WO2019187966A1

WO2019187966A1 - Magnetic information reader and method of controlling magnetic information reader

Info

Publication number: WO2019187966A1
Application number: PCT/JP2019/007978
Authority: WO
Inventors: 史彦二村; 上村　吉治
Original assignee: 日本電産サンキョー株式会社
Priority date: 2018-03-29
Filing date: 2019-03-01
Publication date: 2019-10-03
Also published as: JP2019175534A

Abstract

Provided are a magnetic information reader capable of speeding up an extreme value detection operation, and also reading of magnetic data as a consequence, and a method of controlling the magnetic information reader. A data processing unit 40 of the magnetic information reader includes: an A/D converter 28; a timing adjustment unit 26 for adjusting timing such that sampling is performed twice for each sampling period of the A/D converter 28; a data storage unit 29 for storing two items of digital data obtained in each sampling period, and sampling positions; an inclination calculation unit 301 for obtaining an inclination in each of the sampling periods from the two items of digital data and the positions; an inclination selection unit 302 for selecting two inclinations that are expressed by a positive sign and a negative sign; an approximate curve calculation unit 303 for obtaining an approximate curve on the basis of the selected two inclinations; and an extreme value calculation unit 304 for calculating an extreme value and an extreme value position on the basis of the calculated approximate curve.

Description

Magnetic information reader and method for controlling magnetic information reader

The present invention relates to a magnetic information reading device for reading magnetic information on a magnetic information recording medium such as a magnetic card recorded in a predetermined format (modulation method) and a method for controlling the magnetic information reading device.

A magnetic information reader, which is a magnetic card reader, reads F and 2F signals for “0” and “1” signals magnetically recorded on a magnetic card or the like by a predetermined modulation method, for example, a frequency modulation method, with a magnetic head.

The magnetic head reads magnetic data (magnetic signal, magnetic information) recorded by the F2F modulation method as an analog magnetic waveform signal.
In the magnetic information reader, an extreme value detection process is performed to detect the extreme values that are the peak and bottom of the magnetic waveform from the magnetic waveform signal, the output signal is inverted at the extreme value position, and the magnetic waveform is converted into a rectangular wave signal. Waveform shaping. This rectangular wave signal is a frequency-modulated (F2F modulated) signal and is demodulated by the F2F demodulator.

In recent magnetic information readers, an analog magnetic waveform signal is converted into digital data by an analog-digital (A (Analog) / D (Digital)) converter, and extreme value detection processing and subsequent processing are performed ( For example, see Patent Document 1).

In the magnetic information reader described in Patent Document 1, a magnetic waveform signal that is a read analog signal of a magnetic head is input to an A / D converter via an amplifier circuit. In the A / D converter, a process of sampling an analog signal at a predetermined sampling frequency and converting it into digital data is performed. The obtained digital data is temporarily stored in a storage device called a sampling data memory and then subjected to processing such as extreme value detection processing for obtaining the peak and bottom of the output signal.

JP 2013-211083 A

In the processing by the A / D converter as shown in Patent Document 1, since the sampling frequency is determined regardless of the level change of the analog signal, the sampling timing coincides with the peak or bottom that is the extreme value of the analog signal. Not always.
For this reason, various ideas have been applied to detect the extreme value (peak or bottom) of an analog signal with a small error.

For example, in the above example, a method of increasing the sampling frequency and increasing the number of times of sampling per unit time is known. In this case, since sampling is performed more finely, the peak (or bottom) of the level of the analog signal is easily detected.

However, in the above-described extreme value detection method for detecting the peak and the bottom, in order to increase the sampling frequency, the number of times of sampling increases dramatically, and the amount of sampled digital data increases.

For this reason, when various processes are performed based on the obtained digital data, a large-capacity sampling data memory capable of holding a large amount of data is required, which increases the cost of the sampling data memory. Furthermore, this method requires an A / D converter that performs sampling at high speed, and the other components are configured to withstand high-speed sampling, resulting in an increase in cost.

In the above extreme value detection method, the maximum value and the minimum value of the sampling data are detected, and the position is set as the extreme value (peak (peak), bottom (valley)) of the waveform. The position becomes a discrete value, and the extreme value detection lacks accuracy, and it is difficult to increase the extreme value detection accuracy.

Therefore, an object of the present invention is to provide a magnetic information reading apparatus that does not require high-performance hardware, a large-capacity memory, and the like and can increase the extreme value detection accuracy. It is another object of the present invention to provide a method for controlling a magnetic information reading apparatus that does not require high-performance hardware, a large-capacity memory, or the like, and can increase the extreme value detection accuracy.

In order to solve the above problems, a magnetic information reader of the present invention converts a magnetic head that reads magnetic data recorded on a magnetic information recording medium by a predetermined modulation method, and converts an output signal of the magnetic head into digital data. A data processing unit that demodulates the data, and the data processing unit samples an analog signal output from the magnetic head at a predetermined period and converts the analog signal into digital data; and A timing adjustment unit that adjusts timing so that sampling is performed twice at each sampling of the A / D converter, two digital data at each sampling and a data storage unit that stores a sampling position, and two at each sampling An inclination calculation unit that calculates the inclination at each sampling based on digital data and position, and the sign of the inclination is positive or negative An inclination selection unit that selects two inclinations, an approximate curve calculation unit that calculates an approximate curve based on the two selected gradients, and an extreme value calculation that calculates an extreme value and an extreme value position based on the calculated approximate curve And a demodulator for demodulating data read by the magnetic head based on the calculated position of the extreme value.

In order to solve the above problems, a control method for a magnetic information reading apparatus according to the present invention is a method for reading magnetic data recorded by a magnetic head on a magnetic stripe formed on a magnetic information recording medium by a predetermined modulation method. And a data processing step of converting the output signal of the magnetic head into digital data and demodulating the data, and the data processing step digitally samples the analog signal output from the magnetic head at a predetermined period. An analog-to-digital (A / D) conversion step for converting data, a timing adjustment step for adjusting the timing to sample twice at each sampling of the A / D conversion step, two digital data at each sampling and sampling Data storage step to store the position and each sampling time An inclination calculation step for obtaining an inclination at each sampling from two digital data and positions, an inclination selection step for selecting two inclinations with positive and negative signs of the inclination, and an approximate curve based on the two selected inclinations An approximate curve calculating step for calculating an extreme value and an extreme value position based on the calculated approximate curve; a demodulation step for demodulating data read by the magnetic head based on the calculated extreme value position; , Including.

