JPH05242295A - Image reader for card - Google Patents

Abstract

PURPOSE:To solve such problem that an embossed character on a black card cannot be read by a conventional image reading method considering 'white emboss reading'. CONSTITUTION:Two kinds of image data are generated(frame memory 107) by switching the light emission strength of a LED light source 101 which irradiates a card to the light emission strength for 'white emboss reading' setting a white card as reference or the light emission strength for 'black emboss reading' setting a black card as reference at every line period of an image sensor 103, and it is decided whether the card is the white card or the black card by extracting(feature extraction part 110) the feature of the base color of the card from those two kinds of image data, and the image data adaptive for the base color can be selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cashing cache in an automatic transaction device (ATM) used in financial institutions.
The present invention relates to an image reading device for cards such as cards.

[0002]

2. Description of the Related Art Generally, in ATMs and CDs installed in financial institutions such as banks, a card with a magnetic stripe called a cashing card is used to verify the identity of the customer during the transaction. .. Customer uses this card
When the TM or the like is operated, based on the information stored in the magnetic stripe of the card, the transaction desired by the customer, that is, deposit, withdrawal, transfer, etc., is performed. At that time, in addition to this transaction work, the characters convexly processed on the cashing card, that is, the information such as the account number and the name recorded in the embossed characters are printed inside the ATM device, and one sheet is printed. In addition to providing the customer with a transaction statement, the other is kept by the financial institution as proof of the transaction. Generally, as a printing method of this embossed character, a pressure-sensitive method in which a pressure-sensitive paper is applied to the embossed character area and the roller is pressed against the pressure-sensitive paper has been adopted recently. Card image readers have become mainstream in which the image data obtained by reading is subjected to various kinds of image processing, printed out by a printer, and the printed matter is used for transaction work.

FIG. 2 is a block diagram showing the structure of a conventional card image reading apparatus. In the figure, 200 is a card being read, 201 is an LED light source composed of an LED array, 202 is a converging rod lens array, 2
03 is a one-dimensional image sensor, 204 is a sensor drive unit,
Reference numeral 205 is an amplifier circuit, 206 is an analog / digital conversion circuit (hereinafter referred to as an A / D conversion circuit), 207 is a binarization processing unit, 208 is a printer unit, and 209 is an LED drive circuit.

When the card 200 is conveyed in the direction of the arrow 211 by a conveying means (not shown) and comes under the image sensor 203, the card is irradiated with the light emitted from the LED light source 201.
Surface is illuminated. The LED light source 201 is connected to the LED drive circuit 209, and the
The driving voltage supplied to the light source is set so as not to saturate the read image data of the card having the whitest background color of the card among various kinds of cards.

Reflected light from the card surface is imaged on the image sensor 203 via the rod lens array 202. The imaged reflected light is photoelectrically converted in the image sensor 203 under the control of the sensor driving unit 204.
The weak read signal photoelectrically converted is amplified to a predetermined level by the amplifier circuit 205, and the A / D conversion circuit 206 of the next stage is amplified.
Is supplied to. This A / D conversion circuit converts a read signal (analog signal) into, for example, 8 bits (256 pixels) per pixel.
It is converted into a digital signal representing multi-valued density of (gradation) and supplied to the binarization processing unit 207 in the next stage.

In the binarization processing section, a γ correction circuit (not shown) corrects the difference in density balance between the background color of the card and the read image, and further, pseudo gradation processing for gradation printing, for example, The binarization process is performed by the dither process, the error diffusion process, and the like. After that, the printer unit 208 prints out by a printer of, for example, a thermal recording system, and uses this as an image image of the card.

The image image of the card handled here is
It is not a letter or image on the paper surface but an image of embossed letters that forms a convex shape, and the tip of the protrusion has a whitish card that is not treated with black or blue ink, or the embossed letters are processed in the same color as the background It is an image of the existing card. Therefore, when read normally, the boundary line between the embossed character and the background becomes unclear, and the embossed character becomes difficult to read. Therefore, irradiate the card with a light source that has a predetermined angle with respect to the surface of the card, and directly reflect from the card surface and the amount of specular reflection light and shadow light generated from the relationship between the irradiation angle and the convex shape of the embossed characters. The difference in level with the amount of reflected light is directly expressed as the print density difference of the printer and is used as an image image.

