GB2516099A

GB2516099A - Viewfinders

Info

Publication number: GB2516099A
Application number: GB1312482.1A
Authority: GB
Inventors: Richard Simpson; Craig Whitehill
Original assignee: EYEFINDER Ltd
Current assignee: EYEFINDER Ltd
Priority date: 2013-07-12
Filing date: 2013-07-12
Publication date: 2015-01-14
Also published as: GB201312482D0

Abstract

A viewfinder arrangement comprises a holder which is configured to be fitted to a smartphone comprising a camera. The viewfinder 10 comprises plural lenses 20, 22 in an afocal configuration. The holder and the viewfinder 10 define co-operating surface profiles whereby the viewfinder 10 is removably held by the holder when the holder is fitted to the smartphone.

Description

Title of Invention: Viewfinders

Field of the Invention

The present invention relates to a viewfinder arrangement for a smartphone comprising a camera and a smartphone arrangement comprising such a viewfinder arrangement.

Background Art

Smartphones often comprise a camera. The smartphone user typically composes a picture to be taken by way of a taking lens provided in the body of the smartphone by viewing the scene of interest on the main display of the smartphone.

The present inventors have recognised that the above described approach to picture composition has shortcomings for certain users. The present invention has been devised in the light of the inventors' appreciation of such shortcomings. It is therefore an object for the present invention to provide a viewfinder arrangement for a smartphone which comprises a camera. It is a further object for the present invention to provide a smartphone arrangement comprising a camera equipped smartphone and such a viewfinder arrangement.

Statement of Invention

According to a first aspect of the present invention there is provided a viewfinder arrangement comprising: a holder which is configured to be fitted to a smartphone which comprises a camera; and a viewfinder comprising plural lenses in a substantially afocal configuration, the holder and the viewfinder defining cooperating surface profiles whereby the viewfinder is removably held by the holder when the holder is fitted to the smartphone.

The viewfinder arrangement is brought into use by fitting the holder to a smartphone comprising a camera. The holder and the viewfinder define cooperating surface profiles. The viewfinder is then held by the holder by way of the cooperating surface profiles whereby the viewfinder is removably attached to the smartphone. The user of the srnartphone may compose a picture to be taken by the smartphone camera by way of the viewfinder. Such a viewfinder may provide for an improved user experience over the approach to composition by way of the main display of the smartphone. Such a viewfinder may also provide for improved optical performance compared with the main display of the smartphone. Many photographers consider composition by way of an optical viewfinder (OVF) to be superior to composition by way of electro-optical approaches on account of certain advantages, including the OVF providing "full resolution" (i.e. the resolution of the photographer's eye). The viewfinder of the present invention may be an optical viewfinder and thus may lack electro-optic components present in the like of electronic viewfinders (EVEs).

A physical path of an optical arrangement comprising the plural lenses may be substantially the same as a length of the optical path defined by the optical arrangement. An axis of the optical path defined by the optical arrangement may therefore be substantially straight. A viewfinder in which the physical path and the optical path are of substantially the same length may be more compact and less expensive than a viewfinder which employs folded optics. The configuration of a viewfinder in which the physical path and the optical path are of substantially the same length and which accommodates a relatively wide field of view is described below.

The holder may be configured and the surface profile may be disposed on the holder such that the viewfinder extends away from a side of the smartphone when the viewfinder is held by the holder and the holder is fitted to the smartphone. The holder may be configured thus such that the viewfinder extends away from one of a top side, bottom side or left or right side when the front face of the smartphone is viewed by a user in the proper orientation. The holder may be configured such that it extends along at least one side of the smartphone when the holder is fitted to the smartphone. More specifically the holder may be configured such that it extends around substantially all four sides of the smartphone. The holder may therefore have the form of a bumper case. The surface profile may be disposed on the holder such that the surface profile extends along at least one side of the smartphone when the holder is fitted to the smartphone. Where the holder is configured such that it extends around substantially all four sides of the smartphone, the surface profile may extend around most of the smartphone. There may be at least one break in the surface profile where the holder comprises at least one aperture to, for example, provide access to ports or to control buttons of the smartphone. The surface profile may be a recess. More specifically the surface profile may be a groove.

