Image reader capable of detecting blank documents

Claim 2

An image reader comprising: an image sensor for reading an image of a document and converting the image into electrical bit data; scanning optical means for scanning the image of the document and for transmitting the scanned image to the image sensor; binarization means for binarizing the bit data by comparing the bit data from the image sensor with a predetermined threshold value; blank-judging means for comparing the bit data from the image sensor with a predetermined reference value, the predetermined reference value being set to a value that is different from the predetermined threshold value, and judging that the document is blank when the number of bit data having a value over the predetermined reference value does not exceed a preset number that is not equal to 0; and control means for discontinuing the image reading operation in response to the judgment of a blank document.

Claim 3

An image reader as claimed in claim 1, wherein the control means generates a signal representing the existence of a blank document to warn an operator.

Claim 4

An image reader as claimed in claim 1, wherein the control means causes the scanning means to preliminary scan the image of the document while inhibiting the output of the read data to the exterior, and then to execute, a scanning operation for outputting the bit data to the exterior when the blank judging means judges that the document is not blank.

Claim 5

An image reader comprising: a document support table for placing a document thereon; an image sensor reading an image of a document and converting the image into electrical data representative of picture elements; scanning optical means for scanning the image of the document placed on the document support table and for transmitting the scanned image to the image sensor; blank document detecting means for detecting whether the document is blank or not, said detection means comparing the data of each picture element with a predetermined reference value, counting a bit number from the data having a value over the predetermined reference value, and detecting whether a blank document is on the support table when the counted number does not exceed a preset number that is not equal to 0; and control means for preventing a subsequent image reading operation in response to the detection of the blank document.

Claim 6

An image reader comprising: a document support table for placing a document thereon; an image sensor reading an image of a document and converting the image into electrical data representative of picture elements; scanning optical means for scanning the image of the document placed on the document support table and for transmitting the scanned image to the image sensor; blank document detecting means for detecting whether the document is blank or not, said detection means comparing the data of each picture element with a predetermined reference value, counting a bit number from the data having a value over the predetermined reference value, and detecting whether a blank document is on the support table when the counted number does not exceed a preset number that is not equal to 0; and control means for preventing a subsequent image reading operation in response to the detection of the blank document.

Claim 7

An image reader as claimed in claim 4, wherein the control means generates a signal representing the blank document to warn an operator.

Claim 8

An image reader as claimed in claim 4, wherein the control means causes the scanning means to preliminary scan the image of the document wile inhibiting any output of the data to an exterior usage, and then to execute the scanning operation for outputting the bit data to the exterior usage when the blank judging means judges that the document is not blank.

Claim 9

An image reader as claimed in claim 4, wherein the blank document detection means includes a memory capable of storing the data for one line, and an analysis means for analyzing the data which can be read out from the memory in succession.

Claim 10

An image reader as claimed in claim 4, wherein there is provided on the document support table an automatic document feeder which handles the document so as to position a document on the document support table for reading the image thereof and to discharge the same, and the control means controls the automatic document feeder to discharge the document when the document positioned on the document support table is detected as a blank one.

Claim 11

An image reader comprising: an image sensor means for reading an image of a document and converting the image into electrical bit data representative of individual picture elements; optical means for projecting the image of the document to the image sensor; binarization means for binarizing the bit data by comparing the bit data from the image sensor with a predetermined threshold value; blank-judging means for comparing the bit data of each picture element with a predetermined reference value to detect picture elements indicating black color, the predetermined reference value being set to a value that is different from the predetermined threshold value, and judging that the document is blank when the number of picture elements indicating black color does not exceed a preset number that is not equal to 0; and control means for discontinuing the image reading operation in response to the judgment of a blank document.

Claim 12

An image reader comprising: an image sensor means for reading an image of a document and converting the image into electrical bit data representative of individual picture elements; optical means for projecting the image of the document to the image sensor; binarization means for binarizing the bit data by comparing the bit data from the image sensor with a predetermined threshold value; blank-judging means for comparing the bit data of each picture element with a predetermined reference value to detect picture elements indicating black color, the predetermined reference value being set to a value that is different from the predetermined threshold value, and judging that the document is blank when the number of picture elements indicating black color does not exceed a preset number that is not equal to 0; and control means for discontinuing the image reading operation in response to the judgment of a blank document.

Claim 13

An image reader comprising: an image sensor for reading an image of a document and converting the image into electrical bit data comprised of a plurality of data elements; scanning optical means for scanning the image of the document and for transmitting the scanned image to the image sensor; binarization means for binarizing the bit data by comparing the bit data from the image sensor with a predetermined threshold value; blank-judging means for comparing a value of each of the plurality of data elements with a predetermined reference value to determine the number of data elements having a value greater than the predetermined reference value, the predetermined reference value being set to a value that is different from the predetermined threshold value, and judging that the document is blank when the number of data elements having a value greater than the predetermined reference value does not exceed a preset number; and control means for discontinuing the image reading operation in response to the judgment of a blank document.

Claim 14

An image reader comprising: an image sensor for reading an image of a document and converting the image into electrical bit data comprised of a plurality of data elements; scanning optical means for scanning the image of the document and for transmitting the scanned image to the image sensor; binarization means for binarizing the bit data by comparing the bit data from the image sensor with a predetermined threshold value; blank-judging means for comparing a value of each of the plurality of data elements with a predetermined reference value to determine the number of data elements having a value greater than the predetermined reference value, the predetermined reference value being set to a value that is different from the predetermined threshold value, and judging that the document is blank when the number of data elements having a value greater than the predetermined reference value does not exceed a preset number; and control means for discontinuing the image reading operation in response to the judgment of a blank document.