MXPA00011809A - Imaging system for vehicle headlamp control - Google Patents

Abstract

An imaging system for use in a vehicle headlamp control system includes an aperture, an image sensor, a red lens blocking red complement light between the aperture and the image sensor, and a red complement lens blocking red light between the aperture and the image sensor. Each lens focuses light onto a different subwindow of the image sensor. The imaging system allows processing and control logic to detect the presence of headlamps on oncoming vehicles and tail lights on vehicles approached from the rear for the purposeof controlling headlamps. A light sampling lens may be used to redirect light rays from an arc spanning above the vehicle to in front of the veicle into substantially horizontal rays. The light sampling lens is imaged by the image sensor to produce an indication of light intensity at various elevations. The processing and control logic uses the light intensity to determine whether headlamps should be turned on or off. A shutter may be used to protect elements of the imaging system from excessive light exposure.

Description

: IMAGE FORMATION SYSTEM FOR THE CONTROL OF THE FRONT LIGHTHOUSE OF A VEHICLE Technical Field The present invention relates to imaging systems for use in a control system such as a vehicle headlight control.

Background Art The headlights illuminate a region in front of a vehicle which allows a driver to observe the region when the ambient light is insufficient. The headlights also allow the vehicle to be observed by pedestrians and drivers; other vehicles. The high beam headlamps provide even greater illumination and have a greater coverage region. However, high beam headlamps could dazzle drivers in vehicles in the opposite direction and drivers in vehicles crossing in the same direction within the region of high beam coverage. Traditionally, a driver has had to manually control the ignition and shutdown of REF: 125112 headlights and the change between high beam and low beam.

One difficulty with manual control is that the driver may forget to turn on the headlights at dusk making the vehicle difficult to observe. Another difficulty is that the driver may neglect to reduce the intensity of the headlights of high light beam for traffic in the opposite direction or when approaching another vehicle from the rear.

Previous attempts to automatically control the operation of the vehicle's headlights have used detectors that provide a simple output or a very small number of output signals to the associated control system. For example, a simple output detector has been used to detect ambient light to determine when to turn the headlights on or off. Also, a simple output detector has been used to determine when to decrease the intensity of the car's headlight. While the on / off control of the headlight using a single detector input has achieved limited success in automotive applications, dimmer control of the headlight light intensity is currently not offered due to its many drawbacks.

The arrangement of the imaging detectors and various scanning techniques have been proposed, but even with the reduced costs made possible by current electronic chickens, these detectors and technique have not produced the on / off control functions and the decrease in the intensity of the headlight's light. Such detection systems typically have hundreds of rows and columns of pixel detectors that generate hundreds of thousands or even millions of pixels. At a typical video speed of 30 cycles per second, this requires conversion and data processing speeds in millions of operations per second.

The on / off control of the headlight can be based on the levels of ambient light. The control of the headlight light detector can be based on the recognition of the headlights of the vehicles of the opposite direction and the rear headlights of vehicles near the rear. Since the resolution required to detect the levels of ambient light and to detect the lights of the headlights and rear lights is lower than that required for traditional images. A smaller image formation arrangement could be used, and for this, slower processing electronics.

To distinguish the red tail lights from the other lights, the image formation system must produce readings in at least two different color bands. The first of the two methods usually used to detect colors with an image detector has been to cover a third of the pixel detection scenes in the image with a red or red attenuation filter, one third of the pixels with a blue or blue attenuation filter and one third of the pixels with a green filter or green filter. This is often done, for example, by placing the alternating red, green and blue bands on columns of pixels. Each pixel site registers a color and interpellation is used to supply the two missing colors in each pixel scene.

When coupled with a low resolution imager, this technique for detecting color creates a problem. Due to the optics used, the projected image of a headlight or backlight observed by the image detection arrangement is very small, probably smaller than the resolution power of the lens. This projected image will be referred to as a point. When the spacing of the pixel is significantly smaller than the size of the point projected by the lens, a portion of a point of a particular color could not always collide with a detector scene of such a color. As the optical coverage pixel size or area per pixel is increased due to a corresponding reduction in the number of pixels, the gaps between similar colored pixel scenes become larger, unless a complicated interdigitated pixel pattern is used . Even if the reading of a particular color is not completely lost, having the total point image projected onto a pixel of another particular color or colors, the reading will be approximated depending on which portion of the point a pixel hits. Since the distinction of a color is usually a matter of determining the balance between two or more color components and not only of determining the presence or absence of a particular color component, when the small point of light in the projected image of a Headlight or tail light falls more on a pixel of one color than another, therefore, the measured balance is altered.

An additional disadvantage with this method results from the dyes used to implement the color filters. The dyes are normally organic and are subject to the degradation of thermal and light exposure. Since the dye remains directly on the individual pixel sites, the energy of a strong light source, such as the sun, is focused by the lens system directly on the dye.

A still further problem with this method is that it is expensive to have the color filter colorant applied and precisely recorded with the scene of the pixel detector in the image detector. The cost of adding the color filters directly on the pixel detector could be as expensive as the silicon image detection microcircuit itself.

A second method for the color of the image formation separates the light of the image into the red, green and blue components that are projected in separate image detectors each of which measures its filtered image of respective color. This requires a complicated optical array and three separate image detectors. The color separation technique often uses mirrors that selectively reflect a color and transmit the complementary color. These optical arrays typically require widely separate non-planar image detector scenes, making them difficult if not impractical to place these three detectors on a common silicone substrate or even in a common package. This technique presents a problem of three aspects. A simple detector array can not be used. A simple silicon microcircuit can not be used and a simple package can not be used.

What is needed is a cost-effective imaging system to be used in, for example, a headlight control system. To limit costs and complexity in the optics, the detector array, the processor and the processor interface should be used, a minimum number of pixels, preferably in a range that would be considered too small for the presentation of the satisfactory pictorial image. The imaging system should not use the spectral filtering that would place the dyes or color selection materials at the focal point of the lens system. The imaging system should supply the appropriate signals to determine the headlight attenuation control, the headlight on / off control, or both. The imaging system should also be protected against excessive light or thermal damage.

