Driving device

Abstract

To provide a driving device capable of suppressing heat generation while keeping contact current.SOLUTION: A driving device 1 includes: a driver 20 which lights a lighting device 30 equipped on a vehicle 5 by receiving a command signal S1 or S2; a control part 10 which lights the lighting device 30 by outputting the command signal S1 to the driver 20; a line L1 through which current from a battery B flows through a switch SW opening / closing according to user operation; a line L2 which is electrically connected between the line L1 and the driver 20, and outputs current flowing through the line L1 when the switch SW is closed as the command signal S2 to the driver 20; a dummy load 42 which is provided to assure contact current of the switch SW; and a linear regulator 41 which has an input port 41a electrically connected to the line L1 and an output port 41b connected to the ground through the dummy load 42, and converts voltage inputted to the input port 41a and outputs it from the output port 41b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a drive device. [Background technology]

[0002] The brake lamp illumination control circuit described in Patent Document 1 includes a foot brake switch that is turned on when the foot brake is applied, and a brake lamp that is turned on when a current flows from a power source when the switch is turned on. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 61-101048 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration of Patent Document 1, the contact current of the switch must be equal to or greater than a specified value in order for the switch to operate stably. Here, the power supply voltage fluctuates within a voltage fluctuation range. For this reason, if a resistor is provided so that the contact current of the switch is equal to or greater than a specified value when the power supply voltage is at its maximum value, the contact current of the switch may be less than the specified value when the power supply voltage is at its minimum value, which may cause the switch to operate unstable. On the other hand, if a resistor is provided so that the contact current of the switch is equal to or greater than a specified value when the power supply voltage is at its minimum value, a large current will flow through the resistor when the power supply voltage reaches its maximum value, causing a problem of heat generation.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide a drive device that can suppress heat generation while ensuring contact current. [Means for solving the problem]

[0006] In order to achieve the above object, the drive device according to the present disclosure comprises: A driver that receives the first command signal or the second command signal and turns on a lighting device mounted on a vehicle; a control unit that outputs the first command signal to the driver to turn on the lighting device via the driver; a first line through which current flows from the battery via a switch that opens and closes in response to a user's operation; a second line electrically connected between the first line and the driver, and configured to output a current flowing through the first line as the second command signal to the driver when the switch is closed by a user's operation; a load resistor provided to ensure a contact current of the switch; and a linear regulator having an input port electrically connected to the first line and an output port connected to ground via the load resistor, converting a voltage input to the input port into a constant voltage and outputting the constant voltage from the output port. Effect of the Invention

[0007] According to the present disclosure, heat generation can be suppressed while ensuring contact current. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram of a drive device according to an embodiment of the present disclosure. [Diagram 2] FIG. 4 is a block diagram of a portion of a drive device according to a comparative example. [Diagram 3] 4 is a timing chart showing the operation of a switch, a linear regulator, and a lighting fixture according to an embodiment of the present disclosure, and the states of various signals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A vehicle having a drive device for driving a lighting device according to an embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. 1, a vehicle 5 includes a battery B, a lighting device 30, a switch SW, a drive device 1 that drives the lighting device 30, and an automatic driving system 7.

[0010] The lighting device 30 is a lamp, in this example, a brake lamp, mounted on the vehicle 5. The lighting device 30 is turned on by a current flowing from the output terminal 1b of the drive device 1. The lighting device 30 is made of an LED (Light Emitting Diode).

[0011] The switch SW is opened and closed by operating a foot brake, which is an operating means (not shown) operated by the driver. The switch SW is electrically connected between the battery B and the drive device 1. When the switch SW is closed by operating the operating means, a current from the battery B is input to the input terminal 1a of the drive device 1.

[0012] The automatic driving system 7 is a system that controls the behavior of the vehicle 5. The automatic driving system 7 outputs automatic driving information If1 indicating the content of automatic driving to an automatic driving information input terminal 10f (described later) of the drive device 1. The automatic driving system 7 is not limited to a fully automatic driving system, and may be a system that assists the driver in driving, for example, an automatic collision avoidance braking system.

[0013] The driving device 1 operates by receiving power from the battery B, and controls the lighting of the lighting device 30 according to the opening and closing of the switch SW and / or the contents of the automatic driving information If1. The supply voltage of the battery B varies within a range of 9V to 16V. The driving device 1 includes a control unit 10, a driver 20, diodes D1 to D3, lines L1 to L3, a linear regulator 41, a dummy load 42, an input terminal 1a, and an output terminal 1b.

