Image detection system for a car.

BACKGROUND OF THE INVENTION

0001The present invention relates to an image detection system for a car, and in particular to a system for detecting and processing an image of a TV camera mounted on a car.

0002Heretofore, a system has been researched and developed in which a TV camera is mounted on a car as image detection means in order to find out obstacles on a forward or backward road of the car whereby an alarm is given to a driver, or a brake or a steering gear is automatically operated.

0003In this system, the TV camera can be mounted outside a car on one hand or inside a car on the other hand.

0004In the former case, it is disadvantageous in that raindrops in case of rain etc. or dust adheres to the surface of the lens of the TV camera, thereby disturbing a clear image.

0005A system for removing raindrops or dust which thus adheres to the surface of the lens of the TV camera is disclosed in Japanese Utility Model Application Laid-open No. 59-25528. However, this system is disadvantageous in that the lens of the TV camera should be rotated every time one desires to clean up raindrops or dust on the lens, which consumes time and disables an image taken meanwhile to be used.

0006Moreover, in the latter case where the TV camera is mounted outside a car, the TV camera per se is exposed to raindrops or dust so that the function thereof is easily deteriorated, resulting in a short life.

0007Therefore, the TV camera mounted inside a car is preferable to the one mounted outside a car.

0008However, it is also disadvantageous in that the image of a wiper for removing raindrops or dust intrudes into images detected by the TV camera. Therefore, if image processing is carried out as it is, a screen including the wiper image has no context with the adjacent screens so that the wiper image is to be detected as the nearest obstacle.

0009Thus, useless image processing with such an unavailable image, is carried out so as to cause the car erroneously to run in an automatic chase for an object.

SUMMARY OF THE INVENTION

0010Accordingly, it is an object of the present invention is to provide an image detection system for a car, with a TV camera mounted inside a car, which always makes clear images available under no influence of a wiper image.

0011According to the present invention, image detecting means continuously detects an image in front of a wiper and provides it for image updating-storing means and an change-over means in the form of data.

0012While the wiper is driven by driving means, when the drive angle of the driving means is detected by drive angle detecting means and provided for controlling means, the controlling means determines whether or not the detected drive angle of the wiper resides within a predetermined image pickup angle of the image detecting means and controls the change-over means to the side of the image updating-storing means. At the same time, the controlling means makes the updating-storing means provide the image as data output.

0013Thus, as shown in Fig.2, when the wiper resides outside the predetermined image pickup angle β₁ ∼ β₂, the dynamic image A detected by the image detecting means is directly provided as an output without change while when the wiper resides within the predetermined image pickup angle β₁ ∼ β₂, the dynamic image is unavailable so that an update image A' having been updated and stored in the image updating-storing means from the image detecting means so far is provided as an static image output.

0014Accordingly, a clear image is detected under no infulence of the wiper image even in rainy weather etc. and useless processing time can be removed in image processing and recognition etc. which are carried out for the provided image data.

0015According to another aspect of the present invention, normally, for the purpose of more accurate recognition (object chase) of visual information around the car with reference to the region of the detected image A as shown in Fig.2, the image detecting means is panned in the up, down, right and left directions within a certain fixed range by panning means to obtain a desired image.

0016Since the image detecting means is thus panned up, down, right and left by the panning means, the detected dynamic image A in Fig.2 is relatively moved according to the panning of the image detecting means even though the moving range of the wiper is fixed.

0017Therefore, if the panning range of the detected dynamic image A is such as shown by dotted lines in Fig.5, and in case where the detected dynamic image A is panned up, down, right and left by the panning means to e.g. the moved lower left position shown by oblique lines in Fig.6, it is found necessary that the wiper angle β₂ - β₁ of invalid image before panning is corrected for the processing to an angle γ₁ + γ₂.

0018Thereupon, the controlling means takes into account not only the drive angle of the driving means but also the pan angle from the panning means in which comparison and determination are made between the predetermined image pickup angle range corrected from the above noted predetermined image pickup angle range β₁ ∼ β₂ according to the pan angle and the drive angle of the driving means, thereby changing the dynamic image A over to the dynamic image A'.