Brief Description of the Invention It is an object of the present invention to provide images for use in a headlight control system.

Another aspect of the present invention is to provide sub-windows in an image array - to detect the different color components of the scene.

Still another object of the present invention is to provide an optical system that allows a low resolution image detector to be used in a headlight control system.

A further aspect of the present invention is to produce different color components of a scene using an optical system that does not place filters in the focal plane of the optical system.

A further aspect of the present invention is to detect the elevational light levels for use in determining whether a headlight should be on or off in a manner that uses an image detector.

Yet a further aspect of the present invention is to protect the elements of a headlamp control image formation system from excessive light and heat.

Carrying out the above objects and other objects and features of the present invention, an image forming system is provided for use in a vehicle headlight control system. The image formation system includes a housing defining an aperture, the aperture generally opening towards a scene, an image detector within the opposite housing from the aperture, a first lens for focusing the light of the scene onto a first portion. of the image detector and a second lens for focusing the light from the scene on a second portion of the image detector, the second portion of the image detector is separated from the first portion.

In one embodiment, the first lens focuses light at a first wavelength in the image detector and the second lens focuses light at a second wavelength in the image detector. In a refinement, the focal length of the first lens at the first wavelength is substantially the same as the focal length of the second lens at the second wavelength. In a preferred embodiment, the first lens attenuates the light substantially cyan in color and the second lens substantially attenuates the red light in color.

In another embodiment, the image detector has a low resolution.

In yet another embodiment, a baffle extends from an area between the first lens and the second lens to the image detector. The baffle reduces the light passing through the first lens that collides with the second portion of the image detector and reduces the light that passes through the second lens that strikes the first portion of the image detector.

In a further embodiment, the image sensing system includes a shutter to reduce the intensity of light entering the aperture. In a preferred embodiment, the shutter is an electrochromic window.

In a further embodiment, a maximum focal length is the largest of the focal length of the first lens and the focal length of the second lens. The housing defines the opening at least twice the maximum focal length away from the first lens and the second lens. In a still further embodiment, a first portion of the housing defining the opening is positioned to block light that would otherwise travel through the first lens and would strike as scattered light in the second portion of the image detector, and a second portion of the The housing defining the opening is positioned to block light, which would otherwise travel through the second lens and would strike as scattered light in the first portion of the image detector.

An image detection system is also provided, which includes a housing defining an opening that opens, in general, toward a scene in the front of a vehicle, an image detector located within the housing and a light separation lens. placed in the opening. The light separation lens assembles the light rays from a region defined by a vertical arc extending from substantially above the aperture to substantially the front of the aperture and redirects the assembled light rays to the image detector. The lens could gather the light rays from a narrow horizontal arc in front of the aperture.

In one embodiment, the light separation lens is further operated to gather the light rays of the separated elevating regions and to redirect the assembled light rays of each elevationally separated region to a different group of pixel detectors in the image detector, allowing the image detector to detect the light level at different angular elevations. The vacated regions could be separated by 10 degrees of elevation.

In another embodiment, the system includes a first sub-window of pixel detectors, a second sub-window of pixel detectors, a red lens within the housing between the light separation lens and the image detector, to substantially project the red components of the redirected light rays in the first sub-window, and a red attenuation lens within the housing between the light separation lens and the image detector, the red attenuation lens to substantially project the components of red attenuation of redirected light rays in the second sub-window.

A system for controlling at least one headlamp includes a headlamp driver operated to turn the headlamps on or off based on a received on / off control signal, an image detector comprised of a array of pixel detectors, a system lens operated to gather the light rays from a region defined by a vertical arc extending from substantially above the vehicle to substantially the front of the vehicle and redirecting the assembled light rays to the image detector, and a processing system and operated control to read the light levels of the pixel detectors and determine the on / off control signal based on the comparison of light levels to a threshold.

In one embodiment, the processing and control system can determine the threshold based on the color components projected onto the first and second sub-vents. Alternatively, the processing and control system can determine whether the region defined by the vertical arc forms a blue sky image or a cloudy sky and use a lower threshold for the blue sky than for the cloudy sky.

In another embodiment, the processing and control system can determine the on / off control signal based on the comparison of light levels to a hysteretic threshold.

In yet another embodiment, the processing and control system can determine the on / off control signal based on a time delay of a previous change in the on / off control signal.

The foregoing objects and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best ways of carrying out the invention when taken in connection with the accompanying drawings.

Brief Description of the Drawings FIG. 1 is a headlight control system that could be used as an image forming system according to the present invention; FIG. 2 is a schematic diagram of an image detector according to the present invention; FIG. 3 is an optical system according to the present invention; FIG. 4 is an elongated portion of the optical system shown in FIG. 3; FIG. 5 is an alternative embodiment of an image forming system that includes a baffle according to the present invention; FIG. 6 is a schematic diagram illustrating the operation of two lenses for one embodiment of the present invention; FIG. 7 is a lens for use in an embodiment of the present invention for the control of on / off of the headlight; Y FIG. 8 is an illustrative optical system incorporating the lens of FIG. 7 Best Ways to Carry Out the Invention With reference now to FIG. 1, a block diagram of a system embodying the present invention is shown. The control system of the headlight 20 is used in a vehicle to control one or more headlights 22. Control operations could include automatically switching the headlight 22 off and on automatically and automatically switching between the high beam and the low beam for the headlight 22.

Scene 24 is generally on the front of a vehicle. The light rays 26 of the scene 24 enter the image forming system 28 by first passing through the optical system 30. The focused rays 32 of the optical system 30 collide with the image detector 34 in the focal plane of the optical system 30. The processing and control system 36 receives the output of the image detector 38 and produces the control of the image detector 40. The processing and control system 36 also generates the control signal of the automatic headlight 42 which is received by the driver of the vehicle. headlight 44.

