JP2023031980A - On-vehicle camera - Google Patents

Abstract

To increase the normal operating time of an on-vehicle camera by shortening a period required for recovery of the stopped on-vehicle camera while reducing failures caused by a temperature rise in the on-vehicle camera.SOLUTION: An on-vehicle camera includes imaging means, temperature detection means, vehicular speed detection means, and control means that is configured to stop or limit a function of the on-vehicle camera in a case where an internal temperature of the on-vehicle camera is higher than a first temperature, and is incorporated in the vehicle for imaging the outside of the vehicle. Further, in a case where the internal temperature of the on-vehicle camera is equal to or lower than a second temperature being lower than the first temperature, the control means disengages stopping or limiting of the function of the on-vehicle camera, and the temperature detection means and the vehicular speed detection means are configured to function even in the case where the function of the on-vehicle camera is stopped or limited by the control means. Further, the second temperature is changed, on the basis of a vehicle parameter that is a parameter including at least a vehicular speed, so as to approach the first temperature as a radiation efficiency of the on-vehicle camera increases.SELECTED DRAWING: Figure 3

Description

The present invention relates to an in-vehicle camera. Specifically, the present invention provides an in-vehicle camera capable of increasing the normal operating time of the in-vehicle camera by shortening the period required for the on-vehicle camera to recover from a stop while reducing failures caused by temperature rise of the in-vehicle camera. Regarding.

In an on-vehicle camera used for vehicle control, for example, the temperature of the on-vehicle camera rises due to the external environment (e.g., air temperature and solar radiation) and/or the heat generated due to operation (self-heating), exceeding the guaranteed operating temperature, and the on-vehicle camera There are times when problems arise that lead to breakdowns. In order to reduce such problems, there is known a technique of stopping the vehicle-mounted camera by turning off the power supply when the temperature of the vehicle-mounted camera exceeds a predetermined threshold (for example, Patent Document 1 and See Patent Document 2).

In the conventional technology as described above, the vehicle-mounted camera is restored (turned on) when a state in which it is estimated that the vehicle-mounted camera has been cooled to a temperature equal to or lower than a predetermined threshold is detected. is known (see, for example, Patent Literature 1). In this case, the temperature of the onboard camera itself cannot be detected because the power supply of the onboard camera is off when the onboard camera is restored. Therefore, the temperature of the on-board camera is estimated based on the elapsed time since the on-board camera was stopped, the speed of the vehicle equipped with the on-board camera (vehicle speed), and vehicle information such as the outside temperature of the vehicle. The in-vehicle camera is reset when it is determined that the temperature has decreased below the threshold. In this way, when the on-board camera is restored, the temperature of the on-board camera that is estimated based on vehicle information, etc. is used instead of the actually detected temperature of the on-board camera. It should be set low. As a result, the period required for turning off the power of the on-board camera and then turning it back on (from stopping the on-board camera to restarting it) becomes longer, and there is a risk that the normal operating time of the on-board camera will be excessively shortened. .

By the way, the temperature threshold (stop temperature) of the in-vehicle camera when turning off the power of the in-vehicle camera and the threshold (recovery temperature) of the temperature of the in-vehicle camera when turning on the power of the in-vehicle camera are the same (hysteresis control is not performed), as illustrated in FIG. 4, the on-vehicle camera is frequently turned off and on (the on-vehicle camera is frequently stopped and restarted). In the technical field, it is widely practiced to set the recovery temperature lower than the stop temperature (perform hysteresis control) for the purpose of reducing such problems. As illustrated in FIG. 5, by performing the hysteresis control, the vehicle-mounted camera is switched between off and on (the vehicle-mounted camera is stopped and restarted more frequently than when the hysteresis control is not performed as illustrated in FIG. 4). repeated) can be longer (see thick double-headed arrow). However, the lower the temperature threshold of the dash camera when turning on the dash camera in this way, the longer it takes for the dash camera to turn off and then on again. (until the camera is restored) will be even longer, and there is a risk that the normal operation time of the vehicle-mounted camera will be further excessively shortened.