In the present invention, the data processing unit that converts and processes the output signal of the magnetic head into digital data, the A / D converter samples the analog signal output from the magnetic head at a predetermined period and converts it into digital data, In addition, the timing is adjusted so that sampling is performed twice at each sampling of the A / D conversion, two digital data at each sampling and a sampling position are stored, and each of the two digital data and the position at each sampling is stored. Obtain the slope at the time of sampling, select two slopes with positive and negative slopes, find an approximate curve based on the two selected slopes, and find the extreme value and extreme value position based on the obtained approximate curve And the data read by the magnetic head is demodulated based on the calculated extreme value position. As a result, the sampling period of the analog signal may be coarse, so that high-performance hardware and a large-capacity memory are not required, and extreme value detection accuracy can be improved.

In the present invention, the A / D converter performs main sampling on the analog signal output from the magnetic head at a predetermined cycle, and sub-samples the main signal before or after the main sampling position (time). The data storage unit stores the main sampled main digital data and position at each sampling and the subsampled subdigital data and position at each sampling, and the slope calculation unit stores the data at the time of each sampling. It is preferable to obtain two slopes at the time of each sampling based on the main digital data and position, and the sub-digital data and position.

This sampling is generally performed at a constant cycle. However, in the present invention, it is possible to perform sampling twice per cycle in a time sufficiently shorter than the length of one cycle. Since two points are sampled at intervals, the slope at this time can be easily calculated. The extreme value position can be calculated if the respective slopes at two times are known. Therefore, the extreme position can be calculated from data of two periods (four samples).

In the present invention, the approximate curve is preferably represented by a quadratic function curve.
By adopting such a configuration, the position of the extreme value is a position where the linear function becomes zero, and can be expressed using the first-order coefficient and the zero-order coefficient of the polynomial. The first-order coefficient and the zero-order coefficient can be expressed by two slopes sandwiching extreme values and two sampling positions when the two slopes are obtained. Therefore, the extreme value calculation unit can calculate the position of the extreme value by using the two inclinations calculated by the inclination calculation unit and the two sampling positions when the two inclinations are obtained. It becomes possible.

As a result, the approximate expression can be easily obtained, the coefficient of the polynomial can be easily obtained, and the position of the extreme value (maximum value, minimum value) of the sampling data can be detected with a smaller error. become.

In the present invention, it is preferable that the sub-sampling timing for acquiring the sub-sampling data is set according to the switching interval of the track switching switch of the magnetic head. This makes it possible to easily set the sub-sampling timing in association with the main sampling timing.

As described above, according to the present invention, it is possible to increase the extreme value detection accuracy without requiring high-performance hardware or a large-capacity memory.

It is a block diagram which shows the structural example of the magnetic information reader which concerns on embodiment of this invention. It is a figure which shows the signal processing waveform of the principal part of the magnetic information reader of FIG. 1, FIG. 2 (a) shows a mode that the magnetic recording information recorded by the F2F modulation system is read as an analog signal, FIG. FIG. 2 (b) shows how the amplified analog signal is output to the sampling timing adjustment unit, and FIG. 2 (c) shows how the timing is adjusted so that it is sampled twice during each A / D conversion sampling. FIG. 2 (d) shows how the F2F signal, which is magnetic data read by the magnetic head, is demodulated. It is a figure which shows the structural example of the magnetic head and amplifier which read the magnetic data of the magnetic card in which the several magnetic track was formed. It is a figure which shows the structural example of the data calculation process part which is the principal part of the calculating part shown in FIG. It is a figure which shows the structural example of the sampling timing adjustment part which concerns on this embodiment. 2 is a flowchart for explaining an outline of an overall magnetic information reading operation of the magnetic information reading apparatus shown in FIG. 1. It is a figure for demonstrating the process which specifies the peak (maximum value) and peak position of an output signal. It is a flowchart of the process which specifies the peak (maximum value) and peak position of an output signal. It is a figure for demonstrating the process which specifies the bottom (minimum value) and bottom position of an output signal. It is a flowchart of the process which specifies the bottom (minimum value) and bottom position of an output signal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of magnetic information reader)
FIG. 1 is a block diagram showing a configuration example of a magnetic information reading apparatus according to an embodiment of the present invention. 2A to 2D are diagrams showing signal processing waveforms of the main part of the magnetic information reading apparatus in FIG.

In the present embodiment, a magnetic information reader that can be applied to a magnetic card reader that reproduces information recorded on a magnetic card MC, which is a magnetic information recording medium, will be described as an example. In this embodiment, an example in which F and 2F signals corresponding to “0” and “1” signals magnetically recorded by the frequency modulation method are read and reproduced will be described. However, the present technology is not limited to the F2F method, and various methods such as the F3F method, the NRZI method, and the MFM method can be applied.

The magnetic information recording medium of the present embodiment is a magnetic card MC, and the magnetic card MC includes a magnetic stripe MP on which magnetic data is recorded. The magnetic stripe MP is formed in an elongated strip shape. The magnetic stripe MP is formed along the longitudinal direction of the magnetic card MC formed in a rectangular shape. The magnetic card MC may contain an IC chip.

In the magnetic card MC, for example, ISO standard, JIS standard, and other types of magnetic recording formats are used. For example, a plurality of magnetic tracks are formed on the magnetic stripe MP, and magnetic information corresponding to the recording format is recorded on each magnetic track. Has been. The magnetic information (magnetic data) recorded on the magnetic track may be in the same magnetic recording format, or may be in a plurality of different magnetic recording formats, and determined in advance according to the specifications of the magnetic card MC. It has been.

