GB2423828A

GB2423828A - Magnifying device with areas of different magnification

Info

Publication number: GB2423828A
Application number: GB0510539A
Authority: GB
Inventors: Peter John Charles Spurgeon
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-03-03
Filing date: 2005-05-24
Publication date: 2006-09-06
Also published as: GB0504448D0; GB0510539D0

Abstract

Refracting or reflective devices produce areas of different magnification when examining an object. A lens made from refractive material includes areas of differing magnification which adjoin each other with smooth transition.

Description

I 2423828 A Magnifying Device

Background

This invention relates to means for magnifying a drawing, text or an object.

Present devices include magnifying glasses Consisting of biconvex or piano convex spherical lenses made of a transparent material or shaving or make-up mirrors (concave magnifying mirrors). The devices are typically held by means of a frame and a handle or bracket or stand at a distance from the small print or object to be examined and the print or object under the central section is shown magnified, typically between two and 10 times linear magnification. Even in the case of a quality frameless device, Compensated for aberrations, viewing across the outer edge of the magnifier does not adjoin the unmagnified print, several words being omitted altogether until the device is m.oved. Magnifying lenses are often used by vision impaired persons for reading or for reading parts of a map. Magnifying mirrors cause lateral inversion causing print to be seen back to front'. As there is an area which cannot be seen - the area between the magnified and the unmagnified region - it makes it very difficult to maintain a realistic view of the way that the magnified section fits into the whole, where the magnified piece lies in relation to other features of the object.

Statement of Invention

The invention consists of a magnifying device having varying curvatures, some of the centres of curvature not lying on a principal axis. The invention preferably includes an inner area producing magnification and an outer area which does not magnify or distort. Curvatures and centres of curvature of the region between the inner and outer area are designed to produce varying magnifications or reductions such that there are smooth transitions of magnification across the entire viewing area.

An example of the device consists of a lens having one flat side whilst the other side is spherically convex for its centre portion, this forming constant undistorted magnification. Various curvatures outside this portion then form a smooth curve for each cross section whilst maintaining a radial symmetry. A portion of the outer edge of the lens is of constant thickness so that there is no magnification. This outer part of the lens again joins the smooth curve of the intermediate part of the lens. Since the inner portion is convex then some or all of the intermediate part must be concave in order that the final curved surface has its tangent coincident with that of the outer surface.

A further example of the device consists of a mirror which is spherically concave for its centre portion, this forming constant magnification with lateral inversion. Various curvatures outside this portion then form a smooth curve for each cross section whilst maintaining a radial symmetry. A portion of the outer edge of the mirror is plane, at right angles to the principle spherical axis of the central portion so that there is no magnification or reduction at this outer part. This outer part of the mirror again joins the smooth curve of the intermediate part of the mirror. Since the inner portion is concave then some or all of the intermediate part must be convex in order that the final curved surface has its tangent coincident with that of the outer surface. 2.

Advantages The magnifier can he centred on the desired area easily, because the immediately surrounding details remain visible. Wherever the magnifier is used no part of the area surrounding the magnified portion will be obscured. The user may not need to examine all the areas in the detail afforded by the central part of the magnifier because it will be obvious if the variably magnified part is not of interest. The magnifier could be used to examine a screen showing a moving image, enabling the user to easily track' a subject whilst still being aware of the scene as a whole, for example in use with a surveillance camera.

Introduction to Drawings

An example of the invention will now be described with reference to the accompanying drawings: Figure 1 shows a cross section of a mould to make a lens of varying magnification.

The curve includes a convex central portion with its centre on the axis of the lens and a concave portion whose centre is on the line at right angles to the outer plane portion.

If the surface of the mould is polished then it becomes a mirror with varying contiguous magnifications.

Figure 2 shows a cross section of a mould to make a lens of varying magnification.

The curve includes a convex central portion with its centre on the axis of the lens, a straight-line intermediate portion and a concave portion whose Centre is on the line at right angles to the outer plane portion. If the surface of the mould is polished then it becomes a mirror with varying contiguous magnifications.

Figure 3 shows a cross section of a mould to make a lens of varying magnification.

The curve includes a convex central portion with its centre on the axis of the lens, a further convex intermediate portion of larger radius whose centre is off the central axis and a concave portion whose centre is on the line at right angles to the outer plane portion. If the surface of the mould is polished then it becomes a mirror with varying contiguous magnifications.