The processing and control system 36 could carry out continuous cycles to check for the presence of headlights and taillights in scene 24. During each cycle, two images of the image detector 34 are acquired. As will be described in greater detail below, an image has predominantly red components and an image has predominantly red attenuation components. The brightness of the bright spot in the red image could indicate the presence of backlights in scene 24. Brightness of the bright spot in both red and reddish images could indicate the presence of headlights in scene 24. Counters could be used to indicate the number of successive scenes, for which a bright point brightness has been detected in approximately the same location. Once the count reaches a threshold value, -the luminous point is assumed to be from another vehicle and an approximate action is taken, such as attenuation of the light of the headlight 22. The above description is a simplification of the described modalities in the main application mentioned above serial number 08 / 831,232.

The headlight controller 44 generates the signal from the headlight controller 46 which is received by the headlight 22 which causes the headlight 22 to turn off or on or switch between the high light beam and the low light beam. The headlight 22 could produce the illumination of the headlight 48, which illuminates a portion of the scene 24. The headlight controller 44 could also receive the manual on / off signal 50 of the manual on / off control 52 and the signal of the manual light reducer 54 of the manual light reducer control 56. The manual on / off control 52 and the manual light reducer control 56 allow the driver to manually control the operation of the headlights 22. In an alternative mode , - '»l'S. -Jf-, - »- 'one or both of the on / off signals 50 of the headlight and the signal of the manual dimmer 54 could also be used for the control and processing system 36 to determine the status of the headlight 22.

In an alternative embodiment, the baffle 58 is placed before the image forming system 28. The baffle 58 then receives the light rays 26 from the scene 24 and removes the attenuated light rays 60 to the optical system 30. The baffle 58 reduces or it eliminates the amount of light reached by the image detector 34 when the light of scene 24 is excessive, such as, for example, at dawn or dusk when the sun is close to the horizon. The baffle 58 could be implemented using a mechanical means, such as screens, an iris or the like, under the control of the processing and control system 36 as provided by the control signal of the baffle 62. Alternatively, the baffle 58 could be a glass or photosensitive plastic. In a further alternative, the baffle 58 could be a clock window as described in U.S. Pat. 4,902,108 entitled "Single-Compartment, Self-Erasing, Solut ion-Phase Elect Rochromic Devices, Solutions For Use Therein, And Uses Thereof" by H.J. Byker that is incorporated here by reference.

The image detector 34 should include a minimum number of detection elements to reduce the processing requirements and decrease the cost. To efficiently use the image detector 34 with a relatively small number of pixel detectors, the projected image of a distant rear light or headlight in scene 24 should be comparable in size or smaller than a single pixel in the image detector 34. The relative intensities of the color components calculated from the data processing of the image of such projected image, they should be in general, independent of the specific position of the projected image in the array. Therefore, it is desirable to simultaneously project the differently filtered images of scene 24 into spatially separated scenes, preferably within the same pixel array or alternatively in separate pixel arrays. One or more pixel arrays are preferably on the same substrate and in the same package.

A preferred arrangement is to project the separate scenes into a common array large enough to include the scenes are separate sub-windows, and to use the common control logic that provides a means to simultaneously expose and process the multiple scenes. A control of this type is described in the co-pending patent application "Control Circuit for Image Array Sensors" with serial number 08 / 933,210 which is incorporated herein by reference. The descriptions of the image array and the lens systems are provided with respect to FIGS. 2 to 8 later.

In a preferred embodiment, when a small area light source is detected, the scene is analyzed to determine the simple or small group of pixels that have illumination levels substantially higher than the background level of the surrounding pixels. The light reading is integrated or added to this group of pixels with an optional subtraction of the average background level. This process is repeated for the scene corresponding to each color component. In this way, the readings are relatively independent of whether the illumination is contained in the pixel detector or whether the illumination collides a pixel boundary and the light distribution portions on two or more junction pixel detectors. This technique increases the tolerance for a small registration error between the sub-windows for different color components when comparing the ratio of quotients of the various color components of a given small area light source.

With reference now to FIG. 2, a schematic diagram representing an image detector according to the present invention is shown. The image detector 34 includes an array of pixel detectors, one of which is indicated by 70, arranged in rows and columns. In an exemplary embodiment, the image detector 34 includes 80 rows per 64 columns of pixel detectors, most of which are not shown for clarity. The image detector 34 includes the upper edge 72, the lower edge 74, the left edge 76 and the right edge 78 that define a region covered by the pixel detectors 70. The use of directionality, such as, for example, superior, Lower, left and right is provided for ease of explanation and is not intended to limit the present invention to a particular orientation.

The image detector 34 is divided into several sub-windows. In one embodiment, two sub-windows are used to form the image of scene 24 into two color components. The upper sub-window 94 is surrounded by the lines 78, 80, 82 and 84, and contains the pixel detectors 70 that bombard an image projected through a lens that is colored to pass the red light. The lower sub-window 96 is surrounded by the lines 78, 86, 82 and 88 and includes the pixel detectors 70 on which an image is projected through a lens that is colored to pass the cyan or red attenuation light.

The lenses provide a field of view of scene 24, such as, for example, width of 22 ° by height of 9 °. A space between the line 80 and the upper edge 72 and between the lines 84 and 90 allows an elevation adjustment to correct the misalignment of the image forming system 28 in the vehicle. To make the adjustment, the boundaries of the upper sub-window 94, represented by the line 80 and the line 84 respectively, move up or down within the range between the upper edge 72 and the line 90. Similarly, the lines 86 and 88 represent the limits for the lower sub-window 96 that could be moved between the lower edge 74 and the line 92. In the exemplary embodiment, an elevation adjustment is allowed through a range of approximately 4.8 °. Sub-windows 94 and 96 normally move up or down together, but the origin of one relative to the other is also adjustable to compensate for variations in the registration of one sub-window with respect to the other.

