EP0785882A1

EP0785882A1 - Multiplexed windshield wiper control interface system and method

Info

Publication number: EP0785882A1
Application number: EP95938789A
Authority: EP
Inventors: Donald L. Mueller; Richard E. Wainwright
Original assignee: ITT Automotive Electrical Systems Inc
Current assignee: Valeo Electrical Systems Inc
Priority date: 1994-10-13
Filing date: 1995-10-06
Publication date: 1997-07-30
Also published as: KR970706148A; WO1996011823A1; JPH10507427A

Abstract

A vehicle window wiper interfacing system and method for interconnecting a plurality of components, for example a rain sensor (13), wiper control switch (26), wiper controller (36), in a window wiper circuit is shown. Each of the components, (e.g. 13, 26, 36) in the circuit may generate a component signal corresponding to one or more component states, for example rain sensor sensitivity or wiper mode of operation, etc. The interfacing system and method generates a single component signal for each component. The component signal is capable of representing one or more of a plurality of component states, depending on the component and the multiplexing waveform chosen to represent the states for that component. Component signals are generated for each of the components (e.g. 13, 26, 36) and subsequently simultaneously communicated over two or even one communication path (e.g. MUX1 - MUX4) to a receiving component.

Description

MULTIPLEXED WINDSHIELD WIPER CONTROL INTERFACE

SYSTEM AND METHOD

Field of the Invention This invention relates to a vehicle window wiper control interfacing arrangement, and more particularly, to a system and method for interfacing a wiper controller, a rain sensor, and a user switch in a multiplexed interfaced arrangement which facilitates reducing the number of communication paths required when transmitting component state information among the components.

Background of the Invention In the field of windshield wiper controls, it has become common to provide a rain sensor, a user wiper control switch, and a wiper system controller for controlling the operation of the wiper motor and wiper blades. Typically, the various components of the system need to communicate or receive various types of state information from one or more other components in the system. By way of example, the information regarding the wiper switch position selected by the user is required by the rain sensor and system controller. Likewise, wiper arm blade position information is also required by the sensor from the controller. Also, a wipe mode request as well as diagnostic information must be communicated from the rain sensor to the controller.

Each component usually has a plurality of different states, any one of which may be communicated to a receiving component. One arrangement for interfacing the various components is to provide separate input and output communication paths for each component state. However, there are incremental costs and design disadvantages associated with providing such separate paths, and there is also reduced circuitry reliability associated with using multiple communication paths.

What is needed, therefore, is a low cost and reliable arrangement for providing an interface which utilizes a limited number of interface or communication paths and which is still capable of accommodating the communication requirements required by the various components and their associated component states.

Summary of the Invention A primary object of the present invention is to provide a multiplex interfacing arrangement which permits input and output component state information to be communicated across a small number of communication paths. Another object of the present invention is to provide an improved interfacing arrangement which utilizes a plurality of different multiplexing techniques, including analog multiplexing, time division multiplexing and duty-cycle multiplexing. Another object of the invention is to provide a design which is relatively low in cost and reliable and which reduces the need for providing multiple dedicated data lines for each state information item associated with each component. In one aspect of this invention, there is provided a method for controlling communication among a plurality of components in a circuit for use in an automobile wherein each of said plurality of components comprise a plurality of states, the method comprising the steps of generating a component signal for each of the plurality of components; the component signal corresponding to at least one of the plurality of states for that component; and simultaneously transmitting each component signal across a communication network in the circuit.

In another aspect of the invention there is provided a communication network for use in an automobile; a plurality of components, each of the plurality of components having a plurality of states and being capable of generating an associated component signal corresponding to at least one of the plurality of states; and a multiplexor coupling each of the plurality of components for permitting simultaneous communication of the signals.

In still another aspect of the invention there is provided a method for communicating between a first component and a second component in a wiper circuit in an automobile; the method comprising the steps of coding a first component signal for the first component and a second component signal for the second component, the first and second component signals generally corresponding to at least one state associated with the first or second component, respectively; transmitting each of the first and second component signals across a signal communication path to the second and first component signals, respectively; and causing the first and second component signals to be decoded by the second and first components, respectively.

An advantage of this circuit and method is that it provides means for communicating component state information from a component to another component via a single path. Another advantage is that this circuit and method facilitates reducing manufacturing costs associated with some circuit designs of the path.

These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawing, and the appended claims.

Brief Description of the Drawing Fig. 1 is a diagram of a window wiper system of the present invention;

Fig. 2 is a diagram showing a wiper controller and a plurality of multiplexing paths, namely MUX1-MUX4;

Fig. 3 is an illustration showing the modulation of a component signal from a sensor to the wiper controller on communication path MUX3; and Fig. 4 is an illustration showing the modulation of a component signal from a wiper controller to a rain sensor on communication path MUX4.

