Lighting circuit and vehicle lamp

Abstract

The present invention is provided with: a drive circuit for supplying a drive current to a light source; and a control circuit that includes a storage unit that stores first information relating to the drive current in a light-increasing mode in which the brightness of the light source after being turned off gradually becomes a first brightness, and second information relating to the drive current in a first light-decreasing mode in which the brightness of the light source after being turned off gradually becomes a second brightness, and that controls the drive circuit, the storage unit storing first information relating to the drive current in a light-decreasing mode in which the brightness of the light source after being turned off gradually becomes a second brightness. In the first dimming mode, the brightness of the light source is gradually darkened from the first brightness to extinguish the light source, and the control circuit controls the driving circuit by using the first information and the second information based on a first instruction, so that the light source is extinguished in the first dimming mode after being lightened in the intensifying mode, and the light source is extinguished in the second dimming mode after being lightened in the intensifying mode. On the basis of a second instruction, the drive circuit is controlled by a part of the second information so that the light source is turned off in a second dimming mode in which the brightness of the light source is gradually darker from a second brightness that is darker than the first brightness and the light source is turned off.

Description

Lighting circuits and vehicle lights Technical Field

[0001] This invention relates to lighting circuits and vehicle lamps. Background Technology

[0002] As a lighting circuit applied to vehicle lamps, for example, Patent Document 1 discloses a lighting circuit that adjusts the brightness of the light source by simultaneously employing the following controls: control that adjusts the magnitude of the drive current using a switching element (DC dimming), and PWM control of a switch installed on the supply path that supplies the drive current to the light source. Furthermore, Patent Document 1 discloses that the brightness of the light source changes smoothly (gradually) by using a table (information) that establishes a correspondence between conditions (duty cycle) related to the drive current and the dimming rate.

[0003] Prior art literature, patent literature, patent literature 1: Japanese Patent Application Publication No. 2013-258003 Summary of the Invention

[0004] (a) Technical problems to be solved However, in cases where there are multiple controls that gradually change the brightness of the light source depending on the conditions under which the light source is lit (e.g., dimming mode), it is necessary to prepare tables for each type of control, which is a heavy development burden.

[0005] The purpose of this invention is to provide a lighting circuit that can reduce the development burden.

[0006] (II) Technical Solution The main purpose of this invention is to achieve the stated objective. It is a lighting circuit comprising: a driving circuit that supplies a driving current to a light source; and a control circuit that includes a storage unit and controls the driving circuit. The storage unit stores first information related to the driving current in a brightness enhancement mode and second information related to the driving current in a first brightness reduction mode. In the brightness enhancement mode, the brightness of the light source after it is turned off gradually becomes a first brightness. In the first brightness reduction mode, the brightness of the light source gradually dims from the first brightness to turn off the light source. Based on a first instruction, the control circuit controls the driving circuit using the first information and the second information to cause the light source to be turned on in the brightness enhancement mode and then turned off in the first brightness reduction mode. Based on a second instruction, the control circuit controls the driving circuit using a portion of the second information to cause the light source to turn off in a second brightness reduction mode, wherein the second brightness reduction mode causes the brightness of the light source to gradually dim from a second brightness that is darker than the first brightness to turn off the light source.

[0007] (iii) Beneficial effects According to the present invention, a lighting circuit that can reduce the development burden can be provided. Attached Figure Description

[0008] Figure 1 is a schematic circuit diagram of the vehicle lamp 1 according to this embodiment.

[0009] Figure 2 is an illustration of the signal conditions under each lighting mode.

[0010] Figure 3 is an explanatory diagram of the welcome lighting mode.

[0011] Figure 4 is an explanatory diagram of the gradually lit table T1 and the gradually turned-off table T2 in the welcome mode.

[0012] Figure 5 is an explanatory diagram of the "Say Goodbye to Light-Up Mode".

[0013] Figure 6 is an illustration of the table (part of table T2) in the welcome mode with the gradual extinguishing of the dial. Detailed Implementation

[0014] <Cross Reference to Related Applications> This application claims priority based on Japanese Patent Application No. 2023-174145, filed on October 6, 2023, and incorporates its contents.

[0015] Based on this specification and the accompanying drawings, at least the following are obvious.