The viewfinder has a surface profile which cooperates with the surface profile of the holder whereby the viewfinder is removably held by the holder. The viewfinder may comprise a protrusion which comprises the surface profile. A distal portion of the protrusion may be shaped to be received in a recess defined by the holder. Where the holder defines a groove, the protrusion of the viewfinder may be received in one of plural locations in the groove whereby a location of the viewfinder in relation to the smartphone may be changed. The viewfinder and the holder may be configured such that the viewfinder is held relatively securely by the holder. Where one of the viewfinder and the holder defines a recess, a part defining the recess may be formed from a resilient material such as silicone rubber. A recess defining part which is formed of a resilient material may grip a protrusion received in the recess and thereby hold the viewfinder relatively securely. The holder may, for example, may be formed from silicone rubber and may define a groove which is operative to grip a protrusion which extends from the viewfinder.

The viewfinder may comprise an ocular lens and an objective lens. The viewfinder may comprise no lens further to the ocular and objective lenses. The viewfinder may thus comprise no more than two discrete lenses. The ocular and objective lenses may be coaxially disposed in relation to each other. The ocular lens may be a positive lens and the objective lens may be a negative lens. The viewfinder may therefore have a reverse Galilean configuration. At least one of the ocular and objective lenses may be aspheric. The positive ocular lens and the negative objective lens may substantially match each other. The objective lens may comprise a negative meniscus lens. The ocular lens may comprise a biconvex lens.

The viewfinder may be configured such that it defines an aspect ratio of one of 16:9, 4:3 and 3:2. Where the aspect ratio is 3:2, a width of the viewfinder may thus be 1.5 times a height of the viewfinder. More specifically the viewfinder may comprise a housing. The housing may have an aspect ratio of 3:2. An aperture of the viewfinder may have an aspect ratio of 3:2. A housing of the viewfinder may be configured to define an aperture having an aspect ratio of 3:2. For example the housing may extend from a periphery of the lenses towards an axis of the optical path of the lenses to define the aperture. The viewfinder may have a width between 15mm and 45 mm, between 20 mm and 40 mm or between 25 mm and 35mm.

More specifically the viewfinder may have a width of 30 mm. The viewfinder may have a height between 10mm and 40 mm, between 13 mm and 30 mm or between 15mm and 25 mm. More specifically the viewfinder may have a height of 20 mm.

The viewfinder may have a length (i.e. in a direction of the optical path) of less than 30mm, 25mm, 20mm, 18mm, 17mm, 16mm orlS mm. The length may be determined by the thickness of the plural lenses comprised in the viewfinder and by the separation of the plural lenses from each other.

The viewfinder may be configured to provide a field of view (FoV) of at least 30°, 35°, 40°, 45°, 50°, 55° or 60°. The viewfinder may be configured to provide a FoV which generally or perhaps even substantially matches the FoV of the camera of the smartphone with which the viewfinder is to be used. Smartphone cameras may have different FoVs. An FoV depends on the focal length of the camera and the width of the camera sensor.

The viewfinder may be configured to provide an eye-relief distance of more than 5 mm, 10mm, 15 mm, 20mm, 25mm, 30 mm, 35mm, 40 mm or 45 mm. Alternatively or in addition, the viewfinder may be configured to provide an eye-relief distance of less than 50 mm, 45 mm, 40 mm, 35 mm, 30 mm, 25 mm, 20 mm, 15 mm or 10 mm.

In a form of the viewfinder the eye-relief distance may be 25 mm. The viewfinder may be configured to substantially maintain focus of scenes seen through the viewfinder greater than 5 metres, 2 metres, 1 metre or 0.5 metres from the objective end of the viewfinder.

At least one lens comprised in the viewfinder may be formed from at least one of optical crown glass, high-index plastics material (thiourethanes) and optical plastics material, such as polycarbonate, PMMA or polystyrene. At least one face of at least one lens comprised in the viewfinder may comprise an anti-reflective coating, such as a coating comprising magnesium fluoride.

The viewfinder may comprise a housing. The housing may contain the plural lenses of the viewfinder. An interior surface of the housing may be configured to support and perhaps also to hold at least one lens. An exterior of the housing may define the surface profile that cooperates with the surface profile of the holder. More specifically the housing may define a protrusion. The protrusion may be elongate and may extend across a width of the housing, i.e. in a direction substantially perpendicular to the optical path. The protrusion may be integrally formed with the housing. The housing may be formed at least in part from an injection moulded thermoplastic material.

According to a second aspect of the present invention there is provided a smartphone arrangement comprising: a smartphone comprising a camera; and a viewfinder arrangement according to the first aspect of the present invention, the holder of the viewfinder arrangement being configured to be fitted to the smartphone.

