JP2000222614A - Image reading sensor adjustment method and device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an image reading sensor capable of acquiring an image that is stable against a change over time. SOLUTION: The light emission for each block adjusted so that the image output becomes uniform in a state where a reference medium having a uniform transmittance is placed between a light emitting unit 1 and a light receiving unit 2 whose lighting is controlled for each of a plurality of blocks. The amount setting value is stored in the light emission amount setting storage unit 7, the exposure time and the lighting time when the image output is not saturated in the absence of the reference medium are stored in the adjustment condition storage unit 8, and the image output and the block when all the lights are turned on under the adjustment condition. The peak position and the peak value of the image output at the time of lighting each time are stored in the initial value storage unit 9. At the time of adjustment, the set value adjustment processing unit 6 adjusts the light emission amount set value for each block so that the output value at the peak position matches the initial peak value or the output difference near the peak position is minimized. The amount is stored in the set value storage unit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting an image reading sensor, and more particularly, to a bill discriminating apparatus for determining the authenticity of a bill. The present invention relates to a method and an apparatus for adjusting an image reading sensor capable of maintaining a state at the time of shipment even if received.

[0002]

2. Description of the Related Art A bill discriminating apparatus reads a printed image of an inserted bill and discriminates the authenticity and denomination of the bill based on the image information. Here, the part which reads the image of a bill is an image reading sensor, and usually a line sensor is used. When taking a full image of a banknote, a line sensor is arranged in a direction perpendicular to the direction in which the banknote is transported, and the line sensor receives reflected light or transmitted light of the illuminated banknote, thereby obtaining a one-dimensional image of the banknote. Is read, and the reading of the one-dimensional image is repeatedly performed in the transport direction of the bill, whereby a two-dimensional image of the bill can be obtained. An example of the configuration of such an image reading sensor is described below.

FIG. 11 is a diagram showing an example of the configuration of an image reading sensor of a bill validator. The illustrated image reading sensor is a lens reduction transmission type sensor, and has a light source unit 21, a light receiving unit 22, and a control unit as main components. The light source unit 21 includes a plurality of light emitting diodes (L
ED) are arranged in an array, and the light receiving unit 22 is a linear solid-state imaging device that receives a transmitted light from the bill 23 and converts an optical signal into an electric signal, for example, a charge-coupled device. It comprises an element (CCD) 24 and a lens 25 for forming a bill image on the CCD 24. The control unit controls the CCD 2 in the light receiving unit 22.
4, a CCD driving circuit 26 for controlling the reading of
An amplification circuit 27 for amplifying the signal read from
An analog converter that converts the amplified signal to a digital signal
A digital converter (A / D converter) 28 and a control circuit 2 for correcting the read image and outputting it as a banknote image and controlling the light emission amount of the LED in the light source unit 21
9, a digital / analog converter (D / A converter) 30 for converting a control signal of the light emission amount into an analog signal,
And a D drive circuit 31. The bill 23 is
It is assumed that the light passes through a transport path 32 between the light source unit 21 and the lens 25 in a direction perpendicular to the plane of the drawing.

The LED array of the light source unit 21 is divided into a plurality of adjacent LEDs as one block, and is set by the D / A converter 30 by the LED drive circuit 31 for each of the blocks B1 to Bn. Each is driven by an LED drive current.

Here, the current values of the LED blocks B1 to Bn are adjusted at the time of shipment so that the output values of the pixels of the CCD 24 become uniform, as follows. First, banknote 23
A reference medium having a uniform transmittance is placed over the entire surface of the transport path 32 of the image reading sensor through which the image reading sensor passes. The CCD output from the reference medium is closest to the preset reference value R, that is, the shading (non-uniformity of the output level of each pixel of the CCD 24 when uniform density is imaged) is the most flat. Thus, the set value of the D / A converter 30 is adjusted, and the drive current of each of the LED blocks B1 to Bn is determined. And each LED block B at this time
The set values of the D / A converter 30 of 1 to Bn are the shading correction coefficients P used for correction of each pixel of the CCD 24.
i is stored in the memory in the control circuit 29 together with i. This shading correction coefficient Pi is represented by the following equation.

[0006]

## EQU1 ## where Pi = R / Sri (1) where R is a reference value, Sr is a CCD output when a reference medium is inserted, and i is a reference code indicating the i-th pixel of the CCD.

[0007] In the bill validator in which the driving currents of the LED blocks B1 to Bn are adjusted at the time of shipment as described above, and the shading correction coefficient Pi is obtained and stored, when a bill image is read for bill validation. ,
Each of the LED blocks B1 to Bn is turned on with the drive current value at the time of shipment, and a raw image of the bill 23 is acquired by the CCD 24. Then, the obtained raw image data is subjected to a shading correction coefficient P
i is multiplied and sent to a discrimination processing unit (not shown) as a banknote image, where it is discriminated.

In this discrimination processing section, in order to cope with a temporal change of the image reading sensor, that is, a change in the temperature characteristics of the LED and the CCD and a change in the CCD output due to the deterioration of the LED, the CC which has been subjected to the shading correction processing of the bill image is processed.
The CCD output is standardized by the maximum value or the average value of the D output, and discrimination is performed using the standardized CCD output.

