Registers – Records – Particular code pattern
Reexamination Certificate
2000-02-15
2002-04-02
Lee, Michael G. (Department: 2876)
Registers
Records
Particular code pattern
C235S488000, C235S492000, C235S493000, C235S460000, C235S454000, C235S446000, C235S435000
Reexamination Certificate
active
06364209
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-038525, filed Feb. 17, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
This invention relates to a data reading apparatus adapted to scan and read data such as sound data, image data or text data recorded in the form of optically readable dot codes on a recording medium such as paper.
To date, various devices are known for scanning and reading data such as sound data, image data or text data recorded in the form of optically readable dot codes on a recording medium such as paper.
Of the known data reading apparatus of the type under consideration, those disclosed in U.S. Pat. Nos. 5,896,403 and 5,866,895 are manually operable apparatuses that can read a large volume of data recorded in the form of dot codes on a recording medium such as paper. They represent an innovative technology that could not have been achieved hitherto by means of one-dimensional or two-dimensional bar codes and are feasibly used for recording audio data on a recording medium such as paper and for reproducing audio data from such a recording medium.
According to the U.S. Pat. Nos. 5,896,403 and 5,866,895, a dot code
100
to be used with such an apparatus is basically formed by a plurality of blocks
101
that are arranged two-dimensionally side by side as shown in
FIG. 1
of the accompanying drawings. Each of the blocks includes: a data dot region which is a region where the data to be recorded of the block obtained by dividing the original data concerning a piece of information in the form of sound, image or text is arranged as a dot image (hereinafter referred to as data dot
102
) formed by white dots or black dots representing respective bit values of “0s ” or “1s” and arranged according to a predetermined format; a plurality of pattern dots
103
arranged to show a predetermined positional relationship relative to the data dot region in order to provide reference points for reading the data dots
102
; markers
104
arranged at the four corners of the block, each containing a predetermined number of black dots arranged continuously in succession; and a block address pattern
105
containing a block address and an error detection or error correction sign and arranged along a boundary line separating the block and an adjacently located block so that a plurality of different blocks may be identified when they are read.
With such a dot code
100
, if the dot code extends beyond the field of view of the data reading apparatus or the area that can be picked up by the data reading apparatus with a single shot, the entire original data can be reconstructed from the data contained in the blocks so long all the data dots
102
of each and every one of the blocks
101
are picked up somehow along with the block address (block address pattern
105
) assigned to the block
101
so that a large volume of data may be recorded on and retrieved from a sheet of paper.
Now, the configuration of such a data reading apparatus adapted to read a dot code
100
will be described below.
The data reading apparatus at least comprises: an imaging section including a lighting unit typically containing an LED for illuminating a dot code
100
, an optical system for forming an image of the dot code
100
from the light reflected by the dot code
100
and a solid image pickup element such as CCD for picking up the image formed by the optical system; an image data storage section for converting the signal output from the imaging section for the picked up image into binary data and storing the obtained binary data as image data; a marker detecting section for detecting the markers from the image data stored in the image data storage section; a read reference points determining section for determining read reference points to be used for reading the data dots
102
; a data dot reading section for reading the data dots
102
by referring to the determined read reference points; and a reproduction/output section for reproducing and outputting the restored original data that may be voiced information.
If the markers have the largest diameter equal to the length of five data dots
102
that are arranged linearly and continuously arranged side by side, the number of consecutively arranged data dots
102
is limited (modulated) to less than five. Thus, the marker detecting section detects the markers from the. image data storage section by utilizing this fact and discriminating markers
104
and data dots
102
on the basis of the above threshold.
The read reference points determining section determines a plurality of pattern dot reading points from positions of two adjacently located markers
104
detected by the marker detecting section and related known information (format information) and detects each of the pattern dots
103
by referring to the determined plurality of pattern dot reading points. Then, it computationally determines the read reference point (corresponding to the real center of the marker
104
) by minimizing the value of the error function determined on the basis of the distance from each of the pattern dot reading points and the center of each of the actually detected pattern dots
103
. The data dot reading section divides the gap between any two markers that are located at four corners of each block with lines that are spaced apart by a predetermined distance and reads the pixel value of each of the crossings of the vertical lines and the horizontal lines, or the lattice points, to see if it is black or white.
For the marker detecting section to discriminate markers
104
from data dots
102
and detect the former, it has to use certain parameters including, for instance, a threshold value for the length of a black run that is used for detecting markers
104
. If the threshold value is not set appropriately, the marker detecting section may not be able to detect markers
104
or may mistake data dots
102
for markers
104
to consequently detect may wrong markers. The set of the threshold value is particularly important when the data reading apparatus is designed to read dot codes
1
containing data dots
102
having different sizes.
This will be discussed further by referring to
FIGS. 2A and 2B
.
Referring firstly to
FIG. 2A
, assume here that each data dot
102
has a diameter equal to “1” and data dots
102
are so modulated that there will be no consecutively arranged four dots, whereas each marker
104
has a diameter of “5”. Since data dots
102
are arranged according to the output of the data to be recorded, there may be three consecutively arranged data dots
102
as shown in FIG.
2
A. When detecting markers
104
from an image containing both data dots
102
and markers
104
on the basis of the lengths of black runs, only the black runs of the markers
104
can be detected efficiently without erroneously detecting consecutively arranged data dots
102
by setting “4” for the threshold value for the length of a black run for detecting markers
104
. On the other hand, three consecutively arranged data dots
102
in the image will be detected as candidates for markers if “3” is set for the threshold value for the length of a black run for detecting markers
104
so that a long and tedious process may have to be followed to finally detect correct markers. Meanwhile, it will be appreciated that no markers will be detected if a too large value is set for the threshold value. there may be three consecutively arranged data dots
102
as shown in FIG.
2
A. When detecting markers
104
from an image containing both data dots
102
and markers
104
on the basis of the lengths of black runs, only the black runs of the markers
104
can be detected efficiently without erroneously detecting consecutively arranged data dots
102
by setting “4” for the threshold value for the length of a black run for detecting markers
104
. On the other hand, three consecutively arranged data dots
102
in the image wil
Matsui Akira
Tatsuta Seiji
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Olympus Optical Co,. Ltd.
Walsh Daniel
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