Exterior rearview mirror system

[00002] The present invention relates to automotive exterior rearview mirror systems that include adjustable driver and passenger side exterior mirrors.

[00003] Passenger automobiles today commonly include outside rearview mirrors on both the driver and passenger side of the vehicle. These mirrors are typically adjustable both vertically (up/down) and horizontally (left/right), using electric motors controlled by the driver via a mirror position switch. Usually, a single switch assembly is used which includes a joystick type switch for directing the two-directional movement of the motors as well as a left/right selector switch that switches between the two exterior mirrors so that they can be adjusted one at a time, independently of each other. The selector switch may also include a locked position so that movement of the joystick does not activate either of the mirror motors. On vehicles provided with memory positioning, the mirrors can be automatically moved by suitable vehicle circuitry to a preset position established by the driver. Such circuitry can be implemented using position sensors on the mirrors to determine the instantaneous position of the mirrors in both the horizontal and vertical directions. These types of mirror positioning circuits are well known.

[00004] Normally, the driver and passenger side exterior mirrors are adjusted individually by the driver, as mentioned above. However, it has been proposed to provide automatic adjustment of the passenger side exterior mirror based on positioning of the driver side mirror. It is a general object of this invention to provide an exterior rearview mirror system of this type in which adjustments made by the driver to the driver side exterior mirror can be detected and used to automatically make similar adjustments to the passenger side exterior mirror so as to provide the desired field of view through the passenger side mirror without requiring independent adjustment of the passenger side mirror by the driver.

[00005] In accordance with the invention, there is provided a method and apparatus for adjusting an automobile exterior rearview mirror system in which adjustments by the vehicle operator to the driver side mirror are used to make automatic adjustments to the passenger side mirror without requiring the operator to make separate, independent adjustment of the passenger side mirror. The automatic adjustment is determined using the horizontal angle of the driver side mirror along with distance data related to the position of an inboard edge of each of the exterior mirrors. The distance data preferably comprises two pieces of data; namely, (1) the distance along the vehicle's lateral (side-to-side) axis between the driver position and the inboard edge of the driver side mirror, and (2) the distance along the lateral axis between the driver position and the inboard edge of the passenger side mirror. These values along with the horizontal angle of the driver side mirror can be used geometrically to determine the proper positioning of the passenger side mirror.

[00013] FIG. 1 illustrates an exterior rearview mirror system 10 implemented on a typical passenger vehicle 12. To assist an occupant driver 14 in obtaining an exterior view to the rear of the vehicle, the mirror system 10 includes a left-hand, LH, rearview mirror assembly 16 and a right-hand, RH, rearview mirror assembly 18, each disposed on a respective exterior side of the automobile 12. Each mirror assembly 16, 18 has a reflective element such as a mirror 20, 22 having an angular position that is adjustable by a pair of positioning motors 24—one for horizontal positioning and the other for vertical positioning. The motors 24 for each outside rearview assembly 16, 18 are operated from within the vehicle by an occupant driver 14 via a mirror position switch assembly 26.

[00014] As shown in FIG. 2, the mirror position switch assembly 26 has a short joystick-type actuation arm or lever 28 that is both displaceable through a small arc in four directions (up, down, left, and right) and rotatable about its central axis between three positions (identified as LH/RH, neutral, and RH). When the switch lever 28 is rotated to the LH/RH mode position 30, pivotal movement of the lever 28 to any of its four positions will cause a concomitant change in the position of the LH mirror 20, and the system will automatically adjust the RH mirror 22 as well. The four directional positions can be identified by arrows 32 imprinted on the switch 26. Rotation of the lever 28 to a RH mode position 34 will enable the driver to adjust the RH mirror 22 directly, without effecting the LH mirror 20. In addition, the toggle 28 can be rotated to the neutral or locked position 36 where pivotal movement of the switch lever 28 will be ignored by the system. The LH/RH mode position 30 is disposed approximately thirty to ninety degrees counter-clockwise from the locked position 36 and the RH mode position 34 is orientated clockwise from lock position 36 by the same thirty to ninety degree angle. The switch assembly 26 can be implemented as two separate switches: a four-way mirror position switch having four sets of contacts (one for each direction); and a three position mirror select switch for selecting between the two mirror adjustment modes (LH/RH mode or RH-only mode) or putting the system in a locked condition. Of course, a variety of other switch configurations can be used for the rearview mirror system 10 such as where, for example, the mirror select switch function is separated from the lever 28 and implemented using a rocker switch, slide switch, or other independent switch. A simpler joystick type switch can then be used for the directional control. Regardless of which of these switch configurations may be used, their design, construction, and implementation within the vehicle as a part of the mirror positioning control circuit is well known to those skilled in the art.