[0016] Furthermore, in this embodiment, unless otherwise specified, "connection" refers to an electrical connection. Therefore, "connection" includes not only the case where two components are connected via wiring, but also, for example, the case where they are connected via a resistor.

[0017] === ...

[0018] The vehicle lamp 1 of this embodiment includes a light source 3 and a lighting circuit 10.

[0019] Light source 3 is illuminated by a drive current Ik supplied by the lighting circuit 10, described later. In this embodiment, light source 3 is used for daytime running lights (DRLs) and parking lights (CLLs). DRLs are lights illuminated during the day to inform pedestrians and drivers of oncoming vehicles of the presence of a moving vehicle. CLLs are lights used to indicate the width of a vehicle and its presence; they are also called parking lights or side marker lights. As described later, DRLs are illuminated more brightly than CLLs.

[0020] The light source 3 includes light-emitting elements D1 to D4 and resistors R1 and R2. Light-emitting elements D1 and D2 and resistor R1 are connected in series with light-emitting elements D3 and D4 and resistor R2, respectively. In addition, the series-connected light-emitting elements D1 and D2 and resistor R1 and the series-connected light-emitting elements D3 and D4 and resistor R2 are connected in parallel between the driving circuit 13 of the lighting circuit 10 and the grounding component.

[0021] In this embodiment, the light-emitting elements D1 to D4 are light-emitting diodes (LEDs). However, the light-emitting elements D1 to D4 are not limited to LEDs; for example, they can also be other semiconductor light-emitting elements such as laser diodes (LDs) and organic EL devices.

[0022] Resistors R1 and R2 are used to suppress deviations in the current flowing in each branch. For example, if there is a deviation in the forward voltage drop of the light-emitting elements D1~D4, the current flowing in the two parallel paths (in other words, the brightness) will also be affected. By setting resistors R1 and R2, such deviations can be suppressed.

[0023] Furthermore, in this embodiment, the light source 3, as described above, is configured with two sets of parallel connections (two parallel connections) for the combination of two series-connected light-emitting elements and resistors, but it is not limited to this. For example, it may be only one series connection, or it may be three or more parallel connections. In addition, each branch may have one or more light-emitting elements.

[0024] Furthermore, although not illustrated, the vehicle lamp 1 of this embodiment also includes a low beam (Lo) light source and a high beam (Hi) light source. Moreover, each light source is illuminated by a drive current Ik supplied by the drive circuit 13 of the lighting circuit 10, which will be described later. Therefore, the lighting circuit 10 of this embodiment is configured to adjust the magnitude and duration of the drive current Ik supplied to the light source according to the lighting mode (details will be described later). For example, when the light source 3 of this embodiment is illuminated as a CLL, shortening the duration of the drive current Ik supplied to the light source 3 (effectively reducing the current) results in a lower brightness than in the DRL case.

[0025] The lighting circuit 10 controls the lighting and extinguishing of each light source (light source 3 in this embodiment) of the vehicle lamp 1. The lighting circuit 10 is supplied with a power supply voltage Vbat (hereinafter also simply referred to as voltage Vbat) from the vehicle battery 2 and receives a CXPI (Clock Extension Peripheral Interface) signal from the vehicle's ECU 100. Furthermore, CXPI is a communication method that follows the vehicle communication protocol established by the Japan Automobile Manufacturers Association (JAMA) for the purpose of reducing wiring harnesses and multiplexing. Moreover, based on the power from the battery 2, the lighting circuit 10 outputs a drive current Ik to the light source (here, light source 3) according to the instruction (CXPI signal) from the ECU 100, causing the light source 3 to light up (the structure of the lighting circuit 10 will be described later).

[0026] The vehicle's ECU 100 outputs a CXPI signal to the lighting circuit 10, corresponding to the user's operating status, etc. Here, "operation" refers to the operation of illuminating the light source 3 in any lighting mode. This "operation" is not limited to the user operating a part of the vehicle (e.g., an indicator), but also includes keyless operation of the vehicle, unlocking and locking of doors by bringing the smart key near the vehicle, etc.

[0027] Furthermore, "keyless" refers to a device that can remotely unlock or lock, for example, vehicle doors. Additionally, "smart key" refers to a device that, for example, instructs the vehicle to unlock its doors if the user is within a designated area of ​​the vehicle.