The pixel detectors 70 falling within the region bounded by the lines 90 and 92 could receive the light from the red and attenuation red lenses. Therefore, this region is not normally used as part of the area of active image formation. The pixel detectors 70 in this region could be removed to make room for other circuits, but because of the relatively small percentage of area loss and the flexibility to use the full 64x80 pixel array in other applications, it might be more beneficial to leave the pixel detectors 70 in the region bounded by lines 90 and 92. Also, it is not convenient to interrupt the signal paths along the columns in the array. In the exemplary embodiment, less than 8.5% of pixel detector 70 falls between lines 90 and 92. A mode that limits the required width between lines 90 and 92 is described with respect to FIG. 5 later. Red and red attenuation lenses are described with reference to FIGS. 3 to 6 and FIG. 8 later.

In one embodiment of the present invention, the pixel detectors 70 falling between the left edge 76 and the line 82 are used to control the on / off of the headlight. This use is described with respect to FIG. 8 later.

In another embodiment of the present invention, the image detector 34 is divided into more than two sub-windows for the image forming scene 24 into a plurality of color components. For example, the upper sub-window 94 and the lower sub-window 96 could each be separated into two sub-windows, creating four sub-windows. Multiple sub-windows could be arranged in a two-by-two mesh or one-by-one mesh. The spacing between the sub-windows allows vertical and horizontal adjustment.

The pixel detectors 70 in the image detector 34 could be charge coupled devices, photodiodes or the like. In a preferred embodiment, the pixel detectors 70 are pixel detectors , < ^ aa 'r ~? ** u? ßiUi3? j¡ < £: * CMOS assets. An APS image detector is described in a co-pending patent application entitled "Wide; Dynamic Range Optical Sensor" with serial number: 09/002400 which is incorporated herein by reference.

Referring now to FIG. 3, an illustrative embodiment of the present invention is shown. The image forming system 28 includes the housing 100 with the opening 102 opening to the scene 24. The image detector 34 is located within the housing 100 opposite the opening 102. The support 104 is located within the housing 100 and maintains the red lens 106 and the red attenuation lens 108 between the image detector 34 and the aperture 102. The holder 104 also prevents light from entering through the aperture 102 from colliding with the image detector 34, unless The light passes through the red lens 106 or the red attenuation lens 108. The range of the pixel detector 70 is used to form the upper sub-window 94, ie the upper edge 72 and the line 90, as well as for forming the lower sub-window 96, that is the lower edge 74 and the line 92, are indicated in the image detector 34.

Preferably, the opening 102 locates several focal lengths of the lenses 106, 108 on the front of the lenses 106, 108. The aperture 102 is characterized by minimizing the distance between the boundaries of two images separately projected onto the image detector 34, reducing the amount of crosstalk between the upper sub-window 94 and the lower sub-window 96. This is done using an edge of the aperture 102, which is placed to block light that would otherwise travel through the lens 108 and would crash as diffusion light in the upper sub-window 94. Likewise, another edge of the aperture 102 is placed to block light that would otherwise travel through the lens 106 and would crash as diffusion light in the lower sub-window 95 The use of aperture 102 to limit optical crosstalk is described with respect to FIG. 4 later. A further improvement is to incorporate a baffle placed between the lens systems 106, 108 and extending to the image detector 34 to further reduce the required distance between the upper sub-window 94 and the lower sub-window 96 to adequately minimize optical crosstalk. The use of a baffle is described with respect to FIG. 5 later. As a further extension, an optical light collection system is placed in a portion of the aperture 102, so that a used image is projected in a third region of the image detector 34, while maintaining the proper optical separation between the three images. The optical light collection system and its application is described in FIGS. 7 and 8 later. The red lens 106 and the red attenuation lens 108 are conceptually shown. One embodiment of the additional shape and operator of the red lens 106 and the red attenuation lens 108 are described with respect to FIG. 6 later.

In one embodiment of the present invention, the optical system 30 includes more than two lens systems 106, 108 for projecting a plurality of color filtered images of the scene 24 into the image detector 34. For example, four lenses can be arranged in a two-by-two arrangement of the lenses. Three of the lenses could pass light in a band of different color, such as red, green and blue for real color image formation. The fourth lens could substantially pass unfiltered light for low light level image formation.

With reference now to FIGS. 3 and 4, the operation of the imaging system will now be described.

The lower point 110 represents a distant point in the scene 24 which is projected as the point 112 in the image detector 34. The lower point 110 is in the lower degree of the field of view and is projected onto the point 112 in the upper degree of the lower sub-window 96 as indicated by the line 92 of the unobstructed portion of the image projected by a red attenuation lens 108. Since the lower point 110 is a distance of typically 50 to 200 meters of the headlights of vehicles in the opposite direction and the rear taillights of vehicles approaching backward, when most of the actions of the headlight controller start, the light rays 26 indicated by the lower light beam 114, the lightning of the upper light 116, and the central light beam 118 are almost parallel before colliding with the red attenuation lens 108. The red attenuation lens 108 focuses the lower beam 114, the upper beam 116 and the beam ntral 118 at the point 112 on the image detector 34. The lower aperture edge 120 of the aperture 102 is positioned so that the lower ray 114 only clarifies the lower aperture edge 120 and the lower edge of the attenuation lens red 108 indicated by 122. With this arrangement, the aperture 102 is not only large enough to block the light of the lower point 110, which would otherwise fall on the red attenuation lens 108 which focuses on the point 112.

The beam 124 is the most directed upward ray which will clarify the lower opening edge 120 and pass through the red attenuation lens 108. ared to the beam 114, the beam 124 traverses a route that is angled upwards by an amount which increases, so that it is greater by a lens diameter than the beam 114 when it enters the red attenuation lens 108 in the upper part of the lens 108 indicated by 126. This angular deviation of the beam 124 of the parallel rays 114, 116 and 118 is approximately preserved as beam 124 leaves the red attenuation lens 108. Ray 124 strikes image detector 34 at the lower limit 90 of upper-side window 94 at a point indicated by 128.

