EP0513061A1

EP0513061A1 - Distance indicator

Info

Publication number: EP0513061A1
Application number: EP19910902725
Authority: EP
Inventors: Michael Westmoreland
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-01-18
Filing date: 1991-01-18
Publication date: 1992-11-19
Also published as: GB2240075A; GB9001154D0; AU7057591A; WO1991010878A1

Abstract

L'indicateur comprend un boîtier (2) ou autre élément supportant un disque (20) conçu pour projeter un couple de lignes (24, 25) sur le pare-brise d'un véhicule à des positions à espacement vertical pour indiquer les distances d'arrêt minimum pour certaines vitesses. Les lignes peuvent être réglées à l'horizontale par rotation du disque (20) autour d'un axe droit et les positions verticales des lignes sont pré-réglables par coulissement du boîtier (2) en avant et en arrière sur une base fixe (1). Un couvercle mobile (28) est prévu pour occulter l'une ou l'autre des lignes projetées ou les deux.The indicator comprises a housing (2) or other element supporting a disc (20) designed to project a pair of lines (24, 25) on the windshield of a vehicle at vertically spaced positions to indicate the distances d '' minimum stop for certain speeds. The lines can be adjusted horizontally by rotation of the disc (20) around a straight axis and the vertical positions of the lines are pre-adjustable by sliding the housing (2) forwards and backwards on a fixed base (1 ). A movable cover (28) is provided to conceal one or the other of the projected lines or both.

Description

DISTANCE INDICATOR

TECHNICAL FIELD OF THE INVENTION

This invention relates to a distance indicator for motor land vehicles.

BACKGROUND

Every year, thousands of people are killed, maimed or injured in road traffic accidents. Many of these accidents are preventable, being, in the main, due to driver error rather than mechanical defect.

Poor weather conditions significantly contribute to these accidents through drivers failing to appreciate changes in road surface conditions and visibility. After the occurrence of such accidents it is very common to hear a Police spokesman say "Visibility was down to 25 yards; Drivers were travelling too fast, too close". This applies particularly to motorways. Because of the character of motorway driving, drivers are lulled into a false sense of security and fail to appreciate the dangers, particularly failing to appreciate the minimum safe distance between vehicles relative to their speed. Moreover, everyones perception of speed and distance differs, and what may appear to be safe to one person may in fact be highly dangerous. Although shortest stopping distances are published in various sources these may only be memorised prior to a driving test and then forgotten.

It has been proposed in United Kingdom Patents No.s 1 259 110, 1 261 232 and 1 355 041 and in Unites States Patent No. 3 603 929, to project indicator marks onto the windscreen of a vehicle to indicate the width of a vehicle in front. The idea is that as the vehicles move together the vehicle in front will appear wider. Thus, if the perceived width of the preceding vehicle exceeds the indicated safe width the driver will know that he is probably too close. However, the main drawback of such an arrangement is that the actual width of vehicles can vary considerably, (consider a motorbike and a lorry for example), so this proposal is highly inaccurate.

A more accurate system is proposed in United Kingdom Patent No. 1 336 062 and United States Patent No. 3 469 234. This system takes advantage of the observation that as the spacing between vehicles becomes less the preceding vehicle will appear to be lower in the drivers field of vision. Thus, by projecting a horizontal line onto the windscreen at a height corresponding to the minimum safe spacing for a given speed, the driver will know that if he is travelling at that speed and the vehicle in front appears to be below this line, the vehicles are too close.

In this latter US Patent No. 3 469 234 the device includes a tray-like body which supports image forming means comprising a transparent plate which is illuminated by a light source, such that a bar of light is projected from the edge of the plate onto the windscreen of the vehicle. The plate is arranged to be rotated about a generally horizontal axis to adjust the height of the image on the windscreen in accordance with the speed of the vehicle, and the tray is mounted for adjustment in a front-rear direction for adjustment of the datum position of the image.

This earlier proposal has several shortcomings. For example, the device is not suitable for an accessory for use with any make of vehicle. The device must also be accurately installed. It has, for example, been determined that the accuracy of such a device is dependent upon the cursor line being accurately aligned with the horizontal .

An object of the present invention is to provide a form of distance indicator device which is suitable for use in most, if not all current makes of vehicle and which is capable of giving accurate results even when it has initially been installed inaccurately.

SUMMARY OF THE INVENTION

The present invention proposes a distance indicator device which is characterised in that the image forming means is rotatable relative to the body about an axis which is generally upright in use of the device such that the cursor line can be adjusted to a horizontal position on the windscreen.

The image forming means is preferably arranged to project at least one further cursor line onto the windscreen at a different level to the first cursor line, and the image forming means includes adjustable

SUBSTITUTE SHEET cover means for selecting one of the cursor lines to be projected. In addition, the cover means is preferably movable to a shut-off position in which no cursor lines are projected onto the windscreen. Preferably the cover means is rotatable about a generally upright axis, which may be common to the axis of rotation of the image forming means.

