WO2022091974A1

WO2022091974A1 - Vehicle lamp

Info

Publication number: WO2022091974A1
Application number: PCT/JP2021/039107
Authority: WO
Inventors: 光治眞野
Original assignee: 株式会社小糸製作所
Priority date: 2020-10-29
Filing date: 2021-10-22
Publication date: 2022-05-05
Also published as: JPWO2022091974A1

Abstract

In the present invention, a scanning light-source (200A) includes a semiconductor light-source (212) and scans the emission light (BM) of the semiconductor light-source (212) across the entire range of the light distribution horizontal-direction. A lighting circuit (300A), in synchronization with the scanning of the scanning light-source (200A), can modulate the light volume of the semiconductor light-source (212) at each scanning position to multiple levels by using pulse modulation.

Description

Vehicle lighting

This disclosure relates to lighting fixtures for vehicles used in automobiles and the like.

Vehicle lighting fixtures can generally switch between low beam and high beam. The low beam illuminates the vicinity of the own vehicle with a predetermined illuminance, and the light distribution rule is set so as not to give glare to the oncoming vehicle or the preceding vehicle, and is mainly used when traveling in an urban area. On the other hand, the high beam illuminates a wide area and a distant place in front with a relatively high illuminance, and is mainly used when traveling at high speed on a road where there are few oncoming vehicles and preceding vehicles. Therefore, although the high beam has better visibility by the driver than the low beam, there is a problem that glare is given to the driver and pedestrian of the vehicle existing in front of the vehicle.

In recent years, ADB (Adaptive Driving Beam) technology that dynamically and adaptively controls the light distribution pattern of high beams based on the surrounding conditions of the vehicle has been put into practical use. The ADB technique detects the presence or absence of a preceding vehicle, an oncoming vehicle, or a pedestrian in front of the vehicle, dims the area corresponding to the vehicle, and reduces glare given to the vehicle.

As a method for realizing the ADB function, a shutter method for controlling an actuator, a rotary method, an LED array method, etc. have been proposed. In the shutter method and the rotary method, the width of the light-off area (light-shielding area) can be continuously changed, but the number of light-off areas is limited to one. In the LED array method, it is possible to set a plurality of extinguishing areas, but the width of the extinguishing area is limited by the irradiation width of the LED chip, so that the extinguishing area is discrete.

The applicant has proposed a scanning method as an ADB method that can solve these problems (see Patent Documents 2 and 3). The scan method is to incident light on a rotating reflector (blade mirror), reflect the incident light at an angle according to the rotation position of the reflector, scan the reflected light in front of the vehicle, and turn on and off the light source. A desired light distribution pattern is formed in front of the vehicle by changing the light distribution pattern according to the rotation position of the vehicle.

In the scan method described in Patent Document 3, the light source is turned on and off (on and off) in a time-division manner while keeping the amount of drive current flowing through the light source constant during one scan. Therefore, it was easy to realize a glare-free function that shields a predetermined area from light, but the illuminance in the irradiation area was restricted to a substantially constant level.

Patent Document 4 discloses a specific method for forming a light distribution using a scan-type vehicle lamp. In this technique, a light distribution is formed by a multi-channel light source. Each of the multi-channel light sources is responsible for a part of the horizontal range, and the scan range of each light source is shifted horizontally while partially overlapping the scan range of the other light sources. There is. The amount of light of each light source is controlled by so-called DC dimming (analog dimming), and is variable in units of one scan due to the limitation of response speed. With this lamp, the illuminance at each scanning position can be controlled by combining multiple light sources on, off, and the amount of light, and it is now compatible with various light distribution patterns other than the glare-free function (for example, electronic swivel). There is.

Japanese Unexamined Patent Publication No. 2008-205357 Japanese Unexamined Patent Publication No. 2012-224317 Japanese Unexamined Patent Publication No. 2010-6109 Japanese Unexamined Patent Publication No. 2018-187979

1. 1. The technique of Patent Document 4 requires light sources and lighting circuits of many channels to form one light distribution, has a complicated structure, and also controls the light source to form a desired light distribution. It was complicated.

A certain aspect of the present disclosure has been made in view of the above problems, and one of its exemplary purposes is to provide a vehicle lamp capable of generating various light distribution patterns other than the glare-free function.

2. 2. When the completely same PWM signal (pulse dimming signal) is repeatedly generated for each scan and the light source is turned on and off, a vertical line perpendicular to the scan direction (depending on the combination of PWM frequency, scan frequency, and duty cycle) ( Vertical stripes) may be visible.

A certain aspect of the present disclosure has been made in view of the above problems, and one of its exemplary purposes is to provide a lamp capable of suppressing the occurrence of vertical stripes.

3. 3. A certain aspect of the present disclosure is made in such a situation, and one of its exemplary purposes is to provide a vehicle lamp capable of detecting an abnormality immediately after the start of lighting in a scanning lamp.

4. A certain aspect of the present disclosure is made in such a situation, and one of the exemplary purposes is to provide a vehicle lamp capable of reliable abnormality detection.

1. 1. The vehicle lighting fixture of one aspect of the present disclosure includes a semiconductor light source, a scanning light source that scans the emitted light of the semiconductor light source over the entire horizontal range of the light distribution, and each scanning in synchronization with the scanning of the scanning light source. It is provided with a lighting circuit capable of dimming the amount of light of a semiconductor light source at a position in multiple gradations by pulse modulation.

2. 2. The vehicle lighting fixture of one aspect of the present disclosure includes a semiconductor light source, and pulse-modulates the amount of light of the semiconductor light source at each scanning position in synchronization with the scanning of the scanning type light source that scans the emitted light of the semiconductor light source and the scanning type light source. It is equipped with a lighting circuit that can be dimmed with multiple gradations. The lighting circuit changes the phase of pulse modulation with each scan.

3. 3. The vehicle lighting fixture of one aspect of the present disclosure includes a semiconductor light source, controls a scanning light source that scans the emitted light of the semiconductor light source, and controls a drive current supplied to the semiconductor light source in synchronization with scanning of the scanning light source, and is a semiconductor. It is equipped with a constant current driver that controls the amount of light from the light source. The constant current driver is connected to a series switch provided in series with the semiconductor light source and a series connection circuit between the series switch and the semiconductor light source, and (i) outputs a constant current during the on period of the series switch, and (ii) the series switch. To the buck converter that stops the switching operation during the off period and maintains substantially the same output voltage as the previous on period, the driver circuit that drives the series switch based on the pulse dimming signal, and the output voltage of the buck converter. Originally, it is provided with an abnormality detection circuit for detecting an abnormality. Triggered by the ignition on, the constant current driver drives the semiconductor light source and performs initialization lighting that raises the output voltage of the buck converter to the specified voltage.

4. The vehicle lighting fixture of one aspect of the present disclosure includes a semiconductor light source, controls a scanning light source that scans the emitted light of the semiconductor light source, and controls a drive current supplied to the semiconductor light source in synchronization with scanning of the scanning light source, and is a semiconductor. It is equipped with a constant current driver that controls the amount of light from the light source. The constant current driver is connected to a series switch provided in series with the semiconductor light source and a series connection circuit between the series switch and the semiconductor light source, and (i) outputs a constant current during the ON period of the series switch, and (ii) the series switch. To the buck converter that stops the switching operation during the off period and maintains substantially the same output voltage as the previous on period, the driver circuit that drives the series switch based on the pulse dimming signal, and the output voltage of the buck converter. Based on this, the abnormality detection circuit that detects anomalies, the duty cycle of the pulse dimming signal, and the product of the lighting time are integrated to calculate the cumulative lighting time, and the abnormality is detected while the cumulative lighting time is lower than the predetermined threshold value. It is provided with a mask processing unit that masks abnormality detection by the circuit.

It should be noted that any combination of the above components and those in which the components and expressions of the present disclosure are mutually replaced between methods, devices, systems, etc. are also effective as aspects of the present disclosure.

According to a certain aspect of the present disclosure, an abnormality can be reliably detected.

It is a block diagram of the lamp for a vehicle which concerns on the comparative technique examined by the present inventors. It is a figure which shows the ringing waveform of the driving current of LED. It is a figure which shows the lighting fixture for a vehicle which concerns on Embodiment 1. FIG. 4 (a) and 4 (b) are diagrams illustrating the formation of glare-free light distribution by vehicle lamps. 5 (a) and 5 (b) are diagrams illustrating the formation of a partially dimmed light distribution by a vehicle lamp. 6 (a) and 6 (b) are diagrams illustrating an electronic swivel by a vehicle lamp. It is a figure which shows the lamp for a vehicle which concerns on the comparative technique. It is a figure explaining the light distribution formation by the lamp for vehicle which concerns on the comparative technique. It is a block diagram which shows the structural example of a lighting circuit. It is a circuit diagram which shows the structural example of the LED driver. FIG. 11A is a diagram showing current control by a series switch, and FIG. 11B is a diagram showing current control by a bypass switch. It is a circuit diagram which shows the structural example of the LED driver. It is a circuit diagram which shows another configuration example of the LED driver. It is a circuit diagram which shows the further structural example of the LED driver. It is a figure which shows the lighting fixture for a vehicle which concerns on Embodiment 2. It is a block diagram which shows the structural example of the lighting circuit of FIG. It is a figure which shows the lighting fixture for a vehicle which concerns on Embodiment 3. It is a block diagram of a vehicle lamp equipped with a short-circuit abnormality detection function. 19 (a) and 19 (b) are diagrams illustrating the operation of the vehicle lamp of FIG. It is a circuit diagram of the abnormality detection circuit which concerns on one Example. It is a figure which shows the IV characteristic of a semiconductor light source. It is a figure explaining the determination process 1 of an abnormality detection circuit. It is a figure explaining the determination process 2 of an abnormality detection circuit. It is a figure explaining the determination process 3 of an abnormality detection circuit. FIG. 25 is a block diagram of a vehicle lamp according to the embodiment. 26 (a) and 26 (b) are diagrams illustrating the operation of the mask processing unit. It is a block diagram of the mask processing part which concerns on the 1st processing example. It is a block diagram of the mask processing part which concerns on the 2nd processing example. It is a block diagram of the mask processing part which concerns on 3rd processing example. 30 (a) to 30 (c) are diagrams illustrating vertical stripes in a combination of scan-type light distribution formation and pulse dimming. It is a block diagram of the lamp for a vehicle which concerns on embodiment. 32 (a) to 32 (c) are views illustrating an example of the operation of a vehicle lamp. 33 (a) to 33 (c) are diagrams illustrating an example of the operation of a vehicle lamp. It is a block diagram which shows the structural example of the PWM signal generation part. FIG. 3 is an operation waveform diagram of the PWM signal generation unit of FIG. 34. It is operation waveform diagram of the PWM signal generation part which concerns on modification 1. FIG. It is a block diagram of the lighting equipment for a vehicle which supports the initialization lighting. FIG. 3 is an operation waveform diagram of the vehicle lamp of FIG. 37. It is an operation waveform diagram of the lamp for a vehicle which concerns on modification 2. FIG.

(Outline of Embodiment)
Some exemplary embodiments of the present disclosure will be outlined. This overview simplifies and describes some concepts of one or more embodiments for the purpose of basic understanding of embodiments, as a prelude to the detailed description described below, and is an invention or disclosure. It does not limit the size. Also, this overview is not a comprehensive overview of all possible embodiments and does not limit the essential components of the embodiments. For convenience, "one embodiment" may be used to refer to one embodiment (examples or modifications) or a plurality of embodiments (examples or modifications) disclosed herein.

1. 1. The vehicle lighting equipment according to the embodiment includes a semiconductor light source, a scanning light source that scans the emitted light of the semiconductor light source over the entire horizontal range of the light distribution, and each scanning position in synchronization with the scanning of the scanning light source. It is provided with a lighting circuit capable of dimming the light amount of the semiconductor light source in multiple gradations by pulse modulation.

According to this configuration, by adopting pulse modulation, the amount of light from the light source can be changed at high speed according to the scanning position within one scanning cycle. Therefore, as compared with DC dimming (analog dimming) in which the amount of light is constant within one scanning cycle, the variation of light distribution that can be formed by one light source increases. As a result, the number of light sources and lighting circuits can be reduced as compared with the conventional case, or control can be simplified.

