GB2242539A

GB2242539A - Collapsible viewing devices

Info

Publication number: GB2242539A
Application number: GB9006104A
Authority: GB
Inventors: James Brian Sharp
Original assignee: SCHAFLINE Ltd
Current assignee: SCHAFLINE Ltd
Priority date: 1990-03-17
Filing date: 1990-03-17
Publication date: 1991-10-02
Also published as: GB9006104D0

Abstract

A viewing device which enables a person to look in a downwards direction whilst viewing a scene straight ahead of the viewing device comprises four rectangular planar sections 1,3,5,7 which are hinged together at 11,13,15,17, to form a collapsed flattened configuration or an expanded cuboid configuration determined by folding connection members 19 which interconnect two adjacent sections 1,7. A lens 9 is provided in one section 1 and an adjacent section 3 is semi-transparent. A mirror 33 hinged at 35 to a section 7 is at 45 DEG to the lens 9 and the semi-transparent section 3 and is at the focus of the lens 9. Thus the device can be expanded for use and collapsed for storage. <IMAGE>

Description

DESCRIPTION "IMPROVEMENTS RELATING TO VIEWING DEVICES" The present invention relates to a viewing device.

More particularly the present invention relates to a viewing device for use in viewing selected scenes, such viewing devices being commonly used by artists and photographers so that the artist or photographer can continue to look in a downwards direction whilst viewing a scene or selected part thereof, straight ahead of the viewing device.

Viewing devices of this type are commonly termed 'camera obscurers' and they generally comprise a lense which is located so as to focus an image on a mirror which is arranged at 450 angle to the optical axis of the lens, a semi-transparent planar sheet being located at 900 to the lens so as to enable the image received by the mirror, to be viewed through said sheet. As will be appreciated such camera obscurers are relatively bulky and awkward items especially when being transported or stored.

The aim of the present invention is to provide a viewing device which provides the required optical performance but which may be collapsed quite simply for transport and/or storage.

According to the present invention there is provided a viewing device comprising a first rectangular planar section incorporating a lens such that the optical axis of the lens extends normally to the first rectangular planar section, one edge region of said first rectangular planar section being hinged to an edge region of a second rectangular section which is semi-transparent, the edge of said second section which extends parallel to the hinge between the first and second sections, being hinged to a third rectangular section, and the edge region of said third section, which extends parallel to the aforementioned hinges, being itself hinged to a fourth rectangular planar section, the remaining edge regions of said first and fourth sections, which are parallel to the aforementioned hinges, being hinged together, a mirror being hinged to the surface of said fourth section so as to lie substantially flat over part of the third and fourth sect ions when said sections are hinged to a substantially flat position, and to slide over the third section as the sections are hinged from the substantially flat position towards a ready for use position determined by a connection member which extends between two adjacent sections to limit their movement apart, the mirror being inclined at 450 to said fourth section at the focus of said lens, when in the ready for use position.

In a preferred embodiment of the present invention the said sections are of identical dimensions and two connection members are provided, each connection member being in the form of a rectangular planar section of like dimensions to said first to fourth sections, with a fold line diagonally thereacross, two adjacent edge regions of each connection member being hinged to edge regions of the first and fourth sections. Thus, in the substantially flat folded position, the connection members fold so that the fold line moves away from said sections, and in the ready for use position the connection members complete a cuboid form for the viewing device.

Various dimensions and shapes are of course possible for the said sect ions and connection members the prime criterion being that the mirror can obtain a 45 to the optical axis of the lens at the focus of the lens, with the semi-transparent section i.e. said second section, being at 900 to the plane of the lens.

Preferably said first section and the connecting members of the preferred embodiment are each extended to provide an integral screen in the ready for use position, around- three sides of the semi-transparent second section to improve viewing of an image. This integral screen has suitable fold lines so that it will allow the device to collapse as before, for transport and/or storage.

Preferably the device of the present invention is constructed from a single blank of material which is suitably shaped with appropriate fold lines, with the semi-transparent second section and the mirror hingedly attached at appropriate positions.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a preferred embodiment of the present invention; Fig. 2 is a perspective view of the arrangement of the operational components of the preferred embodiment; Fig. 3 is a perspective view of the embodiment of Figs. 1 and 2 when partially collapsed; Fig. 4 is a perspective view of the embodiment of Figs. 1 and 2 when fully collapsed.

Fig. 5 is a plan view of a blank with associated parts attached, for use in constructing the preferred embodiment of Figs. 1 and 2; and Fig. 6 is a cross-sectional view of the blank of Fig. 5, taken along line A-A.

