JPH1049654A - Signal correcting method for image fetching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform seure discrimination at all times even if the reflected light quantity characteristic value of the surface of an object to be read varies, by making corrections for varying the amplification factor of an image signal sampled by an area sensor according to the quantity of reflected light from a reflected light quantity measuring instrument. SOLUTION: Prior to a read of an image of the read object 2 by the area sensor 3, the reflected light quantity ratio measuring arithmetic part 10 measures the quantity of totally reflected light from the read object 2, light by a light source 11 which is constant in light quantity, by a photosensor 12, and a reflected light quantity ratio MR calculated by the arithmetic part 10 is inputted to a control circuit 8. When the reflected light quantity ratio MR is larger than a certain value, the read object 2 is whitish and corrections are made by using a characteristics curve suppressing a high level. When the reflected light quantity ratio MR is within a mean range, no correction is made. When the reflected light quantity ratio MR is smaller than the certain value, the read object 2 is blackish and corrections are made by using a characteristic curve increasing a low-level output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recognizing the surface pattern and color of an object to be read, such as coins, medals, cards, bills, etc., cans, bottles, etc. The present invention relates to a signal correction method for reliably recognizing an object to be read having a difference or a ratio of a reflected light amount ratio (reflectance) of light, an irregularly reflected light amount and a total reflected light amount.

[0002]

2. Description of the Related Art The necessity of discriminating the authenticity and type of a given article is increasing, but this tendency is particularly remarkable in the field of bank machines and vending machines handling coins and medals.
Conventional coin readers determine the authenticity of a coin based on the external dimensions (diameter, thickness) and material of the coin.
This discrimination method appears to be incapable of sufficiently addressing social issues associated with recent internationalization. That is, although many foreigners have entered Japan due to recent internationalization, a large number of foreign coins very similar to Japanese coins have flowed in and flooded with this entry, and as a result, foreign countries that are difficult to distinguish It is not uncommon for coins to be exercised to severely hinder economic activities. For example, the 500-yen coin issued by the Japanese government is the largest size in the world, and from the external dimensions such as the size and thickness of the coin,
It can hardly be distinguished from foreign coins such as Korea and Russia. Therefore, recent coin readers use an illuminating device to determine the denomination and authenticity of the coin on the basis of the stamp of the coin, in other words, the figures, numbers, or characters on the exposed surface of the coin. Have been.

A conventional coin reader is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-89276. This coin reader is an image pickup device in which a surface pattern of a conveyed coin is disposed above a conveying path. The coin is photographed, and the authenticity of the coin is determined from the photographed image data.

[0004]

However, in the conventional coin reading apparatus, the image information (which reflects the color information of a stable level correctly) by the difference in the reflected light amount ratio due to the difference in coin surface color due to the denomination and aging. It is difficult to take in luminance information), and there is a problem in discriminating continuous coins of a plurality of denominations. That is, the light source is adjusted so as to keep the light emission intensity constant, and an image reflected from the coin is captured by an image sensor or the like, but since the captured image is surface reflected light of the coin, Even if the light source intensity is controlled to a constant value, the image becomes dark if the reflected light amount ratio is reduced due to surface contamination or oxidation, and if it becomes dark, color information cannot be obtained correctly. Alternatively, before capturing an image, a coin is irradiated with light in advance to measure the ratio of the amount of reflected light on the surface of the coin, and the image reflected from the coin is captured after adjusting the amount of light emission so that the intensity of the reflected light is constant. In addition, since the exposure amount is always constant, the surface pattern can be stably detected, but there is a slight difference in color information. For this reason, it is conceivable to increase the irradiation light amount when the reflected light amount ratio or the scattered light ratio decreases due to surface contamination of the coin or metal oxidation of the surface, but the irradiation amount was increased uniformly. In such a case, there is a problem that the color information cannot be read accurately, and there is a demand for the emergence of a method capable of stably performing coin identification by a correction method that makes the contrast between a new coin and a circulating coin constant. I have. The present invention has been made in view of the above circumstances, and an object of the present invention is to ensure that an object to be read such as a coin is read in an imaging area of an image sensor, and to capture an image of the object to be read. Provided is a signal correction method for an image capturing device that measures and calculates a reflected light amount characteristic value of an object to be read in advance and changes an amplification factor of an image signal according to the measured and calculated reflected light amount characteristic value. It is in. That is, an object of the present invention is to predict the contrast from the characteristic value obtained by measuring the total reflection light and the scattered reflection light, and to change the amplification characteristics to a coin having a large diffuse reflection due to a damage state of the coin surface and a low contrast coin. It is to provide a signal correction method.

