GB2335818A

GB2335818A - Film scanner

Info

Publication number: GB2335818A
Application number: GB9906760A
Authority: GB
Inventors: Rainer Kaus
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 1998-03-25
Filing date: 1999-03-25
Publication date: 1999-09-29
Anticipated expiration: 2019-03-25
Also published as: GB2335818B; DE19813125A1; JP2000049991A; GB9906760D0

Abstract

In a film scanner comprising alight source for illuminating sprocket holes of a film to be scanned, and an optical scanner for scanning the illuminated sprocket holes, an optical diverting device 11 is provided, by means of which the image of the sprocket holes can be projected beyond the range of the guiding element, so that the sensor for scanning the sprocket hole can be arranged some distance away from the film scanning head.

Description

1

DESCRIPTION

FILM SCANNER 2335818 The invention relates to a film scanner comprising a light source for illuminating sprocket holes of a film to be scanned, and an optical scanner for scanning the illuminated sprocket holes.

In film scanners, the sprocket holes of a film are often optically scanned for deriving correction signals to control the transport speed or the frame io position. For example, US patent 4,855,836 discloses a film scanner in which a further arrangement for optically scanning the sprocket holes of the film is arranged proximate to an arrangement for optically scanning the film frames.

In this film scanner, the arrangement for optically scanning the sprocket holes comprises both a light source for incident light illumination of the sprocket holes and an optical scanner for scanning the sprocket holes. The film is guided by means of a roll having guidance pins on its sides.

Ideally, the sprocket holes which were used in the pick-up camera for positioning the film frame, should be scanned when scanning sprocket holes.

In the majority of film material to be scanned, this is the pair of sprocket holes preceding the film frame and generally denoted as Mitchell holes. Since the Mitchell holes are particularly very proximate to the film frame to be scanned, a direct scanning of the Mitchell holes has special difficulties. Frequently, there is no place left to provide an illumination source or a camera for scanning the Mitchell holes, because it is exactly in this area where the film frame is guided by guiding elements for mechanically improving the frame position. Arranging illumination sources and sprocket hole scanners at this position may also be obstructed by the film scanning head which is used for scanning the film frame.

It is an object of the invention to provide a film scanner in which the sprocket holes can be scanned proximate to the relevant scanned frame.

This invention provides a film scanner comprising a light source for illuminating sprocket holes of a film to be scanned, and an optical scanner for scanning the illuminated sprocket holes, including an optical diverting device.

2 By means of such a diverting device, the image of the sprocket hole is projected beyond the range of the guiding element, so that the sensor for scanning the sprocket hole can be arranged some distance away from the film scanning head. Since such an optical diverting device can be implemented in a considerably smaller form than a sensor suitable for scanning the sprocket hole, only minimal limitations are to be taken into account in the construction of the film scanning head or the overall film scanner in view of scanning the sprocket holes. Optionally, the optical diverting device may also be used for illuminating the sprocket holes.

This implementation provides the advantage that the light source for illuminating the sprocket hole(s) and the sensor for scanning the sprocket hole(s) can be arranged at substantially any arbitrary position of the film scanner, in a position in which it is least disturbing.

For example, mirrors or prisms are suitable as optical diverting devices.

These and other features and advantages of the invention will be apparent from the following description of an embodiment of the invention, by way of example, with reference to the accompanying drawings, in which-

Figure 1 shows a film scanner according to the invention.

In the embodiment, a film 1 is continuously scanned in a film scanner. To this end, the film 1 to be scanned is driven by means of a capstan 2 and passed between an illumination source 3 for transilluminating the film frame and a frame sensor 4. In this embodiment, illumination source 3 and frame sensor 4 constitute an integral unit which will hereinafter be referred to as scanning head. Due to the integration of illumination source 3 and frame sensor 4, this unit may be exchanged in one piece for another scanning head used to scan, for example a different film format.

