GB2315899A

GB2315899A - Vehicle driver inactivity detector

Info

Publication number: GB2315899A
Application number: GB9715421A
Authority: GB
Inventors: John Nigel Adams
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-08-01
Filing date: 1997-07-22
Publication date: 1998-02-11
Anticipated expiration: 2017-07-22
Also published as: GB9715421D0; GB2315899B

Abstract

An infra-red transmitter / detector system for detecting the lack of movement of a vehicle steering wheel, featuring a compact small angle segment reflector 3 mounted in a radial plane on the boss of the steering wheel, with system de-activation when the reflector segment moves out of of the field of view of the detector 11, 13.

Description

VEHICLE DRIVER INACTIVITY DETECTOR This invention relates to a detector for vehicle driver inactivity.

An alert driver of a vehicle will normally make numerous small corrective movements of the steering wheel about or near the straight ahead position whilst driving along essentially straight motorways and long uninterrupted roads. At any onset of drowsiness, a driver will cease to make these corrective movements. There are several known systems that detect the absence of these normal small corrective movements and activate an alarm. One such system is a non-contact one using a photo-electric transmitter / receiver and a circumferential strip of reflective / non-reflective bands around the steering wheel boss. However, in practice this circumferential strip system has several limitations / undesirable features. Amongst these are: That it allows nuisance warnings when extended bends are negotiated, where the steering wheel is held in an essentially still position several degrees away from the straight ahead position; that modern vehicles tend to have short depth non-circular steering wheel bosses where it is not practicable to fit a circumferential band; that the circumferential strip has to be customised to fit different vehicles, precluding a single design for universal installation; that the striped band is visible to the driver and occupants of the vehicle, and can be perceived as not in keeping with the decor of the vehicle's steering console.

According to this invention proposal, an infra-red transmitter / detector and reflector system for sensing the lack of movement of a vehicle steering wheel features a compact small angle segment reflector mounted in a radial plane on the boss of the steering wheel, with system de-activation when the reflector segment moves out of the field of view of the detector.

The small angle segment reflector subtends an angle sufficient to accomodate the normal corrections of a steering wheel made by a driver about or near the straight ahead position. Means is provided to deactivate the system whenever the small angle segment reflector moves out of the field of view of the transmitter / receiver unit, since this positioning of the steering wheel in itself requires a force to be applied and indicates an alert driver. This deactivation of the system may be achieved for example through a mechanical switch within the transmitter / detector unit that detects the presence of the small angle segment reflector, or through a unique reflective stripe pattern code at each end of it, or through a second dedicated infra-red transmitter / detector sensing a second reflective track mounted on the small angle segment reflector. The small angle segment reflector's radial plane design is such that it enables a universal mounting through attachment to the forward surface of the steering wheel boss. The small angle segment reflector mounting position on the steering wheel boss is such that the active striped face of the reflecting pattern is towards the front of the vehicle and not normally visible to the driver or occupants of the vehicle. Further, the compact small angle segment reflector may usually be placed such that it is concealed behind a steering wheel spoke, providing a neat inconspicuous installation. A further development of the design would be to attach the small angle segment reflector to the forward facing surface of a steering wheel spoke.

An additional benefit of the design is that the small angle segment reflector mounted in a radial plane achieves a greater sensitivity of steering wheel movement detection by reason of its longer effective operating radius beyond that of the steering wheel boss.

Alternatively, all aspects of the above described infra-red transmitter / receiver and reflector design could similarly be achieved using a magnetic pick-up coil and a small angle segment reflector pattern formed from magnetic material.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows in perspective, the relative positions of the electronic unit1 the small angle segment reflector, the steering wheel boss, and the steering column housing.

Figure 2 shows a simplified plan view section through the steering column.

Figure 3 shows the small angle segment reflector.

Figure 4 shows the strip magnet attached to the small angle segment reflector.

Figure 5 illustrates the infra-red beam path.

Figure 6 shows the block diagram of the electronic circuit.

