JP7765373B2 - Anti-fog system - Google Patents

Description

The present invention relates to an anti-fogging system for suppressing fogging of vehicle windows.

Conventionally, vehicles equipped with an imaging device that captures images of the exterior of the vehicle through the vehicle window from the interior of the vehicle are known. Such vehicles are sometimes equipped with an anti-fogging system to prevent fogging on the windows from interfering with imaging by the imaging device. This anti-fogging system includes an anti-fogging device (e.g., a heating device that heats the windows) that prevents fogging on the windows, and a control device that controls the anti-fogging device.

For example, Patent Document 1 discloses a vehicle equipped with a monitoring device capable of monitoring the vehicle's surrounding environment through a translucent window member, a heating device for heating a portion of the window member within the monitoring area of the monitoring device, an air conditioning device for conditioning the interior of the vehicle, and a control device for controlling the operation of the heating device.

The heating device includes a first heating unit and a second heating unit located downstream of the first heating unit in the direction of conditioned air from the air conditioning unit. When the air conditioning unit is operating, the control unit drives the second heating unit with priority over the first and second heating units.

Japanese Patent Application Laid-Open No. 2020-152324

Such anti-fog systems control the heater to prevent fogging on the inside of the vehicle's windows. However, if the outside of the window freezes over, it becomes difficult to capture images using a camera (photography device).

The inventors of the present application therefore came up with the idea of using a heater built into the defogging system to remove ice that has accumulated on the exterior surface of the window. However, when using a heater built into the defogging system, there is a risk that the heater will not generate enough heat or that the heater will generate too much heat, which could put stress on the components that make up the window.

In light of the above background, the present invention aims to provide an anti-fogging system that uses a heater to prevent window fogging, by accelerating window thawing using the heater and appropriately controlling the heater's output. By suppressing window fogging, situations in which vehicle driving control based on the image capture results from the imaging device can be reduced, further improving traffic safety and contributing to the development of sustainable transportation systems.

In order to solve the above problem, one aspect of the present invention is an anti-fogging system (X) for a camera (10) that captures images of the outside of a vehicle (1) through a predetermined viewing area (R) set on a window (6), the system comprising: a heater (31) that heats the viewing area; an outside temperature sensor (40) that detects the temperature outside the vehicle interior (3) as the outside temperature; and a control device (26) that controls the heater based on the outside temperature acquired by the outside temperature sensor. The control device determines whether predetermined de-icing conditions are met based on the outside temperature detected by the outside temperature sensor, and reduces the output of the heater when the de-icing conditions are not met compared to when the conditions are met.

According to this aspect, the heater output is limited when the de-icing conditions are not met. This means that the heater output is not limited when the de-icing conditions are met, which promotes de-icing of the window by the heater. It also prevents excessive heater output when the de-icing conditions are not met. This allows for appropriate control of the heater output.

In the above aspect, preferably, the system further includes a camera internal temperature sensor (41) that detects the internal temperature of the camera as the camera internal temperature, and the control device sets a threshold value (Th) based on the outside-vehicle temperature detected by the outside-vehicle temperature sensor, and determines that the thawing condition is met when the camera internal temperature detected by the camera internal temperature sensor is low.

This aspect allows for appropriate setting of melting conditions to limit heater output.

In the above aspect, preferably, the threshold value is set to be maintained or increased as the outside temperature decreases.

This aspect allows the threshold to be set appropriately.

In the above aspect, preferably, the vehicle further includes an interior temperature sensor (42) that acquires the temperature inside the vehicle compartment as the interior temperature, and the control device sets a threshold value (Th) based on the exterior temperature detected by the exterior temperature sensor, and determines that the de-icing condition is met when the interior temperature acquired by the interior temperature sensor is lower than the threshold value.

This aspect allows for appropriate setting of melting conditions to limit heater output.

In the above aspect, preferably, the threshold value is set to be maintained or decreased as the outside temperature decreases.

This aspect allows the threshold to be set appropriately.

In the above aspect, preferably, the control device is capable of applying a voltage pulse that repeatedly turns on and off to the heater, and changes the output of the heater by changing the duty ratio of the voltage pulse.

This aspect allows for appropriate control of heater output using a simple method.

According to the above aspect, in an anti-fogging system that suppresses fogging of windows by heating with a heater, it is possible to promote de-icing of the windows by the heater and appropriately control the heater output.

FIG. 1 is a perspective view showing a vehicle according to an embodiment of the present invention; FIG. 1 is a perspective view showing a front camera and its peripheral portion according to an embodiment of the present invention; FIG. 1 is a functional block diagram illustrating an anti-fogging system according to an embodiment of the present invention. Control device block diagram Authenticity table according to the first embodiment Output control process flow chart Authenticity table according to the second embodiment Graph showing modified examples of determination information

<Vehicles>
First, a vehicle 1 equipped with an anti-fogging system X according to an embodiment of the present invention will be described with reference to the drawings. An arrow Fr in Figs. 1 and 2 indicates the front of the vehicle 1.

