GB2284069A - Illuminated magnifying device with fresnel lens - Google Patents

Abstract

A magnifying device comprises a large Fresnel lens 101 in a frame 103. The frame 103 has means 109, 110 to keep the, frame at a suitable distance from the object 123 of study. Lighting means e.g. fluorescent lamps 111 which illuminates the object 123 are included in the frame 101. The means to keep the frame at a suitable distance may include devices 125 to keep books 123 and other uneven objects flat. The lens 101 may be protected by transparent sheets (119, 121, Fig.1). <IMAGE>

Description

ILLUMINATED LIGHTING DEVICE FIELD OF THE INVENTION This invention is related to a reading aid and in particular a lighted or illuminated magnifying device for persons of impaired vision.

BACKGROUND OF THE INVENTION Persons with impaired vision often have difficulties in reading text from books and newspapers. They are therefore often cut off from stimulating new information normally obtained from books and newspapers. In the case of elderly people, this make their days boring and cut them off from the current news in their society.

Conventional magnifying lenses based on conventional non-fresnel lenses do not solve this problem. A non-fresnel lens which is large enough to give a sufficiently large enlarged area is too heavy and expensive for most users. A "viewer for partially sighted persons" as disclosed in the patent application GB 1 220 802 has a large conventional lens. The problem of the weight of the large lens is in this case solved by mounting the lens over a baseboard using four adjustable distance studs. As the resulting device becomes heavy, the design incorporates a horizontally movable tray, on which the material to be read is placed in one position of the movable tray. The tray is then moved so that the material to be read is placed under the magnifying glass.

The design has several disadvantages. The distance from the magnifying lens to the material to be read will be different depending on the height of the book to be read, newspapers cannot easily be handled and the device is heavy, requires much space and it is difficult for elderly people to move such a device.

The US patent 4,120,564 discloses another design intended to handle the problem of heavy large conventional lenses.

In this design the large lens is mounted on an inclined stand for movement in two directions to permit the user to move the lens to a suitable position without having to use physical force to maintain the position of the heavy lens. The design has several disadvantages. The material to be read has to be placed behind the inclined lens, what is difficult for elderly people to perform, newspapers cannot easily be handled and the device is heavy, requires much space and it is difficult for elderly people to move the device.

Smaller magnifying lenses are often used. A medium sized conventional magnifying lens with a surrounding circular fluorescent lamp on a dual link, flexible arm is subsidized by the swedish state as an aid for visually handicapped persons. Small and medium sized lenses have a major disadvantage. The text which is to be read normally has line lengths which are longer than the area that can be read without moving the magnifying lens. The effort required to move the magnifying lens at least twice for each text line to be read is unacceptable for longer texts.

The problem caused by the weight of a large conventional lens can be solved by using fresnel lenses. The patents US 3,753,610 and US 4,457,585 discloses various mountings for fresnel lenses. None of these two designs solve two serious problems which are common when large fresnel lenses are used as a reading aid. Fresnel lenses of a sufficient size for the reading of a page in book obstruct the ambient light in two ways. Their optical effects will shade much of the light which would illuminate the object of interest if the lens was removed. Furthermore, they will act as fairly good spherical mirrors. The two fresnel mountings will therefore give unwanted and irritating images of light objects in a wide sector above the lens and these images will be added to the weak wanted image of the object of interest.The wanted image will be comparatively weak due to the reduced object illumination which is caused by the fresnel lens deflection of ambient light.

Available viewing aids for people with reduced sight is not good enough to permit them to read books and newspapers. Countries like Sweden supply handicapped people with handicap reducing equipment. The organisations concerned have not found any equipment on the market which fills the above requirement. As a very inferior substitute, a few new book titles are printed using large type (type height of approximatively 4 mm).

OBJECTS OF THE INVENTION It is a purpose of the invention to provide a magnifying lens device which permits the user to read at least half of one whole ordinary book page without having to move the magnifying device.

It is another purpose of the invention to provide a magnifying lens device which can easily be kept in a good reading position without requiring an active muscle effort of the user.

