GB2279156A

GB2279156A - Stereo viewer

Info

Publication number: GB2279156A
Application number: GB9411838A
Authority: GB
Inventors: Anthony Tak Sau Lo
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-18
Filing date: 1994-06-13
Publication date: 1994-12-21
Also published as: DE9409549U1; CN2197681Y; GB9312644D0; JPH0713104A; GB9411838D0

Abstract

A folding stereo viewer comprises support means 46, 48 for holding a print 56 in an upright position for viewing. The body 55 of the viewer comprises a pair of folding body members (3, Fig. 3) 4. A lens support member 2 is provided which is foldable into a body member (3, Fig. 3). The lens support member 2 may move through an angle greater than 90 DEG to reach the unfolded condition, and adjustment of the angle is possible to suit the vision of different people. An end wall 45 of a body member 4 is adapted for positioning the viewer for direct viewing of a print mounted on the page of a photograph album. Edge support means 46, (47, Fig. 6), 48 is also provided on a stereo viewer for holding a margin extending along a single edge of a print 56 for mounting on the viewer. <IMAGE>

Description

STEREO VIEWER This invention relates to a stereo viewer and particularly, but not exclusively, to a folding stereo viewer for stereo viewing photographic prints comprising two printed images positioned adjacent to each other.

According to a first aspect of the present invention a folding stereo viewer comprises a respective lens for viewing each image of a pair of printed images to be viewed, and a body providing support for the lenses and having locating means for the printed images, the body extending in use in the space between the locating means and a plane intersecting the optical centres of the lenses and which is substantially parallel to the printed images, a portion of the body intermediate the locating means and the plane being pivotable to enable the body to fold on itself to achieve a folded condition of the viewer.

Desirably the pivotable portion is located substantially half way along the length of the body so that the body can assume substantially half its normal length in the folded condition.

In a preferred embodiment, the body is disposed diagonally in use with respect to the optical axes of the lenses and the surface of the printed images.

Preferably the main wall of the body is curved for increased strength.

To avoid the need for the user's eyes to diverge when viewing images separated by more than the distance between the eyes (something most people find uncomfortable and difficult to achieve), each said lens is preferably a single element configured to act also as an optical wedge.

Preferably the viewer comprises a lens support means for supporting the lenses on the body which is pivotable with respect to the body.

Desirably the extent of pivotable movement of the lens support means with respect to the body can be selected to provide focus adjustment for different users, and preferably provides at least substantially a half-diopter of focus adjustment. Conveniently the selection is made by use of alternative detent means provided on the viewer.

A second aspect of the invention concerns location of a pivotable connection of a lens support means facilitating a shorter body length.

According to a second aspect of the present invention a folding stereo viewer comprises lens support means for holding a respective lens for viewing each image of a pair of printed images to be viewed, and a body provided with locating means for positioning the printed images, the body extending in use between the locating means and the lens support means, and the lens support means having a pivotable connection with the body so as to fold with respect to the body to achieve a folded condition of the viewer, the pivotable connection being disposed in use of the viewer nearer to the printed images than the lenses.

Desirably the lens support means folds into the body in the folded condition of the viewer. Typically the geometry of a viewer in accordance with the second aspect of the invention involves the lens support means folding through an angle greater than 900 to reach the folded condition, the angle most desirably being substantially in the range 110 to 140". In a preferred embodiment, the angle though which the lens support means folds is substantially 125".

According to a third aspect of the invention, instead of having a back plate on which the printed images are supported in a stereo viewer (which need not be a folding stereo viewer), locating means for the printed images comprises edge support means adapted to support a print or prints bearing the images at least substantially, the edge support means holding a marginal portion of the print or prints extending along a single edge thereof.

The edge support means preferably comprises a recess and a cooperating projection directed into the recess, a print being located with respect to the viewer by insertion of part of said marginal portion of the print into the recess so as to be interposed between the wall of the recess and the projection. Preferably the insertion requires slight bending of a flat print. In the bent condition the print may then act as a spring, resiliently pressing against the projection and against the wall of the recess and thereby generating enough friction to hold itself securely in place.

Preferably the edge support means also comprises additional slots for receiving other parts of said marginal portion in order to assist in supporting the print, to provide reaction forces to limit the extent of bending of the print, and to provide increased frictional engagement.

By being held in a slightly bent condition, the print is also assisted in remaining upright instead of bending over under its own weight.

Such locating means avoids the need for metal springs which are expensive, or plastic springs which tend to fatigue and take set positions easily.