In one embodiment, the red lens 106 and the red attenuation lens 108 have an F number of 4, are nominally 1 millimeter in diameter. The aperture 102 is 6 focal lengths of the red lens 106 and the red attenuation lens 108. The dimension B for the housing 100 is approximately 28 millimeters.

One of the advantages of miniaturization is that the aperture 102 can be spaced a reasonably large number of focal lengths of the red lens 106 and the red attenuation lens 108 without incurring an excessively large structure. The furthest opening 102 is of the lenses 106 and 108, the greater distance between the lines 90 and 92 can be reduced, so that the choice of spacing of the aperture 102 to the lens 106 and 108 is an impractical matter of the roll size against the loss of detection area.

For the illustrative embodiment described above, the beam 124 travels a sixth of the red attenuation lens 108 to the image detector 34 from the aperture 102 to the red attenuation lens 108. Therefore, the beam 124 strikes the detector of image 34 at a point that is about one sixth of the diameter of the attenuation lens of red 108 above point 112.

The high point 130 is in the upper degree of the field of view of scene 24. The projection of the high point 130 to the red attenuation lens 108 strikes the image detector 34 at a lower point of the region covered by the sub-window jtn? ü ^ ítfgt? am bottom 96. These rays are not represented because the projected image is not inside the sub-window 94 or 96.

Because the high point 130 is also distant from the opening 102, the upper beam 132, the lower beam 134 and the middle ray 136 are substantially parallel before hitting the red lens 106. The red lens 106 focuses the rays 132, 134 and 136 at the point 128 in the image detector 134 at the lower limit of the upper sub-window 94 marked by the line 90. As with the beam 124 described above, the beam 138 is the one that is directed further down the which can pass through the upper opening edge 140 and still be focused by the red lens 106, which collides with the image detector 34 at point 112. In this way, while the scattered light from the red attenuation lens 108 decreases to substantially zero when going from line 92 to line 90, the scattered light of red lens 106 decreases to substantially zero when going from line 90 to line 92.

With reference now to FIG. 5, an alternative embodiment of the present invention is shown. FIG. shows the same area of the image forming system 28 as seen in FIG. 4. The embodiment shown in FIG. 5 is the same as that shown in FIG. 4, with the exception of the addition of the deflector 142. The baffle 142 decreases: the region of the image detector 34 in which the lu: of the red lens 106 and the red attenuation lens 10E may collide.

As a simplified generalization, for a lens with infinite focus and aperture of diameter d, a diaphragm or baffle that is at the focal lengths n in front of the lens, can be placed to block the rays that would strike the focal plane at a distance of more than of d / n away from the portion of the image that is not affected by the diaphragm.

The baffle 142 extends substantially perpendicular to support 104 towards the image detector 34. Ideally, the baffle 142 would extend almost touching the image detector 34. However, the image detector 34 could include the cover glass of the gasket. detector 144 that could limit the extent of deflector 142.

Deflector 142 blocks beam 124 from the shock of L image detector 34. With deflector 142 in place, beam 146 represents the lowest ray that will clarify the lower aperture edge 120, passes through the red attenuation lens and collides with the image detector 34 at point 148. Point 148 is approximately two thirds of the distance from line 92 to line 90.

The beam 150 is the most directed beam that could be focused through the red attenuation lens 108 and on the image detector 34 in the absence of the lower aperture edge 120. The beam 150 strikes the image detector 34. at the point indicated by 152 in the area reserved for the red lens image 106.

There is little room for good optical treatment of the baffle 142 and the rays, such as 124 that collide with the baffle 142 at a low angle, will significantly reflect from the most obscured surfaces. The opening 102 in the front of the lenses 106 and 108 is performed much better than the baffle 142 in the exemplary embodiment shown, but the combination of the aperture 102 and the deflector 142 gives the best performance in minimizing the distance that it separates the upper sub-window 94 and the lower sub-window 96 to prevent a significant amount of light entering a lens 106 or 108 from falling on the sub-window projected by the other lens. Note that, instead of the spacing of sub-windows 94 and 96 and the distance between lines 90 and 92, this distance could be reduced by applying a deflector similar to baffle 142, but thinner, by reducing the spacing of the sub-frame. window, and re-centering the lenses 106 and 108 and re-dimensioning the aperture 102.

Referring now to FIG. 6, an exemplary embodiment of a pair of aspheric lenses is shown for use in the present invention. The drawing is provided to illustrate the operation of the lenses not to represent the precise shape or positioning of the lenses.

The red lens 106 has the front surface 200 facing the image detector 34 and the back surface 202 facing towards the image detector 34. At its furthest point, the front surface 200 is located at the C dimension of 4.25. millimeters of the image detector 34. The front surface 200 is an ellipsoid described by Equation 1: where Z is the value of the height of the lens surface along the optical axis as a function of the radial distance r of the optical axis, c is the curvature, k is the conical constant and the coefficients C2n are the polynomial coefficients of constant order. For the front surface 200, c equals 0.7194 and k equals -0.4529. The rear surface 202 is aspherical with a radius of 4.05 millimeters. The diameter of the attenuation lens of red 108, shown as dimension D, is 1.2 millimeters. The red attenuation lens 108 has a thickness, shown as dimension E, of 0.2 millimeters at its center. The focal length of the red lens is frequently dependent and is 4.25 millimeters for a wavelength of 680 nanometers.

The red attenuation lens 108 has the ^ ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^? tmm m É. front surface 204 facing far away from the image detector 34 and the rear surface 206 facing towards the image detector 34. At its furthest point, the front surface 204 locates the C dimension of 4.25 millimeters of the image detector 34. The front surface 204 is also an ellipsoid described by Equation 1 with the curvature c equal to 0.7059 and the conical constant k equal to -0.4444. The rear surface 206 is aspherical with a radius of 4.05 millimeters. The diameter of the attenuation lens of red 108, shown as dimension F, is 1.2 millimeters. The red attenuation lens 108 has a thickness, shown as dimension E, of 0.2 millimeters at its center. The focal length of the red attenuation lens 108 is frequency dependent and is 4.25 millimeters for a wavelength of 420 nanometers.

