GB2270950A

GB2270950A - Optical combination lock

Info

Publication number: GB2270950A
Application number: GB9220536A
Authority: GB
Inventors: Michael John Arthur Turner
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-09-29
Filing date: 1992-09-29
Publication date: 1994-03-30
Also published as: GB9220536D0

Abstract

A combination look, has a cradle 6 supporting numbered thumbwheels 1, 2, 3 with apertures 9 that are aligned only when the code number is set, so that light from the LED 4 is detected by the photocell 5. A second set of apertures can be provided for a reset code. In place of the LED and photocell, optical fibres can be used to conduct the light. <IMAGE>

Description

OPTICAL COMBINATION LOCK This invention relates to an optical combination lock.

Combination locks are well known devices, one type comprising a row of numbered thumbwheels, each of which operates a switch when the code number is set.

Switches are not entirely suitable for certain environments, because of the possibility of electrical arcing and inductive effects. The contacts must also be protected from dust and moisture.

The invention provides an optical combination lock comprising a cradle supporting two or more numbered thumbwheels, sharing a common axis and having apertures made in relation to chosen code numbers, so that a beam of light may pass through all the thumbwheels only when the chosen code number is set.

Apertures may also be made on a different radius corresponding to another number, usually all zero, to allow the lock to be reset or to detect if the lock is being operated. A light source and photocell are usually attached to the lock, but may be remote and optical fibres used to conduct the light.

Optical fibres may also be introduced into the apertures of the thumbwheels to reduce light losses.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which : Figure 1 shows the combination lock with light source and photocell in position; Figure 2 shows the side view of a thumbwheel removed from the assembly of figure 1; Figure 3 shows the lock using optical fibres; Figure 4 shows an exploded view of figure 3.

Referring to the drawing of Fig 1, the combination lock is comprised of three thumbwheels 1,2, and 3, each of which is able to rotate independently about a common axis. The thumbwheels are numbered 0 to 9. On each side of the lock and directly opposite are an LED 4 and a photocell 5. The assembly is supported by a cradle 6 with apertures 7 and 8. Light from the LED 4 can only reach the photocell 5 when the correct combination code is entered.

Apertures in the thumbwheels are then aligned and light strikes the photocell 5. Fig 2 is a side view of thumwheel 3 to show the position of it's light aperture 9.

To isolate the optical combination lock from electricity, optical fibres are used to feed the lock. This version can be made entirely of non-metallic materials and is illustrated in Fig 3. There are two light paths through the thumbwheels 10,11,12 shown here, one from input fibre 13 to output fibre 14, corresponding to "000" reset code and one from input fibre 15 to output fibre 16 corresponding to access code "517it in this case. A cover 17 provides light proofing and windows for the numerals.

In the exploded view of Fig 4, spacers 18 and 19 prevent one thumbwheel from turning the next. For the same reason, the axle 20 is fixed to the cradle 21 and does not itself rotate. A click-stop mechanism, (not shown), could be added to each thumbwheel for easier adjustment.

Claims

1 An optical combination lock comprising a cradle supporting two or more numbered thumbwheels, sharing a common axis and having apertures made in relation to chosen code numbers, so that a beam of light may pass through all the thumbwheels only when the chosen code number is set.

2 An optical combination lock as claimed in claim 1, wherein means are provided for accurate registration of the thumbwheels such as a clickstop mechanism.

3 An optical combination lock as claimed in claim 1 or claim 2, wherein a light source and photocell are incorporated into the lock.

4 An optical combination lock as claimed in claim 1 or claim 2, wherein optical fibres are used to coduct light to and from the lock.

5 An optical combination lock as claimed in any preceding claim, wherein the thumbwheels have two sets of apertures at different radii to allow for two code numbers to be used as access and reset.

6 An optical combination lock as claimed in any preceding claim, wherein sections of optical fibre are introduced into the thumbwheel apertures to reduce light losses.

7 An optical combination lock as claimed in any preceding claim, wherein a cover is used to provide windows for the numerals and to exclude ambient light.

8 An optical combination lock substantially as described herein with reference to figures 1-4 of the accompanying drawings.