[00015] Referring to FIG. 3, a block diagram of the control logic for the rearview mirror system 10 is illustrated. The circuitry can be active at all times and signals from the mirror position switch 40 are routed by the mirror select switch 42 to either a LH mirror controller 44, a RH mirror controller 46, or are blocked in the event the select switch 42 is in its locked position. When the occupant driver 14 selects the LH/RH mode position 30 for mirror control, any mirror position input signals received from the mirror position switch 40 are used by the LH mirror controller 44 to control operation of the left hand mirror's horizontal (left-right) and vertical (up-down) positioning motors 24. From the driver's perspective, this adjustment of the left-hand mirror using the illustrated embodiment need not be any different than is done for conventional exterior rearview mirror systems. Furthermore, there are any of a number of well known circuit designs available for using the mirror position input signals to provide corresponding adjustments of the left hand mirror using the motors 24.

[00016] The instantaneous position of the LH mirror 20 is detected using position sensors 48 and is provided as a feedback position data to a central control circuit 50. Using this data, the central controller 50 calculates the necessary position output signals for the RH mirror 22. This output signal is sent to the RH controller 46 which then utilizes its associated motors 24 to properly position the mirror 22. RH mirror assembly 18 also includes a set of position sensors 52 which instantaneously monitor the angular positioning of mirror 22 and provide feedback used by the RH controller 46 to determine when the mirror is properly positioned. These position sensors 48, 52 and their use for feedback in positioning the mirrors 20, 22 can be implemented using known circuit designs employed in memory mirror systems of the type in which a desired position of the mirror for a particular driver is stored in memory and can be recalled to automatically reposition the mirror to that driver's preferred position. Memory mirror systems of this type can also be integrated with other cockpit devices such as electronic seat positioning and adjustable pedal systems. In this regard, the control circuit 50 can be a separate circuit from the LH and RH mirror controllers 44, 46 or can be integrated in with either one or both of these, its function in this embodiment primarily being to utilize the LH mirror feedback position data from the position sensors 48 to determine the automatic adjustments needed to the RH mirror 22 to position it in the desired orientation.

[00017] Where the driver 14 desires to set the position of the RH mirror individually using the mirror position switch 40, the mirror selector switch 42 can be rotated instead to the RH position 34, which when operated, communicates with the RH controller 46 to adjust only the RH mirror 22. This mode effectively bypasses the central controller 50 altogether and does not actuate or effect the LH mirror 20.

[00018] Having thus described the overall design and operation of the rearview mirror system 10, the process utilized by the central controller 50 to automatically adjust the RH mirror 22 based on driver adjustments to the LH mirror 20 will now be described in conjunction with FIGS. 4 and 5. As indicated above, mirror positioning occurs along two orthogonally related planes—a horizontal plane for left-right angular adjustments and a vertical plane for upwardly and downwardly angular adjustments. The positioning adjustments for each mirror 20, 22 involve rotating the mirror through a horizontal and/or vertical angle about a pivot point, and these centers of rotation for mirrors 20 and 22 are identified as Points P and Q, respectively, in FIG. 5. In the illustrated embodiment, the vertical angle of both mirrors 20, 22 are maintained the same and this typically is desired for a driver under normal conditions. Thus, with the mirror select switch 42 in the LH/RH position, vertical adjustments commanded by the driver for the left mirror are used to move both mirrors 20, 22 to result in the same angle.

[00019] The relationship between the horizontal angular positions of the two mirrors is more complex and is shown in FIGS. 4 and 5. When applying these geometric relationships and making certain approximations, the central controller 50 can use an equation to calculate the desired RH mirror 22 horizontal angle β using only the measured LH mirror angle α and distance data concerning the position of an inboard edge (points A and E) of each of the two mirrors. The horizontal angle α is determined using the received feedback position data from the sensors 48. As will be understood from the discussion below, the distance data can be completely determined using only the measured LH mirror angle α along with predetermined data that is fixed for a particular vehicle model and can be preloaded by the manufacturer into the controller 50. In calculating the horizontal angle α, the relationship between the feedback position data and the associated horizontal angle can be provided in any desired form such as by an equation or as a look-up table. In this regard, determination of the horizontal angle need not involve any such conversion of the position data to a value measured in angular degrees, but rather the horizontal angle can be represented using any analog or digital value suitable for determining a passenger side mirror control signal that can be used along with the position sensors 52 to move the passenger side mirror to the proper corresponding position. Thus, in some embodiments, the directly measured data from the sensors 48 can be converted to a corresponding control signal for the passenger side mirror without transforming the measured data into an angular quantity.

