Data acquisition device for optical detection and storage of...

Image analysis – Image sensing

Reexamination Certificate

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Reexamination Certificate

active

06243503

ABSTRACT:

BACKGROUND OF THE INVENTION
A scanner for the electronic acquisition and storage of alphanumerical characters is already known from document WO 92/11610. With such devices, the light of a radiation source is projected via a projection device onto a predeterminable detail of a surface marked with alphanumerical characters and the reflected light is reproduced via an optical unit on an image sensor converting the light into a sequence of electronic signals. A motion detector registers at the same time the motion of the scanner along a line of characters. A signal processing electronics integrated in the reading device converts the signals into a sequence of characters each corresponding with alphanumerical symbols. The characters can be stored as alphanumerical symbols in an integrated memory or transmitted via an interface to a computer for further processing.
Such scanners are limited to acquiring and storing alphanumerical characters line by line but are not capable of acquiring graphic representations or photographic pictures.
SUMMARY OF THE INVENTION
Furthermore, a hand-held scanner in the form of a reading pen for reading in characters is known from international application WO 94/00825. For this purpose, the reading pen is moved line-by-line across lines of characters. In this process, at least part of the line is illuminated and the reflected light is captured and converted into digital information, only information representing a character or the end of a character being recorded. This information is subsequently supplied to a character recognition device and finally stored, e.g. in an ASCII text file.
This hand-held scanner has the drawback that it is possible only to read-in characters corresponding with the preset recognition pattern. Reading-in pictured information not structured alphanumerically is not possible.
A hand-held copying device that became known earlier from European patent application EP 0 278 004 does not have the above drawback. This device first picks up the entire information available in the plane of a picture and files it almost unprocessed in a matrix data memory.
However, this device, too, is designed only for time-oriented data acquisition. This has the drawback that a text arranged, for example, in a curve can be acquired only by gathering a substantially quadrangular detail covering the entire region of the curve, which means that an amount of data not of interest for the predominating part is always jointly acquired and filed.
Therefore, the invention is based on the problem of creating a data acquisition device permitting memory-optimized acquisition of any desired information available in the plane of a picture free of any direction of motion preset for such acquisition.
This problem is solved by a data acquisition device with the features of claim
1
or claim
26
.
When employed as intended, the data acquisition device as defined by the invention acquires in an optical manner a freely selectable part of an image plane marked with alphanumerical characters, graphics or photographic images, and converts the optical signals into a sequence of electronic signals, which are stored in a manner accessible to further electronic processing with retention of the complete original pictured information, and which can be recalled. An “OCR” (Optical Character Recognition) text search software thus can be dispensed with.
Illumination usefully should take place with monochrome light in order to avoid distortion of the optical acquisition due to dispersion. Infrared light is particularly suitable in this connection because it has greater depth of penetration than visible light on marked surfaces usually employed such as, for example, white paper, so that it permits distinguishing the information to be acquired from impurities.
So as to allow variable adjustment of the image plane section or segment to be acquired, it is useful if a projection device having a shutter with a variable aperture is mounted on the data acquisition device. Particularly suitable for this purpose is a slotted shutter whose slot size is infinitely variable and permits acquisition of a beam-like detail.
In the interest of a simple structure of the data acquisition device provision is made according to a useful further development of the invention that the radiation source is integrated in the image sensor, so that the light of said source is guided through the same optical channel as the reflected light.
Particularly simple handling is obtained if the motion detector is connected with the data acquisition device in a fixed manner, and if said detector has a scanning element which is designed rotation-symmetric and which is arranged on the motion detector in such a way that it is rotatable about at least one axis as well as guidable along the area to be acquired.
Detection of the movement of the data acquisition device on the section usefully can take place with the help of the Hall-effect. To this extent, provision is made according to another important further development of the invention that the motion detector has a Hall-element with a scanning element, whereby the scanning element is surrounded by an inhomogeneous magnetic field. The rotary motion of the scanning element causes a periodic change in the Hall-voltage induced in the Hall-element. Said effect permits the determination of the position of the data acquisition device on the section.
According to another further development the scanning element consists of a sphere supported in a freely rotatable way and having magnet platelets arranged on its surface, such small plates being equally spaced from each other. The movement of the data acquisition device on the section can be detected in this way both in the horizontal and vertical directions.
In another embodiment, the data acquisition device is provided with an electronic closure, through the actuation of which it is possible to freely determine that part of the section which is to be filed by the signal processing unit in an information packet.
For more rapid information processing it is possible to integrate the one or more memories intended for receiving the information packets in the signal processing unit.
In yet another embodiment the signal processing unit may have devices for connecting external memories. It is possible in this way to store also comprehensive texts or complex pictured documents.
The current uptake and the operating voltage can be clearly reduced if the signal processing unit and the memory unit are already integrated in the image sensor.
For external further processing of the data it is useful if the signal processing unit and/or the memory unit of the data acquisition device are optically, electronically or opto-electronically connected to an interface for transmitting data to external devices.
For easier handling, the data acquisition device should be equipped with a battery current supply which usefully can be operated with rechargeable batteries. The current infeed for charging the batteries takes place either via a slide-in device that is detachable from the data acquisition device, or via a cable connected to the interface. The process for charging the batteries can be optimized also by integrating a charging electronics preferably in the computer interface card subjecting the charging process to continuous electronic control.
Furthermore, advantageous is also the possibility of continuously controlling the acquired or stored data. According to a further embodiment of the invention, a monitor may serve for this purpose, such monitor being controlled by a signal processing chip integrated in the signal processing unit. Thus the acquired image information can be visually displayed online. However, it is possible also to call in all information packets which were filed in the memory unit and which are visible as readable image representation. The monitor can be designed in this connection also as a slide-in unit which, when required, can be connected to the reading device, or also can be separated from the latter.
The low space requirements

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