[0008]

However, in recent financial institutions, a wide variety of design cards ranging from whitish cards to blackish cards (hereinafter referred to as white cards or black cards) are distributed. As a result, the conventional image reading method has obtained a satisfactory image image for a card whose background color is relatively light, but a legible image image for a black card. The problem is that it is difficult. The reason is that the conventional image-reading optical system changes the emission intensity of the LED light source that illuminates the card surface,
This is because, regardless of the type of card, the light emission is always based on the white card as a reference. (Hereinafter, reading the white card's embossed letters is "white embossed reading", and reading the black card's embossed letters is "black embossed reading".
Called)

As a result, in a card with a light background color, the level difference between the light reflected from the LED light source and the amount of specular reflection or shadow generated from the shape of the convex embossed characters and the amount of light reflected from the card surface appears to some extent, which is satisfactory for the time being. Although an image image that can be obtained is obtained, the level difference and the absolute amount of the specular reflection light or the shadow generated from the shape of the card and the direct reflection light amount on the card surface due to the insufficient irradiation light amount of the LED light source on the black card There is a problem in that the image image of the final printout is crushed into black and the embossed character cannot be read because it is so small.

The present invention solves the problem that the embossed characters of the black card cannot be read in the conventional image reading in consideration of the "white embossed reading", and the image reading of all cards from the white card to the black card can be performed. It is an object of the present invention to provide an image reading device for a card that enables it.

[0011]

In order to solve the above-mentioned problems, an image reading device for a card according to the present invention comprises:
A card that includes an optical system including a line light source and an image sensor, a signal processing system including an amplifier circuit, an A / D conversion circuit, and the like, and reads an image image of a medium to be read such as a cashing card in which convex embossed characters are engraved. In the image reading device, the light emission intensity of the line light source in the optical system is synchronized with the reading line period of the image sensor to switch between the emission intensity based on the white card and the emission intensity based on the black card to emit light. A means for storing image data representing two kinds of multi-valued densities obtained from the two kinds of emission intensities; a feature extracting means for extracting a background color feature of the card from the two kinds of image data; One of the two types of image data is selected based on the feature extraction result by the feature extraction means. To.

At this time, if the feature extracting means counts the frequency of the density values from the two types of image data to extract the frequency distribution of the respective density values, the background color of the card can be obtained by a simple method. Can be extracted well.

[0013]

In the card image reading apparatus constructed as described above, the "white embossed reading" is performed with the white light as a reference for the emission intensity of the line light source that illuminates the surface of the card for each line cycle of the image sensor. Two types of image data are obtained alternately line by line by switching between the light emission intensity for scanning and the emission intensity for "black emboss reading" based on the black card. By extracting the background color characteristics of the card from these two types of image data, it is determined whether the card is a whitish card (white card) or a blackish card (black card), and based on this determination result, Of the two types of image data, the image data that is more suitable for the background color of the card is selected. Therefore, it is possible to optimally read the images of all cards from white cards to black cards, and the above problems are solved.

[0014]

1 is a block diagram showing the construction of an embodiment of an image reading apparatus for a card according to the present invention. In the figure, 100 is a caching card as a medium to be read on which convex embossed characters are engraved, 101 is an LED array and is an LED light source as a line light source for reading one line of data, and 102 is a focusing rod. A lens array, 103 is a one-dimensional image sensor, 104 is a sensor drive circuit, 105 is an amplification circuit, 106 is an A / D conversion circuit, 107 is a frame memory, 108 is a binarization processing section, and 109 is a printer section. .. Further, 110 is a feature extraction unit, 111 is an address control unit of the frame memory, 11
2 is an LED light emission control unit. Hereinafter, the flow of signal processing in the embodiment will be described in detail in three stages with reference to FIG.

(First Step) When the card 100 is conveyed in the direction of the arrow 120 by the conveying means (not shown) and comes under the image sensor 103, the LED light emission control section 112.
Then, the embossed area of the card is illuminated by the illumination light of the LED light source 101 whose emission intensity is controlled in the reading line cycle of the image sensor.

The reflected light from the card illuminated by the LED light source is imaged on the image sensor 103 via the rod lens array 102. The reflected light formed into an image is photoelectrically converted by the image sensor under the control of the sensor drive circuit 104, and the converted weak read analog signal is amplified to a predetermined level by the amplifier circuit 105. The amplified read analog signal is transferred to the A / D conversion circuit 10 at the next stage.
6 is supplied. This A / D conversion circuit 106 converts the read analog signal into, for example, 8 bits per pixel (256 gradations).
After being converted into a digital signal representing the multi-valued density of, the signal is supplied to the next frame memory 107 and the feature extraction unit 110.

The frame memory 107 is an address controller 1
Under the control of 11, during the memory writing (during card reading), the image data for "white embossed reading" and the image data for "black embossed reading" are written in the frame memory line by line.