0019Thus, even if the image detecting means is panned up, down, left and right anyhow, a clear image is obtained under no infulentce of the wiper image and whatever panning position the image detecting means is controlled to chase an object

0020According to a further aspect of the present invention, the scanning lines of an image detected by the image detecting means is preset in the direction substantially perpendicular to the moving (cleaning) direction of the wiper as shown in Fig.9.

0021Hereupon, since the wiper has a certain width as shown by oblique lines in Fig.9, image processing means which has taken in the detected image from the image detection means determines the scanning lines in the masking range for the wiper on the basis of the drive angle of the driving means, in a range which crosses the detected image of the wiper in scanning lines forming the detected image.

0022Then, the image processing means masks only the scanning lines in the masking range and provides them as blank data output and provides as an output the detected image with respect to other scanning lines as it is.

0023Hereby, when the wiper image intrudes into the image processing means in the form of the detected image, the portion of the scanning lines not crossing the image of the wiper is provided as an output while only the portion of the scanning lines crossing the same is masked and then provided as an output.

0024Also, according to the present invention, the image processing means, instead of the above masking operation, may substitute update static detected image in a valid portion of scanning lines not including the wiper image for the image of the scanning lines in range to be masked. Therefore, only the image of the scanning lines in the masked range is transplanted with static image data for the corresponding scanning lines among an update detected image not including the wiper image.

0025Thus, the deterioration of the quality of the image data due to the wiper image in rainy weather etc. is kept to an extremely limited, minimum area in which the wiper can exist on the detected image.

BRIEF DESCRIPTION OF THE DRAWINGS

0026The present invention will now be more apparent to those skilled in the art from the attached drawings in which; <ul id="ul0001" list-style="none"><li>Fig.1 is a block diagram showing a system arrangement of one embodiment of an image detection system for a car according to the present invention;</li><li>Fig.2 is a principle graph for the illustration of the relationship between an operating angle of a wiper and a detected image in the present invention;</li><li>Fig.3 is a flow chart showing the processing algorithm of a controller used in Fig.1;</li><li>Fig.4 is a block diagram of a system arrangement of another embodiment of an image detection system for a car according to the present invention;</li><li>Fig.5 is a graph for the illustration of a movable area of an image pickup area of a TV camera unit at the time of panning in the embodiment in Fig.4;</li><li>Fig.6 is a principle graph showing the relationship between an operating angle of a wiper and a movable image pickup area when the TV camera unit is panned in the embodiment in Fig.4;</li><li>Fig.7 is a flow chart showing the processing algorithm of a controller used in the embodiment in Fig. 4;</li><li>Fig.8 is a block diagram showing a system arrangement of a further embodiment of an image detection system for a car according to the present invention;</li><li>Fig.9 is a graph for the illustration of the relationship between the image of a wiper and scanning lines of a TV camera unit in the embodiment in Fig.8;</li><li>Fig.10 is a principle graph for the illustration of of a method for determining a scanning line range to be masked in the embodiment in Fig.8; and,</li><li>Fig.11 is a flow chart showing the masking algorithm of the embodiment in Fig.8.</li></ul>

DETAILED DESCRIPTION OF THE INVENTION

0027Fig.1 is a block diagram illustrating the arrangement of one embodiment of a distance measuring equipment according to the present invention, in which a non-reflecting protective glass 1 forms a front window (or a rear window under some circumstances) of a car (not shown), a wiper 2 is provided outside the protective glass 1 to clean up raindrops or dust which adheres to the protective glass 1, a wiper motor 3 is connected to the wiper 2 and serves as means for driving the wiper 2, and an angle sensor 4 is provided for detecting a drive angle of the wiper motor 3.

0028A controller 5 is connected to the angle sensor 4 and serves as change-over controlling means to generate a control signal on the basis of the output signal of the angle sensor 4. A TV camera unit 6 is provided to detect an image in front of the wiper 2 and includes an A/D (Analog/Digital) converter which converts the detected image into digital data. An image storage 7 which includes an image memory 71 and an output image memory 72 is connected to the TV camera unit 6 and serves as means for updating and storing (hereinafter abbreviated as updating-storing) the output data of the TV camera unit 6. A change-over switch 8 is connected to the TV camera unit 6 and the image storage 7, and changes the image storage 7 over to the TV camera unit 6. The image storage 7 and the change-over switch 8 are under control of the controller 5.