"Pulse modulation" includes pulse width modulation (PWM), pulse frequency modulation (PFM), pulse density modulation (PDM), etc., and switches the drive current flowing through the light source at high speed to obtain the time average value of the drive current. It may include varying modulation schemes.

In addition to the semiconductor light source, the scanning type light source may further include a reflector that receives the emitted light of the semiconductor light source and scans the reflected light in front of the vehicle by repeating a predetermined periodic motion. The lighting circuit may generate a control waveform of pulse modulation in synchronization with the motion of the reflector, and may switch the drive current supplied to the semiconductor light source according to the control waveform.

The lighting circuit may include a series switch provided in series with the semiconductor light source and a constant current driver connected to the series connection circuit of the series switch and the semiconductor light source. The lighting circuit may switch the series switch in a duty cycle according to the scanning position.

In the prior art (Patent Document 4), two semiconductor light sources are connected in series, and a bypass switch is provided in parallel with each semiconductor light source. In this configuration, switching one bypass switch at a frequency sufficiently higher than the scanning frequency will affect the other semiconductor light source. On the other hand, by individually driving each semiconductor light source with a series switch, it is possible to eliminate the influence of driving one channel on other channels.

The constant current driver may include a switching converter and a converter controller that drives the switching converter so that the detected value of the output current of the switching converter approaches a predetermined target value.

2. 2. The vehicle lamp according to the embodiment includes a semiconductor light source, and the light amount of the semiconductor light source at each scanning position is pulse-modulated in synchronization with the scanning of the scanning light source and the scanning light source that scans the emitted light of the semiconductor light source. It is equipped with a lighting circuit that can be dimmed with multiple gradations. The lighting circuit changes the phase of pulse modulation with each scan.

Changing the phase of pulse modulation may include changing the start timing of the pulse cycle, changing the pulse generation position within the pulse cycle, and the like.

By changing the phase of pulse modulation for each scan, that is, the lighting timing and the extinguishing timing, the lighting portion and the extinguishing portion due to pulse modulation can be moved for each scan. As a result, vertical lines (vertical stripes) can be suppressed.

In one embodiment, the lighting circuit may shift the phase of pulse modulation by 180 ° for each scan.

In one embodiment, the lighting circuit may shift the phase of pulse modulation by 360 ° / N (N ≧ 3) for each scan.

In one embodiment, the lighting circuit is connected to a series switch provided in series with the semiconductor light source, a step-down converter having a constant current output connected to the series connection circuit of the series switch and the semiconductor light source, and a phase-down converter for each scan. It may be provided with a dimming signal generation unit that generates a pulse-modulated pulse dimming signal that shifts the current, and a driver circuit that drives a series switch based on the pulse dimming signal.

3. 3. The vehicle lighting equipment according to one embodiment includes a semiconductor light source, controls a scanning type light source that scans the emitted light of the semiconductor light source, and controls a drive current supplied to the semiconductor light source in synchronization with scanning of the scanning type light source, and controls the semiconductor light source. It is equipped with a constant current driver that controls the amount of light. The constant current driver is connected to a series switch provided in series with the semiconductor light source and a series connection circuit between the series switch and the semiconductor light source, and (i) outputs a constant current during the on period of the series switch, and (ii) the series switch. To the buck converter that stops the switching operation during the off period and maintains substantially the same output voltage as the previous on period, the driver circuit that drives the series switch based on the pulse dimming signal, and the output voltage of the buck converter. Originally, it is provided with an abnormality detection circuit for detecting an abnormality. Triggered by the ignition on, the constant current driver drives the semiconductor light source and performs initialization lighting that raises the output voltage of the buck converter to the specified voltage.

According to this configuration, the series switch cuts off the output current of the buck converter and switches the continuity at high speed, so it is not necessary to change the output voltage of the buck converter in steps. As a result, ringing of the drive current due to charging / discharging of the output capacitor can be suppressed, and dimming by high-speed pulse modulation of several kHz to several tens of kHz becomes possible.

Also, according to this configuration, when the lamp lighting command is received after the initialization lighting is completed, the output voltage of the buck converter has risen to the specified voltage, so the abnormality detection circuit can immediately start abnormality detection. can.

In one embodiment, the abnormality detection circuit may determine that the series switch is abnormal if the output voltage of the buck converter deviates from the normal range during the off period of the series switch.

In PWM dimming by the bypass switch, when a short-circuit failure that the bypass switch cannot be turned off occurs, the LED is turned off, which is a preferable state from the viewpoint of not giving glare. On the other hand, in pulse dimming by the series switch, when the series switch cannot be turned off or a short circuit occurs (generally called short circuit abnormality), a current flows through the semiconductor light source and glare occurs on the oncoming vehicle or the preceding vehicle. Will be given. According to the above configuration, the switching of the buck converter is stopped during the off period of the series switch. Therefore, when a short circuit error occurs in the series switch, the output of the buck converter is output by the path including the series switch with the short circuit error and the semiconductor light source. The charge is discharged and the output voltage drops. Therefore, by monitoring the output voltage of the buck converter during the off period of the series switch, a short circuit abnormality of the series switch can be detected.

In one embodiment, the constant current driver may drive the semiconductor light source with a brightness that cannot be visually recognized from the surroundings in the initialized lighting. As a result, the initialization lighting can be completed without being noticed by the surrounding people.

In one embodiment, the constant current driver may turn on the semiconductor light source with a brightness that can be visually recognized from the surroundings in the initialized lighting. As a result, the initialized lighting can be shown to the surrounding people as an effect.

In one embodiment, the vehicle lighting fixture may further include a leveling device that controls the optical axis of the scanning light source in the pitch direction. In the initialized lighting, the leveling device may lower the optical axis of the scanning light source.

In one embodiment, the constant current driver may reduce the duty cycle of the pulse dimming signal to 5% or less or the duty cycle to the minimum value in the initialized lighting.

In one embodiment, the scanning light source may include a plurality of semiconductor light sources. There are a plurality of constant current drivers corresponding to a plurality of semiconductor light sources, and the timing of turning on the plurality of pulse dimming signals supplied to the plurality of constant current drivers may be shifted. This prevents a plurality of semiconductor light sources from lighting at the same time and makes it difficult to see from the surroundings.

In one embodiment, the constant current driver may reduce the amount of drive current in the initialized lighting as compared with the normal lighting. This makes it difficult to see from the surroundings.

4. The vehicle lighting equipment according to one embodiment includes a semiconductor light source, controls a scanning type light source that scans the emitted light of the semiconductor light source, and controls a drive current supplied to the semiconductor light source in synchronization with scanning of the scanning type light source, and controls the semiconductor light source. It is equipped with a constant current driver that controls the amount of light. The constant current driver is connected to a series switch provided in series with the semiconductor light source and a series connection circuit between the series switch and the semiconductor light source, and (i) outputs a constant current during the ON period of the series switch, and (ii) the series switch. To the buck converter that stops the switching operation during the off period and maintains substantially the same output voltage as the previous on period, the driver circuit that drives the series switch based on the pulse dimming signal, and the output voltage of the buck converter. Based on this, the abnormality detection circuit that detects anomalies, the duty cycle of the pulse dimming signal, and the product of the lighting time are integrated to calculate the cumulative lighting time, and the abnormality is detected while the cumulative lighting time is lower than the predetermined threshold value. It is provided with a mask processing unit that masks abnormality detection by the circuit.

Immediately after the start of lighting, the output voltage of the buck converter is 0V, and it is impossible to detect an abnormality based on the output voltage. According to this configuration, by calculating the cumulative lighting time from the start of lighting in consideration of the duty cycle of pulse dimming, it is possible to accurately detect that the output voltage of the buck converter has risen to the specified voltage, and then it can be detected accurately. , Abnormality detection based on the output voltage is possible. Since the duty cycle is equivalent to the brightness (dimming rate), the process of integrating the product of the brightness of the semiconductor light source and the lighting time is also included in the scope of the present disclosure.

In one embodiment, the abnormality detection circuit may weight the lighting time with a coefficient corresponding to the power supply voltage and integrate the lighting time. When the rising speed of the output voltage of the buck converter depends on the power supply voltage, the lighting time is weighted by the power supply voltage and integrated, so that it can be accurately detected that the output voltage of the buck converter has risen to the specified voltage.

In one embodiment, the pulse dimming signal generation circuit that generates the pulse dimming signal and the mask processing unit may be mounted on the same microcontroller. Since the microcontroller that generates the pulse dimming signal knows the duty cycle of the pulse dimming signal, the configuration can be simplified by performing the mask processing by the software processing of the microcontroller.

(Embodiment)
Hereinafter, the present disclosure will be described with reference to the drawings based on the preferred embodiments. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and duplicate description thereof will be omitted as appropriate. Further, the embodiment is not limited to the disclosure but is an example, and all the features and combinations thereof described in the embodiment are not necessarily essential to the disclosure.

In the present specification, the "state in which the member A is connected to the member B" means that the member A and the member B are physically directly connected, and the member A and the member B are electrically connected to each other. It also includes cases of being indirectly connected via other members that do not substantially affect the connection state or impair the functions and effects performed by the combination thereof.

Similarly, "a state in which the member C is provided between the member A and the member B" means that the member A and the member C, or the member B and the member C are directly connected, and their electricity. It also includes cases of being indirectly connected via other members that do not substantially affect the connection state or impair the functions and effects performed by the combination thereof.

Further, in the present specification, the reference numerals attached to electric signals such as voltage signals and current signals, or circuit elements such as resistors and capacitors have their respective voltage values, current values, resistance values, and capacitance values as necessary. It shall be represented.

First, the comparison technique will be explained. FIG. 1 is a block diagram of a vehicle lamp 100R according to a comparative technique examined by the present inventors. The vehicle lamp 100R includes a scanning optical system 2, a plurality of LEDs 4_1 to 4_N, a plurality of LED drivers 10, and a light distribution controller 20. A plurality of LEDs 4_1 to 4_N are connected in series every two (or three) to form a plurality of M LED strings 6_1 to 6_M. The LED driver 10 is provided for each LED string 6. The reason why the two LEDs are connected in series is to reduce the number of LED drivers.

The LED driver 10_1 includes a constant current output buck converter 12 and a drive circuit 14 for bypass switches SW1 and SW2 and bypass switches SW1 and SW2 provided in parallel with LEDs 4_1 and 4_2. The LED drivers 10_1 to 10_M are similarly configured.

The scanning optical system 2 horizontally scans the emitted beams BM ₁ to BM _N of the plurality of LEDs 4_1 to 4_N on the virtual vertical screen 900 in front of the vehicle. By scanning the emitted beams BM ₁ to BM _N , individual light distribution patterns PTN ₁ to PTN _N are formed. A plurality of individual light distribution patterns PTN ₁ to PTN _N are formed in different ranges in the horizontal direction. By synthesizing a plurality of individual light distribution patterns PTN ₁ to PTN _N , a synthetic light distribution of the entire vehicle lamp 100R is formed.

Focus on one LED_i. When the corresponding bypass switch SWi is turned on for a certain period of time during scanning, no current is supplied to the LED4_i, so that the LED_i can be turned off. When an oncoming vehicle or a preceding vehicle (referred to as a vehicle in front) is present in front of the vehicle, the bypass switch SWi is turned on while the emitted beam of LED_i passes through the existing range of the vehicle in front. As a result, the existing range of the vehicle in front can be shielded from light.

The scanning frequency by the scanning optical system 2 needs to be set higher than 60 Hz so that the scanning is not perceived by the human eye. For example, it is set to about 200 Hz, and one scanning cycle is 5 ms. In the comparative technique, the light amount (luminance) of each LED is controlled by analog dimming (DC dimming), but it is difficult to dynamically change the output current I _OUT of the switching converter 12 within a scanning cycle of 5 ms. Therefore, the output current I _OUT is constant during one scan cycle, and therefore the illuminance of the irradiated portion included in one individual light distribution pattern PTN _i is uniform. When it is desired to form a bright part and a dark part in the final synthetic light distribution, it is necessary to control the brightness of each of the individual light distribution patterns PTN ₁ to PTN _N and superimpose them.

The present inventors have studied that in the vehicle lamp 100R of FIG. 1, the light intensity of each of the LEDs 4_1 to 4_N is changed within one scanning cycle by PWM-controlling the bypass switches SW1 to SWN.