[0009]

However, in this conventional image reading sensor, the temperature characteristics and the degree of deterioration of the LEDs are the same for each LED, and therefore, the level of the CCD output fluctuates uniformly as a whole. Since it is assumed that correction is possible, there are the following problems. That is, although it is considered that there is almost no problem of deterioration of the CCD of the image reading sensor, the temperature characteristic and the degree of deterioration of the LED are often different for each LED. The degree will be different. Therefore, even if the CCD output fluctuation is corrected by the discrimination processing unit, it is difficult to perform correct correction. As a result, the discrimination processing unit cannot perform normal discrimination, and in the worst case, erroneous discrimination may occur. become.

[0010] The present invention has been made in view of the above points, and even if there is a difference in temperature characteristics of an image reading sensor and a change with time, an image output that is not affected by such a change. It is an object of the present invention to provide a method for adjusting an image reading sensor capable of obtaining the following.

[0011]

According to the present invention, in order to solve the above-mentioned problem, an image reading sensor for reading an image on a medium by detecting transmitted light of the medium illuminated by a light source which is controlled to be turned on for each block is adjusted. In the method, an exposure time and a lighting time at which an image output when light emitted by each block is directly received are not saturated, and a peak position and a peak value of the image output obtained at the exposure time and the lighting time are set to initial values in advance. When adjusting for changes over time, each block is sequentially lit with the exposure time and the lighting time, and the light emission amount of the block is set so that the output value at the peak position matches the peak value for each block. The method for adjusting the image reading sensor is characterized in that the image reading sensor is adjusted.

According to such an image reading sensor adjustment method, the peak position and the peak value when the light source is individually turned on for each block are remembered, and the peak when the individual light is turned on for each block is adjusted at the time of adjusting for the change over time. The light emission amount of each block is adjusted so that the output value at the position matches the peak value. With this, even if the peak value of a certain block changes due to aging,
Since the peak value is adjusted to be the initial peak value, the same image output as in the initial state can be always obtained.

According to the present invention, in an adjusting method of an image reading sensor for detecting a transmitted light of a medium illuminated by a light source controlled to be turned on for each block and reading an image on the medium, the light turned on for each block is provided. Exposure time and lighting time when the image output when light is directly received is not saturated,
The peak position of the image output obtained at the exposure time and the lighting time, and the initial image output obtained when all the blocks are turned on at the same time are obtained as initial values in advance, and each block is adjusted at the time of adjustment with time. An image output is obtained by simultaneously lighting all blocks at the exposure time and the lighting time, and the output value of the initial image output and the output value of the obtained image output in a predetermined pixel range including the peak position of each block. The sum of the output differences and the sum of the squares of the output differences are calculated, and the direction of increase or decrease in the amount of light emission is determined for each block according to the sign of the sum of the output differences, so that each block has the smallest sum of the squares of the output differences. And a method for adjusting the image reading sensor, wherein the amount of emitted light is adjusted.

According to this method of adjusting the image reading sensor,
Remember the peak position when the light source is individually turned on for each block and the output value when the light source is fully lit, and adjust each block so that the output difference near the peak position when the light source is fully lit is minimized when adjusting for aging. The amount of light emission was adjusted. With this, even if the peak position of a certain block changes due to aging, the output near the peak position is adjusted to be the output value near the initial peak position, so that the same image output as the initial state is always obtained. Obtainable.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where the present invention is applied to a bill image reading section of a bill discriminating apparatus.

FIG. 1 is a diagram showing a configuration example of a bill image reading section to which the present invention is applied. This bill image reading unit is an LED
Light emitting unit 1 composed of an array and light receiving unit 2 composed of a CCD
, An LED drive unit 3, a waveform acquisition unit 4, and a temporal change adjustment unit 5. The temporal change adjusting unit 5 includes a setting value adjusting processing unit 6, a light emission amount setting value storing unit 7, an adjustment condition storing unit 8, an initial value storing unit 9, and a lighting processing unit 10. Here, the specific configuration of the light emitting unit 1 and the light receiving unit 2 is the same as that shown in FIG. 11, and therefore, although not shown, a bill passes between the light emitting unit 1 and the light receiving unit 2. And a lens for forming a bill image on the CCD. The LED drive unit 3 is configured to control the lighting of the LED array of the light emitting unit 1 in a block manner. The waveform acquisition unit 4 includes the amplifier and the analog-digital converter shown in FIG. Includes the digital-to-analog converter of FIG.

This bill image reading unit is provided for each block of the LED array of the light emitting unit 1 which is adjusted at the time of shipment of the bill discriminating device so as to make the CCD output uniform by using a reference medium having a uniform transmittance. The set value of the digital / analog converter (hereinafter, referred to as D / A set value) is stored in the light emission amount set value storage unit 7.
The data at the time of adjustment when there is no reference medium is stored in the adjustment condition storage unit 8 and the initial value storage unit 9. Specifically, the adjustment condition storage unit 8 includes a CCD
CC when the light emitting unit is controlled and driven so that the output does not saturate
The D exposure time and the LED lighting time are stored, and the initial value storage unit 9 stores the peak position (CCD pixel number) of each LED block at that time, the peak value, and the waveform when all the LED blocks are simultaneously turned on. It is memorized.