[0028] The structure of the lighting circuit 10 is shown in Figure 1. The lighting circuit 10 includes a VCC circuit 11, a drive circuit 13, an IF (Interface) circuit 15, a microcontroller 17, a PMOS transistor Q1, and an NMOS transistor Q2.

[0029] PMOS transistor Q1 is positioned between the driving circuit 13 and the light source 3, and NMOS transistor Q2 is positioned between the light source 3 and the ground. Furthermore, microcontroller 17 applies signal S1 to the gate of PMOS transistor Q1 and signal S2 to the gate of NMOS transistor Q2. When the light source 3 is lit, microcontroller 17 sets signal S1 to a low level and signal S2 to a high level. This turns on PMOS transistor Q1 and NMOS transistor Q2, and the driving current Ik output from the driving circuit 13 flows through the light-emitting elements D1 and D2 and resistor R1 of the light source 3, and through the light-emitting elements D3 and D4 and resistor R2, to the ground.

[0030] In addition, although detailed descriptions are omitted, the low beam (Lo) and high beam (Hi) lights (light sources) are also configured in the same way, and the current path is switched by the control of the bypass switch (PMOS transistor), so that the drive current Ik is supplied from the drive circuit 13 to light them up respectively.

[0031] VCC circuit 11 is a power supply circuit that generates a specified level (e.g., 5V) of voltage VCC from voltage Vbat (e.g., 12V) to operate the various circuits (e.g., microcontroller 17) of lighting circuit 10.

[0032] The driving circuit 13 converts the input voltage Vbat into an output voltage corresponding to the light source 3 and generates a driving current Ik, which is supplied to the light source 3. As shown in FIG1, the driving circuit 13 of this embodiment includes a current output circuit 131 and a dimming switch 132.

[0033] The current output circuit 131 includes a switching element 131a (e.g., a MOS transistor) and a switching control circuit 131b.

[0034] The switch control circuit 131b controls the switching element 131a to turn on and off (switch) according to the control signal Sb input from the microcontroller 17. Furthermore, the detection result of the drive current Ik is input to the microcontroller 17 via a current detection circuit (not shown). Moreover, the switch control circuit 131b controls the switching of the switch element 131a based on the control signal Sb input from the microcontroller to make the drive current Ik reach the target value.

[0035] Based on this switch, the current output circuit 131 generates and outputs a drive current Ik corresponding to the control signal Sb. Furthermore, the current output circuit 131 is equivalent to an "output circuit". In this embodiment, the switching frequency of the current output circuit 131 is, for example, 280 kHz (the frequency of the control signal Sb is approximately 10 kHz), which is higher than the PWM control frequency of the dimming switch 132 described later.

[0036] Furthermore, the duty cycle of the control signal Sb represents the rate of decrease (attenuation rate) of the drive current Ik. For example, when the duty cycle of the control signal Sb is 0%, the drive current Ik output from the current output circuit 131 is at its maximum; as the duty cycle of the control signal Sb increases, the drive current Ik decreases. This duty cycle does not represent the actual proportion at which the switching element 131a is turned on. Therefore, even if the duty cycle of the control signal Sb is 0%, the switching element 131a will not be fixedly turned on or off. Specifically, the 280kHz duty cycle is fixed, and only the 10kHz duty cycle varies.

[0037] A dimming switch 132 is located between the current output circuit 131 and the light source 3, and its on / off state is controlled by a PWM signal Sa from the microcontroller 17. If the dimming switch 132 is on, a drive current Ik is supplied to the light source 3. If the dimming switch 132 is off, no drive current Ik is supplied to the light source 3.

[0038] The PWM signal Sa is a rectangular wave (pulse) signal used to make the light source 3 blink at a high speed (e.g., 200Hz). According to the duty cycle of the PWM signal Sa, the dimming switch 132 is turned on and off to adjust the brightness of the light source 3.

[0039] Furthermore, the duty cycle of the PWM signal Sa is the proportion of the period in one cycle of the PWM signal Sa that is at a high level (hereinafter referred to as the H level). The length of the H level period of the PWM signal Sa is substantially equal to the length of the period during which the drive current Ik is supplied to the light source 3. Similarly, the length of the low level period (hereinafter referred to as the L level) of the PWM signal Sa is substantially equal to the length of the period during which the drive current Ik is not supplied to the light source 3. Therefore, if the duty cycle of the PWM signal Sa increases, the proportion of the period during which the drive current Ik is supplied to the light source 3 increases (the light source 3 becomes brighter). Conversely, if the duty cycle of the PWM signal Sa decreases, the proportion of the period during which the drive current Ik is not supplied to the light source 3 increases (the light source 3 becomes dimmer).

