System for controlling a vehicle window and the like
BACKGROUND OF THE INVENTION 
     The present invention relates to a vehicle-mounted control system for automatically closing a motor-driven window and the like in response to raindrops. 
     Conventional motor-driven window regulators are responsive to a manually operated switch. Automatic closure of a vehicle window is one of desired features of a motor vehicle. Reliable raindrop sensors are required to meet this demand. 
     U.S. Pat. No. 4,394,605 (invented by H. Terazawa and assigned to the same assignee as the present invention and titled &#34;Load Drive Control System&#34;) discloses a wiper control system which senses raindrops to automatically initiate wiper operation. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a control system which comprises first means for emitting a beam of radiation into a section of the windshield of a vehicle from the inner surface thereof at such an angle of incidence that the beam reflects off the outer surface of the windshield, second means for detecting and converting the reflected beam into a first signal, third means for comparing the first signal with a reference value to generate a second signal, and fourth means responsive to the second signal for closing a window of the vehicle. 
     The system further comprises manually operated switching means having first and second circuit conditions for opening and closing said window, respectively. According to a feature of the invention, the fourth means comprises a reversible motor for driving the window in closing and opening directions in response to the first and second circuit conditions, respectively, means for detecting when a current flowing through the motor is higher than a predetermined value to generate an output signal, first control means responsive to the second signal and to the first circuit condition for energizing the motor in the window closing direction and responsive to the output signal for de-energizing the motor, and second control means responsive to the second circuit condition for energizing the motor in the window opening direction and responsive to the output signal for de-energizing the motor. According to this feature, the window is automatically stopped as it moves in the closing direction if this movement is hampered by an elbow of the vehicle occupant to reduce the element of danger. 
     According to a further feature of the invention, the system includes a window-operated switch arranged to be operated when the window is fully closed to cut off the power circuit for power saving purpose. 
     According to a still further feature of the invention, an indicator is provided to alert the occupant when the window is moving. 
     The control system is preferably switched from automatic mode to manual mode by means of a manually operated switch to render the system to responsive exclusively to manual control. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be described in further detail with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of an automotive vehicle with a raindrop sensor shown mounted behind the windshield; 
     FIG. 2 is an illustration of a raindrop sensor incorporated in the control system of the invention; 
     FIG. 3 is a circuit diagram of a modulator associated with the raindrop sensor; 
     FIG. 4 is a circuit diagram of a receiver associated with the raindrop sensor; 
     FIG. 5 is a circuit diagram of a window control unit; and 
     FIG. 6 is an illustration of a wiper control circuit. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, a rain-drop sensor 10 is secured to the windshield of an automotive vehicle 100 having a pair of side windows 20 which are opened or closed by a manually operated crank handle and at least one of which is automatically closed in response to a signal derived from the raindrop sensor 10 in a manner as will be described. The raindrop sensor 10 is mounted on the inner side of a glass windshield 2. 
     As schematically illustrated in FIG. 2, the raindrop sensor 10 comprises a pair of transparent fixing members 3 and 4 attached to the inner surface 2a of the windshield 2. Each of the fixing members is preferably formed of the same material as the windshield 2 and has a surface normal to the direction of light passing therethrough. A light-emitting diode 1 is located adjacent the fixing member 3 to direct a beam of light pulses into the windshield 2 at an angle θ to the vertical which is greater than the critical angle θ 1  at which total reflection occurs between glass and air but smaller than the critical angle θ 2  at which total reflection occurs between glass and water. Typical values of θ 1  and θ 2  are 41.1° and 61.1°, respectively. The incident light is totally internally reflected on the outer surface 2b of the windshield and bounces back to the inner surface as it advances through a section of the windshield 2 to the other fixing member 4. A light sensitive member, or a photodiode 5, is mounted adjacent the fixing member 4 to generate a signal when it receives the light pulses. It will be seen therefore that if there is a raindrop as shown at 6 on the outer surface 2b of the windshield, the total reflection is lost at this particular portion and there is a corresponding reduction in the signal detected by the photodiode 5. 
     The light-emitting diode 1 is activated by a modulator circuit 30 shown in FIG. 3. This circuit comprises an oscillator formed by inverters a, b, c, resistors R4, R5 and a capacitor C1. The oscillator output is coupled by resistors R2, R3 to the base of a switching transistor TR1 having its collector-emitter path connected in series with the light-emitting diode 1 between ground and a voltabge supply terminal +V via a resistor R1. The frequency of the oscillator is determined so that the light pulses injected into the windshield may be clearly distinguished by the photodiode 5 from light rays emitted from environments such as street lights. 
