GB2328100A

GB2328100A - Film scanner and/or recorder with multiple film paths

Info

Publication number: GB2328100A
Application number: GB9816231A
Authority: GB
Inventors: Sean Adkins
Original assignee: Imax Corp
Current assignee: Imax Corp
Priority date: 1997-08-01
Filing date: 1998-07-24
Publication date: 1999-02-10
Anticipated expiration: 2018-07-24
Also published as: CA2243436A1; GB9816231D0; GB2328100B

Abstract

Optical apparatus for high speed conversion of digital data to film and for reading film to produce digital data information has a rotatable multifaceted reflector 3 which can move reversibly on an axis of rotation, a light source 5, 7 that provides one or more light beams which are focused by a lens assembly onto the multiple facets of the reflector 3, a plurality of film transporters that move films 5, 6 transversely to the axis of rotation, and a modulator that modulates the light beams in accordance with digital image data.

Description

FX;M ECANNtt AND/OR RECORDER WITS MULTIPLE FILM PATS8 FIELD OF THE INVENTION The present invention relates to an image transfer system incorporating multiple film paths for the high speed conversion of digital data to film and for reading film to produce digital image information.

BACKGROUND OF THE INVENTION In motion picture, television, video, and broadcasting production, high speed scanners have been employed for recording and for reading media for years. A scanner is an optomechanical system that deflects light and/or moves the light in relation to the media to produce motion of a focused spot so that by observing the intensity of the transmitted light information is read and by varying the intensity of the spot information is written. Thus, reading involves using a scanner to recover digital data from a previously exposed media while writing involves exposing media in accordance with digital data.

Internal drum scanners that use lasers for the reading and writing of media are well known in the art. Such scanners are disclosed in U.S. Pat. No. 3,316,348, issued to Hufnagel et al., which discloses a scanner for recording using laser light from a moving aircraft that is reflected from terrain to modulate a second laser beam which exposes phot,ographic Calm; in U.S. Pat. No. 3,465,352, issued to Carlson et al., which discloses a scanner for recording and scanning a document to a microfilm; in U.S. Pat. No.

3,457,422, issued to Rottman, which discloses an optical system with a scanner for scanning an image and rotating it; in U.S. Pat. No. 3,816,652, issued to Barnett, which discloses a laser facsimile transceiver that uses a scanner for reading and writing a document; in U.S. Pat. No.

4,015,081, issued to Starkweather,which discloses a scanning system that uses a modulated and an unmodulated light beam for writing and reading, respectively, with the beam strikiny the same facet of a polygon scanner either at the same location or at spaced apart locations aligned with an axis of the rotating polygon scanner; in U-S. Pat. No. 4,236,183, issued to Howe, which discloses optical configurations for a rotating polygon film scanner; and, in U.S. Pat. No.

3,958,250 which discloses a photographic data plotting system using a modulated laser light that scans a photographic film.

All of the previous devices provide one path for reading or writing. U.S. Pat. No. 2,831,055, issued to Mattke, discloses a film projector capable of scanning multiple films at one time. The Mattke device consists of a scanner composed of an array of plane mirrors arranged around a circle with each mirror mounted on an axis parallel to the axis of the circle. Curved film gates support the film as scanning light passes through it. Since the projector circle is la@@e in comparison to the film gates, a large amount of scanning area is wasted. Besides being cUmb BES, this device also does not provide any means for recording onto film. Moreover, films with different widths are not easily accommodated in this device since a film of a different width would presumably involve dismantling the film gate and substituting another film gate appropriate for the film width.

In the prior art, only 180 degrees or less of the scanning area is used although the internal drum scanner has the capability to scan 360 degrees. Smaller format: film such as motion picture film uses even less of the available scanning area in each rotation of the scanning reflector.

Accordingly, it is the object of this invention to provide an improved image transfer system that uses the scanner reflector more efficiently.

In order to scan diffcrent widths of films, a different path for each size of film must be provided. In conventional apparatus, this means changing the mechanical apparatus of the film path and sometimes the film holding cylinder itself.