0029Next, the operation of the above embodiment will be described with reference to Fig.2 and Fig.3 showing the processing algorithm of the controller 5.

0030The TV camera unit 6 detects an image A (Fig.2) in front of the wiper 2, converts it into digital data at the A/D converter 61 included therein, and continuously delivers the data to the image memory 71 of the image storage 7 as well as the change-over switch 8. At this time, storing the image data from the TV camera unit 6, the image memory 71 is updated by the latest image data.

0031In this state, the data of the image memory 71 has not yet been transferred to the output image memory 72.

0032In the meantime, the wiper 2 is being driven by the wiper motor 3 the drive angle β of which is detected by the angle sensor 4 and is read to the controller 5, as shown at Step S1 in Fig.3.

0033The controller 5 then determines whether or not the drive angle β resides within a predetermined image pickup angle range β₁ ∼ β₂ shown in Fig.2 of the TV camera unit 6, as shown at Step S2.

0034As a result of this determination, if it is found that the drive angle β of the wiper 2 resides in the angle range (β₀ &lt; β ≦ β₁ or β₂ &lt; β ≦ β₃) shown by oblique lines in Fig.2, which means that the detected image A is not disturbed by the wiper 2, the controller 5 makes the change-over switch 8 change over to the side of the TV camera unit 6 to provide as an output the detected image data, as shown at Step S3.

0035If it is found that the drive angle β of the wiper 2 resides in the angle range (β₁ &lt; β &lt; β₂) other than the oblique line portion in Fig.2, the detected image A is disturbed by the wiper 2 so that it can not be used as it is. It should be noted that the angle range β₁ ∼ β₂ can be preset in the controller 5 so as to correspond with the detected image A as a reference.

0036Therefore, the controller 5 makes the change-over switch 8 change over to the side of the image storage 7, as shown at Step S4.

0037Then, the controller 5 makes the update image data which is always updated and stored at the image memory 71 of the image storage 7 transfer to the output image memory 72 as shown at Step S5, and makes the data of the output image memory 72 provide as an output through the change-over switch 8 as shown at Step S6.

0038Thus, when the wiper 2 resides outside the angle ran ge β₁ ∼ β₂, the detected image A from the TV camera unit 6 is directly provided as dynamic image data output without change, and when the wiper 2 resides inside the pickup angle range β₁ ∼ β₂, the update image A' which has been stored while updated at the image memory 71 is sequentially transferred as a static image to the output image memory 72 for a time interval the wiper 2 takes to pass through the angle range β₁ ∼ β₂. Then, the static image data of the output image memory 72 is read out and provided as an output through the change-over switch 8.

0039Fig.4 is a block diagram illustrating the arrangement of another embodiment of an image detection system according to the present invention for the purpose of chasing an object in front of the car by using an image taken by the TV camera unit 6.

0040For this purpose, the TV camera unit 6 is mounted on a pan head 60 which serves as panning means for panning the TV camera unit 6 in the up/down and right/left directions and provides as an output an angle signal in the respective directions at the time of panning. So, the controller 5 serving as change-over controlling means generates a control signal for the image storage 7 and the change-over switch 8 by comparing a predetermined image pickup angle range as shown in Fig.2 of the TV camera unit 6 corrected with the pan angle provided from the pan head 60 with the angle of the wiper 2 detected by the angle sensor 4. It is to be noted that a control signal shown by dotted line in Fig. 4 is provided for the pan head 60 when a control unit (not shown) finds it necessary to pan the TV camera unit 6 as a result of processing image data from the change-over switch 8, and that other elements correspond with the elements shown by the same reference numerals in Fig.1.

0041Next, the operation of the above embodiment in Fig.4 will be described with reference to Fig.2 and Figs.5 to 7.

0042It is now assumed that the TV camera unit 6 supported by the pan head 60 can pan to the maximum angle ± α₁ in the up/down pickup directions and the maximum angle ± ϑ₁ in the right/left pickup directions with reference to the origin 0 as shown in Fig.5. Namely, a pickup image A, shown by oblique lines, corresponding to the detected dynamic image A in Fig.2 can move within an area shown by dotted line.