As shown in FIG. 1, the magnetic information reader 10 includes a magnetic head 11, a card transport path 12, a card transport unit 13, a control unit 20, and a host device (host device) 50.

The magnetic head 11 reads, as an analog signal S11, magnetic recording information recorded on the magnetic card MC by, for example, the F2F modulation method as shown in FIG. FIG. 3 is a diagram illustrating a configuration example of a magnetic head and an amplifier that read magnetic data of a magnetic card on which a plurality of magnetic tracks are formed.

The magnetic head 11 rubs against the magnetic stripe MP to reproduce magnetic information recorded on the magnetic stripe MP and output an analog signal. In this embodiment, as shown in FIG. 3, the magnetic card MC is formed with three magnetic tracks # 1, magnetic track # 2, and magnetic track # 3 of magnetic data based on the ISO standard. Therefore, in the magnetic head 11, as shown in FIG. 3, the head portions 11-1, 11-2, and 11-3 correspond to the three magnetic tracks # 1, magnetic track # 2, and magnetic track # 3, respectively. Is provided. Each of the head portions 11-1, 11-2, and 11-3 is composed of at least a pair of magnetic cores arranged to face each other with a magnetic gap interposed therebetween. Further, on the output side of the head units 11-1, 11-2, 11-3 of the magnetic head 11, amplifiers 25-1, 25 corresponding to the head units 11-1, 11-2, 11-3 are provided. -2 and 25-3 are arranged. A sampling timing adjustment unit 26 is disposed on the output side of the amplifiers 25-1, 25-2, and 25-3.

In the card transport path 12, a magnetic head 11, a card transport section 13, and the like are arranged. Specifically, the magnetic card MC is transported along the card transport path 12 by the card transport unit 13, and the head units 11-1, 11-2, and 11-3 of the magnetic head 11 are connected to the transported magnetic card MC. The formed magnetic stripe MP is slid.

The card transport unit 13 transports the magnetic card MC along the card transport path 12 by driving the motor (M) 131 through the motor drive circuit (driver) 24. The motor (M) 131 is driven by the motor drive circuit 24 controlled by the control unit 20 and drives the card transport unit 13 to transport the magnetic card MC. As a control method of the motor (M) 131, for example, a PWM control method is adopted, and the motor (M) 131 is subjected to PWM control by the control unit 20.

The magnetic information reading apparatus 10 mainly includes a control unit 20, a storage unit 21, a calculation unit 22, and a data processing unit 40. Furthermore, in the present embodiment, a clock generation unit 23, a motor drive circuit 24, an amplifier 25, a sampling timing adjustment unit 26, a digital filter 27, an A / D converter 28, a data storage unit 29, and a data calculation processing unit 30 are provided. ing. The data processing unit 40 includes the amplifier 25, the sampling timing adjustment unit 26, the digital filter 27, the A / D converter 28, the data storage unit 29 of the storage unit 21, and the data of the calculation unit 22 among these components. An arithmetic processing unit 30 is used.

The data processing unit 40 has a function of converting the output signals of the head units 11-1, 11-2, and 11-3 of the magnetic head 11 into digital data and processing them.

The sampling timing adjustment unit 26 has a function of selecting the outputs of the head units 11-1, 11-2, and 11-3 of the magnetic head 11 as predetermined channels and supplying them to the A / D converter 28. . In the present embodiment, as shown in FIG. 2C, the timing is adjusted so that sampling is performed twice at each sampling of A / D conversion. The data storage unit 29 stores the two digital data and the sampling position at the time of each sampling. Then, the data arithmetic processing unit 30 obtains the slope at each sampling from the two digital data and the position at each sampling, selects the two slopes whose signs of the slope are positive and negative, and selects the selected two An approximate curve is obtained based on the inclination, an extreme value and an extreme value position are calculated based on the obtained approximate curve, and data read by the magnetic head is demodulated based on the calculated extreme value position.

The control unit 20 controls the overall operation of the magnetic information reader 10 and is connected to each component to exchange control signals and data. Specifically, the control unit 20 controls each unit of the magnetic information reading device 10 based on a control program and various data stored in the storage unit 21. In addition, the control unit 20 is connected to the host device 50 via a communication interface (not shown). The control unit 20 controls the entire magnetic information reading device 10 according to a command input from the host device 50 through a communication interface (not shown).

The storage unit 21 records programs and various data necessary for operation control of the entire apparatus. Further, in the present embodiment, a data storage unit 29 is provided. The data storage unit 29 stores a digital signal obtained by sampling the output signal (analog signal) output from the magnetic head 11 by the A / D converter 28 as sampling data. Specifically, the data storage unit 29 stores two digital data at the time of each sampling of A / D conversion and the sampling position.

The calculation unit 22 performs various calculation processes based on the data stored in the data storage unit 29. In the present embodiment, a data arithmetic processing unit 30 is provided.

The data calculation processing unit 30 processes the sampling data A / D converted by the A / D converter 28 based on the output signal of the magnetic head 11.

FIG. 4 is a diagram illustrating a configuration example of a data operation processing unit that is a main part of the operation unit illustrated in FIG. 1.
In this embodiment, as shown in FIG. 4, the data calculation processing unit 30 includes an inclination calculation unit 301, an inclination selection unit 302, an approximate curve calculation unit 303, an extreme value calculation unit 304, a demodulation unit 305, and a decoding unit 306. I have.

The inclination calculation unit 301 obtains the inclination K at each sampling from the two digital data y and the position (time) x at each sampling.

The inclination selection unit 302 selects two inclinations K1 and K2 whose signs of inclination are positive and negative. The inclination selection unit 302 selects, for example, one peak position (bottom position) xp (xb) and selects a position (time) x1 having a positive (negative) inclination and a position (time) x2 having a negative (positive) inclination. .

