Heater control device, heater control method, and vehicle lamp

Abstract

To prevent a heater provided in a vehicle lamp from adversely affecting a LiDAR sensor built in the lamp.SOLUTION: A heater control device disclosed herein is provided in a vehicle lamp and is configured to detect a rising edge of an emission period of sensor light emitted from an object detection LiDAR sensor built in the vehicle lamp, and start supplying a drive voltage to a heater upon detection of the rising edge.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a heater control device, a heater control method, and a vehicle lamp.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2020-30908 (Patent Document 1) discloses a heater provided at the rear of a vehicle, a temperature sensor that measures the outside air temperature, and a control unit that controls energization of the heater according to the measured value of the temperature sensor. When the measured value of the outside air temperature is equal to or higher than the first temperature and lower than the second temperature, the heater is energized, and when the measured value is lower than the first temperature or equal to or higher than the second temperature, energization of the heater is stopped. The heater is provided, for example, in the taillight of a vehicle.

[0003] By the way, in recent years, in order to configure, for example, a driving assistance system or an autonomous driving system, it has become common to mount an object detection sensor using a technology such as LiDAR (Light Detection And Ranging) on a vehicle. Here, consider a case where an object detection sensor as described above is incorporated in a vehicle lamp. In this case, when the heater is energized, the energy at the time of current rise is electromagnetically radiated and enters the drive circuit of the object detection sensor as noise, which may have an adverse effect (for example, a decrease in detection accuracy).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A specific aspect of the present disclosure aims to provide a technique capable of avoiding an adverse effect on a sensor caused by a heater.

Means for Solving the Problems

[0006] [1] A vehicle lamp according to one aspect of the present disclosure includes a housing, an outer lens disposed on the front surface of the housing, A lamp unit that is disposed within the housing and irradiates light to the outside through the outer lens; Se a light emitting unit that emits sensor light, and an object detection sensor having a light receiving unit that receives reflected light reflected from a detection object, Pre a heater disposed in a range corresponding to the emission range of the sensor light, a heater driving device having a light emission timing detection unit and a drive voltage output unit, and connected to the heater, and includes The object detection sensor includes a control circuit that controls the light emitting unit to intermittently and repeatedly emit the sensor light, and controls to provide a reception blank period, which is a period for ignoring the reflected light received by the light receiving unit within a certain period from the emission timing of the sensor light. Pre The light emission timing detection unit detects the rising edge of the light emission period of the sensor light emitted from the light emitting unit of the object detection sensor 、 The drive voltage output unit, and in response to the rising edge Within the reception blank period starts supplying a drive voltage from the drive voltage output unit of the heater driving device to the heater Set the start period , Each time the sensor light is emitted, or intermittently in conjunction with the emission of the sensor light, supply the drive voltage so that the light emission period of the sensor light overlaps with the period for supplying the drive voltage. It is a vehicle lamp. [2] A method for controlling a heater of a vehicle lamp according to one aspect of the present disclosure is Of the above [1] a method for controlling a heater of a vehicle lamp, wherein the light emission timing detection unit of the heater driving device detects the rising edge of the light emission period of the sensor light emitted from the light emitting unit of the object detection sensor First step; the drive voltage output unit sets a start period of the drive voltage to the heater in response to the rising edge of the light emission period of the sensor light detected by the light emission timing detection unit Second step; the drive voltage output unit starts supplying a drive voltage to the heater Third step; and includes Mi The third step is performed within the light emission period of the sensor light emitted from the light emitting unit of the object detection sensor. It is a method for controlling a heater of a vehicle lamp.

[0007] According to the above configuration, it is possible to avoid an adverse effect on the sensor by the heater.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] FIG. 1(A) is a schematic view of the appearance of a vehicle lamp according to an embodiment as seen from the front side. FIG. 1(B) is a view showing the internal structure of this vehicle lamp, for example, a view obtained by cutting FIG. 1(A) in a horizontal plane and looking from above. The vehicle lamp 1 of the present embodiment shown in each figure is, for example, arranged at the front part of a vehicle and used as a headlamp. Here, only one vehicle lamp 1 arranged on either the left or right is shown. The vehicle lamp 1 includes a housing 10, an outer lens 11, a lamp unit 12, an object detection sensor 13, a light sensor 14, an optical filter 15, a heater 16, and a controller 17.

[0010] The housing 10 houses the lamp unit 12, the object detection sensor 13, the light sensor 14, the optical filter 15, the heater 16, and the controller 17 of the vehicle lamp 1, and is made of an appropriate material such as plastic.

[0011] The outer lens 11 is a front cover attached to the housing 10, and protects each of the lamp unit 12 and the like arranged inside the housing 10. This outer lens 11 is made of a member that transmits light.

