Digital electrochromic circuit with a vehicle network

#This invention relates generally to vehicle rearview mirror systems and, more particularly, to digital electrochromic rearview mirror systems.

#Digital electrochromic mirror systems are described in commonly assigned U.S. Pat. No. 6,089,721 entitled DIGITAL ELECTROCHROMIC MIRROR SYSTEM and U.S. Pat. No. 6,056,410 entitled DIGITAL ELECTROCHROMIC MIRROR SYSTEM, the disclosures of which are hereby incorporated herein by reference. Such systems are capable of controlling the reflectance level of an electrochromic element from the output of a microcomputer.

#Various forms of vehicle communication systems have been developed including wired networks, or busses, operating one of several known protocols. These include a LIN (Local Interconnect Network), a LAN (Local Area Network), a CAN (Car or Controlled Area Network), and the like. An advantage of such vehicle networks is that the wire harness to the mirror can be minimized to as few as three wires or so, yet provide a variety of functions. Wireless communication networks utilizing radio frequency and/or infrared communication for vehicles have also been proposed, such as those utilizing the BLUETOOTH protocol. Such wireless communication and the BLUETOOTH protocol are described in more detail in commonly assigned U.S. patent application Ser. No. 09/793,002, filed Feb. 26, 2001, entitled VIDEO MIRROR SYSTEMS INCORPORATING AN ACCESSORY MODULE, now U.S. Pat. No. 6,690,268, the disclosure of which is hereby incorporated herein by reference.

#FIG. 1 is a top plan view of a vehicle having a vehicular rearview mirror system, according to the invention;

#FIG. 2 is an electronic block diagram of a digital electrochromic mirror system, according to the invention; and

#FIG. 3 is an electronic block diagram of a vehicular rearview mirror system, according to the invention.

#Referring now specifically to the drawings, and the illustrative embodiments depicted therein, a vehicular rearview mirror system 10 is illustrated with a vehicle 11 and includes an interior rearview mirror assembly 16 and one or more exterior rearview mirror assemblies, such as driver side exterior rearview mirror assembly 12 and/or passenger side exterior rearview mirror assembly 14 (FIG. 1). Interior rearview mirror assembly 16 includes a digital electrochromic mirror system 18 which is preferably supplied according to the principles disclosed in commonly assigned U.S. Pat. Nos. 6,089,721 and 6,056,410, the disclosures of which are hereby incorporated herein by reference. Although the particulars of the invention are illustrated with an interior rearview mirror assembly 16, it should be understood that the principles of the invention could be equally applied to either or both exterior rearview mirror assemblies 12, 14.

#Digital electrochromic mirror system 18 includes a microcontroller 20 and an electrochromic mirror reflective element 22. As is disclosed in the '721 and '410 patents, microcontroller 20 receives inputs from light sensors 24 (preferably phototransistors or photodiodes) and supplies digital outputs 26a, 26b which control solid-state switches 28a, 28b in order to provide a drive signal at 30 thereby establishing a partial reflectance level of electrochromic reflective element 22. Microcontroller 20 includes a microprocessor.

#Digital electrochromic mirror system 18 further includes a bus interface 32 which interfaces with a vehicle network, or bus, 34. Items on network 34 can be connected by wired or wireless connection. Wired connection may include wire, cables, fiber-optic cables, and the like. Wireless connection can be by infrared (IR) or radio-frequency (RF) communication, and, preferably, may be a short-range RF interconnection using the BLUETOOTH protocol. Vehicle network, or bus, 34 may utilize various buss protocols including a Local Internet Network (LIN), a Local Area Network (LAN), a Car (a/k/a Controlled) Area Network (CAN), or other vehicle network protocol. The BLUETOOTH protocol is a low-cost, low-power radio-based cable replacement or wireless link based on short-range radio-based technology. BLUETOOTH enables creation of a short-range (typically 30 feet or so, although longer and shorter ranges are possible), wireless personal area network via small radio transmitters built into various devices. For example, transmission can be on a 2.45 gigahertz band, moving data at about 721 kilobits per second, or faster. In the illustrated embodiment, network 34 is a multi-drop bus which requires three or fewer wires for communication between a plurality of other vehicle functions 36, as illustrated in FIG. 3. In situations where timing and power consumption system constraints may cause network 34 wakeup time to be too slow for an automobile maker system response requirement, suitable adjustments may be made in the architecture of network 34. The network may be configured as disclosed in commonly assigned U.S. patent application Ser. No. 09/341,450 filed Jul. 8, 1999, by Drummond et al. for a VEHICLE REARVIEW MIRROR AND A VEHICLE CONTROL SYSTEM INCORPORATING SUCH MIRROR, now U.S. Pat. No. 6,291,905, the disclosure of which is hereby incorporated herein by reference.