[0005]

According to the present invention, there is provided a reflected light amount measuring / calculating section for measuring and calculating the amount of light reflected by illuminating a conveyed object to be read, and controlling the amount of light applied to the object to be read. The present invention relates to a signal correction method in a device for capturing an image of a conveyed reading object, comprising: a light emission amount control unit that performs the operation; and an area sensor that collects a two-dimensional image of the reading object irradiated by the light emission amount control unit. The above object of the present invention is achieved by performing a correction for changing an amplification factor of an image signal collected by the area sensor in accordance with a reflected light amount from the reflected light amount calculation unit. The correction can be more effectively achieved by applying a high amplification factor when the amount of reflected light is low, and by applying a low amplification factor when the amount of reflected light is high. The correction can be achieved by changing a reference voltage when converting an analog output signal of the area sensor into a digital signal.

Further, a reflected light amount measuring / calculating section for measuring and calculating the amount of light reflected by illuminating the conveyed object to be read, light emission amount control means for controlling the amount of light applied to the object to be read, and And an area sensor for collecting a two-dimensional image of the object to be read illuminated by the light emission amount control means, wherein the area is determined in accordance with the calculation result of the reflected light amount measurement calculation unit. The present invention is also applicable to a case where a correction for changing an amplification factor is performed so that an amplification output of an analog output signal of the area sensor according to a magnitude of an image signal collected by a sensor decreases nonlinearly. The goal is achieved. Further, the correction for changing the amplification factor may depend on a terminal voltage for changing the γ characteristic of the area sensor, or may be performed by a gain switching means of a nonlinear element built in the video amplifier. An A / D converter for A / D-converting an analog output signal of an image signal obtained by the area sensor in the image capturing device for conveying and reading an object;
The output of the A / D converter is connected to lower bits of an address portion, a correction value is written in a memory area indicated by the address, and a plurality of different areas are selected by an upper bit of the address portion. When performing the A / D conversion with the ROM storing the correction values of the types,
Based on the calculation result of the reflected light amount measurement calculation unit, the RO
The object can also be achieved by setting an upper address signal of M and inputting the output of the A / D converter to the ROM to output the corrected data from the data section of the ROM. The characteristic value of the amount of reflected light is the ratio of the amount of reflected light to the total reflected light, or the difference or ratio between the totally reflected light and the irregularly reflected light.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When an image of the surface of an object to be read, such as a coin, is captured by an image sensor such as a CCD and pattern recognition is performed, the surface of the object to be read is kept in an environment where the light source and the amount of received light are always constant. Even if an image is captured, the image is not always read in the correct color tone. Therefore, without being affected by the surface color that changes due to the type or aging of the surface of the object to be read, the first one with a lack of contrast so that the surface pattern can be read with an appropriate exposure amount at all times,
That is, for a reading object having a low reflected light amount characteristic value such as a reflected light amount ratio, the contrast is adjusted so as to be a constant value which is a standard value. This is achieved by using a non-linear amplifier (for example, an amplifier having a γ characteristic). Signal processing for changing the gain in accordance with the characteristic value of the amount of reflected light of the object to be read is performed using the contrast correction means. The expression of γ here is not a numerical value to be specified as in γ correction used in a television, but a large gain is set for a reading target having a small reflected light amount characteristic value, and a large gain is set for a reading target having a large reflected light amount characteristic value. Is a γ function for giving a non-linear amplification characteristic such as reducing the gain, and reads out image data by changing the gain according to the reflected light amount characteristic value monitored before imaging of the object to be read.

FIG. 1 shows a surface pattern reflected from a reading object 2 conveyed on a conveying path 1 optically read by an area sensor 3 composed of a CCD image sensor or the like, and the video signal VS is processed by video signal processing. After being processed by the circuit 4, it is amplified by the video amplifier 5, the amplified video signal VSB is converted into a digital value DV by the A / D converter 6, and the data stored in the ROM 7 is read out as necessary. 1 shows a general image capturing device which is processed by a control circuit 8 composed of the above. In such an image capturing device, the parameters of each device are fixed, and the image is always captured with the same parameters even if the luminance (reflection light amount characteristic value such as a reflection light amount ratio) of the surface of the reading target 2 changes. Since the processing is performed, accurate image information cannot be captured when the surface luminance of the reading target object 2 changes. The ROM 7 has A /
The table data is output in accordance with the digital value DV from the D converter 6, and is not always necessary.