Focus on one LED driver 10_1. Consider a situation in which the bypass switch SW1 is fixed to off and the bypass switch SW2 is switched. When the bypass switch SW2 is switched, the current I _LED2 flowing through the LED4_2 rings at the turn-off timing of the switch, that is, at the timing when the LED4_2 is turned on. This phenomenon is explained by charging / discharging the electric charge of the output capacitor C1 of the switching converter 12. FIG. 2 is a diagram (measurement result) showing a ringing waveform of the driving current of the LED.

The initial state is the state in which the bypass switch SW1 is off and the bypass switch SW2 is on. At this time, the output voltage V _OUT of the switching converter 12 becomes _VF . _VF is a forward voltage of one LED.

When the bypass switch SW2 is turned off, the switching converter 12 needs to raise its output voltage V _OUT to 2 × VF, and has to charge the output capacitor C1 with the charge of _C × _VF . Therefore, immediately after the turn-off of the bypass switch SW2, a part of the output current I _OUT is consumed as the charging current of the capacitor C1, so that the output current I _OUT is insufficient. In the switching converter 12, feedback is applied so that the insufficient current approaches the target value, but the output current I _OUT rings due to the resonance of the inductor of the switching converter 12.

When the bypass switch SW2 is switched in this way, the current I _LED2 of the LED4_2 in parallel with the bypass switch SW2 rings. Not only that, the current I _LED1 of the LED4_1 that is always lit will also be ringing.

When the duration of ringing (hereinafter referred to as ringing time) was measured by an experiment, it was about 30 to 50 μs.

The PWM frequency of a general non-scanning lamp is about 300 Hz, and the PWM cycle is 3.3 ms. In this case, the ringing time of 50 μs is only about 5% of the PWM cycle, and the influence of ringing on the gradation control is small.

However, in the scanning lamp of FIG. 1, when the scanning frequency is 100 to 200 Hz, the PWM frequency needs to be several times or more, that is, several kHz. It can be said that this is a very high frequency as compared with the PWM frequency of about 300 Hz in a general non-scan type lamp.

For example, in a scanning lamp, when the PWM frequency is 20 kHz, the PWM cycle is 50 μs, which is about the same as the ringing time of 50 μs. Therefore, in the configuration of FIG. 1, it is practically difficult to perform PWM dimming at several tens of kHz by using the bypass switches SW1 and SW2.

Hereinafter, the vehicle lamp 100 according to the embodiment will be described.

FIG. 3 is a diagram showing a vehicle lamp 100A according to the first embodiment. The vehicle lamp 100A of FIG. 3 has a scan-type ADB function and forms various light distribution patterns in front of the vehicle. The vehicle lamp 100A mainly includes a scanning light source 200A, a lighting circuit 300A, and a light distribution controller 400.

The light distribution controller 400 receives and distributes information (sensor information) S1 and information (vehicle information) S2 such as vehicle speed and steering angle from sensors such as cameras and LiDAR (Light Detection and Ringing, Laser Imaging Detection and Ringing). Determine the light pattern. The light distribution controller 400 may be housed in the lamp body or may be provided on the vehicle side. The light distribution controller 400 transmits information (light distribution pattern information) S3 indicating a light distribution pattern to the vehicle lamp 100. The light distribution controller 400 is also referred to as an ADB ECU (Electronic Control Unit).

The scanning light source 200A includes a light source unit 210A, a scanning optical system 220, and a projection optical system 230. The light source unit 210A includes one semiconductor light source 212 and a heat sink (not shown). An LED (light emitting diode), a laser diode, or the like can be used as the semiconductor light source 212. The scanning optical system 220 scans the emitted light (beam) BM of the semiconductor light source 212 in front of the vehicle.

In the present embodiment, the scanning optical system 220 includes a motor 222 and one or a plurality of M (two in this example) blade mirrors 224_1224_2. The M blade mirrors (M ≧ 2) are mounted at 360 / M ° offset positions, and in this example, the two blade mirrors are mounted at 180 ° offset positions.

The optical axis of the semiconductor light source 212 is directed so that the emitted beam BM irradiates one of the M blade mirrors.

At a certain time, the incident light BM on the blade mirror 224 is reflected at a reflection angle corresponding to the position of the blade mirror 224 (rotation angle of the rotor), and an instantaneous irradiation spot SPT is formed on the virtual vertical screen 900 in front of the vehicle. The instantaneous irradiation spot SPT has a width Δv in the horizontal direction (H direction) and a width Δh in the vertical direction (V direction). The rotation of the blade mirror 224 changes the reflection angle, that is, the emission direction of the reflected beam BMr, and the horizontal (H direction) position (scanning position) of the instantaneous irradiation spot SPT moves. By repeating this operation at high speed, for example, at 50 Hz or higher, a light distribution pattern PTN is formed in front of the vehicle.

In the present embodiment, the light distribution pattern PTN formed by one beam BM extends over the entire horizontal range of the vehicle lamp 100A to _−θMAX to + _θMAX . That is, the scanning light source 200A scans the reflected beam BMr over the entire horizontal range. For example, θ _MAX is about 20 to 25 °. The entire range is the entire range that can be irradiated by scanning, and does not include the range irradiated by a light source other than scanning.

The lighting circuit 300A determines the amount of light of the semiconductor light source 212 at each scanning position, that is, the intensity of the beam BM, in synchronization with the scanning of the scanning light source 200A so that the light distribution pattern indicated by the light distribution pattern information S3 can be obtained. Dimming with multiple gradations by pulse modulation. In the present embodiment, the average amount of drive current I _LEDs flowing through the semiconductor light source 212 is changed by PWM (pulse width modulation), and the amount of light of the semiconductor light source 212 is changed (PWM dimming). The PWM frequency is set sufficiently higher than the scanning frequency, and it is desirable that the PWM frequency is, for example, several kHz to several hundred kHz.

The lighting circuit 300A may change the amount of current I _OUT in a scanning cycle or a control cycle longer than that. That is, PWM dimming and DC dimming may be used together. The above is the configuration of the vehicle lamp 100A. Next, the operation will be described.

4 (a) and 4 (b) are diagrams illustrating the formation of glare-free light distribution by the vehicle lamp 100A. The glare-free light distribution 910 of FIG. 4A includes a light-shielding portion 912 and an irradiation portion 914,916. 4 (a) shows the light distribution on the virtual vertical screen, and FIG. 4 (b) shows the operation waveform of the vehicle lamp 100A corresponding to the light distribution of FIG. 4 (a). The vertical and horizontal axes of the waveform charts and time charts referred to in the present specification are appropriately enlarged or reduced for easy understanding, and each waveform shown is also simplified for easy understanding. It is made, or exaggerated or emphasized.

For example, the lighting circuit 300A sets the duty cycle of the drive current I _LED of the semiconductor light source 212 to a non-zero value (100% constant value in this example) in the section corresponding to the

irradiation portions

914 and 916, and corresponds to the light shielding portion 912. In this section, the duty cycle of the drive current I _LED is set to 0%.

5 (a) and 5 (b) are diagrams illustrating the formation of a partially dimmed light distribution by the vehicle lamp 100A. 5 (a) shows the horizontal illuminance distribution of the light distribution on the virtual vertical screen, and FIG. 5 (b) shows the operation waveform of the vehicle lamp 100A corresponding to the light distribution of FIG. 5 (a). The partial dimming distribution 920 shown in FIG. 5A includes two dimming portions 922,924 and three non-dimming portions 926,927,928.

For example, in the lighting circuit 300A, the duty cycle of the drive current I _LED of the semiconductor light source 212 is fixed to 100% in the section corresponding to the non-dimming portion (irradiation portion) 926,927,928, and the duty cycle is fixed to the dimming portion 922,924. In the corresponding section, the duty cycle of the drive current I _LED is 50% and 25%, respectively. According to the vehicle lamp 100A, partial dimming can be realized by PWM-controlling the drive current I _LED flowing through a single semiconductor light source.

6 (a) and 6 (b) are diagrams illustrating an electronic swivel by a vehicle lamp 100A. FIG. 6A shows the brightest light distribution in the center, and FIG. 6B shows the brightest light distribution on the right side. According to the vehicle lamp 100A, the electronic swivel function can be realized by PWM-controlling the drive current I _LED flowing through a single semiconductor light source.

The above is the operation of the vehicle lamp 100A. The advantages of the vehicle lamp 100A are further clarified by comparison with the comparative technique. Therefore, the comparative technique will be described. FIG. 7 is a diagram showing a vehicle lamp 100R according to the comparative technique.

In the vehicle lamp 100R according to the comparative technique, the light source unit 210R includes a plurality of semiconductor light sources 212_1 to 212_N. Each of the emission beams BM ₁ to BM _N of the semiconductor light sources 212_1 to 212_N is scanned in different horizontal ranges on the virtual vertical screen 900, and a plurality of individual light distribution patterns are scanned by scanning the emission beams BM ₁ to BM _N. PTN ₁ to PTN _N are formed. The light distribution formed by the vehicle lamp 100R is a superposition of a plurality of individual light distribution patterns PTN ₁ to PTN _N.

The lighting circuit 300R supplies drive currents I _LED1 to I _LEDN to each of the plurality of semiconductor light sources 212_1 to 212_N. The lighting circuit 300R can turn on and off the drive currents I _LED1 to I _LEDN , respectively, within one cycle. Further, the lighting circuit 300R can control the amount of current during the on period of each of the drive currents I _LED1 to I _LEDN by DC dimming, but the amount of current can be switched only for each scan.

FIG. 8 is a diagram illustrating light distribution formation by the vehicle lamp 100R according to the comparative technique. Here, N = 6 channels. The irradiation widths of the plurality of individual light distribution patterns PTN ₁ to PTN ₆ are controlled. By superimposing them, a light distribution pattern with a bright left front is formed in this example.

Return to embodiment 1. According to the vehicle lamp 100A according to the first embodiment, by adopting pulse modulation, the light amount of the light source can be changed at high speed according to the scanning position within one scanning cycle. Therefore, as compared with the conventional analog dimming in which the amount of light is constant within one scanning cycle, the variation of the light distribution that can be formed by one light source increases. As a result, the number of light sources and lighting circuits can be reduced as compared with the conventional case, or control can be simplified.

The present disclosure is grasped as a block diagram and a circuit diagram of FIG. 1, and extends to various devices and circuits derived from the waveform diagrams of FIGS. 3 to 4 or the above description, and is limited to a specific configuration. It's not a thing. Hereinafter, a more specific configuration example will be described not to narrow the scope of the present disclosure but to facilitate and clarify the essence of the disclosure and the circuit operation.

A specific configuration example of the lighting circuit 300A will be described. FIG. 9 is a block diagram showing a configuration example of the lighting circuit 300A.

The light distribution controller 400 receives sensor information S1 and vehicle information S2. The light distribution controller 400 detects the situation in front of the vehicle, specifically, the presence / absence of an oncoming vehicle, a preceding vehicle, the presence / absence of a pedestrian, and the like based on the sensor information S1. Further, the light distribution controller 400 detects the current vehicle speed, steering angle, and the like based on the vehicle information S2. Based on these information, the light distribution controller 400 determines a light distribution pattern to be irradiated to the front of the vehicle, and transmits information (light distribution pattern information) S3 instructing the light distribution pattern to the lighting circuit 300A.

The lighting circuit 300A changes the light amount (luminance) of the semiconductor light source 212 in multiple gradations by PWM dimming while synchronizing with the rotation of the blade mirror 224 based on the light distribution pattern information S3. For example, the lighting circuit 300A mainly includes a position detector 302, a PWM signal generation unit 310, and a constant current driver (hereinafter referred to as LED driver) 320.

The position detector 302 is provided to detect the position of the blade mirror 224, in other words, the scanning position of the current beam. The position detector 302 generates a position detection signal S4 indicating the timing at which the predetermined reference point of the blade mirror 224 passes the predetermined position. For example, the reference portion may be the end portion (separation) of the two blade mirrors 224, or may be the center of each blade mirror, and may be any location.

A Hall element may be attached to the motor 222 that rotates the blade mirror 224. In this case, the Hall signal from the Hall element has a periodic waveform corresponding to the position of the rotor, that is, the position of the blade mirror. The position detector 302 may detect the timing at which the polarity of the Hall signal is inverted, and specifically, may be configured by a Hall comparator that compares a pair of Hall signals.