[0040] IF circuit 15 is a device (CXPI transceiver) used for CXPI communication with the vehicle's ECU 100.

[0041] If the IF circuit 15 receives a CXPI signal from the vehicle's ECU 100, it demodulates the received signal and sends it as an indication signal to the microcontroller 17. In this embodiment, the CXPI signal includes a DRL signal indicating the on / off state of the DRL, a CLL signal indicating the on / off state of the CLL, and a WEL signal indicating gradual on / off (described later). Furthermore, the communication method is not limited to CXPI and can also be other communication methods (e.g., CAN communication, LIN communication).

[0042] The microcontroller 17 operates when a voltage VCC is applied, controlling various circuits (e.g., the drive circuit 13) of the lighting circuit 10. The microcontroller 17 includes a storage unit 171 and an arithmetic processing unit 172. Furthermore, the microcontroller 17 is equivalent to a "control circuit".

[0043] The storage unit 171 includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and stores programs executed (processed) by the arithmetic processing unit 172, various information (tables described later) for controlling the lighting of the light source 3, and the like.

[0044] The arithmetic processing unit 172 is, for example, a CPU (Central Processing Unit), and realizes various functions by executing the programs stored in the storage unit 171.

[0045] In the present embodiment, the microcontroller 17 determines the values (duty ratios) of the PWM signal Sa and the control signal Sb based on the instruction signal received via the IF circuit 15 and the information stored in the storage unit 171, etc., and outputs them to the drive circuit 13. Thereby, a drive current Ik is generated in the drive circuit 13, and the current supplied to the light source 3 is adjusted.

[0046] More specifically, the microcontroller 17 sets the duty ratio of the control signal Sb according to the lighting mode, controls the conduction and disconnection of the switching element 131a, and adjusts the magnitude of the drive current Ik. In addition, the microcontroller 17 controls the conduction and disconnection of the dimming switch 132 by the duty ratio of the PWM signal Sa, and adjusts the ratio of the period during which the drive current Ik is supplied to the light source 3. Thereby, the brightness of the light source 3 is adjusted.

[0047] <<Operation of the lighting circuit 10>> The lighting circuit 10 lights the light source 3 based on the instruction of the CXPI signal received from the vehicle's ECU 100. In the vehicle lamp 1 of the present embodiment, as the lighting mode of the light source 3, there are four modes (DRL lighting mode, CLL lighting mode, welcome lighting mode, farewell lighting mode).

[0048] FIG. 2 is an explanatory diagram of the signal conditions in each lighting mode. In addition, in FIG. 2, the ON of the signal S1 is represented as "L level" (the OFF is represented as "H level"). In addition, the ON of the WEL signal, DRL signal, WEL signal, and signal S2 is represented as "H level", and the OFF is represented as "L level". For example, when lighting the light source 3, the signal S1 becomes the L level and the signal S2 becomes the H level. Thereby, both the PMOS transistor Q1 and the NMOS transistor Q2 become conductive, and the light source 3 becomes a lit state. In addition, in FIG. 2, the values (%) of the PWM signal Sa and the control signal Sb represent the duty ratio.

[0049] <DRL lighting mode> As described above, the DRL lighting mode is a mode in which the light source 3 is lit to inform pedestrians, drivers of oncoming vehicles, etc. of the presence of the vehicle during the day.

[0050] When the light source 3 is lit as DRL, as shown in FIG. 2, the DRL signal becomes ON (H level), and the CLL signal and the WEL signal become OFF (L level). The indication (indication signal) at this time corresponds to the "fourth indication". In this case, the microcontroller 17 sets the duty ratio of the PWM signal Sa to 100% and sets the duty ratio (dimming rate) of the control signal Sb to 0%.