On the other hand, in the feature extraction unit 110, in order to extract the background color feature of the card used for reading, the image data for "white emboss reading" and the image data for "black emboss reading" are selected from the image data of one screen. The frequency of the density value is counted for each of the image data, and the frequency distribution of each is extracted.

(Second step) At the same time when the reading of the card is completed, the feature extraction unit 110 determines from the two types of frequency distributions extracted from the image data for "white embossed reading" and the image data for "black embossed reading", The characteristics of the card used, that is, whether the background color of the card surface is a white card or a black card is determined.

(Third Step) In the third step, reading from the frame memory 107, pseudo gradation processing in the binarization processing unit 108, and printing operation are performed. When reading the frame memory, if the used card is a white card in the feature extraction unit in the second step by the address control unit 111, the image data for "white embossed reading" is read from the frame memory, and black is read. If the card is determined to be a card, the image data for "black emboss reading" is read out and supplied to the binarization processing unit in the next stage.

The binarization processing unit 108 performs the binarization processing by the γ correction processing (not shown) and the pseudo gradation processing for gradation printing, such as dither processing and error diffusion processing. After that, the printer unit 109 prints out by a printer of, for example, a thermal recording system and uses this as an image image of a card.

Next, referring to FIG. 3, the LED light emission control unit 112
As a first embodiment, a method of changing the drive voltage of the LED light source in synchronization with the read line cycle of the image sensor will be described. For the LED light source 101,
LED driving circuit 114 to the driving voltage of the light source is set to V _w for "white embossing read", the LED drive circuit 115 is set to V _b for "black embossing read", and switches the driving circuit of the two drive circuits It is composed of the selection unit 113. With such a configuration, the drive circuit selection unit 1
Reference numeral 13 denotes a switching control signal from a sensor drive circuit (not shown), and selects whether the drive voltage to the LED light source 101 is supplied from the LED drive circuit 114 or the LED drive circuit 115. Therefore, the LED light emission control unit 112
For example, starting from the time when the conveyed card is directly below the image sensor, when the reading line of the image sensor is an odd line, the "white emboss reading" LED
The control is performed so that the drive circuit 114 is connected and the LED drive circuit 115 for "black emboss reading" is connected when the line is even. 3A shows a start signal of the image sensor, and FIG. 3B shows a switching control signal from the sensor drive circuit, which is "H" when the voltage level is "H" by the operation of the drive circuit selection unit. L for "white embossed reading"
The LED driving circuit for "black emboss reading" is connected to the LED light source at the voltage level "L" of the ED driving circuit. In addition, FIG. 3 (c) shows that the drive circuit selection section displays the LED
The state of the drive voltage supplied to the light source is shown, and the vertical axis shows the voltage value applied to the LED light source.

FIG. 4 shows a second embodiment of the LED light emission control section 112.
As a second embodiment, a method of changing the driving time of the LED light source in synchronization with the read line cycle of the image sensor will be described below. LED light source 1
01 is connected to the LED drive circuit 116, the LED light source 101 and the LED drive circuit 116, which can obtain the emission intensity that can be obtained in “black embossed reading” within the reading time of one line. Turn on / off the drive voltage to the LED light source by the LED blink control signal
It is composed of an LED control circuit 117 for controlling. In addition, the LED blinking control signal from the sensor drive circuit is the L required for “white emboss reading” using the LED drive circuit 116.
It is a control signal for lighting the LED light source 101 for the ED lighting time T _W and the LED lighting time T _b required for “black emboss reading”. As in the first embodiment, the control method of the LED light emission control unit sets the LED light emission time to T _W when the read line of the image sensor is an odd line, and sets the LED light source to the light emission time T _b when it is an even line. It is a method of emitting light.

FIG. 4A shows the start signal of the image sensor, and FIG. 4B shows the LED blinking control signal from the sensor drive circuit. When the voltage level is "H", the LED is turned on (ON), When the voltage level is "L", the light source goes out (OF
F) is meant. Further, FIG. 7C shows the state of the drive voltage supplied to the LED light source. It is needless to say that the read image data on the image sensor read by the LED light emission control unit 112 is the image data for "white embossed reading" on even lines and the image data for "black embossed reading" on odd lines. Yes.

FIG. 5 shows the level relation of the image data of the white card and the black card obtained from the LED light source whose light emission is controlled in the above-mentioned first embodiment, and FIG.
Is a start signal of the image sensor, (b) is an LED drive voltage corresponding to the light emission intensity of the LED light source, (c) is an analog signal input to the A / D conversion circuit with image data obtained from a white card, (d) Indicates the analog signal input to the A / D conversion circuit by the image data obtained from the black card. Also, V ⁺ and V ⁻ in the figure are A /
With the white reference voltage and the black reference voltage supplied to the D conversion circuit, A
The analog signal input to the / D conversion circuit is converted between V ⁺ and V ⁻ into a digital signal representing multi-valued density of, for example, 8 bits (256 gradations) for one pixel.

