate drivers 166.The phase place of the signal that gate drivers 166 makes the phase place of back segment control signal S2 occur with the sub-place of the non-inversion output terminal at comparator 164 is consistent.That is,, if the signal that the non-inversion output terminal place of comparator 164 occurs is high level (low level), gate drivers 166 makes back segment control signal S2 become high level (low level).

The 2nd operational amplifier 162 and 1npn type bipolar transistor 190 using bucking voltage Voffset as input, the resistance value of output Voffset/(the 8th resistance 174) electric current.According to take the phase place of voltage drop Vm as the output of the comparator 164 of input, this electric current is poured into or pulled out to the dividing potential drop node between the 12nd resistance 182 and the 13rd resistance 184.The 3rd switch element 202 and the 4th switch element 204 for the electric bridge mode, the timing that is high level (the 2nd switch element 140 is connected) at the grid of the 2nd switch element 140, the 3rd switch element 202 is connected, the voltage of the dividing potential drop node between the 12nd resistance 182 and the 13rd resistance 184 rises, and sets upper current limit value Ith1.If drive current Iout rises and reaches upper current limit value Ith1,, when the grid with the 2nd switch element 140 becomes in fact low level (the 2nd switch element 140 disconnects), the 4th switch element 204 is connected.Thus, the lower voltage of the dividing potential drop node between the 12nd resistance 182 and the 13rd resistance 184, set floor level of electric current Ith2.

The mean value of drive current Iout is to be set by the branch pressure voltage between the 12nd resistance 182 and the 13rd resistance 184.In addition, due to the effect of hysteresis amplitude initialization circuit 138, if the absolute value of driving voltage Vout approaches voltage threshold Vth, fill with/draw electric current and become large, therefore, it is large that upper current limit value Ith1-floor level of electric current Ith2=hysteresis amplitude, ao I becomes.The absolute value of driving voltage Vout and voltage threshold Vth differ larger, and hysteresis amplitude, ao I is just less.As described later, this is that switching frequency for making down converter 104 drops in prescribed limit.

Return to Fig. 1, optical semiconductor source control device 100 is configured to, the control of can being lit a lamp separately to a N LED2-1 to 2-N/turn off the light.Bypass drive circuit 112 generates for N the light-off control signal Sc1～ScN that lights a lamp that lights a lamp/turn off the light and controlled to each LED2-1 to 2-N.Respectively the light a lamp level of light-off control signal Sc1 to ScN of 112 pairs of bypass drive circuits is controlled separately, to obtain desired brightness and light distribution patterns.Specifically, bypass drive circuit 112 is in the situation that light a lamp 1LED2-1, and the 1st light-off control signal Sc1 that lights a lamp is set to low level, in the situation that 1LED2-1 is turned off the light, the 1st light-off control signal Sc1 that lights a lamp is set to high level.For the 2nd light-off control signal Sc2 to the N light-off control signal ScN that lights a lamp that lights a lamp, arrange similarly.The bypass drive circuit 112 light-off control signal Sc1 to ScN that will respectively light a lamp exports to corresponding bypass circuit 270-1 to 270-N.

The 1st bypass circuit 270-1 to the N bypass circuit 270-N is connected in parallel with 1LED2-1 to the N LED2-N respectively.The 1st bypass circuit 270-1 to the N bypass circuit 270-N is connected in series successively between the high-side lead-out terminal of down converter 104 and low level side lead-out terminal.

The 1st bypass circuit 270-1 lights a lamp light-off control signal Sc1 while being high level the 1st, makes conducting between the two ends of 1LED2-1, that is, with the impedance lower than 1LED2-1, connected.Thus, 1LED2-1 turns off the light.Below, the state of the bypass circuit that the above-mentioned LED of making is turned off the light is called the bypass on-state.The 1st bypass circuit 270-1 lights a lamp light-off control signal Sc1 while being low level the 1st, makes with the impedance higher than 1LED2-1, to be connected between the two ends of 1LED2-1.Thus, 1LED2-1 lights a lamp.Below, the state of the bypass circuit that the above-mentioned LED of making is lit a lamp becomes the bypass off-state.

The 1st bypass circuit 270-1 generates the 1st anomaly detection signal Sdet1 extremely detected for the distribution to 1LED2-1 and periphery thereof, and supplies with to bypass drive circuit 112.In the situation that the 1st anomaly detection signal Sdet1 is high level, at the 1st bypass circuit 270-1 during in the bypass off-state, the voltage that is applied to the 1st bypass circuit 270-1 is compared low with short-circuit detecting voltage, or the height of comparing with the burn out detection voltage higher than short-circuit detecting voltage.Short-circuit detecting voltage is set as lower than the forward drop Vf of 1 LED.Burn out detection voltage is set as higher than the forward drop Vf of LED, and lower than the forward drop sum 2Vf of 2 LED.

The 2nd bypass circuit 270-2 to the N bypass circuit 270-N similarly, separately based on the 2nd light-off control signal Sc2 to the N light-off control signal ScN that lights a lamp that lights a lamp, controls the light a lamp/light-off state of 2LED2-2 to the N LED2-N.In addition, the 2nd bypass circuit 270-2 to the N bypass circuit 270-N generates respectively the 2nd anomaly detection signal Sdet2 to the N anomaly detection signal SdetN, to bypass drive circuit 112, supplies with.

Bypass drive circuit 112 is in the situation that make while usually lighting a lamp the brightness of 1LED2-1 reduce, and the 1st light-off control signal Sc1 that lights a lamp is periodically changed with the square wave shape with the dim light frequency f 1 from hundreds of Hz to several kHz.By this 1st pulse modulation of light-off control signal Sc1 of lighting a lamp, thereby 1LED2-1 is gone out with 1 of dim light frequency f, reduce the lightness that human eye is experienced.The 1st duty ratio of lighting a lamp light-off control signal Sc1 is set as accessing desired luminous degree.In the case, due to when 1LED2-1 lights a lamp, the larger variation of the drive current size that flows through 1LED2-1 is suppressed, institute so that colour cast be inhibited.For each 2LED2-2 to the N LED2-N, bypass drive circuit 112 has PWM(Pulse Width Modulation similarly) the dim light function.

Bypass drive circuit 112, based on the 1st anomaly detection signal Sdet1, judges whether the distribution of 1LED2-1 and periphery thereof has occurred extremely.If the 1st anomaly detection signal Sdet1 becomes high level, bypass drive circuit 112 is judged to be and has occurred extremely, forces to make the 1st light-off control signal Sc1 that lights a lamp to become high level.For example, according to PWM dim light function, should make the 1st to light a lamp during light-off control signal Sc1 is low level, the bypass drive circuit 112 light-off control signal Sc1 that will the 1st lights a lamp remains high level.In addition, if bypass drive circuit 112 is judged to be and has not occurred extremely, should make the 1st to light a lamp during light-off control signal Sc1 is low level, also make the 1st light-off control signal Sc1 that lights a lamp become high level.Bypass drive circuit 112 also has identical abnormal detection function for 2LED2-2 to the N LED2-N.

The 1st bypass is connected the 1st bypass side connected node NB1 between the 1st bypass circuit 270-1 and the 2nd bypass circuit 270-2 and the 1st load-side connected node NL1 between 1LED2-1 and 2LED2-2 with connecting distribution 280-1.In the situation that the 1st bypass circuit 270-1 in bypass off-state and the 2nd bypass circuit 270-2 in the bypass on-state, flow through the 1st bypass with the polarity of the drive current Iout that connects distribution 280-1 for from load-side to the bypass side towards.In the situation that the 1st bypass circuit 270-1 in bypass on-state and the 2nd bypass circuit 270-2 in the bypass off-state, flow through the 1st bypass with the polarity of the drive current Iout that connects distribution 280-1 for from bypass side loading side towards.Thus, flow through the polarity of the 1st bypass with the drive current Iout that connects distribution 280-1 in the former situation, with to flow through the 1st bypass in the latter's situation contrary by the polarity of the drive current Iout that connects distribution 280-1.

The 2nd bypass is with connecting distribution 280-2 to the (N-1) bypass with connecting distribution 280-(N-1) also identical.

Bypass drive circuit 112 and the 1st bypass circuit 270-1 to the N bypass circuit 270-N are configured to, in the situation that bypass, with the connection distribution, poor flow has occurred, will be set to the bypass on-state with 2 the two pressures of bypass circuit that are connected the distribution connection with this bypass.

Fig. 5 means the circuit diagram of the structure of the 2nd bypass circuit 270-2 and the 3rd bypass circuit 270-3.The 2nd bypass circuit 270-2 comprises level shifting circuit 254-2 for the 2nd switch, 2nd bypass/pressure limiting circuit 250-2, the 2nd break detection circuit 272-2, the 2nd short-circuit detecting circuit 274-2, level shifting circuit 276-2 and the 2nd integrating circuit 278-2 for the 2nd detection signal.

The 2nd switch receives the 2nd light-off control signal Sc2 that lights a lamp with level shifting circuit 254-2 from bypass drive circuit 112, and it is transformed to and take the cathode voltage of 2LED2-2 low level the 2nd by-pass switch drives signal Sd2 as benchmark is made as.The 2nd by-pass switch drives the light a lamp phase place of light-off control signal Sc2 of the phase place and the 2nd of signal Sd2 consistent, and the low level of the 2nd by-pass switch driving signal Sd2 becomes the cathode voltage of 2LED2-2.Like this, the 2nd switch carries out level conversion with level shifting circuit 254-2 to the 2nd light-off control signal Sc2 that lights a lamp, and supplies with to 2nd bypass of correspondence/pressure limiting circuit 250-2.