The position detection method of the blade mirror 224 by the position detector 302 is not limited to the one using a Hall element. For example, the position detector 302 may generate the position detection signal S4 by using an optical or other rotary encoder that detects the position of the rotor of the motor 222. Alternatively, the position detector 302 may include a photosensor provided on the back side of the blade mirror 224 and a light source for position detection that irradiates light from the surface side of the blade mirror 224 toward the photosensor. Then, the blade mirror 224 may be provided with a slit or a pinhole. This makes it possible to detect when the slit or pinhole passes over the photo sensor. The slit may be a gap between the two blade mirrors 224. Further, the light source for position detection may be an infrared light source or a semiconductor light source 212. As described above, there may be various variations in the configuration of the position detector 302.

The PWM signal generation unit 310 generates a pulse dimming signal PWM_DIM in synchronization with the movement of the blade mirror 224. The duty cycle of one scan cycle of the pulse dimming signal PWM_DIM is defined based on the light distribution pattern. For example, when the rotation speed of the motor 222 is 6000 rpm (100 Hz) and the number of blade mirrors is two, the scanning frequency is 100 Hz × 2 = 200 Hz, and the scanning cycle is 5 ms. The PWM signal generation unit 310 may be implemented by combining the microcontroller 304 and the software program, or may be implemented only by hardware. The microcontroller 304 and the LED driver 320 may be mounted on one substrate or may be arranged in one housing.

The frequency of the pulse dimming signal PWM_DIM is set higher than 200 Hz, and can be, for example, several kHz to several tens of kHz. The duty cycle of the pulse dimming signal PWM_DIM determines the amount of light of the semiconductor light source 212, and the duty cycle may be set for each PWM cycle or may be set for each of a plurality of PWM cycles. good.

The LED driver 320 supplies a drive current I _LED to the semiconductor light source 212. The current amount of the drive current I _LED is stabilized to a predetermined target value, and the LED driver 320 switches the drive current I _LED according to the pulse dimming signal PWM_DIM.

FIG. 10 is a circuit diagram showing a configuration example (320A) of the LED driver 320. The LED driver 320A includes a buck converter 322, a series switch 323, and a driver circuit 324. The series switch 323 and the semiconductor light source 212 are connected in series. In this example, the series switch 323 is inserted on the anode side of the semiconductor light source 212, but may be inserted between the cathode and the ground.

The buck converter 322 is a constant current output switching converter and includes an output circuit 326 and a converter controller 328. The output circuit 326 includes a switching transistor MH, a synchronous rectifying transistor ML, an inductor L1, and an output capacitor C1. The converter controller 328 switches and controls the switching transistor MH and the synchronous rectifying transistor ML of the output circuit 326 so that the output current I _OUT of the buck converter 322 approaches a predetermined target amount while the series switch 323 is on.

The control method of the converter controller 328 is not particularly limited, and may be an analog controller using an error amplifier, a digital controller including a PID (proportional / integral / differential) compensator, or a hysteresis control controller.

The driver circuit 324 drives the series switch 323 in response to the pulse dimming signal PWM_DIM. The driver circuit 324 may be integrated in the same IC as the converter controller 328.

The converter controller 328 stops the switching of the switching transistor MH and the synchronous rectifying transistor ML when the pulse dimming signal PWM_DIM is at the off level indicating the off of the series switch 323.

The above is the configuration of the LED driver 320A. In this LED driver 320A, since the output current I _OUT of the buck converter 322 is cut off and the continuity is switched at high speed by the series switch 323, it is not necessary to change the output voltage V _OUT of the buck converter 322 in a stepwise manner. As a result, ringing of the output current I _OUT due to charging / discharging of the output capacitor C1 can be suppressed, and dimming by high-speed pulse modulation of several kHz to several tens of kHz becomes possible.

FIG. 11A is a diagram showing current control by a series switch, and FIG. 11B is a diagram showing current control by a bypass switch. These waveforms show one cycle of PWM dimming, the PWM frequency is 5 kHz (200 μs cycle), and the duty cycle is 50%.

As shown in FIG. 11B, in the PWM dimming by the bypass switch, ringing occurs in the output current of the buck converter 322, that is, the LED current, whereas in the PWM dimming by the series switch, FIG. 11 (a). ), The ringing of the LED current can be suppressed. As a result, gradation control by PWM dimming becomes possible even in a region where the duty cycle is small.

Further, during the period when the series switch 323 is off, the converter controller 328 stops switching between the switching transistor MH and the synchronous rectifying transistor ML. As a result, the voltage V _OUT of the output capacitor C1 is kept constant during the period when the series switch 323 is off, so that the fluctuation amount of the output voltage V _OUT immediately after the series switch 323 is turned on can be brought close to zero. .. As a result, ringing of the output current I _OUT can be further suppressed.

FIG. 12 is a circuit diagram showing a configuration example of the LED driver 320A. The LED driver 320A includes a control IC (Integrated Circuit) 340. In addition to the converter controller 328, the control IC 340 integrates a switching transistor MH, a synchronous rectifier transistor ML, and a driver circuit 324.

The output circuit 326 includes a current detection resistor Rcs. The voltage across the current detection resistor Rcs is fed back to the ISP / ISN pin of the control IC. The transconductance amplifier 330 generates a current corresponding to an error of the current detection signal Vcs, which is the potential difference between the two terminals ISP and ISN, and the reference voltage Vref. The output of the transconductance amplifier 330 is connected to the Vc pin via the sample hold circuit 332. A resistor Rc and a capacitor Cc are connected to the Vc pin. The resistance Rc and the capacitor Cc also serve as a phase compensation circuit. The resistance Rc may be omitted. The capacitor Cc is charged and discharged according to the output current of the transconductance amplifier 330, so that an error voltage Vc is generated in the Vc pin. Due to the feedback, this error voltage Vc increases or decreases so that the current detection signal Vcs approaches the reference voltage Vref. The transconductance amplifier 330 and the phase compensation circuits Rc and Cc are grasped as an error amplifier.

The on-time control unit 334 is a pulse width modulator, and generates a control pulse Spwm having a duty cycle corresponding to an error voltage Vc. The frequency of this control pulse Spwm is set even higher than the pulse dimming signal PWM_DIM. The configuration of the on-time control unit 334 is not particularly limited, but may include an oscillator that generates a periodic voltage such as a triangular wave or a sawtooth wave, and generate a control pulse Spwm by comparing the periodic voltage and the error voltage Vc. ..

The gate driver 336 drives the switching transistor MH and the synchronous rectifying transistor ML according to the control pulse Spwm.

The PWM signal generation unit 310 is composed of a microcontroller. A pulse dimming signal PWM_DIM generated by the PWM signal generation unit 310 is input to the PWM pin of the control IC 340. The driver circuit 324 receives the pulse dimming signal PWM_DIM and drives the series switch 323. In this embodiment, the series switch 323 is a polyclonal transistor, and the driver circuit 324 outputs a signal obtained by inverting the pulse dimming signal PWM_DIM from the PWMG pin.

The pulse dimming signal PWM_DIM is input to the sample hold circuit 332. The sample hold circuit 332 connects the output of the transconductance amplifier 330 to the Vc pin and the input of the on-time control unit 334 during the on-level (high) period in which the pulse dimming signal PWM_DIM instructs the series switch 323 to turn on. Further, the sample hold circuit 332 maintains the connection between the Vc pin and the input of the on-time control unit 334 during the off-level (low) period in which the pulse dimming signal PWM_DIM instructs the series switch 323 to be turned off, while maintaining the connection of the transconductance amplifier 330. The output is cut off from the Vc pin and the on-time control unit 334. As a result, the error voltage Vc of the Vc pin is held during the period when the pulse dimming signal PWM_DIM is off, and when the next pulse dimming signal PWM_DIM is turned on, the error voltage Vc is immediately returned to the appropriate voltage level. Can be made to.

The pulse dimming signal PWM_DIM is input to the gate driver 336. The gate driver 336 selectively switches the switching transistor MH and the synchronous rectifying transistor ML according to the control pulse Spwm during the period when the pulse dimming signal PWM_DIM is on level (high). Further, the gate driver 336 stops switching between the switching transistor MH and the synchronous rectifying transistor ML during the period when the pulse dimming signal PWM_DIM is off level (low). Specifically, the gate driver 336 fixes both the switching transistor MH and the synchronous rectifying transistor ML to off during the period when the pulse dimming signal PWM_DIM is off level.

FIG. 13 is a circuit diagram showing another configuration example (320B) of the LED driver 320. The LED driver 320B includes a buck converter 322, a bypass switch SW2, and a driver circuit 324. The buck converter 322 may include an output circuit 326 and a converter controller 328, as in FIG. The buck converter 322 produces a regulated output current I _OUT to a predetermined target amount.

The bypass switch SW2 is connected in parallel with the semiconductor light source 212. The driver circuit 324 drives the bypass switch SW2 in response to the pulse dimming signal PWM_DIM. During the off period of the bypass switch SW2, the output current I _OUT is supplied to the semiconductor light source 212 as the drive current I _LED , and during the on period of the bypass switch SW2, the output current I _OUT flows to the bypass switch SW2, so that the drive current I _LED Is zero.

FIG. 14 is a circuit diagram showing still another configuration example (320C) of the LED driver 320. The LED driver 320C includes a constant voltage converter 327 and a constant current source 329. The constant voltage converter 327 produces an output voltage V _OUT stabilized at a predetermined voltage level. The constant current source 329 is connected in series with the semiconductor light source 212. The constant current source 329 can be switched on and off, and during the on period, a predetermined amount of stabilized drive current I _LED is generated (sink). The on / off of the constant current source 329 is controlled according to the pulse dimming signal PWM_DIM.

The configuration of the LED driver 320 is not limited to the one illustrated here.

(Embodiment 2)
FIG. 15 is a diagram showing a vehicle lamp 100B according to the second embodiment. Differences from the first embodiment will be described.

The light source unit 210B of the scanning light source 200B includes a plurality of N (N ≧ 2) semiconductor light sources 212_1 to 212_N. The optical axes of the semiconductor light sources 212_1 to 212_N are directed so that the respective emitted beams BM ₁ to BM _N irradiate one of the M blade mirrors. Here, only the light beam of the emitted beam BM ₂ of the semiconductor light source 212_2 is shown as a representative.

At a certain time, the incident light BM ₂ on the blade mirror 224 is reflected at a reflection angle corresponding to the position of the blade mirror 224 (rotation angle of the rotor), and an instantaneous irradiation spot SPT ₂ is formed on the virtual vertical screen 900 in front of the vehicle. do. The instantaneous irradiation spot SPT ₂ has a predetermined width in each of the horizontal direction (H direction) and the vertical direction (V direction). As the blade mirror 224 rotates, the reflection angle changes, the emission direction of the reflected beam BMr ₂ changes as shown by the broken line, and the horizontal (H direction) position (scanning position) of the instantaneous irradiation spot SPT ₂ moves. do. By repeating this operation at high speed, for example, at 50 Hz or higher, an individual light distribution pattern PTN ₂ is formed in front of the vehicle.

The same applies to the other beams BM ₁ , BM ₃ to BM _N , and the individual light distribution pattern PTN _i is formed by scanning the i-th reflected beam BM r _i .

For example, the individual light distribution patterns PTN ₁ to PTN _N formed by the beams BM ₁ to BM _N are formed at different heights on the virtual vertical screen 900. By synthesizing a plurality of individual light distribution patterns PTN ₁ to PTN _N , the light distribution pattern PTN_ALL of the entire vehicle lamp 100 is formed. The individual light distribution patterns PTNs adjacent to each other in the vertical direction may slightly overlap each other in the vertical direction.

In the second embodiment, at least one of the plurality of individual light distribution patterns PTN ₁ to PTN _N extends over the entire horizontal range of the vehicle lamp 100 to _−θMAX to + _θMAX . That is, the scanning light source 200B scans at least one of the plurality of beams BMr ₁ to BMr _N over the entire horizontal range. In the example of FIG. 15, all the individual light distribution patterns PTN ₁ to PTN _N extend over the entire horizontal range −θ _MAX to + θ _MAX .

The lighting circuit 300B adjusts the light intensity of each of the semiconductor light sources 212_1 to 212_N at each scanning position, that is, the intensity of the beams BM ₁ to BM _N in multiple gradations in synchronization with the scanning of the scanning light source 200B. .. The lighting circuit 300B may change the amount of current I _OUT in a scanning cycle or a control cycle longer than that. That is, PWM dimming and DC dimming may be used together.