[0014] The control unit 10 is a microcomputer, and drives the lighting device 30 to light via the driver 20, and switches the linear regulator 41 between an on state and an off state. The control unit 10 is operated by an ignition power supply (not shown) of the vehicle 5. The control unit 10 includes a regulator control terminal 10a, a switch detection terminal 10b, a lighting control terminal 10c, a current detection terminal 10d, a supply current detection terminal 10e, and an automatic driving information input terminal 10f.

[0015] The regulator control terminal 10a is electrically connected to the enable terminal 41c of the linear regulator 41, and outputs an operation command signal Sa to the enable terminal 41c.

[0016] The switch detection terminal 10b is electrically connected to the input terminal 1a via the line L1. The switch detection terminal 10b receives a switch detection signal Sb indicating the open / closed state of the switch SW.

[0017] The lighting control terminal 10c is electrically connected to the input terminal 20a of the driver 20 via the line L2. The lighting control terminal 10c outputs a command signal S1 to the input terminal 20a of the driver 20. The backflow prevention diode D2 is provided on the line L2 such that its cathode terminal faces the intersection of the lines L2 and L3.

[0018] The line L3 is connected between the line L1 and the input terminal 20a of the driver 20, and outputs the switch detection signal Sb flowing through the line L1 to the input terminal 20a of the driver 20 as a command signal S2 to the driver 20. The reverse current prevention diode D3 is provided on the line L3 with its cathode terminal facing the intersection of the lines L2 and L3.

[0019] The current detection terminal 10d is electrically connected to the detection terminal 20c of the driver 20. The current detection terminal 10d receives a detection signal Sd indicating the current flowing through the driver 20.

[0020] The supply current detection terminal 10e is electrically connected to the output terminal 20b of the driver 20. The supply current detection terminal 10e receives a detection signal Se indicating the voltage output from the driver 20.

[0021] The control unit 10 recognizes the open / closed state of the switch SW by inputting the switch detection signal Sb via the switch detection terminal 10b. In this example, when the switch SW is in the closed state, the switch detection signal Sb is on, and when the switch SW is in the open state, the switch detection signal Sb is off.

[0022] In addition, the control unit 10 turns on the linear regulator 41 by outputting an operation command signal Sa (more precisely, turning on the operation command signal Sa) via the regulator control terminal 10a, and turns off the linear regulator 41 by stopping the output of the operation command signal Sa (more precisely, turning off the operation command signal Sa). The operation of the linear regulator 41 will be described later.

[0023] In addition, the control unit 10 receives automatic driving information If1 via the automatic driving information input terminal 10f, and recognizes the deceleration of the vehicle 5 from the received automatic driving information If1. When the control unit 10 determines that the deceleration of the vehicle 5 is equal to or greater than a certain deceleration, it outputs a command signal S1 (more precisely, turns on the command signal S1) via the lighting control terminal 10c to turn on the lighting device 30 via the driver 20. This certain deceleration is set to a deceleration that requires the brake lamps to be turned on. When the control unit 10 determines that the deceleration of the vehicle 5 is less than a certain deceleration, it stops outputting the command signal S1 (to be precise, turns off the command signal S1) to turn off the lighting device 30 via the driver 20.

[0024] Furthermore, the control unit 10 receives a detection signal Sd via a current detection terminal 10d, and recognizes the current flowing through the driver 20 based on the received detection signal Sd. Furthermore, the control unit 10 receives a detection signal Se via the supply current detection terminal 10e, and recognizes the voltage output from the driver 20 to the lighting device 30 based on the received detection signal Se.

[0025] The driver 20 is a high-side switch IC (Integrated Circuit) electrically connected to the control unit 10 and between the input terminal 1a and the output terminal 1b. The driver 20 includes an input terminal 20a, an output terminal 20b, and a detection terminal 20c. The input terminal 20a is electrically connected to the lines L2 and L3, and receives the command signal S1 or S2. The output terminal 20b of the driver 20 is electrically connected to the lighting device 30 via the output terminal 1b of the driving device 1. When at least one of command signals S1 and S2 (more precisely, at least one of command signals S1 and S2 is turned on) is input via input terminal 20a, driver 20 outputs a current via output terminal 20b to light lighting device 30. Driver 20 is electrically connected to a power supply device (such as an on-board battery) (not shown), and outputs a current based on the power supplied by the power supply device.