Embodiments of the second aspect of the present invention may comprise one or more features of the first aspect of the present invention.

Brief Description of Drawings

Further features and advantages of the present invention will become apparent from the following specific description, which is given by way of example only and with reference to the accompanying drawings, in which: Figure 1A is a view from an ocular end of a viewfinder of an embodiment of the present invention; Figure 1 B is a view from an objective end of the viewfinder of Figure 1 A; Figure 1 C is a side view in cross-section of the viewfinder of Figures 1 A and 1B; Figure 1 D is a side view of a holder of an embodiment of the present invention; and Figure 2 is a representation of the optical components of the embodiment of the present invention.

Description of Embodiments

A view from an ocular end of a viewfinder 10 comprised in an embodiment of the invention is shown in Figure 1A and a view from an objective end of the viewfinder is shown in Figure lB. The viewfinder 10 comprises a housing 12 which encloses the lenses of the embodiment and which defines an integrally formed elongate protrusion 14 which extends across a width of the housing, i.e. in a direction substantially perpendicular to the optical path of the lenses. The lenses are described below with reference to Figures 1C and 2. The housing 12 is formed at least in part from an injection moulded thermoplastic material. As can be seen from Figures 1A and 1 B the housing is shaped such that it extends from a periphery of the lenses towards an axis of the optical path defined by the lenses on each of the ocular and objective sides of the lenses. The housing 12 extends in this fashion by a greater amount on the ocular side 16 than on the objective side 18 whereby the extent of the housing on the ocular side defines the greatest width and height of the optical path of the viewfinder so as to provide an aspect ratio of 3:2.

A side view in cross-section of the viewfinder 10 of Figures 1A and lB is shown in Figure 1C. As can be seen from Figure 1C, the housing 12 defines a space which holds an ocular lens 20 and an objective lens 22. The interior surface of the housing is shaped so as to hold the ocular and objective lenses 20, 22 in a proper relative disposition. The characteristics of the ocular and objective lenses 20, 22 are described below with reference to Figure 2. The length of the viewfinder 100.e.

along the optical path) is about 14 mm. The width of the viewfinder 10 is about 27 mm and the height of the viewfinder 10 is about 18 mm.

A side view of a holder 30 of an embodiment of the present invention is shown in Figure 1 D. The holder 30 is a bumper case of familiar form except as described below. The bumper case is shaped to fit securely around the four sides of a camera equipped smartphone and is configured so as not to obscure operative parts of the smartphone such as the main display, the taking lens of the camera, the input and output ports and the control buttons of the smartphone. The bumper case is formed of a resilient material such as silicone rubber. The bumper case of the present invention differs from familiar bumper cases in respect of the provision of a groove 32 which extends around the entire outer surface of the bumper case with the exception of locations where apertures are formed in the bumper case to provide access to the like of input and output ports.

A representation of the ocular and objective lenses 20, 22 of the embodiment of the present invention is provided in Figure 2. The ocular and objective lenses 20, 22 are aspheric with the ocular lens 20 being positive and the objective lens 22 being negative and having optical characteristics such that they are substantially matched.

The objective lens is a negative meniscus lens and the ocular lens is a biconvex lens. The ocular and objective lenses 20, 22 are formed from polycarbonate. The surfaces of the ocular and objective lenses 20, 22 have a magnesium fluoride comprising anti-reflective coating. The ocular and objective lenses 20, 22 are configured and relatively disposed so as to provide a field of view of 50° and an eye-relief distance of 25 mm. In addition the ocular and objective lenses 20, 22 are configured and relatively disposed so as to maintain focus of scenes seen through the viewfinder greater than 0.5 metres from the objective end of the viewfinder.

The embodiment of the present invention is brought into use by fitting the holder 30 to a camera equipped smartphone. The viewfinder 10 is then attached to the holder by inserting the protrusion 14 on the housing 12 of the viewfinder into a pad of the groove 32 defined around the exterior of the holder 30. The thickness of the protrusion 14 and the width of the groove 32 are such that the protrusion is a snug fit in the groove with the resilient nature of the material forming the walls of the groove being such as to grip the protrusion securely. The viewfinder 10 can be located at any position on a side of the smartphone with the exception of the four corners by inserting the protrusion 14 into the groove 32 at an appropriate location. The viewfinder can then be used to compose a picture to be taken by way of the camera comprised in the smartphone. After use the viewfinder is detached from the smartphone by gripping the viewfinder and smartphone and pulling the viewfinder and smartphone apart such that the protrusion 14 is withdrawn from the groove 32.