[0012] The lamp unit 12 is arranged inside the housing 10, and turns on and off under the control of the controller 17. The light from the lamp unit 12 is emitted to the outside through the outer lens 11 and irradiates the front of the vehicle.

[0013] The object detection sensor 13 emits pulsed laser light (sensor light) while scanning a wide range in front of the vehicle, and detects the shape of the object and the relative distance to the object by detecting the reflected light obtained by the reflection of this laser light on the surface of the object. In the present embodiment, a LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging) device is used as the object detection sensor 13. The laser light emitted from the object detection sensor 13 of the present embodiment is, for example, laser light having a near-infrared wavelength of about 750 nm to 1.5 μm.

[0014] The optical sensor 14 is provided at a position where a part of the laser light emitted from the object detection sensor 13, such as the front side of the object detection sensor 13, can enter. The optical sensor 14 detects the incident laser light and outputs a detection signal corresponding to its intensity to the controller 17.

[0015] The optical filter 15 is a band-pass filter that transmits light of a specific wavelength and attenuates light of other wavelengths. As the optical filter 15 in this embodiment, a band-pass filter is used that is set to transmit light corresponding to the wavelength of the laser light of the object detection sensor 13 and attenuate light of other wavelengths, particularly light of far-infrared wavelengths (for example, 3.0 μm to 1 mm) emitted from the heater 16.

[0016] The heater 16 is for generating heat to prevent snow from adhering to the outer lens 11, etc. The heater 16 is, for example, inside the outer lens 11 as shown in the figure, and is arranged at least in a range corresponding to the emission range of the laser light of the object detection sensor 13. As this heater 16, a conductive film with high transparency to at least the laser light emitted from the object detection sensor 13 is used. For example, it is preferable to configure the heater 16 using a ZnO film having conductivity and high light transmittance in a wide band as described in Japanese Patent Application Laid-Open No. 2017-133079.

[0017] The controller 17 controls the lighting and extinguishing of the lamp unit 12 and also controls the operation of the heater 16. The controller 17 is connected to each of the lamp unit 12, the optical sensor 14, and the heater 16. This controller 17 is realized, for example, by using a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and causing the computer to execute a predetermined operation program.

[0018] FIG. 2 is a block diagram for explaining a configuration related to operation control of a vehicle lamp. As shown in the figure, the object detection sensor 13 includes a light emitting unit 31, a light receiving unit 32, and a control circuit 33. Further, the controller 17 includes a heater driving device 40 and a lamp driving device 50. The heater driving device 40 includes a light emission timing detection unit 41 and a drive voltage output unit 42.

[0019] The light emitting unit 31 of the object detection sensor 13 emits laser light while scanning in a two-dimensional direction or a three-dimensional direction. A part of the emitted laser light is detected by the optical sensor 14. The position of the optical sensor 14 is preferably set at a position that does not affect the scanning of the laser light by the light emitting unit 31. The emitted laser light passes through the optical filter 15 and the heater 16 and is emitted to the outside, and is reflected by the object 2.

[0020] The light receiving unit 32 of the object detection sensor 13 receives the reflected light from the object 2 and outputs a detection signal corresponding to its magnitude. The control circuit 33 controls the operation of the light emitting unit 31 and generates a distance image including the mutual distance between the object 2 and the shape of the object 2 based on the intensity and timing of the reflected light received by the light receiving unit 32. The data of the generated distance image is supplied to a higher-level device (not shown).

[0021] The heater driving device 40 controls the operation of the heater 16. The lamp driving device 50 controls the lighting and extinguishing of the lamp unit 12.

[0022] The light emission timing detection unit 41 of the heater driving device 40 detects the rising edge (light emission timing) of the light emission period of the laser light emitted from the object detection sensor 13 based on the detection signal of the optical sensor 14. The drive voltage output unit 42 starts supplying the drive voltage to the heater in response to the rising edge of the laser light detected by the light emission timing detection unit 41.

[0023] FIG. 3(A) is a diagram showing an example of the drive voltage waveform of the heater. FIG. 3(B) is a diagram showing an example of the light intensity waveform of the laser light emitted from the object detection sensor 13. FIG. 3(C) is a diagram showing an example of the light intensity waveform of the light received by the object detection sensor 13.