The approximate curve calculation unit 303 obtains an approximate function (curve) based on the two selected slopes. In the present embodiment, the approximate curve calculation unit 303 obtains a quadratic function approximate expression (y = ax ² + bx + c) as an approximate function. The slope y ′ of the position (time) x of the quadratic function approximation (y = ax ² + bx + c) can be obtained by y ′ = 2ax + b obtained by differentiating the quadratic function. Since the position (time) xp (xb) of the peak position (bottom position) is the position (time) at which the slope becomes 0, the coefficients a and b of the quadratic function are the two digital data y1 at the time of each sampling, It can be obtained from the position (time) x1, x2 of y2 and the slopes K1, K2 at the time of each sampling. The positions (time) x1 and x2 of the two digital data y1 and y2 at the time of each sampling and the slopes K1 and K2 at the time of each sampling are known values.

The extreme value calculation unit 304 calculates an extreme value and an extreme value position based on the value related to the calculated quadratic function (approximate curve). The extreme value calculation unit 304 is a position (time) x1, x2 of two digital data y1, y2 at the time of each sampling related to the coefficients a, b of the quadratic function given as known values by the quadratic curve calculation unit 303. Further, the peak (maximum value) and peak position, the bottom (minimum value), and the bottom position, which are extreme values, are calculated using the slopes K1 and K2 at the time of each sampling. Here, the peak indicates the maximum level of the output signal (F2F signal) of the magnetic head 11. The bottom indicates the minimum level of the output signal (F2F signal) of the magnetic head 11.

As described above, in this embodiment, the approximate curve is represented by a quadratic function curve. By adopting such a configuration, the position of the extreme value is a position where the linear function becomes zero and can be expressed using the first-order coefficient and the zero-order coefficient of the polynomial. The next coefficient can be expressed by two slopes K1 and K2 sandwiching extreme values, and two sampling positions (time) x1 and x2 when the two slopes are obtained. Then, the extreme value calculation unit 304 calculates the position of the extreme value at the time of two samplings when the two inclinations K1 and K2 calculated by the inclination calculation unit 301 and the two inclinations K1 and k2 are obtained. It can be calculated using the positions x1 and x2.

As a result, the approximate expression can be easily obtained and the coefficient of the polynomial can be easily obtained, and the position of the extreme value (maximum value, minimum value) of the sampling data can be detected more efficiently and with smaller errors. It is possible to do.

Based on the position of the extreme value calculated by the demodulation unit 305 and the extreme value calculation unit 304, the F2F signal, which is magnetic data read by the magnetic head 11, is demodulated as shown in FIG.

The decoding unit 306 decodes the F2F signal demodulated by the demodulation unit 305 and converts it into “0” and “1” data. The decoding unit 306 converts “0” and “1” data into magnetic data (ASCII), and transmits the converted data to the higher-level device 50 through the communication interface.

The clock generator 23 supplies a clock signal CLK that is a time reference in the magnetic information reader 10. In the present embodiment, the clock generator 23 supplies a sampling clock signal SPCK serving as a sampling time reference input to the A / D converter 28. Further, a reference clock that serves as a drive pulse for the motor 131 is also supplied. The clock generator 23 is supplied to the A / D converter 28 by the sampling timing adjustment unit 26 at each sampling of the A / D converter 28, and continues to a magnetic head 11 (- A sampling clock signal SPCK is supplied so as to sample the read data 1 to -3).

The motor drive circuit 24 inputs a drive pulse to the motor 131 based on the motor control pulse input from the control unit 20 and drives the motor 131.

The amplifier 25 (-1 to -3) amplifies the analog signal S11 read out by the magnetic head 11 to an appropriate level, and the amplified analog signal S25 as shown in FIG. 26. The amplifier 25 (-1 to -3) can be configured to have an automatic gain control (AGC) function.

The sampling timing adjustment unit 26 adjusts the input timing of the read data of the magnetic head 11 (-1 to -3) to the A / D converter 28 so that sampling is performed twice at each sampling of the A / D converter 28. .

FIG. 5 is a diagram illustrating a configuration example of the sampling timing adjustment unit according to the present embodiment.
The sampling timing adjustment unit 26 in FIG. 5 is configured to read the magnetic data recorded on the three magnetic tracks # 1, # 2 and # 3 by the magnetic heads 11-1, 11-2 and 11-3. It corresponds. In FIG. 5, the amplifier 25 is omitted in order to simplify and understand the drawing.

5 includes a multiplexer 261. The sampling timing adjustment unit 26 shown in FIG. In this example, one magnetic track (magnetic head) is connected to two channels CH. Magnetic track # 1 is connected to channels CH1 and CH4, magnetic track # 2 is connected to channels CH2 and CH5, and magnetic track # 3 is connected to channels CH3 and CH6. In this connection state, when a command for A / D conversion from the channels CH1 to CH6 is issued for each cycle to the A / D converter 28, the magnetic tracks # 1, # 2, and # 3 are shown in FIG. As shown, two sampling results are obtained and the time between the two samplings is sufficiently short.

Here, sampling for the output data of the main channels CH1, CH2, and CH3 is referred to as main sampling MSPL, and sampling for the output data of the channels CH4, CH5, and CH6 continuous thereto is referred to as subsampling SSPL.

This makes it possible to easily set the timing of the sub-sampling SSPL in association with the timing of the main sampling MSPL. In this configuration, the magnetic head 11 is connected so that, for example, the magnetic data of the magnetic tracks # 1, # 2, and # 3 are selectively input to the A / D converter 28 via the two channels CH, respectively. ing. The multiplexer 261 and the A / D converter 28 of the sampling timing adjusting unit 26 circulate in the order of CH1, CH2, CH3, CH4, CH5, and CH6 over all channels CH1 to CH6 every cycle so as to perform A / D conversion. The main digital data and position, and the sub-digital data and position, which are two sampling results, can be obtained for each of the magnetic tracks # 1, # 2, and # 3. The inclination calculation unit 301 can calculate an inclination corresponding to each magnetic track using the acquired main digital data and position, and sub-digital data and position.

As described above, in this embodiment, the timing of the sub-sampling SSPL for acquiring the sub-sampling data is set according to the channel switching interval of the multiplexer 261 as a track switching switch of the magnetic head.