2nd bypass/pressure limiting circuit 250-2 comprises the 2nd by-pass switch 110-2 be connected in parallel with 2LED2-2.2nd bypass/pressure limiting circuit 250-2, in the situation that the 2nd by-pass switch driving signal Sd2 is high level (low level), makes 2LED2-2 light-off (lighting a lamp) by making the 2nd by-pass switch 110-2 connect (disconnection).In addition, 2nd bypass/pressure limiting circuit 250-2 is configured to, and when the 2nd by-pass switch drives signal Sd2 to be low level, uses the 2nd by-pass switch 110-2, limits the upper limit of the both end voltage of the 2nd by-pass switch 110-2.

2nd bypass/pressure limiting circuit 250-2 comprises pressure limiting Zener diode 256, counterflow-preventing diode 258, the 16th resistance 260 and the 2nd by-pass switch 110-2.The 2nd by-pass switch 110-2 for example consists of N passage MOSFET.

The negative pole of pressure limiting Zener diode 256 is connected with the drain electrode of the 2nd by-pass switch 110-2.Their connected node connects with being connected distribution 280-1 with the 1st bypass.The positive pole of pressure limiting Zener diode 256 is connected with the positive pole of counterflow-preventing diode 258.The grid of the 2nd by-pass switch 110-2 has the 2nd by-pass switch to drive signal Sd2 via the 16th resistance 260 inputs.The source electrode of the 2nd by-pass switch 110-2 connects with being connected distribution 280-2 with the 2nd bypass.

Drive signal Sd2 by the 2nd by-pass switch for making the 2nd by-pass switch 110-2 on/off, the gate electrode side of the 2nd by-pass switch 110-2 is connected with the series circuit of pressure limiting Zener diode 256 and counterflow-preventing diode 258.That is, the negative pole of counterflow-preventing diode 258 is connected between the grid of the 16th resistance 260 and the 2nd by-pass switch 110-2.

When the threshold voltage of the grid of Vf=0.5V, the 2nd by-pass switch 110-2 of the Zener voltage=6V of pressure limiting Zener diode 256, counterflow-preventing diode 258=2.5V, if the both end voltage of the 2nd by-pass switch 110-2 drains, voltage between one source pole reaches 9V, the 2nd by-pass switch 110-2 starts to connect, therefore, the higher limit of the both end voltage of the 2nd by-pass switch 110-2 is that burn out detection voltage is 9V.

The Zener voltage of pressure limiting Zener diode 256 is set as; make the burn out detection voltage height of comparing with the maximum of the Vf of 2LED2-2; and it is low with the Zener voltage by the 2nd electrostatic protection Zener diode 252-2 regulation, to compare, and compares low with the Vf of 2LED2-2 and the Vf sum of 3LED2-3.For example, in the situation that each LED has identical in fact characteristic, when the Zener voltage of maximum=6V, the 2nd electrostatic protection Zener diode 252-2 of the Vf of LED=20V, the Zener voltage of pressure limiting Zener diode 256 is set as the scope of 3V to 9V.

Counterflow-preventing diode 258 is for avoiding hindering the on/off that drives the 2nd by-pass switch 110-2 of signal Sd2 based on the 2nd by-pass switch.For example, when the 2LED2-2 that makes to be connected in parallel turns off the light or forces to make the 2nd by-pass switch 110-2 to connect as the measure of broken string described later or loose contact, if there is no counterflow-preventing diode 258, the grid voltage of the 2nd by-pass switch 110-2, from the forward of pressure limiting Zener diode 256, can reduce via the 2nd by-pass switch 110-2 in on-state.Counterflow-preventing diode 258 prevents above-mentioned condition.

When the 2nd break detection circuit 272-2 disconnects (being nonconducting state) at the 2nd by-pass switch 110-2, whether judgement, on the path by the drive current Iout of 2LED2-2, poor flow occurs.When the 2nd short-circuit detecting circuit 274-2 disconnects at the 2nd by-pass switch 110-2, judge whether 2LED2-2 or wiring closet are short-circuited extremely.In the situation that detect extremely in the 2nd break detection circuit 272-2 or the 2nd short-circuit detecting circuit 274-2, via the 2nd detection signal, with level shifting circuit 276-2, the integrating condenser 282 of the 2nd integrating circuit 278-2 is charged with the 1st time constant.It is that low level and detecting in the 2nd break detection circuit 272-2 or the 2nd short-circuit detecting circuit 274-2 during abnormal continues that this charging drives signal Sd2 at the 2nd by-pass switch.During in addition, integrating condenser 282 is discharged with the 2nd time constant longer than the 1st time constant.

The 2nd detection signal has the 17th resistance the 284, the 18th resistance 286 and 4pnp type bipolar transistor 288 with level shifting circuit 276-2.One end of the 17th resistance 284 is connected with the emitter of 4pnp type bipolar transistor 288.Connected node place at them applies the control power source voltage Vcc.The other end of the 17th resistance 284 is connected with an end of the 18th resistance 286.Their connected node is connected with the base stage of 4pnp type bipolar transistor 288.

The 2nd break detection circuit 272-2 has the 23rd resistance 210 and 6npn type bipolar transistor 212.The collector electrode of 6npn type bipolar transistor 212 is connected with the other end of the 18th resistance 286.The base stage of 6npn type bipolar transistor 212 is connected with the connected node of the positive pole of counterflow-preventing diode 258 with the positive pole of pressure limiting Zener diode 256 via the 23rd resistance 210.The emitter of 6npn type bipolar transistor 212 connects with being connected distribution 280-2 with the 2nd bypass.

The 2nd short-circuit detecting circuit 274-2 has the 19th resistance the 290, the 20th resistance the 292, the 21st resistance the 294, the 22nd resistance 296,4npn type bipolar transistor 298 and 5npn type bipolar transistor 208.The 20th resistance 292 and the 22nd resistance 296 are connected in series with connecting between distribution 280-2 with connecting distribution 280-1 and the 2nd bypass in the 1st bypass successively.The connected node of the 20th resistance 292 and the 22nd resistance 296 is connected with an end of the 21st resistance 294 and the base stage of 4npn type bipolar transistor 298.The other end of the 21st resistance 294 is connected with the negative pole of counterflow-preventing diode 258.The emitter of 4npn type bipolar transistor 298 connects with being connected distribution 280-2 with the 2nd bypass.The collector electrode of 4npn type bipolar transistor 298 is connected with an end of the 19th resistance 290.The other end at the 19th resistance 290 applies the control power source voltage Vcc.The collector electrode of 4npn type bipolar transistor 298 is connected with the base stage of 5npn type bipolar transistor 208 with the connected node of the 19th resistance 290.The emitter of 5npn type bipolar transistor 208 connects with being connected distribution 280-2 with the 2nd bypass, and collector electrode is connected with the other end of the 18th resistance 286.

The 2nd integrating circuit 278-2 has integrating condenser 282, the 24th resistance 214 and the 25th resistance 216.The earth level ground connection of one end of the 24th resistance 214 to equate in fact with the earth level of microcomputer, the other end is connected with an end of the 25th resistance 216.The connected node of the 24th resistance 214 and the 25th resistance 216 is connected with the collector electrode of 4pnp type bipolar transistor 288.The other end of the 25th resistance 216 is connected with an end of integrating condenser 282.The earth level ground connection of the other end of integrating condenser 282 to equate in fact with the earth level of microcomputer.The voltage of one end of integrating condenser 282 is supplied with to bypass drive circuit 112 as the 2nd anomaly detection signal Sdet2.

In the situation that on the path of drive current Iout, poor flow has occurred, at the off period of the 2nd by-pass switch 110-2, the both end voltage of the 2nd by-pass switch 110-2 rises and surpasses forward drop Vf.If its both end voltage surpasses burn out detection voltage, current flowing in pressure limiting Zener diode 256.Thus, the 6npn type bipolar transistor 212 of the 2nd break detection circuit 272-2 is connected.

In addition, in the situation that short circuit has occurred 2LED2-2, at the off period of the 2nd by-pass switch 110-2, the both end voltage of the 2nd by-pass switch 110-2 is lower than forward drop Vf.If its both end voltage is lower than short-circuit detecting voltage, the 4npn type bipolar transistor 298 of the 2nd short-circuit detecting circuit 274-2 disconnects, and 5npn type bipolar transistor 208 is connected.

Be set as the 20th resistance the 292, the 21st resistance 294 and the 22nd resistance 296 resistance value separately and meet following 3 conditions.

(1), when the other end of the 21st resistance 294 is applied with high level, 4npn type bipolar transistor 298 is connected.

(2), when the both end voltage that is applied with low level and the 2nd by-pass switch 110-2 at the other end of the 21st resistance 294 is more than or equal to short-circuit detecting voltage, 4npn type bipolar transistor 298 is connected.

(3), when the both end voltage that is applied with low level and the 2nd by-pass switch 110-2 at the other end of the 21st resistance 294 is less than short-circuit detecting voltage, 4npn type bipolar transistor 298 disconnects.

If one of them of 6npn type bipolar transistor 212 or 5npn type bipolar transistor 208 connected, the 2nd detection signal is connected with the 4pnp type bipolar transistor 288 of level shifting circuit 276-2.Control power source voltage Vcc for take the positive voltage that the earth level of microcomputer is benchmark.In the situation that detect extremely in the 2nd break detection circuit 272-2 or the 2nd short-circuit detecting circuit 274-2, to the 2nd integrating circuit 278-2, supply with to control power source voltage Vcc.Charging to integrating condenser 282 is carried out via the 25th resistance 216, and electric discharge is carried out via the 24th resistance 214 and the 25th resistance 216.Be greater than the resistance value of the 25th resistance 216 by the resistance value that is set as making the 24th resistance 214, even thereby at the average current 10% (connection of the 2nd by-pass switch 110-2=90% of lighting a lamp, disconnect=10%) this for during abnormality detection (, the off period of the 2nd by-pass switch 110-2), during shorter dim light, also can detect abnormal.

