MX2007004457A - Method of controlling an electrochromic mirror and an electrochromic system which are intended for a motor vehicle - Google Patents

Abstract

The invention relates to a method of controlling an electrochromic mirror and to an electrochromic system which are intended for a motor vehicle. The inventive method comprises the following steps:a) detection of the incidence on the mirror of a light signal with a light intensity above a pre-determined threshold;b) upon detection of said signal, the electrchromic mirror darkens to a pre-fixed maximum level of darkness;c) when the light signal is no longer incident on the electrochromic mirror, the mirror lightens to a minimum level of darkness, thereby improving the driver's view of the exterior of the vehicle;d) the electrochromic mirror is lightened or darkened to an intermediate level;e) detection of the incidence on the mirror of a subsequent light signal with a light intensity above a pre-determined threshold;f) upon detection of said signal, the electrochromic mirror is darkened from the intermediate level to a maximum level of darkness;and g) when the subsequent light signal is no longer incident on the electrochromic mirror, the mirror returns to the intermediate level of darkness.

Description

Method of control of an electrochromic mirror and electrochromic system, applicable to a motor vehicle TICAL FIELD The present invention relates in general and in a first aspect to a control method of an electrochromic mirror, applicable to a rearview mirror of a motor vehicle, and more particularly to a method to improve the efficiency of an electrochromic mirror before repetitive dazzleings. The invention also concerns, in a second aspect, an electrochromic system applicable to a rear-view mirror of a motor vehicle using the proposed control method.

STATE OF THE PRIOR ART The problem of glare during driving is really important, since it affects the capabilities of the driver of a vehicle. The glare can be caused both by vehicles approaching the aforementioned vehicle and by vehicles following it. These vehicles produce glare because they either drive with the lights on, or with poor adjustment of the dipped beam. In addition, and due to the increase in the number of off-road vehicles or family type (which have their headlights located at higher than standard vehicles) the problem has increased significantly. Basically, glare can be described as the sensation produced by a. light level in the visual field that is considerably higher than the level at which the human eye is adapted. Glare interferes with visual perception, causes irritation, discomfort and even loss of visual performance. This also greatly increases eye fatigue. In the context of a driver in good health, the glare can be divided into two main categories: Blinding glare: The sensation of blindness is so severe that even for a considerable time after the disappearance of the stimulus, no object can be easily seen or distinguished. This is the typical glare suffered when a driver of a frontally approaching vehicle forgets to turn off the headlights. Annoying glare: It is the glare that produces discomfort or irritation without interfering with visual performance. It has been shown, however, that this kind of glare can cause fatigue and result in the driver making an error.