Referring again to FIG. 6, the effects of the frequency-dependent lengths in the lenses 106 and 108 are described. Due to the different aspheric face surfaces of the red lens 106 and the red attenuation lens 108, the red light rays 210 and the light rays 212 blue light are focused differently through each lens. The focal point of the red light rays 210 passing through the red lens 106 is on the surface of the image detector 34, while the blue light rays 212 passing through the red lens 106 focus a distance on the front. of the image detector 34. Also, the blue light rays 212 which pass through the red attenuation lens 108 are focused on the surface of the image detector 34 and the red light rays 210 passing through the attenuation lens. of red 108 focus a distance beyond the surface of the image detector 34.

In a preferred embodiment, the red lens 106 is made of a polymer that includes a dye to reduce the magnitude of the red attenuation light transmitted through the red lens 106. The red attenuation lens 108 is made of a polymer that includes a dye to reduce the magnitude of the red light transmitted through the red attenuation lens 108. As an alternative, at least one red lens surface 106 and the red attenuation lens 108 could be coated to achieve red filtering and the red attenuation filtering, respectively. A further alternative is to use separate filters between scene 24 and image detector 34. In particular, filters could be attached to support 104 either directly on the front or back of lenses 106 and 108.

In one embodiment of the present invention, more than two lenses 106, 108 are used. Each lens could be colored or dyed to accommodate a different color frequency. Preferably, each lens is formed so that the length of any lens 106, 108 at the pitch frequency of such a lens is the same as the focal length of any other lens 106, 108 at the pitch frequency of another lens.

Referring now to FIG. 7, a lens for use in an embodiment of the present invention for on / off control of the headlight is shown. The light separation lens 250 collects light from a range of directions, shown as the rays 251 to 260, from the horizontally forward direction to the vertically upward direction.

The inclinations of rays 251 to 260 were spaced in approximately 10 degree increments. The lens 250 redirects the rays in the opposite direction 251 to 260 to the output rays 261 to 270 along approximately the horizontal routes.

The approximately vertical beam 251 is refracted to the beam 271 on the front surface 272 of the lens 250. The beam 271 is internally reflected to the beam 273 on the surface 274 and the beam 273 is refracted to the beam 261. The surface 275 is approximately parallel to the beam 271 or is at an angle with the surface 274 slightly larger than the angle that would place the surface 275 parallel to the beam 271. If the surface 275 is at an angle with the smaller surface 274 of the angle that would place the surface 275 parallel to the beam 271, the beam 271 would be blocked when the ray 251 enters an upper point on the surface 272, whereby an unpleasant shadow is distributed over the surface 274 near the intersection of the beam 271 with the surface 275. The lens 250 tips the rays inlet 252 to 255 in a similar manner to produce the outlet rays 262 to 265. The surface 274 forms the underside and the surface 275 forms the upper side of a triangular shape with n a vertex pointing, in general, away from the front surface 272.

The beam 256 is refracted on the surface 280 to the beam 281 and the beam 281 is refracted to the beam 266 on the rear surface 282. Similarly, the beam 257 is refracted by the surface 283 to become the beam This method is refracted by the back surface 282 to become the beam 267. The surface 285 is approximately parallel to the beam 281 and the surface 286 is oriented to bisect approximately the angle between the beam 256 and the beam. 284. The lens 250 refracts the input rays 258 to 260 in a similar manner to produce the output rays 268 to 270. The surface 280 forms the underside and the surface; 285 forms the upper side of a triangular shape with a vertex pointing, generally, away from the rear surface 282.

In a preferred embodiment of the lens 250, the output rays 261 to 270 are progressively angled from slightly downwardly of the beam 261 to slightly upwardly of the beam 270.

In one embodiment, the lens 250 is formed of acrylic with a cross section as shown in FIG. 7. This mode will collect light in a 90 degree fan vertically oriented with a relatively small angle in the horizontal direction. In an alternative embodiment, the increased horizontal cover is obtained by modifying the front surface 272 and the rear surface 282. The surface 272 can be formed with a concave cylindrical shape, with the axis of the cylinder parallel to the length of the lens 250. The surface 282 can be formed with a negative cylindrical formai, the cylinder axis again 'parallel to the length of the lens 250.

Referring now to FIG. 8, there is shown an illustrative optical system incorporating the lens of FIG. 7. Baffle 300 is placed between scene 24 and lenses 106 and 108. In a preferred embodiment, baffle 300 is part of housing 100. Baffle 300 is angled at an angle? about 45 degrees with the vehicle horizontal. Deflector 300 defines opening 302 open to scene 24 on the front of the vehicle. The opening 302 could be trapezoidal, so that the projection of the opening 302 on a vertical surface would form a rectangle on the vertical surface similar to the aperture 102. The aperture 302 is as small as possible without restricting the light projected by the lens 106 to any point in the upper sub-window 94 or by the lens 108 to any point in the lower sub-window 96.

The lens 250 is mounted on one side of the aperture 302. The width of the lens 250 is approximately the same as the diameter of the lens 106 or 108. The lens 250 is oriented so that the beam 251 travels approximately above the vehicle and Lightning 260 travel approximately the front of the vehicle. The lens 250 is positioned so that a defocused, inverted image of the lens 250 is projected by the red lens 106 onto an edge of the image detector 34 between line 304 and line 306 to form the red sky image 312. The lens 250 is also placed, so that an out-of-focus, inverted image of the lens 250 is projected by the red attenuation lens 108 on the edge of the image detector 34 between line 308 and line 310 to form the attenuation sky image. of red 314. Due to the parallax error, line 306 is above the lower edge of upper sub-window 94 and line 308 is below lower sub-window 96. Active length of lens 250 is sufficiently made short to allow the total active length to be projected in the regions between lines 304 and 306 and between lines 308 and 310.