Therefore, according to the present invention, as shown in FIG.
Prior to the image reading of the object 2 to be read by the area sensor 3, the reflected light amount ratio
The amount of totally reflected light from the object 2 to be read is measured by the photo sensor 12 and the reflected light amount ratio MR calculated and calculated by the reflected light ratio measurement calculation unit 10 is input to the control circuit 8. The relationship between the luminance of the reading target 2 and the reflected light amount ratio MR is, for example, as shown in FIG. 3A. The bright (white) reading target 2 has a large reflected light ratio MR and is dark (dark). The reading target 2 has a small reflected light amount ratio MR. Then, the control circuit 8 controls the circuit system so that the imaging output (average value) becomes a constant value regardless of the magnitude of the reflected light amount ratio MR. That is, in the case of the area AR1 in FIG. 3A where the reflection light amount ratio MR is larger than a certain value, the reading target 2 is entirely whitish, and the high-level output may be so-called “flying (white clip)”. The correction is performed using a characteristic curve that suppresses the high level as shown in FIG. When the reflected light amount ratio MR is in the average range AR2, the object 2 is an object to be read having an average luminance.
No particular correction is made as shown in FIG. That is, linear processing is performed. In the case of the area AR3 in FIG. 3A where the reflected light amount ratio MR is smaller than a certain value, the reading target object 2 is entirely dark, and the low-level output may be so-called “crushed”. The correction is made by using a characteristic curve that increases the low-level output as shown in FIG.

When the control circuit 8 performs signal correction as shown in FIG. 3, a method of changing the γ coefficient by giving a γ correction signal γC to the video signal processing circuit 4 as shown in FIG.
A method of giving a gain correction signal GC to the video amplifier 5 to vary the gain, the reference voltage V of the A / D converter 6
_ref is varied by a reference voltage command RFV, A
A method of performing level conversion based on a table selection signal TS by inserting a ROM 7 that outputs table data in accordance with a digital value DV from a / D converter 6, and the control circuit 8 itself performs the same correction as above using software. There is a method of performing correction and a method of performing correction by combining the above methods. The correction in the case of using the ROM 7 has an advantage that the conversion value can be freely changed from a linear value to a value using an extremely characteristic function according to the table value.

When the γ coefficient of the video signal processing circuit 4 is varied by the γ correction signal γC from the control circuit 8, when the reflected light amount ratio MR is large as shown in FIG. When the value is small, the γ coefficient is increased. FIG. 5 shows an example in which the signal is varied by a digital method. As shown in FIG. 6, a 2-bit γ correction signal γC (γ
1, γ2) to digitally vary the γ coefficient. FIG. 7 shows an example in which the digital γ correction signal γC from the control circuit 8 is changed in the analog system.
Is converted into an analog γ correction signal γi by the D / A converter 81 and input to the video signal processing circuit 4. The video signal processing circuit 4 can vary the γ coefficient corresponding to the reflected light amount ratio MR by varying the γ coefficient in the relationship shown in FIG.

FIG. 9 shows an example in which the gain G of the video amplifier 5 is varied by the gain correction signal GC from the control circuit 8. The relationship between the reflected light amount ratio MR and the gain G is as shown in FIG. 10, for example. When the reflected light amount ratio MR is large, the gain G is decreased, and when the reflected light amount ratio MR is small, the gain G is increased. Gain correction signal GC
Is processed in an analog manner by the video amplifier 5 and the control circuit 8
Since the gain correction signal GC output from is digital, in this case, it may be converted into an analog signal by a D / A converter. FIG. 11 shows the reference voltage V _ref of the A / D converter 6.
Is varied according to the reflection light amount ratio MR,
The control circuit 8 decreases the reference voltage command RFV when the reflected light amount ratio MR is small, and increases the reference voltage command RFV when the reflected light amount ratio MR is large. Since the reference voltage command RFV from the control circuit 8 is a digital value,
A / D converter 82 converts the analog value into an analog value and converts it into an analog value.
_Is the reference voltage V _ref . Therefore, the reflected light amount ratio MR
And the relationship between the reference voltage _{V ref} is as FIG. 12 (A), when the reference voltage _{V ref} is large, A / D conversion in relation to the low resolution shown in FIG. 12 (B), the reference voltage _{V ref}
Is small, A / D conversion is performed in a high-resolution relationship shown in FIG. That is, when the apparent amplification degree becomes large and the same signal is input, the readout A / D conversion value becomes larger when the reference voltage _Vref is smaller than when the reference voltage _Vref is large. As described above, according to the magnitude of the reflected light amount ratio MR, A
Since the reference voltage V _ref of the / D converter 6 is variable,
Sufficient conversion accuracy can be obtained even for the reading target 2 having a dull overall reflection amount ratio MR.