0043At this time, the pan head 60 always provides as an output for the controller 5, by means of a potentiometer or a rotary encoder included therein, the angles of α (α ≦ α₁) and ϑ (ϑ ≦ ϑ₁) respectively in the up/down and right/left directions at the the time of panning. It is to be noted that such an angle detection may be carried out by various known techniques.

0044The TV camera unit 6 on the pan head 60 takes an image A (see Fig.2) in front of the wiper 2, converts it into digital data at the A/D converter 61, and continuously delivers the data to the image memory 71 of the image storage 7 and the change-over switch 8.

0045At this time, storing the image data from the TV camera unit 6, the image storage 71 is continuously updated by the latest image data. In this state, the data of the image memory 71 has not yet been transferred to the output image memory 72.

0046In the meantime, the wiper 2 is being driven by the wiper motor 3 the drive angle β of which is detected by the angle sensor 4 and is provided for the controller 5, shown at Step S11 in the flow chart of the controller 5 in Fig.7.

0047Also, the controller 5 is given with an up/down angle α and a right/left angle ϑ which are the pan angles of the TV camera unit 6, as shown at Step S12.

0048From these angles, the controller 5 recognizes the pickup direction of the TV camera unit 6 and correspondingly converts the predetermined angle range β ₁ ∼ β₂ of the detected dynamic image A shown by oblique lines in Fig.5 into an angle γ₁ commencing the interference with the wiper 2 and an angle γ₂, terminating the interference of the pickup area A as shown in Fig.6, as follows at Step S13:

0049At first, assuming that a distance from the panning axis 60a of the pan head 60 to the cleaning face of the wiper be δ, the size of the pickup area A be L₁ long by L₂ wide, and a distance between the rotating axsis of the wiper 2 and the origin 0 of the pickup area A be H, the angles γ₁, γ₂ are given by the following equation:<maths id="math0001" num=""><img file="EP0477986A2_D0001.tif" /></maths>

0050Therefore, according to the up/down angle α and the right/left angle ϑ of the pan angle, pickup angles k₁, k₂ are corrected from the reference angle range β₁ ∼ β₂ (see Fig.2) as follows: <maths id="math0002" num=""><math display="inline"><mrow><mtext>k₁=90°-γ₁</mtext></mrow></math><img file="EP0477986A2_D0002.tif" /></maths><maths id="math0003" num=""><math display="inline"><mrow><mtext>k₂=90°+γ₂</mtext></mrow></math><img file="EP0477986A2_D0003.tif" /></maths>

0051Namely, in the angle range k₁ ∼k₂, the wiper image gets into the pickup area.

0052It is to be noted that the size L₁, L₂ of the pickup area A can be predetermined by the aforementioned distance δ and the pickup angle of the TV camera unit 6.

0053The controller 5 which has thus calculated the corrected angle range k₁ ∼k₂ determines whether or not the drive angle β from the angle sensor 4 resides within the corrected angle range k₁∼k₂ of the TV camera unit 6, as shown at Step S14.

0054As a result of this determination, if the drive angle β of the wiper 2 resides in the angle range (β ≦ k₁ or k₂ ≦ β) shown by oblique lines in Fig.6, which means that the detected dynamic image A is not disturbed by the wiper 2, the controller 5 makes the change-over switch 8 change over to the side of the TV camera unit 6 to provide as an output the detected image data without changes, as shown at Step S15.

0055On the other hand, if the drive angle β of the wiper 2 resides in the angle range (k₁ &lt; β &lt; k₂) within the oblique line portion in Fig.6, the detected image A is disturbed by the wiper 2 so that it can not be used as it is.

0056Therefore, the controller 5 makes the change-over switch 8 change over to the side of the image storage 7, as shown at Step S16.

0057Then, the controller 5 makes the update image data which is always updated and stored at the image memory 71 of the image storage 7 transfer to the output image memory 72, as shown at Step S17, and makes the data of the static image A' of the output image memory 72 provide as an output through the change-over switch 8, as shown at Step S18.

0058Thus, when the wiper 2 resides outside the predetermined image pickup angle range k₁∼k₂ corrected according to the pan angle of the TV camera unit 6, the detected dynamic image A is directly provided as a dynamic image data output without changes. However, when the wiper 2 resides within the pickup angle range k₁∼k₂, the update static image A' which has been stored while updated at the image memory 71 is sequentially transferred as static image data to the output image memory 72 for a time interval the wiper 2 takes to pass through the pickup angle k₁∼k₂. Then, the data of the output image memory 72 are read out therefrom and provided as outputs through the change-over switch 8.