Here, a first adjustment method for the change over time by the change over time adjusting section 5 will be described. When the bill discriminating device detects the entry of a bill, in the bill image reading unit, first, before reading the bill image, the aging change adjusting unit 5 first adjusts the temperature characteristic change of the LED of the light emitting unit 1 and the aging change. . That is, the lighting processing unit 10 controls the D / D for each LED block stored in the light emission amount setting value storage unit.
With the set value A, the light emitting unit 1 is sequentially turned on for each LED block under the same light emitting condition as the CCD exposure time and the LED lighting time stored in the adjustment condition storing unit 8, and the CCD output waveform received by the light receiving unit 2 at that time is obtained. It is received by the set value adjustment processing unit 6 via the waveform acquisition unit 4. The set value adjustment processing unit 6 compares the peak value of the individual waveform for each block with the peak value stored in the initial value storage unit 9. If they do not match, the D / A set value is increased or decreased. 10 drives the light-emitting unit 1 again with the set value. The operation of driving the light emitting unit 1 and comparing the peak value of the individual waveform at that time with the peak value stored in the initial value storage unit 9 is repeated until the peak values match. The set value is the D / A set value of the LED block of the light emitting unit 1 when the bill image is actually read. Perform this operation for all LE
This is performed for the D block. Thereby, the LE of the light emitting unit 1
The peak value of the individual waveform obtained when light is emitted for each D block is adjusted, and the overall light emission amount in the light emitting unit 1 is adjusted. Then, the raw image data of the banknote read by the waveform acquisition unit 4 after the temporal change adjustment is performed is sent to a shading correction processing unit (not shown), where a multiplication process is performed by a shading correction coefficient for each pixel. Will be.

Next, a description will be given of a second adjustment method for a change over time by the change over time adjustment section 5. When the bill validator detects the entry of a bill, the bill image reading unit performs
Prior to reading the banknote image, first, the temporal change adjusting unit 5 adjusts the temperature characteristic change of the LED of the light emitting unit 1 and the temporal change. That is, the lighting processing unit 10 emits light under the same light emission condition as the CCD exposure time and the LED lighting time stored in the adjustment condition storage unit 8 with the D / A set value for each LED block stored in the light emission amount set value storage unit. All L of part 1
The ED block is turned on at the same time. The CCD output waveform received by the light receiving unit 2 at that time is received by the set value adjustment processing unit 6 via the waveform acquisition unit 4, and the set value adjustment processing unit 6
Waveform near each peak position for each block and initial value storage unit 9
And the sum of squares of the output difference near the peak position is calculated. If the area is zero, the adjustment of the LED block is completed and the D / A set value is stored. If the area is not zero, the direction of increase / decrease of the D / A set value is determined, the D / A set value is increased / decreased, all lighting waveforms are reacquired, and the sum of squares of the output difference of the unadjusted LED block is calculated. I do. Here, the sum of squares of the output difference is compared with the previous sum of squares.
It is determined that the increase / decrease of the / A set value is excessive, and the previous D /
The A set value is recorded, and the adjustment of the block is completed. If there is no block larger than the previous sum of squares, the D / A set value is further increased or decreased, and all lighting waveforms are obtained again. This operation of increasing / decreasing the D / A set value and reacquiring all the lighting waveforms is repeated until there is no block in which the sum of squares of the output difference is smaller than the last time. When all the blocks have been adjusted, the adjustment ends. . Then, the raw image data of the banknote read by the waveform acquisition unit 4 after the temporal change adjustment is performed is sent to a shading correction processing unit (not shown), where a multiplication process is performed by a shading correction coefficient for each pixel. Will be.

Next, the details of these adjustment methods will be described. First, the concept of the first adjustment method will be described. FIG. 2 is an explanatory diagram showing a first adjustment method of the change with time of the CCD output. In this figure, the vertical axis indicates the CCD output, and the horizontal axis indicates the pixel position of the CCD. The entire lighting waveform Si at the time of shipment (initial) when all the LED blocks are lit, and LE
Initial individual waveform Ki at the time of shipment (initial) when the D blocks are individually lit, and temporal individual waveform Kki at the time of temporal adjustment
Are shown. Regarding the individual waveforms, here, the first block, the j-th block, and the n-th block are typically shown.

In the individual lighting waveform, in the first block, a bold solid line shows an initial individual waveform Ki1 at the time of shipment,
At the position X1, there is a peak of the CCD output, the peak value of which is A1.
And the peak value is Ak1. Similarly, in the j-th block, the initial individual waveform Ki at the time of shipment is indicated by a thick solid line.
j, there is a peak of the CCD output at position Xj, the peak value of which is Aj, and the broken line shows the temporal individual waveform Kkij at the time of temporal adjustment, the peak value of which is Akj, and further, in the n-th block, The bold solid line indicates the initial individual waveform Kin at the time of shipment, and the peak of the CCD output is at the position Xn, the peak value is An, and the broken line indicates the temporal individual waveform Kkin at the time of temporal adjustment, and the peak value is Akn. is there.