<<First Embodiment>>
1, the vehicle 1 is a four-wheeled vehicle, i.e., an automobile. The vehicle 1 may be an electric vehicle using only an electric motor as a drive source, or may be a hybrid vehicle equipped with an electric motor and an engine as drive sources.

Vehicle 1 has a vehicle body 2 that forms its exterior. The vehicle body 2 is elongated in the fore-and-aft direction of the vehicle. An interior space SP1 is formed inside the vehicle body 2, and a passenger compartment 3 for accommodating occupants is provided in the center of the interior space SP1 in the fore-and-aft direction. The passenger compartment 3 is provided with, for example, multiple front seats 4 (driver's seat, passenger seat) and multiple rear seats 5 arranged behind the front seats 4. In this embodiment, there are two rows of seats, one fore-and-aft, but in other embodiments there may be only one row of seats, or three or more rows of seats, one fore-and-aft.

A front windshield 6 (an example of a window) is provided in the front part of the vehicle body 2, in front of the front seats 4. The front windshield 6 is composed of a panel (window member) made of glass. Note that in other embodiments, the front windshield 6 may be made of a transparent material other than glass (for example, a transparent resin). A rear window 7 is provided in the rear part of the vehicle body 2, behind the rear seats 5. Multiple side doors 8 are provided on both sides of the vehicle body 2, beside the front seats 4 and rear seats 5, and a side window 9 is provided above each side door 8.

As shown in Figures 1 and 2, a front camera 10 (an example of an imaging device) is provided above and behind the windshield 6. The front camera 10 is an imaging device that captures (photographs) an exterior space SP2 (in this embodiment, the space in front of the vehicle 1) from the interior space SP1 through the windshield 6. The front camera 10 is a digital camera that uses a solid-state imaging element such as a CCD or CMOS. The front camera 10 includes a lens 10A that converges light incident from the front through the windshield 6, and a sensor (not shown) that converts the light converged by the lens 10A into an electrical signal.

As shown in FIG. 2, the front camera 10 is attached to the inner surface of the windshield 6 via a bracket 11. The bracket 11 has a fixed frame 12 fixed to the inner surface of the windshield 6 and a hood 13 that protrudes from the fixed frame 12 toward the rear lower side (interior side of the vehicle). When viewed from the front of the vehicle 1, the fixed frame 12 overlaps with black ceramic 6A printed on the interior surface of the windshield 6.

The hood 13 is provided behind the windshield 6 (inside the vehicle). The hood 13 is installed to prevent objects within the vehicle interior space SP1 from appearing in the image captured by the front camera 10, for example, due to light reflected from the objects within the vehicle interior space SP1 being reflected by the windshield 6. The hood 13 may be provided with a stray light shield (SLS) to prevent light reflected by the hood 13 from entering the front camera 10. The hood 13 defines the lower edge of the space (hereinafter referred to as the visual field space S) through which light entering the front camera 10 from the external space SP2 passes. The front camera 10 captures the external space SP2 through a portion of the windshield 6 located within the visual field space S of the front camera 10 (hereinafter referred to as the visual field region R).

Referring to FIG. 3, the vehicle 1 includes a propulsion device 14, a braking device 15, a steering device 16, an HMI (Human Machine Interface) 17, a navigation device 18, an air conditioning device 20, a heating device 21, an external sensor 23, a vehicle sensor 24, and a control device 26. The heating device 21, the vehicle sensor 24, and the control device 26 constitute an anti-fogging system X for the vehicle 1.

The propulsion device 14 is a device that provides driving force to the vehicle 1. The propulsion device 14 includes, for example, an internal combustion engine such as a gasoline engine or a diesel engine and/or an electric motor.

The brake device 15 is a device that applies braking force to the vehicle 1. The brake device 15 includes, for example, a brake caliper that presses a pad against a brake rotor, and an electric cylinder that supplies hydraulic pressure to the brake caliper.

The steering device 16 is a device that changes the steering angle of the wheels. The steering device 16 includes, for example, a rack-and-pinion mechanism that steers the wheels and an electric motor that drives the rack-and-pinion mechanism.

The HMI 17 is a device that notifies the occupant of various information and accepts input operations from the occupant. The HMI 17 includes, for example, a power switch for switching the power state of the vehicle 1, a touch panel, a sound generation device (speaker), a sound acquisition device (microphone), etc.