FIG. 16 is a block diagram showing a configuration example of the lighting circuit 300B of FIG. The lighting circuit 300B includes a plurality of LED drivers 320_1 to 320_N corresponding to the plurality of semiconductor light sources 212_1 to 212_N. The PWM signal generation unit 310 generates pulse dimming signals PWM_DIM_1 to PWM_DIM_N for a plurality of LED drivers 320_1 to 320_N so that the desired light distribution can be obtained. The i-th (1 ≦ i ≦ N) LED driver 320 supplies a PWM-modulated drive current I _LEDi to the corresponding semiconductor light source 212_i. The configuration of the LED driver 320 is the same as that of the first embodiment.

According to this vehicle lamp 100B, the resolution in the height direction can be improved as compared with the first embodiment.

A modified example of the second embodiment will be described. In the above explanation, all of the plurality of light distribution patterns PTN ₁ to PTN _N are spread over the entire range, but not limited to this, and some of them are spread over a part of the range, not the entire range. You may.

In the second embodiment, the entire light distribution is vertically divided into a plurality of regions, and a plurality of individual light distribution patterns PTN ₁ to PTN _N are associated with the plurality of regions, but this is not the case. Some of the plurality of individual light distribution patterns PTN ₁ to PTN _N may completely overlap.

(Embodiment 3)
FIG. 17 is a diagram showing a vehicle lamp 100C according to the third embodiment. Similar to the second embodiment, the light source unit 210C includes a plurality of semiconductor light sources 212_1 to 212_N. In the first embodiment or the second embodiment, the emitted beams BM ₁ to BM _N of the semiconductor light sources 212_1 to 212_N are irradiated over the entire range of the horizontal scan, but in the third embodiment, the emitted beams BM ₁ to BM _N are emitted. , Different horizontal ranges are scanned on the virtual vertical screen 900, and the scanning of the emitted beams BM ₁ to BM _N forms a plurality of individual light distribution patterns PTN ₁ to PTN _N. The light distribution formed by the vehicle lamp 100R is a superposition of a plurality of individual light distribution patterns PTN ₁ to PTN _N.

The lighting circuit 300C can be configured in the same manner as the lighting circuit 300B of the second embodiment.

(Short abnormality detection of series switch)
When PWM dimming is performed by the series switch, if a short circuit error occurs in the series switch, the drive current I _LED to the semiconductor light source 212 cannot be cut off, the semiconductor light source 212 lights up, and the correct light distribution cannot be formed. Specifically, the dimming cannot be sufficiently performed, which may cause glare on the oncoming vehicle and the preceding vehicle.

Note that the short-circuit abnormality cannot cut off the current supply to the semiconductor light source 212 even if the pulse dimming signal PWM_DIM is turned off, such as an abnormality in which the series switch cannot be turned off or an abnormality in which both ends of the series switch are short-circuited. It means an abnormality.

The following describes vehicle lamps that can detect short-circuit abnormalities in series switches.

FIG. 18 is a block diagram of a vehicle lamp 100F having a short abnormality detection function. The vehicle lamp 100F includes a semiconductor light source 212, an LED driver 320F, and a PWM signal generation unit 310. The PWM signal generation unit 310 generates a pulse dimming signal PWM_DIM pulse-modulated so as to form a desired light distribution pattern.

The LED driver 320F includes a buck converter 322, a series switch 323, and a driver circuit 324, similarly to the LED driver 320A of FIG. These functions and operations are as described above. That is, the buck converter 322 outputs a constant current during the on period (i) of the series switch 323 (the period during which the pulse dimming signal PWM_DIM is on level). Further, the buck converter 322 stops the switching operation during the off period of the (ii) series switch 323 (the period during which the pulse dimming signal PWM_DIM is at the off level), and has substantially the same output voltage V _OUT , that is, the semiconductor as the immediately preceding on period. It is configured to maintain the forward voltage of the light source 212.

The LED driver 320F further includes an abnormality detection circuit 370. When the output voltage V _OUT of the buck converter 322 deviates from the normal range during the off period of the series switch 323, the abnormality detection circuit 370 determines that the series switch 323 is abnormal and asserts the abnormality detection signal (fail signal) FAIL. The fail signal FAIL is transmitted to the PWM signal generation unit 310 or an upper block such as another microcontroller, processor, or ECU. The PWM signal generation unit 310 that has received the fail signal FAIL may stop the generation of the pulse dimming signal PWM_DIM and turn off the semiconductor light source 212.

19 (a) and 19 (b) are diagrams illustrating the operation of the vehicle lamp 100F of FIG. Here, an operation for one scan is taken as an example when forming a light distribution including two light-shielding portions and one dimming portion.

The operation when the series switch 323 is normal will be described with reference to FIG. 19 (a). The pulse dimming signal PWM_DIM is an off-level (low) in the light-shielding portion, a pulse signal having a duty cycle according to the dimming rate in the dimming portion, and an on-level (high) in the other portion. Take.

When the pulse dimming signal PWM_DIM is high (on level), the series switch 323 conducts, so that the constant current I _OUT generated by the buck converter 322 is supplied to the semiconductor light source 212, and the drive current I flows through the semiconductor light source 212. The _LED is stabilized to a constant current I _OUT . At this time, the output voltage V _OUT of the buck converter ₃₂₂ becomes equal to the forward voltage VF of the semiconductor light source 212.

When the pulse dimming signal PWM_DIM is low (off level), the series switch 323 is cut off, so that the drive current I _LED flowing through the semiconductor light source 212 becomes 0A. Further, since the switching operation of the buck converter 322 is stopped and charging / discharging to the output capacitor C1 does not occur, the output voltage V _OUT is kept at a substantially constant level.

Thus, when the series switch 323 is normal, the output voltage V _OUT of the buck converter 322 is in a certain voltage range near the forward voltage _VF regardless of whether the series switch 323 is on or off (this). Is included in the normal range).

The operation when a short-circuit abnormality occurs in the series switch 323 will be described with reference to FIG. 19 (b). The pulse dimming signal PWM_DIM is the same as that in FIG. 19A.

Even if a short-circuit error occurs, when the pulse dimming signal PWM_DIM is high (on level), it operates in the same way as normal, but when the pulse dimming signal PWM_DIM is low (off level), it is for vehicles. The lamp 100F behaves differently from the normal state.

That is, even if the pulse dimming signal PWM_DIM is low (off level), the series switch 323 cannot be cut off, so that the drive current I _LED continues to flow in the semiconductor light source 212. However, since the switching of the buck converter 322 is stopped while the pulse dimming signal PWM_DIM is low, the drive current I _LED is covered by the discharge of the output capacitor C1 of the buck converter 322. Therefore, as the discharge progresses, the drive current I _LED decreases with time. Since the low section of the pulse dimming signal PWM_DIM is long in the light-shielded portion, when the output capacitor C1 is discharged and drops to the lighting start voltage V _MIN shown in FIG. 21, the drive current I _LED drops to 0 A. At this point, the discharge of the output capacitor C1 is stopped, so that the output voltage V _OUT is near the lighting start voltage V _MIN . On the other hand, in the dimmed portion, since the low section of the pulse dimming signal PWM_DIM is short, the drive current I _LED may not decrease to 0A.

In this way, when a short-circuit abnormality of the series switch 323 occurs, the drive current I _LED hardly decreases in the dimmed portion, which may cause glare to the oncoming vehicle or make it difficult for the driver to recognize the target. ..

Focusing on the low section of the pulse dimming signal PWM_DIM at the time of a short-circuit abnormality, the output capacitor C1 is discharged via the semiconductor light source 212, so that the output voltage V _OUT drops. As a result, it can be seen that it deviates from the normal range described in FIG. 19 (a).

According to this embodiment, the output voltage V _OUT can be detected by utilizing the difference in the behavior of the output voltage V _OUT at the time of short circuit abnormality and the normal state.

Hereinafter, a specific configuration of the abnormality detection circuit 370 and a specific signal processing will be described based on some examples.

FIG. 20 is a circuit diagram of the abnormality detection circuit 370 according to the embodiment. The abnormality detection circuit 370 includes a comparison circuit 372 and a signal processing unit 374. The comparison circuit 372 includes resistors R31 and R32 and a voltage comparator COMP1. The output voltage V _OUT of the buck converter 322 is divided by a voltage divider circuit including resistors R31 and R32. The voltage comparator COMP1 compares the output voltage V _OUT'after voltage division with a predetermined threshold voltage _VTH , and generates a detection signal S _DET indicating the comparison result. The detection signal S _DET is a binary signal indicating whether or not the output voltage V _OUT of the buck converter 322 is included in the normal range. In this configuration, _VSHORT = _VTH × (R31 + R32) / R32 is the threshold value (lower limit) in the normal range.

For example, in the normal state, V _OUT > V _SHORT , and the detection signal S _DET at this time keeps high. When a short-circuit abnormality occurs, every time the pulse dimming signal PWM_DIM becomes an off level, V _OUT <V _SHORT becomes V OUT <V SHORT, and the detection signal S _DET becomes low. By binarizing with the comparison circuit 372, it becomes easy to determine a short circuit abnormality by digital signal processing using a microcontroller or a logic circuit.

The signal processing unit 374 determines the presence or absence of a short-circuit abnormality based on the detection signal S _DET , and when the abnormality is detected, asserts the fail signal FAIL. Specifically, in the signal processing unit 374, the detection signal S _DET reaches a predetermined level (low), that is, the output voltage V _OUT of the buck converter 322 becomes a predetermined threshold value V _SHORT during the off period of the series switch 323. It is a condition of abnormality judgment that it is less than.

The signal processing unit 374 can be implemented by combining a microcontroller and software. In this case, the PWM signal generation unit 310 and the signal processing unit 374 may be mounted on the same microcontroller. The signal processing unit 374 may be configured by a hardware logic circuit.

FIG. 21 is a diagram showing the IV characteristics of the semiconductor light source 212. The lower limit threshold V _SHORT in the normal range may be set higher than the lighting start voltage V _MIN of the semiconductor light source 212 and lower than the forward voltage _VF when the semiconductor light source 212 is lit.

Immediately after the start of operation of the buck converter 322, the output voltage V _OUT is 0 V, so that an abnormality cannot be determined based on the output voltage V _OUT . Therefore, the abnormality detection by the abnormality detection circuit 370 is invalidated after the operation of the buck converter 322 is started until the output voltage V _OUT exceeds a predetermined voltage.

Subsequently, a specific example of the determination process by the abnormality detection circuit 370 will be described.

(Judgment process 1)
FIG. 22 is a diagram illustrating the determination process 1 of the abnormality detection circuit 370. FIG. 22 shows the waveform at the time of short circuit abnormality. As shown in FIG. 3, the vehicle lamp 100 includes a scanning optical system 220. The pulse dimming signal PWM_DIM is generated so that the series switch 323 is turned off for a predetermined period (referred to as blank period _TBLANK ) at the break between scans. For example, when the scanning optical system 220 includes a plurality of blade mirrors 224, the gap between the blade mirrors can be set as a blank period _TBLANK .

For example, when the scanning frequency is 200 Hz, the scanning period _TSCAN is 5 ms. When the PWM frequency is 20 kHz, the PWM cycle is 50 μs. The blank period _TBLANK may be set longer than the PWM cycle of 50 μs, for example 70 μs.

The abnormality detection circuit 370 detects an abnormality of the series switch 323 based on the output voltage V _OUT of the step-down converter 322 in the blank period _TBLANK . The abnormality detection circuit 370 sets a tentative determination state when the output voltage V _OUT falls below the threshold value V _SHORT in the blank period _TBLANK . Then, when the provisional determination state is established over a predetermined number of scans, the final determination may be performed.

Specifically, the signal processing unit 374 acquires the position of the blank period _TBLANK based on the position detection signal S4, and the detection signal _SDET transitions to a predetermined level (low) during the blank period _TBLANK . Is a condition for determining a short circuit abnormality. When the provisional determination state in which the detection signal S _DET becomes low in the blank period _TBLANK is established several times M a predetermined number of times, the fail signal FAIL is asserted. For example, the signal processing unit 374 includes a counter, and counts up the counter each time the detection signal S _DET of the blank period _TBLANK becomes low. Then, when the count value reaches a predetermined value M, the fail signal FAIL is asserted. If the low detection signal S _DET cannot be detected before the count value reaches the predetermined value M, the counter may be reset. That is, in the determination process 1, the short-circuit abnormality is detected by focusing only on the hatched portion of the detection signal S _DET in FIG. 22.