FIG. 13 shows an example in which the ROM 7 is interposed as a level conversion means at the subsequent stage of the A / D converter 6. The ROM 7 is controlled based on a table selection signal TS from the control circuit 8.
The data table stored in is read out and output. In this case, when the reflected light amount ratio MR is small, the level is enlarged and emphasized, and when the reflected light amount ratio MR is large, the level is held. In other words, connected to the lower bits of the address portion of the ROM7 the digital value _{DV (A 0 ~A n-1} ), previously write the correction value to a memory area indicated by the address, the upper bit address (A _n ~ A _{n + m} ) stores a plurality of different types of conversion data. FIG. 14A shows the input digital value DV.
The relationship between the conversion table No. and the digital value DVA as the video output is represented by the conversion table No. 0-No. k is shown in FIG.
4 (B) shows the relationship between the conversion table number, the number of conversion data, and the array. Conversion table No. 0-No. k
Stores ²ⁿ pieces of conversion data.

In the above description, the photosensor 12 measures the amount of the totally reflected light, obtains the reflected light amount ratio as the light amount characteristic value, and corrects the signal. However, as shown in FIG. A photosensor 13 for receiving diffusely reflected light from the surface may be provided, and the difference between the total reflected light amount and the diffusely reflected light amount may be calculated by the measurement calculation unit 14. Also, FIG.
An example is shown in which the ratio between the irregularly reflected light and the total reflected light is calculated by the measurement calculation unit 15.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 17 is a perspective structural view showing an example of a coin image reading apparatus 100 as an image reading apparatus to which the present invention can be applied. The surface pattern made of figures, patterns, numbers, characters, and the like stamped on the surface of the coin C is optically converted. This is a device that reads the information. The coin image reading device 100 includes a rectangular parallelepiped imaging unit 110, a flat plate 101 forming a transport path provided to face the upper surface of the imaging unit 110, and a pair of flat plates 101 disposed above the flat plate 101. Roller 102,1
02 and a conveyor belt comprising a conveyor belt 103 wound therearound. The height of the upper surface of the imaging unit 110 and the height of the upper surface of the flat plate 101 coincide with each other, and a single plane is formed as a whole to serve as a transport path for coins C. A gap substantially equal to the thickness of the coin C is provided between the conveying path surface and the lower surface of the conveying belt 103, and the coin C is conveyed through the gap by driving the belt conveyor.

As shown in detail in FIG. 18, the imaging unit 110 comprises a cubic case 111 having an open upper surface, and an upper plate 112 made of transparent glass which covers the upper surface opening of the case 111. At the center of the face plate 112,
A substantially circular reading window 1 surrounded by a light shielding member 114
In the housing 111, an area sensor 120 composed of a CCD image sensor is provided with an imaging lens 121.
And an infrared illuminating device 1 which is provided via an infrared transmitting filter 122 and comprises a number of infrared light emitting diodes arranged in a ring below the reading window 113.
A photosensor 1 such as a photodiode which is provided with a light source 30 and receives irradiation light from the surface of the coin C being conveyed
23 (for totally reflected light) and 124 (for diffusely reflected light) are provided. Further, a pair of light emitting diodes 104 and a photo sensor 105 are provided so as to be opposed to each other with the conveyance path interposed therebetween, so that light shielding is detected when the entire surface of the coin C enters the reading area. Further, in the housing 111,
A video circuit 140 and a timing circuit 150 are incorporated in the form of a printed circuit board or the like.
As shown in FIG. 7, coin transport guides 106A and 106B for transporting the coin C smoothly are provided. The infrared transmission filter 122 is provided so as to prevent unnecessary charge accumulation in the area sensor 120 due to extraneous leakage light and prevent image noise from occurring.

