The present invention relates to photographic apparatus, and more particularly to a system for reading a bar code to determine the type of photographic film loaded into such apparatus.
Various photographic apparatus exists that accepts film loaded in cassettes. After loading a new roll of film, the user must change various settings on the photographic apparatus if the film type is different from that previously used. Failure to update the settings will result in improperly exposed images. This can result in a waste of film with a corresponding loss of valuable time. In some instances, the subject matter photographed using incorrect settings may no longer be available, resulting in a loss of the ability to obtain desired photographic images.
A film recorder is an example of photographic apparatus that uses photosensitive film. In a conventional film recorder, a light beam from a cathode ray tube ("CRT") or the like is controlled by a deflection system to scan across a stationary frame of photographic film to expose the film with an image. Typically, the images are generated by a computer for the production of slides, transparencies, photographs, or the like. Alternatively, the images can comprise natural images acquired by a scanner or television camera for subsequent processing by a computer.
Known film recorders, such as those sold under the trademark "SOLITAIRE" by Management Graphics, Inc. of Minneapolis, Minn., U.S.A., typically include a light source such as a CRT for producing a beam, a deflection system for scanning the beam across the face of the CRT, a system control and central processor unit ("CPU") for controlling the deflection system, and a camera (i.e., "film transport"). The latter component includes a film transport body, lens, lens mounting assembly, aperture plate, film plate, and film transport mechanism. An image to be recorded is first written on the phosphor of the CRT by deflecting an electron beam in a raster pattern and modulating the intensity of the beam. This process is analogous to the creation of a television picture. Alternately, the image can be written on the CRT using well known time modulation techniques, wherein the beam intensity is constant but the time the beam is kept at each point is varied depending on the exposure required.
The resulting pattern (the "object image") on the CRT is optically imaged onto photographic film by the film transport, which contains the required optics and mechanism to advance the film to successive frames. Other types of light sources can be substituted for the CRT in a film recorder. Examples include fiber optic sources, lasers, and focussed light impinging a rotating drum wherein one or more rotations are completed for each scan line.
In order for the film recorder to accommodate different film types (e.g., size in millimeters, sprocket hole type and arrangement, film processing type, such as E6, C41, etc.) and speeds (i.e., light sensitivity), specific information is needed about the particular film being exposed. This information is used to properly expose and color balance the image that the film produces when developed. Different films usually have different and distinctive color dyes and spectral sensitivity characteristics which must be correctly exposed by the light sources in the film recorder in order to result in a properly balanced picture. The methods for achieving the exposure control are highly varied and specific to the technology used in the film recorder. The film type and light sensitivity ("speed") are an important piece of information in that control.
If a film recorder permits different types of film to be used, the operator must supply information identifying which film is currently being exposed. This has usually been accomplished through a selection means such as a switch setting. Alternately, the information may be contained in a computer data file downloaded to the film recorder when a new type of film is loaded. If the settings made to the film recorder do not match the actual film loaded in the device, incorrect exposure generally results.
Various techniques are known for informing photographic apparatus about the speed of the film that is loaded. Most 35mm cameras currently on the market contain electrical contacts to identify a painted code formed by insulating paint and bare metal patches ("DX" code) on the film cassette. The DX conductive patch code identifies the speed, roll length, and exposure latitude of the film. The roll length is indicative of the number of frames (frame count) that will be available for exposure on the film. Another technique is to provide notches along an edge of the film that can be felt or sensed. Currently, some cut sheet films contain such notches that identify the film speed and type. Each of the known techniques only provide limited information about the film or require complicated and expensive notch sensors or the like.
It would be advantageous to provide apparatus for automatically determining the exact type, speed, and roll length of film loaded in a photographic device such as a film recorder. It would be further advantageous to provide such apparatus in a film recorder without the need to add a substantial amount of hardware. It would be still further advantageous to provide such apparatus that does not require any user interaction, and performs all required exposure settings automatically after determining the type and speed of film that has been loaded by the operator.
The present invention provides apparatus that enjoys the aforementioned advantages by scanning a DX bar code provided on film cassettes by most film manufacturers in addition to the DX conductive code patch, to determine the exact film type, speed, and roll length.