Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-03-05
2002-04-02
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S474000, C358S506000
Reexamination Certificate
active
06366367
ABSTRACT:
The invention relates to a method and to a device for the digital detection of both transparent and opaque documents, with a CCD pick-up element, a document holder, an illuminating device, as well as elements (masking unit) for covering the edges of the documents.
A device of the type specified above is known from DE-OS 42 17 210.
Said device is employed for the digital detection of X-ray pictures and has an image pick-up element designed as a CCD-line. Said pick-up element is employed in the form of commercially available hand-held scanner picking up reflected light, or as a flat-bed scanner—which is commercially available as well—with a stepping motor for moving the image pick-up element.
A hand-held 256-grey tone scanner with a resolution of 400 dpi is preferably employed.
However, the pick-up process takes a very long time because the lines are picked up one by one, so that the achievable throughput rate is low, on the one hand. On the other hand, precautionary measures requiring much expenditure have to be implemented for keeping the illumination required for the pick-up proce-s constant.
Furthermore, only a few present document sizes can be processed by means of the known device. For other document sizes, provision is made for placing opaque screening strips on the document for covering the edges of the latter. This has an additional negative effect on the handling of the known device and further increases the expenditure in terms of time.
In view of the fact that predominantly analog X-ray pictures will be produced in the field of radiology over the next 10 to 15 years, which have to be digitized so that they can be optimally filed, processed further and used without problems, for example in the field of tolemedicine, excessive demands are made upon the known device for handling said tasks in a satisfactory manner. Furthermore, distinct losses ensue in this connection of the image quality versus analog images.
Therefore, the invention is based on the problem of designing a method and a device of the type specified above in such a way that both can be controlled in a simple and quick manner, on the one hand, and that documents of any type and size can be reproduced without any loss of quality, on the other.
The invention solves said problem with respect to the method according to the characterizing part of claim
1
by the following process steps:
(a) Placement of the document on the document holder.
(b) Determination of the size of the document.
(c) Automatic adjustment of the zoom lens to the document.
(d) Automatic adaptation of the masking unit to the size of the document.
(e) Start-up of the exposure process.
(f) Automatic adjustment of the illumination by determining the dynamic range of the image intensity.
(g) Exposure of the CCD-chip in the camera (one shot).
(h) Reading of the digitized data into the memory of the PC.
(i) Further processing of the stored data in the PC or on external data processing equipment.
Furthermore, the invention solves said problem according to the characterizing part of claim
2
in that the pick-up element is a CCD-camera, which is equipped with a motor-driven zoom lens with automatic focusing; that the masking unit is arranged below the document holder between the latter and the camera, said masking unit consisting of four opaque roller blinds with motor-driven adjustment, each two of which opposing one another are arranged in such a way that they can be synchronously adjusted relative to each other; and that the drive of the zoom lens and the drive of the masking unit are controllable in coordination with each other via a software.
In the aforementioned DE-OS 42 17 201, reference is already made to the use of the CCD-cameras with a flat CCD-sensor, in connection with which the image to be detected is read into the CCD-chip in the course of one single exposure process.
However, such a camera is said to have various drawbacks such as, for example the occurrence of edge distortions, which are said to lead falsification of the reproduced image, as well as the alleged necessity of extensive adjustment work.
Said prejudices are overcome by the design of the device as defined by the invention.
The device as defined by the invention is not suitable only for digitalizing analog X-ray pictures of technical or medical origin or other transparent documents to be processed by the transillumination method, but also for detecting other documents by reflected light.
The document is picked up the CCD-camera equipped with the self-focusing zoom lens in one single exposure process, whereby the control of the camera, the selection of the cutout and sharp focusing take place fully automatically, or via a user panel associated with the device.
In particular the enlargement of the motorized zoom lens located in front of the CCD-converter is controlled by the size of the image to be digitized, because the sensitive surface area of the CCD-converter can be optimally exploited in this way.
Said adaptation is realized by an allocation table stored in the form of data in a PC, said table containing the function of the size of the image and of the position of the zoom lens. In this connection, the geometric dimensions of the image to be digitized can be either preset manually (via a user panel), preferably graduated, or automatically recognized, for example by means of known methods of image processing.
Subsequently, the process of the zoom lens takes place successively according to the table described above, by means of a preferably voltage-controlled interface in the PC.
The adjustment of the masking unit is connected with the coordination of the position of the zoom lens and the detection of the size of the image. Said masking unit serves the purpose of shielding the light which, with documents which are smaller than the dimensions of the document holder, would otherwise radiate past the document, so that no undesirable light can incide in the optics of the camera.
According to the invention, the adjustment of the masking unit may take place semi- or fully automatically.
With semiautomatic masking, the roller shades of the masking unit are selected for the required adjustment to document sizes—which were previously defined in a fixed manner—by means of keys via the user panel. The control takes place either directly from the panel or via the PC.
With fully automatic masking, the camera recognizes the document size by means of an installed still-video function, in connection with several images are picked up per second with reduced resolution, and controls the masking roller shades upon such recognition to the respective size of the document to be picked up.
The masking unit consists of four roller shades, which are arranged and coupled in pairs opposing each other, so that roller shades opposing one another move symmetric to the center of the image. In this way, the document is always exactly placed over the optics of the camera. So that centric placement of the document with respect to the optical axis of the pick-up optics is secured, a positioning aid (e.g. in the form of a preferably optically projected diagonal cross on the document holder) is applied with the illumination cover open.
Furthermore, it is possible by means of the still-video function to determine documents cutouts that can be selected in any desired way. After such selection has been completed, said document cutouts are positioned in such a way that the cutout is exactly disposed above the camera optics.
The device as defined by the invention is advantageously equipped with both a transillumination and a reflected illumination unit. The transillumination unit forms a light cover and radiates through the image to be digitized (for example X-ray film) from behind. The light source as such consists of, for example at least four powerful flash tubes, their individual power being variable and adjustable from about 120 watts to about 240 watts. The arrangement of said four tubes assures absolutely uniform transillumination of the documents, so that no scatter will occur in the conduction of th
Brück André
Grigat Markus
Masselink Robert
Plück Frank
Schreier Hans-Hermann
Collard & Roe P.C.
DRS Digitale Repro-Systeme GmbH
Grant II Jerome
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