Referring to the drawing, the general layout is shown in Fig 1, where the electronic unit 1 is shown mounted on the fixed steering column housing 2 of the steering column, and the small angle segment reflector 3 is shown attached to the front face of the rotating boss 4 of the steering column. Fig 2 shows a section through the vehicle's steering wheel 5, steering column 6, and steering column housing 2. The electronic unit 1 houses an infra-red (IR) transmitter / receiver, electronic circuit, and alarm, and is mounted on the side of the fixed steering column housing using adhesive backed mating Velcro pads 7 to enable both adjustment and simple attachment / detachment. The small angle segment reflector 3 is mounted on the front face of the boss 4 of the steering wheel, using double sided adhesive tape 8, such that as the steering wheel rotates, the reflecting / non-reflecting stripes of the reflector alternatively reflect / absorb the beam from the IR transmitter as the stripes cut across the beam. When the beam is reflected by a segment, it is received by the IR receiver. In this way an alternating output signal is generated by the IR receiver, the signal frequency being dependent upon the angular velocity of the steering wheel. The small angle segment reflector 3 is shown in Fig 3. The detected presence of the small angle segment reflector within the field of view of the detector is achieved by a reed switch / permanent magnet system. The reed switch is mounted within the sensor unit, immediately adjacent to the IR transmitter / detector electronic component. A permanent magnet strip 9 is shown in Fig. 4 attached to the back surface of the small angle segment 3.

This strip's magnetic field actuates the reed switch whilst the small angle segment is within the immediate field of view of the detector, which switch is used to complete an activating circuit within the electronic unit. Conversely, when the small angle segment is outside the field of view of the detector, the reed switch opens and the circuit is deactivated. A detail of the electronic unit and reflector is shown in Fig 5, where the transmitted beam 10 from the IR transmitter 11 is shown striking a reflective stripe of the small angle segment reflector and being directed back as a reflected beam 12 to the IR receiver 13.

The electronic circuit is powered from the vehicle's electrical power supply or a self contained battery, and contains all the circuitry necessary to operate the IR transmitter, process the signals received from the IR receiver, and output a signal to the audible alarm.

Fig. 6 shows the general arrangement of such an electronic circuit, including the IR transmitter 11. The signal from the IR receiver 13 is amplified by a variable gain amplifier 14, which amplified signal causes a reset or partial reset of the variable timer circuit 15. Activation / deactivation of the circuit is effected by circuit 16, which contains the reed switch. The time delay of the variable timer circuit may be adjusted by the vehicle driver through a variable control to suit the steering mechanism characteristics of the particular vehicle, the road surface, and the driving conditions. The output from the timer circuit is fed to a signal level detector 17 which gives an output drive to the audible alarm 18 when a preset value of signal level is sensed.

Claims

1. A detector system for sensing the lack of movement of a vehicle steering wheel, featuring a compact small angle interactive segment mounted in a radial plane on the boss of the steering wheel, with system deactivation when the passive interactive segment moves out of the field of view of the detector.

2. An infra-red transmitter I detector and reflector system for sensing the lack of movement of a vehicle steering wheel, featuring a compact small angle segment reflector mounted in a radial plane on the boss of the steering wheel, with system deactivation when the reflector segment moves out of the field of view of the detector.

3. A compact small angle segment reflector substantially as described herein with reference to Figures 1-6 of the accompanying drawing.

3. An infra-red transmitter / detector and reflector system for sensing the lack of movement of a vehicle steering wheel, featuring a compact small angle segment reflector mounted in a radial plane on the boss of the steering wheel.

4. An infra-red transmitter I detector and reflector system for sensing the lack of movement of a vehicle steering wheel, with system deactivation when the reflector segment moves out of the field of view of the detector.

5. An electronic detector substantially as described herein with reference to Figures 1-6 of the accompanying drawing.

Amendments to the claims have been filed as follows CLAIMS 1. A compact small angle interactive segment mounted in a radial plane on the boss of the steering wheel, forming part of a detector system for sensing the lack of movement of a vehicle steering wheel.

2. A compact small angle segment reflector mounted in a radial plane on the boss of the steering wheel, forming part of an infra-red transmitter I detector and reflector system for sensing the lack of movement of a vehicle steering wheel.