As described above, in this technical field, it is possible to increase the normal operating time of an on-board camera by shortening the period required for the on-board camera to recover from a stop while reducing failures caused by temperature rise of the on-board camera. There is a demand for technology to

Japanese Patent Application Laid-Open No. 2006-151301 JP 2020-191575 A

As mentioned above, in this technical field, it is possible to increase the normal operation time of the on-board camera by shortening the period required for the on-board camera to recover from the stop while reducing the failure caused by the temperature rise of the on-board camera. There is a demand for technology to

Therefore, as a result of intensive research, the present inventors have found that even when the function of the on-vehicle camera is stopped or restricted due to the temperature rise of the on-vehicle camera, the detection of the temperature of the on-vehicle camera is continued and the function of the on-vehicle camera is restored. It has been found that the above problem can be solved by appropriately changing the threshold value (recovery temperature) according to parameters such as vehicle speed.

Specifically, an in-vehicle camera according to the present invention (hereinafter sometimes referred to as a "camera of the present invention") is an in-vehicle camera that is mounted on a vehicle and captures an image of the exterior of the vehicle, and includes imaging means; It comprises temperature detection means for detecting the internal temperature of the on-board camera, vehicle speed detection means for detecting the speed of the vehicle in which the on-board camera is mounted, and control means for controlling the operating state of the on-board camera. The control means is configured to stop or limit the function of the onboard camera when the internal temperature of the onboard camera is higher than a first temperature that is a predetermined threshold.

The temperature detection means is configured to detect the internal temperature of the on-board camera even when the function of the on-board camera is stopped or restricted by the control means. The vehicle speed detection means is configured to detect the vehicle speed even when the function of the vehicle-mounted camera is stopped or restricted by the control means. Furthermore, the control means is configured to release the suspension or restriction of the function of the vehicle-mounted camera when the internal temperature of the vehicle-mounted camera is equal to or lower than a second temperature, which is a predetermined threshold lower than the first temperature. In addition, the second temperature is changed so as to approach the first temperature as the heat radiation efficiency from the vehicle-mounted camera increases, based on vehicle parameters including at least vehicle speed.

As described above, in the camera of the present invention, the second temperature (recovery temperature), which is the threshold value of the internal temperature when stopping or releasing the limitation of the function of the on-board camera (recovering the on-board camera), is the heat dissipation from the on-board camera. Changed so that the higher the efficiency, the higher. Therefore, according to the camera of the present invention, it is possible to increase the normal operation time of the on-vehicle camera by shortening the period required for the on-vehicle camera to recover from the stop while reducing failures caused by the temperature rise of the on-vehicle camera.

Other objects, features and attendant advantages of the present invention will be readily understood from the description of each embodiment of the present invention described with reference to the following drawings.

4 is a schematic graph illustrating the relationship between the heat transfer coefficient of the windshield and the vehicle speed; 4 is a schematic graph illustrating changes in transition of the internal temperature of the vehicle-mounted camera according to the present invention (camera of the present invention) due to differences in vehicle speed and return temperature (second temperature). 4 is a flowchart illustrating the flow of each process included in an internal temperature control routine executed in the camera of the present invention; 5 is a schematic graph showing changes in internal temperature when hysteresis control is not performed and stopping and returning of the vehicle-mounted camera are frequently repeated; 5 is a schematic graph showing changes in the internal temperature when hysteresis control is performed and the period in which the stop and return of the vehicle-mounted camera are repeated becomes longer.

A vehicle-mounted camera according to the present invention (camera of the present invention) will be described in detail below with reference to the drawings.

As described above, in the conventional in-vehicle camera (hereinafter sometimes referred to as "conventional camera"), the temperature is estimated based on vehicle information, etc., instead of the temperature actually detected by the in-vehicle camera. When the temperature of the on-vehicle camera becomes equal to or lower than a predetermined threshold value, the on-vehicle camera is restored. For this reason, the threshold value is set low in consideration of the temperature estimation accuracy of the on-board camera, so the period required for the on-board camera to restart after being stopped becomes longer, and the normal operating time of the on-board camera becomes excessive. It is likely to be shortened. Moreover, this tendency becomes more conspicuous when hysteresis control is performed.

