GB2340320A - Movement measuring device; indicating the degree of vehicle braking - Google Patents

Description

2340320 Indicating Means The invention relates to a method by which the

amount of movement of an integer or component can be monitored and used to provide various outputs and in particular this invention relates to the application of this system for warning following vehicles that the vehicle in front has applied its brakes and also indicates the degree of braking.

Vehicles such as cars etc. have brake lights which come on when the brakes are applied so as to warn the following vehicles, such systems use the operation of a switch which is operated on the depression of a brake pedal or lever. Systems have been proposed in which the brightness of the brake light, or other means for indicating the degree of braking, depends on the severity of the depression of the brake pedal or lever.

is Another proposal has been to use the increase in hydraulic pressure as the brake pedal is depressed to control a means for indicating the degree of braking.

Equipment for indicating the degree of braking of a vehicle has been proposed in which a potentiometer is connected to a brake in the vehicle and when the brake is applied a current is sent by the potentiometer to the brake lights with the number of lights turned on being in proportion to the operation of the brake operating means.

As the degree of braking is controlled by the brake operating means the number of lights turned on will be in proportion to the degree of braking.

Equipment has also been proposed in which deceleration of the vehicle is detected and this controls lights at the rear of the vehicle.

However, existing equipment has not proved reliable in day to day use mainly due to the wear to the various components such as linkages etc. caused by prolonged use so that the base line for the braking drifts and there is lack of consistency. We have now devised equipment which detects the movement of a component and 35 can be used to indicate the degree of braking of a vehicle to following vehicles which equipment is robust and easy to install and operate.

According to the invention there is provided a movement measuring device which comprises a strip of substantially light reflective material which has a series of spaced apart substantially non light reflective lines formed on its surface, which strip is able to move past a light source and a light detecting and counting means whereby, when the light source operates and strip moves past the light detecting and counting means, light from the light source shines on the strip and the light detecting and counting means counts the number of lines which moves past light detecting and counting means and thus measures the distance of movement of the strip.

In use as a braking detection system the movement measuring device is adapted to be connected to a brake operating means in the vehicle and the movement measuring means is able to send a signal to a light operating means, the light operating means is being adapted to turn on light emitting diodes (LEDs), the number of LEDs turned on being in proportion to the operation of the brake operating means.

The brake operating means sends a signal to the light operating means and the strength of the signal is a measure of the movement of the brake operating means.

Thus the number of light emitting diodes turned on depends on the strength of the signal received by the light operating means from the brake operating means.

Preferably the signal is a digital signal so that the signal received by the light operating means is digitised and the number of LEDs to be turned on will be clearly ascertained by the light operating means and the system will be easy to operate.

Any part of the braking system can be used to operate the movement measuring means provided that the amount of movement of the braking system corresponds to the degree of braking. The movement measuring means can be connected directly or indirectly to any component or part of the braking system which moves as a brake pedal or lever is operated or depressed. Conveniently, with a foot brake it can be connected to the brake pedal or a strut, rod or lever connected to the brake pedal. In most vehicles the further the foot pedal is depressed the greater the degree of braking so that a device which responds to the amount of depression of the foot pedal can be 3 conveniently used.

In hand operated braking systems a hand lever etc. is moved and the amount of braking depends on the amount of movement of the lever so the movement of the lever can be used to operate the invention.

Optionally the system or device can also incorporate a switch which turns on the conventional brake lights which shows the brakes have been applied and this can replace the existing brake light operating switch. This switch can operate in such a way that it is on when there is no braking and turns off when there is braking and the turning off of the switch causes the brake light to come on, so has a "fail safe" characteristic.

Preferably the lines on the strip are all spaced apart at a known distance from each other and preferably are formed across the strip substantially at right angles to the direction of movement of the strip. Preferably the strip has parallel sides with the lines running perpendicularly across the strip.

Such strips are commercially available from PWB Ruhlatec GrnbH.

Suitable light detecting and counting means are commercially available from Hewlett Packard Limited and are used in applications such as scanners etc.

Light emitting diodes are widely available and can come in a variety of colours; in the present invention a preferred colour is red.

The number of LEDs is not critical, there must be at least three, but the total number will depend on the specific circumstances. The more LEDs there are the greater the ability to differentiate between the different degrees of braking, but the more the expense; nine to eleven has been found to be a convenient number.

The light operating means fimctions to turn on the LEDs and preferably is in the form of a silicon chip which operates in proportion to an input signal. Suitable chips are commercially available and easy to use and preferably are programmed or form part of a processor. This system requires no moving parts and is robust and reliable in use; the use of such chips or processors enables the preferred digital signal to be received. The processor can provide various output signals, either digital or analogue for control of various functions including brake lights, braking systems etc.