The 3rd bypass circuit 270-3 and the 2nd bypass circuit 270-2 form in the same manner, comprise the 3rd switch level shifting circuit 254-3 corresponding with level shifting circuit 254-2 with the 2nd switch, with 3rd bypass that 2nd bypass/pressure limiting circuit 250-2 is corresponding/pressure limiting circuit 250-3, the 3rd break detection circuit 272-3 corresponding with the 2nd break detection circuit 272-2, the 3rd short-circuit detecting circuit 274-3 corresponding with the 2nd short-circuit detecting circuit 274-2, the 3rd detection signal level shifting circuit 276-3 corresponding with level shifting circuit 276-2 with the 2nd detection signal, and the 3rd integrating circuit 278-3 corresponding with the 2nd integrating circuit 278-2.

Each the 1st bypass circuit 270-1, the 4th bypass circuit 270-4 to the N bypass circuit 270-N also form in the same manner with the 2nd bypass circuit 270-2.

Action to the optical semiconductor source control device 100 of said structure describes.

Fig. 6 (a) to (c) means the curve chart that the time of drive current Iout changes.Consider at first to make 1 LED light a lamp, then make only about half of lighting a lamp, then the situation that whole LED are lit a lamp.Do not consider the PWM dim light here.The time of drive current Iout when Fig. 6 (a) means to make 1 LED light a lamp, make a remaining N-1 LED to turn off the light by corresponding by-pass switch is connected changes.The time of drive current Iout when Fig. 6 (b) means to make the only about half of N/2 of a being LED light a lamp, make residue to turn off the light changes.The time of drive current Iout when Fig. 6 (c) means whole LED are lit a lamp changes.

, illustrate hysteresis amplitude, ao I is regulated in (c) at Fig. 6 (a), with light a lamp number, light-off number regardless of LED, the switching frequency that all makes the 2nd switch element 140 is the situation of switch periods Ts constant.But, for the those skilled in the art that read this specification, in the present embodiment known, so long as the mode suppressed with the variation of the switch periods Ts that causes of variations of light a lamp number, light-off number to by LED is controlled and is got final product hysteresis amplitude, ao I.

With reference to Fig. 6 (a), in the situation that the LED negligible amounts of lighting a lamp, during the turn-on time of the 2nd switch element 140 Ton, drive current Iout rises quickly, and during the opening time of the 2nd switch element 140 Toff, drive current Iout descends more slowly.Hysteresis magnitudes table now is shown to Δ I1.The absolute value of driving voltage Vout is lower, and the bucking voltage Voffset generated by hysteresis amplitude initialization circuit 138 is also lower.

With reference to Fig. 6 (b), in the situation that the LED quantity of the LED quantity of lighting a lamp and light-off is roughly the same, driving voltage Vout become flyback adjuster 102 setting voltage half the left and right, the 2nd switch element 140 turn-on time Ton with opening time Toff identical.The overall variation speed of drive current Iout is compared increase with the situation of the LED negligible amounts of lighting a lamp.

Hysteresis amplitude initialization circuit 138 as shown in Figure 3, generates higher bucking voltage Voffset.Down converter drive circuit 136 receives higher bucking voltage Voffset, and the hysteresis amplitude, ao I1 that the number of lighting a lamp of make to lag behind amplitude, ao I2 and LED is 1 o'clock compares increase.Thus, the recruitment of the overall variation speed of drive current Iout is cancelled, and switch periods Ts keeps constant.

With reference to Fig. 6 (c), in the situation that the LED negligible amounts of turning off the light or do not have, during the turn-on time of the 2nd switch element 140 Ton, drive current Iout rises more slowly, during the opening time of the 2nd switch element 140 Toff, drive current Iout descends quickly.With the situation that the number of lighting a lamp of LED equates with the light-off number, compare, the overall variation speed of drive current Iout reduces.The absolute value of driving voltage Vout is higher, and the bucking voltage Voffset generated by hysteresis amplitude initialization circuit 138 is lower.

Down converter drive circuit 136 receives lower bucking voltage Voffset, and the hysteresis amplitude, ao I2 in the situations that the amplitude, ao I3 that makes to lag behind equates with the light-off number with the number of lighting a lamp of LED compares and diminishes.Thus, the decrease of the overall variation speed of drive current Iout is cancelled, and switch periods Ts keeps constant.

The 2nd by-pass switch when Fig. 7 means the PWM dim light drives the sequential chart of the variation of signal Sd2 and the 2nd anomaly detection signal Sdet2.The 2nd by-pass switch herein drives signal Sd2 to light a lamp corresponding with average current 20%.That is, the 2nd by-pass switch drive signal Sd2 be length T off during low level be become high level during length T on about 1/4th.

In the situation that do not occur any extremely, no matter the 2nd by-pass switch drives signal Sd2 how to change, and the 2nd anomaly detection signal Sdet2 all constant earth level that remains microcomputer is near 0V.Here, suppose the 2nd by-pass switch drive signal Sd2 become high level during in the moment t1 poor flow or broken string occur.At moment t1, because the 2nd by-pass switch drives signal Sd2, be high level, the 2nd by-pass switch 110-2 connects (being conducting state), thus 6npn type bipolar transistor 212 and 5npn type bipolar transistor 208 the two all remain open.Thus, the level of the 2nd anomaly detection signal Sdet2 does not change in fact.

At the 2nd by-pass switch, drive signal Sd2 to be converted to low level moment t2 from high level, due to abnormal one of them connection that causes 6npn type bipolar transistor 212 or 5npn type bipolar transistor 208 occurred, start to integrating condenser 282 chargings.

The 2nd by-pass switch drive signal Sd2 become low level during in moment t3, integrating condenser 282 is full of electricity.The voltage of the 2nd anomaly detection signal Sdet2 when integrating condenser 282 is full of electricity is higher than the level threshold Vg for the level of determining the 2nd anomaly detection signal Sdet2 in bypass drive circuit 112.

Drive at the 2nd by-pass switch the moment t4 that signal Sd2 is high level from low transition, the two all disconnects 6npn type bipolar transistor 212 and 5npn type bipolar transistor 208, and integrating condenser 282 starts electric discharge.

After moment t3, the 2nd anomaly detection signal Sdet2 is higher than level threshold Vg, but because microcomputer is that the responsiveness of bypass drive circuit 112 is slower, so, temporarily continue to carry out the level conversion that the 2nd by-pass switch drives signal Sd2.

Drive on signal Sd2 and once from high level, be converted to low level moment t5 at the 2nd by-pass switch, in the situation that generation is abnormal still lasting, start again to charge to integrating condenser 282.Then, integrating condenser 282 is full of electricity again.

In addition, due to related the 2nd time constant of the electric discharge that is set as integrating condenser 282 1st time constant related with the charging length of comparing, so, even the moment t4 that drives signal Sd2 to become high level at the 2nd by-pass switch is to during t5 constantly, the voltage of the 2nd anomaly detection signal Sdet2 also remains higher than level threshold Vg.Like this, after the 2nd by-pass switch drives signal Sd2 to repeat several times level conversion, it is high level from low transition that bypass drive circuit 112 is judged to be the 2nd anomaly detection signal Sdet2.

In addition, in Fig. 7, be illustrated for integrating condenser 282 being reached in during once disconnecting at the 2nd by-pass switch 110-2 to be full of electric situation, but be not limited thereto, can be also while repeating off period, integrating condenser 282 approaches and is full of electricity at every turn.

To connecting distribution 280-1 to the (N-1) bypass for the 1st bypass with connecting distribution 280-(N-1) the situation of one of them generation poor flow under the action of optical semiconductor source control device 100 describe.As an example, consider, in the situation that poor flow occurs in connecting distribution 280-2 for the 2nd bypass, the situation of poor flow occurs in the position of " X " mark shown in the label 218 of the circuit shown in Fig. 5.

In the situation that poor flow occurs, the electrical level rising of the connected node of the drain electrode of the source electrode of the 2nd by-pass switch 110-2 and the 3rd by-pass switch 110-3 with in connecting distribution 280-2 in the 2nd bypass.When the 2nd by-pass switch 110-2 and the two disconnection of the 3rd by-pass switch 110-3, because the characteristic of the 2nd by-pass switch 110-2 and the 3rd by-pass switch 110-3 is poor etc., the level of this connected node approaches the level of the drain electrode of the level of source electrode of the 2nd by-pass switch 110-2 or the 3rd by-pass switch 110-3.And, for example, if the level of this connected node fully approaches the level of the drain electrode of the 3rd by-pass switch 110-3, by the 3rd short-circuit detecting circuit 274-3, be judged to be that short circuit has occurred is abnormal.The 3rd anomaly detection signal Sdet3 becomes high level, and bypass drive circuit 112 makes the 3rd light-off control signal Sc3 that lights a lamp be fixed as high level.

Like this, the 3rd by-pass switch 110-3 connects, and the both end voltage of the 2nd by-pass switch 110-2 becomes in fact 2Vf.Lower than 2Vf, so the 2nd break detection circuit 272-2 is judged to be, poor flow has occurred due to burn out detection voltage.The 2nd anomaly detection signal Sdet2 becomes high level, and bypass drive circuit 112 makes the 2nd light-off control signal Sc2 that lights a lamp be fixed as high level.

Its result, the two forces the 2nd by-pass switch 110-2 and the 3rd by-pass switch 110-3 to connect, and the two is maintained the light-off state 2LED2-2 and 3LED2-3.

In addition, in the situation that the level of the connected node of the drain electrode of the source electrode of the 2nd by-pass switch 110-2 and the 3rd by-pass switch 110-3 approaches the level of the source electrode of the 2nd by-pass switch 110-2, it is abnormal that the 2nd short-circuit detecting circuit 274-2 detects short circuit, it is abnormal that the 3rd break detection circuit 272-3 detects broken string, still the 2nd by-pass switch 110-2 and the two pressure of the 3rd by-pass switch 110-3 connected.