For guiding the film 1 within the scanning head 3, 4, the film 1 runs along a curved path on a film carrier device 5. This path is enforced by means of arcuate guiding elements 6 engaging the film outside the film frames and along which the film glides.

3 In the embodiment shown in Figure 1, only one of the two sprocket holes concerned is scanned for correcting vertical and horizontal steadiness errors. To illuminate the sprocket hole, infrared light is used in the embodiment which, surprisingly, images the edges of the sprocket holes with a particularly high contrast. This infrared light is generated by means of an infrared diode 7.

The infrared diode 7 is loosely coupled to an optical waveguide 8 which guides the light of the infrared diode to recesses 9 within the arcuate guiding elements 6. The recesses 9 are closed by means of an optically transparent covers 10 so that the recesses 9 are not contaminated by dirt caused by film abrasion. In io this way, the guiding elements 6 can be implemented completely freely for an optimum film travel without constructive restrictions in favor of illuminating the sprocket holes.

An optical diverting device by means of which the image of the sprocket hole concerned is guided to a spatially offset line camera 14 is arranged above the exit face of the infrared light. In the embodiment, this optical diverting device consists of an adjustable mirror 11 which is fixed to a supporting rod 12 which in turn is secured by means of a holding device 13 arranged outside the scanning head.

In the embodiment, the supporting rod 12 is made of a round rod whose outer surface is milled in the form of a segment on its longitudinal side. In this way, the round rod may be displaced in the longitudinal direction and slid free from rotation into a corresponding prepared recess of the holding device and, for example, detachably connected to the holding device 13 by means of a screw which is not shown for the sake of clarity. Before exchanging the optical scanning head 3, 4, the supporting rod 12 together with the diverting mirror 11 can be removed after disengaging the screw. After a scanning head 3, 4 has been arranged again, the supporting rod is slid into its holding device and the screw is tightened. Due to the rotationally secure implementation of the supporting rod 12, the supporting rod 12 and the diverting mirror 11 rigidly connected to the supporting rod need only be adjusted by axial displacement after the supporting rod 12 has been placed in the holding device 13.1 an adjustment with respect to other spatial axes is not necessary.

4 To detect two sprocket holes, it is possible to use two separate line cameras, with the optical diverting device projecting the images of both sprocket holes outside the range of the scanning head 3, 4. Since suitable line cameras are, however, expensive and should also be adjusted accordingly, in the preferred embodiment the single line camera 14 is preceded by a prism 16 by means of which the two images of the facing sprocket holes are imaged on the one line camera 14.

In the embodiment described hereinbefore, the illumination of the sprocket holes through the film carrier device 5 and scanning by means of an optical diverting device 11 has been described. Dependent on a particular implementation of the film scanner, an arrangement may also be useful in individual cases in which the sprocket holes are illuminated from above via the diverting device 11 and the image of the sprocket hole(s) is applied to the optical scanning sensor through the optically transparent area of the guiding element, for example, also via a further optical diverting device arranged inside or below the film carrier device 5.

From reading the present disclosure, other modifications will be apparent to persons skilled in the art. Such modifications may involve other features which are already known in the design and use of optical film scanners and component parts thereof and which may be used instead of or in addition to features already described herein. Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present application also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation of one or more of those features which would be obvious to persons skilled in the art, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. The applicants hereby give notice that new claims may be formulated to such features andlor combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claims

1. A film scanner comprising a light source for illuminating sprocket holes of a film to be scanned, and an optical scanner for scanning the 5 illuminated sprocket holes, including an optical diverting device.

2. A film scanner as claimed in claim 1, in which the diverting device is adjustable.

3. A film scanner as claimed in claim 2, in which the optical diverting device comprises a mirror or a prism.

4. A film scanner substantially as described herein with reference to the accompanying drawings.

5. Any novel feature or novel combination of features disclosed herein either implicitly or explicitly whether or not it relates to the same invention as that claimed in any preceding claim.