It is a feature of the invention that the output from the processor can also be used as an input for various control systems such as engine management systems so that, as the brake is depressed, the engine can automatically make any adjustments required to the engine operation. 10 Such an operation is only possible with the digital signal processed by the processor as used in the present invention. Alternatively an analogue system can also be sent out by the processor and used to input components of the vehicle Another feature of the invention is that the system is self calibrating i.e. when the vehicle is started and the brake pedal not engaged then, whatever the position of the strip and brake pedal, the system is automatically zero so that, when the brake pedal is depressed, the degree of braking is accurately indicated. With other systems relying on a potentiometer or rheostat there will inevitably be a zero error which will arise unpredictably from wear in the system etc. 20 As LEDs operate on a current of a few milliamps the system can easily be operated from the car battery or electrical system. The invention can be installed in the car when it is built or it can be retrofitted after 25 the car has been built and the invention also comprises the components of the invention adapted to be fitted to a vehicle. The system is easy to install and involves adding an attachment to a moving part of the braking system e.g. the brake pedal, and running wires to the light operating 30 means, which can be installed anywhere convenient, and then running wires from the light operating means to the LEDs. In one embodiment the light operating means forms part of a unit incorporating the LEDs in which case the installation is simplified. 35 The LEDs can be installed anywhere convenient on the rear of the vehicle and a preferred position is above or below then rear windscreen where they can easily be seen by following vehicles.

The invention is illustrated in the accompanying diagram which shows a circuit arrangement of the invention.

In the drawing a brake pedal (1) has a movement detector (2) attached to it and movement of the pedal (1) causes a signal to be sent from (2) to a control unit (3)), with the signal being a measure of the amount of movement of (1). The control unit (3) incorporates a programmable chip so that the output is digitised and accurately corresponds to the movement of (1); the control unit (3) can then send signals to other indicating or operating systems of the vehicle.

In the control unit (3) there is also a switch which operates when the pedal (1) moves to turn on conventional brake lights.

The unit (2) incorporates a strip of substantially light reflective material which has a series of spaced apart substantially non light reflective lines formed on its surface, which strip is able to move past a light source and a light detecting and counting means whereby, when the light source operates and strip moves past the light detecting and counting means, light from the light source shines on the strip and the light detecting and counting means counts the number of lines which moves past light detecting and counting means and thus measures the distance of movement of the strip.

The unit (2) sends a signal corresponding to the distance moved to the unit (3) which causes light emitting diodes (LEDs) (4) to be turned on, with the number of LEDs (4) turned on depending on the signal sent from (3), which will depend on the amount of movement of (1). The signal from (3) is also sent to the engine management system so that, as the brake is depressed, the engine management system automatically makes the appropriate adjustments to the engine operation.

Thus the number of LEDs (4) turned on will depend on the depression of brake pedal (1) and thus will indicate the degree of braking.

6

Claims (9)

Claims

1. A movement measuring device which comprises a strip of substantially light reflective material which has a series of spaced apart substantially non light reflective lines formed on its surface, which strip is able to move past a light source and a light detecting and counting means whereby, when the light source operates and strip moves past the light detecting and counting means, light from the light source shines on the strip and the light detecting and counting means counts the number of lines which moves past light detecting and counting means and thus measures the distance of movement of the strip.

2. Equipment for indicating the degree of braking of a vehicle, which equipment comprises a movement measuring device as claimed in claim I adapted to be connected to a brake operating means in the vehicle and in which the movement measuring device is able to send a signal to a light operating means, the light operating means being adapted to turn on LEDs, the number of LEDs turned on being in proportion to the operation of the brake operating means.

3. Equipment as claimed in claim 2 in which the brake operating means is a foot brake and the movement measuring device is connected to the brake pedal or a strut, rod or lever connected to the brake pedal

4. Equipment as claimed in any one of claims 2 to 3 in which there are from nine to eleven LEDs.

5. Equipment as claimed in any one of the preceding claims in which the signal is a digital signal so that the signal received by the light operating means is digitised.

6. Equipment as claimed in any one of the preceding claims in which the digitised signal is transmitted to a processor which operates or controls the light operating means.

7. Equipment as claimed in claim 6 in which the processor provides additional output 35 signals, either digital or analogue for control of vehicle functions.

8. Equipment as claimed in claim 7 in which the additional output signals control or provide an input for brake lights, braking systems or engine management systems.

9. Equipment for indicating the degree of braking of a vehicle as hereinbefore described with reference to the drawings.