Description of the Preferred Embodiment

Fig. 1 illustrates a system having a windshield 10 being wiped by a pair of wipers 12, 14 driven by a motor 16 powered by a motor drive unit 20. Motor 16 is a dual speed motor and is activated by a controller 24 shown in phantom lines. Controller 24 functions in response to switching signals generated by a wiper switch 26 and a rain sensor 13 which are received at an input port 32. The controller transmits actuation commands to drive unit 20 via an output port 34. While a variety of switch arrangements are contemplated, the switch 26 comprises a five-position sliding switch 26a and a sliding or rotary switch 26b (not shown) which will be described for purposes of illustrating an embodiment of the invention. Switch 26b has five manually selectable switching positions indicated by the legends #1 - #5. These switching positions enable an operator to select any one of five rain sensor sensitivity levels. Switch 26 may provide switching selections such as MIST, OFF, AUTO, LOW and HIGH, all as illustrated in Fig. 1.

Switching signals provided to controller 24 via input port 32 are processed by a wiper controller 36. As described in detail in co-pending application Serial No. (Docket ITT 005 P2), which is incorporated by reference and made a part hereof, an operator may obtain a desired rain sensor 13 sensitivity level during wiping. In order to achieve this, the operator first selects the AUTO position for switch 26a. The sliding or rotary switch 26b is then set to one of five illustrated positions #1 - #5. Switch 26b generates a switch 26 component signal in the form of an analog voltage corresponding to the switch 26a and 26b setting. As shown in the wiper circuit in Fig. 2, the controller 36 includes an A/D converter 62 (Fig. 2) which converts the analog voltage to a digital value.

In accordance with the present invention, the wiper controller 36 maintains all necessary communications with switch 26, as well as with a wash switch 41 , a wash pump or motor 33 and the rain sensor 13.

Preferably, eight lines labelled MUX1 - MUX4, HIGH, B+ or IGNITION, GND and PUMP are employed in the system 8. The functions of the B+ or IGNITION and GND lines are self evident. The PUMP line activates wash pump 33, and the HIGH line carries a signal indicating that the operator wants a high speed wipe and has set switch 26 at the HIGH position. The multiplexing lines MUX1 - MUX4 provide a communication path between the components to which they are connected. For example, the communication path MUX4 provides a multiplexing communication path between controller 36 and the rain sensor 13 (Fig. 1). The functions or states communicated by MUX1 - MUX4 are summarized in the following TABLES I and II.

TABLE I

Switch 13 States Controller 36 States Switches 26 and 28 —> Controller 36 Controller 36 > Sensor 13

Mux1 Mux2 Mux4

Vs Rs Vs Rs T1/T2 T3/T4

MIST Ign OΩ Ign 24Ω 74% 30% *

OFF open open 10% 30% *

AUTO - Sensitivity #1 Ign 680KΩ Ign 24KΩ 20% 30% *

- Sensitivity #2 Ign 270KΩ Ign 24KΩ 30% 30% *

- Sensitivity #3 Ign 150KΩ Ign 24KΩ 41% 30% *

- Sensitivity #4 Ign 82KΩ Ign 24KΩ 52% 30% *

- Sensitivity #5 Ign 39KΩ Ign 24KΩ 63% 30% *

LOW Ign 0Ω Ign 24KΩ 74% 30% *

HI Ign on Ign 24KΩ 74% 30% *

WASH don't care Ign 0Ω 85% 30% *

§ Inwipe Position - - 52%

@ Park Position - - 74%

Diagnostic Mode 1 - - 10%

Diagnostic Mode 2 - - 20%

•when not at inwipe

Notice that the five sensitivity positions #1

- #5 correspond to the various positions of switch 28 shown in Fig. 1.

TABLE II

Sensor States

Sensor Mode Sensor 13 —> Controller 36 Mux3 Duty Cycle

Off 9.1%

Internal Fault Detected 18.2% Glass Attachment Fault Detected 27.3%

No Input Data Present 36.4%

Rain Detected 45.4%

Low Speed Request 63.6%

High Speed Request 72.7%

Thus, note that switches 26a and 26b, controller 36 and sensor 13 each have an associated plurality of different component states which provide, for example, status or response information regarding that particular component. In the embodiment being described, only one state (or one set of states in the case of MUX4) is communicated over its respective communication path.

For example, when switch 26a is set at the AUTO position, MUX1 carries a component voltage signal indicating the setting of switch 26b. This controls the rain sensor 13 sensitivity. MUX1 may also provide a communication path for indicating the ignition voltage component signal or no voltage component signal at all, depending upon the setting of switch 26a. As illustrated in Table I, MUX1 utilizes analog multiplexing to carry information indicating 1 of 7 possible states associated with switches 26a and 26b of switch 26.

