JP2003008837A - Skew-detecting method for image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease man-hours for skew adjustment. SOLUTION: In the skew-detecting method for an image pickup device, equipped with a conveying means which conveys a medium in a vertical scanning direction, an LED 1 which irradiates the medium with light, and a CCD sensor 4, which photodetects and converts light reflected by the medium into an electrical signal, the image pickup device is connected to an arithmetic means 12, then a reference medium 10, where lines are printed at equal intervals in the vertical scanning direction, is conveyed by the conveying means; and the CCD sensor 4 receives the light reflected by the reference medium 10, converts reflected light received on scanning lines arrayed in a horizontal scanning direction into an electrical signal, and outputs the signal to the arithmetic means 12, which is made to compute the angle of skew from the number of intersections of the scanning lines of the CCD sensor 4 and the lines of the reference medium 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to skew adjustment in an optical system image reading sensor (hereinafter referred to as an image sensor).

[0002]

2. Description of the Related Art Conventionally, in a bill recognizing device, an optical character reading device (hereinafter referred to as an OCR), an image sensor has a sub-scanning direction (a medium carrying direction is a sub-scanning direction and is orthogonal to the sub-scanning direction). Direction is defined as the main scanning direction), and the linear light from the light source is used for the main scanning of the medium. Illuminated in the direction.

The line-shaped light transmitted or reflected by the medium is reflected by a reflecting mirror, and the reflected light is received by an image pickup means (for example, a CCD sensor, which will be described below by using a CCD sensor) by a lens. It is focused on the surface. The reflected light focused on the light receiving surface is scanned by the CCD sensor in the main scanning direction and output as an image pattern.

However, a skew is generated in the main scanning direction due to the mounting error of the CCD sensor, the accuracy of the sensor fixing component itself, the mounting direction error of the mirror, and the like. This skew adjustment is performed by repeating trial and error by hand so that the skew amount becomes almost zero. Therefore, there is a problem that it takes a lot of adjustment man-hours.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reduce the number of steps for adjusting the skew.

[0006]

A transport means for transporting a medium in the sub-scanning direction, a light source for irradiating the medium with light, and an imaging means for receiving the reflected light reflected from the medium and converting it into an electric signal. In the skew detecting method for an image pickup device, the method is connected to a computing means, and the carrying means carries a reference medium on which a plurality of lines are printed at equal intervals in the sub-scanning direction, and the imaging means reflects the reference medium from the reference medium. The reflected light received is received, and the reflected light received on the scanning line arranged in the main scanning direction is converted into an electric signal and output to the arithmetic means, and the arithmetic means causes the scanning line of the imaging means and the reference medium to be output. The skew angle is calculated based on the number of intersections of the lines.

The skew angle θ is defined by the length W of the scanning line of the image pickup means and the line interval L of the reference medium.
From the number n of intersections of the scanning lines of the image pickup means and the lines of the reference medium, sin ⁻¹ (n × L / W) ≦ θ <si
It can be calculated as n ⁻¹ ((n + 1) × L / W).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) The configuration of the first embodiment will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of an image sensor. In FIG. 1, reference numeral 1 denotes an LED for irradiating a medium with linear light, which is linear in the main scanning direction while moving relatively to the medium in the sub-scanning direction orthogonal to the main scanning direction of the medium. The emitted light is emitted.

Reference numeral 2 is a mirror for refracting an optical path to emit linear reflected light in a predetermined direction, and 3 is an optical system lens for condensing the reflected light to form an image. A CCD sensor 4 receives the reflected light condensed by the optical system lens 3 on its light receiving surface and scans the reflected light in the main scanning direction under the control of the CCD substrate 5 to convert it into an electric signal for each pixel. And the light receiving surface is located at the image forming position.

Reference numeral 6 is an A / D converter for converting an analog signal output from the CCD sensor into a digital signal. 8
Is a mount for fixing the CCD substrate 5 to which the CCD sensor 4 is attached and other components, 9 is a medium running guide, 10 is a reference medium, 11 is display means, and 12 is calculation means.