The advantages of the determination process 1 will be described. If the blank period _TBLANK is not provided, the short circuit abnormality cannot be detected unless the pulse dimming signal PWM_DIM transitions to low. In the first determination process, by inserting the blank period _TBLANK , an opportunity for abnormality determination is always given once per scan. This makes it possible to reliably detect a short circuit abnormality in a short time.

The PWM dimming section and the low section of the detection signal S _DET are narrow pulses shorter than 50 μs. Therefore, in order to use the detection signal S _DET in the PWM dimming section, a high-speed signal processing unit 374 is required. Further, when the duty cycle of the pulse dimming signal PWM_DIM is large (when the low section is short), the output voltage V _OUT may not fall below the threshold value V _SHORT . In the blank period _TBLANK longer than the PWM cycle, the output voltage V _OUT surely falls below the threshold value V _SHORT , so that a low-level detection signal S _DET can be generated, and a short-circuit abnormality can be detected stably.

(Judgment process 2)
FIG. 23 is a diagram illustrating the determination process 2 of the abnormality detection circuit 370. FIG. 23 shows the waveform at the time of short circuit abnormality. In the determination process 2, the blank period _TBLANK is not essential.

In the determination process 2, the abnormality detection circuit 370 constantly monitors the detection signal S _DET , and a state in which the detection signal S _DET is not a DC signal (DC state), in other words, a pulse signal (pulse state) is a predetermined determination. If the time τ _{DET continues} , it is determined that the condition is abnormal and the fail signal FAIL is asserted.

For example, the signal processing unit 374 generates a provisional determination signal DC / PULSE indicating whether the detection signal S _DET is in the pulse state or the DC state. A state in which the detection signal S _DET is continuously high for a predetermined time or longer may be a DC state, and a state in which the detection signal S DET is continuously high may be a pulse state. When the temporary determination signal DC / PULSE is high indicating the pulse state for a predetermined determination time τ _DET , the signal processing unit 374 determines that the temporary determination signal DC / PULSE is an abnormal state and asserts the fail signal FAIL. The signal processing unit 374 may be implemented by using the timer resource of the microcontroller.

The determination process 1 requires timing synchronization with the blank period _TBLANK , whereas the determination process 2 has an advantage that timing synchronization is not required.

(Judgment process 3)
FIG. 24 is a diagram illustrating the determination process 3 of the abnormality detection circuit 370. FIG. 24 shows the waveform at the time of short circuit abnormality. In the determination process 3, the blank period _TBLANK is not essential.

In the determination process 3, the abnormality detection circuit 370 constantly monitors the detection signal S _DET , the number of times the detection signal S _DET transitions to low, in other words, the number of low pulses generated on the detection signal S _DET , in other words, the detection signal S. The number of negative edges of the _DET is counted, and when the count value exceeds a predetermined threshold value K, it is determined as an abnormal state.

From a certain point of view, some of the determination processes 1 to 3 can be regarded as a condition for abnormality determination that the output voltage V _OUT of the buck converter 322 is not constant and lasts for a predetermined time. From another point of view, it is understood that some of the determination processes 1 to 3 require that the switching state of the output voltage V _OUT of the buck converter 322 lasts for a predetermined determination time as a condition for abnormality determination. Will be done.

(Judgment process 4)
In the embodiment, the abnormality determination is performed after binarizing the output voltage V _OUT , but this is not the case. For example, a high-speed A / D converter may capture a waveform of an output voltage V _OUT , and the presence or absence of an abnormality may be determined based on the waveform.

(Fail mask processing)
As described above, the abnormality detection circuit 370 makes it a condition for abnormality determination that the output voltage V _OUT of the buck converter 322 deviates from a predetermined voltage range. Since the output voltage V _OUT of the buck converter 322 rises from 0V during the period when the buck converter 322 is switched and the series switch 323 is on, the output voltage V _OUT deviates from the predetermined voltage range immediately after the start of lighting. ing. That is, immediately after the start of lighting, a short circuit abnormality of the series switch cannot be detected. In order to solve this problem, it is advisable to mask the detection of short circuit abnormality (fail information) immediately after the start of lighting.

In the lighting circuit including the series switch 323, the output voltage V _OUT of the buck converter 322 does not increase during the period when the series switch 323 is off, that is, while the lamp is off. Even if the light is on, when PWM dimming (PWM dimming) is performed by the series switch 323, the rising speed of the output voltage V _OUT differs depending on the dimming rate. In other words, if a process that releases the mask after a certain period of time has elapsed from the start of lighting is incorporated, a situation may occur in which the output voltage V _OUT does not reach the specified voltage after a certain period of time, depending on the duty cycle, resulting in a fail state. May be erroneously detected.

FIG. 25 is a block diagram of the vehicle lamp 100H according to the embodiment. When the lighting command LAMP_ON is input to the lighting circuit 300H and the lighting command LAMP_ON is in a state of instructing lighting, the scanning light source 200A starts lighting. The rotation of the motor 222 may be started, for example, triggered by an ignition on, prior to the start of lighting.

The lighting circuit 300H includes a mask processing unit 376. The fail signal FAIL, which is the output of the abnormality detection circuit 370, is input to the mask processing unit 376. The mask processing unit 376 integrates the product of the duty cycle of the pulse dimming signal PWM_DIM and the lighting time, and generates a cumulative lighting time indicating the integrated result. Then, the cumulative lighting time is compared with a predetermined threshold value, and while the cumulative lighting time is lower than the threshold value, the fail signal FAIL which is the detection result of the abnormality detection circuit 370 is masked.

The mask processing unit 376 may be mounted on the same microcontroller 304H as the PWM signal generation unit 310 that generates the pulse dimming signal PWM_DIM. As described above, when the abnormality detection circuit 370 includes the comparison circuit 372 and the signal processing unit 374, the signal processing unit 374 and the PWM signal generation unit 310 can be mounted on the same microcontroller as the PWM signal generation unit 310. ..

26 (a) and 26 (b) are diagrams illustrating the operation of the mask processing unit 376. As shown in FIG. 26 (a), a light distribution pattern PTN including four regions having different brightness is taken as an example. The four regions RGN ₁ to RGN ₄ are any of a light-shielding region, a dimming region, and a non-dimming region, and each exists over an angle range of θ ₁ to θ ₄ .

26 (b) shows the duty cycle and pulse dimming signal PWM_DIM corresponding to the light distribution of FIG. 26 (a). When the scanning period is _TSCAN , the length of the time interval Ti corresponding to the _i -th region RGN _i is expressed by the equation (1).
T _i = T _SCAN × θ _i / 2θ _MAX … (1)
When the i-th region RGN _i is a light-shielding region, the duty cycle di of the pulse dimming signal _{PWM_DIM} is ₀ %, and when it is a dimming region, 0% <di <100%, which is the non-dimming region. In the case, di ₌ 100%. In this example, RGN ₁ and RGN ₄ are non-dimming regions and d ₁ = d ₄ = 100%, RGN ₂ is a light-shielding region and d ₂ = 0%, and RGN ₃ is a dimming region and d ₃ = 50. %.

If the light distribution pattern PTN is constant, the same duty cycle is repeated for each scanning cycle.

The cumulative lighting time τ of one scanning cycle, that is, the cumulative time when the pulse dimming signal PWM_DIM is on level (high) is
τ = T ₁ x d ₁ + T ₂ x d ₂ + T ₃ x d ₃ + T ₄ x d ₄
Will be. The cumulative lighting time τ of the two scan cycles is
τ = T ₁ x d ₁ + T ₂ x d ₂ + T ₃ x d ₃ + T ₄ x d ₄ + T ₅ x d ₅ + T ₆ x d ₆ + T ₇ x d ₇ + T ₈ x d ₈
Is. The cumulative lighting time τ _i from the lighting start time t ₀ to the i-th time interval _Ti is
τ _i = _Ti × di + τ _i _-1 … (2)
Will be. Since the duty cycle _di is proportional to the brightness, the duty cycle di is equivalent to the brightness ( _dimming rate) of each region, and a replacement thereof is also included in the present invention.

The signal processing unit 374 calculates the cumulative lighting time τ from the start of lighting, compares it with the threshold value τ _TH , and negates (unmasks) the mask signal MASK when τ> τ _TH . The threshold value τ _TH can be determined based on the specified voltage of the output voltage V _OUT . The larger the duty cycle, the faster the rate at which the cumulative time τ rises, and when the duty cycle is 0, the cumulative time τ becomes constant.

According to this embodiment, it is possible to accurately detect that the output voltage V _OUT exceeds the specified voltage by calculating the cumulative lighting time in consideration of the duty cycle of PWM dimming using the series switch.

Hereinafter, an example of calculating the cumulative lighting time in the mask processing unit 376 will be described.

(Example of first processing)
The addition process may be performed in units of region RGNs having the same duty cycle. The mask processing unit 376 calculates the length of the time interval _Ti for each region RGN _i , multiplies the length of the time interval _Ti by the duty cycle _di , and cumulatively adds them. When the cumulative time from the start of lighting to the _i -th section Ti is expressed as τ _i , it is calculated based on the equation (2), and when the cumulative lighting time τ _i exceeds the threshold value τ _TH , the mask signal MASK is negated. do.

FIG. 27 is a block diagram of the mask processing unit 376 according to the first processing example. When the mask processing unit 376 is implemented by software processing by a microcontroller, each block in the block diagram schematically shows a step of software processing.

The duty cycle di and the time length Ti _thereof are input to the mask processing unit ₃₇₆ every time the duty cycle changes, that is, every time the region changes. The duty cycle _di and its time length _Ti can be generated by the PWM signal generation unit 310. From the equation (1), the time length _{Ti of each region is proportional to the scanning period TSCAN} _. When the rotation speed of the motor fluctuates, the scanning period _TSCAN may be acquired and the time length _Ti may be calculated based on the equation (1). On the contrary, when the rotation speed of the motor is constant or the fluctuation can be ignored, T _SCAN and 2θ _MAX in the equation (1) are constants, so that θ _i can be used as _Ti . good.

The multiplier ₃₈₀ multiplies the duty cycle di by the time length _Ti . The memory 382 stores the cumulative time τ _i- _{1 up to the previous area RGN i-1} . The adder 384 adds the output di × Ti of the multiplier 380 and the value τ _i _-1 of the memory 382, and outputs _{τ i} _. The value of memory 382 is updated by τ _i .

The comparator 386 compares the cumulative time τ _i with the threshold τ _TH , asserts the mask signal MASK when τ _i <τ _TH (for example, high), and negates the mask signal MASK when τ _i <τ _TH . For example, low). The gate means 388 passes the fail signal FAIL when the mask signal MASK is negated, and shuts off the fail signal FAIL when the mask signal MASK is asserted. An abnormality of the series switch 323 is determined based on the fail signal FAIL_MASKED after masking.

The gate means 388 may be omitted, the mask signal MASK may be supplied to the abnormality detection circuit 370, and the operation of the abnormality detection circuit 370 may be stopped during the period in which the mask signal MASK is asserted.

(Second processing example)
In the first processing example, addition processing was performed for each area. In the second processing example, the addition processing is performed every one PWM cycle. It is assumed that the period Tpwm of the pulse dimming signal PWM_DIM is constant. In this case, the mask processing unit 376 integrates the duty cycle values for each PWM cycle Tpwm. Then, while the integrated value τ is lower than the predetermined threshold value τ _TH , the fail signal FAIL is masked.

FIG. 28 is a block diagram of the mask processing unit 376 according to the second processing example. The duty cycle _dj is input to the mask processing unit 376 for each PWM cycle (PWM pulse unit). d _j indicates the duty cycle in the jth PWM cycle from the start of lighting.

The memory 382 stores the cumulative time τj _-1 up to the previous PWM cycle. The adder 384 adds d _j and the value τ _j-1 of the memory 382, and outputs τ _j . The value of memory 382 is updated by _τj .

The comparator 386 compares the cumulative time _τj with the threshold _τTH , asserts the mask signal MASK when _τj < _τTH (for example, high), and negates the mask signal MASK when _τj < _τTH . For example, low). The processing after the generation of the mask signal MASK is omitted.