[0051] When the duty ratio (dimming rate) of the control signal Sb is 0% and the dimming switch 132 is turned on, the current value of the drive current Ik output from the current output circuit 131 corresponds to the "specified value". In addition, the duty ratio of the PWM signal Sa becomes 100%, whereby the dimming switch 132 is fixed to be turned on (the conduction period is the longest). Therefore, the light source 3 is lit brightly. In addition, the duty ratio (100%) of the PWM signal Sa at this time corresponds to the "third duty ratio".

[0052] <CLL lighting mode>As described above, the CLL lighting mode is a mode in which the light source 3 is lit to indicate the size and presence of the vehicle in the width direction. In addition, the CLL lighting mode corresponds to the "lighting mode".

[0053] When the light source 3 is lit as CLL, the CLL signal becomes ON (H level), and the DRL signal and the WEL signal are OFF (L level). The indication (indication signal) at this time corresponds to the "third indication". In this case, the microcontroller 17 sets the duty ratio of the PWM signal Sa to 7% and sets the duty ratio of the control signal Sb to 0%. The drive current Ik output from the current output circuit 131 is the same as in the DRL lighting mode, but since the duty ratio of the PWM signal Sa is small (the time for supplying the drive current Ik to the light source 3 is short), the light source 3 is lit with a lower brightness (i.e., dimly) compared to the case of DRL lighting. In addition, the duty ratio (7%) of the PWM signal Sa at this time corresponds to the "second duty ratio".

[0054] <Welcome lighting mode>The welcome lighting mode is a mode in which the light source 3 is lit, for example, when the door of the vehicle is unlocked. In the welcome lighting mode of the present embodiment, first, a gradual lighting from the extinguished state to a brighter state is performed, and after lighting while maintaining a certain brightness, a gradual dimming is performed. In addition, the gradual lighting in the welcome lighting mode corresponds to the "light increasing mode", and the gradual dimming corresponds to the "first light dimming mode". Such gradual lighting and gradual dimming are performed based on a table stored in the storage unit 171 of the microcontroller 17.

[0055] Figure 3 is an explanatory diagram of the welcome lighting mode. From top to bottom, Figure 3 shows the indicator signals (CLL, WEL), PWM signal Sa, control signal Sb, and current (drive current Ik). The horizontal axis of each graph in Figure 3 represents time (sec). Figure 4 is an explanatory diagram of table T1 for gradual lighting and table T2 for gradual extinguishing in the welcome mode. In each table, the values ​​of PWM signal Sa (duty cycle), control signal Sb (duty cycle), and drive current Ik are correlated according to time (elapsed time). Table T1 corresponds to "first information," and table T2 corresponds to "second information."

[0056] The following description, with reference to Figures 2, 3, and 4, explains the welcome lighting mode.

[0057] In the initial state, the CLL signal, WEL signal (and DRL signal) are all at L level. In addition, according to Figure 3, at this time, the duty cycle of the PWM signal Sa is 0% (the dimming switch 132 is fixed to be off), the duty cycle of the control signal Sb is 100%, and the drive current Ik is 0mA (that is, the light source 3 is off).

[0058] For example, when the vehicle door is unlocked, at time t1, both the CLL and WEL signals change to H level, switching to the welcome lighting mode. Furthermore, the indication (indication signal) for executing the welcome lighting mode at this time is equivalent to the "first indication".

[0059] Initially, referring to the gradually lit table T1 shown in Figure 4, the microcontroller 17 sets the duty cycle of the PWM signal Sa to 30% and the duty cycle of the control signal Sb to 67%. At this time, the drive current Ik becomes 160mA, and the light source 3 is lit. In addition, the duty cycle (30%) of the PWM signal Sa is equivalent to the "first duty cycle".

[0060] Next, referring to the gradually lit table T1 in Figure 4, the microcontroller 17 gradually reduces the duty cycle of the control signal Sb (reducing the light reduction rate) as time passes. As a result, as shown in Figure 3, the drive current Ik gradually increases, and the light source 3 gradually becomes brighter.

[0061] At time t2, 2080 ms after the gradual illumination begins (time t1), the gradual illumination ends. Afterwards, for a specified period (up to time t3: for example, approximately 13 seconds), the duty cycles of the PWM signal Sa and the control signal Sb remain unchanged, and the drive current Ik remains constant (1350mA). Therefore, the brightness of light source 3 is constant. Furthermore, the brightness of light source 3 at this time is equivalent to the "first brightness".