The blinding glare is the most severe, as it seriously impairs the visual function of the driver, not allowing him to make accurate decisions. In addition, there is an additional effect: "photo-stress", also known as "Troxler Effect". The "Troxler Effect" describes the fact that once the cause of the glare has disappeared, the driver for some time still has impaired visual functions. This effect can increase the reaction time of the driver to about 1.4 seconds. Although generally annoying glare does not seriously impair vision, it is also undesirable because it can startle or distract the driver. It can also cause blinking, squinting, aversion ocular and fatigue. The ability to cope with annoying glare varies depending on the time it occurs and the individual who suffers, but as a general rule, the older the driver, the worse the effects. Several solutions to this problem have been proposed and have been available in the market for some time. Historically, the first solution was the use of prismatic mirrors. These mirrors have two driving positions, one of high reflectance and the other of low reflectance, which can be switched depending on whether there is a glare condition or not. The main disadvantages of this system is that it is only applicable to the interior mirror and that, in addition, it usually requires the intervention of the driver. Approximately twenty years ago, the first mirrors with the ability to regulate, electrically, the intensity of light, also known as electrochromic mirrors, which can adjust their reflectance continuously between a state of high reflectance and a state of low reflectance, typically between 70% and 7%. These devices incorporated an electronic activation unit that controls the glare conditions and automatically decides when to darken the mirror. A typical configuration employs two light sensors, one to control the ambient light and the other to control the light coming from behind, which causes glare when reflected in the mirror. Depending on the severity of the glare condition, the activation unit decides to darken the mirror to reduce the amount of reflected light and thus reduce glare. The "algorithm of taking decisions "of these systems is quite simple: while the glare persists, the system keeps the mirror obscured, and once the glare condition has disappeared, the system returns the mirror to the level of high reflectance. It takes approximately five to twelve seconds for the technology to change from a state of high reflectance to a state of low reflectance, however, more attention should be paid to the physiological processes that govern the adaptation of the eye to glare, mainly in terms of The first mechanism to reduce the amount of light is to reduce the diameter of the pupil, however, the pupil has a response time of approx. 300 ms before starting to contract, this time increases as individuals get older. In addition, the speed at which the pupil can contract also decreases with age. Therefore, it can be concluded that the greater the individuals, the worse the response of their pupils to glare. When the contraction of the pupil is not enough to correct the glare situation, the sensitive cells change their response. This second mechanism usually takes five to thirty minutes to complete. Taking into account these basic notions about the physiology of the eye, it is possible to deduce that sensitivity to glare depends on three main factors: 1) Age: The primary factor when determining individual differences in sensitivity to both, the glare of Blindness and annoyance is the age of the person, due to its slow physiological adaptability and its greater recovery time compared to "photo-stress" (Troxler Effect). 2) Glare intensity: It is obvious that the brightness is directly proportional to the intensity of the glare source, and therefore, the glare is proportional to the luminosity of the headlights of the vehicles. 3) Frequency: If the environment presents great contrasts, for example during night driving, the eye has to adapt from low light levels to high levels and the opposite, in short time intervals. This transient adaptation soon ends in visual fatigue that increases sensitivity to glare. So far it seems clear that although a current electrochromic mirror can help reduce glare, especially at night, its performance, using the "conventional decision making algorithm" discussed above, is not enough because These mirrors can not avoid the first "high intensity light impact" associated with glare, nor the repetitive glare produced by a vehicle that follows us closely. An example of a system using one of said electrochromic mirrors is that proposed in the patent application W099 / 22964A1, which concerns a rear-view mirror system with automatic light attenuation, for motorized vehicles, which generally comprises an element of electrochromic mirror whose degree of reflection can be modified by applying a constant voltage. Said system comprises sensors for detecting Ambient light and glare lights coming from vehicles coming from behind. It also includes a control unit that converts the signals coming from the sensors into a constant control voltage to activate the electrochromic element, as well as a power supply to feed the sensors and the control unit. No methods of utilization are proposed other than that provided by the conventional algorithm explained above. On the other hand, an example of a proposal that aims to improve the control of an electrochromic mirror in the face of glare situations is that provided by the patent application US2004 / 0099786, which concerns a set of antiglare mirror and a method of controlling the reflectance thereof. The set includes an electrochromic rearview mirror, two backlight sensors, and a comparative controller. The sensors are located in two different areas, partially overlapping, to detect the incidence of a glare signal in said two zones. The intensities of the incident light in the two zones are compared to obtain a difference, according to which the reflectance of the electrochromic rear-view mirror is adjusted. This is intended to achieve a more realistic control of the electrochromic mirror, although with a very specific application that only take into account the different degrees of incidence that a light signal generating a glare can have on the same rear view mirror, but not how to adapt the control of the mirror, not only to the intensity of the light that causes the glare, but to other characteristics of the phenomenon, such as its repetition in time.