As described above, when the LED blocks are individually lit, if the peak value of each block has changed from the initial value due to aging, the peak value Ak becomes the initial peak value A. Thus, the drive current of the LED block, that is, the set value of the D / A converter may be adjusted.
Details of the adjustment method will be described below separately for the time of shipment and the time of adjustment.

FIG. 3 is a flowchart showing the flow of the factory adjustment process relating to the first adjustment method. At the time of shipment adjustment, first, a reference medium having a uniform transmittance that simulates a banknote is inserted into the transport path, and each of the LED blocks B1 to Bn is inserted.
, The drive current of each of the LED blocks B1 to Bn is adjusted so that the shading becomes the flattest, and the LED blocks B1 to Bn at that time are adjusted.
n D / A converter setting value Ij (LED block number j
= 1 to n) (step S1). Next, the reference medium is removed from the transport path, and the set value Ij in step S1 is set.
To turn on all the LED blocks at the same time, and obtain the entire lighting waveform Si (i: CCD pixel number) at that time. The CCD exposure time Tc and the LED lighting time Tl are reduced so that the maximum value Smax of all the lighting waveforms falls within the dynamic range (allowable input range) of the A / D converter. The time Tcs and the LED lighting time Tls are stored (step S2). Then, the D / A set value Ij in step S1 and the CCD in step S2
With the exposure time Tcs and the LED lighting time Tls, the individual waveform Kij (i = CCD pixel number, j = L) of each LED block
The ED block number) is acquired, and the peak position (CCD pixel number) Xj (j = LED block number) of each individual waveform and its peak value Aj (j = LED block number) are stored (step S3).

FIG. 4 is a flow chart showing the flow of the temporal adjustment process relating to the first adjustment method. The time adjustment process performed after shipment is started based on a bill entry detection or discrimination start signal. First, each LED block is individually lit, and an individual waveform Kkij at that time is obtained (step S11). Here, the D / A set value is stored in step S1 in FIG. 3 in order to individually light the LED blocks under the same conditions as those at the time of the previous aging adjustment at the time of shipment or when the aging adjustment has already been performed. Value Ij or the previous aging adjustment value I if aging adjustment has already been performed.
kj, CCD exposure time and LED lighting time are shown in FIG.
The individual waveform Kkij is obtained by turning on the CCD exposure time Tcs and LED lighting time Tls stored in step S2. Next, the output value Ak at the time of the temporal adjustment at the peak position Xj stored in step S3 of FIG.
j and an initial value Aj (the peak value stored in step S3 in FIG. 3), and it is determined whether or not they match (step S12).

Here, if they do not match, that is, if there is a change with time, the D / A set value is increased or decreased, and the individual waveform Kkij is reacquired (step S13), and the process returns to step S12 and again. The output value Akj is compared with the initial value Aj. If they match, the adjustment of the temporal change of the block has been completed, and the D / A set value at that time is stored (step S14). Next, it is determined whether or not the above-described adjustment processing has been performed for all blocks. If the adjustment of all blocks has been completed, this processing ends there. If any unprocessed blocks remain, the process proceeds to step S11. Return and move on to the next block adjustment.

Next, a second adjustment method will be described.
FIG. 5 is an explanatory diagram showing a second adjustment method of the change with time of the CCD output. In this figure, as in the case shown in FIG. 2, the entire lighting waveform Si at the time of shipment (initial) when all the LED blocks are lit, and the initial time of shipment (initial) when the LED blocks are individually lit. Individual waveform Ki1 to Ki
n, and further shows a full lighting waveform Ski at the time of temporal adjustment when all the LED blocks are lit.

In the second adjustment method, the waveforms when all the blocks are lit are compared, and adjustment is made so that the output value in the range (2M) of several pixels near the peak position of the individual waveform is closest to the initial value. This is an adjustment method for adjusting the area. Details of the adjustment method will be described below separately for the time of shipment and the time of adjustment.

FIG. 6 is a flow chart showing the flow of the factory adjustment process relating to the second adjustment method. At the time of shipment adjustment, first, a reference medium having a uniform transmittance that simulates a banknote is inserted into the transport path, and each of the LED blocks B1 to Bn is inserted.
Of the D / A converter, and the drive currents of the LED blocks B1 to Bn are adjusted so that the shading becomes the flattest.
B D / A converter setting value Ij (LED block number j
= 1 to n) (step S21). Next, the reference medium is removed from the transport path, all the LED blocks are simultaneously lit with the set value Ij in step S21, and all lit waveforms Si (i: CCD pixel numbers) at that time are obtained. The CCD is set so that the maximum value Smax of all the lighting waveforms falls within the dynamic range (allowable input range) of the A / D converter.
Exposure time Tc and LED lighting time Tl are shortened,
At this time, the shortened CCD exposure time Tcs and LED lighting time Tls are determined and stored (step S22).
Next, the D / A set value Ij in step S21, the CCD exposure time Tcs in step S22, and the LED lighting time Tl
s, the individual waveform Kij (i = CCD) of each LED block
The pixel number, j = LED block number) is obtained, and the peak position (CCD pixel number) Xj (j = LED) of each individual waveform is obtained.
(Step S23). Then, all the LED blocks are simultaneously turned on under the same conditions as in step S23 to obtain a full lighting waveform Si.
i (pixel number and its output value) is stored (step S2).
4).