The circuit configuration is as shown in FIG. 20. The video circuit 140 has a video processing circuit 141 for inputting a read signal RS from the area sensor 120 and outputting a video signal VDS. Timing circuit 142 that regulates the timing of capturing an image by driving the driver, and driver 1 that drives area sensor 120
43. The timing circuit 150 determines a capture timing T1 for capturing an image and the infrared illuminating device 13 based on a light-blocking detection signal BL from the photosensor 105.
A timing signal generation circuit 151 for outputting a lighting timing T2 for lighting the illumination of 0, a differential amplifier 152 for differentially inputting and amplifying the amplified outputs PD1 and PD2 of the photosensors 123 and 124, and a photosensor 123
Of the amplified output DP1 from the control circuit 160 to the reference value RF1
And a hold circuit 1 that holds an output of the comparator 153 and outputs a gain correction signal GC.
54 and the output DPD of the differential amplifier 152
The comparator 155 includes a comparator 155 that compares the output of the comparator 155 with a reference value RF2 from 0, and a hold circuit 156 that holds an output of the comparator 155 and outputs a γ value correction signal γC. The gain correction signal GC and the γ correction signal γC are input to a video processing circuit 141 in the video circuit 140 so as to change the gain and the γ coefficient. The infrared lighting device 130
A FET 131 as a switching element to be turned on and off by the turn-on timing T2, it is composed of a plurality of light-emitting diode 132 connected between the power supply + _{V c} and FET 131.

The video signal VDS from the video circuit 140 is input to a control circuit 160 such as a coin discriminating device and subjected to image processing. As shown in FIG. 21, the control circuit 160 includes a CPU 161 for performing overall control, ROM 162 storing programs and the like, RAM 163 serving as a work area for signal processing and correction, an A / D converter 164 for converting a video signal VDS into a digital amount and taking it in, and a driver 143
Or the reference value RF1 of the comparators 153 and 155
And a D / A converter 165 for setting RF2 and the like based on a command from the CPU 161.

In such a configuration, the operation is shown in FIG.
2 will be described with reference to the time chart.

When the coin C is conveyed by the drive of the belt conveyor and reaches the position of the reading window 113, the light from the light emitting diode 104 is blocked at the end of the coin C, and the light is blocked as shown in FIG. Is detected by the photo sensor 105 (time t1). When light shielding is detected by the photo sensor 105, the timing signal generation circuit 151
The lighting timing T2 is output as shown in FIG.
By turning on 31, the infrared illuminating device 130
Is turned on until the time t1 ′.
The photo sensors 123 and 124 receive reflected light from the surface of the coin C by turning on the light emitting diode 132,
The photosensor 123 receives a part of the total reflection light and the irregular reflection light on the coin surface, and the photosensor 124 receives a part of the reflection light on the edge of the inscription on the coin surface and the irregular reflection light on the plane. Outputs PD1 and P of photosensors 123 and 124
D2 is input to the differential amplifier 152, and the differential amplifier 152
Is output to the comparator 155, and the output PD1 of the photosensor 123 is input to the comparator 153.
From the output level of the comparator 153, the luminance of the edge of the engraved mark of the read image is predicted. Further, the contrast of the read image is predicted from the output level of the comparator 155, and if it is determined that the contrast is smaller than the standard set value, the image processing circuit 14
The γ coefficient of 1 is switched to, for example, “1”, and when it is determined that it is larger than the standard set value, the γ coefficient is switched to “0.45”. 2 above
The two determinations and corrections are performed as shown in FIG. 22 (I), and are completed in a short time such that the conveyance of the coin C does not affect the reading (time t2).

When the monitoring and the correction are completed as described above, the timing signal generation circuit 151 outputs a capture timing T1 as shown in FIG. 22B (time t3), and the capture timing circuit 142 and the driver 143. , A reset pulse RSP is input to the area sensor 120, and the scanning position is set to the start position of the upper left corner. FIG. 22 (E)
As shown in (2), the area sensor 120 is in a state where the electric charge can be accumulated while the electric charge has been discarded to the overflow drain until then. Thereafter, during a predetermined blanking period, the coins C are lit by the lighting timing T2 for a time that allows a blur in a range in which the surface pattern of the coin C being transported can be sufficiently read (time t4 to t5). At the same time, the area sensor 120 converts the video charge accumulated during the period (t4 to t5) during which the infrared illuminator 130 is lit as shown in FIG. 22F as a video signal VDS as shown in FIG. Output (time t6). Light (infrared light) reflected at the edge of the mark of the coin C and incident on the imaging lens 121 passes through the infrared transmission filter 122 and is transmitted to the area sensor 120.
A line drawing image of the stamp of the coin C is formed thereon. The read signal RS of the coin C stored in each pixel of the area sensor 120 is input to the video processing circuit 141 as a time-series signal, and is obtained by a γ coefficient and a gain set before image capture as shown in FIG. The video signal VDS is input to the control circuit 160 and is subjected to image processing. FIG. 22C shows the vertical synchronization signal VD, and FIG. 22D shows the horizontal synchronization signal HD. In the NTSC standard, the vertical synchronization signal VD is 60.
Hz, and the horizontal synchronization signal HD in this case is 15.75.
KHz, and the clock CLK is 14.31818 MH
z.