On the other hand, the camera of the present invention is an in-vehicle camera that is mounted on a vehicle and captures an image of the outside of the vehicle, as described above. Such an in-vehicle camera takes, for example, an image in front of and/or around the vehicle, and the image is used for various vehicle controls such as collision avoidance. Typically, the camera of the present invention is attached near the upper end of the inner side of the windshield of the vehicle (on the passenger compartment side) and captures an image centered on the front of the vehicle, like the conventional camera. However, the mounting position of the in-vehicle camera is not limited to the above, and is not particularly limited as long as it is possible to obtain the effect of increasing the cooling efficiency as the vehicle speed increases, as will be described later.

The camera of the present invention comprises imaging means, temperature detection means for detecting the internal temperature of the vehicle-mounted camera, vehicle speed detection means for detecting the vehicle speed of the vehicle in which the vehicle-mounted camera is mounted, and control means for controlling the operating state of the vehicle-mounted camera. , provided. The image capturing means is not particularly limited as long as it can capture an image that can be used in intended applications such as vehicle control as described above. A specific example of the imaging means is a digital camera using a CCD (Charged Couples Device) or a CMOS (Complementary Metal Oxide Semiconductor) as an imaging element.

The temperature detection means is not particularly limited as long as it can detect the internal temperature of the vehicle-mounted camera, and for example, thermocouples and the like widely used in the relevant technical field can be adopted. Also, the internal temperature of the vehicle-mounted camera is not limited to the temperature at a specific location of the vehicle-mounted camera as long as it has a correlation with the temperature of the components of the vehicle-mounted camera that may malfunction due to temperature rise. Specifically, the internal temperature of the vehicle-mounted camera includes, for example, the temperature of an IC chip and/or circuit board contained inside the vehicle-mounted camera, the surface temperature of the housing of the vehicle-mounted camera, and the temperature of the air inside the vehicle-mounted camera. means

The vehicle speed detection means is not particularly limited as long as it can detect the vehicle speed of the vehicle in which the on-board camera is mounted. can do.

The control means is configured to stop or limit the function of the onboard camera when the internal temperature of the onboard camera is higher than a first temperature that is a predetermined threshold. Such functions as control means can be realized by, for example, an electronic control unit (ECU: Electronic Control Unit) provided in the vehicle-mounted camera. The ECU has a microcomputer as a main part, and has an input port for receiving detection signals from components such as temperature detection means, and an output for transmitting instruction signals to components such as the power supply unit of the vehicle-mounted camera. Equipped with ports, etc. The microcomputer includes, for example, a CPU and data storage devices such as ROM and RAM. The CPU receives various detection signals, executes various arithmetic processes, and transmits various instruction signals based on instructions (programs) stored in the ROM, thereby realizing various functions. . The ECU can realize the function as a control means in this manner.

The first temperature is a temperature corresponding to the internal temperature of the vehicle-mounted camera detected by the temperature detecting means when the temperature of the components of the vehicle-mounted camera that may fail due to temperature rise exceeds the guaranteed operating temperature. The first temperature can be appropriately determined in consideration of, for example, a detection error by the temperature detection means and/or a further temperature rise during the period required for the control means to stop or limit the function of the vehicle-mounted camera.

Stopping or limiting the functions of the vehicle-mounted camera by the control means is not necessarily limited to stopping or limiting all functions of the vehicle-mounted camera, as long as further heat generation inside the vehicle-mounted camera can be reduced. That is, the functions of the on-vehicle camera that are stopped or limited by the control means are, for example, components of the on-vehicle camera that are likely to break down due to temperature rise and/or that generate a large amount of heat during operation. It may be a function of a part of the component. In addition, stopping or limiting the function of the on-board camera by the control means does not necessarily mean that, for example, power supply to all or part of the components of the on-board camera can be reduced as long as it is possible to reduce further heat generation inside the on-board camera. It is not limited to stopping by interruption or the like. In other words, stopping or restricting the function of the vehicle-mounted camera by the control means may reduce the load on all or part of the components of the vehicle-mounted camera, such as reducing the processing by changing the operation mode of all or part of the components of the vehicle-mounted camera. It also includes the reduction of

However, in the camera of the present invention, the temperature detection means is configured to detect the internal temperature of the on-board camera even when the function of the on-board camera is stopped or restricted by the control means. As a result, in the camera of the present invention, the internal temperature of the vehicle-mounted camera actually detected by the temperature detection means is used instead of the internal temperature of the vehicle-mounted camera estimated based on the vehicle information, etc., as in the conventional camera described above. , the function of the vehicle-mounted camera can be stopped or restricted (the vehicle-mounted camera can be restored).