In addition the locating means preferably comprises an end surface of the body which may be disposed substantially perpendicular to the focal axes of the lenses, and which may be placed on a page of a photograph album to align the viewer for directly viewing prints mounted on the page. Preferably the surface defines an edge for aligning with an edge of a print to be viewed in order to assist in positioning the viewer relative to the print.

By way of example only embodiments of a stereo viewer in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagram in perspective of a stereo camera and a prior art stereo print viewer, Figure 2 is a diagram in perspective of a stereo viewer showing the lenses misaligned with the printed images being viewed, Figure 3 is an isometric view showing an assembly for a folding stereo viewer, Figure 4 is a side view showing a typical prior art stereo viewer, and underneath the folding stereo viewer of Figure 3, Figure 5 is a further side view of the folding stereo viewer of Figure 3, shown in full line, superimposed over a side view of the typical prior art stereo viewer of Figure 4, which is shown to the same scale in chain line, Figure 6 is a partial plan view showing mounting of a print in a further embodiment of a stereo viewer, and Figure 7 is a perspective view showing mounting of a print in the viewer of Figure 6.

With reference to Figure 1, a typical stereo camera 20 has two lens systems 21 22 for producing respective photographic images 23, 24 of a subject 25. The developed photographic print or prints containing images 23 and 24 can be transferred to a stereo print viewer 30 for viewing simultaneously with a pair of lenses 32, 33. Each lens is positioned for viewing through by one of the user's eyes, 18, 19.

Since the lens systems 21, 22 of the camera are separated so as to give slightly different images of the subject 25 in a similar way to the images created by a person's eyes, the lenses in the stereo print viewer can be arranged to recreate a pair of coinciding virtual images 25' of the printed images 23 and 24 which have the appearance of a single stereo image. That is to say the subject 25 appears to be recreated in three dimensions.

Since Sir C Wheatstone invented stereo photography, many variations have been created for the design of a stereo print viewer. However, the typical features are those shown for the stereo print viewer 30 of Figure 1. This has a back plate 31 on which the print or prints are held for viewing, and a body 34 to maintain the correct relationship between the prints and the lenses 32, 33.

Some known stereo viewers are better than others however because they are easier and more comfortable to look through.

The better viewers present a pair of well aligned virtual images at a point of coincidence typically in the region of 1 to 5 metres in front of the observer. To achieve this the body 34 must be very rigid as a slight misalignment, indicated at 35 in Figure 2, between the horizontal line 36 joining the optical centre of lenses 32, 33 and the horizontal line 37 joining the centres of the two images 23, 24 will result in image displacement which is detectable by the users brain. A small displacement will cause eye strain and headache as the eyes try to compensate for the error, whilst a big displacement-will make it impossible for the user to fuse the two images into a single stereo image.

The Loreo Stereo Camera, which is the subject of UK patent specification GB 2185823, can produce stereo prints using standard prints and standard processing, and has thus created an increased need for a good, low cost compact viewer to enable the camera owners to share the joys of stereo photography by sending stereo prints to friends accompanied by a high quality, cheap and compact stereo viewer.

The folding stereo viewer common to Figures 3, 4 and 5 was created as a response to this need, and achieves pocket size (20mm x lOOmm x 80mm) whilst keeping all the-benefits of a good stereo viewer. It also has the advantage that stereo prints filed in a photo album can be viewed.

With reference to Figure 3, the lenses 1 of the viewer are configured to act also as optical wedges, to avoid the need for the user's eyes to diverge in viewing images on a print which are more widely spaced than the eyes. Thus, each lens is a plano-convex lens but with the centre of curvature of the convex face offset horizontally from that axis which extends through the centre of the planar face and normal thereto.

In manufacture the lenses are press-fitted into a lens support means in the form of moulded plastics lens support member 2, which has a pair of apertures 5 for viewing through the lenses. Instead of a press-fit attachment of the lenses to the lens support member 2, the lenses may be attached by adhesive or cement. Each of the two lower, outer corners of the lens support member 2 is provided with a boss 6 having a central socket 7 therein. A first moulded plastics body member 3 is provided with respective inwardly directed spigots 8 which snap fit on assembly into the sockets on the lens support member 2 to form a pivotable connection 50 therewith (see Figures 4 and 5). A respective flange 9 is provided above each spigot 8, at least an upper portion 9a of the inwardly directed edge of each flange 9 being of pointed form.

First body member 3 has a strengthening rib 11, a pair of side walls 12 and a bottom panel 13 which together define a recess 14.

