GB2426813A

GB2426813A - A method and apparatus for testing the focus, alignment and field of view angle of a lens of a camera

Info

Publication number: GB2426813A
Application number: GB0603198A
Authority: GB
Inventors: Padraic Anthony Moran; Joseph Gerard Mannion; David John Fadden
Original assignee: Hi Key Ltd
Current assignee: Hi Key Ltd
Priority date: 2005-06-02
Filing date: 2006-02-16
Publication date: 2006-12-06
Also published as: GB0603198D0

Abstract

Apparatus 1 for testing the focus, alignment and field of view angle of a lens (2, Fig. 1) of a CMOS camera 3 comprises an object card 21 mounted on a support frame 20 for testing and setting the focus of the camera 3. First and second carrier members 85,86 carrying first, second, third and fourth alignment bands (89,90,91,92, Fig. 7) are located in a housing 25 for testing the alignment and field of view angle of the camera 3. A camera carrier 42 pivotally mounted on a saddle 45 carries the camera 3 under test. The saddle 45 is slideable on a guide track 46 between a first position (Fig. 3) with the camera 3 under test aligned with the object card 21 for setting the focus of the camera 3, and a second position (Fig. 4) with the camera 3 aligned with the first and second carrier members 85,86 for testing the alignment and field of view angle of the lens (2, Fig. 1) of the camera 3. The camera carrier 42 is pivotal on the saddle 45 from a first orientation (Fig. 3) with the camera 3 under test aligned with the object card 21, and a second orientation (Fig. 4) with the camera 3 under test aligned with the first and second carrier members 85,86.

Description

"A method and apparatus for testing the focus, alignment

and field of view angle of a lens of a camera"

The present invention relates to a method and apparatus for testing the focus, alignment and field of view angle of a lens of a camera, and the invention also relates to a camera having been tested using the apparatus according to the invention, and also using the method according to the invention.

In the manufacture of cameras, and in particular, digital cameras, for example, CMOS digital cameras, it is important that the focus of the lens should be accurate, and the lens should be accurately aligned with a light sensitive CMOS chip in the camera. Additionally, it is important that the field of view angle of the lens relative to the light sensitive CMOS chip in the camera should also be accurate. Itis particularly important that in fixed focus cameras the lens should be accurately focused relative to the light sensitive CMOS chip.

Various test apparatus are provided for carrying out tests for testing the focus of a lens of a camera, other test apparatus are provided for facilitating testing the alignment of the lens in a camera, and test apparatus is also known for carrying out tests for testing the field of view angle of a lens of a camera. However, in general, it is necessary to obtain specific pieces of test apparatus for testing each of the properties of the focus, alignment and field of view angle of the lens of a camera.

This, in turn, requires transferring of the camera from one test apparatus to the next in order to carry out the necessary tests for testing the focus, alignment and field of view angle of the lens. The transfer of a camera to be tested from one test apparatus to another in general requires manual transferring of the camera from one apparatus to the next, which is time consuming, and can also lead to damage of the camera, since the more handling to which a camera is subjected, the greater is the danger of damage occurring to the camera. While it is possible to provide automatic conveying systems between such test apparatus, conveying systems tend to be relatively cumbersome, and are also relatively expensive. Additionally, even with the provision of conveying systems between test apparatus, transferring of a camera from one test apparatus onto the conveying system and then from the conveying system onto another test apparatus, and so on is still not eliminated. There is therefore a need for apparatus for testing the focus, alignment and field of view angle of a lens of a camera which overcomes these problems of known test apparatus.

The present invention is directed towards providing a method and apparatus for testing the focus, the alignment and the field of view angle of a lens of a camera, and the invention is also directed towards providing a camera tested by the apparatus and by the method.

According to the invention there is provided apparatus for testing the focus, alignment and field of view angle of a lens of a camera, the apparatus comprising: a first support means for supporting an object card having a focus test is pattern thereon located to be focused on by a camera under test for testing the focus of the lens thereof, a second support means supporting an alignment test means, the alignment test means being provided for testing the alignment and field of view angle of a lens of a camera under test, and being located to be focused on by the camera, a camera support means for receiving and supporting a camera under test, the camera support means being selectively moveable between a first position co- operating with the first support means for facilitating focusing a camera under test on the object card for testing the focus of the lens of the camera, and a second position co-operating with the second support means for facilitating focusing a camera under test on the alignment test means for testing the alignment of the lens relative to the camera and the field of view angle of the lens, and a guide means for guiding the camera support means between the first and the second positions.

In one embodiment of the invention the camera support means comprises a saddle engageable with the guide means and moveable between the first and the second positions, and a camera carrier for releasably receiving and supporting a camera under test, the camera carrier being mounted on the saddle.

Preferably, the camera carrier is pivotally mounted on the saddle, and is pivotal between a first orientation co-operating with the first support means when the saddle is in the first position for facilitating focusing a camera under test on the object card, and a second orientation cooperating with the second support means when the saddle is in the second position for facilitating focusing a camera under test on the alignment test means.

Advantageously, an operating means is provided for pivoting the camera carrier from the first orientation to the second orientation as the saddle is being urged from the first to the second position.

In one embodiment of the invention the operating means for pivoting the camera carrier between the first and second orientations comprises a cam follower co- operable with a cam, one of the cam and cam follower being located on the camera carrier, and the other being rigidly coupled to the guide means. Preferably, the cam follower is located on the camera carrier. Advantageously, the cam defines an elongated camming surface extending parallel to the guide means and being shaped for co-operating with the cam follower for pivoting the camera carrier between the first and the second orientations.

In one embodiment of the invention the cam defines a first elongated camming surface segment extending parallel to the guide means for retaining the camera carrier in the first orientation, and a second camming surface segment stepped from the first camming surface segment and extending parallel to the guide means for retaining the camera carrier in the second orientation, and an intermediate camming surface segment extending between and joining the respective first and second camming surface segments and extending at an angle less than 900 relative to the respective first and second camming surface segments Preferably, the intermediate camming surface segment extends relative to the first and second camming surface segments at an angle of approximately 45 .

In one embodiment of the invention the camera carrier is pivotal through an angle of approximately 900 between the first and second orientations.

In another embodiment of the invention the first support means supports the object card above the camera support means for viewing along a substantially vertically extending axis, and the operating means locates the camera carrier in the first orientation with the central axis of the lens of a camera under test extending substantially vertically and perpendicularly to the object card when the saddle is in the first position.