[0062] At time t3, the CLL signal changes from H level to L level. Therefore, the microcontroller 17, referring to the gradual extinguishing table T2 in Figure 4, executes gradual extinguishing.

[0063] That is, similar to the gradual lighting scenario, the microcontroller 17 gradually increases the value (duty cycle) of the control signal Sb over time (the duty cycle of the PWM signal Sa is fixed at 30%). As a result, as shown in Figure 3, the drive current gradually decreases from 1350mA, and the light source 3 gradually dims.

[0064] Then, at time t4, 2080 ms after the start of the gradual extinguishing (time t3), the duty cycle of the control signal Sb becomes 67%, and the gradual extinguishing ends. Afterward, the duty cycle of the control signal Sb becomes 100%, and the light source 3 is extinguished.

[0065] Furthermore, the brightness of light source 3 at time ta (with a duty cycle of 30% for signal Sa and 60% for signal Sb) 1830 ms after time t3 is approximately the same as the brightness in the CLL lighting mode (with a duty cycle of 7% for signal Sa and 0% for signal Sb) (same beam). Additionally, it is approximately the same as the brightness at the start of the farewell lighting mode, described later. The brightness of light source 3 at this time corresponds to the "second brightness," which is dimmer than the brightness at times t2-t3 ("first brightness").

[0066] The <Farewell Lighting Mode> is, for example, a mode in which the light source 3 is illuminated when the driver's seat sensor (not shown) detects that the user has left the vehicle and the driver's seat door is locked within a specified time. In this farewell lighting mode, initially, after the light source 3 is illuminated as a CLL (CLL illumination mode), it gradually dims and then dims. Furthermore, the gradual dimming in the farewell lighting mode is equivalent to a "second dimming mode". The gradual dimming in the farewell mode is also based on a table stored in the storage unit 171 of the microcontroller 17.

[0067] Furthermore, as mentioned above, in CLL lighting mode, the duty cycle of the PWM signal Sa is 7%. Therefore, if the duty cycle of the PWM signal Sa is fixed at 7%, and the control signal Sb is changed to gradually turn off, a new table different from the welcome mode table T2 (the table for gradual fading off) needs to be created, increasing the development burden. In addition, the storage unit 171 needs to store the capacity of the created table.

[0068] Therefore, in this embodiment, the gradual extinguishing of the farewell mode is performed using the table T2 that shows the gradual extinguishing in the welcome lighting mode.

[0069] However, the gradual shutdown of the farewell lighting mode begins from the state where light source 3 is lit as a CLL (CLL lighting mode). Therefore, the brightness (beam) of light source 3 at the start of the gradual shutdown is set to be the same as that of CLL lighting. Specifically, the drive current Ik at the start of the farewell lighting mode is made the same as the drive current Ik (290mA) of CLL lighting mode. That is, in the farewell lighting mode, it is 1830ms after the gradual shutdown of the welcome lighting mode in table T2 (specifically, the times ta~t4 in Figures 3 and 4).

[0070] Figure 5 is an explanatory diagram of the "Farewell to Light" mode. Additionally, Figure 6 is an explanatory diagram of the gradual fading off table (part of table T2) in the "Farewell to Light" mode.

[0071] As described above, for example, when the driver's seat sensor (not shown) detects that the user has left the vehicle and the driver's seat door is locked within a specified time, the goodbye mode is activated.

[0072] Initially, the CLL signal changes to H level, switching to CLL lighting mode. That is, the microcontroller 17 sets the PWM signal Sa to 7% and the control signal Sb to 0%. At this time, the drive current Ik is 290mA.

[0073] At time t5, after a predetermined time (e.g., 16.4 seconds), the WEL signal changes to H level. Thus (specifically, by the CLL signal changing to L level and the WEL signal changing to H level), the microcontroller 17 begins the gradual shutdown process to exit the on / off mode. The indication (indication signal) at this time of executing the gradual shutdown process to exit the on / off mode is equivalent to a "second indication".

[0074] First, referring to the table in Figure 6 (a portion of table T2 in Figure 4), the microcontroller 17 changes the value of the PWM signal Sa (duty cycle) from 7% to 30%, and further changes the value of the control signal Sb from 0% to 60%. The current value at this point is 290mA according to Figure 4, which is equal to the current value when the CLL is lit in Figure 5. Therefore, the brightness of the light source 3 is approximately the same as before time t5.