FIG. 7 is a flowchart showing the flow of the temporal adjustment process relating to the second adjustment method. The time adjustment process performed after shipment is started based on a bill entry detection or discrimination start signal. First, the LED blocks are all turned on, and the entire lighting waveform Ski at that time is obtained (step S31). Here, at the time of shipment or when the aging adjustment has already been performed, each L is adjusted under the same conditions as the previous aging adjustment.
In order to light the ED block, the D / A set value is set to the set value Ij stored in step S21 of FIG. 6 or to the previous time-adjusted value Ikj when the time-adjustment has already been performed, and the CCD exposure time is set. , The LED lighting time is the CCD exposure time Tcs and Ls stored in step S22 of FIG.
The entire lighting waveform Ski is obtained by lighting all the blocks with the ED lighting time Tls. Next, the peak position Xj of each individual waveform stored in step S23 of FIG. 6 is obtained from the acquired full lighting waveform Ski and the initial full lighting waveform Si.
And the total number of output differences between the total lighting waveform Ski at the time of adjusting with time and the initial lighting waveform Si at the beginning (output difference = temporary output / initial output) and the range of the number of pixels at both ends (± M pixels). The sum of squares of the output difference between the full lighting waveform Ski and the initial full lighting waveform Si is calculated (step S32).

Next, the direction of increase / decrease of the D / A set value of each of the LED blocks B1 to Bn is determined based on the sum of the output differences calculated in step S32 (step S33). That is, if the sum of the output differences <0, the D / A set value is incremented by one adjustment unit, and if the sum of the output differences> 0, the D / A set value is decremented by one adjustment unit.
However, if there is a block in which the sum of the output differences = 0, the adjustment of that block is not necessary, so that the D / A set value is not increased or decreased, and the adjustment ends there, and the D / A of each block at that time is ended. Store the set value. Next, the entire lighting waveform Ski is reacquired, and the sum of squares of the output differences of the unfinished blocks is calculated (step S34).

Here, it is determined whether or not there is a block in which the sum of squares of the output difference is larger than the previous value (step S3).
5). If there is a block in which the sum of squares of the output difference is larger than the previous value, the block has a D / A setting value exceeding the value to be set, and the adjustment of the corresponding block ends here. The D / A set value, which is the previous adjustment value, is stored (step S36). Next, it is determined whether or not adjustment of all blocks has been completed (step S3).
7) If all the blocks have been completed, this time-dependent change adjustment process is completed.

If it is determined in step S35 that there is no block in which the sum of squares of the output difference is larger than the previous value, and if it is determined in step S37 that the adjustment of all blocks has not been completed, the adjustment process is continuously performed. There must be. At this time, for blocks for which adjustment has not been completed, D
The / A setting value is further increased or decreased, and the stored adjustment value is set for the block for which adjustment has been completed (step S38). Thereafter, the process returns to step S34, and proceeds to re-acquisition of all lighting waveforms Ski.

Although the first adjustment method and the second adjustment method described above have been described as being executed independently, it is preferable that the first adjustment method and the second adjustment method are executed in combination. Good. In this case, for example, when an impact or vibration is applied to the banknote image reading unit after shipment, the mounting position of the light emitting unit changes, and the peak position of the individual waveform is shifted from the position at the time of shipment. However, the effect of the adjustment error can be reduced by using the two adjustment methods together. The reason will be described below.

FIG. 8 is an explanatory diagram showing an adjustment error due to a defect after the shipment adjustment. If, for some reason, the mounting orientation of the light emitting unit changes or the degree of deterioration of the LEDs in the block changes extremely after shipment, the peak position of the CCD output in the block may change. For example, it is assumed that the peak position at the time of shipment adjustment in the block B1 is Xa, the initial individual waveform at this time is Ki1, and the entire lighting waveform at shipment is Si. Thereafter, it is assumed that the peak position at the time of post-shipment adjustment has moved to Xka.

In this state, the individual waveform at the time of adjustment for each individual block by the first adjustment method is Kki.
If the adjustment amount C is 1, the adjustment amount C is equal to the peak value A1 at the peak position Xa at the time of shipment adjustment and the adjustment individual waveform Kk.
This is the difference from the value of i1. Therefore, when the adjustment is actually performed, the adjustment amount C is adjusted for the individual waveform Kki1 at the time of the adjustment, and in the illustrated example, the adjustment is excessively performed. Therefore, the adjusted individual waveform is Kki1
a, the waveform does not match the initial individual waveform Ki1, and the waveform at the time of full lighting becomes the full lighting waveform Ski protruding only at this block.