The navigation device 18 is a device that provides route guidance to the destination of the vehicle 1. The navigation device 18 includes an input device that accepts input operations from the occupant. This input device may be configured as part of the HMI 17, or may be provided separately from the HMI 17.

The navigation device 18 stores map information for the area in which the vehicle 1 travels. The navigation device 18 determines the current position (latitude and longitude) of the vehicle 1 based on GNSS signals (e.g., GPS signals) received from artificial satellites. The navigation device 18 sets a driving route from the departure point (e.g., current position) of the vehicle 1 to the destination based on the map information, the current position of the vehicle 1, and the destination of the vehicle 1 input by the occupant into the input device.

The navigation device 18 is connected to various servers 30 via a network N such as the Internet. Each server 30 is a computer equipped with a CPU, memory such as ROM or RAM, and a storage device such as an HDD or SSD. Each server 30 provides corresponding information in response to a request from the navigation device 18. The server 30 to which the navigation device 18 is connected may include a weather server 30A that provides weather forecast information for the driving route in response to a request from the navigation device 18. The weather forecast information includes the weather, temperature, and wind speed predicted for each point on the driving route. The weather forecast information may also include the amount of solar radiation, temperature, humidity, etc. predicted for each point on the driving route.

The air conditioning unit 20 is configured as a so-called car air conditioner that heats, cools, and ventilates the interior space SP1. The air conditioning unit 20 cools the interior space SP1 by using the heat of vaporization of the refrigerant to cool the air and sending that air into the interior space SP1. The air conditioning unit 20 heats the interior space SP1 by using heat generated by the propulsion unit 14, etc., and sending that air into the interior space SP1. Alternatively, the air conditioning unit 20 may be configured to heat the interior space SP1 by using an electric heater, heat pump, etc. to heat the air and sending that air into the interior space SP1.

The air conditioning unit 20 includes a duct connected to the interior space SP1 and the exterior space SP2, an evaporator and heater core installed in the duct, a blower fan that generates airflow within the duct, and an electric motor that drives the blower fan. The air conditioning unit 20 is configured to allow switching of the set temperature, air volume (blower fan rotation speed), and air conditioning mode.

The heating device 21 is a device that heats the windshield 6 to prevent fogging of the windshield 6, and includes a heater 31 for performing the heating. In this embodiment, the heater 31 heats the viewing area R of the windshield 6 to prevent fogging of the viewing area R. In this way, fogging of the viewing area R (i.e., the portion of the windshield 6 required for the front camera 10 to capture an image of the exterior space SP2) is prevented, thereby preventing the front camera 10 from being unable to capture an image of the exterior space SP2.

The heater 31 is composed of a heating wire 33. As shown in FIG. 2, the heating wire 33 is fixed to the inner surface of the windshield 6 and is arranged along the periphery of the viewing space S of the front camera 10, specifically, along the outer edge of the viewing area R. Note that in other embodiments, the heating wire 33 may be built into the windshield 6 or fixed to the bracket 11.

The external sensor 23 is a sensor that detects objects (such as obstacles on the roadway of the vehicle 1, lane markings, and vehicles ahead) present in the vehicle exterior space SP2. As shown in FIG. 3, the external sensor 23 includes the front camera 10 described above, a sonar 38, and an exterior camera 39 that captures images of the left and right sides and rear of the vehicle 1 through the window.

The vehicle sensor 24 is a sensor for acquiring information related to temperature and other factors that may cause stress on the windshield 6, and detects the conditions of the interior space SP1 and exterior space SP2. The vehicle sensor 24 is connected to the control device 26 and outputs the detection results to the control device 26.

The vehicle sensors 24 include an exterior temperature sensor 40 provided on the vehicle body 2 and an interior camera temperature sensor 41 provided inside the front camera 10. The vehicle sensors 24 may further include an interior temperature sensor 42 provided inside the vehicle cabin.

The exterior temperature sensor 40 (also referred to as the exterior air temperature sensor) detects the temperature of the exterior space SP2 (an example of the state of the exterior space SP2; hereinafter referred to as the "exterior temperature"). The exterior temperature sensor 40 may be located, for example, near the front bumper or front grille. The exterior temperature sensor 40 may be configured, for example, as a thermistor whose resistance value changes depending on the exterior temperature (outside air temperature). The exterior temperature sensor 40 may also be configured as a resistance temperature detector or a thermocouple instead of a thermistor.

The camera internal temperature sensor 41 detects the temperature inside the front camera 10 (hereinafter referred to as the camera internal temperature). The camera internal temperature sensor 41 is preferably configured as a thermistor, whose resistance value changes with temperature. The camera internal temperature sensor 41 is preferably provided on a circuit board on which a solid-state imaging element is provided, and is preferably configured and arranged so that its resistance changes depending on the temperature of the memory or solid-state imaging element, for example. The camera internal temperature sensor 41 may also be configured as a resistance thermometer or thermocouple instead of a thermistor.