The preferred embodiment of the present invention illustrated in the accompanying drawings is a generally cuboid form of camera obscurer. As best seen from Fig. 3, the cuboid form is basically formed by four planar square sections, 1, 3, 5 and 7 of like dimensions. First section 1 incorporates an optical lens 9 and is hinged at 11 to an edge of second section 3. Second section 3 is a semi-transparent screen and this second section is hinged at 13, parallel to hinge 11, to an edge of third section 5, the opposite parallel edge of the third section 5 being hinged at 15 parallel to the aforementioned hinges, to an edge of the fourth section 7. The edges of the first and fourth sections which are parallel to the hinges 11 and 15 respectively, are hinged together at 17.This construction can thus be folded to a collapsed state or expanded to a cuboid form, the cuboid form being dictated by connection members 19 which are hingedly secured to adjacent side edges 21 and 23 of the first and fourth sections 1, 7 respectively, these connection members 19 incorporating a fold line 25 which allows the cuboid form to be folded substantially flat. The connection members 19 and said first section 1, also have extended regions 27 and 29 respectively, which are hinged together at 31 and which form a screen around the semi-transparent section 3 to facilitate viewing.

This is best seen in Fig. 1 of the accompanying drawings.

To complete the obscurer a rectangular planar mirror 33 is hinged along one edge 35 to the surface of said fourth section 7, within the cuboid form, said one edge 35 being parallel to all of the hinges 11, 13,-15 and 17. The edge 37 of the mirror 33, which is parallel to edge 35, merely rests against said third section 5 and slides thereover as the cuboid form is collapsed or expanded. The dimensions of the mirror 33 and the position of the hinge 35 are selected so that the mirror is at an angle of 45 to the surfaces of the third and fourth sections 5, 7 when the obscurer is in the expanded cuboid form, with optical axis of the lens 9 engaging the reflecting surface of the mirror at the focus of the lens 9. In this way a focussed image can be viewed through the semi-transparent second section 3. For storage or transport the obscurer is merely collapsed substantially flat.

To construct the preferred embodiment of the present invention as described hereabove, a blank as shown in Fig. 5 can be cut from a suitable material with hinges 15, 17 and 21 being formed as fold lines.

The remaining hinges can be formed by any suitable connection means.

Whilst the above described preferred embodiment of the present invention incorporate square planar sections 1, 3, 5 and 7, any alternative rectangular shapes can of course be selected and different sections can have different rectangular shapes. The prime criterian is that the mirror in the expanded form'of the obscurer is at 450 to the optical axis of the lens and the semi-transparent viewing section, and at the focus of the lens.

The present invention thus provides a simple camera obscurer which can be easily collapsed for storage and transport, and readily expanded when required for use.

Claims

1. A viewing device comprising a first rectangular planar section incorporating a lens such that the optical axis of the lens extends normally to the first rectangular planar section, one edge region of said first rectangular planar section being hinged to an edge region of a second rectangular section which is semi-transparent, the edge of said second section which extends parallel to the hinge between the first and second sections, being hinged to a third rectangular section, and the edge region of said third section, which extends parallel to the aforementioned hinges, being itself hinged to a fourth rectangular planar section, the remaining edge regions of said first and fourth sections, which are parallel to the aforementioned hinges, being hinged together, a mirror being hinged to the surface of said fourth section so as to lie substantially flat over part of the third and fourth sections when said sections are hinged to a substantially flat position, and to slide over the third section as the sections are hinged from the substantially flat position towards a ready-for-use position determined by a connection member which extends between two adjacent sections to limit their movement apart, the mirror being inclined at 45 to said fourth section at the focus of said lens, when in the ready for use position.

2. A viewing device as claimed in claim 1, in which two connection members are provided, each connection member being in the form of a rectangular planar section, two adjacent edge regions of each connection member being hinged to the edge regions of two adjacent sections, with a fold line extending diagonally across each connection member from the hinge between said two adjacent sections.

3. A viewing device as claimed in claim 2, in which the said sections are of identical dimensions and the connection members are of like dimensions to said sections.

4. A viewing device as claimed in claim 2 or 3, in which the connecting members are connected between the said first and fourth sections and are each extended, together with said first section, to provide an integral screen in the expanded ready-for-use position, around three sides of the semi-transparent second section.

5. A viewing device as claimed in any one of the preceding claims, in which the device is constructed from a single blank of material with the semitransparent second section and said mirror hingedly attached at the appropriate positions.

6. A viewing device constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.