The device preferably includes a base for attachment to the vehicle, the body being slidably mounted on the base enabling the vertical position of the cursor line to be adjusted on the windscreen to accommodate different drivers, and position indicator means are provided to enable the body to be reset to a predetermined position relative to the base.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is exemplified in the accompanying drawings, in which:

Figure 1 is a perspective view of a first distance indicator device of the invention,

Figure 2 is a longitudinal vertical section through the indicator device of Fig. 1,

Figure 3 shows the indicator device installed in a vehicle,

Figure 4 shows an image which the device produces on the windscreen at its lower speed setting, Figure 5 shows the image produced at its higher speed setting,

Figure 6 is a perspective view of a second indicator device of the invention, and

Figure 7 is an exploded side view of the device of Fig. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig.s 1 and 2, the distance indicator device comprises a base 1 and a housing 2 which is mounted on the base.

The base 1 includes a substantially flat rectangular baseplate 3 having inturned flanges 4 and 5 overlaying its two longer edges.

The housing 2 is also of substantially rectangular shape and includes a top wall 7, front and rear walls 8 and 9, and opposite side walls 10 and 11. A pair of outwardly projecting flanges 14 and 15 extend along the lower edges of the side walls 10 and 11 to locate beneath the inturned flanges 4 and 5 of the base, so that the housing is slidably adjustable relative to the base in a front-rear direction A. A scale 16 provided on one of the side walls 11 allows the position of the housing 2 to be accurately set relative to a marker 17 on the base flange 5.

Referring specifically to Fig. 2, a disc 20 is mounted for rotation about an upright axis on the top wall 7 towards the rear of the housing 2 by means of a depending circular wall 21 which locates in a circular aperture 22 in the top wall 7. The rotatable disc 20 contains a pair of spaced parallel image forming slots 24 and 25, the rearmost of which is in two longitudinally spaced halves 24a, 24b (Fig. 1). When viewed in transverse section as in Fig. 2, both slots have upwardly divergent walls. The two slots are surrounded by a rectangular frame 26 which is secured to the upper face of the rotatable disc 20 and which includes an inturned lip 27. This frame holds captive a slidable cover 28 which can be moved in a front-rear direction to cover either of the slots 24 or 25 leaving the other uncovered. A diffuser plate for light is secured to the underside of the disc 20 covering the two slots 24 and 25.

The housing 2 contains a filament lamp 30 or other light source, which receives electrical power via a cable 31 (Fig. 1) or from electrical cells (not shown) contained within the housing 2. A brightness control 32 for the lamp 30 is mounted in the side of the housing.

As shown in Fig. 3, the device is mounted on top of the dashboard 35 of a motor-driven land vehicle between the driver D and the windscreen 36. The base 1 may be secured to the dashboard by bolts, releasable catches, pressure-sensitive adhesive pads or other convenient means, with its front wall 8 directed towards the windscreen 36.

With the front slot 25 uncovered by the cover 28 the lamp 30 projects a slot-shaped beam of light onto the front windscreen 36 which is in turn reflected to the driver D. Although a single image is projected onto the screen this will be reflected from both the front and rear surfaces of the screen so that the driver will perceive a double image in the form of two parallel lines, as shown in Fig. 4. Most windscreens are curved horizontally, but by rotating the disc 20 the lines can be adjusted to a horizontal position. By sliding the housing back and forth the vertical position of the image can be moved up and down the windscreen, and moving the cover to uncover the broken slot 24 will instead cause a pair of double parallel lines to be projected higher up the screen, as shown in Fig. 5. In order to form a sharp image it has been found desirable that at least the rear wall of each slot should be inclined as shown in Fig. 2. The diffuser plate has also been found to be an advantage since it prevents a sharp image of the lamp from being seen on the windscreen.

To calibrate the device, the driver first marks out a position 23 metres (75 feet) in front of the vehicle, this being the overall stopping distance for a vehicle travelling at 30 mph. Having positioned himself correctly in a normal driving position the driver moves the cover to the rearward position and rotates the disc 20 to bring the double line image in the windscreen to horizontal. He then adjusts the housing back and forth until the image appears to lie on the road at the 23 meter marker and notes the reading on the scale 16. This reading may differ from driver to driver but each driver can quickly reset the device to his own position before driving away. The spacing between the slots 24 and 25 is such that by moving the cover 28 to cover the front slot 25 a broken pair of parallel lines are displayed at a higher position on the windscreen to indicate the correct distance for a speed 20mph above the initial setting, e.g. 30mph and 50mph.