The interior temperature sensor 42 detects the temperature of the interior space SP1 (an example of the state of the interior space SP1; hereinafter referred to as the "interior temperature"). The interior temperature sensor 42 may be located, for example, inside the interior space SP1 (inside the vehicle cabin). The interior temperature sensor 42 may be configured as a thermistor whose resistance value changes depending on the interior temperature. The interior temperature sensor 42 may also be configured as a resistance temperature detector or a thermocouple instead of a thermistor.

As shown in FIG. 4, the control device 26 is an electronic control unit (ECU) configured by a computer equipped with a processor 26A such as a CPU (central processing unit) or MPU (microprocessor unit), a memory 26B such as ROM (read-only memory) or RAM (random access memory), and a storage device 26C such as an SSD (solid state drive) or HDD (hard disk drive). The control device 26 can perform various processes by having the processor 26A read necessary data and application software from the memory 26B or storage device 26C and execute predetermined arithmetic processing in accordance with the software. The control device 26 may be configured as a single piece of hardware, or as a unit consisting of multiple pieces of hardware.

As shown in FIG. 3, the control device 26 is connected to each component of the vehicle 1 via a communication network 43 such as a CAN (Controller Area Network), and controls each component of the vehicle 1. The communication network 43 may be composed of multiple networks, and may include, for example, a B-CAN and an F-CAN, which has a faster communication speed than a B-CAN.

The vehicle 1 is equipped with a battery 46. The battery 46 may be charged by regeneration using an electric motor, or may be charged by power from an ACG (alternator) provided in the gasoline engine.

The battery 46 functions as a voltage source that supplies power to various devices installed on the vehicle 1, including the propulsion device 14, braking device 15, HMI 17, navigation device 18, heating device 21, external sensor 23, vehicle sensor 24, and control device 26.

The control device 26 includes, as functional units, an external environment recognition unit 52, a driving control unit 53, an anti-fogging control unit 54, and a memory unit 57. At least some of the functional units of the control device 26 may be realized by hardware such as an LSI, ASIC, or FPGA, or by a combination of software and hardware.

The external environment recognition unit 52 of the control device 26 recognizes the position of targets (obstacles on the roadway of the vehicle 1, lane markings, vehicles ahead, etc.) present in the vehicle exterior space SP2 based on the detection results of the external environment sensor 23. For example, the external environment recognition unit 52 recognizes the position of targets present in front of the vehicle 1 by analyzing changes in density values in the image captured by the front camera 10.

The driving control unit 53 of the control device 26 controls the driving of the vehicle 1 based on the positions of targets (obstacles on the roadway of the vehicle 1, lane markings, vehicles ahead, etc.) recognized by the external environment recognition unit 52. The driving control performed by the driving control unit 53 includes various driving controls (driving control equivalent to SAE autonomous driving levels 1 and 2) for configuring an advanced driver assistance system (ADAS). In other embodiments, the driving control performed by the driving control unit 53 may also include various driving controls (driving control equivalent to SAE autonomous driving levels 3 or higher) for achieving autonomous driving (AD).

Various types of driving control that realize ADAS include, for example, lane keeping control and vehicle-in-front control. In lane keeping control, the driving control unit 53 controls the steering device 16 so that the vehicle 1 travels along a reference position (e.g., the center of the lane's width) within a lane defined by dividing lines. In vehicle-in-front control, the driving control unit 53 controls the propulsion device 14 and braking device 15 so that the distance between the vehicle 1 and the vehicle in front is maintained within a predetermined range.

The defogging control unit 54 of the control device 26 controls the output of the heater 31 of the heating device 21 based on the detection results of the vehicle sensor 24 to prevent fogging of the front windshield 6.

The defogging control unit 54 includes a heater control unit 55 and a heater control determination unit 56.

The heater control unit 55 applies voltage to the heater 31 to perform various processes that control the amount of heat output from the heater 31.

The heater control unit 55 is configured to perform a de-icing process that maintains a predetermined voltage (hereinafter referred to as the supply voltage) applied to the heater 31, an anti-fogging process that applies a voltage pulse to the heater 31 using PWM (Pulse Width Modulation) control, and a stop process that maintains the heater 31 without applying voltage.

In PWM control, the defogging control unit 54 generates a voltage pulse that repeatedly switches on and off by repeatedly switching on and off, and applies it to the heater 31. At this time, the defogging control unit 54 generates a voltage pulse with a constant period that becomes the supply voltage when on (High) and becomes 0 V when off. In PWM control, the defogging control unit 54 controls the output from the heater 31 (more specifically, the amount of heat generated per unit time by the heater 31) by changing the proportion of time that the voltage pulse remains on per period, i.e., the duty ratio.