As shown in FIG. 22 (I), the correction is performed from the time t1 when the infrared illuminator 130 is turned on. At this time, the control circuit 8 sets the gain correction signal GC in FIG. Performs an operation of writing a reference voltage command RFV to the D / A converter 82 for determining the reference voltage Vref. In the case of the circuit configuration of FIG. 13, the video signal VDS of FIG.
Each time the data is read by the LK, the output DV of the A / D converter 6 is read from the ROM 7
_D 0 by the input of the address _A 0 _{~A n-1} ~
And outputs the converted A / D conversion output DVA to D _n. As shown in FIG. 14, 1 is assigned to the address written in the table area.
The conversion value stored in one-to-one is written to the dual port RAM. Addresses _{An to An + m at} this time are shown in FIG.
2 according to the reflected light amount ratio at the time of the correction of 2.
Designated for M7.

The video processing circuit 141 varies the gain γ coefficient according to the gain correction signal GC and the γ correction signal γC. The circuit can be realized by a line function generating circuit. In the circuit of FIG. 23, by increasing the current i, the output voltage eo becomes a polygonal line function as shown in FIG. FIG. 24A shows an example of a basic circuit of a polygonal line function.
o has a slope of K / 3 from the reference voltage Vf as shown in FIG.
Is output as a linear function. By connecting and connecting such a basic circuit as shown in FIG. 25, a broken line function approximation circuit can be formed. In FIG. 25, the resistance ratios ko to k
The bias and the slope can be determined by setting n1 and the reference voltages Vr1 to Vrn. When the switch is connected to the switch a, the addition is performed, and when the switch is connected to the switch b, the subtraction is performed.

[0024]

As described in detail above, according to the present invention, since the conversion characteristic is varied based on the ratio of the amount of reflected light on the surface of the object to be read, it is possible to always maintain a contrast equal to or higher than a certain value. And an accurate surface pattern can be detected. In addition, after measuring the ratio of the amount of reflected light or the difference in the amount of reflected light between the total reflected light and the scattered light on the surface in advance, the conversion characteristics are varied to obtain surface pattern information that reflects the hue of the coin with an appropriate contrast. Thus, highly accurate identification and determination can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a circuit configuration example of a general image capturing device.

FIG. 2 is a block diagram illustrating a circuit configuration example of an image capturing apparatus to which the present invention has been applied.

FIG. 3 is a diagram for explaining the principle of the present invention.

FIG. 4 is a diagram for explaining the variation of the γ coefficient of the video signal processing circuit according to the present invention.

FIG. 5 is a block diagram illustrating an example of an apparatus that varies a γ coefficient by a digital method.

FIG. 6 is a diagram for explaining the operation of FIG. 5;

FIG. 7 is a block diagram illustrating an example of an apparatus that varies a γ coefficient in an analog manner.

FIG. 8 is a diagram for explaining the operation of FIG. 7;

FIG. 9 is a diagram showing an example of an apparatus for varying the gain of a video amplifier according to the present invention.

FIG. 10 is a diagram for explaining the operation of FIG. 9;

FIG. 11 is a block diagram illustrating an example of a device that varies a reference voltage of an A / D converter.

FIG. 12 is a diagram for explaining the operation of FIG. 11;

FIG. 13 is a block diagram showing an example of an apparatus for performing level conversion using a ROM.

FIG. 14 is a diagram for explaining the operation of FIG. 13;

FIG. 15 is a block diagram showing a second circuit configuration example of the image capturing device to which the present invention has been applied.

FIG. 16 is a block diagram showing a third example of the circuit configuration of the image capturing apparatus to which the present invention has been applied.

FIG. 17 is a perspective structural view showing an example of a coin image reading device according to the present invention.