In a further embodiment of the invention the second support means supports the alignment test means for viewing along a substantially horizontal axis, and the operating means locates the camera carrier in the second orientation with the central axis of the lens of a camera under test extending substantially horizontally and perpendicularly to the alignment test means when the saddle is in the second position.

Preferably, a releasable securing means is provided for releasably securing a camera under test in the camera carrier.

Advantageously, a first retaining means is provided for retaining the camera support means in the first position, and a second retaining means is provided for retaining the camera support means in the second position.

In one embodiment of the invention the camera support means is slideable on the guide means between the first and the second positions. Preferably, the guide means comprises an elongated guide track for guiding the camera support means between the first and the second positions.

In one embodiment of the invention the alignment test means comprises a pair of spaced apart first alignment elements, and a pair of spaced apart second alignment elements, the respective first and second alignment elements being provided on the second support means, the first alignment elements being located eq ui-spaced apart from and on opposite sides of a central focus point on the second support means along a first axis, and the second alignment elements being located equi-spaced apart from and on opposite sides of the central focus point along a second axis, the second axis extending substantially perpendicularly to the first axis, so that when the camera support means is in the second position with a camera under test of ideal field of view angle and alignment aligned with the central focus point, the respective first and second alignment elements should appear at the edge of an image thereof formed by the lens on a photosensitive medium in the camera under test.

In another embodiment of the invention the spacing of the second alignment elements from the central focus point is substantially similar to the spacing of the first alignment elements from the central focus point.

In a further embodiment of the invention the alignment test means further comprises a pair of spaced apart third alignment elements, and a pair of spaced apart fourth alignment elements, the third alignment elements being provided on the first support means equi-spaced apart from and on opposite sides of the central focus point along the first axis, and the fourth alignment elements being provided on the second support means equi- spaced apart from and on opposite sides of the central focus point along the second axis, so that when the camera support means is in the second position with a camera under test of ideal field of view angle and alignment aligned with the central focus point, the respective third and fourth alignment elements should appear at the edge of an image thereof formed by the lens on the photosensitive medium of the camera under test.

In one embodiment of the invention the spacing of the third alignment elements from the central focus point is greater than the spacing of the first alignment elements from the central focus point.

In one embodiment of the invention the spacing of the fourth alignment elements from the central focus point is greater than the spacing of the third alignment elements from the central focus point.

In one embodiment of the invention the alignment test means comprises a first elongated carrier member and a second elongated carrier member, the first and second carrier members being arranged in cruciform formation, the third alignment elements being carried on the first carrier member and the fourth alignment elements being carried on the second carrier member. Preferably, the respective first and second carrier members are of arcuate shape in respective directions extending along the corresponding ones of the first and second axes, and advantageously, the radius of curvature of the first carrier member is slightly greater than the radius of curvature of the second carrier member.

In one embodiment of the invention each third and fourth alignment element is provided by a corresponding third and fourth alignment band extending transversely of the corresponding first and second axes. Preferably, the third and fourth alignment bands are of substantially similar width. Advantageously, the third and fourth alignment bands are of width in the range of 5mm to 15mm. Ideally, the third and fourth alignment bands are of width approximately 10mm.

In one embodiment of the invention the first alignment elements are carried on the first carrier member, and the second alignment elements are carried on the second carrier member.

In another embodiment of the invention each first and second alignment element is provided by a corresponding first and second alignment band extending transversely of the corresponding first and second axes. Preferably, the first and second alignment bands are of substantially similar width. Advantageously, the first and second alignment bands are of width in the range of 5mm to 15mm. Ideally, the first and second alignment bands are of width approximately 10mm.

Advantageously, a plurality of spaced apart intermediate alignment elements are provided on the second support means located between and spaced apart from each first alignment element and the corresponding adjacent third alignment element along the first axis, and between and spaced apart from each second alignment element and the corresponding adjacent fourth alignment element along the second axis. Preferably, each intermediate element is provided by an intermediate band extending transversely of the corresponding one of the first and second axes.

Advantageously, the width of each intermediate band lies in the range of 5mm to 15mm. Preferably, the width of each intermediate band is approximately 10mm.

In one embodiment of the invention the second support means comprises a housing defining a hollow interior region, and the alignment test means is located in the hollow interior region, a communicating opening being provided through the housing to the hollow interior region for providing visual access to the alignment test means by a camera under test when the camera support means is in the second position co-operating with the housing for focusing the camera under test on the alignment test means.

In another embodiment of the invention a first light source is located in the hollow interior region of the housing for testing the ability of a camera under test to adjust to changes in light intensity.

In one embodiment of the invention the object card is provided mounted on the first support means, and the object card comprises a plurality of locations, the locations carrying respective patterns for testing corresponding respective functions of the focusing of a camera under test. Preferably, one of the locations on the object card is provided with a plurality of parallel first focus bands extending in a first direction, another one of the locations on the object card is provided with a plurality of parallel second focus bands extending substantially transversely relative to the direction of the first focus band. Advantageously, another one of the locations of the object card comprises a plurality of parallel third focus bands extending at an angle relative to the first focus bands and the second focus bands. Ideally, the third focus bands extend at an angle of approximately 45 to the first and second focus bands.

In another embodiment of the invention another one of the locations comprises a grid pattern formed by fourth and fifth focus bands, the fifth focus bands extending substantially perpendicularly to the fourth focus band. Preferably, another one of the S locations on the object card comprises a plurality of colour focus bands of respective different colours. Advantageously, the respective colour focus bands are of different widths.

In one embodiment of the invention a glare guard is provided for reflecting light from a camera under test when the camera support means is located in the first position.

In another embodiment of the invention the apparatus is adapted for testing the focus, alignment and field of view angle of a lens of a digital camera under test.

Preferably, a control circuit is provided for monitoring electronic signals outputted by a digital camera under test in response to the digital camera being sequentially aligned with the object card, the alignment test means and the first light source.

Advantageously, the control circuit monitors electronic signals outputted by a digital camera under test which are indicative of images formed by the lens thereof.

In one embodiment of the invention the apparatus is adapted for testing a CMOS camera.