[0026] The driving device 1 can turn on the lighting device 30 either manually (by operating the foot brake) or by the automatic driving system 7. A method for manually turning on or off the lighting device 30 will be described below. When the foot brake (not shown) is operated, the switch SW switches from an open state to a closed state, and current from the battery B is output to the driver 20 as a command signal S2 via the input terminal 1a → line L1 → L3. As a result, the driver 20 starts outputting current to the lighting device 30, turning on the lighting device 30. When the foot brake is released, the switch SW switches from a closed state to an open state, and the output of the command signal S2 is stopped. As a result, the output of current from the driver 20 is stopped, and the lighting device 30 is turned off. This turning on and off of the lighting device 30 depending on whether or not the foot brake is operated is possible regardless of the state of the vehicle 5 (on / off of the ignition power) because the control unit 10 is not involved.

[0027] Next, a method for turning on or off the lighting device 30 using the automatic driving system 7 will be described. When the vehicle 5 is traveling automatically by the automatic driving system 7, if the control unit 10 determines based on the input automatic driving information If1 that the vehicle 5 has decelerated at a deceleration rate equal to or greater than a certain deceleration rate, the control unit 10 outputs a command signal S1 to the driver 20. As a result, the driver 20 starts outputting a current to the lighting device 30, and turns on the lighting device 30. Also, if the control unit 10 determines based on the input automatic driving information If1 that the vehicle 5 has decelerated at a rate less than the certain deceleration rate, the control unit 10 stops outputting the command signal S1. As a result, the output of the current from the driver 20 is stopped, and the lighting device 30 is turned off.

[0028] The linear regulator 41 and the dummy load 42 are contact current securing means for securing the contact current of the switch SW. Specifically, the diode D1, the linear regulator 41, and the dummy load 42 are connected in series with each other between the line L1 and the ground. The diode D1 is closest to the line L1, the dummy load 42 is closest to the ground, and the linear regulator 41 is provided between the diode D1 and the dummy load 42.

[0029] The reverse current prevention diode D1 is provided so that its cathode terminal faces the linear regulator 41.

[0030] The dummy load 42 is electrically connected between the linear regulator 41 and the ground. The dummy load 42 is a resistive load for making the contact current of the switch SW equal to or greater than a preset required contact current. This required contact current is a value required for stable operation of the switch SW. In this example, the required contact current is 0.5 A. The resistance value of the dummy load 42 is set so that, upon receiving the output voltage of the linear regulator 41, a current equal to or greater than the required contact current (for example, 0.5 A) flows.

[0031] The linear regulator 41 includes an input port 41a for inputting an input voltage, an output port 41b for outputting an output voltage, and an enable terminal 41c for inputting a command signal Sa for commanding the on / off of the linear regulator 41. The linear regulator 41 generates an output voltage by dropping an input voltage. The input port 41a is electrically connected to a line L1 via a diode D1. The output port 41b is connected to ground via a dummy load 42. The linear regulator 41 outputs a constant output voltage regardless of fluctuations in the input voltage. The linear regulator 41 is an LDO (Low Drop Out) regulator. The linear regulator 41 consumes the same current as the downstream dummy load 42. This makes it possible to suppress power consumption and heat generation in the drive device 1 while maintaining the contact current of the switch SW at or above the required contact current (e.g., 0.5 A) even if the supply voltage of the battery B fluctuates. This point will be specifically described below in comparison with a comparative example.

[0032] In the comparative example of FIG. 2, only the dummy load 142 is connected between the line L1 and ground. In this comparative example, even when the supply voltage of the battery B is the minimum value of 9V, it is necessary to ensure 0.5A as the required contact current of the switch SW. Therefore, when the supply voltage of the battery B is the maximum value of 16V, power consumption of 16V×0.5A×(16V / 9V)≒14.2W occurs, and the dummy load 142 becomes a heat source. It is difficult to deal with this heat generation by the board design alone, and additional heat dissipation measures such as adding a heat sink are required.

[0033] On the other hand, in the present embodiment shown in FIG. 1, even if the supply voltage of the battery B fluctuates, the output voltage of the linear regulator 41 is constant (for example, 5V), so that the contact current of the switch SW can be maintained at or above the required contact current. For example, when the supply voltage of the battery B is a maximum value of 16V, the voltage drop in the diode D1 is 0.7V, the voltage drop in the linear regulator 41 is 10.3V, the voltage drop in the dummy load 42 is 5.0V, and a current of 0.5A flows through the diode D1, the linear regulator 41, and the dummy load 42. Therefore, the power consumption in the diode D1 is 0.7V×0.5A=0.35W, the power consumption in the linear regulator 41 is 10.3V×0.5A=5.15W, and the power consumption in the dummy load 42 is 5.0V×0.5A=0.25W. Therefore, the total power consumption is 8W, and the power consumption can be suppressed compared to the above comparative example. Furthermore, in this embodiment, by suppressing power consumption and heat generation, the need for heat dissipation measures such as adding a heat sink is also reduced.