That is, in the camera of the present invention, the control means cancels the suspension or restriction of the functions of the vehicle-mounted camera when the internal temperature of the vehicle-mounted camera is equal to or lower than the second temperature, which is a predetermined threshold lower than the first temperature. is configured to That is, the camera of the present invention performs hysteresis control. The second temperature is higher than the first temperature so as not to frequently switch between stopping or limiting the function of the onboard camera and releasing the stop or the limitation (the stopping and returning of the onboard camera are frequently repeated). is set to a lower temperature. In other words, even if the suspension or restriction of the function of the vehicle-mounted camera is canceled at that time and the internal temperature of the vehicle-mounted camera resumes rising, the second temperature remains within a sufficiently long period of time. The temperature is set to be lower than the first temperature so that the temperature can be maintained within the range of the first temperature or lower over the entire period.

By the way, as described above, the vehicle-mounted camera is typically mounted near the upper end portion inside (on the passenger compartment side) of the windshield of the vehicle. As the vehicle speed increases, heat radiation from the windshield due to contact with the air in front of the vehicle increases, so as shown in FIG. Therefore, the efficiency of heat dissipation from the vehicle-mounted camera through the windshield and/or the air in the vehicle interior around the windshield also increases as the vehicle speed increases.

As a result of the above, as shown in (a) of FIG. 2, the internal temperature of the vehicle-mounted camera becomes higher than the first temperature (stop temperature), and the function of the vehicle-mounted camera is stopped or restricted (the vehicle-mounted camera is stopped). The rate of decrease of the internal temperature of the vehicle-mounted camera in the later period is higher when the vehicle speed is high (high speed) than when the vehicle speed is low (low speed). Therefore, if the same second temperature (recovery temperature) is set for both low speed and high speed, the internal temperature of the on-vehicle camera becomes equal to or lower than the second temperature (recovery temperature), and the suspension or restriction of the on-vehicle camera function is released. The timing (in-vehicle camera returns) is earlier when the vehicle speed is high (high speed) than when the vehicle speed is low (low speed) (see the white arrow).

Furthermore, as shown in FIG. 2(a), the rate of increase of the internal temperature of the vehicle-mounted camera after recovery is lower when the vehicle speed is high (high speed) than when the vehicle speed is low (low speed). Therefore, if the same second temperature (recovery temperature) is set for both low speed and high speed, the internal temperature of the onboard camera becomes higher than the first temperature (stop temperature) again, and the function of the onboard camera is stopped or limited again. The timing (the in-vehicle camera is stopped again) is later when the vehicle speed is high (high speed) than when the vehicle speed is low (low speed). In this way, the normal operating time of the vehicle-mounted camera can be secured longer when the vehicle speed is high (high speed) than when the vehicle speed is low (low speed).

In particular, in the graph shown in FIG. 2(a), after time Tr (see the black circle), the difference between the internal temperature of the onboard camera and the first temperature (stop temperature) decreases when the vehicle speed is low (low speed ) when the vehicle speed is high (at high speed). That is, when the same second temperature (recovery temperature) is set for both low speed and high speed, the internal temperature of the on-vehicle camera when the vehicle speed is high (high speed) is higher than when the vehicle speed is low (low speed). 1 temperature (stop temperature). In other words, when the vehicle speed is high (high speed), the second temperature (recovery temperature), which is the same as when the vehicle speed is low (low speed), is too low in view of the rate of increase of the internal temperature of the on-vehicle camera. . Furthermore, in other words, when the vehicle speed is high (high speed), even if the second temperature (recovery temperature) is set higher than that at low speed, the internal temperature of the on-vehicle camera again becomes higher than the first temperature (stop temperature). It is possible to maintain the length of the period (normal operating time) until the function of the vehicle-mounted camera is stopped or limited (the vehicle-mounted camera is stopped) when the vehicle speed is low (at low speed).