As shown in FIG. 2C, the A / D converter 28 samples the analog signal S25 read by the magnetic head 11 and amplified by the amplifier 25 at a predetermined frequency to convert it into a digital signal. The digital signal is output to the data storage unit 29 via the digital filter 27. In the present embodiment, the sampling interval (frequency) is not particularly limited, but may be smaller than the conventional sampling number, for example.

As described above, the A / D converter 28 performs main sampling MSPL on the analog signal output from the magnetic head 11 (-1 to -3) at a predetermined cycle and after the position of the main sampling MSPL (or Sub-sampling SSPL is performed at the previous position (time)) and converted into main digital data and sub-digital data. The data storage unit 29 stores main digital data and position subjected to main sampling MSPL and sub-digital data and position subjected to sub-sampling SSPL at the time of each sampling. The inclination calculation unit 301 obtains two inclinations K1 and K2 at each sampling from the main digital data and position at each sampling and the sub-digital data and position.

Sampling by the A / D converter 28 is generally performed at a constant period, but in this embodiment, sampling is performed twice per period in a time sufficiently shorter than the length of one period. Make it. When two points are sampled at short intervals, the change in the slope between the sampling positions is slight, so it can be assumed that the slope between them is constant, and the slope at the time of sampling can be easily calculated based on this assumption. . The extreme value position can be calculated if the slopes at the two positions (time) are known. Therefore, the extreme position can be calculated from data of two periods (four samples).

The digital filter 27 performs noise removal processing of the digital signal converted by the A / D converter 28 and stores it as sampling data in the data storage unit 29 together with the position at the time of sampling. An analog filter may be disposed between the magnetic head 11 and the A / D converter 28 instead of the digital filter 27.

(Control flow of magnetic information reader)
FIG. 6 is a flowchart for explaining the outline of the overall magnetic information reading operation of the magnetic information reading apparatus 10 shown in FIG.

First, the control unit 20 activates the motor 131 of the card transport path 13 through the motor drive circuit 24 (step ST1), and transports (moves) the magnetic card MC relative to the magnetic head 11 to thereby move the magnetic card MC. Magnetic information recorded in the magnetic stripe MP by the F2F modulation method is read (step ST2). Thereby, the conveyance of the magnetic card MC is completed (step ST3), and the control unit 20 stops the motor 131 of the card conveyance path 13 through the motor drive circuit 24 (step ST4).

In step ST2, the analog signal S11 (S11-1, S11-2, S11-3) read by the magnetic head 11 (each head unit 11-1, 11-2, 11-3) is supplied to the amplifier 25 ( 25-1, 25-2, 25-3) and amplified to an appropriate level, and the sampling timing adjustment unit 26 samples the magnetic head 11 (each head unit 11-1, 11-2) so that sampling is performed twice at each sampling. , 11-3) the input timing of the read data to the A / D converter 28 is adjusted and input to the A / D converter 28.
In the A / D converter 28, the data is read by the magnetic head 11 (each head unit 11-1, 11-2, 11-3) and amplified by the amplifier 25 (25-1, 25-2, 25-3) The sampled analog signal S25 (S25-1, S25-2, S25-3) is sampled twice continuously at intervals sufficiently shorter than one sampling period at each sampling and converted into a digital signal. The data is stored in the data storage unit 29 via the digital filter 27.

Thereafter, the data calculation processing unit 30 of the calculation unit 22 calculates the peak, peak position, bottom, and bottom position based on the A / D conversion value acquired in step ST2 (step ST5). Based on the calculated peak and peak position (or bottom, bottom position), the data arithmetic processing unit 30 demodulates the F2F signal that is magnetic data read by the demodulator 305 with the magnetic head 11 (step ST6). Then, the decoding unit 306 decodes the F2F signal demodulated by the demodulation unit 305 and converts it into “0” and “1” data (step ST7), and transmits the converted magnetic data to the host device 50 (step ST7). Step ST8).

Hereinafter, the magnetic information acquisition method in step ST2 and the calculation method of the peak, peak position, bottom, and bottom position in step ST5 will be specifically described.

(Process for specifying the peak position Pv and the bottom position Bv of the output signal of the magnetic head 11)
FIG. 7 is a diagram for explaining processing for specifying a peak (maximum value) and a peak position of an output signal. FIG. 8 is a flowchart of processing for specifying the peak (maximum value) and peak position of the output signal. FIG. 9 is a diagram for explaining processing for specifying the bottom (minimum value) and bottom position of the output signal. FIG. 10 is a flowchart of processing for specifying the bottom (minimum value) and bottom position of the output signal.

The data calculation processing unit 30 performs a process of specifying the peak position Pv and the bottom position Bv based on the A / D conversion value obtained from the analog signal S11 read by the magnetic head 11, and the specified peak position Pv and bottom position The F2F signal is demodulated based on Bv.

(Calculate the maximum value)
The output signal (F2F) signal of the magnetic head 11 (each head unit 11-1, 11-2, 11-3) is amplified to an appropriate level by the amplifier 25 (25-1, 25-2, 25-3), The input timing of the read data of the magnetic head 11 (each head unit 11-1, 11-2, 11-3) to the A / D converter 28 is determined so that the sampling timing adjusting unit 26 samples twice at each sampling. It is adjusted and input to the A / D converter 28. In the A / D converter 28, the data is read by the magnetic head 11 (each head unit 11-1, 11-2, 11-3) and amplified by the amplifier 25 (25-1, 25-2, 25-3) The analog signal S25 (S25-1, S25-2, S25-3) is sampled twice continuously at intervals sufficiently shorter than one sampling period at each sampling and converted into a digital signal (step ST11). . In this case, the multiplexer 261 and the A / D converter 28 of the sampling timing adjustment unit 26 circulate in the order of CH1, CH2, CH3, CH4, CH5, and CH6 over all channels CH1 to CH6 every cycle. A command is issued to perform D / D conversion, and the main digital data y11 and position (time) x11, which are two sampling results, and sub-digital data y12 and position for each magnetic track # 1, # 2, # 3 (Time) x12 is acquired. After the noise is removed via the digital filter 27, the converted digital signal is stored in the data storage unit 29 together with the sampling position (time) x as sampling data y. Specifically, two digital data y are obtained as sampling data by the A / D converter 28 and stored in the data storage unit 29 in association with the position (time) x.