(Third processing example)
In the second processing example, it is assumed that the PWM cycle is constant, but it may be variable. FIG. 29 is a block diagram of the mask processing unit 376 according to the third processing example. The duty cycle _dj is input to the mask processing unit 376 for each PWM cycle (PWM pulse unit). d _j indicates the duty cycle in the jth PWM cycle from the start of lighting.

The duty cycle d _j and the cycle length Tpwm _j are input to the mask processing unit 376 for each PWM cycle. The configuration of the mask processing unit 376 is the same as that of the first processing example (FIG. 27).

Next, a modified example of the fail mask will be explained.

(Modification 1)
When the rising speed of the output voltage V _OUT during the period when the series switch 323 is on depends on the input voltage of the buck converter, in other words, the power supply voltage (ignition voltage) supplied to the lighting circuit 300H, the power supply voltage _VDD is used. The lighting period may be weighted by the corresponding coefficient K. In this case, the equation (2) in the first processing example may be modified as follows.
τ _i = _Ki x _Ti x di + τ _i _-1 ... (2')
When the power supply voltage _VDD fluctuates frequently, the power supply voltage _VDD is measured for each time interval _Ti or scan cycle, and for each time interval _Ti (or scan cycle) according to the power supply voltage _VDD . The coefficient _Ki may be updated.

If the power supply voltage can be regarded as constant immediately after the start of lighting, the power supply voltage may be measured only once, and the coefficient K corresponding to the power supply voltage _VDD0 may be used fixedly.
τ _i = K ₀ × T _i × di + τ _i _-1 … (2 ”)

Instead of weighting the cumulative time, the threshold value τ _TH may be changed according to the power supply voltage _VDD0 .

(Modification 2)
Further, when the scanning cycle T _SCAN fluctuates, the threshold value τ _TH may be changed according to the scanning cycle T _SCAN .

(Modification 3)
In the above description, the abnormality detection circuit 370 has determined to detect a short circuit of the series switch 323 based on the output voltage V _OUT of the buck converter 322, but this is not the case. For example, the anomaly detection circuit 370 may detect an open anomaly in place of or in addition to the short circuit of the series switch 323. Alternatively, an abnormality (ground fault, heaven fault, etc.) other than the series switch 323 may be monitored, and the present disclosure is applicable as long as the abnormality is detected based on the output voltage V _OUT of the buck converter 322.

(Suppression of vertical stripes due to PWM dimming)
When the scan-type light distribution formation is combined with pulse dimming, vertical stripes may occur. 30 (a) to 30 (c) are diagrams illustrating vertical stripes in a combination of scan-type light distribution formation and pulse dimming. FIG. 30A shows a light distribution pattern 800 in a certain traveling scene. In this driving scene, the sign 810 and the oncoming vehicle 812 are present in front of the vehicle, and the light distribution pattern 800 is arranged in the existence range of the dimming portion 802 arranged in the existence range of the sign 810 and the oncoming vehicle 812. Includes the shaded portion 804. Of the light distribution pattern 800, the illuminance of the portion 806 other than the dimming portion 802 and the light-shielding portion 804 is the maximum (100%), and the illuminance of the light-shielding portion 804 is the minimum (0%). The illuminance of the dimmed portion 802 is controlled according to the target present there, and is set to 20% in this example.

FIG. 30B shows the luminance of the semiconductor light source, that is, the time waveform of the pulse dimming signal PWM_DIM. In the non-dimming portion 806, the duty cycle is 100%, in the light-shielding portion 804 it is 0%, and in the dimming portion 802 it is 20%.

FIG. 30 (c) shows the dimmed portion 802 in an enlarged manner. As in the pulse dimming signal PWM_DIM of FIG. 30B, when the phase of PWM dimming is fixed to be constant over a plurality of continuous scans, the same portion is continuously irradiated in the horizontal direction. Vertical stripes 803 appear. The vertical stripes 803 have an unfavorable effect such as making the sign 810 difficult to see.

Below, we will explain the technique for suppressing such vertical stripes. FIG. 31 is a block diagram of the vehicle lamp 100E according to the embodiment. The vehicle lamp 100E includes a scanning light source 200A and a lighting circuit 300E. The basic configuration of the lighting circuit 300E is the same as that of the lighting circuit 300A of FIG. The PWM signal generation unit 310E has a phase shift function, and changes the phase of the pulse dimming signal PWM_DIM_E for each scan by the scanning light source 200A. The microcontroller 304 and the LED driver 320 may be mounted on one substrate or may be arranged in one housing.

The method of PWM dimming by the LED driver 320 is not particularly limited, and may be one using the above-mentioned series switch 323 or one using a bypass switch parallel to the light source.

32 (a) to 32 (c) are diagrams illustrating an example of the operation of the vehicle lamp 100E. FIG. 32A shows an example of the phase shift of the pulse dimming signal PWM_DIM_E. FIG. 32 (b) shows a part of the waveform of the pulse dimming signal PWM_DIM_E over a plurality of continuous scanning cycles corresponding to the dimmed portion. The PWM signal generation unit 310E shifts the phase of the pulse dimming signal PWM_DIM_E by 180 ° (half cycle T _PWM / 2 of the PWM cycle) for each scan.

FIG. 32 (b) is a diagram showing the dimming distribution of the dimming portion 802 corresponding to the pulse dimming signal PWM_DIM_E of FIG. 32 (a). When a phase shift of 180 degrees is given, the interval of the vertical stripes 803'is 1/2 times the interval of the vertical stripes 803 in FIG. 30.

The solid line (i) in FIG. 32 (c) shows the illuminance distribution of the dimmed portion 802. For comparison, the illuminance distribution of the same dimmed portion 802 in FIG. 30 (c) is shown by the alternate long and short dash line (ii). The illuminance (time average) of the vertical stripes 803'is 1/2 times the illuminance of the vertical stripes 803 of FIG. 30 (c).

Since the contrast of the vertical stripes 803'is lower than the contrast of the vertical stripes 803', it becomes difficult to see the vertical stripes 803'by the human eye or a camera. As a result, the label 810 is easy to see or identify.

33 (a) to 33 (c) are diagrams illustrating an example of the operation of the vehicle lamp 100E. FIG. 33 (a) shows another example of the phase shift of the pulse dimming signal PWM_DIM_E. FIG. 33 (b) shows a part of the waveform of the pulse dimming signal PWM_DIM_E over a plurality of continuous scanning cycles corresponding to the dimmed portion. In this example, the PWM signal generation unit 310E shifts the phase of the pulse dimming signal PWM_DIM_E by 360 ° / N (half cycle T _PWM / N of the PWM cycle) for each N scan. In this example, the case of N = 3 is shown.

FIG. 33 (b) is a diagram showing the light distribution of the dimming portion 802 corresponding to the pulse dimming signal PWM_DIM_E of FIG. 33 (a). When a phase shift of 360 ° / N = 120 ° is given for each scan, the interval of the vertical stripes 803'is 1 / N times the interval of the vertical stripes 803 in FIG. 30.

The solid line (i) in FIG. 33 (c) shows the illuminance distribution of the dimmed portion 802. For comparison, the illuminance distribution of the same dimmed portion 802 in FIG. 30 (c) is shown by the alternate long and short dash line (ii). The illuminance (time average) of the vertical stripes 803 "is 1 / N times the illuminance of the vertical stripes 803 in FIG. 30 (c).

Since the contrast of the vertical stripes 803 is lower than that of the vertical stripes 803, the vertical stripes 803'are difficult to see by the human eye or a camera. As a result, the sign 810 is easy to see or identify.

FIG. 34 is a block diagram showing a configuration example of the PWM signal generation unit 310E. As described above, the PWM signal generation unit 310E can be implemented as a microcontroller, and therefore each block represents a function or process of the PWM signal generation unit 310E.

The PWM signal generation unit 310E includes a carrier signal generator 312, a duty cycle controller 314, and a comparator 316. The carrier signal generator 312 generates a periodic carrier signal S11 of a triangular wave or a sawtooth wave in synchronization with the position detection signal S4. The carrier signal generator 312 changes the phase of the carrier signal S11 for each scanning cycle. The carrier signal generator 312 can be configured by, for example, a counter, and the timing of starting the operation of the counter may be shifted for each scanning cycle.

The duty cycle controller 314 receives the light distribution pattern information S3 and the position detection signal S4, and outputs the duty cycle command value S12 at each scanning position for each PWM cycle T _PWM .

The comparator 316 compares the command value S12 of the duty cycle with the carrier signal S11, and outputs a pulse dimming signal PWM_DIM_E according to the comparison result.

FIG. 35 is an operation waveform diagram of the PWM signal generation unit 310E of FIG. 34. The PWM signal generation unit 310E starts the scan cycle _TSCAN with the assertion of the position detection signal S4 as a trigger. The light distribution pattern information S3 is the command value S12 of the duty cycle for each PWM cycle.
To update.

The carrier signal generator 312 generates the sawtooth wave carrier signal S11. The phase of the carrier signal S11 is shifted by 180 ° in each scanning cycle. The phase of the pulse dimming signal PWM_DIM_E based on the comparison result of the carrier signal S11 and the duty cycle command value S12 changes by 180 ° for each scanning cycle.

Note that the configuration of the PWM signal generation unit 310E is not limited to FIG. 34, and its operation is not limited to FIG. 35.

(Modification 1)
In the first modification, the PWM signal generation unit 310E inverts the polarity of the carrier signal S11 for each scanning cycle. FIG. 36 is an operation waveform diagram of the PWM signal generation unit 310E according to the first modification. Also by this method, the phase of the pulse dimming signal PWM_DIM_E can be shifted for each scan.

(Modification 2)
In FIG. 33, the phase is delayed by 360 ° / N for each scanning cycle, but the phase may be advanced by 360 ° / N for each scanning cycle. Alternatively, the phase may be randomly changed for each scanning cycle.

(Initialized lighting)
As described above, the abnormality detection circuit 370 makes it a condition for abnormality determination that the output voltage V _OUT of the buck converter 322 deviates from a predetermined voltage range. Since the output voltage V _OUT of the buck converter 322 rises from 0V during the period when the buck converter 322 is switched and the series switch 323 is on, the output voltage V _OUT deviates from the predetermined voltage range immediately after the start of lighting. ing. That is, immediately after the start of lighting, a short circuit abnormality of the series switch cannot be detected. To solve this problem, initialize lighting is introduced.

FIG. 37 is a block diagram of a vehicle lighting device 100G that supports initialization lighting. An ignition signal IG is input to the vehicle lamp 100G in addition to the lighting command LAMP_ON. The vehicle lamp 100G is set to the initialization mode by using the ignition on as a trigger. The mode of the vehicle lamp 100G can be managed by the microcontroller 304G, and the function related to the mode management is shown as the mode control unit 314. When the microcontroller 304G detects the ignition on, it shifts to the initialization mode and instructs the lighting circuit 300G to start lighting even though the lighting command LAMP_ON is not input (referred to as initialization lighting). In the initialized lighting, the light distribution pattern information S3 is not input, or even if it is input, it can be ignored.

In addition, the rotation of the motor 222 starts with the ignition on as a trigger.

When the lighting circuit 300G receives an instruction for initialization lighting from the mode control unit 314, it drives the semiconductor light source 212 and raises the output voltage V _OUT of the buck converter 322 to a specified voltage, that is, Vf. At this time, since the current I _LED flows through the semiconductor light source 212, the semiconductor light source 212 emits light.

The lighting circuit 300G drives the semiconductor light source 212 with a brightness that cannot be visually recognized from the surroundings in the initialized lighting. As a result, the initialization can be completed without being noticed by the people around. In the initialized lighting, the semiconductor light source 212 may be lit with a very low duty cycle in order to illuminate with a brightness that cannot be visually recognized from the surroundings (PWM dimming). For example, upon receiving an instruction for initialization lighting, the PWM signal generation unit 310 may generate a pulse dimming signal PWM_DIM having a predetermined duty cycle in synchronization with the position detection signal S4 and supply it to the LED driver 320. The duty cycle at this time may be 5% or less, and for example, the duty cycle may be the minimum value (corresponding to 1LSB). The pulse dimming signal PWM_DIM in the initialized lighting is irrelevant to the light distribution pattern information S3.

The above is the configuration of the vehicle lighting equipment 100G. Next, the operation will be described. FIG. 38 is an operation waveform diagram of the vehicle lamp 100G of FIG. 37.