Fig. 4 shows the view which the driver will get when following a car with the indicator set to 30mph. If the bottom of the car appears to be below the lines the driver is too close, assuming that the cars are travelling at about 30mph. If the speed of the cars increases to about 50mph the indicator will be reset to the second position as in Fig. 5.

The brightness control 32 enables the intensity of the image to be reduced in low ambient light conditions.

Larger numbers of slots could be provided enabling the device to be used over a wider range of speeds.

The distance indicator device of Fig.s 6 and 7 is less expensive to produce and easier to install than that just described. The device comprises a base 101, a slide 102, and an image forming disc 120. The device is formed predominantly of black plastics material, although other darkly coloured materials could be used.

The base 101 generally comprises a substantially flat rectangular plate 103 having a pair of inturned flanges 104 overlaying its two longer edges. A pad 141 (Fig. 7) which comprises a multiplicity of loops is secured to the bottom of the base 101, and a separate pad 142 which comprises a multiplicity of hooks is provided for

SUBSTITUTE SHEET engagement with the pad 141. (The hooks and loops could of course be transposed.) The pad 142 has a layer of pressure sensitive adhesive 143, which is normally protected by a peelable backing layer 144.

Referring back to Fig. 6, the slide 102 is also rectangular and includes a pair of outwardly projecting flanges 114 which locate beneath the flanges 104 of the base so that the slide can be adjusted relative to the base in a front-rear direction A¹. The slide is provided with an aperture 117 which overlies a series of differently coloured areas of the base so that as the slide 102 is moved relative to the base 101 different colours are displayed through the aperture 117. Thus, by adjusting the slide until the appropriate colour appears in the aperture 117 the position of the slide can be repeatedly accurately reset relative to the base.

The disc 120 is mounted at the front end of the slide 102 by a pin 121 such that the disc is rotatable about the axis of the pin, which extends perpendicular to the slide 102. The disc 120 is provided with a pair of spaced parallel image forming lines 124 and 125, one of which is in two longitudinally spaced halves 124a, 124b. The lines 124 and 125 are formed by light coloured reflective areas of the disc 120. A cover disc 128 is also mounted on pin 121 above the disc 120 for rotation about the axis of pin 121, and has a cut¬ out 128' equal to about one quarter of the disc. The cover disc can be rotated to three positions, in two of which the disc 128 covers one of the lines 124 or 125 leaving the other uncovered. In its third position the cover disc covers both of the lines.

SUBSTITUTE SHEET As indicated in Fig. 7, the lower surface of cover disc 128 is provided with a friction layer 148 of felt for example. The lower surface of disc 120 is provided with a similar friction layer 149, as is the opposed surface 150 of the slide 102. Thus, the frictional engagement of the disc 120 with the slide 102 is greater than that of the cover disc 128 with the disc 120, so that the disc 120 tends to remain in position as the cover disc is rotated.

The device is mounted on the dashboard of a motor vehicle by means of the adhesive layer 143, but it can be removed if required be releasing the mutual engagement of the pads 141 and 142. Since the lines 124 and 125 are brighter than the black background of the device they are reflected in the windscreen of the vehicle. By rotating the disc 120 the image in the windscreen can be adjusted to horizontal, and by adjusting the slide back and forth the vertical position of the image can be moved up and down the windscreen to calibrate the device, as described above i n rel ation to Fig. 1.

The two lines 124 and 125 again provide two different speed settings which can be selected by the cover disc 128.

Claims

1. A distance indicator device for use in a motor land vehicle for indicating a safe stopping distance to the eye of a driver thereof, the vehicle having a windscreen located in front of the driver, and the device comprising a body (2; 102), and image forming means (20, 24; 120, 124) mounted on the body for projecting a cursor line onto the windscreen in such a position that the line provides the driver with an indication of the distance between the vehicle and a vehicle in front, characterised in that the image forming means (20, 24; 120, 124) is rotatable relative to the body (2; 102) about an axis which is generally upright in use of the device such that the cursor line can be adjusted to a horizontal position on the windscreen.

2. A device according to Claim 1, in which the image forming means (20, 24; 120, 124) is arranged to project at least one further cursor line (25; 125) onto the windscreen at a different level to the first cursor line, and the image forming means includes adjustable cover means (28; 128) for selecting one of the cursor lines to be projected.

3. A device according to Claim 2, in which the cover means (28; 128) is movable to a shut-off position in which no cursor lines are projected onto the windscreen.

4. A devi ce accord i ng to Cl a i m 2 or Cl a i m 3 , i n

SUBSTITUTE SHEET which the cover means (128) is rotatable about a generally upright axis.

5. A device according to Claim 1, including a base (1; 101) for attachment to the vehicle, the body (2; 102) being slidably mounted on the base enabling the vertical position of the cursor line to be adjusted on the windscreen, and position indicator means (16, 17; 117) are provided to enable the body to be reset to a predetermined position relative to the base.

SUBSTITUTE SHEET