Were it not for and take to make 2 by-pass switches to force the measure of connecting, but will for the 2nd by-pass switch that 2LED2-2 is lit a lamp, drive signal Sd2 to be made as low level, and will drive signal Sd3 to be made as in the situation of high level for making the 3rd by-pass switch that 3LED2-3 turns off the light, although the 3rd by-pass switch 110-3 connects, but drive current Iout does not flow through the 3rd by-pass switch 110-3, but flows through 3LED2-3.That is, can't make 3LED2-3 turn off the light.Make the 2nd by-pass switch drive signal Sd2 to become high level, the 3rd by-pass switch drives signal Sd3 to become in low level situation, although the 2nd by-pass switch 110-2 connects, drive current Iout does not flow through the 2nd by-pass switch 110-2, but flows through 2LED2-2.That is, can't make 2LED2-2 turn off the light.

As implied above, in the situation that the 2nd bypass, with in connecting distribution 280-2, poor flow occurs, be difficult to control separately 2LED2-2,3LED2-3 light a lamp/light-off state separately.

In present embodiment in related optical semiconductor source control device 100, in the situation that the 1st bypass is with connecting distribution 280-1 to the (N-1) bypass with connecting distribution 280-(N-1) one of them poor flow occurs, the bypass that makes to occur poor flow is forced connections with connecting 2 by-pass switches that distribution connects.Thus, 2 LED that bypass connected with the connection distribution turn off the light.

In the situation that bypass, with in connecting distribution, poor flow occurs, as noted above, 2 LED light a lamp/light-off state separately that is difficult to individually this bypass be connected with the connection distribution is controlled.For example, consider the driving beam of optical semiconductor source control device 100 for headlight for automobile, there is optical semiconductor source control device 100 and make relevant LED turn off the light can not cause to preceding vehicle or opposite vehicle the situation of the function of dazzle.In the case, if the bypass connected to relevant LED, with connecting distribution generation poor flow, can't make relevant LED turn off the light and may cause dazzle.Therefore, in the present embodiment, if poor flow occurs with connecting in distribution in bypass, by pressure, connected 2 by-pass switches are connected, thereby can make to occur the bypass use connection distribution of poor flow and the bypass path of drive current Iout, it doesn't matter, maintains the light-off state of relevant LED.Thus, can avoid causing dazzle.

In addition, the related optical semiconductor source control device 100 of present embodiment has PWM dim light function, and it is by making by-pass switch be regulated the brightness of corresponding LED with higher speed on/off.This by-pass switch is when connecting, and the both end voltage of by-pass switch approaches 0V, but can not to be judged as short circuit abnormal because this is not abnormal.Therefore, optical semiconductor source control device 100 is configured to, and does not carry out short circuit abnormality detection and broken string abnormality detection when by-pass switch is connected, and when by-pass switch disconnects, it is detected.

Thus, in the situation that the LED in the PWM dim light or distribution abnormal, need to disconnect and occur extremely and no matter have or not the abnormal accessory conduction pathway switch all to connect this two states extremely judging in alternately at a high speed at by-pass switch.As to the lighting a lamp/turn off the light and main equipment that PWM dim light function is controlled of LED, mostly use microcomputer.Usually, because microcomputer is moved with the long period interval of the degree of a few tens of milliseconds, so and only be not suitable at high speed to a plurality of LED the situation that is extremely detected and judge separately.For example, in the situation that dim light frequency f 1 for several kHz, average electric current 10% and light a lamp, the length of the off period of by-pass switch is the hundreds of Microsecond grade.This shorter during in judge and need to adopt responsiveness high price microcomputer faster when abnormal/normal.

Therefore, in present embodiment in related optical semiconductor source control device 100, no matter whether the effect by integrating circuit generates carries out the PWM dim light and is all high level when abnormal, is low level anomaly detection signal when normal.Microcomputer be bypass drive circuit 112 based on this anomaly detection signal, judge normal/abnormal.Thus, in the situation that adopt to use the PWM dim light function of by-pass switch, do not adopt the microcomputer of high price can extremely being detected LED or distribution yet.

In addition, the related optical semiconductor source control device 100 according to present embodiment, even in the situation that come in contact the poor flows such as bad or broken string on the path of drive current Iout, also can be suppressed being applied to the rising of voltage on by-pass switch.For example; consideration, when 1LED2-1 lights a lamp state the 1st by-pass switch 110-1 disconnects, the distribution of the upstream side of the connected node of the negative pole of the positive pole of 1LED2-1 and the 1st electrostatic protection Zener diode 252-1, is that the distribution place of " X " mark shown in the label 262 of the circuit shown in Fig. 1 comes in contact situation bad or broken string.

If above-mentioned loose contact or broken string occur, the both end voltage of the 1st by-pass switch rises, and the 1st anomaly detection signal Sdet1 is high level from low transition.Carry out above-mentioned conversion if bypass drive circuit 112 detects the 1st anomaly detection signal Sdet1, be judged to be 1LED2-1 and occurred extremely, in circuit shown in Fig. 1, take to make the 1st by-pass switch 110-1 to connect and the measure that can make other LED light a lamp.

But, due to as noted above, microcomputer is that the responsiveness of bypass drive circuit 112 is slower, therefore, this measure needs the time of a few tens of milliseconds to the hundreds of millisecond usually.Here, in the situation that the optical semiconductor source control device does not have the related pressure-limiting function of present embodiment, due to the capacitor that does not have the level and smooth use of output voltage, cause after above-mentioned loose contact or broken string have just occurred a few kV(absolute values that the energy that output is accumulated in inductor 144 and the parasitic capacity of the 1st by-pass switch determine) high voltage.Before the 1st by-pass switch is connected, above-mentioned high voltage is applied on the 1st by-pass switch.Thus, as the 1st by-pass switch, no matter whether only apply a few V voltage when usually lighting a lamp, all need to consider loose contact or broken string and select the element of anti-a few kV voltages.

On the other hand, the related optical semiconductor source control device 100 with pressure-limiting function according to present embodiment, when above-mentioned broken string or loose contact generation, although the drain electrode of the 1st by-pass switch 110-1-voltage between source electrodes is risen, effect that can be by pressure limiting Zener diode 256 and the 1st by-pass switch 110-1 itself is limited the rising of this voltage.Thus, even consider loose contact or broken string, as the 1st by-pass switch 110-1, also can select low withstand voltage element.

Here, when broken string or loose contact generation, as an example, the 1st by-pass switch 110-1 has acted on a few tens of milliseconds to the hundreds of millisecond with 10V * 1A=10W left and right, but less owing to originally connecting resistance, need to use to a certain degree larger equipment, so less on the impact of equipment size or cost.

For example; consideration for the state of lighting a lamp when the 1st by-pass switch 110-1 disconnects, the distribution in the downstream of the connected node of the negative pole of the positive pole of 1LED2-1 and the 1st electrostatic protection Zener diode 252-1, is that the distribution of " X " mark shown in the label 264 of circuit shown in Fig. 1 comes in contact situation bad or broken string at 1LED2-1.In the situation that the optical semiconductor source control device does not have the related pressure-limiting function of present embodiment, the energy that inductor 144 is accumulated is most consumed by the 1st electrostatic protection Zener diode.Thus, as the 1st electrostatic protection Zener diode, need to select to bear the above-mentioned element consumed than macro-energy.Perhaps; as the 1st electrostatic protection Zener diode, also can consider to adopt to there is the element that issuable a few kV voltage while occurring with loose contact or broken string is compared higher Zener voltage, but usually; if Zener voltage is so high, can't realize the function of electrostatic protection originally.

On the other hand; the related optical semiconductor source control device 100 with pressure-limiting function according to present embodiment, the higher limit that is set as the both end voltage of the 1st by-pass switch 110-1 is compared low with the Zener voltage of the 1st electrostatic protection Zener diode 252-1 defined.Thus, as the 1st electrostatic protection Zener diode 252-1, can select less Zener diode.

In the situation that one of them of 2LED2-2 to the N LED2-N identical loose contact or broken string occurs also in the same manner, the upper limit of the voltage that applies on corresponding by-pass switch or electrostatic protection Zener diode is limited.Thus, as corresponding by-pass switch, low withstand voltage element can be adopted, in addition, as corresponding electrostatic protection Zener diode, less Zener diode can be adopted.

In addition, in present embodiment in related optical semiconductor source control device 100, for controlling the by-pass switch of lighting a lamp/turning off the light of LED, also as working for the switch of the pressure-limiting function of the both end voltage of LED for realizing.That is, by-pass switch works as light a lamp/turn off the light control function and pressure-limiting function simultaneously.Thus, can be when control function and pressure-limiting function to be lit a lamp/are turned off the light in realization, suppression element quantity increases.

In present embodiment in related optical semiconductor source control device 100, because the deferent segment of the LED2-1 to 2-N at N does not arrange the capacitor of level and smooth use, so drive current Iout is more excellent with respect to the tracing ability of the 2nd switch element 140.Especially, if the 2nd switch element 140 disconnects, drive current Iout diminishes, if the 2nd switch element 140 is connected, drive current Iout becomes large.And, in order to make near drive current Iout stabilisation desired value, replace smoothing and adopt the hysteresis of drive current Iout to control.Its result, can make the response high speed in current feedback.For example, can be in the effect due to bypass drive circuit 112 and by-pass switch and the number of lighting a lamp of LED while changing, make drive current Iout follow quickly the variation of above-mentioned load.Drive current Iout when the number of lighting a lamp that especially, can suppress LED increases owes punching and the overshoot of the drive current Iout of the number of lighting a lamp while reducing.

