# US 5,705,806 A · Image reading apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,806 A - Document ID: US5705806A - Status: Granted - Kind: A - Application number: 08/827,777 - Filed: 1997-04-11 - Granted: 1998-01-06 - Earliest claimed: 1994-03-14 - Assignees: Minolta Co., Ltd. - Inventors: Shinya Matsuda; Koichi Kamon - Web page: https://patentgrep.com/patent/US5705806A ## CPC - H04N 1/482: {using the same detector device sequentially for different colour components} - H04N 1/00795: {Reading arrangements (details of scanning heads H04N1/024; scanning arrangements therefor H04N1/04)} - H04N 1/1013: {with sub-scanning by translatory movement of at least a part of the main-scanning components (H04N1/107 takes precedence)} - H04N 1/193: using electrically scanned linear arrays {, e.g. linear CCD arrays} - H04N 2201/0416: Performing a pre-scan - H04N 2201/0434: specially adapted for scanning pages of a book - H04N 2201/0436: Scanning a picture-bearing surface lying face up on a support (H04N2201/0434 takes precedence; using cylindrical picture bearing surfaces H04N1/06; with manual scanning H04N1/107) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An image reading apparatus for reading documents disposed face upward on a document platen by optical scanning. The image reading apparatus comprises a color correction filter which has characteristics for shielding light of visible light range and is inserted into said imaging system on prescanning to detect the height of the document. ## Claims ### Claim 1 An image reading apparatus for reading documents disposed fare upward on a document platen by optical scanning, said image reading apparatus comprising: an imaging system which includes an imaging sensor and an imaging lens for forming an optical image of the document on said imaging sensor; a color correction filter which has characteristics for shielding light of visible light range including red, green, and blue color; and a driver which selectively inserts said color correction filter into said imaging systems. ### Claim 2 (depends on 1) An image reading apparatus as claimed in claim 1, wherein said color correction filter has characteristics for shielding light having a wavelength of 700 nm or less. ### Claim 3 (depends on 1) An image reading apparatus as claimed in claim 1, further comprising a controller which executes prescanning operation prior to main scanning operation and actuates said driver to insert the filter into the imaging system in said prescanning operation. ### Claim 4 An image reading apparatus for reading documents by optical scanning, said image reading apparatus comprising: an imaging system which includes a line sensor and an imaging lens for forming an optical image of the document on said line sensor; a color correction filter which has characteristics for shielding light of a predetermined wavelength; a mode selecting means for selecting one from a plurality of imaging modes, each of said modes being provided based on the type of the document; and a driver which selectively inserts said color correction filter into said imaging system based on the result of the mode selection. ### Claim 5 (depends on 4) An image reading apparatus as claimed in claim 4, wherein said color correction filter shields red color light above a wavelength of 600 nm. ### Claim 6 (depends on 4) An image reading apparatus as claimed in claim 4, wherein said selecting means includes a key for selecting one from a plurality of imaging modes. ### Claim 7 (depends on 5) An image reading apparatus as claimed in claim 5, further comprising the mode selecting means selects a text image mode and a photographic mode; and a controller which actuates said driver when said text image mode is selected. ### Claim 8 (depends on 5) An image reading apparatus as claimed in claim 5, further comprising a second color correction filter which has characteristics for gradually shielding light above a wavelength of 550 nm, said second color correction filter is inserted in the photographic mode. ### Claim 9 An image reading apparatus comprising: an imaging element for reading a document; an imaging lens for forming an optical image of the document on said imaging element; color correction means for changing the spectral characteristics of the optical image, said color correction means including a first filter having characteristics for shielding light of a predetermined wavelength and a second filter having characteristics for shielding light of wavelength different from that of said first filter; and a control means for controlling said color correction means based on the type of the document. ### Claim 10 An image reading method for reading documents disposed face upward on a document platen by optical scanning, said method comprising; a first step of scanning a document with a first filter for produce document height data which are used to align the focal point and correct image distortion; a second step of changing the first filter into a second filter, said second filter having a characteristics different from that of the first filter; and a third step of scanning a document with the second filter for produce document image. ### Claim 11 (depends on 10) An image reading method as claimed in claim 10, wherein