Additionally, the invention provides a method for testing the focus, alignment and field of view angle of a lens of a camera in test apparatus, the method comprising the steps of supporting an object card having a focus test pattern thereon on a first support means of the test apparatus so that a camera under test can be focused on the object card for testing the focus thereof, supporting an alignment test means for testing the alignment of the lens of a camera under test and the field of view angle of the lens thereof on a second support means of the test apparatus, supporting a camera under test on a camera support means of the test apparatus, and selectively and alternately locating the camera support means in a first position co-operating with the first support means for facilitating focusing a camera under test on the object card for testing the focus of the lens of the camera under test, and a second position cooperating with the second support means for facilitating focusing a camera under test on the alignment test means for testing the alignment of the lens of the camera under test and the field of view angle of the lens of the camera under test.

The invention also provides a method for testing the focus, alignment and field of view angle of a lens of a camera using the apparatus according to the invention, the method comprising the steps of supporting an object card on the first support means, placing the camera under test on the camera support means of the apparatus and selectively and alternately locating the camera support means in a first position co- operating with the first support means for facilitating focusing the camera under test on the object card for testing the focus of the lens of the camera under test, and a is second position co-operating with the second support means for facilitating focusing the camera under test on the alignment test means for testing the alignment of the lens of the camera under test and the field of view angle of the lens of the camera under test.

Further the invention provides a camera tested on the apparatus according to the invention, and preferably, using the method according to the invention.

In one embodiment of the invention the focus of the camera is tested.

In another embodiment of the invention the alignment of the lens in the camera is tested, and in a further embodiment of the invention the field of view angle of the lens of the camera is tested.

In one embodiment of the invention the camera is a fixed focus camera, and typically, the camera is a digital camera.

The advantages of the invention are many. A particularly important advantage of the invention is that it provides a single apparatus which permits the focus, the alignment and the field of view angle of a lens of a camera to be tested. Since all three properties of a camera can be tested on the one apparatus, there is no need to provide transfer apparatus for transferring the camera to be tested from one piece of test apparatus to another. This, thus, considerably improves the efficiency of testing the focus, the alignment and the field of view angle of a lens of a camera, and also minimises any danger of damage to the camera during the test procedure.

A further advantage of the invention is achieved when as well as providing first and second alignment elements for testing the alignment and field of view angle of the lens of a camera, the apparatus is also provided with third and fourth alignment elements for testing the alignment and field of view angle of the lens of a camera, since the apparatus according to the invention can be used for testing two different types of cameras with lenses of respective different fields of view angles, the first and second alignment elements being used for testing the alignment and field of view angle of the lens of one type of camera, and the third and fourth alignment elements being used for testing the alignment and field of view angle of another type of camera.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a transverse cross-sectional side elevational view of a camera to be tested on apparatus according to the invention, Fig. 2 is an end elevational view of apparatus according to the invention for testing the focus, the alignment and the field of view angle of a lens of the camera of Fig. 1, Fig. 3 is a side elevational view of a portion of the apparatus of Fig 2, Fig. 4 is a partly cross-sectional side elevational view of the portion of Fig. 3 of the apparatus of Fig. 2, illustrating part of the apparatus of Fig. 2 in a different position, Fig. 5 is a cross-sectional end elevational view of a detail of the apparatus of Fig. 2, Fig. 6 is a partly cross-sectional side elevational view of the portion of Fig. 5 of the apparatus of Fig. 2, Fig. 7 is an end elevational view of another portion of the apparatus of Fig. 2, Fig. 8 is an underneath plan view of another portion of the apparatus of Fig. 2, and Fig. 9 is a block representation of electronic circuitry of the apparatus of Fig. 2.

Referring to the drawings, there is illustrated apparatus according to the invention, indicated generally by the reference numeral 1, for testing the focus, the alignment and the field of view angle of a lens 2 of a camera 3. In this embodiment of the invention the apparatus 1 is particularly suitable for testing the focus, the alignment and the field of view angle of a lens 2 of a CMOS camera 3, which is illustrated in Fig. 1, and which comprises a light sensitive CMOS chip 4 with which the lens 2 is to be accurately aligned and focused. Indeed, the apparatus 1 is suitable for testing the focus, the alignment and the field of view angle of the lens 2 of a CMOS camera 3 in which the camera is a fixed focus camera, and the apparatus 1 is suitable for testing the focus, the alignment and the field of view angle of two types of fixed focus CMOS cameras 3 in which the respective CMOS cameras 3 have different field of view angles.

Referring initially to Fig. 1, each CMOS camera 3 to be tested by the apparatus 1 comprises a camera housing 5 within which the light sensitive CMOS chip 4 is located. A lens housing 6 of circular transverse crosssection carries the lens 2, and the lens housing 6 is provided with an external screw thread 7 for engaging a corresponding threaded bore 9 in the camera housing 5, so that as the lens housing 6 is rotated in the threaded bore 9, the spacing of the lens 2 from the CMOS chip 4 is varied for adjusting the focus of the lens 2 of the camera 3 during testing of the camera 3 in the apparatus 1. Once the lens 2 has been correctly focused with the CMOS chip 4, the position of the tens housing 6 in the camera housing 5 is fixed, thereby preventing further adjustment of the spacing of the lens 2 from the CMOS chip 4. Electronic circuitry 10 illustrated in block representation in Fig. 1 reads signals from the CMOS chip 4 for forming and storing an electronic image of an object on which the camera 3 is focused. The lens 2 defines a central axis 11 which should be accurately aligned with the CMOS chip 4. Such CMOS cameras will be well known to those skilled in the art, and it is not intended to describe the CMOS camera in further detail.

Referring now to Figs. 2 to 9, the apparatus 1 for testing the focus, the alignment and the field of view angle of the lens 2 of the camera 3 comprises a bench 15 comprising a bench top plate 16 supported on four ground engaging legs 17 extending downwardly from the bench top plate 16. A pair of upstanding support members 19 extend upwardly from the bench top plate 16 for supporting a first support means, namely, a support frame 20 for supporting an object card 21 having a test pattern 23 printed thereon for facilitating testing and setting the focus of the camera 3 under test, see Fig. 8. Mounting brackets 24 extend downwardly from the support frame 20 for carrying the object card 21 in a substantially horizontal plane.