Likewise, MUX2 carries information indicating 1 of 3 switching different states associated with switches 26a and 26b. In the embodiment being described, the low state in Table I indicates that the ignition is switched off, and the high state indicates that the ignition is switched on and WASH switch 41 is closed. The intermediate state indicates that the ignition is switched on and WASH switch 41 is open.

Referring now to Tables I and II, MUX3 and MUX4 handle the communication of component states between rain sensor 13 and controller 24. As shown in Fig. 2, rain sensor 13 comprises an input circuit 13a and an output circuit 13b, each having suitable transistors, diodes and resistors configured as shown. Likewise, controller 24 (shown in Fig. 2 without input and output ports 32 and 34 for ease of illustration) has an input circuit 36a and an output circuit 36b having suitable transistors, A/D converter 62, diodes and resistors configured as shown. The input and output circuits 13a, 13b, 36a and 34b generate and receive their respective pulse width modulated signals MUX3 and MUX4 of the type illustrated in Figs. 3 and 4, respectively. For example, MUX3 utilizes duty cycle multiplexing and carries component state information signal from rain sensor 13 to controller 36. As shown in Table II and as discussed earlier herein, one of seven different component information states may be signalled. These seven states report various rain conditions and/or rain sensory 13 modes or even a wiper speed suggestion or request. Thus, for example, a "glass attachment fault detected" state may be generated by the rain sensor 13 and a corresponding component signal communicated, via MUX3, to controller 36, whereupon it is decoded by input circuit 36a and used by controller 36. Notice also that input circuit 36a also receives component signals from switch 26 on MUX1 and MUX2.

Referring to Fig. 3, it is seen that the corresponding component signal on MUX3 has a duty cycle period T punctuated by pulses of duration t which may be varied to correspond to any one of the seven states.

MUX4 utilizes two-channel, time division multiplexing similar to that used in U.S. Patent No. 5,200,676 which is incorporated herein by reference and made a part hereof. As suggested by Table I, MUX4 carries information regarding a plurality of controller 36 states from controller 36 to rain sensor 13. In the embodiment being described, dual information regarding two controller 36 states is provided. Consequently, the invention provides for modulation of the widths of two consecutive pulses. In this embodiment, the dual information includes wiper position information supplied by an inner wipe switch 70 and a park switch 72. As illustrated in Fig. 2, the state of these switches 70 and 72 is sensed by controller 36. It will be noted that switches 70, 72, and controller 36 may be integral to the wiper motor/controller.

Fig. 4 illustrates the modulation of the controller 36 component signal on MUX4. As shown therein, a pulse cycle is divided into two pulse periods t₂, t₄ which may have durations of about 4 milliseconds and 6 milliseconds, respectively, in the embodiment being described. Their corresponding pulse widths are t- and t₃. The two pulses are separately modulated to provide the duty cycle states indicated in TABLE I. Controller 36 is programmed for t₃ and t₄ in order to correspond to each switch 70, 72 setting, whereby generating the required two-channel, time division cycle waveform illustrated in Fig. 4. One suitable rain sensor 13 component for use in the embodiment of this invention is the water drop sensor disclosed and described in U.S. Patent No. 5,340,936 which is herein incorporated by reference and made a part hereof. Likewise, a suitable controller 36 may be the controller shown and described in U.S. Patent No. 5,200,676 referred to above.

A method for controlling communication among a plurality of components, such as rain sensor 13, switches 26a and 26b and controller 36 will now be described.

After the system 8 is configured as generally shown in Figs. 1 and 2, the various states for each of the modes illustrated in Tables I and II are determined and programmed or configured in their respective units rain sensor 13, controller 36 and/or switch circuit 27 (Fig. 1).

During operation, a rain sensor component signal, a switch component signal and a controller component signal for each of the rain sensor 13, switches 26a and 26b, and controller 36 components, respectively, is generated by an appropriate signal generator, such as switch generator 26c, sensor generator 13c and wiper generator 36c, resident in each component. In this regard, it should be appreciated that each component signal corresponds to one state in the case of the rain sensor 13 (MUX3) and switches 26a and 26b (MUX1 and MUX2) and two states in the case of controller 36 (MUX4).

Notice that the rain sensor component signal and controller component signal are duty cycle multiplex signals which may take the form shown in Figs. 3 and 4, respectively. Thus, the sensor signal generator and associated output circuit 13b may generate a dual-cycle signal of the type shown in Fig. 3. As illustrated relative to Fig. 4 and described above, the controller generator 36c and associated output circuit 36b may generate a multi-cycle signal which is capable of representing the two or more states. Advantageously, the network or interface configured by MUX4 permits communications of any pair of states associated with controller 36 by utilizing the multiplexing signal generating approach described herein.

