Optical image reader

Optical image reading equipment is disclosed, whereby a background color of a document can be changed depending on a processing of the acquired image. The equipment is provided with an illuminating member (32) for illuminating a document, a reading portion (30) for reading reflected light of the document, and a backing member provided at least in the reading position of the document. The backing member is disposed on the opposite side to the reading portion across the document. The backing member is configured by a member which produces background color outside the document changeable by means of electric control. Thus an image suitable for a successive processing can be output.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an optical image reader and more particularly to an optical image reader whereby a background color outside a document sheet can be changed.

2. Description of the Related Art

Optical image reading equipment is used as computer peripheral equipment to read by optical means two-dimensional image of a document. An image thus obtained is input to a computer for further processing. In recent years, various kinds of computer image processing have been developed. It is desired to obtain an image suitable for individual image processing.

InFIGS. 12 and 13, a conventional method is illustrated. As shown inFIG. 12, optical image reading equipment produces an image of a document91by detecting light reflected by document91. A reading portion90having a light detection element (e.g. CCD) is provided to detect reflected light.

In reading portion90, the reflected lights in an entire reading area, which is irrespective of the document size, are converted to electric signals to output an image data. The obtained image data, therefore, contains an image of document91as well as a background part92positioned outside document91.

Now, when the image is processed in a recognition processing such as OCR (optical character recognition), a significant image such as image of characters in document91can easily be extracted if the color of background part92is the same as the texture color of document91. For example, when reading document91having white texture as shown inFIG. 12, black color characters in document91can easily be recognized if background part92is white.

On the other hand, in case of image filing processing etc., images in entire part of document91must be extracted. Also as shown inFIG. 13, when document91is obliquely placed on a platen, the oblique movement must be corrected electronically. In such cases as extracting whole images of document91, it is preferable that the color of background part92is different from the texture color inside document91. As shown inFIGS. 12 and 13, image of document91having white texture can easily be extracted if background part92outside document91is black.

The above-mentioned color of background part is determined by a color of a backing member provided in the reading position. Such backing member is fixed in position in case of either a sheet-feed type image scanner, where an image is read while a sheet is transported in the sub-scanning direction, or image reading equipment having optical system provided in a fixed position for reading a sheet on a platen.

For the above reason, in order to obtain proper images, it is required to use different image reading equipment depending on the situation: image reading equipment having a white backing member to obtain images for a recognition processing such as OCR, or image reading equipment having a black backing member for an image processing.

In the conventional method, it is difficult to configure image reading equipment having different backing member into one equipment. Accordingly, it is difficult to use the same equipment both for recognition processing and for image filing processing. In short, two different sets of image reading equipment are required to perform both processing described above.

In addition, recently various software systems have been developed. A single personal computer which has been introduced to conduct a processing by a software can be used for another processing simply by installing another software. A problem arises if image reading equipment which has been purchased for a processing can not be used for another processing, requiring another image reading equipment to be newly purchased.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide optical image reader which enables to change color of the background part corresponding to the purpose of the image acquisition.

It is another object of the present invention to provide optical image reader which produces variable background color with a simple structure.

It is still another object of the present invention to provide single optical image reader for outputting images suitable for the types of processing.

To achieve above objects, an optical image reader according to the present invention comprises: an illuminating member for illuminating a document, a reading portion for reading reflected light of the document, a backing member provided at least in the reading position of said document and disposed on the opposite side to said reading portion across the document and for changing the background color outside the document by electric control.

According to the present invention, the backing member consists of a member of which background color can be changed by electric control means. This enables to output an image suitable for each image processing by changing background color electrically even in case the backing member is secured to the equipment. In addition, electric control provides easiness to change background color whenever it is necessary.

Another aspect of the optical image reader of the invention is that the backing member consists of electro-optic material having variable reflectivity, which easily enables to change background color.

In further aspect of present invention, the backing member is configured by liquid crystal member having variable light transmittance and reflective body. Using liquid crystal member available at low cost enables to realize low cost equipment as well as prevent the equipment from becoming large in size.

As yet another aspect of the optical image reader according to the present invention, a controller is provided for controlling by electric means reflectivity of the electro-optic member which enables easy change of background color.

Furthermore, the controller in the image reader of the present invention controls reflectivity of the electro-optic member by electric control means corresponding to a program read in to process the image. Accordingly, a desired image for executing image processing program can be output automatically.

The image reader in accordance with the present invention is provided with a sheet feeder for transporting the document. This type of equipment requires a small backing member which enables to maintain low equipment cost.

Further scopes and features of the present invention will become more apparent by the following description of the embodiments with the accompanied drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the description of the preferred embodiments of the present invention, the embodiments of image reader, reading mechanism and controller are independently explained hereinafter, together with other embodiments.

