Lost scan line detecting method and device for a handheld scanner having a lost line counter
First Claim
1. A lost scan line detecting method for providing lost scan line information to a computer system which is connected to and which receives scan line picture data from a handheld scanner so as to enable said computer system to derive picture data which corresponds to a lost scan line from available scan line picture data, said handheld scanner generating a series of photo receiver pulses and a series of step trigger signals, each of said photo receiver pulses indicating that said handheld scanner has traveled by a distance which is equivalent to one scan line on a document being scanned, said handheld scanner generating each of said step trigger signals after one of said photo receiver pulses has been generated, the period between two said step trigger signals being constant and corresponding to a predetermined maximum scanning speed of said handheld scanner, said method comprising the steps:
- providing a first counter means to count said photo receiver pulses;
providing a second counter means to count said step trigger signals; and
providing a comparator means to compare count outputs of said first and second counter means and to generate a lost scan line signal whenever said count outputs are unequal so as to indicate to said computer system that a lost scan line condition has occurred.
1 Assignment
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Accused Products
Abstract
A lost scan line detecting device provides lost scan line information to a computer system which is connected to and which receives scan line picture data from a handheld scanner, thereby enabling the computer system to derive picture data which corresponds to a lost scan line from available scan line picture data. The handheld scanner generates a series of photo receiver pulses and a series of step trigger signals. Each of the photo receiver pulses is used to indicate that the handheld scanner has traveled by a distance which is equivalent to one scan line on a document being scanned. The handheld scanner generates each of the step trigger signals after one of the photo receiver pulses has been generated. The period between two step trigger signals is constant and corresponds to a predetermined maximum scanning speed of the handheld scanner. The lost scan line detecting device includes a first counter to count the photo receiver pulses and a second counter to count the step trigger signals. The count outputs of the first and second counters are compared, and a lost scan line signal is generated whenever the count outputs are unequal so as to indicate to the computer system that a lost scan line condition has occurred.
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Citations
9 Claims
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1. A lost scan line detecting method for providing lost scan line information to a computer system which is connected to and which receives scan line picture data from a handheld scanner so as to enable said computer system to derive picture data which corresponds to a lost scan line from available scan line picture data, said handheld scanner generating a series of photo receiver pulses and a series of step trigger signals, each of said photo receiver pulses indicating that said handheld scanner has traveled by a distance which is equivalent to one scan line on a document being scanned, said handheld scanner generating each of said step trigger signals after one of said photo receiver pulses has been generated, the period between two said step trigger signals being constant and corresponding to a predetermined maximum scanning speed of said handheld scanner, said method comprising the steps:
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providing a first counter means to count said photo receiver pulses; providing a second counter means to count said step trigger signals; and providing a comparator means to compare count outputs of said first and second counter means and to generate a lost scan line signal whenever said count outputs are unequal so as to indicate to said computer system that a lost scan line condition has occurred. - View Dependent Claims (2, 3, 4, 5)
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6. A lost scan line detecting device for providing lost scan line information to a computer system which is connected to and which receives scan line picture data from a handheld scanner so as to enable said computer system to derive picture data which corresponds to a lost scan line from available scan line picture data, said handheld scanner generating a series of photo receiver pulses and a series of step trigger signals, each of said photo receiver pulses indicating that said handheld scanner has traveled by a distance which is equivalent to one scan line on a document being scanned, said handheld scanner generating each of said step trigger signals after one of said photo receiver pulses has been generated, the period between two said step trigger signals being constant and corresponding to a predetermined maximum scanning speed of said handheld scanner, said handheld scanner having a data buffer for storing temporarily said scan line picture data prior to retrieval by said computer system therefrom, said data buffer generating a buffer full signal when filled, said lost scan line detecting device comprising:
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a first counter means for counting said photo receiver pulses; a second counter means for counting said step trigger signals, said second counter means being disabled by said buffer full signal from said data buffer; and a comparator means for comparing count outputs of said first and second counter means and for generating a lost scan line signal whenever said count outputs are unequal so as to indicate to said computer system that a lost scan line condition has occurred. - View Dependent Claims (7, 8, 9)
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Specification