Radiation imagery chemistry: process – composition – or product th – Product having sound record or process of making
Reexamination Certificate
2000-04-14
2004-03-30
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Product having sound record or process of making
C430S510000, C430S934000
Reexamination Certificate
active
06713224
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the field of motion picture films, and in particular to a sound recording film and use thereof in recording analog and digital optical sound tracks onto a motion picture film.
BACKGROUND OF THE INVENTION
Motion picture print films, the film that is shown in movie theaters, commonly employ optical sound tracks along at least one edge of the film. The most common optical sound tracks presently in use are analog sound tracks of the “variable area” type wherein signals are recorded in the form of a varying ratio of opaque to relatively clear area along the sound track. During projection of the motion picture images, a light source illuminates the sound track and a photosensor senses the light passing through and modulated by the sound track to produce an audio signal that is sent to amplifiers of the theater sound system.
Digital sound tracks for motion picture films have been more recently introduced, wherein sound information is recorded in a digital format, e.g. comprising small data bit patterns on the film, typically between perforations of the motion picture film (e.g., Dolby™ Digital Stereo sound tracks) or along the film edge (e.g., Sony™ Dynamic Digital Sound sound tracks). U.S. Pat. Nos. 4,600,280 and 4,461,552, e.g., disclose methods in which digital audio is photographically recorded on motion picture film. U.S. Pat. No. 4,553,833 discloses a method for photographic recording of characters and symbols wherein a light emitting diode array is focused through converging lenses to focus small dot patterns on the film. European Patent Publication EP 0 574 239 discloses method and apparatus for photographically recording digital audio signals with error correction capability on more than one channel. European Patent Publication EP 0 574 136 discloses method and apparatus for recording digital information for clocking tracking error detection and correction, digital audio multichannel tracks and analog audio on a film media.
While digital sound tracks offer the advantage of high quality digital sound recording, they require the use of special sound decoding equipment during projection which all movie theaters may not have. Accordingly, conventional analog sound tracks are typically also included on a motion picture print film which is printed with a digital sound track so that such print film may be distributed to theaters which do not have equipment capable of decoding the digital sound track as well as those that do. Also, as digital sound tracks record information in the form of very small data bits, they may suffer from poor encoding and recording efficiency associated with the high precision demands of the recording process, as well as data loss due to scratches, etc. While various error detection and correction methods have been proposed for such digital sound tracks, analog sound tracks are still nevertheless desirably included on the print films as backups for the digital sound tracks during projection of a film.
In order to optimize the visual quality of the motion picture image as well as the sound quality of the sound track recorded on a motion picture print film, the motion picture and sound track are first typically captured or recorded on separate photosensitive films as negative images, and the resulting negatives are then printed in synchronization on the motion picture print film to form positive images. Because of very short exposure times which must be given to each separate picture, or frame, in capturing a motion picture image, a camera negative film employing relatively fast silver halide emulsions is typically used to record the motion picture images (e.g., Eastman Color Negative and Kodak Vision Color Negative films). In order to reproduce the wide ranges of colors and tones which may be found in various images, the camera film typically also has a relatively low contrast or gamma. Variable area analog sound tracks and digital sound tracks, however, are best recorded with high contrast, relatively slow speed black and white films (e.g., Eastman Sound Recording Films) in order to generate desired sharp images for the sound recording and minimize background noise generated by relatively high minimum densities typically associated with relatively fast films.
Typical black and white sound recording films designed for recording analog sound tracks comprise a relatively fine grain (e.g., grain size less than 0.35 micron) monodispersed silver halide emulsion, which provides the high contrast (e.g., contrast overall gradient greater than 3.7) desirable for recording the sound track with sharp edges. Sharpness is further enhanced in sound recording films by using halation protection. Halation protection is conventionally accomplished in current sound recording films by using a gray-tinted support, or by including an anti-halation layer containing permanently colored dyes, to yield a neutral density. The neutral density resulting from such halation protection increases the minimum density (Dmin) of current sound films by 0.2 density units.
Sound performance is ultimately measured on the print film because that is the vehicle for transmitting the sound film information to the amplifiers in the theater. Common sound systems for reading analog sound tracks incorporate a photodiode in the projector. The photodiode's radiant sensitivity peaks at approximately 800-950 nm (depending on the photodiode type), allowing it to detect predominantly infra-red (IR) radiation emitted by common tungsten lamps. In order to provide effective modulation of common projector illumination light, the optical analog sound track is typically formed in a color motion picture print film by printing the sound track with green and red light to expose the green- and red-light sensitive layers of the color print film, and then specially processing the optical analog sound track area of the print film differently from the picture image frame area such that a silver image is present in the sound track area of the film in addition to the formed magenta and cyan image dyes. The silver image has good detection in the IR, but the special treatment of the sound track area does add complexity to the photo-processing of the color print film. The photo-process is described in Kodak Publication No. H-24, The Kodak ECP-2B Process, Manual for Processing Eastman Color films, referenced above. Various other techniques are also known for retaining silver in the sound track area, e.g., as set forth in U.S. Pat. Nos. 2,220,178, 2,341,508, 2,763,550, 3,243,295, 3,705,799, 4,139,382.
In order to avoid the need for special development of the sound track in a color print film processing operation, it has been suggested to form silverless, dye-only sound tracks, to be used in combination with an appropriate decoding apparatus. For improved performance for such dye-only sound tracks, it may be preferable to record and develop the sound track in a single photosensitive layer of the print film, and recover the signal from the dye-only sound track using a narrow band (10-30 nm bandwidth) light source, the wavelength of which is chosen so as to coincide with the peak absorbance wavelength of the sound track dye. Where the cyan layer of the print film is used to record the sound track, e.g. a narrow band red light source would be used for reading the cyan dye. A red light emitting diode may be conveniently used for reading the cyan dye-only sound tracks, e.g. as has been proposed by Dolby Laboratories in an announcement at the Association of Cinema and Video Laboratories (ACVL) Jun. 1-3, 1995 convention at Lake Tahoe, Nev. The use of such relatively monochromatic light sources for the sound track reader in combination with a single layer dye sound track maximizes the relative optical density difference between the dyed areas and the undyed transparent areas of the sound track while maintaining high contrast. While a conventional tungsten light source may perform poorly with a dye only sound track due to the relatively low signal generated in the solar cell of the s
Dupont Jean-Fabien
Hill Susan D.
Sinn Vicky
Anderson Andrew J.
Huff Mark F.
Walke Amanda C.
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