The heater control unit 55 determines whether or not predetermined conditions are met based on the detection results of the vehicle sensor 24, and when it determines that the predetermined conditions are met, it instructs the heater control unit 55 to execute the corresponding processing.

The heater control determination unit 56 determines whether the conditions for performing the thawing process (hereinafter referred to as the thawing conditions) are met based on the detection results of the vehicle exterior temperature sensor 40 and the camera interior temperature sensor 41. When the thawing conditions are met, the heater control unit 55 instructs the heater control unit 55 to perform the thawing process.

The heater control determination unit 56 determines whether the conditions for performing the defogging process (hereinafter, the defogging conditions) are met based on the detection results of the vehicle exterior temperature sensor 40 and the camera interior temperature sensor 41. When the defogging conditions are met, the heater control unit 55 instructs the heater control unit 55 to perform the defogging process.

The heater control determination unit 56 determines whether the conditions for performing the stop process (hereinafter, the stop conditions) are met based on the detection results of the vehicle exterior temperature sensor 40 and the camera interior temperature sensor 41. When the stop conditions are met, the heater control unit 55 instructs the heater control unit 55 to perform the stop process.

The storage unit 57 of the control device 26 is composed of the memory 26B and/or the storage device 26C. The storage unit 57 stores various information required for controlling the vehicle 1 and for controlling the heater 31 performed by the defogging control unit 54.

The information stored in the memory unit 57 includes, for example, dynamic map data. Dynamic map data includes static information, quasi-static information, quasi-dynamic information, and dynamic information. Static information includes three-dimensional map information with higher accuracy than the map information stored in the navigation device 18. Quasi-static information includes traffic regulation information, road construction information, and wide-area weather information. Quasi-dynamic information includes accident information, congestion information, and narrow-area weather information. Dynamic information includes traffic light information, nearby vehicle information, and pedestrian information. The control device 26 may connect to the high-accuracy map server 30B via the network N as appropriate and update the dynamic map data stored in the memory device 26C.

The information stored in the memory unit 57 includes various information required for the defogging control unit 54 to control the heater 31 (hereinafter referred to as heater control information).

The heater control information includes determination information indicating the relationship between the outside vehicle air temperature and the internal camera temperature and whether or not to perform the de-icing process. The determination information indicates whether the outside vehicle air temperature and the internal camera temperature meet the conditions for performing the de-icing process (hereinafter referred to as the de-icing conditions).

In this embodiment, the judgment information is represented by the true/false table shown in Figure 5. In Figure 4, True means that the thawing process will be performed (the thawing conditions are met), and False means that the thawing process will not be performed (the thawing conditions are not met). The boundary between the True region and the False region corresponds to the threshold value Th that determines whether or not the thawing process will be performed.

As shown in Figure 4, the threshold value Th is set to either remain constant or increase as the outside temperature decreases.

However, instead of a truth table, the memory unit 57 may store, as determination information, a predetermined map, formula, or the like that indicates the relationship between the outside vehicle temperature, the internal camera temperature, and whether or not the de-icing process should be performed.

<Output control processing>
After the vehicle 1 starts, the defogging control unit 54 of the control device 26 executes an output control process at predetermined time intervals (e.g., every minute) until the vehicle 1 is stopped. In the output control process, the defogging control unit 54 sets a voltage to be supplied to the heater 31, applies the voltage, and causes the heater 31 to generate heat (i.e., output heat from the heater 31). Details of the output control process will be described below with reference to FIG. 6 . However, although the following description will be given assuming that the defogging control unit 54, which is a functional unit, executes various processes, this means that the processor 26A of the control device 26 executes predetermined processes in accordance with software, thereby executing various processes as the defogging control unit 54.

In the first step ST1 of the output control process, the defogging control unit 54 acquires the outside vehicle temperature from the outside vehicle temperature sensor 40 and the internal camera temperature from the internal camera temperature sensor 41. Once acquisition is complete, the defogging control unit 54 references the determination information (true/false table) and determines whether the de-icing conditions are met based on the outside vehicle temperature and the internal camera temperature.

In this embodiment, the defogging control unit 54 obtains a corresponding threshold value Th (for example, when the outside temperature is -5°C, the threshold value Th is 20°C) based on the obtained outside temperature, and determines that the thawing conditions are met when the internal camera temperature is lower than that threshold value Th.

In addition, the defogging control unit 54 may refer to the corresponding column in the truth table (for example, when the temperature outside the vehicle is -5°C and the temperature inside the camera is 5°C, the column in the first row and second column of the truth table) to determine whether the defrosting conditions are met.