[0034] Moreover, the linear regulator 41 switches between an on state and an off state based on a command signal Sa from the control unit 10. When the linear regulator 41 is on, it is capable of stepping down the input voltage and outputting an output voltage. When the linear regulator 41 is off, it is unable to output an output voltage and is in an open state where it is electrically disconnected. In other words, when the linear regulator 41 is off, no current flows from the switch SW to the dummy load 42.

[0035] 3, the operation of the switch SW, the linear regulator 41, and the lighting device 30 when the switch SW is closed by operating the operating means to turn on the lighting device 30 will be described. At the start of this timing chart, the switch SW is in an open state, the output of current from the driver 20 is stopped, and the lighting device 30 is in an off state, but the linear regulator 41 is turned on in response to a command signal Sa from the control unit 10 (more precisely, the command signal Sa is turned on).

[0036] The control unit 10 maintains the command signal Sa ON and the linear regulator 41 ON for a certain time T1 from the time t1 when the command signal S2 is switched from OFF to ON, that is, when the switch SW is switched from an open state to a closed state. The certain time T1 is set to a time (for example, 1 millisecond or more) that allows the contact current of the switch SW (switch detection signal Sb) to remove the oxide film generated on the contact of the switch SW, or a relatively short time (about several tens of milliseconds including the delay when taking in the line L1, the operation clock period of the control unit 10, and the time required for program execution, etc.) that the control unit 10 can execute. Since the linear regulator 41 is ON within the certain time T1, it is possible to ensure the contact current of the switch SW. In addition, when the switch SW is closed, the command signal S2 flowing from the battery B through the switch SW is applied to the input terminal 20a of the driver 20, so that the driver 20 is turned ON, and the driver 20 supplies a current to the lighting device 30, and the lighting device 30 is turned on.

[0037] The control unit 10 stops output of the command signal Sa (more precisely, turns off the command signal Sa) at time t2 after a certain period of time T1 has elapsed, thereby turning off the linear regulator 41. This prevents current more than necessary from flowing through the dummy load 42, making it possible to suppress power consumption and heat generation in the diode D1, the linear regulator 41, and the dummy load 42. If the contact current of the switch SW can be secured at the moment the switch SW is closed, stable operation of the switch SW can be achieved, so there is no problem if the contact current flows for a short period of time, for example in pulses.

[0038] The control unit 10 turns on the linear regulator 41 again after the switch SW is switched from on to off, i.e., after the switch SW is switched from a closed state to an open state. This allows the linear regulator 41 to be in an on state when the lighting device 30 is turned on again.

[0039] Even if the linear regulator 41 is turned off, the command signal S2 remains applied to the input terminal 20a of the driver 20, and therefore the lighting device 30 remains lit as long as the switch SW is closed.

[0040] (effect) According to the embodiment described above, the following effects are achieved. (1) The drive device 1 includes a driver 20 that receives a command signal S1, which is an example of a first command signal, or a command signal S2, which is an example of a second command signal, to turn on a lighting device 30 mounted on a vehicle 5; a control unit 10 that outputs the command signal S1 to the driver 20, thereby turning on the lighting device 30 via the driver 20; a line L1, which is an example of a first line through which a current from a battery B flows via a switch SW that opens and closes in response to a user's operation; a line L2, which is an example of a second line that is electrically connected between the line L1 and the driver 20 and outputs to the driver 20 as a command signal S2 the current that flows through the line L1 when the switch SW is closed by the user's operation; a dummy load 42, which is an example of a load resistor provided to ensure a contact current of the switch SW; and a linear regulator 41 that has an input port 41a electrically connected to the line L1 and an output port 41b connected to ground via the dummy load 42, and converts the voltage input to the input port 41a into a constant voltage and outputs it from the output port 41b. According to this configuration, even if the supply voltage of battery B fluctuates, the output voltage of linear regulator 41 remains constant, so the required contact current of switch SW can be maintained. Therefore, even if the supply voltage of battery B is low, the contact current of switch SW can be ensured, and even if the supply voltage of battery B is high, a large current does not flow through dummy load 42, so heat generation can be suppressed. In addition, power consumption of drive device 1 can also be suppressed.