The data calculation processing unit 30 calculates and processes the sampling data y and the position (time) x stored in the data storage unit 29. First, the inclination calculation unit 301 uses the acquired main digital data y11 and position x11 and sub-digital data y12 and position x12 stored in the data storage unit 29 to each magnetic track # 1, # 2, # 3. Is calculated (step ST12). Here, the magnetic track # 1 to which the channels CH1 and CH4 are connected will be described, but the other magnetic tracks # 2 and # 3 can be calculated by the same method.

For example, as shown in FIG. 7, the position (time) and amplitude of the main sampling of channel CH1 at position (time) x1 are (x11, y11), and the position (time) and amplitude of subsampling of channel CH4 are (x12 , Y12). Similarly, the position (time) and amplitude of the main sampling of the channel CH1 at the position (time) x2 are (x21, y21), and the position (time) and amplitude of the sub-sampling of the channel CH4 are (x22, y22).

In such a state, the slope K1 at the position (time) X1 can be obtained by the following equation.

[Equation 1]
K1 = (y12−y11) / (x12−x11) (1)

Similarly, the slope K2 at the position (time) X2 can be obtained by the following equation.

[Equation 2]
K2 = (y22−y21) / (x22−x21) (2)

Next, the inclination selecting unit 302 selects a position (time) x1 having a positive inclination and a position (time) x2 having a negative inclination with one peak position xp interposed therebetween (step ST13). In the selection process in step ST13, if the slope is positive (NO in step ST14), the process waits for a predetermined sampling interval (step ST15), returns to the process in step ST12, and reads the next sampling data. In the selection process, when the slope is negative (YES in step ST14), an approximate curve is obtained based on the two slopes selected by the approximate curve calculation unit 304 (step ST16), and the approximation calculated by the extreme value calculation unit 304 is obtained. An extreme value and an extreme value position are calculated based on the curve (step ST17). In the process of step ST17, the peak position xp is calculated using the position information of the positive slope that has already been A / D converted.

In step ST16, the approximate curve calculation unit 303 obtains a quadratic function approximate expression (y = ax ² + bx + c) as an approximate function. The slope y ′ of the position (time) x of the quadratic function approximation formula (y = ax ² + bx + c) can be obtained by the following formula obtained by differentiating the quadratic function.

[Equation 3]
y ′ = 2ax + b (3)

Since the peak position (time) xp is the position (time) at which the slope becomes 0, it can be expressed by the coefficients a and b from the expression (3) as in the following expression (4).

[Equation 4]
2axp + b = 0
xp = −b / 2a (4)

Furthermore, the relationship between the slopes K1 and K2 and the coefficients a and b at the positions (time) x1 and x2 can be expressed as follows.

[Equation 5]
2ax1 + b = K1 (5)
2ax2 + b = K2 (6)

By subtracting the equation (6) from the equation (5), the coefficient a can be expressed by the slopes K1, K2, and the position (time) x1, x2 as in the equation (7).

[Equation 6]
2ax1-2ax2 = K1-K2
a = (K1-K2) / 2 (x1-x2) (7)

The equation (7) is substituted into the equation (5), and the coefficient b can be expressed by the slopes K1, K2, and the position (time) x1, x2 as in the equation (8).

[Equation 7]
2 {(K1-K2) / 2 (x1-x2)} x1 + b = K1
b = (− K1 × 2 + K2 × 1) / (x1−x2) (8)

The peak position xp is given by equation (9) in association with equations (4), (7), and (8).

[Equation 8]
xp =-{(-K1x2 + K2x1) / (x1-x2)} / 2 {(K1-K2) / 2 (x1-x2)}
xp = (− x1K2 + x2K1 / (K1−K2) (9)

X1 and x2 are known at the sampling position (time), and the slopes K1 and K2 have also been calculated from the known sampling values from the expressions (1) and (2), and the peak position can be calculated from the expression (9).

Next, the bottom (minimum value) and the bottom position Bv are obtained. Note that the calculation processing for obtaining the bottom position is basically performed in the same manner as the calculation processing described in relation to Equations 1 to 8 above. Therefore, detailed description thereof is omitted below. However, so-called Yamatani and positive and negative are reversed. In the following description, the same reference numerals as those in the above description are used for easy understanding.

As described above, after specifying the peak (maximum value) and the peak position Pv, the data calculation processing unit 30 proceeds to the process of specifying the bottom (minimum value) and the bottom position Bv. Hereinafter, the peak position Pv and the bottom position Bv are alternately specified by repeating the processes shown in FIGS.

(Calculate the minimum value)
The output signal (F2F) of the magnetic head 11 (each head unit 11-1, 11-2, 11-3) is amplified to an appropriate level by the amplifier 25 (-1 to -3), and the sampling timing adjusting unit 26 The input timing of the read data of the magnetic head 11 (each head portion 11-1, 11-2, 11-3) to the A / D converter 28 is adjusted so that sampling is performed twice at each sampling, and the A / D Input to the converter 28. In the A / D converter 28, the data is read by the magnetic head 11 (each head unit 11-1, 11-2, 11-3) and amplified by the amplifier 25 (25-1, 25-2, 25-3) The analog signal S25 (S25-1, S25-2, S25-3) is sampled twice consecutively at intervals sufficiently shorter than one sampling period at each sampling and converted into a digital signal (step ST21). .
In this case, the multiplexer 261 and the A / D converter 28 of the sampling timing adjustment unit 26 circulate in the order of CH1, CH2, CH3, CH4, CH5, and CH6 over all channels CH1 to CH6 every cycle. A command is issued to perform D / D conversion, and the main digital data y11 and position (time) x11, which are two sampling results, and sub-digital data y12 and position for each magnetic track # 1, # 2, # 3 (Time) x12 is acquired. After the noise is removed via the digital filter 27, the converted digital signal is stored in the data storage unit 29 together with the sampling position (time) x as sampling data y. Specifically, two digital data y are obtained as sampling data by the A / D converter 28 and stored in the data storage unit 29 in association with the position (time) x.

