JP2000025575A - Automatic defroster device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic defroster device which detects the brightness of an image and the low frequency component of the image to automatically operate a defroster. SOLUTION: An automatic defroster device which picks up the image of a part of a vehicle from an interior side over a glass by a TV camera 4, detects the foggy condition of a glass surface by the change in the image picking-up condition, and automatically operates a defroster 7, is provided with an image processing means to process the picked-up image of a part of the vehicle, a low frequency component calculating means to calculate the low frequency component through the image processing from the image processing means, a foggy condition detecting means which compares the low frequency component from the low frequency component calculating means with a pre-determined threshold to detect the foggy condition, and a defroster driving means to drive the defroster 7 according to the foggy condition from the foggy condition detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television camera, which captures an image of a part of a vehicle from the inside of a glass through a glass, detects a fogging state of the inner surface of the glass, and operates a defroster.
The present invention relates to an automatic defroster device.

[0002]

2. Description of the Related Art Conventionally, various devices have been proposed for detecting a preceding vehicle or detecting a white line or the like on a road surface to automatically drive the vehicle. However, these devices use a television camera as a detection sensor. To protect the TV camera, it is placed inside the windshield. Therefore, if the windshield is fogged, the discrimination ability is reduced. Therefore, it is necessary to detect the degree of the fogging and control so that the fogging is not excessive.

[0003]

On the other hand, a TV camera mounted on a vehicle captures various scenes. Therefore, when the images are subjected to Fourier transform, the frequency components fluctuate randomly. However, if attention is paid to a part of the image where the own vehicle is imaged, the fluctuation of the frequency component is small because the imaging target is specified. Further, when fogging occurs on the windshield, the edge of the hood or the like of the vehicle is blurred, so that high-frequency components are reduced and low-frequency components are increased. Therefore, the frequency component of the region of interest in the image sampled within a predetermined time is examined, and a certain low-frequency component is plotted on the vertical axis, and the sampling time or the number of times of sampling is plotted on the horizontal axis. You can know the cloudiness by looking at

However, the amount of low frequency components of an image captured by a television camera varies depending on the surrounding brightness, and the degree of fogging cannot be accurately detected merely by the degree of the vertical axis. In addition, it is necessary to detect the fogging and operate the defroster to remove the fogging. It is desirable to perform the operation.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an automatic defroster device which detects the brightness of an image and a low frequency component of the image at the brightness and automatically operates the defroster. It is.

[0006]

Means for solving the problem are as described in the claims. According to the present invention, a part of the vehicle is imaged through the glass from the inside of the vehicle with a television camera, and the glass may be a windshield, a rear window glass, or a side window glass.

[0007] Since there are many high-frequency waveforms in a bright case and many low-frequency waveforms in a dark case, the threshold value to be compared with the detected low-frequency component is determined based on how strong the low-frequency component is. As a value for determining whether or not it is cloudy, a table in which the brightness of the image is plotted on the vertical axis and the low frequency component is plotted on the horizontal axis is created in advance, and by detecting the brightness of the current image, the brightness is adjusted. Selected as corresponding.

For example, as shown in FIG. 4, the value of the low-frequency waveform on one screen every predetermined time (for example, 1/30 second) is plotted, and during a period from time t1 to time t2, the value becomes From the gradient X calculated from the change from V1 to the threshold value V2, the defroster changes depending on whether the value of the gradient Z calculated from the change from V2 to V3 during the period from time t2 to t3 is large or small. It is configured to change the operation state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified, and are merely illustrative examples. Not just.

FIG. 1 is a schematic diagram showing a schematic configuration of an automatic defroster control device according to the present invention, FIG. 2 is a diagram showing a screen imaged by a television camera, and FIG. 3 is a diagram showing a configuration of frequency components in an image. FIG. 4 is a diagram for explaining the calculation of the rate of increase in fogging, and FIG. 5 is a flowchart. In FIG.
In the vehicle 1, inside the windshield 2, above most of the drivers, outside the field of view α under normal driving conditions,
A television camera (hereinafter, referred to as a camera) 1 has an angle of view β so as to desire a subject partially different from the field of view α of the driver, and captures the preceding vehicle ahead of the vehicle and the hood 3 of the vehicle 1 within the angle of view. It is arranged as possible.

The image information from the camera 4 is connected to the image processing unit 6 so as to be able to be sent out, the image information taken in by the camera 4 is processed by the image processing unit 6, and a command signal from the image processing unit 6 is transmitted to a defroster device. The gas for differential is discharged from the duct 9. Further, the image processing unit 6 is configured to send a command signal to the wiper driving device 8 so that the wiper 5 can be driven.