The red sky image 312 and the red attenuation sky image 314 are scanned in the processing and control system 36. Because only a rough image is required for the on / off control of the headlight, it is not a great detriment that the red sky image 312 and the attenuation red sky image 314 are not in focus. In one embodiment, a threshold is compared to the light levels detected by the image detector 34. If the light levels are above the threshold, the headlight 22 is turned off. If the light levels are below the threshold, the headlight will turn on.

The pixel locations for the red sky image 312 and the red attenuation sky image 314 are correlated, so that the readings can be compared for each 10 degree incremental increase. A higher attenuation ratio of red indicates that the blue sky is being observed. In one embodiment, a lower threshold point could be used to turn the headlight 22 on and off for a blue sky than for a cloudy sky.

In another modality, the threshold is hysteretic. In yet another mode, a delay time is used after the last on / off transition. These two modes could prevent the headlight 22 from frequent off-ignition transitions around ^ _ ^^^^^^ ^^^^^^^ tMa¡t¡M¡mámM * im of the change point While the improved ways of carrying out the invention in detail have been described, there are other possibilities within the spirit and scope of the present invention. Those skilled in the art to which the invention relates will recognize various alternative designs and embodiments for the practice of the invention as defined by the following claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, the content of the following is claimed as property.

Claims (39)

1. An image forming system for use in a vehicle headlight control system, characterized in that it comprises: a housing defining an opening, the opening generally opens towards a scene; an image detector within the housing opposite the aperture; a support within the housing defining a first opening between the aperture and the image detector and a second aperture between the aperture and the image detector; a first lens in the first aperture, the first lens functions to focus the light of the scene on a first portion of the image detector; Y a second lens in the second aperture, the second lens functions to focus the light of the scene on a second portion of the image detector, the second portion of the image detector is separated from the first portion

2. An image forming system as in claim 1, characterized in that the first lens further functions to focus the light at a first wavelength on the image detector and wherein the second lens functions to focus the light at a second length of wave over the image detector.

3. An image forming system as in claim 2, characterized in that the focal length of the first lens at a first wavelength is substantially the same as the focal length of the second lens at the second wavelength.

4. An image forming system as in claim 2, characterized in that the first lens further functions to attenuate the substantially cyan light and the second lens further functions to substantially attenuate the red light.

5. An image formation system as in claim 1, characterized in that the image detector has a low resolution.

6. An image forming system as in claim 1, characterized in that it further comprises: a baffle extending from an area between the first lens and the second lens to the detector d 1 image, the deflector works to reduce the light passing to through the first lens colliding with the second portion of the image detector and to reduce the light passing through the second lens from colliding with the first portion of the image detector.

7. An image forming system as in claim 1, characterized in that it further comprises a shutter that functions to reduce the intensity of light entering the opening.

8. The image detector as in claim 7, characterized in that the shutter is an electronic window.

9. The image detector as in claim 1, characterized in that the aperture defined in the housing is positioned at a distance from the first and second lenses that is at least twice the distance between the image detector and the first and second lenses. . *, _ ^? gg ^

10. The image detector as in claim 1, characterized in that the first portion of L housing defining the opening is placed parc? block the light that would otherwise travel through. ' first lens and would crash like light scattered over the second portion of the image detector and wherein a second portion of the housing defining the aperture is placed to block light that would otherwise travel through the second lens and would hit like lu? . scattered over the first portion of the detector d 'image.

11. An image forming system as in claim 1, characterized in that it also comprises a light separation lens located in the aperture, the light separation lens functions to gather light from a wide angle of the scene and to redirect the light gathered towards the first lens and the second lens.

12. An image forming system as in claim 11, characterized in that the light of a wide angle comprises an arc of light substantially above the vehicle through the light substantially in front of the vehicle.

13. An image forming system for use in a headlight control system, characterized in that it comprises: a housing defining an opening that opens: in general towards a scene in the front of the vehicle; an image detector located inside the room; Y a light separation lens located near the aperture, wherein the light separation lens functions to gather the light rays from a region defined by a vertical arc extending substantially above the aperture, to substantially the front of the aperture. the aperture and wherein, the light separation lens re-directs the assembled light rays towards the image detector.

14. An image forming system as in claim 13, characterized in that the light separation lens further functions to gather the light rays from a region defined by a narrow horizontal arc in general at the front of the aperture.

15. An image formation system as in claim 13, characterized in that the image detector is comprised of a plurality of pixel detectors.

16. An image forming system as in claim 15, characterized in that the light separation lens functions further to gather the light rays of the elevationally separated regions and to re-direct the assembled light rays of each region ele vacionally. and separated to a different group of pixel detectors, whereby the image detector detects the light level at different angular elevations.

17. An image formation system as in claim 16, characterized in that the elevationally separated regions comprise 10 degrees of elevation.

18. An image formation system as in claim 15, characterized in that it also comprises: a first sub-window of pixel detectors; a second sub-window of pixel detectors; a red lens within the housing between the light separation lens and the image detector, the red lens functions to substantially project the red components of the light rays re-directed onto the first sub-window; Y a red attenuation lens within the housing between the light separation lens and the image detector, the red attenuation lens functions to substantially project the red attenuation components of the re-directed light rays onto the second sub -window.