Image reading equipment of an embodiment according to the present invention is shown, taking an example of sheet-feed type image scanner.FIG. 1is a front view of the image reading equipment.FIG. 2is a side view of the image reading equipment.FIG. 3is a cross-sectional view of a reading mechanism.

As shown inFIGS. 1 and 2, an image scanner1includes an entrance10for placing a document and the like, an inlet11for inserting the document, an outlet13for ejecting the document having been read, and a receiving portion12for receiving the ejected document. An operation panel14is provided in the front surface of image scanner1.

As shown inFIG. 3, the reading mechanism includes; a sheet-feed mechanism23to transport a document inserted from inlet11continuously to outlet13; an optical unit20to read an image on the front surface of the document being transported; another optical unit21to read an image of the back surface of the document being transported. On the opposite side of respective optical unit20and21, backing members (liquid crystal members)24and25are provided respectively.

Optical units20and21are constituted by the known art including a mirror for producing an optical path length, a lens for focusing, and a photoelectric converter for converting reflected light to electric signal. The photoelectric converter consists of, for example, a CCD (charge coupled device). Backing members24and25consist of electro-optic elements as described later.

The operation of the reading mechanism is explained below: a document inserted from inlet11is transported continuously to outlet13by means of sheet-feed mechanism23. Meanwhile, the optical unit20reads an image on the front surface of the document being transported and the optical unit21reads an image on the back surface of the document.

Above example shows a case of double-sided reading mechanism. Needless to say, a single-sided reading may also be possible.

InFIGS. 4 and 5, configuration diagram of a reading mechanism are shown. InFIGS. 6 and 7diagrams illustrating liquid crystal film are shown, and inFIG. 8an operation diagram is shown.

As shown inFIG. 4, backing member24consists of a liquid crystal film27and a mirror (light reflecting member)28. A lamp (illuminating member)32obliquely illuminates light to liquid crystal film27. Lens31and CCD30of the optical unit20and21are provided respectively positioned opposite to liquid crystal film27.

Liquid crystal film27has a variable transmittance depending on voltage applied thereto. As shown inFIG. 6for example, liquid crystal film27includes a transparent polymer film42with scattered small particles (called capsules)41of nematic liquid crystal. Polymer film42is inserted between two sheets of polyester film each having a transparent conductive film40.

The operation of liquid film27is illustrated below: When voltage is not applied to transparent conductive film40, as shown inFIG. 6, liquid crystal molecules in capsule41are irregularly arrayed, causing incident light to be scattered. On the other hand, when voltage is applied to transparent conductive film40, as shown inFIG. 7, liquid crystal molecules in capsule41are regularly arrayed, causing the incident light to be transmitted, not scattered.

Using the above characteristic of liquid crystal film27, background color outside the document can be changed in the following manner: As shown inFIG. 4, liquid crystal film27and mirror28are positioned facing to an optical reading system (CCD30and lens31). Light from a lamp32is irradiated obliquely. Here, liquid crystal film27and mirror28are provided at the backside of the document, viewed from the optical reading system, in the document reading position of the reading system.

As shown inFIG. 4, when voltage is not applied to liquid crystal film27, irradiated light from lamp32is scattered at liquid crystal film27because liquid crystal film27scatters light in this situation. A part of light proceeds toward optical unit21(30,31). Also, light once transmitted through liquid crystal film27reenters into liquid crystal film27by means of mirror28, which is then scattered and a part of light proceeds toward optical unit21.

Therefore, more than half of the irradiated light from lamp32reaches CCD30of optical unit21, making background color white. Of course, actually document91is placed on liquid crystal film27. However, inFIG. 4there is shown an operation at the background where the document is not placed. In addition, document91is transported in horizontal direction in FIG.4.

On the other hand, as shown inFIG. 5, when voltage is applied to liquid crystal film27, irradiated light from lamp32is transmitted through liquid crystal film27because light is transmitted through liquid crystal film27, as explained before. The light is then reflected by mirror28and reenters into liquid crystal film27.

Most of the irradiated light from lamp32does not reach CCD30of optical unit21, making background color black. Also in this case, actually document91is placed on liquid crystal film27. InFIG. 5, therefore, an operation at the background where the document is not placed is shown.

InFIG. 8A,8B and8C, operation diagrams according to the present invention are shown. InFIG. 8A, there is shown an output waveform of CCD30when document91shown in the figure passes through. Here, document91is placed on a conventional backing member92of which color is fixed (white). The output level of the background at both outer sides of document91is equal with the level of the texture inside document91. The level corresponding to this background is not changeable.

On the other hand, as shown inFIG. 8C, when document91is passed through on backing member24while the voltage is not applied to liquid crystal film27, irradiated light from lamp32is scattered at liquid crystal film27because liquid crystal film27scatters light as explained before, and a part of light proceeds toward optical unit21(30,31). Also, light once transmitted through liquid crystal film27reenters into liquid crystal film27and is scattered. This causes a part of light to proceed toward optical unit21. As shown in the figure of an output waveform of CCD30, the level corresponding to the background outside document91reaches approximately 60% of the level of the texture inside document91.