By virtue of the pivotable connection of the lens support member 2 and the first body member 3 the lens support member 2 can fold into the recess 14 in the folded condition of the viewer. On unfolding the lens support member 2 from the recess 14, further movement will be resisted when the upper portion 10 of each flange 8 encounters the first detent of a pair of detents 15 disposed above each socket 7 of the lens support member 2. In this condition the lenses may be in an appropriate position for viewing. However, if focal adjustment is required, pulling on the lens support member 2 with increased force will be sufficient to cause flange portions 9a to ride over the first detent of each pair 15 to come to rest between the detents in a second position of the lens support member 2.

If still more adjustment is required the lens support member can be pulled further to bring flange portions 9a past the second detent of each pair of detents 15, where further movement in the same direction is prevented by abutment of the flanges 9 with end stops 10 on the lens support member 2.

Cut-outs 16 formed in body member 3 set back the connection of bottom panel 14 from the end portion 12a of each side wall 12 bearing spigots 8 and flanges 9. This arrangement enables the end portions 12a to flex, so facilitating both the snap-fitting of the spigots 8 into the sockets 7 in the lens support member, and movement of flange portions 9a past each of the detents 15. Detents 15 correspond in pointed form to the pointed form of flange portions 9a which further facilitates such movement.

Opposite end portions 12b of side walls 12, which bear outwardly directed sockets 17, protrude beyond bottom panel 13 and strengthening rib 11, and are thus enabled to flex inwardly to a degree.

On assembly of the viewer, the end portions 126 are inserted into slots 50 in the second moulded plastics body member 4, the slots being formed between the curved main wall 41 and opposite side walls 42. End portions 42a of the side walls 42 each bear a respective inwardly directed spigot 43. By virtue of the adjacent slots 40, the end portions 42a of the side walls 42 are able to flex outwardly.

As the end portions 12b are inserted into the slots 40, the flexibility of the end .portions 12b and 42a enables spigots 43 to enter the sockets 17 so as to form a pivotable connection therebetween (see Figures 3 and 4).

Once lens support member 2 has been folded into the recess 14 in first body member 3, pivotable connection 51 enables both lens support member 2 and body member 3 to be folded into a recess 44 defined within main wall 41, side walls 42 and an end wall 45 of body member 4, so achieving the fully folded condition of the viewer.

Just before the first body member 3 and lens support member 2 reach the fully folded condition within recess 44 of body member 4, restraining means (not shown) is encountered giving a resistive force which must be overcome to reach the fully folded condition.

Similarly, the restraining means provides a resistive force to unfolding, and thus helps to prevent the viewer unfolding inadvertently.

Preferably the restraining means comprise a rib on each end portion 12b of the first body member, and each rib must be made to override a similar rib on the corresponding end portions 42a of body member 4 to reach the folded condition, and on unfolding. The resistive force provided by the restraining means corresponds to the force required to make the ribs override.

Main wall 41 of body member 4 is curved for increased strength.

Reference 60 in Figures 4 and 5 denotes the viewer in the assembled, fully unfolded condition. By way of comparison the Loreo stereo viewer of the prior art is also shown at 70, the lens to print distance being the same for this, and any like parts being denoted with like reference numerals.

In the drawings it is apparent that the lens support member 2 in the inventive viewer 60 is shaped to orient the lenses 1 relative to the pivotal connection 50, such that in use the pivotable connection 50 is significantly closer to the print 56 than the lenses 1, whereas the lenses 1 and pivotable connection 50 are at the same distance.

The advantage of this is that the body 55 in the inventive viewer 60 is shorter than the body 55 in the prior art viewer 70 even in the unfolded condition. This further reduces the small size already achieved in the folded condition by body members 3 and 4 folding along the axis of pivotable connection 51.

Another effect of the design of the lens support member 2 in reducing the body length is that it must be folded through more than the 90" required by the prior art device to reach the folded condition against the body 55, although in the inventive viewer this angle is increased still further to substantially 125 by the body 55 being disposed along a diagonal in use with respect to the print 56 and the focal axes 59 of the lenses. The body is designed to be disposed diagonally in this manner since it has been realised that this can reduce the amount of material required to make the viewer in comparison with utilising an orthogonal arrangement such as that of the prior art device 70.

In the prior art device the back plate 31 is also pivotable through 90 , about a pivotable connection 57, in order to attain the folded condition. However, in the inventive viewer edge support means is provided on the body member 4 for holding the print 56, instead of a back plate.

This enables the body member 4 to be provided with an edge 58 which can be placed against the edge of a print to align the viewer relative to the print for viewing when the print is mounted in a photograph album. The planar portion 59 of the outer surface of end wall 45 is oriented such that, when placed flat against a page of the photograph album, the lenses 1 will be correctly positioned for viewing the print.