This is not desirable since the alignment of the cylinder to the axis of rotation and axis of linear translation of the scanner is set at a very high degree of precision and changing cylinders disrupts this alignment. It is another object of che invention to provide an image transfer system those can reed or white on a wide variety of films with differcnt widths without dismantling the compone Eg of the device.

Furthermore, reading and writing of film require different components. In addition, the film and, thus, the film handling differ in significant ways for reading and writing. Yet: another object of the invention is to provide a dcvice that allows the user an easy way to switch between reading and writing modes.

SUMMARY OF THE INVENTION According to the invention, there is provided an optical apparatus for high speed conversion of digital data to film and for reading film to produce digital data information.

The apparatus is comprised of a scanning reflector that is rotatable about an axis of rotation and that is reversibly translatable in a direction parallel to the axis of rotation.

It includes a light source that emits light beams that are focused by a lens assembly onto the facets of the reflector and a modulator which can modulate a light beam in accordance with digital data so that the light beam records onto a light sensitive film associated with the light beam. It further includes a plurality of film transporters which move film paths in a direct ton transverse to the axis of rotation of the scanner.

The apparatus may have a second modulator which modulates a second light: beam and records ohbO ond film that is light sensitive.

The apparatus may further have a light reader that reads digital information from the intensity of a second light be.lm that passes through an exposed film.

The scanning ref lector may have one or more facets that reflect light beams.

Preferably, there is further provided a cylindrical housing concontric with the axis of rotation of the reflector. Films may be mounted on the inner surface of the cylindrical housing or on the outside of the housing over openings present in the housing. Different frames with different aperture widths may be used to mount films of different widths. The cylindrical housing may have a light impervious chamber and a removable light shield to prevent light from exposing a light sensitive film when another film is being scanned.

BRIEF DESCRXPTZON OF TNE DRAWINGS The novel features believed to charsteris@ the invention are set forth in the appended claims. The invention, itself, however, as well as other features and advantages thereof, will be best understood by reference to the detailed description which follows, read in conjunction with the accompanying drawings, wherein: Fig. 1 is a perspective view of an image transfer system in accordance with a preferred embodiment of the invention; Fig. 2a is a front view of a holding plate for one film; Fig. 2b is a front view of a holding plate for a second film; Fig. 3a is a schematic view of a cylindrical housing with three film paths: Fig. 3b is a schematic view of a cylindrical housing with four film paths; Fig. 4 is an end view of an embodiment of one film being read on two film paths; Fig. 5 is an end view of an embodiment with one light beam and two film paths; Fig. 6 is an end view of an embodiment with two light beams and two film paths; Fig. 7a is an end view of an embodiment for writing on two film paths; Fig. 7b is an end view of an embodiment for reading on two film paths; and Fig, 8 is an end view of an embodiment for reading a film on one film path and writing on another film path.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Fig. 1, there is shown in perspective an image transfer system comprising a light source 57, a laser, from which a light beam 13 is generated. An image lens 12 focuses the beam of light 13 onto the scanning reflector 3 which is mounted on the axis of cylinder 30. Scanning reflector 3 is rotated by scanning motor 7. An optical rotary encoder 11 is affixed to the shaft of the scanning motor 7 in order to indicate its angular position. A translation stage 8 driven by translation drive motor 10 causes linear movement of motor 7 in a forward and reverse direction. A linear encoder 9 provides information as to the axial position of the motor 7 including the scanning reflector 3. Concentric with the axts. at tation of the scanning reflector 3 is a larger cylinder 1 which is used as a support for film while it is read or exposed by the light beam 13 that is being focused by image lens 12 and deflected hy scanning reflector 3. The supporting surface may be any curved shaped other than a cylinder provided that the locus of the focal point is not substantially changed when scanning.

For some purposes, the film may be inside the cylinder 1, in which case, openings 2 are not needed. In this embodiment, two film paths are shown on the outside surface of the cylinder 1. On each side of the cylinder 1, there are two openings 2 to permit the light to pass through the cylinder from the scanning reflector 3 to the films 5 and 6.