Claims

Claims 1. A viewfinder arrangement comprising: a holder which is configured to be fitted to a smartphone comprising a camera; and a viewfinder comprising plural lenses in a substantially afocal configuration, the holder and the viewfinder defining cooperating surface profiles whereby the viewfinder is removably held by the holder when the holder is fitted to the smartphone.
2. A viewfinder arrangement according to claim 1 in which the viewfinder is an optical viewfinder.
3. A viewfinder arrangement according to claim 1 or 2 in which a linear physical path of an optical arrangement comprising the plural lenses is substantially the same as a length of an optical path defined by the optical arrangement.
4. A viewfinder arrangement according to claim 3 in which a main axis of the o optical path defined by the optical arrangement is substantially straight.
5. A viewfinder arrangement according to any one of the preceding claims in which the holder is configured and the surface profile is defined by the holder such that the viewfinder extends away from a side of the smartphone when the viewfinder is held by the holder and the holder is fitted to the smartphone.
6. A viewfinder arrangement according to claim 5 in which the holder is configured such that, in use, the viewfinder extends away from one of a top side, bottom side, left side and right side of the smartphone when the front face of the smartphone is viewed by a user in the proper orientation.
7. A viewfinder arrangement according to any one of the preceding claims in which the holder is configured such that it extends along at least one side of the smartphone when the holder is fitted to the smartphone.
8. A viewfinder arrangement according to claim 7 in which the holder is configured such that it extends around substantially all four sides of the smartphone.
9. A viewfinder arrangement according to claim 7 or 8 in which the holder has the form of a bumper case.
10. A viewfinder arrangement according to any one of the preceding claims in which the surface profile is defined by the holder such that the surface profile extends along at least one side of the smartphone when the holder is fitted to the smartphone.
11. A viewfinder arrangement according to claim 10 and where the holder is configured such that it extends around substantially all four sides of the smartphone, in which the surface profile extends around substantially all four sides of the is smartphone.o
12. A viewfinder arrangement according to any one of the preceding claims in which the surface profile defined by one of the holder and the viewfinder is a groove and the surface profile defined by the other of the holder and the viewfinder is a protrusion.
13. A viewfinder arrangement according to claim 12 in which the surface profile defined by the holder is a groove and the surface profile defined by the viewfinder is a protrusion.
14. A viewfinder arrangement according to claim 12 or 13 where one of the viewfinder and the holder defines a groove, in which a part defining the groove is formed from a resilient material to thereby grip a protrusion defined by the other of the viewfinder and the holder.
15. A viewfinder arrangement according to any one of the preceding claims in which the viewfinder comprises an ocular lens and an objective lens.
16. A viewfinder arrangement according to claim 15 comprising no lens further to the ocular and objective lenses.
17. A viewfinder arrangement according to claim 15 or 16 in which the ocular and objective lenses are coaxially disposed in relation to each other.
18. A viewfinder arrangement according to any one of claims 15 to 17 in which the ocular lens is a positive lens and the objective lens is a negative lens whereby the viewfinder has a reverse Galilean configuration.
19. A viewfinder arrangement according to claim 18 in which the positive ocular lens and the negative objective lens substantially match each other.
20. A viewfinder arrangement according to any one of claims 15 to 19 in which is the objective lens comprises a negative meniscus lens and the ocular lens comprises a biconvex lens.
21. A viewfinder arrangement according to any one of the preceding claims in which the viewfinder is configured such that it defines an aspect ratio of one of 16:9, 4:3and3:2.
22. A viewfinder arrangement according to any one of the preceding claims in which the viewfinder comprises a housing, the housing extending from a periphery of the lenses towards an axis of the optical path of the lenses to define an aperture.
23. A viewfinder arrangement according to any one of the preceding claims configured to provide a field of view (F0V) of at least one of 30°, 35°, 40°, 45°, 50°, 55° and 60°.
24. A viewfinder arrangement according to any one of the preceding claims in which the viewfinder is configured to substantially maintain focus of scenes seen through the viewfinder greater than one of 5 metres, 2 metres, 1 metre and 0.5 metres from the objective end of the viewfinder.
25. A smartphone arrangement comprising: a smartphone comprising a camera; and a viewfinder arrangement according to any one of the preceding claims, the holder of the viewfinder arrangement being configured to be fitted to the smartphone. r