[0075] Furthermore, referring to the table in Figure 6, the microcontroller 17 gradually increases the duty cycle of the control signal Sb over time. As a result, the brightness of the light source 3 gradually decreases.

[0076] At time t6, 250ms after the gradual extinguishing begins (time t5), the control signal Sb changes to 67%, and the drive current Ik changes to 160mA (the same as time t4 in the welcome lighting mode), ending the gradual extinguishing of the farewell mode. Afterwards, the control signal Sb changes to 100%, and light source 3 turns off.

[0077] As described above, in this embodiment, when the farewell mode fades out, a portion of the welcome mode's fade-out table T2 is used, thus eliminating the need to create a new table for the farewell mode. Therefore, the development burden is reduced. Furthermore, the capacity used to store tables in the storage unit 171 can be reduced.

[0078] ===Summary=== The lighting circuit 10 of this embodiment has been described above. The lighting circuit 10 includes: a drive circuit 13 that supplies a drive current Ik to the light source 3; and a microcontroller 1 that includes a storage unit 171 and controls the drive circuit 13. The storage unit 171 stores a table T1 related to the drive current Ik for gradual lighting (brightness enhancement mode) and a table T2 related to the drive current Ik for gradual extinguishing (first dimming mode). Based on the welcome lighting indication, the microcontroller 17 controls the drive circuit 13 using tables T1 and T2 so that the light source 3 is lit by gradual lighting and then extinguished by gradual extinguishing. Based on the farewell lighting indication, the microcontroller 17 controls the drive circuit 13 using a portion of table T2 so that the light source 3 is extinguished by gradual extinguishing (second dimming mode), wherein the gradual extinguishing (second dimming mode) causes the brightness of the light source 3 to gradually dim from the brightness at CLL to extinguish the light source 3.

[0079] Therefore, there is no longer a need to create a gradient off table for the farewell lighting mode, thus reducing the development burden. In addition, the capacity used to store the table in the storage unit 171 can be reduced.

[0080] In addition, the microcontroller 17 uses the CLL-based lighting indication control drive circuit 13 to make the light source 3 light up in the CLL lighting mode (illumination mode).

[0081] Therefore, when the light source 3 is turned off, it can gradually turn off from the state of being lit as CLL (with the same brightness).

[0082] In addition, the drive circuit 13 supplies the light source 3 with a drive current Ik corresponding to the current value of the control signal Sb according to the duty cycle of the PWM signal Sa.

[0083] Therefore, by setting the control signal Sb and the PWM signal Sa, the brightness of the light source 3 can be adjusted.

[0084] Additionally, based on the welcome lighting indication, the microcontroller 17 outputs a control signal Sb that changes the current value of the drive current Ik according to the gradual lighting (brightening mode) and gradual dimming (first dimming mode), as well as a PWM signal Sa with a duty cycle of 30%. Furthermore, based on the farewell lighting indication, the microcontroller 17 outputs a control signal Sb that changes the current value of the drive current Ik according to the gradual dimming (second dimming mode), as well as a PWM signal Sa with a duty cycle of 30%.

[0085] Therefore, since the duty cycle of the PWM signal Sa in the gradual fading of the welcome and farewell lights is the same, the same table can be used, which can reduce the development burden.

[0086] Additionally, based on the CLL lighting indication, the microcontroller 17 outputs a control signal Sb that sets the drive current Ik to a predetermined value (0% light reduction) and a PWM signal Sa with a 7% duty cycle (depending on the CLL lighting mode). The period during which the drive current Ik is supplied to the light source 3 with the PWM signal Sa at a 7% duty cycle is shorter than the period during which the drive current Ik is supplied to the light source 3 with a 30% duty cycle.

[0087] This allows the brightness of light source 3 at the start of the farewell lighting to match the brightness of the CLL lighting mode.

[0088] In addition, based on the indication that the DRL is lit, the microcontroller 17 outputs a control signal Sb that sets the drive current Ik to a predetermined value (0% light reduction) and a PWM signal Sa with a 100% duty cycle. The period during which the drive current Ik is supplied to the light source 3 with the PWM signal Sa at a 100% duty cycle is longer than the period during which the drive current Ik is supplied to the light source 3 with a 30% duty cycle.