It is another purpose of the invention to provide a magnifying lens device which permits a clear view of the object to be read and a strong reduction of the interference caused by reflected images of irrelevant bright objects in the vicinity.

It is a further purpose of the invention to provide a magnifying lens which has a low mass so that it can be moved between different places also by elderly people.

It is another purpose of the invention to provide a magnifying lens device which does not occupy much space in the homes of the users.

SUMMARY OF THE INVENTION The purposes of the invention are achieved with a device, the features and characteristics of which are set out in the appended claims.

Thus the magnifying device has a large Fresnel lens disposes in a frame. The frame has means to keep the frame at a suitable distance from the object of study.

Lighting means which illuminates the object of study are included in the frame and are shielded not to issue light into the eyes of a user of the device. The means to keep the frame at a suitable distance are in some embodiments designed in a way suitable to keep books and other uneven objects of study flat.

BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of a magnifying device which are not intended to limit the invention will now be described with reference to the accompanying drawings in which - Fig. 1 shows a sectional side view of an embodiment of a magnifying device designed to be used with various object distance keeping means, - Fig. 2 shows a sectional side view of another embodiment of a magnifying device having integral object distance keeping means, and - Fig. 3 shows a top plan view of the magnifying device depicted in Fig. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS In Fig. 1 a magnifying device is shown in a sectional view as seen from the side. A Fresnel lens 101 being substantially flat and having a basically rectangular outline (compare Fig. 3) is inserted in an frame generally denoted 103 and made of an opaque or nontransparent material. The frame 103 comprises a top part 105 directly surrounding the Fresnel lens 101 and having its top surface located in parallel with and approximately in same plane as the top surface of the lens 101. At the inner edge of the top part 105 it is bent downwards and inwards to form a shelf 107 for supporting the marginal portion of the lens 101. The frame 103 also comprises a part 109 extending downwards from the outer edge of the top part 105 of the frame. The downwards protruding part 109 extends far beyond the bottom surface of the lens 101 and terminates in an inwardly, towards the centre of the Fresnel lens 101, bent foot portion 110 located in parallel with the top part 105 and the lens 101.

At the interior side of the downwards extending part 109, at the side facing the lens 101, along at least two opposite sides of the lens 101 elongated illuminating means are mounted, in the Figure illustrated as two fluorescent cylindrical lamps 111. Glow switches 113 are also mounted inside the frame 101. The lamps 103 thus have the conventional straight elongated tube shape and extend preferably along the long sides of the rectangular lens 101. Both the fluorescent tubes 111 and the glow switches 113 are located such as not to be visible from a point of vision above the Fresnel lens, where a user of the device will have his eyes when e.g. using the device for book or newspaper reading. They are thus mounted under the top frame part 103 thus being shielded thereby.

The fluorescent tubes 111 are so located and the top part 103 has such a width that the light therefrom will not be visible even from most other points above the Fresnel lens 101 except some points located very near the upper surface of the lens 101. The electrical wiring for distribution of electric power to the lamps 111 and the glow switches 113 is indicated at 115 and is attached to the inner side of the downwards extending frame part 109.

The fresnel lens 101 is comparatively large, preferably of a size which permits the simultaneous reading of at least half a common book page. Its area is therefore preferably at least 100 cm2, or preferably at least 200 cm2 or even 300 cm2, 400 cm2 or 500 cm2. It may thus be 26 x 20 cm which permits the reading of a page of approximatively 18 x 14 cm. Bushings 115 are located on the inwardly protruding lower part 110 of the frame 101 and permit, e.g. by virtue of an internal screwthread, the addition of various means to keep the device and thus the illuminated lens 101 at a suitable distance from the object to be viewed.

The intensive light permitted by the two fluorescent lamps 111 permits a high light intensity on the area to be observed. This intensive light will cause the eye pupil of a reader using the device to reduce in radius, thus increasing the depth of focus in the eye. In some cases the reduced pupil diameter also mask off distorting parts of the eye lens. Another wanted effect of the intensive light is that the unwanted reflected images from light objects above the fresnel lens, such as lamps in the room, will be less disturbing as their relative luminosity compared to the wanted image from the object under study will be reduced. Lamps close to the reading position can be switched off as the internal lamps of the reading device will be quite sufficient for the purpose of reading. This will further reduce the unwanted reflected images.