A housing 25 secured to the bench 15 at one end thereof comprises a base 27, a front panel 28, a rear panel 29, both of which extend upwardly from the base 27, and are joined by a pair of spaced apart side panels 30 and a top panel 31. The base 27, front, rear, side and top panels 28, 29, 30 and 31 together define a hollow interior region 32, within which is located a second support means, namely, a support upright 34 which extends upwardly from the base 27. An alignment test means comprising an alignment test element 35 is secured to the support upright 34 by a mounting member 36 for facilitating testing the alignment and the field of view angle of the lens 2 of the camera 3 under test as will be described below. A communicating opening 38 in the front panel 28 of the housing 25 accommodates the lens housing 6 of the camera 3 under test for facilitating focusing the camera 3 on the alignment test element 35. A first light source 39 is carried on a carrier bracket 40 extending from the mounting member 36, and is located within the hollow interior region 32 of the housing 25 but close to the communicating opening 38 for testing the ability of the cameras 3 under test to adjust to changes in light intensity, as will be described below. The alignment test element 35 and the first light source 39 are centrally located relative to and aligned with the communicating opening 38.

A second light source 41 mounted in the hollow interior 32 of the housing 25 illuminates the hollow interior region 32, and in turn the alignment test element 35 for facilitating viewing thereof by the cameras 3 under test.

A camera support means for supporting the camera 3 under test comprises a camera carrier 42, having a camera locating recess 43 for releasably receiving and locating the camera 3 under test, and a saddle 45 which pivotally carries the camera carrier 42. The saddle 45 is slideably engageable with a guide means, namely, a guide track 46 mounted on the bench top plate 16, and is slideable between a first position, illustrated in Figs. 2 and 3, with the camera carrier 42 co-operating with the support frame 20 and the object card 21 for testing the focus of the lens 2 of the cameras 3, and a second position, illustrated in Fig. 4, with the camera carrier 42 co- operating with the housing 25 and the alignment test element 35 for testing the alignment and the field of view angle of the cameras 3. The guide track 46 is of dovetail cross-section and is secured to the bench top plate 16 by screws (not shown). The saddle 45 comprises a sliding block 47 having a guide groove 48 of dovetail cross-section, corresponding to the dovetail cross-section of the guide track 46, formed therein for slideably engaging the guide track 46. A mounting member 49 extends upwardly from the sliding block 47 and carries a pivot pin 50 which defines a pivot axis 51 extending transversely of the guide track 46, about which the camera carrier 42 is pivotal. A longitudinally extending groove 52 extends through the camera carrier 42 for accommodating the mounting member 49, and a bore 54 extending into the camera carrier 42 pivotally engages the pivot pin 50. The camera carrier 42 is pivotal on the pivot pin 50 through an angle of 900 between a first orientation illustrated in Figs. 2 and 3 so that when the saddle 45 is in the first position, the camera 3 under test is focused on the object card 21 with the central axis 11 of the lens 2 of the camera 3 extending substantially vertically, and a second orientation illustrated in Fig. 4, so that when the saddle 45 is in the second position, the camera 3 under test is focused on the alignment test element 35 in the housing for testing the alignment and the field of view angle of the camera 3 with the central axis of the lens 2 of the camera 3 extending substantially horizontally.

A releasable securing means comprising toggle clamps (not shown) are mounted on the camera carrier 42 adjacent the camera locating recess 43 for securing the camera 3 under test in the camera locating recess 43, so that when the camera carrier 42 is in the second position and in the second orientation, as illustrated in Fig. 4, a camera under test locatedin the camera locating recess 43 with an ideal lens alignment and an ideal field of view angle would be in perfect alignment with the alignment test element 35 in the housing 25.

A first retaining means comprising a first ball catch 55 located in the guide track 46 co-operates with a corresponding recess 56 in the saddle 45 located within the guide groove 48 for locating and retaining the saddle 45, and in turn, the camera carrier 42 in the first position illustrated in Figs. 2 and 3, see Fig. 3. A second retaining means comprising a second ball catch 57 located in the guide track 46 co- operates with the recess 56 in the saddle 45 for locating and retaining the saddle 45, and in turn, the camera carrier 42 in the second position illustrated in Fig. 4. Each of the first and second ball catches 55 and 57 comprises a ball 58 located in a corresponding cavity 59 formed in the guide track 46 and the bench top plate 16. A compression spring of each ball catch 55 and 57 urges the corresponding ball into engagement with the recess 56 in the saddle 45, when the saddle 45 is in the corresponding one of first and second positions.

An operating means for pivoting the camera carrier 42 from the first orientation to the second orientation as the saddle 45 is being urged from the first position to the second position comprises a cam/cam follower mechanism 61. The cam/cam follower mechanism 61 comprises an elongated cam recess 62 which defines respective opposite camming surfaces 63 and 64 formed in a camming plate 65, which extends upwardly from and is secured to the bench top plate 16. A cam follower 67 which is rotatably carried on a shaft 68 extending from the camera carrier 42 is engageable in the cam recess 62 and co-operable therewith for pivoting the camera carrier 42 about the pivot axis 51 between the first orientation and the second orientation. The cam recess 62 comprises a first elongated camming segment 69 and a second elongated camming segment 70 stepped from the first camming segment 69, both of which extend longitudinally and parallel to the guide track 46. An intermediate segment 71 extends between the first segment 69 and the second segment 70 at approximately 45 and joins the first and second camming segments 69 and 70 together. Accordingly, as the saddle 45 is moved in the direction of the arrow A from the first position to the second position on the cam follower 67 engaging the intermediate camming segment 71, further movement of the saddle 45 in the direction of the arrow A towards the second position pivots the camera carrier 42 from the first orientation to the second orientation, and vice versa, when the saddle 45 is being urged in the reverse direction, namely, in the direction of the arrow B from the second position to the first position. Additionally, the first camming segment 69 of the cam recess 62 retains the camera carrier 42 in the first orientation, and the second camming segment 70 of the cam recess 62 maintains the camera carrier 42 in the second orientation.