The defogging control unit 54 executes step ST2 when the outside vehicle temperature and the internal camera temperature meet the thawing conditions, and executes step ST3 when they do not.

In step ST2, the defogging control unit 54 executes the de-icing process. During the de-icing process, the defogging control unit 54 maintains the supply voltage applied to the heater 31. Once the de-icing process is initiated and the supply voltage is applied to the heater 31, the defogging control unit 54 terminates the output control process while the supply voltage is still applied to the heater 31 (i.e., while the de-icing process continues).

In step ST3, the defogging control unit 54 determines whether the defogging conditions are met (i.e., whether defogging processing should be performed). The defogging conditions may be, for example, an outside vehicle temperature greater than -40°C and less than 10°C. However, the defogging conditions are not limited to this.

The anti-fogging control unit 54 executes step ST4 if the anti-fogging conditions are met, and executes step ST5 if the anti-fogging conditions are not met.

In step ST4, the defogging control unit 54 performs the defogging process. In the defogging process, the defogging control unit 54 sets a duty ratio and applies a voltage pulse corresponding to that duty ratio to the heater 31. However, the defogging control unit 54 is configured to continue applying a voltage pulse corresponding to that duty ratio to the heater 31 until one of the following processes is started: the thawing process, the defogging process, or the stop process.

The anti-fogging control unit 54 sets the duty ratio to a value greater than 0 and less than 1 (less than 1) during anti-fogging processing.

The defogging control unit 54 may set the duty ratio to decrease as the camera's internal temperature increases from the threshold value Th. For example, when the difference between the camera's internal temperature and the threshold value Th is δT, the defogging control unit 54 may set the duty ratio to be exp(-δT/T0) (where T0 is an arbitrary constant).

The defogging control unit 54 starts the defogging process by applying a voltage pulse corresponding to the duty ratio to the heater 31, and then ends the output control process while continuing the defogging process.

In step ST5, the defogging control unit 54 determines that the stop condition is met and executes the stop process. During the stop process, the defogging control unit 54 stops the supply of voltage to the heater 31. Once the stop process is initiated, the defogging control unit 54 continues the stop process (i.e., stops the supply of voltage to the heater 31) and ends the output control process.

When the vehicle 1 is stopped, the defogging control unit 54 stops various processes such as de-icing process, defogging conditions, and stop process, and stops supplying voltage to the heater 31.

<Effects>
Next, a description will be given of the effects of the thus configured defogging system X. The defogging control unit 54 determines whether the defrosting conditions are met (ST1) based on the vehicle exterior temperature detected by the vehicle exterior temperature sensor 40 and the camera interior temperature detected by the camera interior temperature sensor 41. If the defrosting conditions are met, the defogging control unit 54 executes the defrosting process, and if the defrosting conditions are not met, the defogging control unit 54 executes the defogging process or the stop process.

The defogging control unit 54 maintains the supply voltage applied to the heater 31 during the defrosting process. On the other hand, the defogging control unit 54 sets the duty ratio to less than 1 during the anti-fogging process, and stops the heater 31 during the stop process. In other words, the defogging control unit 54 sets the duty ratio to 1 during the defrosting process, to a value greater than 0 and less than 1 during the anti-fogging process, and to 0 during the stop process. Therefore, when the defrosting conditions are not met, the defogging control unit 54 reduces the output of the heater 31 compared to when the defrosting conditions are met.

This limits the output of the heater 31 (the amount of heat emitted from the heater 31) when the ice-melting conditions are not met. This prevents the windshield 6 (more specifically, the panel that makes up the windshield 6) from heating up too quickly. This reduces the stress that may be applied to the windshield 6.

When the temperature outside the vehicle and the temperature inside the camera are both low, it is predicted that the windshield 6 will freeze. In particular, when the temperature outside the vehicle is low, it is necessary to continue outputting heat from the heater 31.

In this embodiment, the threshold value Th is set to increase as the temperature outside the vehicle decreases. As a result, when the temperature outside the vehicle is low, output from the heater 31 continues until the temperature inside the camera exceeds the threshold value Th. Therefore, the threshold value Th can be set appropriately so that ice on the outer surface of the windshield 6 can be melted when the temperature outside the vehicle is low.

In this way, by suppressing fogging of the front windshield 6, it is possible to reduce the number of situations in which driving control of the vehicle 1 cannot be performed based on the images captured by the front camera 10. Therefore, the present invention further improves traffic safety and contributes to the development of sustainable transportation systems.

<<Second Embodiment>>
The anti-fogging system X according to the second embodiment differs from the first embodiment in the conditions for executing the de-icing process, i.e., the de-icing conditions, but the other configurations are the same as those of the first embodiment. Therefore, a description of the other configurations will be omitted, and the following will describe the de-icing conditions according to the second embodiment.