The data calculation processing unit 30 calculates and processes the sampling data y and the position (time) x stored in the data storage unit 29. First, the inclination calculation unit 301 uses the acquired main digital data y11 and position x11 and sub-digital data y12 and position x12 stored in the data storage unit 29 to each magnetic track # 1, # 2, # 3. Is calculated (step ST22). Here, the magnetic track # 1 to which the channels CH1 and CH4 are connected will be described, but the other magnetic tracks # 2 and # 3 can be calculated by the same method.

For example, as shown in FIG. 9, the position (time) and amplitude of the main sampling of the channel CH1 at the position (time) x1 are (x11, y11), and the position (time) and amplitude of the subsampling of the channel CH4 are (x12 , Y12). Similarly, the position (time) and amplitude of the main sampling of the channel CH1 at the position (time) x2 are (x21, y21), and the position (time) and amplitude of the sub-sampling of the channel CH4 are (x22, y22).

In such a state, the slope K1 at the position (time) X1 can be basically obtained by the above equation (1). Similarly, the slope K2 at the position (time) X2 can be obtained by the above equation (2).

Next, the inclination selecting unit 302 selects a position (time) x1 having a negative inclination and a position (time) x2 having a negative inclination with one bottom position xb interposed therebetween (step ST23). If the slope is negative (NO in step ST24) in the selection process in step ST23, the process waits for a predetermined sampling interval (step ST25), returns to the process in step ST22, and reads the next sampling data. In the selection process, if the slope is positive (YES in step ST24), an approximate curve is obtained based on the two slopes selected by the approximate curve calculation unit 304 (step ST26), and the approximation calculated by the extreme value calculation unit 304 is obtained. An extreme value and an extreme value position are calculated based on the curve (step ST27). In the process of step ST27, the bottom position xb is calculated using the position information of the positive inclination that has already been A / D converted.

Hereinafter, after the sampling data is processed to the end, the demodulator 305 is based on the obtained local maximum value and peak position Pv, local minimum value and bottom position Bv based on the number of peak positions Pv and bottom positions Bv of the output signal of the magnetic head 11. The F2F signal, which is magnetic data read by the magnetic head 11, is demodulated. Then, the decoding unit 306 decodes the F2F signal demodulated by the demodulation unit 294 and converts it into “0” and “1” data, and further transmits the converted magnetic data to the host device 50.

(Main effects of this embodiment)
As described above, in this embodiment, the data processing unit 40 that converts the output analog signal (F2F signal) of the magnetic head 11 into digital data and processes it is output from the magnetic head 11 by the A / D converter 28. The analog signal is sampled at a predetermined cycle and converted into digital data, and the timing is adjusted so that the sampling timing adjusting unit 26 samples twice at each sampling of the A / D conversion. The digital data and the sampling position are stored in the data storage unit 29, and in the data calculation processing unit 30, the inclination calculation unit 301 obtains the inclination at each sampling from the two digital data and positions at each sampling, and the inclination selection unit 302. Select two slopes with the sign of the slope being positive and negative, and calculate the approximate curve Approximate curve based on the two slope section 303 selects, for example, obtains the quadratic approximate expression ^{(y = ax 2 + bx +} c), calculating an extreme value and extreme positions on the basis of the approximate curve extreme calculating unit 304 has determined Then, the demodulator 305 demodulates the data read by the magnetic head based on the calculated extreme value position.

As a result, according to the present embodiment, the sampling period of the analog signal may be coarse, and high-value detection accuracy can be improved without requiring high-performance hardware or a large-capacity memory.

Further, in this embodiment, the processing speed of the extreme value detection calculation is improved, and as a result, the processing time of reading out magnetic data can be shortened. That is, for example, in order to realize a magnetic information reader capable of increasing the extreme value detection accuracy, a method of detecting an extreme value by determining a coefficient of an approximate curve using a so-called sweeping method may be adopted. Conceivable. However, since the product quotient operation is several times heavier than the sum / difference operation, the sweep method, which requires a large amount of product quotient operation, is not suitable for computing units such as microcontrollers used for integration. The calculation is not a light load. Therefore, it takes time to complete the extreme value detection, and as a result, it may take time to complete the reading of the magnetic card. In contrast, when the extreme position is calculated using this method, the required calculation (particularly product) is less than the sweep method, which increases the processing speed of the extreme value detection calculation, resulting in magnetic Data read processing time can be shortened.

In the present embodiment, the A / D converter 28 performs main sampling on the analog signal output from the magnetic head 11 at a predetermined period, and sub-samples at a position (time) before or after the main sampling position. The data storage unit 29 stores the main sampled main digital data and position and the subsampled sub digital data and position at the time of each sampling, and the inclination calculation unit 301 stores the main digital data and the sub digital data. The two slopes at each sampling are obtained from the main digital data and position at each sampling and the sub-digital data and position.

Sampling by the A / D converter 28 is generally performed at a constant period, but in this embodiment, sampling is performed twice per period in a time sufficiently shorter than the length of one period. Since two points are sampled at short intervals, it is possible to easily calculate the slope at the time of sampling assuming that the slope between them is constant. The extreme value position can be calculated if the respective slopes at two times are known. Therefore, the extreme position can be calculated from data of two periods (four samples).

In this embodiment, the approximate curve can be represented by a quadratic function curve. By adopting such a configuration, the position of the extreme value is a position where the linear function becomes zero and can be expressed using the first-order coefficient and the zero-order coefficient of the polynomial. The next coefficient can be expressed by two slopes sandwiching the extreme values, and two sampling positions when the two slopes are obtained, and the extreme value calculation unit 304 calculates the extreme value position by the slope. The calculation can be performed using the two inclinations calculated by the calculation unit 304 and the two sampling positions when the two inclinations are obtained.

