Patent Application
20130258688
The fundamental ideas behind this application had risen out of the necessity to find a design solution for the complex subject of vehicular lighting devices which until present remain manually controlled with relatively poor performance results in respect to the forward direction and around curve visibility, back-dazzle and incoming traffic blinding effects. This application comprises of a microprocessor controlled headlight system providing adaptive output response of all illumination parameters as they are defined by luminous intensity, distribution of the luminous flux to needed to create the optimum road illumination patterns, by the direction of illumination as well as the necessity to change the emitters' radiated spectrum for improved visibility and for signaling purpose. The control system is designed to automatically respond to the external light conditions and relies on electronic feedback signals received from photo-sensors or video input, angular position encoders, accelerometers and other sensors which are aiding in the driver's action for lights switching hence providing improved driving comfort and safety. National SAE and international ECE standards and regulations for installation and performance of motor vehicle lighting were followed in this design, as they are stipulated by the Federal Motor Vehicle Safety Standard No. 108 which also incorporates SAE technical recommendations for North America and Canada. These regulations require an asymmetrical low beam oriented downward (low light on the left side of road) and a symmetrical narrow high beam focused slightly to the right side of the road.
This LED/Laser vehicle illumination system is designed as a headlamp/signaling headlamp that delivers a low beam of light, a high beam with reduced blinding effect to the opposite traffic and will provide colored (yellow/orange spectrum) direction signal lights or red for vehicular hazard warning signals. These functions are achieved with or without auxiliary emitter components by changing the emission spectrum of the already present LEDs situated on the Left and Right side of the headlamp assembly. The headlamp presented in this application is also equipped with upright light control to reduce back-dazzle while allowing for road sign reading, and will illuminate the curved roads ahead prior to engaging the turn and without diminishing the forward visibility and without involving the work of any electromechanical motion devices. Unlike the traditional manual lights switching from one beam state to another (low to high or high to low beam), the herein system introduces an adaptive light control principle which automatically adjusts its output parameters of luminous intensity and directivity as it is dictated by input parameters of ambient light, the incoming traffic lights, the intended direction of travel or by the overall roadside illumination conditions. Voice activated light control functions may be implemented in the microprocessor firmware.
In the present market, the design of the vehicular (automotive) headlamps may be characterized by fixed emitting fixtures presenting a fixed luminous intensity with unidirectional orientation of the main light rays (vectors). The photoelectric characteristics of these headlamps are controlled manually which in fact adds to the burden of night driving, increasing driver's response time to avoiding obstacles and reduces his perception in distinguishing shapes and the road topography due to the high contrast and penumbra effects created by such static design concepts. Due to the sudden change in road illumination intensity during high-low beam switching, there are seconds of blindness following this action which have negative results in driving performance and had proven to be a source of accidents.
Some more advanced designs include mechanized headlamps which respond to the driver's change of direction and improve the side and curve visibility. Though, such headlamps are complex in their mechanical design, expensive to maintain or replace and have the main disadvantage of taking the front illumination and displacing it sideways which in final diminishes the forward illumination with unexpected results.
A view at the contemporary automotive control systems reveals that from navigation to brakes and many other driving or safety features are computer controlled while the vehicular illumination systems remain manually operated thus presenting a subjective rigid design with limited performance and presenting deficiencies which are no longer suitable for a modem vehicle. Novel systems are demanded by the market and a unique solution is presented by this application.
Experimentation with various geometrical shapes and angle of distribution of the light emitted by LEDs and Laser sources lead to the conclusion that an asymmetric apparatus having a variable geometry that contains the emitting light sources positioned at predetermined angles produced the widest uniform illumination pattern which when individually controlled in intensity and direction created the best overall illumination patterns in conformance with the vehicular illumination standards in effect.
Along with introducing the concept of angular displacement of the light sources in five or more directions of illumination ex., Up/Down/Left/Right and the Center for a selective directional emission of light rays, the herein application invokes an adaptive discrete control of light intensity and a switching algorithm of emitters, individually and in groups for an efficient electric power management and omnidirectional dispersion of light which can be selectively oriented.
Having a radiometric analysis of the light emitting sources, the herein design saves electrical energy [Watt*Hour] thus increasing light efficacy through the emitters switching technique and through the PWM (Pulse Width Modulation) principles applied to each directional emitter-module (Left, Right, Up, Down and Center modules). From a photometric point of analysis the PWM controls the light intensity of each emitter-module and relies on the feedback signal delivered by the photo-sensors or cameras which in turn assures a maximum luminous intensity [lm] in the driving direction after compensating for the incoming traffic and surrounding light sources. In effect, such adaptive light control is designed to minimize the glare while enhancing the quality of the allover illumination and therefore limiting the negative effects of the eye's difficulty to adapt to sudden light intensity changes.