An anti-glare shield 72 is carried on a carrier bracket 73, which is slideably mounted on one of the support members 19 for protecting the camera 3 under test from glare from the surrounding overhead lighting during testing of the focus of the camera 3 when the camera carrier 42 is in the first position and in the first orientation. A central opening (not shown) through the anti-glare shield 72 provides visual access for the camera 3 under test to the object card 21. l6

Returning now to the object card 21, the object card 21 is carried on the support frame 20 at a distance of approximately 1,500mm from the camera carrier 42, and when the saddle 45 is in the first position and the camera carrier 42 is in the first orientation, the camera 3 under test located in the camera locating recess 43 of the camera carrier 42 is aligned with the object card 21, with the central axis 11 of the lens 2 extending in a generally vertical direction towards the object card 21 and perpendicular thereto. The test pattern 23 on the object card 21 is provided with a plurality of locations 75 which carry different patterns for testing and setting the focus of the camera 3 under test. Locations 75a and 75b carry printed words, namely, the word "rearview", which is printed in reverse in location 75a, and the words "camera board", which are printed in reverse in the location 75b. Longitudinally extending bars 76 are printed in location 75c, while transversely extending bars 77 and 78 are printed in locations 75d and 75e, respectively. The transverse bars 77 and 78 extend perpendicularly to the longitudinally extending bars 76. The longitudinally extending bars 76 and the transversely extending bars 78 are of substantially similar width, while the transversely extending bars 77 are of narrower width than the transversely extending bars 78. Diagonally extending bars 79 are printed in location 75f and extend at an angle of approximately 45 relative to the longitudinal bars 76 and the transverse bars 77 and 78. The diagonally extending bars 79 are of substantially similar width to the longitudinal bars 76. A grid pattern 80 of longitudinally and transversely extending bars 81 is printed in location 75g, and colour bands 82 are printed in locations 75h and 75i, respectively. The bars and colour bands printed in the respective locations 75c to 75i and the letters printed in the locations 75a and 75b are provided for facilitating testing and setting the focus of the lens 2 relative to the CMOS chip 4 of the camera 3 under test.

Referring now to Figs. 4 and 7, the alignment test element 35 comprises first and second carrier members 85 and 86, respectively, arranged at right angles to each other in cruciform formation. The first and second carrier members 85 and 86 are secured on the support upright 34 by the mounting member 36 with the first carrier member 85 extending substantially vertically and defining a vertically extending first axis 87, and the second carrier member 86 extending substantially horizontally and defining a horizontally extending second axis 88. The first and second carrier members 85 and 86 are of arcuate shape as will be described below.

Referring in particular to Fig. 7, the first carrier member 85 carries a pair of first alignment elements provided by a pair of first alignment bands 89, and the second carrier member 86 carries a pair of second alignment elements, namely, a pair of second alignment bands 90, which in combination are provided for testing the alignment and the field of view angle of the lens 2 of one of the types of camera 3.

The first carrier member 85 carries a pair of third alignment elements provided by a pair of third alignment bands 91, and the second carrier member 86 carries a pair of fourth alignment elements, namely, a pair of fourth alignment bands 92, which in combination are provided for testing the alignment and the field of view angle of the lens 2 of the other type of camera 3, which has a wider field of view angle than the camera 3 for which the first and second alignment bands 89 and 90 are provided.

Intermediate alignment elements provided by intermediate alignment bands 93 are located on the first and second carrier members 85 and 86 intermediate the corresponding first and third alignment bands 89 and 91, respectively, and intermediate the second and fourth alignment bands 90 and 92, respectively, for determining the amount by which the alignment and the field of view angle of the lens 2 is offset from the ideal for both of the types of camera 3 to be tested.

The first and second alignment bands 89 and 90 are of similar widths, in this case 10mm wide, and are provided on the first and second carrier members 85 and 86, respectively, equi-spaced from a central focus point 94 defined by the point of intersection of the first and second axes 87 and 88. The distance of the first and second alignment bands 89 and 90 from the central focus point 94 is such that for each camera 3 under test of the narrower field of view angle, if the lens 2 is accurately aligned with the CMOS chip 4, and the field of view angle of the lens is correct, an image of the first and second carrier members 85 and 86 should be formed by the camera 3 which would show the first and second alignment bands 89 and 90 adjacent the periphery of the image. If the first and second alignment bands 89 and 90 do not appear in the image adjacent the periphery thereof, either the lens 2 of the camera 3 under test is not accurately aligned with the CMOS chip 4 or the field of view angle of the lens 2 is incorrect. If the image comprises all the first and second alignment bands 89 and 90, but the alignment bands are not adjacent the periphery of the image, the field of view angle of the lens 2 of the camera 3 under test is incorrect. Similarly, if none of the first and second alignment bands 89 and 90 appear in the image, the field of view angle of the lens 2 of the camera 3 under test is also incorrect. If only one of the first alignment bands 89 and only one of the second alignment bands 90 appear in the image, then the lens 2 of the camera 3 under test is not accurately aligned with the CMOS chip 4. Since in this embodiment of the invention the distance of the first and second alignment bands 89 and 90 from the central focus point 94 is similar, this arrangement of first and second alignment bands 89 and 90 is suitable for testing the alignment of the lens and field of view angle of the lens 2 of a camera 3 under test where the field of view angles of the lens are similar in the first and second axes directions, in other words, in the X- and Y-axis directions.

The third and fourth alignment bands 91 and 92 are of similar widths, in this case 10mm, however, in this case, while the third alignment bands 91 are equi- spaced from the central focus point 94, and the fourth alignment bands 92 are equi-spaced from the central focus point 94, the fourth alignment bands 92 are spaced from the central focus point 94 a greater distance than the third alignment bands 91 are spaced from the central focus point 94. Additionally, the distances of the third and fourth alignment bands 91 and 92 from the central focus point 94 is greater than the distance of the first and second alignment bands 89 and 90 from the central focus point 94. Thus, the third and fourth alignment bands 91 and 92 are suitable for testing the alignment and field of view angle of the lens 2 of a camera 3 under test of a wider field of view angle than can be tested with the first and second alignment bands 89 and 90, and also with a wider field of view angle in a direction along the second axis 88, in other words, in the X-axis direction, namely, the horizontal direction, than in a direction along the first axis 87, in other words, in the Yaxis direction, namely, the vertical direction.

Testing of the alignment and field of view angle of the lens 2 of the camera 3 under test with the third and fourth alignment bands 91 and 92 is similar to that described with reference to the first and second alignment bands 89 and 90 in that for a correctly aligned lens 2 of the correct field of view angles, the third and fourth alignment bands 91 and 92 should appear at the periphery of an image of the first and second carrier members 85 and 86 formed by the camera 3.

