Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-10-20
2003-09-16
Coles, Edward (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S486000, C358S445000, C358S448000, C382S313000, C382S318000
Reexamination Certificate
active
06621598
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color image reader installed on an image data reader such as a hand scanner, and more particularly to a color image reader that reads color image data using a 3-line color sensor.
2. Description of the Related Art
FIG. 16
shows the configuration of a storage-type photoelectric conversion device that reads color images. A 3-line color sensor
100
shown in
FIG. 16
has linear image sensors
102
B,
102
G, and
102
R, each with a plurality of linearly-arranged light receiving cells
101
, arranged in parallel on the board. A blue filter
103
B, a green filter
103
G, and a red filter
103
R are installed on the surface of each cell column.
On an image data reader with a fixed color image reader including the 3-line color sensor
100
, a document containing color images is moved by the transport mechanism, composed of a motor and a transport belt, into the direction perpendicular to the direction in which the cells are arranged on the 3-line color sensor
100
. On the other hand, on an image data reader with a movable color image reader including the 3-line color sensor
100
, the color image reader is moved by the transport mechanism so that the 3-line color sensor
100
can scan a fixed document.
As shown in
FIG. 16
, the linear image sensors
102
B,
102
G, and
102
R are spaced a distance of D equivalent to the distance of a few lines corresponding to the resolution. For example, when the linear image sensors
102
B,
102
G, and
102
R each have a resolution of 300 dpi, when the light receiving cell
101
is 8 &mgr;m ×8 &mgr;m in size, and when the linear image sensors
102
B,
102
G, and
102
R are each spaced a distance equivalent to four lines, D is 32 &mgr;m (that is, 4×8 &mgr;m).
The linear image sensor
102
G reads a part of color images four lines away from the linear image sensor
102
B. Similarly, the linear image sensor
102
R reads a part Of color images four lines away from the linear image sensor
102
G, and the linear image sensor
102
R reads a part of color images eight lines away from the linear image sensor
102
B.
FIG. 17
is a timing diagram showing the output from the linear image sensors
102
R,
102
G, and
102
B when the document moves below the 3-line color sensor
100
one line at a constant speed within one unit of storage time.
FIG. 18
is a diagram showing the read positions on the document. In
FIG. 18
, the document is read from top to bottom and the symbol {circle around (1)} indicates one line.
TG in
FIG. 17
is a transfer gate signal controlling the storage time of images in the 3-line color sensor
100
. As shown in
FIG. 17
, the linear image sensors
102
R and
102
B output, at a specific point in time, the fourth line before, and the fourth line after, the line output by the linear image sensor
102
G, respectively.
That is, as shown in
FIG. 18
, when the linear image sensor
102
G reads nth line, the linear image sensor
102
R reads the (n−4)th line and the linear image sensor
102
B reads the (n+4)th line. In other words, when the linear image sensor
102
G outputs data from the nth line, the linear image sensor
102
R outputs data from the (n−4)th line and the linear image sensor
102
B outputs data from the (n+4)th line. While the linear image sensor
102
G outputs data from the (n−4)th line to the (n+5)th line, the linear image sensor
102
R outputs data from the (n−8)th line to the (n+1)th line and the linear image sensor
102
B outputs data from the nth line to the (n+9)th line.
Therefore, when reading images with the use of the 3-line color sensor
100
shown above, it is required that a positional compensation of ±4 lines be made with respect to the linear image sensor
102
G.
FIG. 19
is a diagram showing how positional compensation is made. For example, data output from the linear image sensors
102
R,
102
G, and
102
B is once stored in the corresponding buffers. When the 3-line color sensor
100
reads data of the nth line, which was output by the linear image sensor
102
G, from the buffer memory, it also reads data, which was output by the linear image sensor
102
R before the period of time equivalent to four lines, from the buffer memory (see the arrow in FIG.
18
). Similarly, the 3-line color sensor
100
reads data, which was output by the linear image sensor
102
B after the period of time equivalent to four lines, from the buffer memory (see the arrow in FIG.
18
). This read method allows the R, G, and B data on the same line to be read at the same time. It should be noted that, instead of controlling the positions of the buffer memory from which data is to be read, the timing of writing data into the buffer memory may be controlled.
When the read speed is constant, positional compensation may easily be performed for R, G, and B data as described above. However, for a color image reader, such as a hand scanner, which does not always scan data at a constant speed, positional compensation may not be performed simply by changing the positions of the buffer memory from which data is to be read.
Consider a case, such as the one shown in
FIG. 20
, in which the read speed is not constant. In
FIG. 20
, the vertical line indicates the distance for which the image reader moves over the read object. Each box in the figure indicates one unit of storage time of the photoelectric conversion device. For example, the box “C(n−6)” in the R column indicates that the image reader moves over two lines within one unit of storage time. In this case, the image reader moves two times faster than it does over “C(n−7)”.
“C(n+x)” indicates image data output by the linear image sensors
102
R,
102
G, and
102
B. In
FIG. 20
, the numeric value (n±x) in each frame indicates, not the number of lines on a read object such as a document, but the number of lines output by the photoelectric conversion device. For example, when the storage time of the photoelectric conversion device is 2 ms, the numeric value indicates the number of lines output every 2 ms.
In this case, the R data and the B data, which are four lines before and after the G data output by the linear image sensor
102
G, cannot be used for positional compensation as for constant speed reading. Instead, as shown in
FIG. 20
, the G data C(n) on the nth line must be made to correspond to the R data C(n−1) on the (n−1)th line and to the B data C(n+2) on the (n+2)th line. That is, the correspondence among the R, G, and B data is not fixed when the reading speed varies randomly.
Disclosed in Japanese Patent Laid-Open Publication No. Hei 8-163316 is a color image reader that performs positional compensation for R, G, and B data by measuring the document transport speed using a rotary encoder provided on the transport mechanism that transports the document to be read. However, the color image reader disclosed in that publication is not designed for variable-speed reading. It only gives the compensation amount for use when the read speed is changed.
As described above, it is difficult for a color image reader installed on an image data reader such as a hand scanner, whose read speed may change during document reading, to appropriately perform positional compensation for R, G, and B data. This problem remains unresolved.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a color image reader performing positional compensation for three colors, R, G, and B, appropriately according to the read speed, to prevent a difference in the three colors caused by the time lag.
The color image reader according to the present invention comprising comprises speed monitoring unit for monitoring a read speed of a read object; and positional compensation unit or circuit for compensating positions of image data of primary colors based on a monitoring result of the speed monitoring unit, the image data being output from the photoelectric conversion means.
The positional compens
Coles Edward
Safaipour Houshang
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