     The output signal from the photodetector 5 is applied to a receiver circuit 40 shown in FIG. 4. The receiver comprises a current-to-voltage converter formed by an operational amplifier Q1a, a capacitor C1a and a resistor R1a, and a band-pass filter formed by capacitors C3a, C4a, C5a and coils L1a, L2a. The band-pass filter rejects the noise component of the voltage signal and passes the component representing the intensity-modulated light. The output of the band-pass filter is applied to an operational amplifier Q2a for linear amplification. Diodes D1a, D2a rectify the amplified signal and a capacitor C8a and a resistor R11a forms a smoothing circuit to convert the signal into a DC voltage which is amplified by a DC amplifier Q3a. Further included is an operational amplifier Q4a having its inverting input coupled to the output of DC amplifier Q3a and its noninverting input coupled to the tap of a variable resistor VR1. The amplifier Q4a acts as a comparator to compare the output of the raindrop indicating DC signal with a reference setting determined by the variable resistor VR1. 
     Under fine weather conditions, the transparent medium 10 provides total internal reflection, so that the rain-drop DC signal is higher than the reference setting and the comparator Q4a generates a low level output. Under rainy conditions, the total internal reflection is partially or completely lost and the DC signal reduces in proportion to the amount of raindrops to a level lower than the reference setting, so that the comparator Q4a switches to a high level output state. 
     The output of the receiver circuit 40 is applied to the input of a window control unit 50 shown in FIG. 5. The control circuit 50 includes a manually operated switch 7 having a pair of stationary contacts 7a, 7b and a moving contact arm 7c which normally remains disengaged from contact with either of the stationary contacts. This switch 7 is loated in an easily accessible position such as a vehicle door or the instrument panel to allow the vehicle occupant to manually override the automatic window control system. When the vehicle occupant desires to close the window 20, the contacts 7a and 7c are brought into contact to apply a voltage +B to a window-close circuit 60, and when he desires to open the window, the contacts 7b and 7c are brought into contact to apply the voltage =B to a window-open circuit 70. 
     The window 20 is driven by a window drive motor 8 of a reversible type having a normally closed temperature responsive switch 8a to de-energize the motor 8 when it is heated to an abnormally high temperature. The motor 8 has such a loading characteristic that it requires a current of a few amperes under light loads as when the window is moving up or down and a current of several tens of amperes under heavy loads as when the window is pressed against the frame in a fully open or closed position or when external force is exerted upon it while moving in either direction. The motor 8 is supplied with a current Ia when the window is raised or an opposite current Ib when the window is lowered, the currents Ia and Ib being supplied from the window-closing circuit 60 and the window-opening circuit 70, respectively. 
     The window-closing circuit 60 comprises a relay RL1 having associated contacts 9a, and a relay holding circuit formed by transistors TR1 and TR3. The coil of the relay RL1 is energized by a current which is supplied from the output of the receiver 40 through a diode D5 or energized by a current supplied through the manual switch 7 from the voltage source at +B. When this relay is energized so that the current Ia flows from the +B voltage source through the normally open contacts 9a, temperature responsive switch 8a, motor 8, the normally closed contacts 9b of the relay RL2 and a current sensing resistor R8 to ground. 
     The window-opening circuit 70 comprises a relay RL2 having contacts 9b and a relay holding circuit formed by transistors TR2 and TR4. The coil of window-opening relay RL2 is connected to the contact 7b of switch 7 to be energized by the voltage +B. The relay contacts 9a and 9b the window-closing and window-opening relays are operated so that they are mutually exclusively connected to the motor 8. 
     The resistor R8 has a resistance value of about 10 ohms to provide as small a dissipation of Joule&#39;s heat as possible by the current of substantial magnitude, but provides a voltage sufficient to be compared with reference voltages to be described hereinbelow. 
     The resistor R8 develops a voltage Vi proportional to the motor current and therefore indicates whether the window is moving or pressed against the window frame either in the fully open or fully closed position. The voltage Vi, after having been filtered through an RC noise filter formed by a resistor R9 and a capacitor C1, is applied to a window comparator including a pair of operational amplifiers Q1 and Q2. Specifically, the RC filter has such a time constant value that it introduces a delay time of a few hundreds milliseconds in response to a step change in voltage cross the resistor R8 to remove unwanted high frequency components which arises from external light. 
     High and low reference voltages V H  and V L  are provided by a series circuit of resistors R5, R6 and R7 connected between voltage terminal +B and ground. The operational amplifier Q1 compares the motor-current indicative voltage Vi with the higher reference V H  and generates a low level output when Vi is higher than V H  and switches to an open level state when Vi is lower than V H . On the other hand, the operational amplifier Q2 compares the voltage Vi with the lower reference V L  and generates a low level output when Vi is lower than V L  and switches to an open level state when Vi is higher than V L . Therefore, when the window is moving upward or downward, the window comparator is in an open level state. If a positive voltage is present at a circuit junction 61 between the coil of relay RL1 and transistor TR1, a current will flow through a resistor R1 and a diode D3 to the base of transistor TR3, thus turning it on. This in turn biases the transistor TR1 through a resistor R3 into conduction. By the turn-on of transistor TR1, the collector current of this transistor holds the relay RL1 energized once operated in response to the potential at the circuit junction 61. 