In addition, in present embodiment, in related optical semiconductor source control device 100, the flyback adjuster 102 of leading portion is made as negative pole output, and the down converter 104 of back segment also is made as negative pole output.Thus, as by-pass switch, can adopt the N passage MOSFET that characteristic is more excellent.

On the basis of negative pole output, because inductor 144 is not to be arranged between the negative pole and output of fly-wheel diode 142, and be arranged between positive pole and output, therefore, as the 2nd switch element 140 of down converter 104, can adopt the N passage MOSFET that characteristic is more excellent.In addition, can stably detect driving voltage Vout.

In addition, in the situation that the optical semiconductor source control device is anodal output, mostly considers the situation of LED ground connection and carry out the detection of drive current in high side.Here, if load variations, the level of detection position also changes, and therefore, is difficult to detect drive current accurately.In addition, the structure of testing circuit also likely becomes more complicated.Therefore, adopt negative pole output in related optical semiconductor source control device 100 in present embodiment, the output that is the ground connection side at side of the positive electrode arranges current sense resistor 108.Thus, even load (driving voltage Vout) changes, this changes the impact of the level of the detection position of drive current Iout also less, can stably detect drive current Iout.In addition, also can simplify the structure of testing circuit.

When drive current Iout being lagged behind to control, if the input voltage of down converter 104 or driving voltage Vout or the two change, the slope variation of the rising of drive current Iout or decline, therefore, likely make the switching frequency of the 2nd switch element 140 change.Therefore, in present embodiment in related optical semiconductor source control device 100, with the mode control lag amplitude, ao I of the variation that suppresses switching frequency.Especially, by setting, make the target switch frequency avoid the frequency band of known radio noise, thereby can suppress the harmful effect of radio noise to semiconductor light source control device 100.

In addition, in present embodiment in related optical semiconductor source control device 100, the effect by flyback adjuster 102 suppresses the variation of the input voltage of the down converter 104 that the variation due to battery tension Vbat causes.Thus, can suppress to cause due to the variation of the input voltage of down converter 104 variation of switching frequency.In other words, because hysteresis amplitude, ao I is selected in the combination of the input voltage without according to down converter 104 and driving voltage Vout, but can mainly based on driving voltage Vout, select hysteresis amplitude, ao I, therefore, can further simplify the control for hysteresis amplitude, ao I is regulated.This also contributes to small-scale, the high speed of control circuit.

In addition, in present embodiment in related optical semiconductor source control device 100, at the deferent segment of flyback adjuster 102, be provided with output capacitor 128.When by-pass switch is connected, if the 2nd switch element 140 connection, the disposable LED of flowing through of electric charge accumulated in this output capacitor 128.But, be provided with inductor 144 on the path due to the drive current Iout at optical semiconductor source control device 100, therefore, can make the mobile smoothing of above-mentioned electric charge, suppress the overshoot of drive current Iout.When bypass switch opens, also suppress in the same manner the punching of owing of drive current Iout.

Consideration is for the overshoot of the drive current Iout that suppresses by-pass switch when switching or owe punching and the related semiconductor light sources lamp circuit 300 of following Comparative Examples of design in addition.

Fig. 8 means the circuit diagram of the structure of the semiconductor light sources lamp circuit 300 that Comparative Examples is related.Semiconductor light sources lamp circuit 300 is the front fed inverter that does not use smmothing capacitor basically.Semiconductor light sources lamp circuit 300 has control circuit 302, input capacitor 306, reset circuit 308, transformer 310, the 5th switch element the 312, the 2nd diode the 314, the 3rd diode 316, inductor 318 and current sense resistor 320.

If the size of drive current surpasses the upper current limit value of regulation, control circuit 302 disconnects the 5th switch element 312, if the size of drive current lower than floor level of electric current, is connected the 5th switch element 312.

For optical semiconductor lamp circuit 300, if the ratio of winding of transformer 310 is made as to Ns/p, the inductance of inductor 318 is made as Ls ', and the hysteresis amplitude of drive current is made as Δ I ', and input voltage is made as Vin, output voltage is made as Vout(<0), be made as Ton ' turn-on time of the 5th switch element 312, be made as Toff ' its opening time, and switching frequency is made as F ', and, because the forward drop of rectifier diode is less and it is ignored, F ' can obtain by following formula.

In semiconductor light sources lamp circuit 300, be transformed to output=100V at will input=6V of the ratio of winding=16.7(of transformer 310), when the inductance of inductor 318=500 μ H, hysteresis amplitude=0.1A, the relation between the Vin obtained by formula 1, Vout, F ' is as described in Table 1., suppose input voltage change=6V to 20V here, output (load) variation in voltage=-4V is to the LED of 22 Vf=4V of-88V(series connection).

In the case, maximum/minimum change of switching frequency F ' is about 17 times.Although can be suppressed this amplitude of variation by inductance is increased, this can cause circuit to maximize.In addition, in the situation that realize carrying out computing and the larger variation of this switching frequency F ' being suppressed to the function in prescribed limit according to input voltage and output voltage, it is large that the control circuit scale becomes.

The related optical semiconductor source control device 100 for present embodiment, also carry out identical calculating.For optical semiconductor source control device 100, if the inductance of inductor 144 is made as to Ls, switching frequency is made as F, and, because the forward drop of fly-wheel diode 142 is less and it is ignored, F can obtain by following formula.

In optical semiconductor source control device 100, when the inductance of target voltage Vt=-100V, inductor 144=500 μ H, hysteresis amplitude=0.1A, between the Vt obtained by formula 2, Vout, F, relation as described in Table 2.

In the case, the variation of switching frequency F suppresses for about 6.5 times.In addition, the major parameter that causes this variation is driving voltage Vout, and target voltage Vt fixes in fact, and therefore, the scale of control circuit of variation that can make hysteresis amplitude, ao I is regulated to suppress switching frequency F is less.

Observe the calculated value of the switching frequency F of table 2,, along with driving voltage Vout descends from-4V to-44V, switching frequency F rises, and along with driving voltage Vout descends from-44V to-88V, switching frequency F reduces.The only about half of of the output voltage of the flyback adjuster 102 that the border of the rising of switching frequency F/reduction is the 1st section (leading portion) (input voltage of the down converter 104 of the 2nd section (back segment)) is-50V.Thus, by so that driving voltage Vout Vout>-lower hysteresis amplitude, ao I is larger during 50V, Vout<-lower less mode is controlled during 50V, thereby can easily switching frequency F be limited in prescribed limit.

In addition, in the present embodiment, the output voltage that the border of observing the rising of switching frequency F/reduction is flyback adjuster 102 only about half of, but, in other execution mode with other Circnit Layout, also should consider the situation that this border is 1/3rd or four of output voltage/first-class.In short, between the maximum and minimum value of Vout, may there is the peaked Vout that applies switching frequency F when the hysteresis constant amplitude.Thus, if by experiment or simulation etc. find out this Vout so that the mode forming circuit of hysteresis amplitude, ao I minimum when this Vout can more suitably suppress the variation of switching frequency F.

The related optical semiconductor source control device 100 for present embodiment, the setting example of parameter is shown in following table 3.

Table 3

Vout(V)	Voffset	Lower voltage limit	Upper voltage limit	Ith2	Ith1	Average current	Switching frequency
								-4	0.25	0.2356	0.2456	1.178	1.228	1.203	382.2kHz
-8	0.37	0.2332	0.2480	1.166	1.240	1.203	498.7kHz
								-12	0.48	0.2309	0.2503	1.154	1.252	1.203	542.3kHz
-16	0.60	0.2285	0.2527	1.143	1.264	1.203	555.8kHz
								-20	0.72	0.2262	0.2551	1.131	1.275	1.203	553.7kHz
-24	0.83	0.2238	0.2574	1.119	1.287	1.203	542.8kHz
								-28	0.95	0.2215	0.2598	1.107	1.299	1.203	526.1kHz
-32	1.07	0.2191	0.2621	1.095	1.311	1.203	505.7kHz
								-36	1.18	0.2167	0.2645	1.084	1.322	1.203	482.6kHz
-40	1.30	0.2144	0.2668	1.072	1.334	1.203	457.6kHz
								-44	1.42	0.2120	0.2692	1.060	1.346	1.203	431.0kHz
-48	1.54	0.2097	0.2716	1.048	1.358	1.203	403.4kHz
								-52	1.56	0.2093	0.2720	1.046	1.360	1.203	398.2kHz
-56	1.46	0.2113	0.2700	1.056	1.350	1.203	419.6kHz
								-60	1.36	0.2132	0.2680	1.066	1.340	1.203	438.2kHz
-64	1.26	0.2152	0.2660	1.076	1.330	1.203	453.4kHz
								-68	1.16	0.2172	0.2640	1.086	1.320	1.203	464.4kHz
-72	1.06	0.2192	0.2621	1.096	1.310	1.203	469.9kHz
								-76	0.97	0.2211	0.2601	1.106	1.300	1.203	468.4kHz
-80	0.87	0.2231	0.2581	1.116	1.291	1.203	457.3kHz
								-84	0.77	0.2251	0.2561	1.125	1.281	1.203	433.1kHz
-88	0.67	0.2271	0.2542	1.135	1.271	1.203	390.0kHz

Voffset forms, and the circuit constant of the hysteresis amplitude initialization circuit 138 shown in Fig. 2 is regulated, thereby, near Vout=-50V, shown in curve chart as shown in Figure 3, magnitude of voltage uprises.Lower voltage limit/upper voltage limit is the voltage of the dividing potential drop node of the 12nd resistance 182 of the down converter drive circuit 136 shown in Fig. 4 and the 13rd resistance 184, corresponds respectively to floor level of electric current Ith2, upper current limit value Ith1.Lower voltage limit/upper voltage limit is each resistance value by setting the 8th resistance the 174, the 12nd resistance the 182, the 13rd resistance 184 and controls power source voltage Vcc, calculates according to bucking voltage Voffset.Average current is the mean value of upper current limit value Ith1 and floor level of electric current 1th2.Switching frequency is in the formula identical with formula 2, and △ I=Ith1 mono-Ith2, Vt=mono-100V, gs=200 μ H are obtained.