Therefore, in the camera of the present invention, the second temperature is changed so as to approach the first temperature as the heat radiation efficiency from the vehicle-mounted camera increases, based on vehicle parameters including at least the vehicle speed of the vehicle. As described above, the in-vehicle camera is typically mounted near the upper end of the inside (vehicle side) of the windshield of the vehicle. The heat radiation efficiency from the camera increases as the vehicle speed increases. Therefore, in the camera of the present invention, the higher the vehicle speed, the closer the first temperature (stop temperature) is set as the second temperature (recovery temperature).

FIG. 2(b) is a schematic graph showing changes in internal temperature of the camera of the present invention when the vehicle speed is low (low speed) and when the vehicle speed is high (high speed). In the camera of the present invention, as described above, the second temperature (recovery temperature) at low speed is set closer (higher) to the first temperature than the second temperature (recovery temperature) at low speed (black arrow ). Therefore, the internal temperature of the camera of the present invention becomes equal to or lower than the second temperature, and the timing at which the stop or restriction of the functions of the camera of the present invention is released (the camera of the present invention returns) is earlier at high speed than at low speed. becomes even larger (see white arrow). As a result, compared to the case where the same second temperature is set at both low speed and high speed as shown in FIG. (see double arrow). As described above, according to the camera of the present invention, it is possible to shorten the period required for the on-vehicle camera to recover from its stop and increase the normal operation time of the on-vehicle camera while reducing the failure caused by the temperature rise of the on-vehicle camera. can.

Note that the "vehicle parameter" may be only the vehicle speed of the vehicle, or may further include other parameters that affect the heat radiation efficiency from the vehicle-mounted camera in addition to the vehicle speed. Specific examples of such other parameters include the outside air temperature of the vehicle. As a matter of course, the lower the outside air temperature of the vehicle, the higher the efficiency of heat dissipation from the vehicle-mounted camera via the above-described windshield and/or the air in the vehicle interior around the windshield. Therefore, the camera of the present invention further comprises outside air temperature detection means for detecting the outside air temperature of the vehicle, and changes the second temperature (return temperature) so that the higher the vehicle speed is, the closer it is to the first temperature (stop temperature). In addition, the second temperature (return temperature) may be changed so as to approach the first temperature (stop temperature) as the outside air temperature of the vehicle decreases.

Further, as the vehicle speed of the vehicle in which the camera of the present invention is mounted, an average value of vehicle speeds in a predetermined period may be used. When the outside air temperature of the vehicle is also used as the vehicle parameter as described above, the average value of the outside air temperature over a predetermined period may be used.

The correspondence relationship between the vehicle parameter and the second temperature (reset temperature) as described above is, for example, a combination of a plurality of second temperatures (reset temperature) corresponding to each range of vehicle speed divided into a plurality of ranges. can be stored in a data storage device such as a ROM constituting the control means as a two-dimensional data map. When the outside air temperature of the vehicle is also used as the vehicle parameter as described above, the correspondence relationship between the vehicle parameter and the second temperature (return temperature) is, for example, divided into a plurality of ranges of vehicle speed and a plurality of ranges. A three-dimensional data map as a combination of a plurality of second temperatures (recovery temperatures) corresponding to combinations of the respective ranges of the divided outside air temperatures is stored in a data storage device such as a ROM that constitutes the control means. be able to. Alternatively, the correspondence relationship between the vehicle parameter and the second temperature (recovery temperature) may be expressed by the control means as a function (calculation formula) having a variable of the vehicle parameter such as the vehicle speed or the combination of the vehicle speed and the outside temperature. may be stored in a data storage device such as a ROM that constitutes the

The operation of the camera of the present invention will now be described in detail below with reference to FIG. FIG. 3 is a flow chart showing an example of the flow of each process included in the internal temperature control routine executed in the camera of the present invention. When the power supply of the camera of the present invention is turned on (ON) and normal operation as an in-vehicle camera is started, the CPU constituting the control means operates according to a program stored in a data storage device such as a ROM constituting the control means. A control routine is repeatedly executed at predetermined time intervals. In the following description, a case will be described in which the vehicle speed is used as a vehicle parameter that serves as an index for changing the second temperature (recovery temperature).