said second filter is selected from a plurality of filters based on imaging mode. ### Claim 12 (depends on 10) An image reading method as claimed in claim 10, wherein said first filter has characteristics for shielding light of visible light range. ### Claim 13 (depends on 10) An image reading method as claimed in claim 10, wherein said second filter has characteristics for gradually shielding light above a wavelength of 550 nm. ### Claim 14 (depends on 10) An image reading method as claimed in claim 10, wherein said second filter has characteristics for gradually shielding light above a wavelength of 550 nm. ### Claim 15 (depends on 10) An image reading method as claimed in claim 10, wherein said first filter has characteristics for shielding light having a wavelength of 700 nm or less. ### Claim 16 An image reading apparatus for reading documents comprising; an imaging system which reads images from a document via scanning by a sensor during a main scanning operation; a first color correction filter which has characteristics for shielding light of visible light range including red color, green color, and blue color; a start key for starting a reading operation; and a controller for executing a prescanning operation with said first color correction filter prior to the main scanning operation in a response to signal from the start key to measure the height of a document. ### Claim 17 (depends on 16) An image reading apparatus as claimed in claim 16, further comprising a second correction filter which has characteristics for shielding light above a wavelength of 600 nm, wherein said controller executes the main scanning operation with said second correction filter. ### Claim 18 (depends on 16) The image reading apparatus of claim 16 further including a second color correction filter for gradually shielding light above a wavelength of 550 mm, whereby the controller can insert the second color correction filter into the imaging system for the entire main scanning operation. ### Claim 19 (depends on 18) The image reading apparatus of claim 18 further including a third color correction filter for shielding light above a wavelength of 600 mm, whereby the controller can insert the third color correction filter into the imaging system for the entire main scanning operation. ### Claim 20 An image reading apparatus for prescanning documents to determine height data of a document to determine imaging conditions and subsequently for reading images from the document during a main scanning operation comprising: support means for supporting a document to be read; a sensor member; an imaging system for realizing an image of the document in the sensor member; a color correction filter assembly including a first filter for shielding light in the red, green, and blue color range of a visible light spectrum to enhance measurement of height data, a second filter for transmitting light in the visible light spectrum to enhance a photographic image and a third filter for transmitting light in visible light spectrum to enhance a printed text image, the filter assembly is positioned between the support means and the sensor member for selectively inserting a filter into the imaging system; and control means for selectively inserting the first filter into the imaging system during a prescan mode of operation for a measurement of height data and subsequently removing the first filter and inserting one of the second filter and the third filter during a main scanning mode of operation. ### Claim 21 (depends on 20) The image reading apparatus of claim 20 wherein the first filter shields light having a wavelength of 700 mm or less. ### Claim 22 (depends on 21) The image reading apparatus of claim 21 wherein the second filter gradually shields light above a wavelength of 550 mm. ### Claim 23 (depends on 22) The image reading apparatus of claim 22 wherein the third filter shields light above a wavelength of 600 mm. ### Claim 24 An image reading apparatus for prescanning documents to determine height data and for reading images from documents during a main scanning operation comprising: support means for supporting a document to be read; a sensor member; an imaging system for realizing an image of the document in the sensor member; a color correction filter assembly including a first filter for shielding light in the red, green, and blue color range of a visible light spectrum to enhance measurement of height data and at least a second filter for transmitting light in the visible light spectrum, the filter assembly positioned is between the support means and the sensor member for selectively inserting a filter into the imaging system; and control means for selectively inserting the first filter into the imaging system during a prescan mode of operation for a measurement of height data and subsequently removing the first filter and inserting the second filter during a main scanning mode of operation. ### Claim 25 (depends on 24) The image reading apparatus of claim 24 further including a third filter, the second filter is used for imaging in a photographic imaging mode of operation during a main scanning operation while the second filter is used for imaging in a document imaging mode of operation during a main scanning operating.