The de-icing conditions in the second embodiment are determined based on the outside-vehicle temperature detected by the outside-vehicle temperature sensor 40 and the inside-vehicle temperature acquired by the inside-vehicle temperature sensor 42. In other words, in the second embodiment, the determination information indicates whether the outside-vehicle air temperature and the inside-vehicle temperature meet the conditions for executing the de-icing process.

Specifically, the determination information according to the second embodiment is represented by the true/false table shown in Figure 7. In Figure 7, True means that the thawing process is to be performed (the thawing conditions are met), and False means that the thawing process is not to be performed (the thawing conditions are not met). The boundary between the True region and the False region corresponds to the threshold value Th that distinguishes between whether or not the thawing process is to be performed.

As shown in Figure 7, the threshold value Th is set to either remain constant or decrease as the outside vehicle temperature decreases.

In the second embodiment, in the first step ST1 of the output control process, the defogging control unit 54 acquires the outside temperature from the outside temperature sensor 40 and the inside temperature from the inside temperature sensor 42. Once acquisition is complete, the defogging control unit 54 references the determination information (true/false table) and determines whether the de-icing conditions are met based on the outside temperature and the inside temperature.

For example, the defogging control unit 54 obtains a corresponding threshold value Th based on the obtained outside vehicle temperature (for example, when the outside vehicle temperature is -5°C, the threshold value Th is 10°C), and determines that the defrosting conditions are met when the inside vehicle temperature is lower than that threshold value Th.

As in the first embodiment, the defogging control unit 54 executes step ST2 when it determines that the thawing conditions are met, and executes step ST3 when it determines that the thawing conditions are not met.

<Effects>
Next, the effects of the thus configured defogging system X will be described. As in the first embodiment, when the defrosting conditions are not met, the output of the heater 31 (the amount of heat emitted from the heater 31) is limited. This makes it possible to prevent the windshield 6 (more specifically, the panel that constitutes the windshield 6) from being suddenly heated.

When the temperature outside the vehicle is low and the temperature inside the vehicle is also low, it is expected that ice will form on the windshield 6. Therefore, by increasing the output of the heater 31, ice can be properly melted.

When the air conditioning unit 20 is operating, the temperature difference between the outside and inside temperatures is small, and it is predicted that the temperature difference between the outside and inside temperatures will increase as the operating time of the air conditioning unit 20 increases. On the other hand, as the operating time of the air conditioning unit 20 increases, the inside temperature will rise, and it is predicted that the windshield 6 will warm up, causing ice adhering to the windshield 6 to melt.

In this embodiment, the true/false table is configured so that supply voltage is applied to the heater 31 (i.e., the duty ratio is set to 1) until a sufficient temperature difference is achieved between the temperature outside the vehicle and the temperature inside the vehicle. As shown in Figure 7, the threshold value Th is configured to decrease as the temperature outside the vehicle decreases. This allows the threshold value Th to be appropriately set based on the operating time of the air conditioning device 20.

This concludes the explanation of specific embodiments, but the present invention is not limited to the above embodiments and modifications, and can be implemented in a wide variety of ways.

In the above embodiment, an example was described in which the driving control unit 53 of the vehicle 1 performs driving control related to ADAS and AD, but it is not essential to the present invention that the driving control unit 53 perform driving control. The anti-fogging system X may have any configuration as long as it includes a control device 26 equipped with an anti-fogging control unit 54, and the control device 26 controls the output of the heater 31 to prevent fogging of windows such as the windshield 6 and prevent the generation of stress inside the windshield 6. For example, the anti-fogging control unit 54 may be configured as a computer (control device) different from the computer that performs driving control, etc. The control device 26 that constitutes the anti-fogging control unit 54 may be housed inside the front camera 10.

In the above embodiment, an anti-fogging system X was described that defogs the portion of the windshield 6 located in front of the front camera 10, but the present invention is not limited to this form. The present invention can be applied to an anti-fogging system X that defogs the portion of the window located within the field of view of an imaging device that captures images of the exterior space SP2 from the interior space SP1 of the vehicle.

In the above embodiment, as shown in Figures 5 and 6, the determination information showing the relationship between the outside vehicle air temperature and the internal camera temperature (or the outside vehicle temperature and the internal vehicle temperature) and whether or not to perform the de-icing process was represented by a true/false table, but this is not limited to this form. The determination information may also be represented by a map, graph, etc. For example, as shown in Figure 8, the determination information may be represented by a map with the outside vehicle air temperature on the horizontal axis and the internal camera temperature (internal vehicle temperature) on the vertical axis.

In the above embodiment, the control device 26 was configured to change the output of the heater 31 by changing the duty ratio, but the control device 26 may also be configured to change the output of the heater 31 by changing the voltage applied to the heater 31.