[0041] (2) The linear regulator 41 has an enable terminal 41c that receives a command signal Sa, which is an example of a third command signal from the control unit 10. The control unit 10 can switch the linear regulator 41 between an ON state in which the linear regulator 41 can output a voltage to the dummy load 42 and an OFF state in which the linear regulator 41 cannot output a voltage to the dummy load 42, via the command signal Sa, and keeps the linear regulator 41 in the ON state for a preset fixed time T1 after the switch SW is switched from the open state to the closed state, and keeps the linear regulator 41 in the OFF state after the fixed time T1 has elapsed. According to this configuration, after the lapse of the fixed time T1, no current flows through the dummy load 42, so that heat generation in the dummy load 42 can be suppressed.

[0042] (3) When the control unit 10 receives automatic driving information If1 indicating that the vehicle 5 has automatically decelerated at or above a certain deceleration, the control unit 10 outputs a command signal S1 to the driver 20 to turn on the brake lamps, which are the lighting devices 30. In recent years, lighting devices such as brake lights need to be automatically turned on not only in response to the operation of an operating means such as a foot brake, but also in response to automatic braking in an automatic driving system including driving assistance. For this reason, in addition to a power supply system that turns on the brake lights by operating the operating means, a power supply system that automatically turns on the brake lights without operating the operating means is required. With the above configuration, it is possible to suppress heat generation of the dummy load 42 while ensuring the contact current of the switch SW and enabling the lighting device 30 to be turned on by two power systems.

[0043] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) can be made as appropriate within the scope of the present disclosure. An example of a modification will be described below.

[0044] (Modification) In the above embodiment, the lighting device 30 was a brake lamp, but this is not limited to this and may be, for example, a hazard lamp or a turn signal as long as it is a lamp mounted on the vehicle 5, and in particular a lamp that is turned on by either the autonomous driving system 7 or a user operation.

[0045] In the above embodiment, the control unit 10 can control the linear regulator 41 to switch between the on state and the off state through the command signal Sa, but this switching control may not be possible. In this case, the linear regulator 41 may be always on.

[0046] In the above embodiment, the drive device 1 may include a temperature detection unit, such as a thermistor, that measures temperature near the dummy load 42. The control unit 10 may keep the linear regulator 41 off by setting the fixed time T1 to 0 milliseconds when the temperature detected by the temperature detection unit becomes equal to or higher than a threshold value, or may set the fixed time T1 to be shorter as the detected temperature increases. Furthermore, the control unit 10 may intermittently switch the linear regulator 41 between on and off. In this case, the ratio of the off time to the on time may be increased as the detected temperature increases. As a result, the driving device 1 is prevented from becoming too hot. [Explanation of symbols]

[0047] 1 Drive unit 1a Input terminal 1b Output terminal 5. Vehicles 7. Autonomous Driving Systems 10 Control section 10a Regulator control terminal 10b Switch detection terminal 10c Lighting control terminal 10d Current detection terminal 10e Supply current detection terminal 10f Automatic driving information input terminal 20 Drivers 20a Input terminal 20b Output terminal 20c Detection terminal 30 Lighting equipment 41 Linear regulator 41a Input port 41b Output port 41c Enable terminal 42,142 Dummy load B Battery D1~D3 Diodes L1~L3 lines S1,S2 command signal Sa operation command signal Sb Switch detection signal Sd,Se detection signal T1 fixed time t1,t2 time SW Switch If1 Autonomous Driving Information

Claims

1. a driver that receives the first command signal or the second command signal and turns on a lighting device mounted in the vehicle; a control unit that outputs the first command signal to the driver to turn on the lighting device via the driver; a first line through which current flows from the battery via a switch that opens and closes in response to a user's operation; a second line electrically connected between the first line and the driver, and configured to output, to the driver, a current flowing through the first line as the second command signal when the switch is closed by a user's operation; a load resistor provided to ensure a contact current of the switch; a linear regulator having an input port electrically connected to the first line and an output port connected to ground via the load resistor, the linear regulator converting a voltage input to the input port into a constant voltage and outputting the constant voltage from the output port; Drive unit.

2. the linear regulator includes an enable terminal to which a third command signal from the control unit is input, the control unit is capable of switching the linear regulator between an ON state in which a voltage can be output to the load resistance and an OFF state in which a voltage cannot be output to the load resistance through the third command signal, and keeps the linear regulator in the ON state for a preset fixed time period after the switch is switched from an open state to a closed state, and keeps the linear regulator in the OFF state after the fixed time period has elapsed. The drive device according to claim 1 .

3. When the control unit receives automatic driving information indicating that the vehicle has automatically decelerated by a certain deceleration or more, the control unit outputs the first command signal to the driver to turn on the brake lamp, which is the lighting device.

3. A drive device according to claim 1 or 2.

Images