Reader for decoding two-dimensional optical information

IS 2 139 654 T3

DESCRIPTION

Reader for decoding two-dimensional optical information.

Background of the invention

1. Technique field

The present invention is directed to optical information readers and particularly readers adapted to selectively decode two-dimensional optical information equipment.

two. State of the art

Conventional barcode symbols have poor data storage capacity. This reduces the usefulness of conventional barcode scanning and reading systems. For example, the 11-digit Uniform Price Code found on most supermarket items acted as an identification number that can be used to access information from a database. Codes of this type carry no information across their vertical axis, and are therefore less prone to misrepresenting errors during decoding.

Two-dimensional barcode symbols or "portable data files" have recently been developed. With codes of this type it is not necessary to access a database since the code contains the information that would normally be in code in a database. Since there is no need to rely on a database, information can be accessed and exchanged more quickly and reliably. However, decoding two-dimensional codes requires a more sophisticated apparatus. This is true mainly because there is no normal vertical redundancy of the code, making registration, orientation, and code status very important.

Several two-dimensional coding standards have been proposed, e.g. eg, Code 49, 16K, Identicode MLC-2D, and Code PDF417. While such codes are capable of storing information such as price, product name, manufacturer, weight, expiration date, inventory date, shipping information, and the like; devices that help the user to direct and decode two-dimensional codes are not currently available. For example, two two-dimensional codes can consist of a group of conventional linear codes. Each line may contain different information, such as (1) pricing information, (2) product name, (3) manufacturer name, (4) product weight, (5) expiration date, (6) inventory date, (7) shipping information, and the like. In addition, the user may specify the ability to selectively store or send parts of the decoded barcode symbol.

3. Objects of the Invention

Accordingly, it is a primary object of the present invention to provide a scanner adapted to selectively read two-dimensional optical information sets.

Another object of the present invention is to provide a scanner adapted to selectively read two-dimensional optical information equipments with ambient light.

Another object of the present invention is to provide a scanner adapted to selectively read two-dimensional optical information sets from a wide range of distances.

Another object of the present invention is to provide a scanner adapted to selectively read two-dimensional optical information sets while helping the user to direct the reader.

Another object of the present invention is to provide a scanner adapted to selectively read two-dimensional optical information sets that is inexpensive to manufacture and durable in use.

Finally, another object of the present invention is to provide a scanner adapted to selectively read two-dimensional optical information equipment that is efficient in its operation, of simple construction, easy to use, and that does not have problems. These and other objects would be obvious to those skilled in the art.

EP-A-0 385 478 discloses an apparatus for scanning two-dimensional barcodes, comprising a 2-D CCD, a RAM video, a control means, an automated focusing means, a zoom mechanism, a decoder and a means of energy feeding. However, it is believed that the apparatus of EP-A-0 385 478 incorporates some of the disadvantages of the state of the art. Summary of the invention

The present invention is defined in Claims 1 and 13. The apparatus according to the invention includes a new scanner for reading two-dimensional optical information equipments. In an exemplary embodiment the invention includes a housing for holding a photosensitive device associated with an optic medium (eg, the so-called ooptic ordered sequence medium) that is adapted to focus ooptic information on the device. Device and optic sequence control means are also provided to control the device and optic sequence such that selected image outputs in the device are processed by means of optional pattern recognition means. Images recognized as containing decodable optical information are displayed and highlighted by the display medium. In this way, the user is helped to direct, recognize, and confirm the decodability of the image incident on the device. Brief description of the drawings

Other objects and advantages of the invention will become clear after reading the following detailed description and after referring to the drawings, in which:

Figure 1 is a perspective view of a preferred embodiment of the two-dimensional o-optical information reader showing a user being assisted in steering by the reader's viewer;

Figure 2 is a partial top perspective view of the reader illustrating the display in which the display indicates to the user that a decodable, two-dimensional barcode symbol can be read if the user adjusts the direction of the reader to the left and up. ;

Figure 3 is a partial top perspective view of the reader illustrating the display in which the display indicates to the user that a code symbol

Two-dimensional bar ES 2, decodable, visually centered and ready to read;

Figure 4 is a highly schematic perspective view of the image pickup elements of an exemplary embodiment of the linear device of the present invention;

Figure 5 is a highly schematic perspective view of the image pickup elements of an exemplary embodiment of the two-dimensional device of the present invention;

Figure 6 is a block diagram illustrating the various components of the present invention; ^Y

Figure 7 is a more detailed block diagram illustrating the various components of the present invention.