Therefore, in the first adjustment method, the adjustment of the single point at the peak position of the individual waveform is performed, and the second adjustment is performed.
Is performed, the output value of the protruding portion of the full lighting waveform Ski is adjusted to be closest to the initial value of the full lighting waveform Si at the time of shipment. With this, even if the peak position of the individual block is different from the peak position stored at the time of shipment,
This can minimize the effect of adjustment.

In the above adjustment method, the current value of the LED block on the light emitting section side is adjusted so that the adjustment error between the output level of the light receiving section and the output level at the time of shipment is eliminated. Processing for further reducing the adjustment error with the output level at the time of shipment will be described.

FIG. 9 is a diagram showing another configuration example of the bill image reading section to which the present invention is applied. In this figure, with respect to each element constituting the bill image reading unit, the same or equivalent element as the constituent element of the bill image reading unit shown in FIG. 1 is denoted by the same reference numeral, and the detailed description is omitted. According to this configuration example, the time-varying adjustment unit 5 includes the set value adjustment processing unit 6, the light emission amount set value storage unit 7, the adjustment condition storage unit 8, the initial value storage unit 9,
And a shading correction coefficient re-correction processing unit 11 in addition to the lighting processing unit 10. Here, the light emission amount setting value storage unit 7 is a block of the LED array of the light emitting unit 1 which is adjusted such that the CCD output is made uniform by using a reference medium having a uniform transmittance when the bill validator is shipped. D / A for each
The set value is stored, and the adjustment condition storage unit 8 stores the CCD exposure time and the LED lighting time when the light emitting unit is controlled and driven so that the CCD output does not saturate in a state where there is no reference medium in the transport path. The storage unit 9 stores a peak position (CCD pixel number) and a peak value of each LED block at the time of the reduced lighting, a factory-set full lighting waveform Si when all the LED blocks are simultaneously subjected to the reduced lighting control, a reference value R and The shading correction coefficient Pi obtained from the CCD output Sri when the reference medium is loaded is stored.

Shading correction coefficient re-correction processing section 11
Is the factory-set full lighting waveform Si stored in the initial value storage unit 9.
The shading correction coefficient Pi is re-corrected based on the shading correction coefficient Pi and the adjusted whole lighting waveform Sei obtained after the adjustment, and the re-corrected shading correction coefficient Pri is output.

The values stored in the light emission amount setting value storage unit 7, the adjustment condition storage unit 8, and the initial value storage unit 9 are the same as those in the first adjustment method and the second adjustment method. This is given in the adjustment process.

The adjustment by the change-over-time adjusting unit 5 of the bill image reading unit is performed by the adjusting process by the first adjusting method or by the second adjusting method.
The shading correction coefficient re-correction processing is performed after the adjustment processing by the adjustment method of the above. Here, the shading correction coefficient re-correction processing is performed after the adjustment processing by the first adjustment method and the adjustment processing by the second adjustment method. Consisting of When the shading correction coefficient re-correction process is performed after the adjustment process using only the first adjustment method, the initial lighting value at the time of shipment adjustment when all the LED blocks are simultaneously shortened and lightened is set as the initial value at the time of shipment adjustment. It is necessary to store Si in the initial value storage unit 9 in advance. Since the adjustment processing by the first adjustment method and the adjustment processing by the second adjustment method are the same as those described above, the shading correction coefficient re-correction processing will be described here.

FIG. 10 is a flowchart showing the flow of the re-correction processing of the shading correction coefficient. First, after the set value adjustment processing section 6 performs the adjustment processing by the first adjustment method and the aging adjustment processing of all the LED blocks by the second adjustment method, the aging change adjustment section 5 re-adjusts after the adjustment at the time of the shortened lighting. Acquire all lighting waveforms Sei (step S4)
1). Next, the shading correction coefficient re-correction processing unit 11
Calculates the adjustment error ratio of the obtained adjusted whole lighting waveform Sei and the factory-set full lighting waveform Si at the time of shortened lighting by the factory adjustment stored in the initial value storage section 9 for all pixels of the CCD ( Step S42). Then, the shading correction coefficient Pi stored in the initial value storage unit 9 is re-corrected with the adjustment error ratio, and the shading correction coefficient Pri actually used for the shading correction is calculated (step S43). The shading correction coefficient Pri re-corrected by the shading correction coefficient re-correction processing unit 11 is represented by the following equation.

[0043]

## EQU2 ## Pri = Pi * Si / Sei (2) After the temporal change adjustment is performed as described above, the raw image data of the banknote read by the waveform acquisition unit 4 is re-corrected. The data is sent to a shading correction processing unit (not shown) together with the shading correction coefficient Pri, where shading correction is performed for each pixel.

[0044]

As described above, according to the present invention, CC
A configuration is adopted in which the change with time of the D output is adjusted using the difference between the peak values of the individual waveforms of each LED block or the area difference between the initial and the elapsed time of all the lighting waveforms. Thereby, the same bill image as the initial state can be always obtained, and stable bill discrimination can be performed.

Further, after the adjustment of each LED block is completed, the shading correction coefficient is corrected again. As a result, an adjustment error with the CCD output at the time of shipment can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a bill image reading unit to which the present invention has been applied.

FIG. 2 is an explanatory diagram illustrating a first adjustment method of a change with time of a CCD output.