Explanation of the invention It appears necessary to provide a control method of an electrochromic mirror that improves its operation compared to that obtained up to now with the use of the "conventional decision-making algorithm" previously mentioned, as well as that contemplates driving other issues not addressed by the state of the art, in particular those relating to alleviating the effects caused by the first "high intensity light impact" associated with glare, and those caused by the repetitive glare produced by a vehicle following us close up. The present invention concerns, in a first aspect, a control method of an electrochromic mirror, applicable to a rear-view mirror of a motor vehicle, of the type comprising the following stages in a sequential manner: a) detecting the incidence on said mirror a luminous signal with a light intensity above a certain threshold, preset, capable of causing the mirror to darken to a maximum level of darkness, preset, said signal being representative of a glare, b) darkening to said maximum level of darkness, prefixed, said electrochromic mirror after at least one of said detections, to face said glare, and, c) clarify, after the cessation of the incidence of said luminous signal, to a minimum level of darkness said electrochromic mirror, facilitating the vision from the outside of the vehicle, Said steps a), b) and c) are already known in the state of the art, and specifically contemplated by the "conventional decision making algorithm" explained above. What characterizes the method proposed by the present invention is that when at least the conventional stages a) and b) have occurred a certain number of times in a defined period of time, in order to avoid repetitive glare, it is proposed to perform additionally, equally chained sequentially, the steps: d) lighten or darken, depending on the starting darkness level of the mirror, up to an intermediate level said electrochromic mirror, e) detect the incidence on said mirror of a further luminous signal with a light intensity above a predetermined threshold, preset, representative of a further glare, f) darkening to a maximum level of darkness, from said intermediate level, said electrochromic mirror after said detection, to dampen said subsequent glare, and g) returning to said intermediate level of darkness said electrochromic mirror, after the cessation of the incidence of said subsequent light signal. Step d), along with those that follow it in sequential and chained ways, can begin both after a step b), in which case the mirror will be cleared to that intermediate level, as after a step c), in which case what will be done is to darken the mirror to that intermediate level.

For a preferred embodiment, the method comprises the following additional step: h) return said electrochromic mirror back to said minimum level of darkness, after a first predetermined time period without incident of a light signal, said sequential stages d) to g) ending in chains. Both in said step c) and in said step g) the possibility is contemplated that they, one or both of them, take place not immediately after said cessation of the incidence of the light signal, but after a second and a third. predetermined periods of time, respectively, after said cessation, said second and third predetermined periods of time being the same or different depending on the example of embodiment. Preferably said maximum level of darkness is a function of the light intensity and the duration of said incident light signal, causing said glare, and of the external ambient light. The invention also concerns, in a second aspect, to an electrochromic system applicable to a rear-view mirror of a motor vehicle, of the type comprising: - at least one electrochromic mirror as said rear-view mirror, - at least one first light sensor for monitoring the ambient light surrounding the rear-view mirror, - at least a second light sensor for monitoring the incident light on the electrochromic rearview mirror, at least one control unit of said electrochromic rear-view mirror, associated with said first and second light sensors, said control unit being adapted to control the electrochromic mirror according to the method proposed by the invention, in its first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features and advantages of the invention will appear more clearly from the following description of an example of embodiment, illustrated in the attached drawings and which must be taken as an illustration and not as a limitation. In said drawings: Fig. 1 is a graphic representation that reflects the behavior, against a condition of glare that is repeated over time, of an electrochromic mirror controlled by the "conventional decision making algorithm" representative of the state of the Technique, Fig. 2 is a graphical representation that reflects the behavior, in front of a condition of glare that is repeated in time, of an electrochromic mirror controlled by the method proposed by the present invention, and Fig. 3 shows graphically, in an enlarged and comparative manner, the behavior, in front of a glare condition, of a conventionally controlled electrochromic mirror (indicated in the graph as "standard dimming) and of an electrochromic mirror controlled by the method proposed by the present invention (indicated in the graph as "predictive dimming").