In the case shown inFIG. 8B, when document91is passed through on backing member24while the voltage is applied to liquid crystal film27, irradiated light from lamp32is transmitted through liquid crystal film27because, in this case, liquid crystal film27transmits light as explained before. This results in the light not proceeding toward optical unit21(30,31). As shown in the figure of an output waveform of CCD30, the level corresponding to the background of both outer sides of document91is approximately 10% of the level of the texture inside document91.

As a result, when a level for slicing is set between the two levels shown inFIGS. 8B and 8Cto obtain binary output of CCD30, a background color of either black in case ofFIG. 8Bor white in case ofFIG. 8Ccan be obtained. Approximately 50% of the output level may preferably be assigned as the level for slicing, provided that the level of the texture in document91is 100%.

In the above description, mirror28is not essentially required because the present invention utilizes scattering or transmitting of light by means of liquid crystal film27. The provision of mirror28, however, facilitates the light transmitted through liquid crystal film27to direct toward the optical unit when voltage is not applied, as shown in FIG.4and FIG.8C. Thus higher output level can be obtained for white background, producing greater level difference against the case of black background.

Also, mirror28enables to prevent incident light from entering from the back (which is opposite to the document loading plane) of liquid crystal film27. In particular, the interference between the light irradiated to the surface and the back can be prevented in case of the double side reading mechanism shown in FIG.3.

[Controller for Image Reader]

InFIG. 9, there is shown a block diagram of the image reading equipment shown in FIG.3. InFIG. 10, a configuration of an operation panel14is shown. InFIG. 9, like numerals or symbols refer to like parts inFIGS. 3 and 4. The image reading equipment is provided with three controllers: a mechanism controller50, a scanner controller57and an image system controller58. Each controller includes an MPU.

Mechanism controller50controls a mechanical portion based on a program stored in EPROM51. Scanner controller57controls an entire scanner. Also, image system controller58controls an output of image signals. A liquid crystal controller52controls whether to apply voltages to liquid crystal film24,25(27) or not to apply, in accordance with a command from the mechanism controller50.

A motor driver53drives a conveying motor of a sheet feeder23. A sensor controller54inputs and outputs signals of each sensor provided in sheet feeder23. A lamp controller54controls a lamp (fluorescent lamp)32according to a command from mechanism controller50.

Video circuits59and60respectively generate binary values from outputs of CCD30to convert into video signals. An image processing portion61processes images from video signals. A memory62temporarily stores video signals etc. An interface63transfers signals from/to a host. A DPRAM56acts as an intermediate memory for signal transfer between controllers50and57.

As shown inFIG. 10, operation panel14is provided with a display portion14-1, a menu key14-2, moving keys14-3, a determination key14-4and a cancel key14-5. A menu (such as selection of white or black as the background) can be specified by menu key14-2. Cursors etc. can be moved by moving keys14-3. Determination key14-4is used for the determination of selection. In this example, a background color can be specified using operation panel14.

InFIG. 11, there is shown an operation diagram for changing background color.

When a background color is specified using operation panel14, scanner controller57receives this request, then indicates mechanism controller50to control liquid crystal via DPRAM56. Mechanism controller50controls to apply voltage to liquid crystal films24and25through liquid crystal controller52according to the received indication related to background color. In the example shown above, liquid crystal controller52does not apply voltage to liquid crystal films24and25when white is specified as the background color. On the other hand, liquid crystal controller52applies voltage to liquid crystal films24and25when black is specified as the background color.

Also, by means of a command issued from a host via interface63, scanner controller57and mechanism controller50control liquid crystal controller52for controlling to apply voltage according to the indication of background color. The host generates a command for specifying suitable background color depending on whether a current processing triggered by a program is OCR recognition processing or image processing. Thus depending on the processing triggered, background color can automatically be changed, and images having suitable background color for the processing can be transmitted to the host.

In addition to the aforementioned embodiment, the following modifications are possible.

(1) As a backing member which is electrically controllable, other electro-optic element than liquid crystal film may also be used, such as a liquid crystal panel etc.

(2) Although the above description is based on the sheet-feed type scanner, the invention is also applicable to a fixed-sheet type scanner.

Any other suitable modification may be possible, which are resorted to the scope of the invention. The foregoing description on the embodiments is not intended to limit the invention to the particular details of the examples illustrated.

The following effects can be attained by the present invention.

First, the backing member is configured by a member which electrically enables background color to be changeable, so that an image suitable for the successive processing can be output.

Secondly, as background color is changed electrically, background color can be changed even in case of image reading equipment having a fixed backing member.

Thirdly, background color can easily be changed by electric control means according to a successive processing of an obtained image.

All features and advantages of the invention which fall within the scope of the invention are covered by the appended claims.