The intermediate alignment bands 93 are provided on the first and second carrier members 85 and 86, respectively, for indicating by how much the alignment and the field of view angle of the lens 2 of the camera 3 under test are off.

Additionally, the first and second carrier members 85 and 86 are of arcuate shape, and are radiused so that the images of the first and second carrier members 85 and 86 formed by the cameras 3 under test of the wider viewing angle appear flat. The radius of curvature of the first carrier member 85 is slightly greater than the radius of curvature of the second carrier member 86, in order to compensate for the greater distance which the fourth alignment bands 92 are spaced from the central focus point 94 to that which the third alignment bands 91 are spaced from the central focus point 94. By providing the first and second carrier members 85 and 86 of such arcuate shape, the distance by which the first and second carrier members 85 and 86 should be mounted from the camera 3 under test is significantly reduced, particularly in the case of the cameras 3 of the wider field of view angles.

A control circuit 95 is provided in the apparatus 1 for reading signals from the camera 3 under test, which are indicative of the images formed by the camera 3 under test, see Fig. 9. Cables 96, which terminate in the camera locating recess 43 of the camera carrier 42, and which are coupled to the camera 3 under test when the camera 3 under test is secured in the camera locating recess 43, deliver signals from the camera 3 under test to the control circuit 95. The control circuit 95 relays the signals from the camera 3 under test to a computer 97. The computer 97 under the control of suitable software reads the signals from the camera 3 under test and displays the images formed by the camera 3 under test on a visual display screen 98. An operator on viewing the images of the pattern 23 of the object card 21 displayed on the visual display screen 98 can adjust the spacing of the lens 2 from the CMOS chip 4 for setting the focus of the camera 3 under test. By inspecting the image displayed on the visual display screen 98 of the carrier members 85 and 86, an operator can determine whether the lens 2 of the camera 3 under test is accurately aligned with the CMOS chip 4 of the camera 3 and also if the field of view angle of the lens is correct.

In use, a camera 3 to be tested is secured in the camera locating recess 43 of the camera carrier 42, and the saddle 45 is urged into the first position and retained therein by the first retaining ball catch 55. The camera carrier 42 is retained in the first orientation by the cooperating action of the cam follower 67 with the camming surfaces 63 and 64 of the first camming segment 69 of the cam recess 62. At this stage the camera 3 under test in the camera carrier 42 is accurately aligned with the object card 21. The camera 3 under test is powered up and an image of the test pattern 23 of the object card 21 formed by the camera 3 under test is displayed on the visual display screen 98. An operator adjusts the lens housing 6 of the camera 3 until the test pattern 23 of the object card 21 is in focus. At this stage the lens housing 6 is permanently secured in position in the camera housing 5, thereby setting the focus of the camera 3 under test.

The saddle 45 is then urged from the first position to the second position in the direction of the arrow A, and as the saddle 45 is travelling from the first position to the second position, the co- operating action of the cam follower 67 with the camming surfaces 63 and 64 of the intermediate segment 71 of the cam recess 62 pivots the camera carrier 42 from the first orientation into the second orientation. The saddle is urged in the direction of the arrow A until the second retaining ball catch 57 engages the recess 56 in the saddle 45, thereby locating and retaining the saddle 45 in the second position with the camera carrier 42 in the second orientation and retained therein by the co-operating action of the cam follower 67 with the camming surfaces 63 and 64 of the second camming segment 7 of the cam recess 62. In this position, the lens housing 6 of the camera 3 under test projects into the communicating opening 38 In the housing 25, and the central axis 11 of the lens 2 of a camera under test in which the lens 2 is accurately aligned would coincide with the central focus point 94 of the alignment test element 35. With the camera 3 under test still powered up, the first light source 39 is powered by an electrical pulse to provide a high intensity flash of light for testing the ability of the camera 3 under test to adjust to changes in light intensity. The image of the alignment test element 35 provided on the visual display screen 98 by the camera 3 under test is inspected during and after the camera 3 under test is subjected to the high intensity flash of light to visually check its ability to adjust to the change in the light intensity.

As the camera 3 is recovering from the high intensity flash of light, the alignment and field of view angle of the lens 2 is tested by inspecting the image formed on the visual display screen 98 of the first and second carrier members 85 and 86 of the alignment test element 35 as already described. On completion of the alignment and field of view angle test on the camera 3 under test, the saddle 45 is urged in the direction of the arrow B back to the first position, and as the saddle 45 is travelling in the direction of the arrow B to the first position, the co-operating action of the cam follower 67 with the intermediate segment 72 the cam recess 62 urges the camera carrier 42 from the second orientation to the first orientation. On being returned to the first position, the first retaining ball catch 55 engages the recess 56 in the saddle 45, thus locating and retaining the saddle 45 in the first position. The camera 3 under test is then removed from the camera carrier 42, and the next camera 3 to be tested is engaged and secured in the camera locating recess 45 of the camera carrier 42.

While the apparatus according to the invention has been described as comprising a specific type of alignment test element, it will be readily appreciated that other suitable alignment test elements may be used. It is also envisaged that other suitable test patterns on the object card may be provided besides the test pattern which has been described. Additionally, while the apparatus has been described as being suitable for testing focus, alignment and field of view angle of a lens of a camera of two types of camera, it will be readily apparent to those skilled in the art that the apparatus may be provided for testing the focus, alignment and field of view angle of a lens of any number of cameras, and it will be readily apparent to those skilled in the art that by merely adapting the alignment test element to suit one or more different types of camera, the apparatus may be adapted for testing cameras of any field of view angle and similarly, by altering the spacing between the camera and the object card, cameras of different focal lengths can be accommodated While the apparatus has been described in particular for testing the focus, the alignment and the field of view angle of digital cameras, it will be readily apparent to those skilled in the art that the apparatus may be used for testing the focus, alignment and field of view angle of any type of camera, digital, analogue or otherwise.