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS A method is proposed that implements an improved decision-making algorithm to greatly improve the final functionality of the electrochromic rear-view mirror. The key point is based on the fact that the proposed method can recognize situations where continuous glare occurs, as for example on roads with high traffic density, secondary roads with many curves with vehicles circulating behind the one that incorporates the electrochromic mirror, and many others. The present invention concerns, in a first aspect, a control method of an electrochromic mirror, applicable to a rear view mirror of a motor vehicle, whose basic operation can be seen in Fig. 2. The method comprises first the following sequential stages, which are already known in the state of the art, and in particular contemplated by the "conventional decision-making algorithm" explained above: a) detecting the incidence on said mirror of a light signal with a light intensity above a certain threshold , preset, capable of causing the mirror to darken to a maximum level of darkness, predetermined, said signal being representative of a glare and represented in the attached figures with broken line and referred to as "glare condition", b) darkening to said level maximum darkness (indicated in the figures as minimum reflectance), prefixed, said electrochromic mirror after at least one of said detections, to deal with said glare, and c) clarifying, after the cessation of the incidence of said luminous signal, to a minimum level of darkness said electrochromic mirror (indicated in the graphs as maximum reflectance), facilitating the vision of the outside of the vehicle, As already said said stages a), b) and c) are representative of the traditional way of controlling an electrochromic mirror in front of a condition of glare, in this case repeated over time. That is why they can be observed both in Fig. 1 (which reflects the state of the art), where said condition of glare is repeated four times, as in part of Fig. 2, specifically in the indicated area A in the same (where said condition is repeated five times), in which, for the sake of clarity, the representation of the graph relative to the glare condition has been obviated and only the one relating to the reflectance of the electrochromic mirror is represented. said condition / s. What really characterizes the method proposed by the present invention is that when at least the conventional steps a) and b) have occurred a certain number of times (five in the embodiment example shown in Fig. 2) in a defined period of time, in order to avoid repetitive glare, it is proposed to carry out a series of additional stages, equally chained sequentially. In other words when it is detected that the glare condition is repetitive, it is deduced, or predicted, that it is very likely to continue repeating, that is to say that there are new light signals striking the mirror and generating new glare, and therefore the mirror in a way more appropriate to the circumstances that are, and are expected to continue, suffering. For the example of embodiment illustrated in Fig. 2, the additional steps proposed are carried out after a step b) and are the following (the result of its realization in the mirror is indicated in zone B of Fig. 2): d ) to clarify up to an intermediate level said electrochromic mirror, e) detect the incidence on said mirror of a further luminous signal with a light intensity above a certain threshold, preset, representative of a further glare, f) darken to a maximum level of darkness, from said intermediate level, said electrochromic mirror after said detection, and g) returning to said intermediate level of darkness said electrochromic mirror, after the cessation of the incidence of said subsequent luminous signal. For another embodiment (not shown) said step d) could begin after a step c), in which case instead of clearing the mirror would darken to the commented intermediate level. For the preferred embodiment example shown in Fig. 2, the proposed method also comprises (see zone C of the Fig. 2): h) return said electrochromic mirror back to said minimum level of darkness, after a predetermined first period of time without incident of said light signal, said sequential stages d) to g) ending in chains. Zone D of Fig. 2 refers to the behavior of the electrochromic mirror in a conventional manner, analyzed through reflectance, after a subsequent and specific glare condition, that is, to those defined above steps a), b) and e), and represents the cessation of the use of the additional stages d) to h), and the return to the conventional control mode. For other examples of embodiment, not shown, both in said step c) and in said step g) the possibility is contemplated that they, one or both of them, are they produce not immediately after said cessation of the incidence of the light signal, but after a second and a third predetermined time periods, respectively, after said cessation, said second and third predetermined periods of time being the same or different depending on the example of embodiment .