When the control routine is started, first, in step S01, the internal temperature T of the camera of the present invention is acquired by the temperature detecting means. Next, in step S02, it is determined whether or not the internal temperature T is higher than the first temperature (stop temperature) T1. If the internal temperature T is equal to or lower than the first temperature T1, the determination in step S02 is "No", the process proceeds to step S09, and the normal operation of the vehicle-mounted camera is continued. On the other hand, when the internal temperature T is higher than the first temperature T1, it is determined as "Yes" in step S02, and the process proceeds to the next step S03, where the function of the vehicle-mounted camera is stopped or restricted.

When the function of the vehicle-mounted camera is stopped or restricted in step S03 as described above, the process proceeds to the next step S04, and the vehicle speed V of the vehicle equipped with the camera of the present invention is acquired by the vehicle speed detection means. Next, in step S05, a second temperature (recovery temperature) T2 is determined based on the vehicle speed V as the vehicle parameter described above. Specifically, as described above, the second temperature T2 is specified or calculated by the CPU constituting the control means based on the data map or function stored in the data storage device such as the ROM constituting the control means. .

Next, the process proceeds to step S06, and the internal temperature T of the camera of the present invention is acquired again by the temperature detecting means. Then, in the next step S07, it is determined whether or not the internal temperature T is equal to or lower than the second temperature T2. If the internal temperature T is higher than the second temperature T2, it is determined "No" in step S07, the process returns to step S04, the vehicle speed V of the vehicle is acquired again by the vehicle speed detection means, and step S05 and subsequent steps are performed. is repeated. On the other hand, if the internal temperature T is equal to or lower than the second temperature T2, it is determined as "Yes" in step S07, and the process proceeds to the next step S08, in which the function of the vehicle-mounted camera is stopped or restricted. normal operation of the camera is resumed). Then, the process proceeds to the next step S09, and the normal operation of the vehicle-mounted camera is continued.

As described above, in the camera of the present invention, the second temperature (recovery temperature), which is the threshold value of the internal temperature when stopping or releasing the limitation of the function of the on-board camera (recovering the on-board camera), is the heat dissipation from the on-board camera. Changed so that the higher the efficiency, the higher. Therefore, according to the camera of the present invention, it is possible to increase the normal operation time of the on-vehicle camera by shortening the period required for the on-vehicle camera to recover from the stop while reducing failures caused by the temperature rise of the on-vehicle camera.

It should be noted that the demand to increase the normal operation time by shortening the period required from the suspension or restriction of the function to the recovery while reducing the failure caused by the temperature rise accompanying the operation is not limited to the on-vehicle camera. For example, it is common to various in-vehicle devices that may cause problems such as failure due to temperature rise caused by the environment outside the vehicle and/or self-heating. That is, the present invention can be applied not only to an on-vehicle camera but also to various on-vehicle devices that have similar requirements.

Although several embodiments having particular configurations have been described with reference to the accompanying drawings for the purpose of illustrating the present invention, the scope of the present invention is limited to these exemplary embodiments. Needless to say, modifications can be made as appropriate within the scope of the claims and the matters described in the specification.

Claims (1)

An imaging means, a temperature detecting means for detecting an internal temperature of an in-vehicle camera, a vehicle speed detecting means for detecting a vehicle speed of a vehicle in which the on-vehicle camera is mounted, and a control means for controlling an operating state of the on-vehicle camera. ,
The control means is configured to stop or limit the function of the vehicle-mounted camera when the internal temperature is higher than a first temperature that is a predetermined threshold,
An in-vehicle camera that is mounted on a vehicle and captures an image of the exterior of the vehicle,
The temperature detection means is configured to detect the internal temperature even when the function of the vehicle-mounted camera is stopped or restricted by the control means,
The vehicle speed detection means is configured to detect the vehicle speed even when the function of the vehicle-mounted camera is stopped or restricted by the control means,
The control means is configured to release the suspension or restriction of the function of the vehicle-mounted camera when the internal temperature is equal to or lower than a second temperature that is a predetermined threshold lower than the first temperature,
The second temperature is changed based on vehicle parameters, which are parameters including at least the vehicle speed, so as to approach the first temperature as the heat radiation efficiency from the vehicle-mounted camera increases.
An in-vehicle camera characterized by:

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