[0024] As shown in FIG. 3(B), the laser light emitted from the object detection sensor 13 is intermittently emitted repeatedly at a constant period. The pulse width W and the repetition period T of this laser light are appropriately set according to the distance resolution, the maximum detection distance, etc. For example, if the distance resolution is 75 cm, the pulse width W is set to 5 ns, and if the maximum detection distance is 200 m, the repetition period T including the internal processing time etc. is set to 40 ms (corresponding to 25 Hz). Also, as shown in FIG. 3(C), in order to prevent false detection when detecting the reflected light, a reception blank period B is provided, which is a period for ignoring the reflected light within a certain period from the emission timing of the laser light. This reception blank period B is set to a period of 10 ns starting from the emission timing of the laser light, for example.

[0025] For such an operation of the object detection sensor 13, the light emission timing detection unit 41 of the heater drive device 40 detects the rising edge of the laser light using the detection signal output from the optical sensor 14. In response to this detected rising edge, as shown in FIG. 3(A), the supply of the drive voltage to the heater 16 is started by the drive voltage output unit 42. As shown in the figure, the drive voltage is repeatedly supplied every time the laser light is emitted. By increasing or decreasing the number of repetitions, or supplying it intermittently, the temperature of the heater 16 can be controlled.

[0026] Thus, even if noise (the waveform shown in a spike shape in FIG. 3(C)) due to electromagnetic radiation of energy accompanies the start of the supply of the drive voltage to the heater 16 and jumps into the receiving unit 32 of the object detection sensor 13, since it is within the above-described reception blank period, it can be removed as noise. Therefore, even when the light intensity of the reflected light is small, it is possible to detect the object 2.

[0027] Note that "in response to the rising edge" means that after the rising edge of the laser beam is detected, the supply of the drive voltage starts after an extremely short delay time. Generally speaking, it can be said that it is synchronized with the rising edge, but in principle, it does not mean that the rising edge and the start timing of the supply of the drive voltage exactly coincide.

[0028] Also, as shown in Fig. 3(A), after starting the supply of the drive voltage, the drive voltage output unit 42 stops the supply of the drive voltage at an appropriate time before the reception blank period B elapses. In the illustrated example, the supply of the drive voltage is stopped at almost the same time as the end of the reception blank period B.

[0029] Fig. 4(A) is a diagram showing an example of the drive voltage waveform of the heater of the comparative example. Fig. 4(B) is a diagram showing an example of the light intensity waveform of the laser beam emitted from the object detection sensor 13 of the comparative example. Fig. 4(C) is a diagram showing an example of the light intensity waveform of the light received by the object detection sensor 13 of the comparative example. The comparative example here is an operation example when the drive voltage of the heater 16 is not associated with the light emission timing of the laser beam emitted from the object detection sensor 13.

[0030] As shown in Figs. 4(A) and 4(B), assume that the drive voltage of the heater is intermittently supplied without being linked to the light emission timing of the laser beam from the object detection sensor 13. In this case, as shown in Fig. 4(C), in order to remove the noise (spike-shaped waveform) due to the drive voltage of the heater, for example, if a threshold level th set corresponding to the noise is set, the reflected light received at a light intensity below that will also be excluded. For this reason, for example, there may be a case where the object 2 existing in the distance cannot be detected.

[0031] Fig. 5 is a flowchart showing the flow of the operation by the heater driving device of the controller. Note that the heater control by this heater driving device is executed, for example, when the ambient temperature (the temperature around the vehicle lamp) detected by a temperature sensor (not shown) or the like becomes equal to or lower than a predetermined reference value.

[0032] When the light emission timing detection unit 41 of the heater driving device 40 detects the rising edge (light emission timing) of the light emission period of the laser light emitted from the object detection sensor 13 based on the detection signal of the optical sensor 14 (step S11).

[0033] Next, the drive voltage output unit 42 of the heater driving device 40 sets the start period of the drive voltage to the heater corresponding to the rising edge of the laser light detected by the light emission timing detection unit 41 (step S12), and starts supplying the drive voltage (step S12). Although the time until the end period of the drive voltage is predetermined, it may be appropriately set in the drive voltage output unit.

[0034] Thereafter, it returns to step S11. As a result, the drive voltage is intermittently applied to the heater 16 at a period corresponding to the repetition period of the laser light.

[0035] FIG. 6(A) is a diagram showing an example of the drive voltage waveform of the heater in the modified embodiment. FIG. 6(B) is a diagram showing an example of the light intensity waveform of the laser light emitted from the object detection sensor 13 in the modified embodiment. FIG. 6(C) is a diagram showing an example of the light intensity waveform of the light received by the object detection sensor 13 in the modified embodiment. As shown in FIGS. 6(A) and 6(B), after the supply of the drive voltage to the heater is started corresponding to the rising edge of the laser light in the first period, the supply may be stopped corresponding to the rising edge of the laser light in the second period that comes after the first period. In this case, in the illustrated example, the emission timing of the second laser light is defined as the second period, but it is not limited thereto, and the emission timing of the third and subsequent laser lights may be defined as the second period. For example, the supply of the drive voltage may be started corresponding to the rising edge of the first laser light, the supply of the drive voltage may be continued without being linked to the second laser light, and the supply of the drive voltage may be stopped corresponding to the rise of the third laser light. Since noise due to the drive voltage of the heater is generated largely at the rising time (start period) of the drive voltage, the influence of noise can also be avoided by setting the start period and stop period of the supply of the drive voltage in conjunction with the rising edge of the laser light as described above (see FIG. 6(C)).