At time t ₀ , the ignition signal IG_ON becomes high, and the ignition on is notified. With this as a trigger, the lighting circuit 300G starts the rotation of the motor 222. When the rotation speed of the motor 222 reaches a predetermined value (for example, 6000 rpm), the initialization lighting is started. Initialized lighting produces a pulse dimming signal PWM_DIM with a very small duty cycle. The LED driver 320 operates intermittently in response to the pulse dimming signal PWM_DIM. As a result, the drive current I _LED having a very short time width is supplied to the semiconductor light source 212, and the output voltage V _OUT of the LED driver 320 (output voltage V _OUT of the buck converter 322) increases with time. _When the output voltage V _OUT reaches the specified voltage at time t2, the initialization lighting ends and the standby state is set.

Then, when the lighting command _{LAMP_ON} is asserted at time t3, the PWM signal generation unit 310 generates a pulse dimming signal PWM_DIM corresponding to the light distribution pattern information S3.

At the time of asserting the lighting command LAMP_ON, the initialization lighting is completed, and the output voltage V _OUT of the LED driver 320 has reached the specified voltage, so that the lighting can be started immediately.

Further, since the output voltage V _OUT of the LED driver 320 has risen to the specified voltage when the lamp lighting command is received after the initialization mode is completed, the abnormality detection circuit 370 can immediately start the abnormality detection.

Next, a modified example of the initialization mode will be explained.

(Modification 1)
In the initialization mode, PWM dimming is used to make the semiconductor light source 212 emit light so as not to be seen from the surroundings, but analog dimming (DC dimming) may be used instead of or in addition to it. In the lighting circuit 300G according to the first modification, the current amount of the drive current I _LED may be reduced in the initialization mode as compared with the normal lighting. This makes it difficult to see from the surroundings.

(Modification 2)
Similar to FIG. 16, the vehicle lamp 100G may include a plurality of semiconductor light sources 212_1 to 212_N (N ≧ 2) and a plurality of LED drivers 320_1 to 320_N corresponding thereto. A plurality of semiconductor light sources 212_1 to 212_N are scanned and combined on a virtual vertical screen to form a light distribution.

In this modification 2, the on timing of the plurality of pulse dimming signals PWM_DIM_1 to PWM_DIM_N supplied to the plurality of LED drivers 320_1 to 320_N may be shifted.

FIG. 39 is an operation waveform diagram of the vehicle lamp 100G according to the second modification. According to the second modification, it is possible to prevent a plurality of semiconductor light sources 212_1 to 212_N from lighting at the same time during the PWM cycle, and it is possible to make it difficult to see from the surroundings.

(Modification 3)
In the above description, the initialization lighting is performed in such a manner that it cannot be visually recognized from the surroundings, but it may be positively emitted as an effect. In this case, if the semiconductor light source 212 is flashed halfway, it will be confused with a failure or abnormality. Therefore, in the third modification, the initialized lighting is turned on for a certain long time, for example, several hundred ms to several seconds, so that it can be recognized that the initial lighting is not a failure.

When the semiconductor light source 212 is a light source for a high beam, it is not preferable because the upper side of the cut line is irradiated. Therefore, the vehicle lamp 100G may further include a leveling device that controls the optical axis of the scanning light source 200 in the pitch direction. In the initialization mode, the leveling device may lower the optical axis of the scanning light source. As a result, the emitted light during the initialization lighting can be radiated downward as much as possible.

(Modification example 4)
In the description so far, the microcontroller 304G of the lighting circuit 300G controls the initialization lighting, but the light distribution controller (ADB ECU) 400 may control the initialization lighting. In this case, the light distribution controller 400 monitors the ignition signal IG_ON and shifts to the initialization mode when the ignition is turned on. Then, when the mode shifts to the initialize mode, the light distribution pattern information S3 corresponding to the initialize lighting is generated.

(Modification 5)
In the above description, the abnormality detection circuit 370 has determined to detect a short circuit of the series switch 323 based on the output voltage V _OUT of the buck converter 322, but this is not the case. For example, the abnormality detection circuit 370 may detect an open abnormality in place of or in addition to the short circuit of the series switch 323. Alternatively, an abnormality (ground fault, heaven fault, etc.) other than the series switch 323 may be monitored, and the present disclosure is applicable as long as the abnormality is detected based on the output voltage V _OUT of the buck converter 322.

Although the present disclosure has been described using specific terms and phrases based on the embodiments, the embodiments merely indicate the principles and applications of the present disclosure, and the embodiments are defined in the claims. Many modifications and arrangement changes are permitted to the extent that they do not deviate from the ideas of the present disclosure.

S1 ... Sensor information, S2 ... Vehicle information, S3 ... Light distribution pattern information, S4 ... Position detection signal, PWM_DIM ... Pulse dimming signal, 100 ... Vehicle optics, 200 ... Scanning light source, 210 ... Light source unit, 212 ... Semiconductor Light source, 220 ... scanning optical system, 222 ... motor, 224 ... blade mirror, 226 ... mirror spacing, 230 ... projection optical system, 300 ... lighting circuit, 302 ... position detector, 310 ... PWM signal generator, 320 ... LED driver 322 ... Step-down converter, 323 ... Series switch, 324 ... Driver circuit, 326 ... Output circuit, 328 ... Converter controller, 330 ... Transconductance amplifier, 332 ... Sample hold circuit, 334 ... On-time control unit, 336 ... Gate driver, 340 ... control IC, 370 ... abnormality detection circuit, 372 ... comparison circuit, 374 ... signal processing unit, 376 ... mask processing unit, 400 ... light distribution controller, 900 ... virtual vertical screen.

Claims

A scanning light source that includes a semiconductor light source and scans the emitted light of the semiconductor light source over the entire horizontal range of the light distribution.
A lighting circuit that can adjust the amount of light of the semiconductor light source at each scanning position in multiple gradations by pulse modulation in synchronization with the scanning of the scanning type light source.
A vehicle lighting fixture characterized by being equipped with.
In addition to the semiconductor light source, the scanning light source further includes a reflector that receives the emitted light of the semiconductor light source and scans the reflected light in front of the vehicle by repeating a predetermined periodic motion.
The lighting circuit is characterized in that, in synchronization with the motion of the reflector, a control waveform of pulse modulation is generated, and the drive current supplied to the semiconductor light source is switched according to the control waveform. The vehicle lighting equipment described.
The lighting circuit is
A series switch provided in series with the semiconductor light source,
A constant current driver connected to the series connection circuit of the series switch and the semiconductor light source,
Equipped with
The vehicle lamp according to claim 1 or 2, wherein the lighting circuit switches the series switch in a duty cycle according to a scanning position.
The constant current driver
With a switching converter
A converter controller that drives the switching converter so that the detected value of the output current of the switching converter approaches a predetermined target value.
The vehicle lamp according to claim 3, wherein the lamp comprises the above.
Claims 1 to 4 include a plurality of semiconductor light sources, and the scanning type light source scans two or more emitted lights of the plurality of semiconductor light sources over the entire horizontal range of the light distribution. Vehicle lighting equipment described in any of.
The vehicle lighting fixture according to claim 5, wherein the two or more emitted lights are scanned at different heights on a virtual vertical screen.
A scanning light source that includes a semiconductor light source and scans the emitted light of the semiconductor light source,
A lighting circuit that can adjust the amount of light of the semiconductor light source at each scanning position in multiple gradations by pulse modulation in synchronization with the scanning of the scanning type light source.
Equipped with
The lighting circuit is a vehicle lighting device characterized in that the phase of pulse modulation is changed for each scan.
The vehicle lamp according to claim 7, wherein the lighting circuit shifts the phase of pulse modulation by 180 ° for each scan.
The vehicle lamp according to claim 7, wherein the lighting circuit shifts the phase of pulse modulation by 360 ° / N (N ≧ 3) for each scan.
The lighting circuit is
A series switch provided in series with the semiconductor light source,
A constant current output buck converter that is connected to the series switch and the series connection circuit of the semiconductor light source to generate a drive current.
A dimming signal generator that generates a pulse-modulated pulse dimming signal whose phase shifts with each scan,
A driver circuit that drives the series switch based on the pulse dimming signal,
The vehicle lamp according to any one of claims 7 to 9, wherein the lamp is provided with.
The lighting circuit is
Generates a periodic carrier signal whose phase changes with each scan,
A duty cycle command value is generated for each pulse cycle.
The duty cycle command value is compared with the carrier signal to generate a pulse dimming signal.
The vehicle lamp according to any one of claims 7 to 10, wherein the drive current flowing through the semiconductor light source is switched based on the pulse dimming signal.
A scanning light source that includes a semiconductor light source and scans the emitted light of the semiconductor light source,
A constant current driver that controls the drive current supplied to the semiconductor light source in synchronization with the scanning of the scanning light source and controls the amount of light of the semiconductor light source.
Equipped with
The constant current driver
A series switch provided in series with the semiconductor light source,
It is connected to the series connection circuit of the series switch and the semiconductor light source, (i) outputs a constant current during the on period of the series switch, (ii) stops the switching operation during the off period of the series switch, and immediately before. With a buck converter that maintains substantially the same output voltage as the on period,
The driver circuit that drives the series switch based on the pulse dimming signal,
An abnormality detection circuit that detects an abnormality based on the output voltage of the buck converter,
Equipped with
A vehicle lighting fixture characterized in that the constant current driver drives the semiconductor light source and executes initialization lighting that raises the output voltage of the buck converter to a specified voltage by using an ignition on as a trigger.
The vehicle lamp according to claim 12, wherein the abnormality detection circuit determines that the series switch is abnormal when the output voltage of the buck converter deviates from the normal range during the off period of the series switch. ..
The vehicle lamp according to claim 12 or 13, wherein the constant current driver drives the semiconductor light source with a brightness that cannot be visually recognized from the surroundings.
The vehicle lamp according to claim 12 or 13, wherein the constant current driver lights the semiconductor light source with a brightness that can be visually recognized from the surroundings in the initialized lighting.
A leveling device for controlling the optical axis of the scanning light source in the pitch direction is further provided.
The vehicle lamp according to claim 15, wherein in the initialized lighting, the leveling device lowers the optical axis of the scanning light source.
The vehicle lamp according to any one of claims 12 to 16, wherein the constant current driver reduces the duty cycle of the pulse dimming signal to 5% or less in the initialized lighting.
The scanning light source includes a plurality of the semiconductor light sources.
There are a plurality of constant current drivers corresponding to the plurality of semiconductor light sources.
The vehicle lighting device according to any one of claims 12 to 17, wherein the plurality of pulse dimming signals supplied to the plurality of constant current drivers are turned on at different timings.
The vehicle lamp according to any one of claims 12 to 18, wherein the constant current driver reduces the amount of current of the drive current in the initialized lighting as compared with the case of normal lighting.
A scanning light source that includes a semiconductor light source and scans the emitted light of the semiconductor light source,
A constant current driver that controls the drive current supplied to the semiconductor light source in synchronization with the scanning of the scanning light source and controls the amount of light of the semiconductor light source.
Equipped with
The constant current driver
A series switch provided in series with the semiconductor light source,
It is connected to the series connection circuit of the series switch and the semiconductor light source, (i) outputs a constant current during the on period of the series switch, (ii) stops the switching operation during the off period of the series switch, and immediately before. With a buck converter that maintains substantially the same output voltage as the on period,
The driver circuit that drives the series switch based on the pulse dimming signal,
An abnormality detection circuit that detects an abnormality based on the output voltage of the buck converter,
A mask processing unit that masks the detection result of the abnormality detection circuit while the cumulative lighting time obtained by integrating the product of the duty cycle of the pulse dimming signal and the lighting time is lower than a predetermined threshold value.
A lighting fixture for vehicles characterized by being equipped with.
The vehicle lamp according to claim 20, wherein the mask processing unit weights the lighting time with a power supply voltage supplied to the vehicle lamp and integrates the lighting time.
20 or 21, wherein the mask processing unit changes the threshold value according to at least one of a power supply voltage supplied to the vehicle lamp and a scanning cycle of the scanning light source. The vehicle lighting equipment described.
The abnormality detection circuit according to any one of claims 20 to 22, wherein when the output voltage of the buck converter deviates from the normal range during the off period of the series switch, the abnormality detection circuit determines that the series switch is abnormal. The vehicle lighting equipment described.
The vehicle lighting device according to any one of claims 20 to 22, wherein the pulse dimming signal generation circuit for generating the pulse dimming signal and the mask processing unit are mounted on the same microcontroller.