Once component signals representing the states for each component are generated or coded, they are communicated or transmitted over a communication interface or network MUX1 - MUX4. Thus, the switch signals associated with switches 26a and 26b, sensor signal from sensor 13 are communicated over paths MUX1 , MUX2 and MUX3, respectively. Notice also that the controller component signal is communicated over a single path MUX4.

It should be appreciated that the various component signals generated may be communicated over their respective multiplex lines MUX1-MUX4 continuously and/or simultaneously. Also, receiving components (such as rain sensor 13 and controller 36) not only utilize their respective signal generators 13c and 36c and output circuits 13b and 36b to code or generate their respective component signals comprising high and low waveforms, but these components also utilize their input circuits 13a and 36a to decode component signals received from other components into high and low states for subsequent interpretation and/or processing.

Advantageously, the invention provides a multiplexing interfacing arrangement which permits input and output state information for one or more states selected from a plurality of states of one or more components to be communicated to an associated component across two or even one communication path.

While the forms of the device herein described constitute the preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of device, and that changes may be made without departing from the scope of the invention which is defined in the appended claims.

Claims

CLAIMS :

1. A method for controlling communication among a plurality of components in a circuit for use in an automobile wherein each of said plurality of components comprise a plurality of states, said method comprising the steps of: generating a component signal for each of said plurality of components; said component signal corresponding to at least one of said plurality of states for that component; and simultaneously transmitting each component signal across a communication network in said circuit.

2. The method as recited in claim 1 wherein said transmitting step comprises the step of: transmitting each component signal across a communication network having less than two signal lines coupled to any one of said plurality of components together.

3. The method as recited in claim 1 wherein said generating step further comprises the step of: generating at least one multi-cycled component signal simultaneously representing at least two of said plurality of states for any one of said plurality of components.

4. The method as recited in claim 3 wherein said generating step comprises the step of generating a dual- cycle component signal representing two states for one of said plurality of components.

5. The method as recited in claim 2 wherein said transmitting step comprises the step of: connecting said plurality of components together using a communication network having only one signal path coupled to each of said plurality of components.

6. The method as recited in claim 1 wherein said method comprises the step of: providing a plurality of components selected from the group consisting essentially of: a rain sensor, a wiper switch, or a wiper controller.

7. The method as recited in claim 1 wherein said generating step comprises the step of: selecting a multiplexing waveform to represent said component signal.

8. The method as recited in claim 1 wherein said generating step comprises the step of: selecting a multiplexing waveform to represent the component signal generated by each of said plurality of components.

9. The method as recited in claim 8 wherein said waveform comprises a duty cycle of (tpw)/τ where 5 msec < T < 10 msec and tpw < T.

10. A communication network for use in an automobile; a plurality of components, each of said plurality of components having a plurality of states and being capable of generating an associated component signal corresponding to at least one of said plurality of states; and a multiplexor coupling each of said plurality of components for permitting simultaneous communication of said signals.

11. The communication network as recited in claim 10 wherein said multiplexor comprises not more that two communication paths connected to each of said plurality of components.

12. The communication network as recited in claim 10 wherein said plurality of components comprises at least one rain sensor.

13. The communication network as recited in claim 12 wherein said plurality of components further comprises at least one controller.

14. The communication network as recited in claim 10 wherein each of said plurality of components comprises: a signal generator for generating said component signal.

15. The communication network as recited in claim

14 wherein said signal generator is capable of generating a multi-cycle signal corresponding to a plurality of states.

16. The communication network as recited in claim 10 wherein at least one of said plurality of states corresponds to a position of a wiper on a windshield.

17. The communication network as recited in claim 10 wherein at least one of said plurality of states corresponds to a wiper switch position.

18. The communication network as recited in claim 14 wherein said signal generator is capable of generating a component signal comprises a predetermined waveform comprising a duty cycle of (tpw)/τ where 5 msec < T < 10 msec and tpw < T.

19. The communication network as recited in claim 18 wherein said predetermined waveform is multicycle to correspond to the number of plurality of states represented by said component signal.

20. A method for communicating between a first component and a second component in a wiper circuit in an automobile; said method comprising the steps of: coding a first component signal for said first component and a second component signal for said second component, said first and second component signals generally corresponding to at least one state associated with said first or second component, respectively; transmitting each of said first and second component signals across a single communication path to said second and first component signals, respectively; and causing said first and second component signals to be decoded by said second and first components, respectively.