FIG. 3 is a flowchart showing a flow of a factory adjustment process relating to a first adjustment method.

FIG. 4 is a flowchart illustrating a flow of a temporal adjustment process related to a first adjustment method.

FIG. 5 is an explanatory diagram showing a second adjustment method of the change with time of the CCD output.

FIG. 6 is a flowchart showing a flow of a factory adjustment process relating to a second adjustment method.

FIG. 7 is a flowchart illustrating a flow of a temporal adjustment process related to a second adjustment method.

FIG. 8 is an explanatory diagram showing an adjustment error due to a defect after shipping adjustment.

FIG. 9 is a diagram showing another configuration example of the bill image reading unit to which the present invention is applied.

FIG. 10 is a flowchart illustrating a flow of a re-correction process of a shading correction coefficient.

FIG. 11 is a diagram illustrating a configuration example of an image reading sensor of the bill validator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-emitting part 2 Light-receiving part 3 LED drive part 4 Waveform acquisition part 5 Temporal change adjustment part 6 Set value adjustment processing part 7 Light emission amount set value storage part 8 Adjustment condition storage part 9 Initial value storage part 10 Lighting processing part 11 Shading correction coefficient Re-correction processing unit 21 Light source unit 22 Light receiving unit 23 Banknote 24 CCD 25 Lens 26 CCD drive circuit 27 Amplification circuit 28 Analog / digital converter (A / D converter) 29 Control circuit 30 Digital / analog converter (D / A conversion) 31) LED drive circuit 32 Transport path

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruhisa Yamada 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Akira Iwamoto 1st Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Fuji Electric Co., Ltd. F term (reference) 2G065 AA04 AA11 AB23 AB28 BA04 BA33 BA34 BC02 BC03 BC19 BC21 BC28 BC33 CA25 DA01 DA15 3E041 AA02 BB02 BB03 CB03 CB07 EA03

Claims (10)