To highlight, on the other hand, that said maximum level of darkness is a function of the light intensity and the duration of said incident light signal, provoking said glare, and of the external ambient light, as well as that the reflectance is expressed, in the figures attached in% but in base 1, according to the following fraction: Reflected light Reflectance = Incident light An important advantage resulting from the use of the method proposed by the present invention can be seen in FIG. 3, where it can be seen, in an enlarged and comparative manner, the behavior, against a glare condition, of an electrochromic mirror controlled in a conventional manner (indicated in the graph as "standard dimming) and of an electrochromic mirror controlled by the method proposed by the present invention (indicated in the graph as" predictive dimming "). It is observed that the time in which the electrochromic mirror reaches a level of Z reflectance that achieves negligible glare (indicated as "effective glare limit" in Fig. 3) is very lower using the proposed method, than the one that needs to reach the same level Z if the "conventional decision making algorithm" is used. This means that the time in which the driver is exposed to an annoying glare level is considerably reduced, generally in more than one second. This behavior greatly decreases the visual fatigue of the driver because when a new glare condition occurs, the amount of light reflected to the eyes of the driver is much less than when the mirror is rinsed to the minimum level mentioned (stage c)) . The invention also concerns, in a second aspect, an electrochromic system (not shown) applicable to a rear-view mirror of a motor vehicle, of the type comprising: - at least one electrochromic mirror as said rear-view mirror, - at least one first sensor of light to monitor the ambient light surrounding the rear view mirror, - at least a second light sensor to monitor the incident light on the electrochromic rear-view mirror, at least one control unit of said electrochromic mirror, associated with said first and second light sensors, said control unit being adapted to control the electrochromic mirror according to the method proposed by the first aspect of the invention. A person skilled in the art could introduce changes and modifications in the described embodiment example without departing from the scope of the invention as defined in the appended claims.

Claims (8)

Claims

1. - Control method of an electrochromic mirror, applicable to a rear-view mirror of a motor vehicle, of the type comprising the following sequential, chained steps: a) detecting the incidence on said mirror of a light signal with a light intensity above one determined threshold, preset, b) darken to a predetermined maximum level of darkness, said electrochromic mirror after at least one detection, and, c) clarify, upon cessation of the incidence of said light signal, to a minimum level of darkness said electrochromic mirror, facilitating the view of the outside of the vehicle, characterized in that when, at least stages a) and b) have occurred a determined number of times, in a defined period of time, to avoid a repetitive glare, it comprises performing, equally sequentially linked, the stages: d) lighten or darken to an intermediate level said electrochromic mirror, e) detect the incidence on said mirror of a further luminous signal with a light intensity above a certain threshold, preset, f) darkening to a maximum level of darkness, from said intermediate level, said electrochromic mirror after said detection, and g) returning said electrochromic mirror to said intermediate level of darkness, after the cessation of the incidence of said subsequent luminous signal.

2. Method according to claim 1, characterized in that it further comprises: h) returning said electrochromic mirror to said minimum level of darkness, after a first predetermined period of time without incident of a light signal, said sequential stages d) ag) ending in chained .

3. Method according to claim 1, characterized in that said step c) occurs after a second predetermined time period after said cessation of the incidence of the light signal.

4. - Method according to claim 3, characterized in that said step g) occurs after a third predetermined period of time after said cessation of the incidence of the subsequent light signal.

5. - Method according to claim 4, characterized in that said second and third predetermined time periods are equal.

6. - Method according to claim 4, characterized in that said second and third predetermined periods of time, are different.

7. - Method according to claim 1, characterized in that said maximum level of darkness is a function of the light intensity and the duration of said incident light signal, provoking said glare, and of the external ambient light.

8. - Electrochromic system applicable to a rear view mirror of a motor vehicle, of the type comprising: - at least one electrochromic mirror as said rear view mirror, - at least one first light sensor for monitoring the ambient light surrounding the rear view mirror, - at least one second light sensor for monitoring the incident light on the electrochromic rear view mirror, minus a control unit of said electrochromic mirror, associated with said first and second light sensors, characterized in that said control unit is adapted to control the electrochromic mirror according to the method of claim 1.