Even known Ls is decreased to 200 μ H from 500 μ H, also can makes switching frequency drop on and be slightly larger than 550kHz to the scope that is slightly less than 400kHz.That is, the related optical semiconductor source control device 100 according to present embodiment, can be used in the inductance miniaturization of drive current Iout smoothing.

In addition, semiconductor light sources lamp circuit 300 and the related optical semiconductor source control device 100 of present embodiment that Comparative Examples is related compare, the output capacitor 128 of flyback adjuster 102 and the 2nd switch element 140 of down converter 104 have been increased in optical semiconductor source control device 100, but owing to removing reset circuit 308 from semiconductor light sources lamp circuit 300, so circuit scale is roughly the same.

Above, structure and the action of the optical semiconductor source control device that execution mode is related have been described.This execution mode is only illustration, and those skilled in the art should be clear, and above-mentioned each inscape or each treatment combination can form various variation, and these variation also belong to scope of the present invention.

In execution mode, arrangements of components as down converter 104, for respectively the 2nd switch element 140 being arranged on to the negative side of fly-wheel diode 142, the situation that inductor 144 is arranged on to the side of the positive electrode of fly-wheel diode 142 is illustrated, but is not limited to this.Fly-wheel diode is as long as be connected in parallel with the output capacitor 128 of flyback adjuster 102.As long as the 2nd switch element is arranged on from an end of output capacitor 128 to LED and return the path of drive current Iout of the other end of output capacitor 128 from LED, and is arranged between output capacitor 128 and fly-wheel diode and gets final product.The on/off of the 2nd switch element also can be controlled based on drive current.As long as inductor 144 is arranged on the path of drive current Iout, and is arranged between fly-wheel diode and LED and gets final product.

Fig. 9 (a) to (c) is the circuit diagram that the structure of the related optical semiconductor source control device 400,500,600 of the 1st, the 2nd and the 3rd variation is shown.Fig. 9 (a) means the structure of the optical semiconductor source control device 400 that the 1st variation is related.One end of the 2nd switch element 440 is connected with the output of the high-side of flyback adjuster 102, and the other end is connected with the negative pole of fly-wheel diode 442.One end of inductor 444 is connected with the connected node of the negative pole of fly-wheel diode 442 with the other end of the 2nd switch element 440.The other end ground connection of inductor 444, and become the high-side lead-out terminal of LED.The positive pole of fly-wheel diode 442 is connected with the low level side output of flyback adjuster 102, and becomes the low level side lead-out terminal of LED.

Fig. 9 (b) means the structure of the optical semiconductor source control device 500 that the 2nd variation is related.The negative pole of fly-wheel diode 542 is connected and ground connection with the high-side output of flyback adjuster 102, forms the high-side output of LED.One end of the 2nd switch element 540 is connected with the output of the low level side of flyback adjuster 102, and the other end is connected with the positive pole of fly-wheel diode 542.One end of inductor 544 is connected with the connected node of the positive pole of fly-wheel diode 542 with the other end of the 2nd switch element 540.The other end of inductor 544 becomes the low level side lead-out terminal of LED.

Fig. 9 (c) means the structure of the optical semiconductor source control device 600 that the 3rd variation is related.One end of the 2nd switch element 640 is connected with the output of the low level side of flyback adjuster 102, and the other end is connected with the positive pole of fly-wheel diode 642.The connected node of the positive pole of the other end of the 2nd switch element 640 and fly-wheel diode 642, form the low level side output of LED.The negative pole of fly-wheel diode 642 is connected with an end of inductor 644.The connected node of one end of the negative pole of fly-wheel diode 642 and inductor 644 is connected with the output of the high-side of flyback adjuster 102.The other end ground connection of inductor 644, and become the high-side lead-out terminal of LED.

Related each semiconductor light source control device 400,500,600 according to the 1st, the 2nd and the 3rd variation, with the related optical semiconductor source control device 100 of execution mode in the same manner, can reduce the overshoot of drive current Iout and owe punching.

In execution mode, the side of the positive electrode ground connection that is a plurality of LED for the high-side by making output realizes that the situation of negative pole output is illustrated, but be not limited to this, such as also the side of the positive electrode of a plurality of LED being connected with the terminal that battery tension Vbat etc. applies direct voltage.

In execution mode, the situation of forming circuit in the following manner has been described,, the real time measure switching frequency not, but replace, the known relation based between driving voltage Vout and switching frequency, determine the relation between driving voltage Vout and hysteresis amplitude, ao I, so that hysteresis amplitude, ao I changes based on this relation, but be not limited to this.For example, also can make the semiconductor light sources control device there is the circuit that the switching frequency of the 2nd switch element 140 is measured, the hysteresis amplitude is regulated so that the switching frequency of this mensuration drops on the frequency range of hope.

In execution mode, the situation that comprises N by-pass switch 110-1 to 110-N for optical semiconductor source control device 100 is illustrated, but is not limited to this, also by-pass switch can be arranged separately outside the optical semiconductor source control device.

In execution mode, situation about controlling for the hysteresis of carrying out drive current is illustrated, but be not limited to this, for example also can be controlled the duty ratio of the 2nd switch element 140, so that voltage drop Vm is carried out to suitable filtered voltage, approach the reference voltage corresponding with target current.

In execution mode, following situation has been described, that is, by combination flyback adjuster 102 and down converter 104, form drive circuit, this drive circuit generates drive current Iout, the size of exercising this drive current Iout of going forward side by side approaches the control of desired value, but be not limited to this, for example, as this drive circuit, also can use the circuit shown in Fig. 8, perhaps, also can adopt the flyback adjuster that carries out Current Feedback Control.

Figure 10 means the circuit diagram of the structure of optical semiconductor source control device 700 that the 4th variation is related and connected parts.Optical semiconductor source control device 700 has flyback adjuster 702, current sense resistor 708, a N bypass circuit 270-1 to 270-N and bypass drive circuit 112.

In this variation in related optical semiconductor source control device 700, in the situation that poor flow occurs with the position of " X " sign shown in the label 718 that connects distribution 280-2 in the 2nd bypass, with the related optical semiconductor source control device 100 of present embodiment in the same manner, by the effect of the 2nd bypass circuit 270-2, the 3rd bypass circuit 270-3 and bypass drive circuit 112, force to connect the 2nd by-pass switch and the 3rd by-pass switch the two.

In addition, the limits value of the maximum voltage of flyback adjuster 702 output, consider to be connected in series N the situation that all LED light a lamp and to be set as being more than or equal to the Vf sum.For example, in the maximum of the Vf by 1 LED, be made as 6V, and while being connected in series 30 LED, limits value is set as being more than or equal to 180V.Here, the distribution indicated at " X " shown in the label 762 of Figure 10 comes in contact moment bad or broken string, owing to not flowing through drive current Iout in LED, so the output voltage of flyback adjuster 702 rises to 180V.Control circuit (not shown) is no longer mobile if drive current Iout detected, checks which distribution or LED break, and in the circuit of Figure 10, takes to connect the 1st by-pass switch 110-1 and measure that other LED can be lit a lamp.This measure needs the time of a few tens of milliseconds to the hundreds of millisecond usually.

Here, in the situation that the optical semiconductor source control device does not have pressure limiting Zener diode 256 and counterflow-preventing diode 258, before the 1st by-pass switch is connected, the output voltage of flyback adjuster 702 arrives 180V.Now, if (under room temperature) mean value of the Vf of the LED used is 4V, electric current is 3V while flowing hardly, and the 1st by-pass switch is applied with the voltage of 180V-3V * 30=90V.Thus, for any one in 30 by-pass switches, no matter whether only apply the voltage of common several V, all must consider broken string or loose contact and select the element of the voltage of anti-100V.

Below; in the distribution of " X " if shown in the label of Figure 10 764 sign, short-term or loose contact occur; the 1st electrostatic protection Zener diode is applied in above-mentioned 90V when current flowing hardly, is applied in 180V-4V * 30=60V flowing through while controlling electric current.Here; if the Zener voltage of the 1st electrostatic protection Zener diode is made as to 20V; due to 90V or the 60V voltage higher than 20V; so in the time controlling electric current and be made as 1A; in a few tens of milliseconds to during the hundreds of millisecond; the 1st electrostatic protection Zener diode effect has 20V * 1A=20W, needs to select to bear the element of this power.For fear of above-mentioned situation, as long as make the Zener voltage of the 1st electrostatic protection Zener diode be more than or equal to 90V, but just be difficult to like this effect of realization electrostatic protection originally.

Therefore, the related optical semiconductor source control device 700 of this variation is by having 1st bypass/pressure limiting circuit 250-1, thereby, even come in contact bad or broken string, also can be suppressed at the upper limit of the voltage applied on the 1st by-pass switch 110-1.Thus, as the 1st by-pass switch 110-1 without selecting the anti-element that is more than or equal to the high pressure of 100V.In addition, be set as being less than or equal to the Zener voltage of the 1st electrostatic protection Zener diode 252-1 by the deboost that 1st bypass/pressure limiting circuit 250-1 is produced, can select less Zener diode.

In addition, at execution mode in related optical semiconductor source control device 100, due in the situation that do not there is pressure-limiting function, need to make by-pass switch bear the kV step voltage, so more remarkable in execution mode by the withstand voltage inhibition that pressure-limiting function produces is set.