While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all the alternatives, modifications and equivalences that may be included within the scope of the invention.

Description of preferred exemplary embodiments

Two preferred exemplary embodiments of the present invention 10 and 100 are illustrated in Figures 1 through 7 (Figures 1, 4, 6, and 7; and Figures 1, 5, 6, and respectively). Both embodiments teach the construction and use of readers capable of decoding "portable data files."

Each exemplary embodiment utilizes an image acquisition means, a pattern recognition means, and a real-time viewer to assist the user in directing, recognizing, confirming decodability, and decoding two-dimensional bar code symbols. The embodiments (10, 100) differ primarily in the particular construction and operation of their image acquisition means.

In a first exemplary embodiment 10 the image pickup means 12 uses a one-dimensional photosensitive device 14 to read images in the horizontal direction (X) and a mechanical means 16 to read images in the vertical direction (Y). Conversely, in a second exemplary embodiment 100, the image pickup means 112 uses a two-dimensional photosensitive device 114 to read images in the horizontal (X) and vertical (Y) directions (Figure 5).

Returning to the first exemplary embodiment 10, which has an image pickup means 12, best illustrated in Figure 4, the vertical components 16 of a two-dimensional barcode symbol 20 are read by interlocking successive horizontal components 18 along of a single line photosensitive device 14. This is achieved, in such an exemplary embodiment, by means of a mirror 22 rotatably mounted on its horizontal plane. Mirror 22 is rotatably connected and driven by mirror control means 24. In a preferred exemplary embodiment, an extremely low mass mirror prism may be used and driven by solenoids, a piezo, or the like.

In this embodiment 10, a 5,000 pixel expanded single lane photosensitive device 14 can be used. However, also

654 T3 4 will serve with a smaller range a 2048 pixel one-dimensional line photosensitive device. A special photosensitive device could also be designed with faster line scan times and lower power requirements.

The vertical raster (Y) is variable under the control of microprocessor 26 (Figure 6). Likewise, the reading speed of the photosensitive device 14 is variable under the control of the microprocessor 26 in which the reading is preferably based on analyzed data obtained in each scan. Likewise, the data on the integration time and the gain of the output amplifiers and filters that act on the photosensitive device 14 can also be variable under the control of the microprocessor 26.

In addition, an electronic option can also be incorporated to read lower density bar code symbols in which it can be read every first, every third, or every fifth pixel. Likewise, an electroanic option can also be incorporated to read short ordered sequences of high density in which the paxels on the left 1666 are read, then the central 1666, and then those on the right 1666.

In another exemplary species of this embodiment 10 the pulse register transmitters of the photosensitive device are located within the device. Electronic control of each charging reservoir may also be provided such that unused reservoirs will not exist for the microprocessor 26. Such a configuration prevents dimming currents from filling the empty reservoirs. Furthermore, the reservoirs may also be created by the microprocessor 26 just prior to use. Thus, no special purification cycles will be necessary. In any case, the apparatus of the invention includes a memory means for storing the outputs of the device. Memory is optionally volatile.

In another exemplary species of this embodiment 10 the interface may be more parallel in which multiple pulse sections may each drive their own output, for example, five outputs (each driving 1000 pixels), or ten to 500 pixels, etc. Such a design would also use square pixel dimensions to maintain the same vertical and horizontal density.

Image pickup means 12 may also include automated focusing means. Autofocusing could be achieved by independent ultrasonic or infrared means, or through the use of scans from the photosensitive device to maximize the transit sharpness of the received image, or the like. Likewise, the image capture means 12 would also include user-controlled zoom.

Direction of reader 10 would be achieved by close range physical proximity (two inch contact). The use of marker light beams is undesirable because of their additional cost and their tendency to degrade in illuminated areas. Direction of reader 10 at long range would be achieved by means of a scope (<1 at 20 feet mine). The viewfinder 28, in a preferred exemplary embodiment, would be a specialty LCD, one-inch CAT graphic display, or even a terminal display.

ES 2 139 654 T3 of an integrated scanner.

In such an embodiment 10 low resolution scans can be performed while targeting. Image processing techniques would then be used to visualize lines and shadows with sufficient directional detail (Figures 1, 2 and 3). The microprocessor 26 will then use pattern recognition techniques to locate rectangular shapes (or other encoded forms of information). When microprocessor 26 locates rectangular shapes (or other encoded forms of information) that may be decodable bar code symbols, the shape closest to the center of window 30 of reader 10 will then be displayed on display 28 in a highlighted manner. eg, flashes, video investment, or similar. During this same period of time the microprocessor 26 may also attempt to decode the contents of the highlighted area. Later, if the decoding attempt is successful, the highlighted area may return to normal, or similar, to notify the user that the decoding was successful and that the user can accept or reject the data. If the data is from the wrong barcode symbol, or the wrong part of a correct barcode symbol, then the user can go to a new area without accepting the data.

Using the zoom during steering is cluttered, therefore to overcome this problem, more data can be scanned than can be seen in viewfinder 28. If 1,000 pixels are collected but only 700 are seen in viewfinder 28, then the microprocessor 26 can compare the overall patterns of each scan to detect motion and adjust the data sent to display 28 to compensate for motion. Also, when the displayed part of the obtained pixel box reaches the outline of the pixel box, then the displayed box will start to move such that the center of the obtained data will be shown as the displayed box. In another kind of an exemplary embodiment 10 all rectangular areas of the displayed area can be highlighted to indicate to the user which areas are likely barcodes, and that the barcode symbol, or part thereof, can announce that the microprocessor 26 is on. currently trying to decode.

The lighting may come from an internal source, LED or similar, where light 34 will be on continuously during addressing and decoding. Light 34 will be variable under the control of the processor to reduce power consumption. In addition, local lighting will only be necessary at a nominal distance. Apart from this, the ambient light will contribute more and more to the effective illumination of the bar code. Indoors, lighting will be required using projectors or vertical indoor lights. The intent of this design is such that if the user can see the bar code, so can the reader 10, and decoding is possible.

Both neural and fuzzy logic network processor programming as well as hardware design / architecture are accurate. Digital signal processing techniques can also be used to help improve the basic data obtained up to the normalization of the signal level in the rectangular areas of the bar code, taking advantage of the fact that bar codes are still only printed in two colors. The concepts of neural network of weighted inputs and highly parallel processing will then be used during directing and during the search for potential rectangles of the barcode 20.

The use of concise special function processors, each with a single function, all downsized to silicon and housed in a single ASIC, is preferred. In this way, the microprocessors 20, in which one searches in a vertical line, another in a horizontal line, and another at an angle, will all be able to examine the same database at the same time. Very high speed data (image) evaluation will also be used in the preferred embodiment for both directing and decoding. The same microprocessors may be responsible for controlling the energy of the image capture means 12. Furthermore, it is preferred that power is not supplied to all processing functions at all times or at the same time. Also, the illumination will end and the calculation (data) will cease after the data is decoded. A communication processor will also be provided and such communication processor will be functional until the data is transferred.

The typical operation may be as follows: The user directs the reader 10 towards the bar codes 20 to read them (Figure 1). The user pulls on an activator means 40 to activate the steering sequence. The user views the display 28 to verify the direction of the reader 10. The reader 10 is automatically focused, beginning with setting the focus of the previous reading. The user views the display 28 and moves the reader 10 and begins to zoom long enough for the symbol of the desired barcode 20 to appear in view (Figure 2). Reader 10 continues to display the field seen on display 10 even while decoding the symbol of barcode 20. Reader 10 highlights the symbol of decoded barcode 20 (Figure 3). The user can accept the decoded data by means of the trigger means 40, or the like. If the user does not want the data, they can move the reader 10 so that another symbol of the desired bar code 20 is centered and highlighted as decoded, or so that no bar code is highlighted and no decoding occurs.

This feature is very beneficial in that you can select a barcode on a page that contains many adjacent codes without the sometimes impossible requirement to ensure that the scan line (laser) goes only through the desired code.

Figure 7 is a block diagram illustrating the organization into functional blocks of an exemplary embodiment of the present invention. The optic ordered sequence 200 enables image focus and zoom. Management of both focus and zoom is provided by control processor 202. Input switches 204, such as trigger 40, can be used to enable the scan function, or

ES 2 139 654 T3 similar. In scan mode, focus can be achieved according to at least two methods. As shown, there is a focus block function 206 that can utilize a different range detection circuit (ie, such as an ultrasoonic or infrared range medium). This is the first type of focusing method. This method allows the control processor 202 to determine the range of an image from the scanner and to move the target 208 accordingly without using all the power, or at least without operating the circuitry of the image sensor 210, the data analysis means 212 , and the viewer 214. In this way the battery power is conserved. The second type of focusing method uses image sensor 210 / processing means 212 to detect an out of focus by data rate analysis, i.e. moving target 208 to maximize the high-frequency content of the image data. . The second type of focus requires fewer parts, but more energy and the initial corrective movement can be made in the wrong direction. Using the history of past addresses will improve the chances of a correct starting address choice. Also all focus adjustments ooptically required due to zoom changes can be obtained from the look-up table of the control means and included in the focus control during zoom changes.

The image sensor can be a single line sensor of several thousand pixels (at least 1000 to 5000 pixels depending on the demands of the scan) or a device sensor with from at least 500 to 1500 pixels in both X-axes. and Y. The preferred way is to use a sensor from the device as it is faster and requires fewer moving parts. However, the cost and energy demands are greater with a device sensor.

As previously discussed, a one-dimensional device requires movement in a direction orthogonal to the pixel arrangement to obtain a 2-D image. The pixels of both sensors are square in dimension to maintain relative dimensions in both the X and Y directions. One method of providing vertical oscillation (back and forth) is by means of a mirror driven by piezoelements in a folded optic path. However, a rotating polygonal cylinder can also be used.

To reduce energy and gain speed when rectifying an image, both image sensor methods allow partial reading of sensor fields. This means that during linear scanning of a single line sensor, a programmatically controlled number of pixels are collicly bypassed in the sensor to obtain less dense scanning information more quickly. For example, reading only every other, every third, or every fifth pixel means fewer pixels are taken to process the data. A less detailed image is acquired, but speed, great detail is not required for general direction and configuration. In the vertical direction, the mirror moves even more between samples to compensate for the partial sample of pixels and to keep spatial relationships constant. With a two-dimensional device, the same partial pixel vision is made in both directions at the same rate. Both types of sensor allow a controlled exposure time independent of cycle time.

The control processing means contains at least one microprocessor. The control processor is responsible for controlling focus, zoom, lighting (if necessary), sensor timing, power management, and communication with other blocks in the system. The control processor uses fuzzy logic decision structures to focus quickly and to analyze the image model as a whole. It is also responsible for controlling the sensor when ordered sequences of high density pixels are removed from parts of the sensor. This is useful when a low density pixel scan has enabled the processing function to recognize a potentially decodable shape.Then a maximum density scan is done on that part of the sensor to try to determine if decoding is possible. These high-density scanning parts can consist of the left, center, and right sensor sections. This can also be achieved by programming start and stop points on the sensor to control which section is removed.

Under zoom conditions, the movement of the user will be more obvious and objectionable. The processing control means controls the image sent to the viewer to assist the user in directing the scanner unit. The processing function means helps to eliminate disturbances caused by the movement of the user by modifying the image sent to the viewer. The image sent to the viewfinder is a small part of the actual scanned image. Again fuzzy logic structures are used to determine patterns and shapes and track their movement. The smallest image (or subset) that is displayed remains, placed as it is, in the viewfinder until the image in the viewfinder hits the edge of the true image obtained. Then the image in the viewer begins to move in time with the user's movement. The processing medium is continuously working to reduce disturbances while also trying to recognize and decode potentially decodable images. It also enunciates potentially decodable images in the viewer, for example by surrounding an image with a continuous outline, and marks fully decoded images in another way, such as a video reversal.

The communication control means 220 communicates with the processing and control means to provide an interface to a host system. Communication control means 220 may also have its own microprocessor to handle protocols and data transfer. In a restricted version 216 the battery power can be autonomous or derived from a portable terminal with manual operation. When using a wireless link 218 the communication control means can also control the RF or IR link.

The present invention can be built to

ES 2 139 654 T3 used in a docking type system to recharge / communicate with the apparatus disclosed herein. A coupling unit that could be adapted for use with the present invention is set forth in pending US patent application No. 5,227,614 which illustrates arrangements that could be made in a peripheral shell 260 (Fig. 10; 07 / 451,322). Likewise, the exposition of United States Patent No.^°4,877,949, issued October 31, 1989, illustrates a means of focusing an image of optically legible information over a substantial range of distances. US Patent No.^° 5,227,614 illustrates a display 14 (Figs. 13 and 14) adapted to assist the user of an apparatus to read optically readable information. Finally, US Patent No.^°5,227,614 illustrates a means of digitizing and decoding optical readable information (Figs. 7ala18). Although the invention has been described with a certain degree of particularity, it is apparent that many changes can be made in the details of construction and arrangement of the components without leaving the scope of the discussion. It is understood that the invention is not limited to the embodiments proposed herein for purposes of exemplification.

Thus, an improved two-dimensional ioptic information reader has been shown and described.