Referring now to the embodiment of a stereo viewer shown in Figures 6 and 7, the edge support means comprises a projection 46 in the form of a fin which protrudes -from the main wall 41 beyond the plane defined by the inner surface 49 of end wall 45 and into a recess 47 in end wall 45. The edge support means also comprises a slot 48 formed between each side wall 42 and the end wall 45.

For the edge of a print 56 to be engaged by the edge support means, the print must be bent slightly to pass a margin thereof behind the projection 46 in order to enter the recess 47. The margin is also inserted into slots 48, limiting the extent to which the print 56 bends as shown in Figures 6 and 7. Resilience of the print in tending to straighten causes it to press against slots 48, recess 47 and projection 46 and so generate enough frictional engagement to hold the print securely in place even if the viewer is accidentally turned upside down as it is passed from person to person as a favourite print is being shared.

The embodiment having body member 4, as shown in Figure 3, has identical edge support means.

Claims

1. A folding stereo viewer comprising a respective lens for viewing each image of a pair of printed images to be viewed, and a body providing support for the lenses and having locating means for the printed images, the body extending in use in the space between the locating means and a plane intersecting the optical centres of the lenses and which is substantially parallel to the printed images, a portion of the body intermediate the locating means and the plane being pivotable to enable the body to fold on itself to achieve a folded condition of the viewer.

2. A viewer as claimed in claim 1 in which said pivotable portion is located substantially half way along the length of the body so that the body can assume substantially half its normal length in the folded condition.

3. A viewer as claimed in claim 1 or claim 2 comprising a lens support means for supporting the lenses on the body which is pivotable with respect to the body.

4. A folding stereo viewer comprising lens support means for holding a respective lens for viewing each image of a pair of printed images to be viewed, and a body provided with locating means for positioning the printed images, the body extending in use between the locating means and the lens support means, and the lens support means having a pivotable connection with the body so as to fold with respect to the body to achieve a folded condition of the viewer, the pivotable connection being disposed in use of the viewer nearer to the printed images than the lenses.

5. A viewer as claimed in claim 4 in which the lens support means folds through an angle greater than 90" to reach the folded condition.

6. A viewer as claimed in claim 5 in which the angle is substantially in the range 110 to 140".

7. A viewer as claimed in claim 5 or claim 6 in which the angle is substantially 125".

8. A viewer as claimed in any one of claims 3 to 7 in which the extent of pivotable movement of the lens support means with respect to the body can be selected to provide focus adjustment for different users.

9. A viewer as claimed in claim 8 in which the selection is made by use of alternative detent means.

10. A viewer as claimed in any one of claims 3 to 9 in which the lens support means folds into the body in the folded condition of the viewer.

11. A stereo viewer comprising a respective lens for viewing each image of a pair of printed images to be viewed, and a body provided with locating means for positioning the printed images, the locating means comprising edge support means adapted to support a print or prints bearing the printed images at least substantially, the edge support means holding the print or prints by a marginal portion of the print or prints extending along a single edge thereof.

12. A viewer as claimed in claim 11 in which the edge support means comprises a recess and a cooperating projection directed into the recess, a print being located with respect to the viewer by insertion of part of said marginal portion of the print into the recess so as to be interposed between the wall of the recess and the projection.

13. A viewer as claimed in claim 12 in which the edge support means also comprises additional slots for receiving other parts of said marginal portion in order to assist in supporting the print.

14. A viewer as claimed in any one of claims 11 to 13 in which the print is held in a slightly bent condition.

15. A viewer as claimed in any one of the preceding claims in which the body is disposed diagonally in use with respect to the optical axes of the lenses and the surface of the printed images.

16. A viewer as claimed in any one of the preceding claims in which a main wall of the body is curved for increased strength.

17. A viewer as claimed in any one of the preceding claims in which the locating means also comprises an end surface of the body which may be disposed substantially perpendicular to the focal axes of the lenses, and which may be placed on a page of a photograph album to align the viewer for directly viewing prints mounted on the page.

18. A viewer as claimed in claim 17 in which an edge of said end surface is provided for aligning with an edge of a print to be viewed in order to assist in positioning the viewer relative to the print.

19. A viewer as claimed in any one of the preceding claims in which each said lens is a single element configured to act also as an optical wedge.

20. A folding stereo viewer substantially as described herein with reference to Figures 3, 4 and 5.

21. A stereo viewer having edge support means substantially as described herein with reference to Figures 6 and 7.