     On the other hand, if a positive potential is present at a circuit junction 71 between the coil of relay RL2 and transistor TR2, transistor TR4 is biased into conduction by a current passing through a resistor R2 and a diode D4, causing transistor TR4 to turn on to hold the relay RL2 energized once operated by the potential at the junction 71. Diodes D1 and D2 are provided to keep the circuits 60 and 70 from interferring with each other due to unwanted sneak currents. 
     The operation of the window control circuit 50 is as follows. The relay RL1 is energized when contacts 7a  and 7c are closed by the occupant or when the rain-drop signal is delivered from the receiver circuit 30, resulting in the closure of the contacts 9a to cause the motor 8 to drive the window in the closing direction. As it starts rotating, the motor draws a current of a few amperes and the resistor R8 develops a corresponding voltage which is compared by the window comparator (Q1, Q2). The output of window comparator at terminal A thus switches to an open level state, causing transistors TR3 and TR1 to turn on successively to hold the relay RL1. Therefore, the motor 8 keeps running even though the switch 7 is released. If the window movement is impeded by the occupant or when the window reaches the fully closed position, the motor load and its current increases to several tens of amperes. The voltage across the resistor R8 correspondingly increases, so that the window comparator switches to a low output state. When this occurs, diose D1 is forwardly biased and the potential at the base of transistor TR3 finds a low impedance path through the diode D1 to turn transistors TR3 and TR1 off, de-energizing relay RL1 and motor 8. 
     With the window being fully closed, the operation of switch 7 closing its contacts 7a and 7c applies the +B potential to the relay RL2 to energize the motor 8 in the downward or opening direction. The window comparator is switched to an open level and transistors TR4 and TR2 are turned on to hold the relay RL2. If the downward movement of the window is impeded by the occupant or when the window reaches the fully open position, the motor current increases to several tens of amperes, switching the window comparator to a low output state. As a result, the diode D2 becomes forwardly biased and the potential at the base of transistor TR4 finds a low impedance path through the diode D2. Transistors TR4 and TR2 are successively turned off to de-energize the relay RL2 and hence the motor 8. 
     Since the rain-drop signal is useless when the window remains closed, a disabling circuit is provided to remove power from the modulator circuit 30 and receiver circuit 40. This disabling circuit comprises a normally open pressure responsive switch 11 arranged to close its contacts when the window is fully closed, a relay RL3 and a resistor R13 all of which are connected in series between the terminal at +B voltage and ground. The disabling circuit is completed when the relay RL3 is operated in response to the window being closed and opens its first contacts S1 provided in a first power line which couples the +B potential through a terminal 85 to the modulator 30 and the receiver 40 and opens its second contacts S2 provided in a circuit coupled from the output of the window control circuit 50 to the window motor control circuit 60. 
     A manually operated auto-to-manual changeover switch MS having a pair of ganged contacts ms 1  and ms 2  is further provided in the power circuits just described to disable the automatic operation of the window control system and operate the window regulator in manual mode. 
     For purposes of visually indicating that the window is moving in either direction, an operational amplifier Q3 is provided having its noninverting input coupled to the output of the window comparator and its inverting input coupled to receive a reference potential derived from a junction between resistors R10 and R11 which are connected in series between the +B terminal and grund. When the window comparator is in an open level state during the window movement, the amplifier Q3 switches to a high output state to turn a light-emitting diode 12. 
     It is preferable that the raindrop sensor 10 be mounted within the wiping area of a windshield wiper 13, FIG. 1, and the wipers 13 and 14 are operated in response to the raindrop signal. Since the raindrops within the wiping area are cleared by the wiper, the portion of the windshield where the raindrop sensor is mounted is quickly dried up as soon as the rainfall ceases, so that the raindrop sensor instantly resumes its operation. Furthermore, it is preferable that once the window has been closed in response to a rain fall the power circuit of the window control system be turned off to prevent it from responding to the raindrop signal which is interrupted each time as the raindrops are cleared by the wiping action while permitting the wiper to remain responsive to it. 
     For this purpose, the circuit of FIG. 5 is modified as shown in FIG. 6. A wiper control circuit 80 is shown connected to the output of the comparator Q4a of the receiver circuit 40 to drive wiper motors 81 which in turn activate the wipers 13 and 14. The control circuit 80 is powered through a manually operated power switch 82 from a terminal 84 at +B potential. This potential is further coupled by through a second power line including a diode 83 to the power supply terminal 85 of the circuits 30 and 40. When it starts raining, the raindrop signal from the comparator Q4a operates the window control circuit 50 to close the window. Upon the full closure of the window, the pressure responsive switch 11 is operated to energize the relay RL3 to disconect the first power line of the circuits 30 and 40. However, the circuits 30 and 40 receive power through the diode 83 of the second power line to continue the raindrop signal to be supplied to the wiper control circuit 80. 
     The foregoing description shows only preferred embodiments of the present invention. Various modifications are apparent to those skilled in the art without departing from the scope of the present invention which is only limited by the appended claims. Therefore, the embodiments shown and described are only illustrative, not restrictive.