FIG. 2 is a diagram showing a reference medium in the first embodiment. The reference medium 10 has a length equal to or less than the effective visual field width in the main scanning direction and is drawn at equal intervals L in the sub scanning direction. In addition, for example, a plurality of black lines are printed. The operation of the first embodiment having the above configuration will be described below. First, when the reference medium 10 is set by abutting against the traveling guide 9, the reference medium 1 moving in the sub-scanning direction is set.
LED 0 emits linear emission light in the main scanning direction.

The line-shaped emitted light with which the reference medium 10 is irradiated hits the reference medium 10, the reflected light is reflected by the mirror 2 and condensed by the optical system lens 3, and the CCD sensor 4 is used.
An image is formed on the light receiving surface of. And the CCD sensor 4 is CC
The reflected light is scanned in the main scanning direction under the control of the D substrate 5 to be converted into an electric signal for each pixel to detect an image pattern (hereinafter, the image pattern of the reference medium 10 is referred to as a line image). .

The analog signal acquired by the CCD sensor 4 is converted from an analog signal to a digital signal by the A / D converter 6. The signal is input to the display means 11 such as an oscilloscope. And the display means 11
Is displayed so that the number of intersections between the scanning lines of the CCD sensor 4 and the lines of the reference medium 10 can be identified.

FIG. 3 shows the CCD sensor 4 according to the first embodiment obtained by observing the output signal of the CCD sensor 4 displayed on an oscilloscope as a kind of the display means 11.
3A and 3B are diagrams showing the output waveforms of FIG. 3A, FIG. 3A shows the case where the skew amount is zero, and FIG. 3B shows the case where the skew occurs. Since the output voltage V in the black line portion printed on the reference medium 10 is smaller than the output voltage V in the ground portion (for example, white) of the reference medium 10, when the skew amount is zero, that is, CCD
When the scanning line of the sensor 4 coincides with the line of the reference medium 10, the output voltage becomes constant at a small value as shown in FIG.

When there is a skew, for example, when the scanning line of the CCD sensor 4 intersects with the line of the reference medium 10 at three points, the output voltage V drops at three points as shown in FIG. 3B. Waveform is obtained. Below, CC
A method of obtaining the skew amount using the output waveform of the D sensor 4 will be described with reference to FIG.

When the scanning line of the CCD sensor 4 passes through the line of the reference medium 10 and the output voltage V drops, the number of waveforms is n,
When the line interval of the reference medium 10 is L, the reference medium 1
The skew length δ at 0 is n × L ≦ δ <(n +
1) × L, the skew angle θ in the reference medium 10 is sin ⁻¹ (n × L / W) ≦ θ <sin ⁻ , where W is the length of the scanning line of the CCD sensor 4. ¹ ((n + 1) × L / W) ... (*)

Therefore, from the output waveform of the CCD sensor 4, the number n of waveforms in which the output voltage V drops is obtained, and the skew angle θ of the reference medium 10 is obtained from the above-mentioned equation (*).
The attachment angle of the CCD sensor 4 may be adjusted by θ °.
As described above, according to the first embodiment, since the skew amount can be calculated, the adjustment man-hour can be reduced.

Although an oscilloscope is used as the display means 11 in the above description, a display or a count display may be used instead. For example, if a personal computer (not shown) is used, the number of intersections of the scanning lines of the CCD sensor 4 and the lines of the reference medium 10 is counted, and the counted numerical values are displayed on these display means 11. good.

By the way, in the above description, the skew angle
Although (including the skew amount) is calculated manually, it is also possible to calculate it by the calculating means 12 such as a personal computer shown in FIG. That is, the output signal from the CCD sensor 4 converted into a digital signal by the A / D converter 6 is input to the arithmetic means 12, and the arithmetic means 12 crosses the scanning line of the CCD sensor 4 and the line of the reference medium 10. The number of intersections is counted, and the reference medium 10 is calculated based on the formula (*) described above.
The skew angle θ may be calculated.