For reading and writing on each film, holding plates 35 and 36 serve as a frame around each film 5 and 6 and keep each of the film 5 and 6 in uniform contact with the cylinder 1 over the area to be read or exposed. Referring to Fig. 2a and Fig. 2b, a film 30 has a width that is greater than the width of film 31. The two films use two different holding plates 35 and 36 which have the same overall width 34 that is approximately equal to the width of the opening in the cylinder on which the holding plates are mounted. The holding plates 35 and 36, thus, serve as an adapter that determines the maximum size of the opening 2. The holding plate may alse have an adjustable frame that can be changed to fit the width of the film. An advancing dev dvances the film to the holding plate.

If the film is perforated as in the case of film 6, the perforations may be registered with registration pins (not shown). The registration pins are insertable into the perforations of the film. A device that withdraws the pins from particular perforations in the film at both sides of the opening and another device that provides other pins to engage other perforations in the film may be present. The two devices operating in concert advance the film a fixed number of perforations and therefore a fixed distance. Each film frame thus has a fixed and repeatable position on the film with respect to previous and successive film frames.

In an alternate embodiment, the registration pins are fixed on the film holder or cylinder. Instead of devices that move the pins in and out of film perforations, the film is lifted off the registration pins and advanced a fixed number of perforations and then reset on the registration pins of the holding plate by another device.

Referring to Fig. 3a, the cylinder 1 may also have three openings, thus providing an image transfer system which allows three films 37, 38, 39 to be scanned or it may have four openings as shown in Fig. 3b allowing four films 40, 41, 42, 43 to be scanned. More than four openings are possible also. Each opening in the srlindgr hZ wn means of holding, registering, and advancing the film (not shown).

Referring to Fig. 4, in an alternative embodiment, instead of having two films, only one film 56 may occupy both openings. One section of the film may be threaded through one opening while another section of the same film may be threaded through a second opening with the aid of two rollers 58 and 59. The two films may be scanned concurrently or the slack loop of film 60 can be configured so that one station is scanned while the other advances the film.

Referring to Fig. 5 and Fig. 6, there is shown a view looking into an end of an image transfer system along an axis thereof that the beam of light enters to strike the scanning reflector 3. In Fig. 5, there are two film paths with two films 5 and 6 secured to two openings in the cylinder 3 and one light source (not shown), which emits one light beam 13.

In addition, the scanning reflector 27 is multifaceted, with four facets 28. For each facet 28 there is a focusing lens 26 positioned to focus light reflected from a facet 29 into a focused spot 29 onto the film. The focusing lenses 26 rotate with the scanning reflector 27. Because of the configuration of the facets 28 of the scanning reflector 27 and the focusing lenses 26, the beam of light 13 must be located away from the central axis of the cylinder 1 so that the beam 13 can be deflected onto the sides of the eyS r 1 where the films S and 6 to be read or exposed are positioned, Since only one source of light is present, only one film can be scanned at a time. The selection of which side of the cylinder 1 to scanned is made by a moveable mirror 16. The moveable mirror 16 when placed in location, 14, deflects the light beam 13 allowing it to strike the scanning reflector 27 on the facet 28 suitable for exposing or reading film 6. When moveable mirror 16 is moved to a position, 15, the light beam 13 is deflected towards the facet 28 of the scanning reflector 27 suitable for exposing or reading film 5.

Referring to Fig. 6, a similar arrangement to Fig. 5, with two film paths having two films S and 6 secured to two openings in the cylinder 3, a multifaceted scanning ref lector 27 and focusing lenses 26, is shown. The difference between the two embodiments is that in this embodiment two light sources emitting two independent light beams 19 and 20 are present. The two light sources, in this embodiment, are two separate lasers. In other embodiments, the light source can comprise of a combination of multiple lasers, for e.g. a combination of laser emitting red light, another laser emitting green light and a laser emitting blue light, or light source can simply be a source of white light. In addition, two mirrors 17 and 18, which deflect the light beams 19 and ab to the two appropriate facets 28 of the scanning rcflcctor 27 arc provided. .hU6, lQht beam 20 travels to mirror 18 which deflects light beam 20 towards facet 28 on the scanning reflector 27. Facet 28, furthers, deflects the light beam 20 towards the appropriate focusing lens 26 which focuses light beam 20 onto film 5. Similarly, light beam 19 is deflected by mirror 17 to an opposite facet 28 on the scanning reflector a7. Facet 28, further, deflects the light beam 20 towards the appropriate focusing lens 26 which focuses light beam 19 to film 6.