In the above embodiment, the control device 26 was configured to determine in ST1 whether the de-icing conditions are met, i.e., whether de-icing control should be performed, based on the temperature outside the vehicle and the temperature inside the camera, or the temperature outside the vehicle and the temperature inside the vehicle (see Figures 6 and 8). However, this is not limited to this configuration. For example, the control device 26 may obtain information via the weather server 30A and determine whether de-icing is required (whether the de-icing conditions are met).

A condensation sensor 60 (see Figure 2) may be provided on the inside of the front windshield 6, and the control device 26 may be configured to determine whether to perform de-icing control based on the detection results of the condensation sensor 60, the outside temperature detected by the outside temperature sensor 40, and the image captured by the front camera 10.

Specifically, the control device 26 first determines whether the outside-vehicle temperature acquired by the outside-vehicle temperature sensor 40 is below a predetermined threshold (a temperature threshold at which freezing or condensation may occur). The control device 26 executes a stop process when the outside-vehicle temperature is above the threshold. When the outside-vehicle temperature is below the threshold, the control device 26 acquires an image acquired by the front camera 10. The control device 26 then performs image color analysis of the image acquired by the front camera 10 to determine whether the field of view R of the windshield 6 is whitened. Next, when the field of view R is whitened and condensation is detected by the condensation sensor 60, the control device 26 determines that the field of view R is fogged and performs defrosting control. When the field of view R is whitened and condensation is not detected by the condensation sensor 60, the control device 26 determines that the windshield 6 is frozen and performs a defrosting process. The control device 26 grays out the image acquired by the front camera 10, acquires a shading distribution, and determines whether the field of view R is whitened based on the shading distribution.

Additionally, a capacitance sensor 62 (see FIG. 2) may be provided on the windshield 6 to detect ice on the windshield 6. The control device 26 may determine whether or not the windshield 6 is frozen based on the capacitance detected by the capacitance sensor 62. The capacitance sensor 62 may include, for example, two electrodes (e.g., comb-shaped electrodes) provided on the windshield 6 and an electronic circuit for detecting the impedance (capacitance) between the two electrodes. The control device 26 may determine whether or not the exterior of the windshield 6 is frozen based on the impedance detected by the capacitance sensor 62. The two electrodes of the capacitance sensor 62 are preferably disposed between the glass and the black ceramic 6A. In this way, by disposing the electrodes constituting the capacitance sensor 62 between the glass and the black ceramic 6A, it is possible to reduce the effect of condensation on the interior side of the windshield 6 on the detection results of the capacitance sensor 62.

1: Vehicle 3: Vehicle compartment 6: Front window (an example of a window member)
10: Front camera (example of camera)
26: Control device 31: Heater 40: Vehicle exterior temperature sensor 41: Camera interior temperature sensor 42: Vehicle interior temperature sensor R: Viewing area X: Anti-fogging system

Claims (3)

An anti-fogging system for a camera that captures an image of the outside of a vehicle through a predetermined field of view set on a vehicle window, comprising:
a heater for heating the viewing area;
an outside temperature sensor that detects the temperature outside the vehicle compartment as the outside temperature;
a dew condensation sensor provided on the interior side of the window;
a control device that controls the heater based on the outside temperature acquired by the outside temperature sensor, the detection result by the condensation sensor, and the image captured by the camera,
The control device
When the outside temperature detected by the outside temperature sensor is less than a temperature threshold value,
determining whether the field of view is whitened based on the captured image acquired from the camera;
When the field of view is whitened and condensation is detected by the condensation sensor, an anti-fogging process is performed;
When the field of view is white and no condensation is detected by the condensation sensor, the anti-fogging system performs a de-icing process by setting the heater output higher than that of the anti-fogging process . An anti-fogging system for a camera that captures an image of the outside of a vehicle through a predetermined field of view set on a vehicle window, comprising:
a heater for heating the viewing area;
an outside temperature sensor that detects the temperature outside the vehicle compartment as the outside temperature;
a capacitance sensor having two electrodes and a detection unit that detects capacitance between the two electrodes;
a control device that controls the heater based on a detection result of the capacitance sensor,
The control device determines whether a predetermined thawing condition is satisfied based on the capacitance detected by the detection unit, and when the thawing condition is not satisfied, reduces the output of the heater compared to when the thawing condition is satisfied,
The window includes a panel made of glass and black ceramic printed on the interior surface of the panel so as to surround the viewing area,
The two electrodes are respectively provided between the panel and the black ceramic. the control device is capable of applying a voltage pulse that repeatedly turns on and off to the heater;
3. The anti-fogging system according to claim 1 , wherein the output of the heater is changed by changing the duty ratio of the voltage pulse.