(Second Embodiment) In the second embodiment, the CCD sensor 4 reads the reference medium 10 whose lines are shaded as shown in FIG. 5 in the first embodiment. is there. Figure 6 shows a CCD with an oscilloscope
It is a figure which shows the output waveform of the CCD sensor 4 in 2nd Embodiment obtained by observing the output signal of the sensor 4.

As shown in FIG. 6, for example, the reference medium 10
When the line is darkened in order from the upper stage to the lower stage and the output voltage V of the CCD sensor 4 is gradually reduced, it can be seen that the reference medium 10 is inclined to the right upward with respect to the main scanning direction. . As described above, according to the second embodiment, by observing the output signal of the CCD sensor 4 using the reference medium 10 in which the lines are shaded,
It is possible to recognize which side the reference medium 10 is tilted from the obtained output waveform.

In the above-described first and second embodiments, the skew amount per bit is calculated from the obtained skew amount, and the calculated skew amount is stored in a memory (not shown) provided on the CCD substrate 5. deep. Then, the angle correction is performed by the value obtained by multiplying the number of pixels in the main scanning direction of the image acquired by the CCD sensor 4 by the skew amount per bit held in the memory.

As a result, even if there is a skew at the time of image acquisition, it is stored in the memory in advance.
Since the skew of the acquired image is adjusted based on the amount of skew per bit, the number of adjustment steps can be reduced.

[0024]

As described above, according to the present invention,
Since the skew amount can be calculated, the adjustment man-hour can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an image sensor.

FIG. 2 is a line of a reference medium according to the first embodiment.

FIG. 3 is a diagram showing an output waveform of a CCD sensor according to the first embodiment.

FIG. 4 is an explanatory diagram for obtaining a skew amount.

FIG. 5 is a line of a reference medium that has been shaded in the second embodiment.

FIG. 6 is a diagram showing an output waveform of a CCD sensor according to the second embodiment.

[Explanation of symbols]

1 LED 2 mirror 3 Optical system lens 4 CCD sensor 5 CCD substrate 6 A / D converter 8 mounts 9 Travel guide 10 Reference medium 11 Display means 12 Computing means

Claims (4)

[Claims] 1. An image pickup apparatus comprising: a conveying unit that conveys a medium in a sub-scanning direction; a light source that irradiates the medium with light; and an image pickup unit that receives reflected light reflected from the medium and converts the reflected light into an electric signal. In the skew detection method, the reference means is connected to a display means, and the conveying means conveys a reference medium on which a plurality of lines are printed at equal intervals in the sub-scanning direction, and the image pickup means reflects light reflected from the reference medium. Is received, and the reflected light received on the scanning lines arranged in the main scanning direction is converted into an electric signal and output to the display means, and the display means outputs the scanning line of the image pickup means and the line of the reference medium. A skew detection method for an image pickup apparatus, wherein the number of intersecting points is displayed so that the points can be identified. 2. An image pickup apparatus comprising: a conveying unit that conveys a medium in a sub-scanning direction; a light source that irradiates the medium with light; and an image pickup unit that receives reflected light reflected from the medium and converts the reflected light into an electric signal. In the skew detection method, the reference means is connected to a computing means, and the conveying means conveys a reference medium on which a plurality of lines are printed at equal intervals in the sub-scanning direction, and the image pickup means reflects light reflected from the reference medium. Is received, and the reflected light received on the scanning line arranged in the main scanning direction is converted into an electric signal and output to the arithmetic means, and the arithmetic means intersects the scanning line of the imaging means and the line of the reference medium. A skew detection method for an image pickup device, comprising calculating a skew angle based on the number of intersections. 3. The skew angle θ is the length W of the scanning line of the image pickup means, the interval L between the lines of the reference medium, and the number of intersections between the scanning line of the image pickup means and the line of the reference medium. From n, sin ⁻¹ (n × L / W) ≦ θ <sin ⁻¹
The skew detection method for an image pickup apparatus according to claim 1 or 2, wherein the skew can be calculated as ((n + 1) × L / W). 4. The skew detection method for an image pickup apparatus according to claim 1, wherein the reference medium is shaded for each line so that a tilt direction of the skew can be identified.