Image scanner with optical waveguide and enhanced optical sampling rate

• US 6,414,760 B1
• Filed: 10/29/1998
• Issued: 07/02/2002
• Est. Priority Date: 10/29/1998
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Altunbasak, Yucel, Lopez, Patricia D., Williamson, James B.
• Primary Examiner(s): Grant, II, Jerome
• Assistant Examiner(s): Worku, Negussie
• Application Number:
  US09/182,156
• Time in Patent Office: 1,342 Days
• Field of Search: 358/484, 358/474, 358/482, 358/483, 358/494, 358/496, 358/497, 358/475, 358/509, 385/116, 385/33
• US Class Current: 358/484
• CPC Class Codes: H04N 1/0281 with means for collecting light from a line or an area of the original and for guiding it to only one or a relatively low number of picture element detectors
• CPC Class Codes: H04N 1/192 Simultaneously or substantially simultaneously scanning picture elements on one main scanning line
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays
• CPC Class Codes: H04N 1/1936 using a light guide, e.g. an optical fibre bundle or array
• CPC Class Codes: H04N 2201/0458 Additional arrangements for improving or optimising scanning resolution or quality

Abstract

An optical waveguide and a shutter are used to guide light from multiple illuminated pixels on a document being scanned onto a single photosensor element. Various methods are disclosed for selecting one pixel at a time for projection onto a single sensor element. Multiple scans are required to capture all the image pixels. The data from multiple scans are then combined to form a single scanned image that has a higher optical sampling rate than the native optical sampling rate of the sensor array. Superresolution image analysis techniques developed for reconstruction of one image from a set of lower resolution images may be applied to provide a diffraction-limited high-resolution image. The waveguide as described also provides an ability to reduce scanning time for lower resolution images. In a first example embodiment, a rotating rod lens with a pattern of black and white areas is used to block/unblock optical waveguide array elements. In a second example embodiment, a thin mask is translated over the optical waveguide array elements. In a third example embodiment, an electronic display device such as a liquid crystal array is used to block/unblock optical waveguide array elements.

Claims

1. An image scanner comprising:

an array of photosensor elements;

an optical waveguide suitable for guiding light from pixels on an original image onto the photosensor elements; and

a rotatable cylindrical rod lens, wherein for each photosensor element, the lens passes light from at most one pixel on the original image and blocks light from all other pixels.

2. The image scanner of claim 1, the lens having some areas that are transparent and other areas that are opaque.

3. A method of scanning an image, the method comprising the following steps:

guiding, by an optical waveguide and a rotatable cylindrical rod lens having some areas that are transparent and other areas that are opaque, light from a first pixel on the image onto a photosensor element;

determining a first numerical value corresponding to the intensity of light received from the first pixel;

guiding, by the optical waveguide and the lens, without relative movement between the optical waveguide and the image, light from a second pixel on the image onto the photosensor element;

determining a second numerical value corresponding to the intensity of light received from the second pixel; and

placing the first and second numerical values into an array of numerical values representing the image.

4. The method of claim 3 wherein the light from the first pixel and the light from the second pixel are simultaneously guided onto the photosensor element.

5. The method of claim 3, further comprising:

modifying the first and second numerical values, further comprising the following step;

compensating for blurring.

6. The method of claim 3, further comprising:

modifying the first and second numerical values, further comprising the following step;

resampling to provide a resolution that is different than a resolution determined by a distance between the first and second pixels.