Also illustrated in the Figure is a transparent sheet cover 119 placed directly on top of the Fresnel lens 101.

The cover 119 can be cleaned and/or replaced when it is dirty and protects the fresnel lens 101, normally made of plastics, from wear. A similar protecting transparent sheet 121 may be placed directly at the bottom side of the lens 101.

Fig. 2 shows in a similar sectional view as Fig. 1 another embodiment of a magnifying device. In this embodiment the means to maintain a suitable distance from the fresnel lens 101 to the object under study is included in the frame 103. Thus the side frame part 109 extending downwards from the top frame part 105 is prolonged to give the desired distance. The lower inwards facing part 110 of the frame 101 is here intended to be placed directly on the newspaper, document etc which is to be studied. Especially useful in the case of a book as indicated at 123, means 125 will create a downkeeping force on the book, thus keeping the book reasonably flat.

The means 125 can be a glass or plastic plate as shown in Fig. 2 and they are attached to the foot portion 110, at the inner edge thereof which may have a suitable configuration for receiving the edge of a plate 125. In order to reduce the total weight of the magnifying device, the means 125 can instead be made from a few thin wires or bars, for example of stainless steel. This will obstruct the field of vision somewhat, but will eliminate the need of periodic cleaning of the surfaces of a plate 125.

By locating the bottom surface of the downkeeping means 125 somewhat higher than the level of the bottom part 110 of the frame 103, a newspaper to be read and placed underneath the downkeeping means 125 will have no contact with the surface of the means 125 or at least contact the surface thereof with small forces, thus reducing the rate with which newspaper printing ink will be deposited on the surface of the transparent means 125.

The glow switches 113 can be deleted if an electronic ballast is used. The electric wiring to the lamps 111 and the glow switches 113 is not drawn in Fig. 2 but it is to be retained in labyrinthic locking channels 127 in the side part 109.

A top view of the device of Fig. 2 is shown in Fig. 3 where the section line along which the view of Fig. 2 is seen is denoted II-II. At 129 a power cord is indicated supplying electric power to the illuminating means, which are well hidden by the top frame part 105.

Claims (9)

1. A magnifying apparatus comprising a Fresnel lens, at least one lamp for illuminating the object to be viewed and shielding means (sheltering device) arranged to prevent light from the at least one lamp from reaching the eyes of a user of the apparatus.

2. A magnifying apparatus as claimed in claim 1, wherein the sheltering device comprises a frame supporting the Fresnel lens.

3. A magnifying apparatus as claimed in claim 1, wherein the sheltering device comprises a frame made from a nontransparent material and including a top frame part directly surrounding and supporting the Fresnel lens and a side part extending downwards from the top part.

4. A magnifying apparatus as claimed in claim 3, wherein the at least one fluorescent lamp comprises fluorescent tubes located directly beneath the top frame part and extending along and in the vicinity of the side frame part.

5. A magnifying apparatus as claimed in claim 1, having a substantially transparent flat plane means located below and parallel to the Fresnel lens and also arranged to keep an object under study sufficiently flat and at a suitable distance from the Fresnel lens.

6. A magnifying apparatus as claimed in claim 5, wherein the plane means below the Fresnel lens comprises a transparent sheet of glass or plastics, in particular acrylic glass.

7. A magnifying apparatus as claimed in claim 5, wherein the plane means below the Fresnel lens comprises thin wires, bars or a net.

8. A magnifying apparatus as claimed in one of claims 5 7, wherein the sheltering device comprises a frame made from a nontransparent material and including a top frame part directly surrounding and supporting the Fresnel lens and a side part extending downwards from the top part, the plane means being attached to the bottom part of the side frame part.

9. A magnifying apparatus substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawings.