SU1164749A1 - Device for reading symbols - Google Patents

Abstract

1. A DEVICE FOR READING SYMBOLS containing optically coupled illuminator, a flat scanning beam formation unit and a photoreceiver, the output of the latter is connected to the inputs of the harmonic analyzer, the outputs of which are connected to the inputs of the recognition unit, and a synchronization unit, one of the outputs of which is connected to the control recognition inputs, characterized in that, in order to improve recognition accuracy by ensuring the recognition result is independent of affine image transformations, the symbol c, it contains a unit for rotating the scanning beam plane and a functional signal generator, and the flat scanning beam forming unit contains a magneto-optical crystal associated with the generator of functional signals and fixed inside the rotating ring, and an electric drive mechanically connected to the rotating ring and connected to the output block of the rotation of the scanning plane & the beam, the control input of which is connected (L with another output of the synchronization unit, and the outputs are connected to the corresponding inputs of the recognition unit.

Description

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2. The apparatus of claim 1, wherein the harmonic analyzer comprises a filter unit, the input of which is the input of the harmonic analyzer, a normalization unit and a selection unit for the maximum amplitude of the harmonics, the inputs of which are connected to

One of the outputs of the filter bank, the other outputs of which and the output of the maximum amplitude amplitude harmonic unit are connected to the corresponding inputs of the normalization unit, the output of which is the output of the harmonic analyzer.

one

The invention relates to automation and computer technology and can be used in the automatic reading and recognition of symbol images.

Symbol reading devices are known, comprising a radiation source and a photodetector, between which a storage medium is placed, a recognition unit connected to a photodetector, a coding unit and a control unit 1.

However, the known device has insufficient reliability of character recognition.

The closest in technical essence to the present invention is a symbol reading device comprising an optically coupled radiation source, a flat scanning beam formation unit and a photoreceiver, the output of which is connected to the inputs of the harmonic analyzer filter unit, the outputs of which are connected to the recognition unit inputs, and the synchronization unit , one of the outputs of which is connected to the control inputs of the recognition unit 2.

The disadvantages of this device are the limitation of the class of recognizable characters, the need for unambiguous orientation of the characters on the frame-carrier, i.e. This device does not ensure that the recognition result is independent of the rotation of the image of characters within a certain angle, and also does not provide reliable recognition of such characters whose electrical analogs are specularly reflected, for example b and d, or in cases where the symbols have the same electrical analogs, for example, H, P, b, P, etc.

The purpose of the invention is to increase the recognition accuracy by ensuring the recognition result is independent from affine transformations of symbol images.

This goal is achieved by the fact that, in a symbol reading device containing optically coupled illuminator, flat scanning beam forming unit and photo receiver, the output of the latter is connected to the inputs of the harmonic analyzer.

the outputs of which are connected to the inputs of the recognition unit and the synchronization unit, one of the outputs of which is connected to the control inputs of the recognition unit,

5, a block of rotation of the scanning beam plane and a functional signal generator are introduced, and the flat scanning beam formation unit contains a magneto-optical crystal associated with the generator

0 functional signals and fixed inside the rotary ring, and an electric drive, mechanically connected to the rotary ring and connected to the output of the rotating unit of the scanning beam plane, the control input of which is connected to another

5 by the output of the synchronization unit, and the outputs are connected to the corresponding inputs of the recognition unit.

Moreover, the harmonic analyzer contains 0 filter block whose input is the harmonic analyzer input, normalization block and maximum amplitude amplitude selection block, whose inputs are connected to one of the outputs of the filter block, the other outputs of which and the output of the harmonic maximum amplitude selection block are connected to the corresponding block inputs normalization, the output of which is the output of the harmonic analyzer.

Q In FIG. 1 is a block diagram of the device; in fig. 2 - diagram of the operation of the device; figure 3 - electric analog characters; in fig. 4 is a functional diagram of a flat scanning beam forming unit.

The device for reading and recognizing symbols (Fig. 1) contains the illuminator U. A flat scanning beamforming unit 2, an information carrier 3, a photodetector 4, a harmonic analyzer 5, which includes a filter block 6, a maximum harmonic amplification block 7, and a normalization block 8 ; a recognition unit 9, a synchronization unit 10, a unit 11 for rotating the scanning beam plane and a generator 12 of functional signals controlling the movement of the scanning beam 13 according to a certain law.

The recognition unit 9 includes keys 14, 15, and 16, nodes 17, 18, and 19 of the harmonic values memory for three fixed rotation angles and decision node 20, and in block 11 of rotation of the scanning beam plane includes a counter 21 clock pulses the counter 22 and the node 23 of controlling the rotation of the plane of the scanning beam when the orientation of the magneto-optical crystal changes in block 9.

The flat scanning beam forming unit 2 contains an active element 24 made of a magneto-optically active crystal with plane-parallel working surfaces, and biasing coils 25 with a core of magnet of a soft material and a winding wound on it opposite to the surfaces of the active element, connected to the output of block 12 generating signals that control the movement of the scanning beam according to a certain law. The active element 24 is mounted inside a rotating ring 26, which is rotated by means of an electric actuator 27, controlled by signals from the rotation of the plane of the scanning beam from block 11.

The device works as follows.

The optically coupled illuminator 1 and the node 2 form a flat scanning light beam, which, passing through the transparent information carrier 3, is modulated by the shaded part of the frame and fed to the photodetector 4, the output of which forms a periodic sequence of electrical images. This periodic sequence enters the analyzer 5 at the input of a block of 6 filters tuned to frequencies that are multiples of the oscillation frequency of the scanning beam, the outputs of which are connected to block 7, which, by alternate comparison of the harmonic amplitude values, determines the maximum value that is output from block 7 input of the normalization unit 8, which also receives signals from the outputs of the filter unit 6. Block 8 normalization contains a scheme for dividing the values of each harmonic by the value obtained at the output of block 7 (not shown).

From the output of the normalization unit 8, the relative amplitudes of the harmonics of the discrete spectrum go to the recognition unit 9. The algorithm of the recognition unit 9 is based on a comparison of reference voltages corresponding to symbols or groups of symbols with the voltage of the corresponding normalized amplitudes of the discrete spectrum HARMONIC, and the normalized harmonics values are pre-recorded in it at three fixed the angles of rotation of the magneto-optical scanning element.

The recording of relative spectra at the memory of each fixed angle of rotation 5 of the plane of the scanning beam is made in three cycles in view of the fact that the number of informative harmonics is equal to three. The operation rhythm is set by a clock generator (not shown) of the synchronization unit 10.

The timing diagram of the operation of the recognition unit 9 is shown in FIG. 2. At the initial orientation angle of the scanning plane ((the initial state of the proposed device), the recording of the three harmonics values in the node 17 is carried out through 5 key 14 in three cycles, Fig. 2a. Then, in block 11, a rotation pulse is generated that is equal in duration to the period clock pulses, which is removed from the output of the counter 21 and fed to the input of the scanning beam rotation control unit 23 and the key 14 to 0, disconnecting the output of the block 5 from the node 17, and the memory node 18, switching it to the recording mode. control voltage applied on the rotation mechanism of the magneto-optical crystal to the node 2. 5 As a result, the scanning beam plane orients at an angle с (and the harmonics value is recorded in the node 18 during the three clock pulses (Fig. 26, c). After the end of the recording in the node 18, the second rotation pulse (Fig. 2d), 0 which translates the plane of the scanning beam to the position corresponding to the angle (; 19 to record mode

5 and simultaneously to one of the inputs of the decision node 20 to turn on the reading mode of the harmonics values recorded at the nodes 17, 18 and 19. Thus, the reading of the harmonics values and their input to the node 0 20 takes place during three clock pulses (Fig 2d). After reading the harmonics in block 11, a pulse is generated to return the magneto-optical crystal to the initial state (plot 2e). This pulse is removed from the output of the counter 22 and is fed to the node 23 and the second control input of the node 20, transferring it to the comparison mode of the measured set of harmonics of the recognizable symbol with the reference values and making a decision. The duration of the return pulse is equal to 9 periods of repetition of clock pulses (graph 2e). The leading edge of this pulse puts the decision-making unit 20 into operation, the falling-edge brings the circuits of block 9 to the initial state. During the period of the return pulse, the measured set of harmonics in the three fixed angles of rotation of the scanning beam is compared with the reference sets and the subsequent classification — the decision on whether the recognized symbol belongs to one of the classes.