In execution mode, LED and by-pass switch situation one to one has been described, but has been not limited to this, also can utilize a by-pass switch to control lighting a lamp/turning off the light of a plurality of LED.For example, in the situation that connect 2 LED, connect a by-pass switch, total maximum=12V of the Vf of LED, the Zener voltage=40V of electrostatic protection Zener diode, thus, as long as the Zener voltage of pressure limiting Zener diode is dropped in the scope of 9V to 21V.When the Zener voltage by the pressure limiting Zener diode is made as 20V, the limits value of both end voltage is 23V, therefore, needs only the element of selecting the voltage of anti-30V as by-pass switch.

In execution mode, be not only the 2nd bypass with connecting distribution 280-2, even in the situation that the 3rd bypass with the label 220(that connects distribution 280-3 with reference to Fig. 5) shown in the position of " X " mark poor flow occurs, also, by the effect of the 2nd bypass circuit 270-2, the 3rd bypass circuit 270-3, the 4th bypass circuit 270-4 and bypass drive circuit 112, the 2nd by-pass switch, the 3rd by-pass switch and the 4th by-pass switch are all forced to connect.

In execution mode, following situation has been described,, in the situation that poor flow occurs with in connecting distribution in bypass, with this bypass with is connected 2 by-pass switches that distribution connects which because broken string is forced connection extremely, due to short circuit, extremely to force connection be to depend on the characteristic of by-pass switch etc. to carry out for which, but be not limited to this.The bypass circuit that can be also for example, odd number to sequence number (the 1st bypass circuit 270-1, the 3rd bypass circuit 270-3 ...) resistance is set respectively in parallel.The bypass circuit that can be also even number to sequence number in addition, arranges respectively resistance in parallel.In the case, in the situation that bypass, with in connecting distribution, poor flow occurs, an above-mentioned side by-pass switch that is provided with resistance is forced to connect according to short circuit extremely, the above-mentioned side by-pass switch that resistance is not set is forced to connect according to broken string extremely.

In execution mode, the burn out detection function of using bypass circuit and bypass drive circuit and function of short circuit detection are tackled to bypass and be illustrated by the situation of the poor flow of connection distribution, but be not limited to this.For example, also can bypass with in connecting distribution, arrange current measuring unit etc. for detection of bypass the unit with the poor flow that connects distribution, use this unit to judge that bypass is with in the connection distribution, whether poor flow occurring.Also can make the bypass drive circuit in the situation that be judged to be the generation poor flow, force to make 2 corresponding by-pass switches to be connected.

In execution mode, following situation has been described, that is, in the situation that by-pass switch poor flow detected while disconnecting or short circuit is abnormal, make the integrating condenser charging, in the situation that in addition, make the integrating condenser electric discharge, but be not limited to this.For example, also can integrating condenser be discharged with the 1st time constant in the situation that by-pass switch poor flow detected while disconnecting or short circuit is abnormal, in the situation that in addition, integrating condenser be charged with the 2nd time constant.

In related optical semiconductor source control device 100, adopt PWM dim light function at execution mode.When the PWM dim light, bypass drive circuit 112 make the to light a lamp voltage level of light-off control signal periodically changes with dim light frequency f 1.In the situation that do not occur any extremely, when the light-off control signal of lighting a lamp is low level, corresponding by-pass switch is disconnected, when the light-off control signal of lighting a lamp is high level, corresponding by-pass switch is connected.Thus, the low level of the light-off control signal of lighting a lamp is to disconnect corresponding state with corresponding by-pass switch, and the high level of the light-off control signal of lighting a lamp is to connect corresponding state with corresponding by-pass switch.

In addition, bypass drive circuit 112 is microcomputers, is moved with the longer time interval.Especially, bypass drive circuit 112 is for each LED, during the abnormality juding of whole regulation in to anomaly detection signal monitored and determine whether occurred abnormal.And bypass drive circuit 112 in the situation that be judged to be certain LED and occurred extremely, makes the light a lamp light-off control signal corresponding with this LED be fixed as high level.If describe with determine/uncertain abnormal concept, if the time detecting of bypass drive circuit 112 during having continued abnormality juding goes out abnormality, be defined as extremely being made the connection locking of by-pass switch to control.

Due to longer than the cycle of PWM dim light (=l/f1) during common abnormality juding, so at execution mode in related optical semiconductor source control device 100, by importing integrating circuit, even can be when carrying out the PWM dim light, also can carry out the less and more accurate short circuit of error detection abnormal/the broken string abnormality detection.

Consideration at the LED that does not carry out the PWM dim light, light a lamp all the time (by-pass switch=all the time disconnect) the abnormal situation that breaks has occurred in controlling.During till having implemented to the by-pass switch corresponding with this LED to connect locking control from some LED generation broken strings, by the bypass/pressure limiting circuit corresponding with this LED, the particularly effect of pressure limiting Zener diode, by-pass switch is moved as the switch for realizing pressure-limiting function.Thus, can be maintained until the path of the electric current of other LED.But in the case, because by-pass switch is moved basically in the range of linearity, so this by-pass switch continuous action has the power of " burn out detection voltage * drive current Iout ", the power loss in by-pass switch increases.Thus, as by-pass switch, need switch element large-scale and that anti-power is larger, cause the maximization of circuit and cost to rise.Here, if at once by-pass switch is connected to locking control after abnormal detecting broken string, reduce power loss, but cause like this judgement number of times in bypass drive circuit 112 tail off (judgement time shorten), in PWM dim light pattern, the possibility of error detection broken string abnormal (malfunction) becomes large especially.

In addition, even in the situation that broken string has occurred while carrying out the PWM dim light, while also due to the light-off control signal of lighting a lamp, being low level, by-pass switch is moved as the switch for realizing pressure-limiting function, so equally likely make the power loss in by-pass switch increase.The ratio of (during the light-off of=LED) during the connection of by-pass switch shared in 1 cycle (=l/f1) of PWM dim light is called to the connection duty ratio.It is less that this connects duty ratio, and the above-mentioned power loss that broken string causes is larger.

In addition, when by-pass switch is connected, the power loss in by-pass switch is owing to being mainly to be produced and less by the connection resistance of by-pass switch, particularly with in the situation that the power loss of moving in the range of linearity is compared, circuit loss is very little.

Figure 11 means the circuit diagram of structure of the 2nd bypass circuit 870-2 of the optical semiconductor source control device that the 5th variation is related.Other bypass circuit and the 2nd bypass circuit 870-2 form in the same manner.

Difference between the 2nd bypass circuit 870-2 shown in the 2nd bypass circuit 270-2 shown in Fig. 5 and Figure 11 mainly is the structure of the 2nd switch with level shifting circuit.The 2nd switch level shifting circuit 854-2 of the 2nd bypass circuit 870-2, receive the 2nd light-off control signal Sc2' that lights a lamp from bypass drive circuit 812, it is transformed to the 2nd by-pass switch and drives signal Sd2.Especially, the 2nd switch is lit a lamp light-off control signal Sc2 ' when the high level with level shifting circuit 854-2 the 2nd, drive signal Sd2 to be set to low level the 2nd by-pass switch, the 2nd, light a lamp light-off control signal Sc2 ' during for low level, drive signal Sd2 to be set to high level the 2nd by-pass switch.

In addition, 2nd bypass of the 2nd bypass circuit 870-2/pressure limiting circuit 850-2 also can not have the resistance suitable with the 16th resistance 260.

The 2nd switch comprises the 26th resistance the 822, the 27th resistance the 814, the 28th resistance the 816, the 29th resistance 818 and 5pnp type bipolar transistor 820 with level shifting circuit 854-2.One end of the 26th resistance 822 is connected with the terminal of bypass drive circuit 812.Bypass drive circuit 812 from its terminal output the 2nd light-off control signal Sc2' that lights a lamp.The other end of the 26th resistance 822 is connected with the base stage of 5pnp type bipolar transistor 820.One end of the 27th resistance 814 is connected with the connected node of the base stage of 5pnp type bipolar transistor 820 with the other end of the 26th resistance 822.The emitter of the other end of the 27th resistance 814 and 5pnp type bipolar transistor 820 applies the control power source voltage Vcc.The collector electrode of 5pnp type bipolar transistor 820 is connected with an end of the 28th resistance 816.The other end of the 28th resistance 816 is connected with an end of the 29th resistance 818.The other end of the 29th resistance 818 is connected with the negative pole of 2LED2-2.

The connected node of the other end of the 28th resistance 816 and an end of the 29th resistance 818 is connected with the grid of the 2nd by-pass switch 110-2.The signal produced at this connected node place is that the 2nd by-pass switch drives signal Sd2.

Light a lamp light-off control signal Sc2 ' when the high level the 2nd, and it is low level that the 2nd by-pass switch drives signal Sd2, and the 2nd by-pass switch 110-2 disconnects (2LED2-2 lights a lamp).Light a lamp light-off control signal Sc2 ' when the low level the 2nd, and it is high level that the 2nd by-pass switch drives signal Sd2, and the 2nd by-pass switch 110-2 connects (2LED2-2 light-off).In the situation that carry out the PWM dim light, bypass drive circuit 812 makes the 2nd signal that light-off control signal Sc2 ' replaces for the high level/low level with several millisecond periods of lighting a lamp.

If the both end voltage of integrating condenser 282 surpasses the threshold voltage of regulation, bypass drive circuit 812 with light a lamp light-off control signal Sc2 ' synchronously, making to the control of the 2nd by-pass switch 110-2 is that when the cycle is compared increase with common PWM dim light for the connection duty of the signal that applies of grid with input terminal.Especially, if the voltage of the 2nd anomaly detection signal Sdet2 surpasses level threshold Vg, start during the abnormality juding that bypass drive circuit 812 makes for 2LED2-2, and the 2nd shared ratio low level duration the in 1 cycle of light-off control signal Sc2 ' of lighting a lamp is increased.As an example, made for the 2nd cycle of lighting a lamp light-off control signal Sc2 ' increase to the hundreds of millisecond, make to connect duty ratio and increase to and be more than or equal to 90%.