[00020] As shown in FIG. 4, by applying the reflection principle of a mirror (i.e., {overscore (B′C′)} is {overscore (BC)}'s image viewed by the driver 14 from point O if {overscore (AD)}⊥{overscore (BB′)} and {overscore (AD)}⊥{overscore (CC′)}), the equations for the horizontal angle for both LH and RH mirrors 20, 22 are: $\begin{array}{cc}\alpha =\frac{1}{2}{\tan }^{-1}\left(\frac{r_{\mathrm{LH}}}{s_{\mathrm{LH}}}\right)\mathrm{and}& \left(1\right)\\ \beta =\frac{1}{2}{\tan }^{-1}\left(\frac{r_{\mathrm{RH}}}{s_{\mathrm{RH}}}\right)& \left(2\right)\end{array}$
where α and β are the horizontal angles of their respective mirrors 20, 22. Since s_LH≈s_RH≈s, replacing s_LH and s_RH with s and substituting equation (1) into equation (2), the horizontal angle of the mirror 22 for the RH assembly 18 can be approximated by the following equation where β is a function of α and the distances r_LH and r_RH along the vehicle's horizontal lateral (left-right) axis between the driver's position (Point O) and the inboard edges of both mirrors (Points A and E): $\begin{array}{cc}\beta =\frac{1}{2}{\tan }^{-1}\left(\frac{r_{\mathrm{RH}}}{r_{\mathrm{LH}}}\tan 2\alpha \right).& \left(3\right)\end{array}$

[00022] By inspection of FIG. 5, it can be seen that r_LH and r_RH vary depending upon the horizontally-rotated position of their respective mirror and that they can be determined based on the both the distance w between the driver's position O and the center of rotation P, Q of the mirror, and the distance t between the center of rotation P, Q and the inboard edge A, E of the mirror. Now, since t_LH≈t_RH, equation (3) may be further modified to: $\begin{array}{cc}\beta =\frac{1}{2}{\tan }^{-1}\left(\frac{w_{\mathrm{RH}}-t_{\mathrm{RH}}}{w_{\mathrm{LH}}-t_{\mathrm{LH}}}\tan 2\alpha \right)\approx \frac{1}{2}{\tan }^{-1}\left(\frac{w_{\mathrm{RH}}-t_{\mathrm{LH}}}{w_{\mathrm{LH}}-t_{\mathrm{LH}}}\tan 2\alpha \right)& \left(4\right)\end{array}$
where t_LH=νsin (α+τ) and ν denotes the distance from the mirror rotation center P to the inboard edge A of mirror 20. The angle τ is the angle formed between (i) a centerline C_L of the mirror and (ii) an edge line E_L that intersects the inboard edge of the mirror 20 and meets the centerline C_L at the center of rotation P. As will be appreciated, both ν and τ are mathematical constants that are fixed for a particular mirror assembly 16, as are the distances w_LH and w_RH for a particular vehicle design. Thus, equation (4) permits determination of the passenger side horizontal angle using only a single variable (α), with the other terms of the equation all being constants that are predetermined for a particular mirror system and vehicle model.

[00024] The validity of equation (4) has been mathematically and experimentally verified, as shown in FIG. 6. In this chart, the measured LH mirror angle is the horizontal angle α determined from the feedback position data. The measured RH mirror angle is the horizontal angle selected by the same driver using the RH mode of selector switch 42, and the calculated RH mirror angle is the horizontal angle β determined according to equation (4). These tests results showed only small differences between the measured and calculated RH angles. These differences are not entirely due to the approximations made in the equations above, but also reflect a fact that the RH mirror positions were determined to not have always been placed by the driver at their best positions. In some instances they were placed at positions judged “good enough” by the driver.

[00025] Since the only variable needed by equation (4) above is the information from the position sensors, the rearview mirror system 10 can thus be easily implemented using conventional memory mirror systems of the type that permit the driver to store one or more desired mirror positions which can be recalled later for automatic repositioning of the mirrors to the preset positions. The design and construction of such systems are known and come equipped with the position sensors 48, 52 to provide the necessary mirror position data for the feedback/control of the memory functionality of the mirrors. The simultaneous control of the LH and RH mirror assemblies that is carried out by controller 50 can be realized by modifying the existing control algorithm of the memory control module used in these types of memory systems. These and other suitable circuit designs are well within the level of skill in the art.

[00026] It will thus be apparent that there has been provided in accordance with the present invention an automobile exterior rearview mirror system which achieves the aims and advantages specified herein. It will of course be understood that the foregoing description is of a preferred exemplary embodiment of the invention and that the invention is not limited to the specific embodiment shown. Various changes and modifications will become apparent to those skilled in the art. For example, the illustrated embodiment is directed to the use of the system on an automobile designed for driving on the right side of a public road and it will be appreciated that the system can be implemented for vehicles in which the driver and front passenger positions are switched from that shown in the drawings, in which case the driver side mirror is the RH mirror and the passenger side mirror is the LH mirror. Furthermore, the automatic mirror adjustment technique described herein can also be used to control other rearview mirrors and systems, including, for example, an interior rearview mirror, one or more video cameras, periscope devices, etc. All such variations and modifications are intended to come within the scope of the appended claims.