Claims

Claims 1. Apparatus for testing the focus, alignment and field of view

angle of a lens of a camera, the apparatus comprising: a first support means for supporting an object card having a focus test pattern thereon located to be focused on by a camera under test for testing the focus of the lens thereof, a second support means supporting an alignment test means, the alignment test means being provided for testing the alignment and field of view angle of a lens of a camera under test, and being located to be focused on by the camera, a camera support means for receiving and supporting a camera under test, the camera support means being selectively moveable between a first position co- operating with the first support means for facilitating focusing a camera under test on the object card for testing the focus of the lens of the camera, and a second position co-operating with the second support means for facilitating focusing a camera under test on the alignment test means for testing the alignment of the lens relative to the camera and the field of view angle of the lens, and a guide means for guiding the camera support means between the first and the second positions.
2. Apparatus as claimed in Claim 1 in which the camera support means comprises a saddle engageable with the guide means and moveable between the first and the second positions, and a camera carrier for reteasably receiving and supporting a camera under test, the camera carrier being mounted on the saddle.
3. Apparatus as claimed in Claim 2 in which the camera carrier is pivotally mounted on the saddle, and is pivotal between a first orientation co-operating with the first support means when the saddle is in the first position for facilitating focusing a camera under test on the object card, and a second orientation co-operating with the second support means when the saddle is in the second position for facilitating focusing a camera under test on the alignment test means.
4. Apparatus as claimed in Claim 3 in which an operating means is provided for pivoting the camera carrier from the first orientation to the second orientation as the saddle is being urged from the first to the second position.
5. Apparatus as claimed in Claim 4 in which the operating means for pivoting the camera carrier between the first and second orientations comprises a cam follower co-operable with a cam, one of the cam and cam follower being located on the camera carrier, and the other being rigidly coupled to the guide means.
6. Apparatus as claimed in Claim 5 in which the cam follower is located on the camera carrier.
7. Apparatus as claimed in Claim 5 or 6 in which the cam defines an elongated camming surface extending parallel to the guide means and being shaped for co- operating with the cam follower for pivoting the camera carrier between the first and the second orientations.
8. Apparatus as claimed in any of Claims 5 to 7 in which the cam defines a first elongated camming surface segment extending parallel to the guide means for retaining the camera carrier in the first orientation, and a second camming surface segment stepped from the first camming surface segment and extending parallel to the guide means for retaining the camera carrier in the second orientation, and an intermediate camming surface segment extending between and joining the respective first and second camming surface segments and extending at an angle less than 90 relative to the respective first and second camming surface segments
9. Apparatus as claimed in Claim 8 in which the intermediate camming surface segment extends relative to the first and second camming surface segments at an angle of approximately 45 .
10. Apparatus as claimed in any of Claims 3 to 9 in which the camera carrier is pivotal through an angle of approximately 90 between the first and second orientations.
11. Apparatus as claimed in any of Claims 4 to 10 in which the first support means supports the object card above the camera support means for viewing along a substantially vertically extending axis, and the operating means locates the camera carrier in the first orientation with the central axis of the lens of a camera under test extending substantially vertically and perpendicularly to the object card when the saddle is in the first position.
12. Apparatus as claimed in any of Claims 4 to 11 in which the second support means supports the alignment test means for viewing along a substantially horizontal axis, and the operating means locates the camera carrier in the second orientation with the central axis of the lens of a camera under test extending substantially horizontally and perpendicularly to the alignment test means when the saddle is in the second position.
13. Apparatus as claimed in any of Claims 2 to 12 in which a releasable securing means is provided for releasably securing a camera under test in the camera carrier.
14. Apparatus as claimed in any preceding claim in which a first retaining means is provided for retaining the camera support means in the first position, and a second retaining means is provided for retaining the camera support means in the second position.
15. Apparatus as claimed in any preceding claim in which the camera support means is slideable on the guide means between the first and the second positions.
16. Apparatus as claimed in any preceding claim in which the guide means comprises an elongated guide track for guiding the camera support means between the first and the second positions.
17. Apparatus as claimed in any preceding claim in which the alignment test means comprises a pair of spaced apart first alignment elements, and a pair of spaced apart second alignment elements, the respective first and second alignment elements being provided on the second support means, the first alignment elements being located equi-spaced apart from and on opposite sides of a central focus point on the second support means along a first axis, and the second alignment elements being located equi-spaced apart from and on opposite sides of the central focus point along a second axis, the second axis extending substantially perpendicularly to the first axis, so that when the camera support means is in the second position with a camera under test of ideal field of view angle and alignment aligned with the central focus point, the respective first and second alignment elements should appear at the edge of an image thereof formed by the lens on a photosensitive medium in the camera under test.
18. Apparatus as claimed in Claim 17 in which the spacing of the second alignment elements from the central focus point is substantially similar to the spacing of the first alignment elements from the central focus point.
19. Apparatus as claimed in Claim 17 or 18 in which the alignment test means further comprises a pair of spaced apart third alignment elements, and a pair of spaced apart fourth alignment elements, the third alignment elements being provided on the first support means equi-spaced apart from and on opposite sides of the central focus point along the first axis, and the fourth alignment elements being provided on the second support means equi-spaced apart from and on opposite sides of the central focus point along the second axis, so that when the camera support means is in the second position with a camera under test of ideal field of view angle and alignment aligned with the central focus point, the respective third and fourth alignment elements should appear at the edge of an image thereof formed by the lens on the photosensitive medium of the camera under test.
20. Apparatus as claimed in Claim 19 in which the spacing of the third alignment elements from the central focus point is greater than the spacing of the first alignment elements from the central focus point.
21. Apparatus as claimed in Claim 19 or 20 in which the spacing of the fourth alignment elements from the central focus point is greater than the spacing of the third alignment elements from the central focus point.
22. Apparatus as claimed in any of Claims 19 to 21 in which the alignment test means comprises a first elongated carrier member and a second elongated carrier member, the first and second carrier members being arranged in cruciform formation, the third alignment elements being carried on the first carrier member and the fourth alignment elements being carried on the second carrier member.
23. Apparatus as claimed in Claim 22 in which the respective first and second carrier members are of arcuate shape in respective directions extending along the corresponding ones of the first and second axes.