Since the defroster device 7 has an air conditioner and is configured to control the humidity and temperature of the discharged gas, the defroster device 7 discharges a dry gas having a high temperature so as to vaporize quickly when the rate of increase in fogging is high. When the rate of increase in haze is low, a dry gas at a reduced temperature can be released.

The image processing section 6 extracts only an image of the area around the hood (area B in FIG. 2) from the image captured by the television camera 4, and detects the brightness of the image in that area. Threshold value selecting means for selecting a threshold value to be compared with the voltage value of the low frequency component. This threshold value selection means uses a low-frequency waveform because the image in the region B of the image 10 shown in FIG. 2 captured by the camera 4 has many high-frequency waveforms when it is bright and many low-frequency waveforms when it is dark. A table is created in advance by taking the brightness of the image as the vertical axis and the value of the low frequency component on the horizontal axis as a value of how strong the component is determined to be cloudy, and , The value of the low-frequency component corresponding to the brightness is selected as the threshold value.

As shown in FIG. 3, when the inner surface of the glass 2 in front of the camera 4 is free from fogging, there are many high-frequency components as shown by a waveform L1, and when there is fogging, the waveform L2 is used.
There are many low frequency components. Therefore, the image processing unit 6 further includes low frequency component calculation means for performing two-dimensional Fourier transform on the image of the region B in FIG. 2 to extract each frequency component. The frequency component is plotted as voltage on the vertical axis and time on the horizontal axis, the average of the low frequency component peak values is calculated, and the value is compared with the threshold value. And detecting means for detecting

Further, as shown in FIG. 4, the image processing section 6 plots the value of the low-frequency waveform on one screen every predetermined time (for example, 1/30 second), and during the time from time t1 to time t2. When the value changes from V1 to the threshold value V2, the gradient X is calculated by the following equation: X = (V2−V1) / (t2−t1) (1), and during a period from time t2 to t3. Means for calculating the gradient Z based on the change of the value from V2 to V3, Z = (V2−V3) / (t3-t2) (2) have.

The image processing section 6 determines whether the gradient Z is larger or smaller than X. If the gradient Z is larger than X, the high-temperature dry gas is released. A differential operating means for changing the operation state of the defroster so as to discharge the air is provided.

Next, the operation of the embodiment constructed as described above will be described with reference to the flowchart of FIG. When the engine of the vehicle 1 is driven, the camera 4 captures an image (2
0), and sends the image shown in FIG. The image processing unit 6 performs a calculation using only the image around the hood 3 which is the area B in FIG. 2 (21).

First, the average value of the brightness of the image is calculated (22), and the threshold value of the corresponding low-frequency component is obtained (23). Then, each frequency component is extracted by two-dimensional Fourier transform (24), and low frequency components are classified (2).
5) Compare the threshold with the low frequency component (26), and when there are more low frequency components than the threshold, fog is detected (2).
8) Yes.

On the other hand, the image processing section 6 extracts the low frequency component, calculates the gradient X and the gradient Z shown in FIG.
Are compared (29). If Z is larger than X, a high-temperature dry gas is released for a predetermined time (31). Otherwise, a low-temperature dry gas is released for a predetermined time (3).
0).

Steps 22 to 27 or 22 to 31 in the flowchart described above are performed at predetermined time intervals (for example, 10 to 20).
(Every second). Steps 30 and 31
Changes the temperature of the radiating gas, which may change the radiating time or the degree of drying.

[0021]

As described above, according to the present invention, even when the driver's field of view is not fogged and the glass on the entire surface of the camera is fogged, the defroster is automatically operated without the driver's operation. Can be driven. In addition, since the defroster operating state can be changed by calculating the fogging increase rate, an efficient differential operation can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an automatic defroster control device according to the present invention.

FIG. 2 is a diagram showing a screen imaged by a television camera.

FIG. 3 is a diagram illustrating a configuration of frequency components in an image.

FIG. 4 is a diagram illustrating calculation of a fogging increase rate.

FIG. 5 is a flowchart.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 2 Windshield 3 Bonnet 4 TV camera 6 Image processing part 7 Defroster device (defroster)

Claims (2)

[Claims] 1. An automatic defroster device which captures an image of a part of a vehicle from the inside of a vehicle through a glass with a television camera, detects a fogging state of the glass surface based on a change in the imaging state, and automatically operates a defroster. Image processing means for processing an image of a part of the vehicle; low frequency component calculation means for calculating a low frequency component by image processing from the image processing means; low frequency component from the low frequency component calculation means And a defroster driving means for driving the defroster according to the fogging state from the fogging state detecting means for detecting the fogging state. Features automatic defroster device. 2. The automatic defroster device according to claim 1, wherein said defroster driving means changes an operation state of said defroster in accordance with a degree of a fogging increase rate from said fogging state detecting means. .