Figure 12 means in the situation that the light a lamp sequential chart of variation of light-off control signal Sc2, Sc2 ' of the 2nd of broken string occurs 2LED2-2.Waveform shown in the epimere of Figure 12, mean the optical semiconductor source control device that the 5th variation is related in the situation that carry out the 2nd of the PWM dim light light-off control signal Sc2 ' that lights a lamp with the 1st cycle PT1 of several milliseconds of left and right while usually lighting a lamp.Waveform shown in the stage casing of Figure 12, mean the related optical semiconductor source control device 100 of execution mode in the situation that the 2nd light-off control signal Sc2 that lights a lamp lit a lamp all the time while usually lighting a lamp.Waveform shown in the hypomere of Figure 12, mean the related optical semiconductor source control device 100 of execution mode in the situation that carry out the 2nd of the PWM dim light light-off control signal Sc2 that lights a lamp with the 1st cycle PT1 while usually lighting a lamp.

In the situation that in the 5th variation, broken string occurs 2LED2-2, the 2nd cycle of lighting a lamp light-off control signal Sc2' became the 2nd cycle PT2 of the hundreds of microsecond left and right of comparing large with the 1st cycle PT1.Especially, bypass drive circuit 812 maintain the 2nd high level of lighting a lamp in 1 cycle of light-off control signal Sc2 ' the duration length, and meanwhile make low level the duration elongated, thereby realize that the above-mentioned cycle becomes large.In addition, the 2nd cycle PT2 also can 2nd time constant related with the electric discharge of the 2nd integrating circuit 278-2 compare little.

In abnormality juding period P T3 about several seconds, if the 2nd lights a lamp the voltage of the 2nd anomaly detection signal Sdet2 of light-off control signal Sc2 ' while being set to high level higher than level threshold Vg, bypass drive circuit 812 and the 2nd is lit a lamp light-off control signal Sc2 ' synchronously, and when the cycle keeps the state that increases constant to the connection duty that makes to be applied to the signal on the grid of the 2nd by-pass switch 110-2.In the situation that the voltage of the 2nd anomaly detection signal Sdet2 is lower than level threshold Vg, bypass drive circuit 812 makes the 2nd light-off control signal Sc2' that lights a lamp recover to have the state of the 1st cycle PT1.Bypass drive circuit 812 at the voltage of the 2nd anomaly detection signal Sdet2 higher than the state of level threshold Vg in the situation that abnormality juding period P T3 is always lasting till finishing, be judged to be abnormal (determining abnormal) occurred, make the 2nd light-off control signal Sc2 ' that lights a lamp be fixed as low level.

In execution mode, in the situation that broken string occurs 2LED2-2, during abnormality juding period P T3, make the 2nd to light a lamp the state of light-off control signal Sc2 with abnormal that front state occurs is identical.And, if be judged to be when abnormality juding period P T3 finishes, occurred extremely, the 2nd light-off control signal Sc2 that lights a lamp is fixed as to high level.

Like this, the related optical semiconductor source control device according to the 5th variation, the optical semiconductor source control device 100 related with execution mode compared, even when lighting a lamp all the time or during the PWM dim light, and the total length of the off period of the by-pass switch in also can reducing during abnormality juding.Corresponding during while occurring with broken string due to this off period, by-pass switch is moved with the range of linearity, so, according to the 5th variation, can reduce the power loss in by-pass switch.Thus, as by-pass switch, anti-lower powered switch element can be adopted, miniaturization, the cost degradation of circuit can be realized.

Especially, in the situation owing to carrying out the PWM dim light, be unsuitable for just being judged to be and having occurred under abnormal situation at once in the level conversion of anomaly-based detection signal, according to the 5th variation, by carry out the supervision of anomaly detection signal during whole abnormality juding, can determine whether more accurately abnormal, and, the power loss of the by-pass switch in can reducing during abnormality juding.

Claims

1. a light source control device is characterized in that having:

Drive circuit, the drive current of a plurality of semiconductor light sources that are connected in series is flow through in its generation;

The 1st by-pass switch, the part in itself and described a plurality of semiconductor light sources is connected in parallel; And

The 2nd by-pass switch, itself and described the 1st by-pass switch are connected in series, and are connected in parallel with the another part in described a plurality of semiconductor light sources,

This light source control device is configured to,

For the connected node by between described the 1st by-pass switch and described the 2nd by-pass switch, the connection distribution that is connected with a part in described a plurality of semiconductor light sources and the connected node between the another part in described a plurality of semiconductor light sources, described the 1st by-pass switch disconnection and described the 2nd by-pass switch flow through the polarity of the electric current of described connection distribution while connecting, with described the 1st by-pass switch, connect and described the 2nd by-pass switch to flow through the polarity of electric current of described connection distribution while disconnecting contrary

In the situation that described connection distribution generation poor flow makes described the 1st by-pass switch and described the 2nd the two connection of by-pass switch forcibly.

2. light source control device according to claim 1, is characterized in that,

Also there is ON-OFF control circuit, itself in the situation that the both end voltage of described 1st by-pass switch of described the 1st by-pass switch while disconnecting lower than the 1st voltage or higher than 2nd voltage higher than described the 1st voltage, make forcibly described the 1st by-pass switch connect, and, in the situation that the both end voltage of described 2nd by-pass switch of described the 2nd by-pass switch while disconnecting makes described the 2nd by-pass switch connect lower than the 3rd voltage or higher than the 4th voltage higher than described the 3rd voltage forcibly.

3. light source control device according to claim 2, is characterized in that,

Described a plurality of semiconductor light sources is a plurality of light-emitting diodes,

Described the 2nd voltage and described the 4th voltage are set as respectively, and the forward drop of stipulating with the part by described a plurality of semiconductor light sources and the forward drop sum of the regulation of the another part in described a plurality of semiconductor light sources are compared low.

4. according to the described light source control device of claim 2 or 3, it is characterized in that,

Described ON-OFF control circuit also comprises:

Main control circuit, it makes periodically on/off of described the 1st by-pass switch when usually lighting a lamp; And

The abnormality detection auxiliary circuit, itself in the situation that the both end voltage of described 1st by-pass switch of described the 1st by-pass switch while disconnecting lower than described the 1st voltage or higher than described the 2nd voltage, the amount of the electric charge that capacitor is kept with the 1st time constant to the 1st towards variation, in the situation that the amount of the electric charge that does not make described capacitor keep with described the 1st time constant to the described the 1st towards changing, the amount of the electric charge that described capacitor is kept with 2nd time constant longer than described the 1st time constant to the described the 1st the towards the opposite the 2nd towards variation

The both end voltage of described main control circuit based on described capacitor, determine whether and make forcibly described the 1st by-pass switch connect.

5. a light source control device, is characterized in that,

Have: drive circuit, the drive current of a plurality of semiconductor light sources that are connected in series is flow through in its generation;

By-pass switch, at least a portion in itself and described a plurality of semiconductor light sources is connected in parallel;

Main control circuit, it makes periodically on/off of described by-pass switch when usually lighting a lamp; And

The abnormality detection auxiliary circuit, itself in the situation that the both end voltage of the described by-pass switch of described by-pass switch while disconnecting lower than the 1st voltage or higher than described 2nd voltage higher than described the 1st voltage, the amount of the electric charge that capacitor is kept with the 1st time constant to the 1st towards variation, in the situation that the amount of the electric charge that does not make described capacitor keep with described the 1st time constant to the described the 1st towards changing, the amount of the electric charge that described capacitor is kept with 2nd time constant longer than described the 1st time constant to the described the 1st the towards the opposite the 2nd towards variation

The both end voltage of described main control circuit based on described capacitor, determine whether abnormal, in the situation that be judged to be, occurred extremely, makes forcibly described by-pass switch connect.

6. a light source control device, is characterized in that,

Have: drive circuit, the drive current of a plurality of semiconductor light sources that are connected in series is flow through in its generation; And

By-pass switch, at least a portion in itself and described a plurality of semiconductor light sources is connected in parallel, and by control signal, controls on/off,

Control signal is, when usually lighting a lamp, makes to connect corresponding state and disconnect corresponding period of state ground with described by-pass switch with described by-pass switch to repeat,

This light source control device also has:

Pressure limiting circuit, it is configured to, and in control signal, when with described by-pass switch, disconnecting corresponding state, uses described by-pass switch to be limited the upper limit of the both end voltage of at least a portion in described a plurality of semiconductor light sources;

The abnormality detection auxiliary circuit, when it is limited the upper limit of both end voltage at described pressure limiting circuit, the amount of the electric charge that capacitor is kept with the 1st time constant to the 1st towards variation, in the situation that the amount of the electric charge that does not make described capacitor keep with described the 1st time constant to the described the 1st towards changing, the amount of the electric charge that described capacitor is kept with 2nd time constant longer than described the 1st time constant to the described the 1st the towards the opposite the 2nd towards variation; And

Main control circuit, its will with described by-pass switch connect corresponding state the duration in 1 cycle in control signal shared ratio be called while connecting duty ratio, if the both end voltage of described capacitor reaches the threshold voltage of regulation, make the connection duty ratio of control signal increase

Described main control circuit by long whole abnormality juding of the cycle than control signal during in the both end voltage of described capacitor is monitored, thereby determine whether and occurred extremely, occurred extremely in the situation that be judged to be, the state of control signal has been fixed as to the state corresponding with the connection of described by-pass switch.

7. light source control device according to claim 6, is characterized in that,

If the both end voltage of described capacitor reaches described threshold voltage, described main control circuit increases the cycle of control signal.