In FIG. 5, when the read line of the image sensor is an odd line, the light emission intensity of the LED light source shows a "white embossed read" state, and when it is an even line, it shows a "black embossed read" state, which is output from the image sensor. In the image data, the odd lines ((a) in the figure) are for "black emboss scanning" and the even lines ((a) in the figure)
Indicates that the image data is for “white emboss reading”.

Next, the feature extraction method will be described with reference to FIG. 6A shows an example of the frequency distribution obtained from a white card, and FIG. 6B shows an example of the frequency distribution obtained from a black card. In FIG. 6, the horizontal axis represents the brightness of the image data as a density value of 0 to 255 levels, and the vertical axis represents the number of occurrences. Figure 6
The frequency distributions shown in (A) and (B) are the frequency distributions obtained in the above-described embodiment, the solid line graphs are the frequency distributions of the odd line image data (“black emboss read” data), and the broken lines are Is a frequency distribution of image data of even lines (“white embossed read” data).

Focusing on the frequency distributions of both, in the white card, the frequency distribution of the image data of the odd line is concentrated near the maximum density value, and in the black card, the frequency distribution of the image data of the even line is the minimum density value. You can see that they are concentrated in the vicinity. This is too strong in the "black embossed reading" state when the emission intensity of the LED light source is a white card,
In the case of a black card, it means that the "white emboss read" status is too weak. In practice, it is determined whether the optimum image data is the odd line data or the even line data from the frequency distribution of the odd line and the even line obtained from various cards from the white card to the black card. As this determination method, there is a method of making a determination based on a density value indicating the maximum number of occurrences of each obtained from two types of frequency distributions, or a method of making a determination from a concentration range in which the number of occurrences is a predetermined number or more.

In the above-mentioned embodiment, the characteristic of the card is judged by the frequency distribution of the read image data. However, the multi-value of each of the "white embossed read" image data and the "black embossed read" image data is obtained. There is also a method of determining the background color of the card from the cumulative addition value of data.

[0030]

As described above in detail, according to the card image reading apparatus of the present invention, even when various kinds of design cards, especially black cards are used, the reading in the optical system in the first stage is performed. The light emission intensity of the LED light source is prepared in advance for both "white emboss reading" and "black emboss reading", and the image data of each is recorded and used in the second stage feature extraction unit. The background color of the card is automatically determined, and the signal processing unit in the third stage selects the image data that is most suitable for the background color of the card, performs signal processing, and prints this out. It has an excellent effect that a clear image image can always be obtained even in various design cards, especially black cards.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a card image reading apparatus of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional card image reading apparatus.

FIG. 3 is an explanatory diagram of a first embodiment of an LED light emission control unit.

FIG. 4 is an explanatory diagram of a second embodiment of an LED light emission control unit.

FIG. 5 is a diagram showing a level relationship between LED emission intensity and image data.

FIG. 6 is a frequency distribution chart of a white card and a black card.

[Explanation of symbols]

 100 Cashing Card 101 LED Light Source 102 Focusing Rod Lens Array 103 One-dimensional Image Sensor 104 Sensor Driving Circuit 105 Amplifying Circuit 106 A / D Conversion Circuit 107 Frame Memory 108 Binarization Processing Unit 109 Printer Unit 110 Feature Extraction Unit 111 Address control unit 112 LED emission control unit 120 Card conveyance direction

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication H04N 1/04 103 Z 7251-5C 1/40 101 B 9068-5C

Claims (2)

[Claims] 1. A reading medium, such as a cashing card, having an optical system including a line light source and an image sensor, a signal processing system including an amplifier circuit, an A / D conversion circuit, etc. In an image reading device for a card that reads an image image, the emission intensity of a line light source in the optical system is synchronized with the reading line cycle of an image sensor to obtain an emission intensity based on a white card and an emission intensity based on a black card. A means for switching and emitting light; a means for storing image data representing two kinds of multi-valued densities obtained from the two kinds of light emission intensities; a feature for extracting a background color feature of the card from the two kinds of image data Extracting means and the above-mentioned 2 based on the feature extraction result by the feature extracting means
An image reading device for a card, characterized in that one of image data of a type is selected. 2. The card image reading device according to claim 1, wherein the feature extracting means extracts the frequency distribution of each density value by counting the frequency of the density values from the two types of image data. Image reading device for cards.