This invention is focused on reducing drastic changes in the illumination levels (as encountered when changing from high beam to low beam) and produces constant illumination over the whole scene, issue not presently addressed by any of the headlamp devices. Illumination levels over the scene produced by traditional sources can contain either insufficient or over illuminated portions, phenomenon associated with a corresponding decrease in human reaction time due to the inertial effect on the eye receptors recovery called the after image effect. A much wider area of illumination provided by this design facilitates early detection of obstacles thus limiting the long term driving stress.
By controlling the left and right fields of illumination this design prevents the formation of direct glare (the presence of a bright light in the visual field) to the incoming traffic.
Some of the most important features of the present asymmetrical geometry concept applied to vehicle headlamps are; a) wide area of visibility over the shoulder and over curved roads without the aid of motion devices, b) elimination of the scotoma effect on the eye by extending the visibility in critical zones situated ahead and sideways.
Studies by Brebner and Welford, 1980 and Luce (1986) establish that the mean simple reaction (the acknowledgement of visual stimuli but without including a physical response time) is approximately 190 ms, while Eckner et all. (2010) determines it to be 268 ms. The average time calculated for the mean simple reaction from these studies is averaging at 229 ms, and it becomes even longer for images picked around the eye edges and at night time.
The human biological response time to light stimuli calculated from the moment of perception to the moment an image is created on the brain is called recognition reaction time and extends to approximately 384 ms, according to Eckner et. all study (2010).
If we consider that at the actual cruising speed of a vehicle is 65 MPH (or 104.6 Km/h) such vehicle will advance by a distance of 95.3 Ft (29.06 m/s) every second. Considering that the human recognition reaction time is approximately 384 ms (or 0.384 s), the distance the same vehicle will travel before the driver would have reacted to the visual stimuli is 36.59 Ft (11.15 m). This is equivalent with driving blind for 36.59 Ft, situation that could be only aggravated by a limited peripheral illumination delivered by the regular headlamp designs. An additional visual impediment is created by the fixed illumination field of the traditional headlamps which widely vary among manufacturers. Such negative effects are compensated for in this invention through the adoption of an adaptive illumination system that generates a wide view pattern which is selectively adjusted in intensity and direction without compromising luminosity via restrictive geometrical or optical methods.
The herein design addresses all the functional parameters of a vehicular headlamp and improves the overall visibility by producing five (in this application) or more independent adaptive illumination patterns, and extends the distance and angle of view through its automatic light intensity control which receives feedback from automotive ambient light sensors (ALS). The negative effects created by the time delayed human reaction is reduced in the herein design by constantly adjusting the forward and side illumination, hence allowing for early detection of obstacles which in turn results in a longer time to react and to higher road awareness with reduced driver fatigue. This invention proposes a multiple light emitting modules assembled on a number of geometrical facets of a headlamp, which are positioned at various angles measured from the center module/facet so that the light vectors (300) of the central module/facet are oriented forward, the Left and Right facets' vectors (200) are oriented sideways, and oriented downward for the Up and Down facets, as depicted in
This headlamp and signaling system relies on proprietary real-time microprocessor control routines, and a data acquisition unit running independent of the main vehicle computer and common interfacing is limited to displaying various functional states or malfunction of the illumination system on the vehicle monitor. A separate display monitor may be also provided for displaying the headlamp's operational status.
Constructive and Functional Objectives Pursued and Implemented by this Application
The main constructive and functional objectives of this application for which the claims are made, are enumerated below:
This description explains the construction and the operational principles on which the claims are founded and is understood that such claims shall include any and all of the implicit theories, construction, technology and functionality as presented within this text.
An asymmetric geometry headlamp concept designated for vehicular external illumination was designed to produce light with adaptive parameters of luminous intensity and direction (the magnitude and the angle of the light vectors) and to provide multiple modes of operation pertaining to direction change signaling, distress signals and security features as it is introduced by this application. The asymmetric design of the light emitting system may be understood as a geometric body having the property to generate light in all desired directions by using arrays of emitting devices placed on its various surfaces named facets or modules, which facets are situated at various angles in relation to each other so that the total illuminated area will cover a 2PiRadian solid angle.
The asymmetric geometry design of the headlamp is depicted in detail in
The shape of the headlamp is determined by the surface area and the angular orientation of the respective facets which may be customized for every individual type of vehicle. The terminology further used within this text will make reference to facets when describing geometric constructive parts of the headlamp and will use the term module when referring to the whole assembly of the facet geometrical structure including the light emitting devices and their driver control circuitry viewed as an integral unit.