0059Fig.8 is a block diagram illustrating the arrangement of a further embodiment of an image detection system according to the present invention for the purpose of substituting predetermined data for the image of the wiper during moving.

0060For this purpose, an image processing circuit 50 is connected to the TV camera unit 6 and the angle sensor 4 and serves as image processing means which determines the range of scanning lines to be mashed with an angle signal from the angle sensor 4 and masks the portion of scanning lines in the masked range with respect to an image signal obtained from the TV camera unit 6.

0061The image processing circuit 50 is formed of a horizontal synchronizing detection circuit 51 for detecting a horizontal synchronizing signal in the image signal from the TV camera unit 6, a scanning line counter 52 for counting the scanning line number of the detected image signal based on the horizontal synchronizing signal detected at the horizontal synchronizing detection circuit 51, an A/D converter 53 for converting pixel signals into the corresponding digital signals between adjacent scanning lines, a buffer memory 54 for storing the output data from the A/D converter 53, and CPU 55 responsive to the scanning line number from the counter 52 and the wiper angle ϑ from the angle sensor 4 to control the A/D converter 53 and the buffer memory 54. It is to be noted that other elements correspond with the elements shown by the same reference numerals in Figs.1 and 4.

0062Next, the operation of the above embodiment in Fig.8 will be described with reference to Figs.9-11.

0063The TV camera unit 6 detects an image A of an object (see Fig.8) in front of the wiper 2 and continuously delivers the image signal to the image processing circuit 50, as shown at Step S21 in the flow chart of the image processing circuit 50 in Fig.11.

0064On the other hand, the wiper 2 is being electrically driven by the wiper motor 3, and a signal indicating a drive angle ϑ of the wiper motor 3 is detected by the angle sensor 4 interlocked with the wiper motor 3 and is then provided for the image processing circuit 50, as shown at Step S22.

0065It is to be noted that the position of the camera is preset such that the direction of scanning lines of the TV camera unit 6 be perpendicular to the direction of the moving (cleaning) of the wiper 2, as shown by oblique lines in Fig.9.

0066Then, the image of the wiper 2 during the cleaning operation is detected by the TV camera unit 6. If the wiper image is positioned at such a position as shown by oblique lines in Fig.9 and it is assumed that the number of invalid scanning lines which the image of the wiper crosses and forms an image signal be n, the CPU 65 of the image processing circuit 50 calculates scanning line numbers j+1 and j+n in the scanning line range on the basis of the drive angle ϑ of the wiper 2 detected by the angle sensor 4, as shown at Step S23. It is to be noted that the drive angle at the time when the wiper 2 passes through the image pickup area A shown by a dot-dash line in Fig.9 is predetermined from the mutual positional relationship of the wiper 2 and the TV camera unit 6 so that where in the image taken by the TV camera unit 6 the image of the wiper 2 intrudes into is to be found from the drive angle ϑ from the angle sensor 4.

0067Hereinafter, the method of calculating the above-noted scanning line numbers j+1 and j+n from the drive angle of the wiper 2 will be described with reference to Fig.10.

0068In Fig.10, assuming that the size of the pickup area be L₁ long and L₂ wide and the distance between the rotational center of the wiper 2 and the origin 0 of the pickup area A be H, and the horizontal distances ℓ₁. ℓ₂ from the origin 0 in the range of the scanning lines j+1∼j+n (shown by oblique lines) which are thought to be crossing the wiper 2 are given by the repective equations: <maths id="math0004" num=""><math display="inline"><mrow><mtext>ℓ₁ = {H - (L₁/2)} tan ϑ</mtext></mrow></math><img file="EP0477986A2_D0004.tif" /></maths><maths id="math0005" num=""><math display="inline"><mrow><mtext>ℓ₂ = {H + (L₁/2)} tan ϑ</mtext></mrow></math><img file="EP0477986A2_D0005.tif" /></maths>

0069Namely, if the wide distance L₂ of the pickup area is formed by N scanning lines, the position of the scanning lines of the image of the wiper 2 resides between the distances ℓ₁ and ℓ₂.