19. An image forming system as in claim 13, characterized in that the light separation lens comprises: a top section with a front surface angled with respect to the vertical surface and a rear surface, comprising a plurality of triangular shapes, each triangular shape having a lower rear side and a rear upper side forming a vertex pointing generally away from the surface front, whereby the rays of light entering the upper section front surface from angles between approximately the vertical and the angle of inclination of the front surface of upper section, are diffracted by the front surface of upper section, are reflected from the lower rear side and are diffracted by the upper rear side, which leaves the lens substantially horizontally; Y a lower section with an angled rear surface relative to a vertical surface and a front surface, comprising a plurality of triangular shapes, each triangular shape having a lower front side and a front upper side forming a vertex pointing, in general, away of the rear surface of the lower section, whereby the rays of light entering the front surface of the lower section with angles between approximately the horizontal and the angle of inclination of the rear surface of lower section, are diffracted by the surface lower section front and diffracted by the front rear surface, which leaves the lens substantially horizontally.

20. A system for controlling at least one headlight, characterized in that it comprises: a headlight controller in communication with the headlights, the headlight controller operates to turn the headlamps on and off based on a received on / off control signal; an image detector comprising an array of pixel detectors; a lens system that functions to gather the light rays from a region defined by a vertical arc extending from substantially above the vehicle to substantially at the front of the vehicle and to redirect the assembled light rays to the detector. image; Y a processing and control system in communication with the image detector and the headlight controller, the control and processing system works to read the light levels of the pixel detectors and to determine the on / off control signal based in comparing light levels to a threshold.

21. A system for controlling at least one headlight as in claim 1, characterized in that the lens system includes a light separation lens and the system further comprises: a first sub-window of pixel detectors; a second sub-window of pixel detectors; a red attenuation lens within the housing between the light separation lens and the image detector, the red lens functions to substantially project the red components of the light rays re-directed onto the first sub-window; Y a red attenuation lens within the housing between the light separation lens and the image detector, the red attenuation lens functions to substantially project the red attenuation components of the re-directed light rays onto the second sub -window.

22. A system for controlling at least one headlight as in claim 21, characterized in that the processing and control system works me m? á jk in addition to determine the threshold based on the color components projected on the first and second sub-windows.

23. A system for controlling at least one headlight as in claim 21, characterized in that the processing and control system further functions to determine whether the region defined by the vertical arc forms the blue sky image or a cloudy sky and to use a threshold lower for the blue sky than for the cloudy sky.

24. A system for controlling at least one headlamp as in claim 20, characterized in that the processing and control system further functions to determine the on / off control signal based on comparing the light levels to a hysteretic threshold.

25. A system for controlling at least one headlight as in claim 20, characterized in that the processing and control system further functions to determine the on / off control signal based on the delay time of a previous change in the control signal from MÉMÉM turned on / off.

26. A system for controlling at least one headlight, characterized in that it comprises: an image formation system that functions to gather the light of a scene in front of at least one headlight and to determine the intensity of the light collected; a shutter between the image formation system and the scene, the shutter functions to attenuate the intensity of the scene light; Y a processing and control system in communication with the image forming system and the shutter, the processing and control system operates to read the light levels of the image forming system and to control the shutter attenuation of the light based on the light levels.

27. A system for controlling at least one headlight as in claim 26, characterized in that the shutter is an electrometric window.

28. A system for controlling the headlights of a vehicle, characterized in that the system comprises: headlights of vehicles; at least a first light detector operated to output a first signal sensitive to incident light on a surface of at least one first light detector; at least one second light detector operated to output a second signal sensitive to incident light on a surface of at least one second light detector; a lens system operated to collect light from above a vehicle and direct the light collected on at least one first light detector and collect light from the front of the vehicle and direct the light collected on the second light detector, so which the first signal is proportional to the light level above the vehicle and the second signal is proportional to the level of light at the front of the vehicle; and a processing and control system coupled to the headlights of the vehicle, at least a first light detector, and at least one second light detector, the processing and control system operates to control the headlights responsive to at least the first and second signs.

29. The system of claim 28, characterized in that the lens system includes a first lens for directing light from above the vehicle to at least one first light detector.

30. The system of claim 29, characterized in that the first lens also directs the light from the front of the vehicle.

31. The system of claim 30, characterized in that the lens system further includes a second lens for focusing the light directed from above the vehicle by the first lens onto at least one first light detector.

32. The system of claim 31, characterized in that the lens system further includes a third lens for focusing the front light The vehicle will be on at least one second light detector.

33. The system of claim 29, characterized in that the lens system further includes a second lens for focusing the light directed above the vehicle by the first lens on at least one first light detector.

34. The system of claim 33, characterized in that the lens system further includes a third lens for focusing the directed light from the front of the vehicle by the first lens on at least one second light detector.

35. The system of claim 29, characterized in that the lens system further includes a second lens for focusing the light from the front of the vehicle on at least one second light detector.

36. The system of claim 28, characterized in that the lens system further includes a first lens for directing light from the front of the vehicle to at least one second light detector.

37 The system of claim 36, t ^ ** »* ^^ ^ ¿^ -.-aafc,," S ..; ^ _, jj ^, *. ".... * ^^^ - < - characterized in that the lens system further includes a second lens for focusing directed light from the front of the vehicle by the first lens on at least one second light detector.

38. The system of claim 28, characterized in that at least one first light detector comprises at least one pixel of an image array detector.

39. The system of claim 28, characterized in that at least one second light detector comprises at least one pixel of an image array detector. SUMMARY OF THE INVENTION An image forming system for use in a vehicle headlight control system includes an aperture, an image detector, a red lens that blocks complementary red light between the aperture and the image detector, and a complementary lens. of red that blocks the red light between the aperture and the image detector. Each lens focuses the light on a different sub-window of the image detector. The image formation system allows the logic of processing and control to detect the presence of headlights in vehicles in the opposite direction and taillights in vehicles that S? approach from behind, for the purpose of controlling the headlights. A light separation lens could be used to redirect the light rays from a separation arc above the vehicle to the front of the vehicle in substantially horizontal rays. The light separation lens is formed by the image detector to produce an indication of the light intensity at various elevations. The processing and control logic us.a the intensity of the light to determine if the headlights should turn on or off. Could , -gaft »-, -. ^ aa? t: a shutter is used to protect the elements of the imaging system from excessive exposure to light.