[0089] Therefore, in DRL lighting mode, light source 3 can be brightly lit.

[0090] In addition, the driving circuit 13 includes: a current output circuit 131, which outputs a driving current Ik corresponding to the control signal Sb; and a dimming switch 132, which is disposed between the current output circuit 131 and the light source 3, and is turned on and off based on the PWM signal Sa.

[0091] Therefore, by setting the control signal Sb and the PWM signal Sa, the current supplied (output) to the light source 3 can be adjusted, and the brightness of the light source 3 can be adjusted.

[0092] In addition, the vehicle lamp 1 of this embodiment includes the lighting circuit 10 and the light source 3 described above.

[0093] This allows for welcoming and farewell lighting, and also reduces the development burden.

[0094] ===Other Embodiments=== The above embodiments are provided for ease of understanding of the present invention and are not intended to limit or explain the present invention. Furthermore, it goes without saying that the present invention can be modified and improved without departing from its spirit, and the present invention includes its equivalents.

[0095] Explanation of reference numerals in the attached diagram: 1: Vehicle lamp; 2: Battery; 3: Light source; 10: Lighting circuit; 11: VCC circuit; 13: Drive circuit; 15: IF circuit; 17: Microcontroller; 100: ECU; 131: Current output circuit; 131a: Switching element; 131b: Switching control circuit; 132: Dimming switch; 171: Storage unit; 172: Processing unit; D1~D4: Light-emitting elements; R1, R2: Resistors; Sa: PWM signal; Sb: Control signal; T1, T2: Meters.

Claims

1. A lighting circuit comprising: a driving circuit that supplies a driving current to a light source; and a control circuit including a storage unit that controls the driving circuit, wherein the storage unit stores first information related to the driving current in a brightness enhancement mode and second information related to the driving current in a first brightness reduction mode, wherein... The brightness enhancement mode gradually reduces the brightness of the light source after it is turned off to a first brightness level. The first brightness reduction mode gradually dims the brightness of the light source from the first brightness level until the light source is turned off. The control circuit controls the drive circuit based on a first instruction, using the first information and the second information, so that the light source is turned on in the brightness enhancement mode and then turned off in the first brightness reduction mode. Based on a second instruction, the control circuit controls the drive circuit using a portion of the second information so that the light source is turned off in a second brightness reduction mode, wherein the second brightness reduction mode gradually dims the brightness of the light source from a second brightness level that is dimmer than the first brightness level until the light source is turned off.

2. The lighting circuit according to claim 1, characterized in that, The control circuit controls the drive circuit based on a third instruction to illuminate the light source in an illumination mode, wherein the illumination mode causes the brightness of the light source to be the second brightness.

3. The lighting circuit according to claim 2, characterized in that, The driving circuit supplies the light source with a driving current corresponding to the current value of the control signal according to the duty cycle of the PWM signal.

4. The lighting circuit according to claim 3, characterized in that, Based on the first indication, the control circuit outputs a control signal that changes the current value of the drive current according to the brightness enhancement mode and the first brightness reduction mode, and a PWM signal with a first duty cycle. Based on the second indication, it outputs a control signal that changes the current value of the drive current according to the second brightness reduction mode, and a PWM signal with the first duty cycle.

5. The lighting circuit according to claim 4, characterized in that, Based on the third indication, the control circuit outputs a control signal that sets the current value of the drive current to a predetermined value according to the lighting mode, and a PWM signal with a second duty cycle different from the first duty cycle, wherein the period for supplying the drive current to the light source under the second duty cycle is shorter than the period for supplying the drive current to the light source under the first duty cycle.

6. The lighting circuit according to claim 5, characterized in that, The control circuit outputs a control signal that makes the drive current value the predetermined value, and a PWM signal with a third duty cycle, based on a fourth indication, wherein the period for which the drive current is supplied to the light source under the third duty cycle is longer than the period for which the drive current is supplied to the light source under the first duty cycle.

7. The lighting circuit according to claim 3, characterized in that, The driving circuit includes: an output circuit that outputs the driving current corresponding to the control signal; and a switch disposed between the output circuit and the light source, which is turned on and off based on the PWM signal.

8. A vehicle lamp comprising: a lighting circuit according to any one of claims 1 to 7; and the light source.

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