Detailed Description

Figure 1 shows a cross section of a mould to make a lens of varying magnification.

If the surface of the mould is polished then it becomes a mirror with varying contiguous magnifications. Points on the cross section denote the areas of constant magnification CE and a concave area of varying magnification BC. The centre of curvature of the arc CE is on the principal axis. The centre of curvature of the arc BC is on the intersection of the radius through C and the right angle to the nonmagnification portion from B outwards. The fact that the tangent to a circle is at right angles to its radius means that the curves CE and BC meet smoothly and the non- magnification portion and BC meet smoothly. Thus all the smooth curves meet smoothly and the magnified image will be smooth in the transition part between B and C. Distortion is unavoidable but parts of the image will adjoin each other smoothly from the constant magnification region to the unmagnified region.

The curve includes a convex central portion with its centre on the axis of the lens, a straight-line intermediate portion and a concave portion whose centre is on the line at right angles to the outer plane portion. If the surface of the mould is polished then it becomes a mirror with varying contiguous magnifications. Here there is a straight line between the two curved sections. The lens made from this mould will be compared with that from the figure 1 mould to assist in the design of other lenses and mirrors.

The curve includes a convex central portion with its centre on the axis of the lens, a further convex intermediate portion of larger radius whose centre is off the central axis and a concave portion whose centre is on the line at right angles to the outer plane portion. If the surface of the mould is polished then it becomes a mirror with varying contiguous magnifications. Here the lens would have two Convex and one concave curved sections. The lens made from this mould will be compared with that from the figure 1 and figure 2 moulds to assist in the design of other lenses and mirrors.

The moulds could be used singly to produce pseudo piano-convex lenses, or in pairs to produce pseudo biconvex lenses. The lenses could be made from glass or clear plastic materials. Lenses could be of the Fresnel lens' type. Lenses could be machined or molded or ground and polished. Laser equipment could be used in the production process.

Whilst these examples are applied to a circular lens or mirror the same principles can be applied to any shape provided that each and every cross section is a smooth contiguous curve and that the outer area is nonmagnifying.

In the case of a mirror device the lateral inversion can be eliminated by using a first plane mirror and a second contiguous magnifying mirror, in the maimer of a periscope. It is not necessary that both mirrors should be held in the exact alignment and relative positions as in a periscope if one or both mirrors are of a sufficient size.

A lens according to the invention may be used in conjunction with mirrors so that viewing is possible in inaccessible places. Examples of this use would include inspection of parts of a mechanism or biological use.

A device according to the invention may be used in conjunction with other viewing devices such as cameras, telescopes, liquid crystal displays, microscopes, cathode ray tube displays, plasma displays, electrophosp1orescent and electro-flourescent displays. These viewing devices and text, photographs and pictures on paper, linen in books or on sheet materials are all to be classed as objects' for the purposes of this

description.

A device according to the invention may be used to produce distorted images for photographic or video reproduction or for entertainment or advertising purposes.

Software simulating the device according to the invention can be used in conjunction with a computer to produce contiguous magnification of image files for the same

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purposes as already listed, including particularly the production of maps containing areas of particular interest at a higher magnification than surrounding areas.

Software simulating the device according to the invention can be used in conjunction with a digital camera to produce contiguous magnification for the same purposes as already listed, including particularly the display of the centre of view at a higher zoom than that of the surrounding area.

A handle or handles can be formed by extending the outer parallel part of the lens.

Alternatively the lens could be held on its outside. Alternatively finger' holes could be formed in the lens material. A lens holder could be used to enable it to be stood at a fixed distance from printed work or for examination and. inspection of objects such as printed circuit boards.

An alternative design of lens could include the use of non-homogeneous materials, having a varying refractive index, higher in the centre - to give a greater magnification - and of value I at the edge - giving 0 magnification. Such a property could be derived by changes in chemical composition, or changes induced by temperature, electrical or magnetic means. The lens could be of a liquid material.

The lens could be of gas. The lens could be made of several parts, having different areas of curvature or different materials.

Claims

1. A lens made from refracting material including areas of differing magnification (curvature) which adjoin each other without producing any optical discontinuity.

2. A lens made from refracting material comprising a central nondistorting (spherical) area and an outer non-distorting area, the sections of the lens between the areas producing smooth transitions between the parts of the image without optical discontinuities.

(Application number GB 0510539.0)