[0036] According to the embodiment as described above, it is possible to avoid the adverse effect on the sensor by the heater.

[0037] Note that the present disclosure is not limited to the content of the above-described embodiment, and various modifications can be made and implemented within the scope of the gist of the present disclosure. For example, in the above-described embodiment, the rising edge of the laser light is detected using the optical sensor 14. However, when a signal indicating the rising edge can be directly obtained from the object detection sensor 13, the detection operation of the rising edge in the light emission timing detection unit 41 of the controller 17 may be performed using the signal.

[0038] Also, in the above-described embodiment, the controller 17 in which the heater driving device 40 and the lamp driving device 50 are integrated is exemplified. However, the heater driving device 40 and the lamp driving device 50 may be configured separately.

[0039] Also, in the above-described embodiment, a headlamp is shown as an example of a vehicle lamp, but the vehicle lamp is not limited thereto, and for example, a tail lamp or the like may be used.

Explanation of Reference Numerals

[0040] 1: Vehicle lamp, 10: Housing, 11: Outer lens, 12: Lamp unit, 13: Object detection sensor, 14: Optical sensor, 15: Optical filter, 16: Heater, 17: Controller, 31: Light emitting unit, 32: Light receiving unit, 33: Control circuit, 40: Heater driving device, 41: Light emission timing detection unit, 42: Drive voltage output unit, 50: Lamp driving device

Claims

1. A housing, an outer lens disposed on the front surface of the housing, a lamp unit disposed within the housing and irradiating light to the outside through the outer lens, an object detection sensor having a light emitting portion that emits sensor light and a light receiving portion that receives reflected light reflected from a detection target, a heater disposed in a range corresponding to the emission range of the sensor light, a heater driving device having a light emission timing detection portion and a drive voltage output portion and connected to the heater, comprising, the object detection sensor includes a control circuit that controls the light emitting portion to intermittently and repeatedly emit the sensor light, and controls to provide a reception blank period, which is a period for ignoring the reflected light received by the light receiving portion within a certain period from the emission timing of the sensor light, the light emission timing detection portion detects a rising edge of the light emission period of the sensor light emitted from the light emitting portion of the object detection sensor, the drive voltage output portion sets a start period for starting the supply of the drive voltage from the drive voltage output portion of the heater driving device to the heater within the reception blank period corresponding to the rising edge, and supplies the drive voltage so that the light emission period of the sensor light and the period for supplying the drive voltage overlap each time the sensor light is emitted or intermittently in conjunction with the emission of the sensor light, a vehicle lamp.

2. further comprising a photosensor connected to the light emission timing detection portion and detecting the intensity of the sensor light, detecting the rising edge based on the detection signal of the photosensor, the vehicle lamp according to Claim 1.

3. the supply of the drive voltage is stopped between after the emission of the sensor light and before the reception blank period elapses, the vehicle lamp according to Claim 1 or 2.

4. the supply of the drive voltage is started corresponding to the rising edge of the first period and stopped corresponding to the rising edge of the second period that comes after the first period, the vehicle lamp according to Claim 1 or 2.

5. the heater is a ZnO film provided within the front cover of the vehicle lamp, the vehicle lamp according to any one of Claims 1 to 4.

6. further comprising an optical filter disposed between the heater and the light receiving portion and set to transmit the sensor light and attenuate the light emitted from the heater, the vehicle lamp according to any one of Claims 1 to 5.

7. A method for controlling a heater of a vehicle lamp according to any one of Claims 1 to 6, comprising: a first step in which the light emission timing detection unit of the heater driving device detects a rising edge of a light emission period of the sensor light emitted from the light emitting unit of the object detection sensor; a second step in which the drive voltage output unit sets a start period of a drive voltage to the heater corresponding to the rising edge of the light emission period of the sensor light detected by the light emission timing detection unit; a third step in which the drive voltage output unit starts supplying a drive voltage to the heater; and the third step is performed within a light emission period of the sensor light emitted from the light emitting unit of the object detection sensor. A method for controlling a heater of a vehicle lamp.

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