The design relies on the principle of dividing the vehicle illumination pattern into five or more independently controlled illumination zones as being defined by the five (or more) facets of the angular geometry of the headlamp body. Each facet of the headlamp is equipped with a multitude of LEDs and/or Laser emitters which are forming independently controlled zones of illumination and signaling. All the illumination parameters of intensity, directivity and spectrum are controlled by a microprocessor and no moving parts or actuators are employed in the construction of this headlamp.
A series of photoelectric (ALS) and/or video sensors produce the feedback signals used in controlling the intensity, directivity and color spectrum of the light patterns generated by the LED/Laser emitters.
A group of accelerometers and angular encoder sensors provide the feedback signals within the control loop addressing the sideway illumination, the direction change signals and also trigger the automatic hazard signaling.
A simplified schematic of the microprocessor control system and the connectivity to sensors, drivers and the light emitting device assemblies are shown in the block diagram of
A power supply regulator (105) receives the electrical power from the vehicle battery (117) through the intermediary of a key switch (118) which may be electronic or mechanical, and regulates its voltage and limits the current to the levels required by the control circuitry.
The control system is comprised of a microprocessor (102), clocked by an oscillator (116) and powered through the vehicle key (115). A series of sensors, namely represented by accelerometer/s and position encoder(s) (106), photo-detectors and/or video cameras (104), are connected to the microprocessor control system.
A digital and analog microprocessor interface circuitry is represented by a series of signal conditioning amplifiers (113), analog to digital converters (112) and logic gates (114), are connected to the input/output or I/O Bus, (I/O 0 to I/O 3) providing the input feedback from photo-sensors and/or video cameras and the logic controls functions to the microprocessor.
The LED/Laser devices (103) are driven by Drivers (107, 108, 109, 110, 111) and are controlled by the logic Enable Bus (EN1 to EN5) which select the direction of illumination namely Center, Up, Down, Left and Right, while the pulse width modulated bus PWM-Bus (PWM1 to PWM5) outputs the signals necessary to control the luminous intensity of the emitting devices (103).
The light emitting devices (103) and photo-sensors (104) for the planar design (in this example) configuration are assembled on an asymmetric geometry printed circuit board depicted in
The angle at which the headlamp facets are disposed are calculated accordingly to the emitting devices optical characteristic graph of luminous intensity (I) vs. theta angle (Degrees) and serve the purpose to generate a wide and uniform spatial light distribution pattern. The facets may be planar of curved to form a concentrator-reflector of a spherical, cylindrical, ellipsoidal parabolic, hyperbolic geometry, or of any combination thereof. These components are enclosed in a headlamp housing (120) which is protected by a transparent antiglare front cover. The interior surface of the headlamp housing (120) is clad with a reflective substrate that captures the indirect rays of light and contains them within a limited frontal area.
Drawings in
The lens (119) is optional and may be eliminated when high power Laser emitters requiring collimation, are used. The embodiment of the Central facet shown in
The Up facet(s) is tilted forward toward the symmetry axis at an angle which is determined by the LED manufacturer's graph of Intensity (I) vs. angle [I=f(Angle)], such that a uniform wide angle of luminous dispersion is obtained by superimposing light fields from all emitters as it is shown in
The flowchart in
At the time the contact key is inserted and turned in the first position, the lighting control system is energized and the microprocessor runs its register reset routine, checks the sensors output voltage range and runs a calibration check program. The light/video sensors for left side and right side driving conditions are selected manually and depending by the If-Then=YES condition a day time run routine is set for controlling the day light headlight intensity and turns on the position lights. Otherwise, when If-Then=NO, the microprocessor runs its night time routine when the intensity and direction of illumination vectors are automatically controlled with feedback signals received from the light/video sensors and from accelerometers and/or position encoders. In case that incoming traffic is detected per
For driving on multilane roads, both left and right facets/modules will dim their side illumination vectors (200) to comfortable intensity levels per
In single car on the road driving conditions, the illumination is set at its maximum levels in all directions with all five facets/modules operating close to 100% intensity as shown by the illumination pattern in
The use of video arrays or video cameras within the light feedback control loop allows for early detection of subjects situated on the road beyond the limits of the visible light field, by sensing the IR (infrared) spectrum of the subject (invisible to the human eye) and forcing the headlamp into its maximum intensity of visible spectrum in response. This early detection IR system may be fixed or adjustable in range, to cover the center of the road ahead or the whole solid angle of 2PiRad the headlamp is capable of illuminating.
The block diagram in
An ON/OFF switch (118) supplies the battery power to the circuitry through the intermediary of a Volt/Current stabilized power supply and regulator module (105) providing the desired voltage level for the interface circuits, microcontroller (102) and the LED driver circuitry (107) (108) (109) (110) and (111).
A manual override switch (115) is provided as a safety solution in case of system fault or errors, which when activated returns the main control operations of Low/High beam changing and signaling lights to the driver.