Referring to Fig. 7a, when the scanning reflector is operating as a recorder for recording digital data on unexposed film 46 and 47 in both film paths, the light beams 48 and 49 are modulated by light modulators 44 and 45 according to digital image data.

Referring to Fig. 7b, when the scanner is operating as a reader of films 52 and 53 rather than a film recorder, scanning light collectors 50 and 51 are present instead of light modulators. The scanning light collector comprises of photodiodes or photomultiplier tubes which collect and detect the intensity of light. The scanning light collector may have additional mirrors to focus light into a small spot at the face of the detectors. In addition, the collector may also have an optical system of mirrors to reflect certain wavelengths of light to photomultipliers so that information about color as well as intensity is collected.

Referring to Fig. 8, there is shown a view looking into the end of the image transfer system along the axis that the beam of light may enter to strike the multifaceted scanning reflector 3. In Fig. 8, there are two film paths with two films 24 and 25 secured to the two openings on the outside of cylinder 1. Film 24 is an exposed and processed film that is to be read while film 25 is an unexposed film that is to be written upon by exposing it to a modulated light beam.

While film 24 is read by the scanning of light by the scanning reflector over the film and onto the scanning light collector and detector, unexposed film 25 is protected by a light tight compartment 22 and removable light shield 23.

The light shield 23 is mechanically removed when film 25 is to be exposed and modulated light beam is scanned with the scanning reflector 3 onto film 25.

While the present invention has been described with particularity, it should be understood that various modifications and alterations may be made therein without departing from the spirit and scope of the invention set forth in the appended claims.

Claims

1. An optical apparatus for high speed conversion of digital data to film and for reading film to produce digital image information, comprising: (a) a rotating scanning reflector reversibly movable in a direction parallel to an axis of rotation of said reflector, said scanning reflector having a number of facets equal to n; (h) a plurality of light sources and a lens assembly for focusing a plurality of spaced apart beams of light onto said scanning reflector; (c) a plurality of film transporters operative to move films in a respective film path in a direction transverse to said axis of rotation at a distance from said reflector substantially equal to a distance to a focal point of said beams of light; (d) a modulator in a path of at least one of said beams of light operative to modulate said one beam of light in accordance with digital image data; wherein the film associated with said one beam of light is light sensitive.

2. Appr-atus accordin@ , claim , wherein another of said beams of light has a modulator in a path thereof and is operative to modulate said another beam of light and the film associated with said another beam is light sensitive and records an image thereon of data used to modulate the modulator.

3. Apparatus according to claim 1, wherein another of said beams of light passes through an associated, exposed film of said films and is incident on a light detector.

4. Apparatus according to claim 1, wherein n equals one.

S. Apparatus according to claim 1, wherein n is greater than one.

6. Apparatus according to claim 1, including a cylindrical housing surrounding said scanning reflector and aligned with an axis of rotation thereof.

7. Apparatus according to claim 6, wherein said films are mounted on an inner surface of said housing.

8. Apparatus according to claim 6, wherein said housing has a plurality of openings at bif\f eid films may be mounted, respectively.

9. Apparatus according to claim 8, including a frame with an aperture of a selected width, said frame affixable to said cylindrical housing over each of said openings and capable of receiving films of substantially similar width to the selected width.

10. Apparatus according to claim 8, including a folding mirror operative to reflect said beams of light to a facet of said scanning reflector.

11. Apparatus according to claim 10, wherein said folding mirror is moveable to a second position and operative to reflect light to a second facet of said light reflector.

12. Apparatus according to claim 8, including a film transport assembly which moves a single length of film through said plurality of openings.

13. Apparatus according to claim 6, further including a detachable light impervious chamber where a light sensitive film is housed preventing light from exposing said lightsensitive film when a second film is being scanned.

14. Apparatus according to claim 6, further including a removable light shield insertable @@@@ns@ to an inner surface of said cylindrical housing, said shield preventing light from exposing a light-sensitive film when a second film is being scanned.

15. An optical apparatus substantially as herein described with reference to the accompanying drawings.