[Claims] 1. A method for adjusting an image reading sensor for detecting a transmitted light of a medium illuminated by a light source controlled to be turned on for each block and reading an image of the medium, comprising the steps of: The exposure time and the lighting time at which the image output is not saturated, and the peak position and the peak value of the image output obtained at the exposure time and the lighting time are obtained in advance for each block as initial values. A method of adjusting an image reading sensor, comprising sequentially lighting the exposure time and the lighting time, and adjusting the light emission amount of the block so that an output value at the peak position matches the peak value for each block. . 2. A method for adjusting an image reading sensor for detecting a transmitted light of a medium illuminated by a light source controlled to be turned on for each block and reading an image on the medium, the method comprising the steps of: Exposure time and lighting time when the image output is not saturated, and the peak position of the image output obtained at the exposure time and lighting time,
The initial image output obtained when all the blocks are turned on at the same time is obtained in advance as an initial value, and when adjusting for aging, an image output is obtained by turning on each block simultaneously with the exposure time and the lighting time for each block. Then, in a predetermined pixel range including the peak position of each block, a total sum of output differences between the output value of the initial image output and the obtained output value of the image output and a sum of squares of the output differences are calculated. The direction of increase or decrease of the light emission amount is determined by the sign of the sum of the output differences,
Adjusting the light emission amount of each block so that the sum of squares of the output difference is minimized. 3. After the adjustment of the light emission amounts of all the blocks is completed, the adjusted image output is obtained by simultaneously lighting all the blocks with the exposure time and the lighting time, and obtaining the adjusted image output and the initial image output. 3. The image reading sensor adjustment method according to claim 2, wherein the adjustment error ratio is calculated, and the shading correction coefficient determined in advance as an initial value is re-corrected by the adjustment error ratio. 4. An adjusting method of an image reading sensor for detecting a transmitted light of a medium illuminated by a light source controlled to be turned on for each block and reading an image of the medium, the method comprising the steps of: The exposure time and the lighting time at which the image output is not saturated, the peak position and the peak value of the image output obtained at the exposure time and the lighting time, and the initial image output obtained when all the blocks are turned on at the same time are previously determined. Obtained as an initial value, when adjusting for a change over time, each block is sequentially lit with the exposure time and the lighting time, and the light emission amount of the block is adjusted so that the output value at the peak position matches the peak value for each block. Adjustment, and furthermore, all the blocks are turned on at the same exposure time and lighting time at the same time, and an image is output. Force, calculating the sum of output differences between the output value of the initial image output and the obtained output value of the image output in a predetermined pixel range including the peak position of each block and the sum of squares of the output difference. Determining the direction of increase or decrease in the amount of light emission for each block based on the sign of the sum of the output differences, and adjusting the amount of light emission of each block so that the sum of squares of the output differences is minimized. How to adjust the sensor. 5. After the adjustment of the light emission amount of all blocks, the adjusted image output is obtained by simultaneously lighting all the blocks with the exposure time and the lighting time, and obtaining the adjusted image output and the initial image output. 5. The adjustment method for an image reading sensor according to claim 4, wherein the adjustment error ratio is calculated, and a shading correction coefficient previously obtained as an initial value is re-corrected by the adjustment error ratio. 6. An adjusting device for an image reading sensor, comprising: a light source section which is divided into a plurality of blocks and is controlled to be turned on for each block; and a light receiving section which receives a transmitted light of a medium and obtains an image output. A light emission amount setting value for storing the light emission amount setting value for each block or the light emission amount setting value after aging adjustment for each block when the light emitting unit is controlled to light so that the image output becomes uniform using a uniform reference medium. Storage means, adjustment condition storage means for storing, for each block, adjustment conditions including an exposure time and a lighting time at which an image output when light lit without the reference medium is received is saturated, and under the adjustment conditions Initial value storage means for storing the peak position and peak value of the obtained image output for each block; and, based on the adjustment conditions stored in the adjustment condition storage means at the time of aging adjustment. Lighting processing means for controlling lighting of the light source unit for each block with the light emission amount set value stored in the light emission amount storage means; and the light emission amount only during the lighting time and the exposure time stored in the adjustment condition storage means The light emission amount setting value storage until the output value at the peak position of the image output for each block obtained when the light emission amount setting value stored in the setting value storage unit is turned on for each block coincides with the peak value. And a setting value adjustment processing unit for updating a light emission amount setting value stored in the unit. 7. An adjusting device for an image reading sensor, comprising: a light source section which is divided into a plurality of blocks and is controlled to be turned on for each block; and a light receiving section which receives a transmitted light of a medium and obtains an image output. A light emission amount setting value for storing the light emission amount setting value for each block or the light emission amount setting value after aging adjustment for each block when the light emitting unit is controlled to light so that the image output becomes uniform using a uniform reference medium. Storage means, adjustment condition storage means for storing, for each block, adjustment conditions including an exposure time and a lighting time at which an image output when light lit without the reference medium is received is saturated, and under the adjustment conditions Initial value storage means for storing an image output when the light source unit is fully lit and a peak position of the image output when individually illuminated for each block; Lighting processing means for performing full lighting control of the light source unit based on the light emission amount set value stored in the light emission amount set value storage means based on the adjustment condition stored in the lighting condition stored in the adjustment condition storage means Time and the exposure time until the output difference in the vicinity of the peak position of the image output for each block obtained when all the lights are turned on with the light emission amount set value stored in the light emission amount set value storage unit is minimized. An adjustment device for an image reading sensor, comprising: setting value adjustment processing means for updating the light emission amount set value stored in the light emission amount set value storage unit. 8. The initial value storage means stores a shading correction coefficient adjusted so that shading when receiving transmitted light from the reference medium is uniform, and light emission of all blocks. After adjusting the amount, calculate the adjustment error ratio between the adjusted image output obtained by lighting all the blocks simultaneously with the exposure time and the lighting time and the image output stored in the initial value storage means, and calculate the initial value storage means. 8. The image reading sensor adjustment apparatus according to claim 7, further comprising a shading correction coefficient re-correction processing unit for re-correcting the shading correction coefficient according to the adjustment error ratio. 9. An adjusting device for an image reading sensor, comprising: a light source unit which is divided into a plurality of blocks and is controlled to be turned on for each block; and a light receiving unit which receives a transmitted light of a medium and obtains an image output. A light emission amount setting value for storing the light emission amount setting value for each block or the light emission amount setting value after aging adjustment for each block when the light emitting unit is controlled to light so that the image output becomes uniform using a uniform reference medium. Storage means, adjustment condition storage means for storing, for each block, adjustment conditions including an exposure time and a lighting time at which an image output when light lit without the reference medium is received is saturated, and under the adjustment conditions Initial value storage means for storing an image output when the light source unit is fully lit and a peak position and a peak value of the image output when individually lit for each block; and Lighting processing means for performing block-by-block or full lighting control of the light source unit based on the light emission amount set value stored in the light emission amount set value storage means based on the adjustment condition stored in the adjustment condition storage means; and the adjustment condition storage. At the peak position of the image output for each block obtained when lighting is performed for each block with the light emission amount set value stored in the light emission amount set value storage unit only during the lighting time and the exposure time stored in the means. While updating the light emission amount set value stored in the light emission amount set value storage unit until the output value and the peak value match, the light emission amount set value stored in the adjustment condition storage means only during the lighting time and the exposure time. Until the output difference in the vicinity of the peak position of the image output for each block obtained when all the lights are turned on with the light emission amount set value stored in the light emission amount set value storage unit becomes the smallest. Emission amount set value and the set value adjustment processing means for updating the light emission amount setting value stored in the storage unit, the image reading adjustment device of the sensor, characterized in that it comprises. 10. The initial value storage means stores a shading correction coefficient adjusted so that shading when receiving transmitted light from the reference medium is uniform, and light emission of all blocks. After adjusting the amount, calculate the adjustment error ratio between the adjusted image output obtained by lighting all the blocks simultaneously with the exposure time and the lighting time and the image output stored in the initial value storage means, and calculate the initial value storage means. 10. The image reading sensor adjustment apparatus according to claim 9, further comprising a shading correction coefficient re-correction processing means for re-correcting the shading correction coefficient according to the adjustment error ratio.