As a result, the approximate expression can be easily obtained and the coefficient of the polynomial can be easily obtained, and the position of the extreme value (maximum value, minimum value) of the sampling data can be detected more efficiently and with smaller errors. It becomes possible to do.

In this embodiment, the subsampling timing for acquiring the subsampling data is set according to the switching interval of the track switching switch of the magnetic head.

This makes it possible to set the sub-sampling timing in association with the main sampling timing. Usually, a plurality of magnetic tracks # 1, # 2, and # 3 are formed on the magnetic stripe MP of the magnetic card MC that is a magnetic information recording medium. Correspondingly, the magnetic head 11 can be connected so that, for example, magnetic data of each magnetic track is selectively input to the A / D converter 28 via two channels. The A / D converter 28 receives a command to cycle through all the channels in order for every channel and perform A / D conversion, and the main digital data and position which are two sampling results for each magnetic track, In addition, the sub-digital data and position can be acquired, and the tilt calculation unit 301 can calculate the tilt corresponding to each magnetic track using the acquired main digital data and position, and the sub-digital data and position. It becomes possible.

(Other embodiments)
The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited to this, and various modifications can be made without departing from the scope of the present invention.

In the above-described embodiment, as shown in FIG. 1, a configuration in which the sampling timing adjustment unit 26 is connected to the output side of the amplifier 25 is employed, but the sampling timing adjustment unit 26 is connected to the input side of the amplifier 25. It is also possible to adopt the configuration that has been described.

The magnetic head 11 is a magnetic head that reproduces magnetic information recorded on each of the three magnetic tracks, but is not limited to this. For example, the magnetic head may have one head portion. Furthermore, a magnetic head having a function of writing magnetic information to the magnetic stripe MP of the magnetic card MC may be used.

In the embodiment described above, the decoding unit 306 decodes the F2F signal demodulated by the demodulation unit 305 and converts it into “0” and “1” data, and converts the “0” and “1” data into magnetic data (ASCII). However, the data “0” and “1” are transmitted to the host device 50, and the host device 50 transmits the 0 and “1” data to the magnetic data (ASCII II). It is also possible to configure so as to convert to

In the embodiment described above, the magnetic card MC can be a rectangular vinyl chloride card having a thickness of about 0.7 to 0.8 mm, but the magnetic card MC has a thickness of 0.18 to A PET (polyethylene terephthalate) card of about 0.36 mm, a paper card with a predetermined thickness, or the like may be used. The magnetic information recording medium to which the present invention is applied may be a medium other than a card.

Approximation may be performed using second-order or higher-order function approximation other than the least square method, approximation using a spline function, approximation using a sampling (sinc) function, or the like.

Furthermore, although the magnetic card reader described above is a motor drive type, a manual card reader such as a swipe type may be used.

MC: magnetic card (magnetic information recording medium), 10: magnetic information reader, 11, 11-1 to 11-3 ... magnetic head, 12 ... card transport path, 13 ... card Transport unit 131... Motor, 20... Control unit, 21... Storage unit, 22. 1 to 25-3: amplifier, sampling timing adjustment unit, 27: digital filter, 28 ... A / D converter, 29 ... data storage unit, 30 ... data operation processing unit, 301 ... Inclination calculation unit 302. Inclination selection unit 303 303 Approximation curve calculation unit 304 304 Extreme value calculation unit 305 Demodulation unit 306 Decoding unit 40 -Data processing unit, 50 ... host device.

Claims

An image processing apparatus that detects a rotation angle on an image of a rectangular medium using a digital image,
A projection generation unit that generates a projection of pixel values by luminance projection for each of a horizontal axis and a vertical axis of the image data of the rectangular medium;
For each of the projection onto the horizontal axis and the projection onto the vertical axis, an end point detection unit that determines both end points of the projection pattern of the projection waveform;
A processing target cutout unit that cuts out first image data using a rectangular portion including four end points on the left, right, top, and bottom as a processing target;
An image adjusting unit that generates third image data obtained by superimposing the first image data obtained by cutting out the medium and the second image data obtained by rotating the first image data by 180 degrees with respect to the area to be processed;
For the third image data in the area to be processed, at least two parallel lines are drawn parallel to the horizontal axis or the vertical axis at positions passing through the area to be processed, and the rectangular shape on each parallel line is drawn. A medium edge point deviation calculating unit for obtaining an edge position of the medium and obtaining an edge interval between the two edge positions;
An angle calculation unit that calculates an inclination angle from the edge interval and a separation distance between the two parallel lines;
An image processing apparatus comprising:
The processing target area image adjustment unit,
2. The third image data is generated by taking an average of each pixel value of the first image data and the second image data obtained by rotating the first image data by 180 degrees. Image processing device.
An image processing method for detecting a rotation angle on an image of a rectangular medium using a digital image,
A projection generation step of generating a projection of pixel values by luminance projection for each of a horizontal axis and a vertical axis of the image data of the rectangular medium;
For each of the projection onto the horizontal axis and the projection onto the vertical axis, an endpoint detection step for determining both end points of the projection pattern of the projection waveform;
A processing target cutout step of cutting out the first image data using a rectangular portion composed of four end points on the left, right, top and bottom as processing targets;
An image adjustment step for generating third image data in which the first image data obtained by cutting out the medium and the second image data obtained by rotating the first image data by 180 degrees are superimposed on the processing target area;
For the third image data in the area to be processed, at least two parallel lines are drawn parallel to the horizontal axis or the vertical axis at positions passing through the area to be processed, and the rectangular shape on each parallel line is drawn. A medium edge point deviation calculating step for determining an edge position of the medium and determining an edge interval between the two edge positions;
An angle calculating step of calculating an inclination angle from the edge interval and a distance between the two parallel lines;
An image processing method comprising:
In the image adjustment step,
The third image data is generated by taking an average of each pixel value of the first image data and the second image data obtained by rotating the first image data by 180 degrees. Image processing method.