Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1998-07-22
2001-07-17
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S069000
Reexamination Certificate
active
06263288
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of photographic film scanners, and in particular to film scanners having magnetic read heads for reading magnetically recorded data from the film in conjunction with film scanning.
BACKGROUND OF THE INVENTION
The recently introduced Advanced Photo System (APS) employs a magnetic coating on photographic film for the purpose of magnetically recording data on the film which data provides information concerning associated images exposed onto the film. Film scanners are known which are used to optically scan the images on the processed film to develop digital image data which can be input to a computer to allow storage and manipulation of the image data and digital printing of hard copy prints of the images. Some scanners employ magnetic read heads to permit reading of the magnetically recorded data from the film magnetic layer, the data being stored in the computer memory along with the digital image data for use therewith.
The magnetic layer on this photographic film is virtually transparent which means that the magnetic oxide content is relatively low as compared to traditional magnetic recording media such as video or audio tapes. As a consequence, the magnetic read head and related magnetic signal processing circuits must be very sensitive to detect the relatively low amplitude data signals and must employ significantly high gain factors to raise the detected signals to suitable levels for signal processing. These factors make magnetic data read apparatus in film scanners highly susceptible to external sources of electromagnetic noise.
By the very nature of film scanners connected to computers, particularly in a consumer's home environment, the film scanner is typically located in somewhat close proximity to the computer monitor which is a relatively strong source of electromagnetic noise. Consumer users of film scanners tend not to be cognizant of this problem. If erroneous data reads occur as a result of this electromagnetic interference, the user is likely to be confused and frustrated by the data errors that occur. A known solution to this problem is to provide special electromagnetic shielding around at least the magnetic read head portion of the scanner to absorb the external magnetic fields that the read heads are susceptible to with consequent added bulk and cost. Moreover, the shielding is not always sufficiently effective to protect the scanner, particularly in the case of a scanner placed in very close proximity to the monitor. One known APS film scanner manufacturer attempts to solve this problem by placing a warning notice in the user's manual advising the user not to place the scanner too close to the computer monitor. This has the problem that users notoriously ignore warning notices in a user's manual and, in many cases do not even read the user's manual. Even if the user heeds the printed warning, it is difficult to effectively specify a proper distance that would be effective in all cases. There is therefore a need for a simple, effective and low cost solution to this interference problem when operating a film scanner with magnetic read capability near a computer monitor.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention therefore, there is provided a method of determining that a film scanner having a magnetic read head is in detrimentally close proximity to a source of electromagnetic radiation. The method comprises sensing an output of a magnetic read head in the scanner during a predetermined time period during which film magnetic data transitions are not present at the read head. This can be prior to insertion of the film into the scanner film path or with the film held stationary during the sensing period or by momentarily moving the read head away from the film surface during the sensing period. The method next involves determining from the sensed output the presence of an amount of electromagnetically induced noise that will detrimentally affect detectability of data signal transitions sensed by the magnetic read head; and generating an output indication representative of the fact that the film scanner is detrimentally close to said source of electromagnetic radiation.
In accordance with another aspect of the invention apparatus for determining that a film scanner having a magnetic read head is in detrimentally close proximity to a source of electromagnetic radiation, wherein the apparatus comprises a magnetic read head; a magnetic read head circuit; and a circuit that senses an output of a magnetic read head in the scanner during a predetermined time period during which film magnetic data transitions are not present at the read head. The apparatus of the invention also includes a controller that determines from said sensed output the presence of an amount of electromagnetically induced noise that will detrimentally affect detectability of data signal transitions sensed by the magnetic read head, and a controller that generates, in response to said determination, an output indication representative of the fact that the film scanner is detrimentally close to said source of electromagnetic radiation. The controller functions may be contained within a single microprocessor included within the scanner or entirely within a host computer to which the scanner is connected or the controller functions may be distributed between the host computer and scanner microprocessor.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
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Barbee Manuel L.
Boos, Jr. Francis H.
Eastman Kodak Company
Shah Kamini
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