Image reading device and method for controlling image reading device

1. An image reading device comprising:

a document stage on which a document to be read is placed;

a carriage that includes a lamp radiating light toward the document and the document stage during document reading;

a moving mechanism that moves the carriage, during document reading, from one to an other of two opposite sides of the document stage in a sub scanning direction;

an image sensor that reads the document based on light from the lamp while the carriage is moving from the one to the other side;

an image data generation circuit that generates read image data based on an analog image signal fed out from the image sensor; and

a controller that

turns on the lamp after document reading is started, while the carriage is moving from the one to the other side,

senses an edge of the document in read image data generated while the carriage is moving,

recognizes, while the carriage is moving, based on a result of sensing of the edge, that reading of one placed sheet of the document is completed,

makes the moving mechanism stop movement of the carriage on recognizing once or a plurality of times that the reading of a sheet of the document is completed, and

turns off the lamp to end reading by the image sensor when the carriage is stopped.

2. The image reading device according to claim 1 , further comprising:

an operation panel that accepts setting of a set number of sheets in a document to be placed on the document stage,

wherein

the controller

counts a number of times that the controller recognizes that the reading of one placed sheet of the document is completed while the carriage is moving, and

makes the moving mechanism stop the movement of the carriage when a count value of the number of times becomes equal to the set number of sheets.

3. The image reading device according to claim 2 , wherein

the operation panel accepts setting of a size of a reading range, and

if the count value at a time when a range of a set size has been read is smaller than the set number of sheets,

the controller makes the moving mechanism stop the carriage when the reading of the range of the set size is completed.

4. The image reading device according to claim 2 , wherein

when the operation panel has accepted no setting of a size of a reading range, and

if the count value at a time when a range of a maximum size that can be read has been read is smaller than the set number of sheets,

the controller makes the moving mechanism stop the carriage when the reading of the range of the maximum size is completed.

5. The image reading device according to claim 3 , wherein

when the operation panel has accepted no setting of a size of a reading range, and

if the count value at a time when a range of a maximum size that can be read has been read is smaller than the set number of sheets,

the controller makes the moving mechanism stop the carriage when the reading of the range of the maximum size is completed.

6. The image reading device according to claim 1 , wherein

a home position of the carriage is previously determined,

the home position

is arranged at such a position that a position of a reading line is outside the document stage, and

is a position closer to the one than to the other side, and

when the movement of the carriage from the one to the other side is stopped,

the controller makes the moving mechanism move the carriage to the home position.

7. The image reading device according to claim 1 , wherein

the controller

senses a closed edge to recognize an outline of the document, and

recognizes that the reading of one placed sheet of the document is completed on recognizing the outline.

8. The image reading device according to claim 1 , further comprising:

an operation panel that accepts choice of an edge sensing mode or a normal mode,

wherein

when the edge sensing mode is chosen,

the controller

senses the edge of the document in the read image data generated while the carriage is moving,

recognizes, while the carriage is moving, based on the result of sensing of the edge, that the reading of one placed sheet of a document is completed, and

makes the moving mechanism stop the movement of the carriage on recognizing once or a plurality of times that the reading of a sheet of the document is completed, and

when the normal mode is chosen,

the controller

does not sense, while the carriage is moving, the edge of the document in the read image data generated.

9. A method for controlling an image reading device, comprising:

placing a document to be read on a document stage;

radiating light toward the document and the document stage by use of a lamp during document reading;

moving a carriage including the lamp, during document reading, from one to an other of two opposite sides of the document stage in a sub scanning direction;

reading the document by use of an image sensor based on light from the lamp to generate read image data while the carriage is moving from one to the other side;

keeping on the lamp after document reading is started, while the carriage is moving from one to the other side;

sensing an edge of the document in the read image data generated while the carriage is moving;

recognizing, while the carriage is moving, based on a result of sensing of the edge, that reading of one placed sheet of a document is completed;

stopping movement of the carriage on recognizing once or a plurality of times that the reading of a sheet of the document is completed; and

turning off the lamp to end reading by the image sensor when the carriage is stopped.