FIG. 18 is a cross-sectional structure diagram illustrating a structure example of an imaging unit.

FIG. 19 is a plan view showing the structure of a transport path.

FIG. 20 is a connection diagram illustrating a circuit configuration example to which the present invention is applied.

FIG. 21 is a block diagram illustrating an example of a control circuit.

FIG. 22 is a time chart showing an operation example of the present invention.

FIG. 23 is a diagram showing the principle of a polygonal line function generating circuit applicable to the present invention.

FIG. 24 is a diagram showing a basic circuit for generating a polygonal line function.

FIG. 25 is a connection diagram illustrating an example of a polygonal function approximation circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveyance path 2 Object to be read 3 Area sensor 4 Video signal processing circuit 5 Video amplifier 6 A / D converter 7 ROM 8 Control circuit 10 Reflection light amount ratio measurement calculation unit 11 Light source 100 Coin image reader 103 Conveyor belt 110 Imaging unit 113 Reading window 114 Light blocking member 120 Area sensor 123, 124 Photosensor 130 Infrared illuminator 140 Video circuit 141 Video processing circuit 142 Capture timing circuit 143 Driver 150 Timing circuit 151 Timing signal generation circuit 152 Operational amplifier 153, 155 Comparator 154, 156 Hold circuit 160 Control circuit 161 CPU 162 ROM 163 RAM

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 1/40 101Z (72) Inventor Yumi Ishino 1-3-1 Shimoteno, Himeji-shi, Hyogo gross (72) Inventor Yasuo Ishiguro 2-16-20 Shimura, Itabashi-ku, Tokyo Copal Corporation (72) Inventor Naofumi Amano 2-16-20 Shimura, Itabashi-ku, Tokyo Copal Corporation Inside

Claims (8)

[Claims] A measuring section for measuring and calculating the amount of light reflected by irradiating the object to be read with light; a light emission amount controlling means for controlling the amount of light applied to the object to be read; And an area sensor for collecting a two-dimensional image of the object to be read irradiated by the light emission amount control means. A signal correction method for an image capture device, wherein a correction is performed to change an amplification factor of an image signal captured by an area sensor. 2. The image capturing apparatus according to claim 1, wherein the correction applies a high amplification factor when the amount of reflected light is low, and applies a low amplification factor when the amount of reflected light is high. Signal correction method. 3. The correction according to claim 2, wherein the correction is performed by changing a reference voltage when converting an analog output signal of the area sensor into a digital signal.
3. The signal correction method for an image capturing device according to item 1. 4. The signal correction method for an image capturing device according to claim 1, wherein the amount of reflected light is a ratio of the amount of reflected light to total reflected light, or a difference or a ratio between total reflected light and irregularly reflected light. 5. A reflected light amount specifying and calculating unit for measuring and calculating the amount of light reflected by irradiating the read object to be conveyed, an emission amount control unit for controlling the amount of light applied to the read object, And an area sensor for collecting a two-dimensional image of the object to be read illuminated by the light emission amount control means, wherein the area is determined in accordance with the calculation result of the reflected light amount measurement calculation unit. A correction is made to change the amplification factor so that the amplified output of the analog output signal of the area sensor according to the magnitude of the image signal taken by the sensor decreases nonlinearly. Signal correction method for image capture device. 6. The method according to claim 5, wherein the correction for changing the amplification factor depends on a terminal voltage for changing a γ characteristic of the area sensor. 7. The signal correction method for an image reading device according to claim 4, wherein the correction for changing the amplification factor is performed by a gain switching means of a non-linear element built in the video amplifier. 8. A reflected light amount measurement / calculation unit for measuring and calculating the amount of light reflected by irradiating the conveyed reading object, light emission amount control means for controlling the amount of light applied to the reading object, and And an area sensor for collecting a two-dimensional image of the object to be read irradiated by the light emission amount control means, wherein an analog output signal of the image signal collected by the area sensor is output. An A / D converter for A / D conversion and an output of the A / D converter are connected to lower bits of an address portion, and a correction value is written in a memory area indicated by the address. A ROM in which a plurality of different correction values are stored in an area selected by the upper bit, and a ROM based on the calculation result of the reflected light amount measurement calculation unit when performing the A / D conversion. And setting an upper address signal of the ROM and inputting an output of the A / D converter to the ROM so that corrected data is output from a data portion of the ROM. Signal correction method for embedded devices.