When the Power ON is activated through switch (118), the microcontroller is reset and its active memory deleted of any prior settings generated by the program's run-time algorithms.
All the sensors connected to the I/O bus are checked against calibration preset values and their actual signal is then conditioned and sent to their corresponding input ports at the microcontroller (PIC18 microcontroller or other suitable type may be used).
Other preliminary conditions are set in hardware for Day/Night status and used for the PWM threshold levels which are then compared with the light sensor signals to determine the proper illumination level outputted by the light emitting LEDs located in the headlamp modules in order to generate a certain luminous intensity. If incoming traffic is sensed, the Left side of the head lamps (for Right side driving countries) is turned Low by PWM 1 to 4 circuitry acting on intensity vectors (200), thus reducing the blinding effect to the opposite traffic, as seen in
The photo-sensors continuously evaluate the luminosity of the path ahead and adjust to lower or higher levels the UP and CENTER sections of the headlamps acting as a proportional and compensative luminosity control, for improved visibility.
During the normal night driving conditions, all sections of the headlamps UP-Down-Left-Right and CENTER are lit dispersing light over a 2Pi Radian area with uniform intensity over the whole scenery as seen in
The SAE standard does not require an upper cut-off for the Low Beam light but this application provides for such capability by selecting the initial set angle of the UP facet of the headlamp assembly.
In order to conform to the SAE and ECE standard recommendations, the LEDs (103) are selected to radiate light in the Cool-White spectrum, and the headlight back-dazzle effect is done by adjusting the angle of the UPPER facet along with light intensity control.
Each LED headlamp module is driven by specialized LED driver circuits (107) (108) (109) (110) and (111), having individual inputs for PWM1-4 (Pulse Width Modulation) and EN1-4 (Driver Chip Enable) to enable individual modules, each signal being provided by the PWM Bus and EN Bus, of the microcontroller output ports P0 through P7.
Two or more Left and a Right photo-sensors (ALS) (104), are situated on the LEFT and respectively RIGHT modules of the LED headlamp assembly but not necessarily situated within the assembly in order to avoid light interference effects, and are having the role of detecting the outside illumination level and provide a proportional signal to the luminous intensity control circuitry. The same signals received from photo-sensors (104) are separately amplified (113) and converted from analog to digital by the A/D converters (112), then applied to an “AND” logic gate (114) for USA or EU (Europe) driving standard selection, done through the Country Selector switch and applied to the I/O3 port programmed as digital input.
The analog signals from the Left and Right photo-sensors after proper amplification by AMP 1 (113) and AMP2 (113) are connected to the, I/O1 and I/O2 ports which are programmed as analog input channels designated to process signals with a continuous variation in time.
The High Beam is generated by the CENTER module which is driven by LED driver (107) and is equipped with a number of reflective poly-parabolic shapes and condenser lenses used to concentrate the light into a narrow spot shooting at high distance, which section is also controlled by the PWM4 modulator controlling the high intensity of the Low to High beam levels on a linear response characteristic. As seen in
The light intensity and direction of the light rays are both continuously adjusted so that the eye is not exposed to sudden changes in luminous intensity hence eliminating the eye adaptation time inherent in standard headlamp designs.
Accelerometer(s) (106) connected to the analog port I/O0 of the microcontroller, detect changes of direction in the horizontal plane along X, −X axis for Left-Right vehicular motion and accordingly will generate a signal to increase the side illumination in the direction the change occurs. This in-curve illumination is part of a programmed predictive control system routine, is fully automated and controlled by information received from accelerometers and/or light detectors (104) and does not imply any electromechanical or mechanical actuation or motion.
Changes along the Y,−Y (along traveling direction) axis detected by the accelerometer(s) (106) will indicate an acceleration or deceleration of the vehicle. A sudden and high rate of deceleration (ex. during a strong and sudden braking, or deceleration determined by frontal impact) will trigger the distress red light blinking signaling alerting the other drivers. A built-in differential circuit alerts for fast deceleration which is then referenced to a preset differential value for speed dv=v2−v1 (where v2=cruising speed of vehicle, and a fixed v1˜40 mph speed reference) at which moment the distress lights will start flashing red light in order to alert the rear traffic about critical drop in speed and/or fast deceleration conditions.
It is understood that the change of direction signaling remains completely under driver's manual control at all times, but it may be automated if used in ROV (remote operated vehicles) applications.
A direction change signal initiated by the driver of the vehicle will override an earlier activated distress signal for the duration of signaling so that there will be no confusion about the driver's intention to indicate the change in driving direction.
Three-axis accelerometers having a third degree of detection along Z, −Z axis (vertical plane), may be used to maintain road illumination even during high vertical swings and such functions may be associated with other performance factors of the lighting system as they could become desirable at a later time.