In this process, the reading and recognition of one character is terminated. The generator 12 of the functional signals generates signals that control the movement of the scanning beam according to a certain law, which are fed to the flat scanning beam forming unit 2. The control signals of the generator 12 are a periodic sequence of pulses of various shapes (e.g. the pulses and the generator 12 are essentially separate from the spectral recognition method, since it determines only the law of motion of the scanning flat beam a frame-storage medium and determines the form of electric analog periodised readable characters input at the input of the analyzer 5 harmonics. As an active element, a magneto-optical crystal is used with plane-parallel working surfaces located on opposite surfaces of the active element, biasing coils with a core of magnet of a soft material and a winding wound on it. The coils from the generator 12 are provided with scanning signals opposite to one another in relation to the other, for example, a voltage of an exponential form. By varying the current in the magnetization coils, according to a certain law, a narrow scanning zone moves along the magneto-optical crystal, which enables scanning of the image on the frame-information carrier, and the plane of the scanning beam is rotated due to the rotation of the magneto-optical crystal itself.

The speed of movement of the scanning zone over the active element in different sections is different, which is achieved by using control signals of a certain shape. When using control signals of an exponential form, the sweep of the image of a symbol is obtained asymmetric and non-linear, which allows to distinguish characters or figures that are mirror images of each other, such as b and d, 6 and 9, P and b, and others. .

FIG. Figure 3 shows the electrical analogs of symbols with the linear and non-linear laws of motion of the scanning beam.

The linear scanning law — the scanning beam at the same time moves at the same speed on all parts of the frame and can be obtained in the case when in the Ka4ect5 control pulses are used, for example, trapezoidal or sawtooth.

When used as control pulses of exponential form, the speed of movement of the scanning beam in different parts of the frame will be different, and therefore the electrical analogs of the mirrored or axisymmetric symbols will be different in shape.

FIG. Figure 3 shows three symbols, the electrical analogs of which are either identical in shape for the symbols P and B or are mirror images of each other b and d, and therefore have the same spectrum; trailing hara (linear scanning scan characteristics (Fig. 3.1).

With nonlinear scanning, the electrical analogs of the symbols b and d become different (Fig. 3.2).

Electrical analogs of the symbols P and L will be different when the orientation of the scanning beam plane changes (Fig. 3.3) and in non-linear scanning (Fig. 3.4).

Thus, the combination of the rotation operation and the non-linear sweep stroke allows us to distinguish between mirror-reflection and axis-symmetric symbols.

The proposed device for reading and recognizing symbols when using as information characters only three harmonics of a discrete spectrum and two different levels of harmonics

5 theoretically makes it possible to increase the size of a class of recognizable characters to a value of the order of 2, which may already correspond to a plurality of approximately 15 types of fonts for the printing industry.

With an increase in the number of gradations of informative features to four, which can be easily accomplished with simple measuring tools, the volume of recognizable characters increases to a value of 2. In this case, the device allows reading and recognizing printable characters of several tens of alphabets of different languages and font types.

The proposed device is effective when used to enter information into a digital computer. In this case, all text information can be reflected by several tens of characters, and this allows reading and recognizing characters of different types and handwritten characters independently to affine transformations.

character images. The ability to read and recognize a large amount of characters using the minimum number of informative features

allows, on the basis of this device, to create an automatic system for reading and recognizing such a class of symbols,

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Claims (2)

1. A DEVICE FOR READING SYMBOLS, comprising optically coupled illuminator, a flat scanning beam forming unit and a photodetector, the output of the latter is connected to the inputs of the harmonic analyzer, the outputs of which are connected to the inputs of the recognition unit, and a synchronization unit, one of the outputs of which is connected to the control inputs of the recognition unit, characterized in that, in order to increase the reliability of recognition by ensuring the independence of the recognition result from affine transformations of symbol images, but it contains a block of rotation of the plane of the scanning beam and a generator of functional signals, and the node for forming a flat scanning beam contains a magneto-optical crystal connected to the generator of functional signals and fixed inside the rotary ring, and an electric drive mechanically connected to the rotary ring and connected to the output of the block of rotation of the plane of the scanning § beam, the control input of which is connected “to another output of the synchronization unit, and the outputs are connected to the corresponding inputs of the recognition unit. Figure 1 2. The device according to π. 1, characterized in that the harmonic analyzer comprises a filter unit, the input of which is the input of the harmonic analyzer, a normalization unit and a maximum harmonic amplitude extraction unit, the inputs of which are connected to one of the outputs of the filter unit, the other outputs of which and the output of the maximum harmonic amplitude extraction unit are connected to the corresponding inputs of the normalization block, the output of which is the output of the harmonic analyzer.