0070Accordingly, the scanning line numbers j+1 and j+n corresponding to the distance range ℓ₁ ∼ ℓ₂ are given by the following equations because L₂ corresponds to N, ℓ₁ corresponds to j+1, and ℓ₂ corresponds to j+n, respectively: <maths id="math0006" num=""><math display="inline"><mrow><mtext>j + 1 = N {(1/2) - (ℓ₁/L₂)}</mtext></mrow></math><img file="EP0477986A2_D0006.tif" /></maths><maths id="math0007" num=""><math display="inline"><mrow><mtext>j + n = N {(1/2) - (ℓ₂/L₂)}</mtext></mrow></math><img file="EP0477986A2_D0007.tif" /></maths>

0071It is to be noted that in practice a margin may be given to the above j+1 and j+n, taking into account that the wiper 2 has an arm or blade as can be unintentionally moved due to its transformation.

0072Then, the following masking operation will be carried out with respect to the j+1_st scanning line∼ j+n_th scanning line to be masked as noted-above among all of the scanning lines forming the image signal provided as an output from the TV camera unit 6:    First of all, the horizontal synchronizing detection circuit 51 of the image processing circuit 50 detects a horizontal synchronizing signal from the detected image signal of the TV camera unit 6, as shown at Step S24.

0073Then, the scanning line counter 62 counts the scanning lines from the number of 1 to the maximum N included in the horizontal sysnchronizing signal as detected and the count is provided for the CPU 65, which carries out the following processing in the respective cases of the count a being such that j+1 ≦a ≦j+n, a&lt;j+1, or j+n &lt;a, as shown at Step S25.

0074At first, in the case where the count a is such that j+1≦ a ≦j+n, a row of blank data corresponding to the pixels of the scanning line is stored at the buffer memory 64, as shown at Step S26. It is to be noted that the blank data may be "1" if "0" data are detected for actual wiper images. Other various blank data may also be used if predetermined.

0075In the case where the count a is such that a&lt;j+1 or j+n&lt;a, the CPU 65 makes the A/D converter 63 convert the pixel signals into the corresponding digital data in the scanning lines, as shown at Step S27 and stores the data row into the buffer memory 64 in correspondence with the scanning lines, as shown at Step S28.

0076The CPU 65 sequentially reads the data row for each scanning line out of the buffer memory 64, as shown at Step S29, and provides as image data output for one screen after the masking operation, while the wiper portion gives no rise to processing error because of the blank data disregarded for the following data processing.

0077It is to be noted that the scanning lines forming the image shown in Fig.9 are formed of 525 scanning lines (=N scanning lines) according to the NTSC system. In this case, the range of the scanning lines 1∼j+1 and j+n ∼525 is provided as valid image region where no image of the wiper 2 is included.

0078Next, the method of the present invention wherein instead of the scanning line portion as masked in the above masking operation being given blank data, this portion is substituted by data before masked will be described. It is to be noted that the flow of the processing of this alternative is shown by dotted lines.

0079The CPU 65 makes each of the pixel data row for each of the scanning lines after the A/D conversion which have been stored as data in the buffer memory 64 store in the frame memory 66 for one frame of the screen in the case where the count a is such that a&lt;j+1 or j+n&lt; a, as shown at Step S30. Namely, the pixel data for each of the scanning lines stored in the frame memory 66 are update non-masked data.

0080Therefore, the CPU 65 reads the pixel data row of the scanning lines corresponding to the count of the scanning line counter 62 out of the frame memory 66 in the case where the count a is such that j+1 ≦ a ≦ j+n, as shown at Step S31.

0081Then, the pixel data row as read out is again stored in the buffer memory 64, as shown at Step S32.

0082Thereafter, the data of the buffer memory 64 are provided as outputs as aforementioned, as shown at Step S29, thereby transplanting the data just before masked into the scanning line portion to be masked.

0083Thus, the image of the wiper 2 intruding into the detected image is masked and blank-displayed, or substituted by image data just before masked, whereby a portion displaying no wiper, i.e. non-masked portion is provided as an output data out of the buffer memory 64 because of being valid.

0084While a number of alternatives and modifications have been discussed above, it will be appreciated that the invention encompasses all forms and variations within the scope of the appended claims.