is
24. Apparatus as claimed in Claim 23 in which the radius of curvature of the first carrier member is slightly greater than the radius of curvature of the second carrier member.
25. Apparatus as claimed in any of Claims 19 to 24 in which each third and fourth alignment element is provided by a corresponding third and fourth alignment band extending transversely of the corresponding first and second axes.
26. Apparatus as claimed in Claim 25 in which the third and fourth alignment bands are of substantially similar width.
27. Apparatus as claimed in Claim 25 or 26 in which the third and fourth alignment bands are of width in the range of 5mm to 15mm.
28. Apparatus as claimed in Claim 27 in which the third and fourth alignment bands are of width approximately 10mm.
29. Apparatus as claimed in any of Claims 17 to 28 in which the first alignment 2g elements are carried on the first carrier member, and the second alignment elements are carried on the second carrier member.
30. Apparatus as claimed in any of Claims 17 to 29 in which each first and second alignment element is provided by a corresponding first and second alignment band extending transversely of the corresponding first and second axes.
31. Apparatus as claimed in Claim 30 in which the first and second alignment bands are of substantially similar width.
32. Apparatus as claimed in Claim 30 or 31 in which the first and second alignment bands are of width in the range of 5mm to 15mm.
33. Apparatus as claimed in Claim 32 in which the first and second alignment is bands are of width approximately 10mm.
34. Apparatus as claimed in any of Claims 19 to 33 in which a plurality of spaced apart intermediate alignment elements are provided on the second support means located between and spaced apart from each first alignment element and the corresponding adjacent third alignment element along the first axis, and between and spaced apart from each second alignment element and the corresponding adjacent fourth alignment element along the second axis.
35. Apparatus as claimed in Claim 34 in which each intermediate element is provided by an intermediate band extending transversely of the corresponding one of the first and second axes.
36. Apparatus as claimed in Claim 34 or 35 in which the width of each intermediate band lies in the range of 5mm to 15mm.
37. Apparatus as claimed in Claim 36 in which the width of each intermediate band is approximately 10mm.
38. Apparatus as claimed in any preceding claim in which the second support means comprises a housing defining a hollow interior region, and the alignment test means is located in the hollow interior region, a communicating opening being provided through the housing to the hollow interior region for providing visual access to the alignment test means by a camera under test when the camera support means is in the second position co-operating with the housing for focusing the camera under test on the alignment test means.

Jo
39. Apparatus as claimed in Claim 38 in which a first light source is located in the hollow interior region of the housing for testing the ability of a camera under test to adjust to changes in light intensity.
40. Apparatus as claimed in any preceding claim in which the object card is provided mounted on the first support means, and the object card comprises a plurality of locations, the locations carrying respective patterns for testing corresponding respective functions of the focusing of a camera under test.
41. Apparatus as claimed in Claim 40 in which one of the locations on the object card is provided with a plurality of parallel first focus bands extending in a first direction, another one of the locations on the object card is provided with a plurality of parallel second focus bands extending substantially transversely relative to the direction of the first focus band.
42. Apparatus as claimed in Claim 41 in which another one of the locations of the object card comprises a plurality of parallel third focus bands extending at an angle relative to the first focus bands and the second focus bands.
43. Apparatus as claimed in Claim 42 in which the third focus bands extend at an angle of approximately 45 to the first and second focus bands.
44. Apparatus as claimed in any of Claims 41 to 43 in which another one of the locations comprises a grid pattern formed by fourth and fifth focus bands, the fifth focus bands extending substantially perpendicularly to the fourth focus band.
45. Apparatus as claimed in any of Claims 41 to 44 in which another one of the locations on the object card comprises a plurality of colour focus bands of respective different colours.
46. Apparatus as claimed in Claim 45 in which the respective colour focus bands are of different widths.
47. Apparatus as claimed in any preceding claim in which a glare guard is provided for reflecting light from a camera under test when the camera support means is located in the first position.
48. Apparatus as claimed in any preceding claim in which the apparatus is adapted for testing the focus, alignment and field of view angle of a lens of a digital camera under test.
49. Apparatus as claimed in Claim 48 in which a control circuit is provided for monitoring electronic signals outputted by a digital camera under test in response to the digital camera being sequentially aligned with the object card, the alignment test means and the first light source.
50. Apparatus as claimed in Claim 49 in which the control circuit monitors electronic signals outputted by a digital camera under test which are indicative of images formed by the lens thereof.
51. Apparatus as claimed in any of Claims 48 to 50 in which the apparatus is adapted for testing a CMOS camera.
52. Apparatus for testing the focus, alignment and field of view angle of a lens of a camera, the apparatus being substantially as described herein with reference to - I, and as illustrated in the accompanying drawings.
53. A method for testing the focus, alignment and field of view angle of a lens of a camera in test apparatus, the method comprising the steps of supporting an object card having a focus test pattern thereon on a first support means of the test apparatus so that a camera under test can be focused on the object card for testing the focus thereof, supporting an alignment test means for testing the alignment of the lens of a camera under test and the field of view angle of the lens thereof on a second support means of the test apparatus, supporting a camera under test on a camera support means of the test apparatus, and selectively and alternately locating the camera support means in a first position cooperating with the first support means for facilitating focusing a camera under test on the object card for testing the focus of the lens of the camera under test, and a second position co-operating with the second support means for facilitating focusing a camera under test on the alignment test means for testing the alignment of the lens of the camera under test and the field of view angle of the lens of the camera under test.
54. A method for testing the focus, alignment and field of view angle of a lens of a camera using the apparatus as claimed in any of Claims 1 to 52, the method comprising the steps of supporting an object card on the first support means, placing the camera under test on the camera support means of the apparatus and selectively and alternately locating the camera support means in a first position co- operating with the first support means for facilitating focusing the camera under test on the object card for testing the focus of the lens of the camera under test, and a second position co-operating with the second support means for facilitating focusing the camera under test on the alignment test means for testing the alignment of the lens of the camera under test and the field of view angle of the lens of the camera under test.
55. A method for testing the focus, alignment and field of view angle of a lens of a camera, the method being substantially as described herein with reference to and as illustrated in the accompanying drawings.
56. A camera tested on the apparatus as claimed in any of Claims 1 to 52.
57. A camera as claimed in Claim 56 tested using the method as claimed in any of Claims 53 to 55.
58. A camera as claimed in Claim 56 or 57 in which the focus of the camera is tested.
59. A camera as claimed in any of Claims 56 to 58 in which the alignment of the lens in the camera is tested.
60. A camera as claimed in any of Claims 56 to 59 in which the field of view angle of the lens of the camera is tested.
61. A camera as claimed in any of Claims 56 to 60 in which the camera is a fixed focus camera.
62. A camera as claimed in any of Claims 56 to 61 in which the camera is a digital camera.