JP2718382B2 - Mark sheet reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mark sheet reading apparatus, and more particularly, a binarized mark, which is filled or left blank without being filled, is arranged in a matrix with timing marks for each line. The present invention relates to a mark sheet reading apparatus for reading a mark from a mark sheet provided as described above, and particularly to an improvement in means for correcting the coordinates of read data when the mark sheet is skewed (conveyed while being inclined).

[0002]

2. Description of the Related Art In a conventional mark sheet reading apparatus of this type, as a skew correction means for a mark sheet, a method of physically correcting the inclination of the mark sheet itself by a transport mechanism is generally used. However, such physical skew correction means has a drawback that the size of the entire mark sheet reading apparatus is increased or the cost is high because the transport mechanism is complicated.

On the other hand, Japanese Patent Laid-Open Publication No. Hei 3-15970 discloses means for correcting skew by image processing after reading. FIG. 9 shows the processing method. In the figure, the conveying direction of the mark sheet 50 is the x-axis direction,
Assuming that the direction perpendicular to this is the y-axis direction, the element is 1
The line type image sensors 51 arranged in a row are installed in parallel with the x-axis. On the mark sheet 50, a filled-on mark 52 and an off-mark 53 left blank without being filled are arranged in a matrix, and a filled timing mark 54 indicating each line of the matrix is provided. Are provided on one side edge of the mark sheet 50. Furthermore, on the mark sheet 50,
In front of the first line of the matrix, two filled left and right skew detection marks 55 and 56 are provided at a predetermined interval W.
Is provided. These skew detection marks 55
Reference numeral 56 is located on one line parallel to the matrix line.

Now, it is assumed that the mark sheet 51 is skewed at an angle α with respect to the image sensor 51 in FIG. The image sensor 51 is a mark sheet 50
After reading all the marks above, 2 out of the data
The two skew detection marks 55 and 56 are detected, the difference between the skew detection marks 55 and 56 in the y-axis direction is obtained, and this difference is converted into the number of lines to obtain the number T of skew lines. The triangular ratio (T / W) between T and the interval W between the two skew detection marks 55 and 56 is regarded as the skew inclination α of the mark sheet 50. When correcting the coordinates of each of the on-marks 52 and each of the off-marks 53,
Alternatively, a line before the line to which the off mark 53 belongs is referred to. The reference line is determined as follows.

Assuming that the number of skew lines is T, if the inclination of the mark sheet 51 rises to the right, the image sensor 51
Of the one line of pixel data read at the distance n from the left end to the right, that is, the on mark 52 or the off mark 53 corresponding to this pixel, (T / W) × n lines from the line See previous line. Further, when the inclination of the mark sheet 51 rises to the left, in the one-line pixel data read by the image sensor 51, a pixel located at a distance of n from the right end to the left is (T / W) × Reference the line n lines before. Here, assuming that the number of lines up to the line to be referred to is s, this conventional method uses a triangular ratio of s and n (s /
n) is assumed to be equal to the triangular ratio (T / W) between T and W obtained from the two separated skew detection marks 55 and 56.

[0006]

However, while the interval W between the two skew detection marks 55 and 56 is predetermined, the number T of skew lines is calculated from the data read by the image sensor 51 by two. The three skew detection marks 55 and 56 are detected and obtained from the difference in the y-axis direction. These triangular ratios (T / W) can be said to accurately represent the actual inclination of the mark sheet 51. Absent. That is, when the triangular ratio (T / W) is obtained from only two skew detection marks 55 and 56, that is, only two measurement points, the image sensor 51 reads the skew detection marks 55 and 56 at these two measurement points. In the case where there is an error in the x-axis direction or the y-axis direction, the error at the two measurement points appears as a large error in the triangular ratio (T / W), and the triangular ratio (T
/ W), the skew correction of the coordinates of the ON mark 52 and the OFF mark 53 inevitably results in low correction reliability. The relationship of s / n = T / W is satisfied only when the inclination α of the skew of the mark sheet 51 is small.
Does not hold when the angle becomes large, and when the inclination of the skew of the mark sheet 51 becomes large, the coordinates of the on mark 52 and the off mark 53 are erroneously detected, and accurate skew correction cannot be performed.

An object of the present invention is to accurately measure the angle of a mark sheet when the mark sheet is skewed at an angle,
An object of the present invention is to provide a mark sheet reading device capable of accurately correcting the coordinates of a read binary mark.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a binarized mark is provided in a matrix with timing marks for each line, which are filled or left blank without filling. A mark sheet reading apparatus comprising: a mark sheet; a transport mechanism for transporting the mark sheet; an image sensor that reads a mark on the mark sheet; and a mark detection processing unit that detects and determines a binarized mark from the read data. It is characterized by having the following configuration. That is, on the mark sheet, there are provided linear all-marks which are parallel to the matrix lines and continuous over the entire length of the lines. The mark detection processing unit includes an all-mark detection unit that detects the all-mark by determining a continuous state of dots from data read by the image sensor, and a scanning direction of a pixel of the image sensor on an x-axis. Direction, when the conveying direction of the mark sheet by the conveying mechanism is the y-axis direction, a means for obtaining the x-axis component length L of the all mark detected by the all mark detecting means from the number of dots; Means for detecting a detection time difference T in the axial direction, means for obtaining the substantial length D of the all mark from the detection time difference T, the conveying speed V of the conveying mechanism, and the length L of the x-axis component, and a binarized mark Is corrected based on the ratio between the substantial length D of the all mark and the length L of the x-axis component.

The all mark provided on the mark sheet is a continuous straight line, which is detected by judging the continuous state of the dots from the data read by the image sensor. It can be said that the measurement is performed not only on two measurement points as in the related art but on the same number of measurement points as the number of dots included in the range of the length of the x-axis component of the all mark. Then, the degree of inclination of the all mark detected at such a multi-measuring point is, when assuming two-dimensional coordinates with respect to the read data of the image sensor, the triangular ratio of a right triangle having the all mark as a hypotenuse, that is, the all mark. Can be expressed by the ratio of the substantial length D to the x-axis component length L. Of these two lengths, the x-axis component length L of the all mark is the difference (X ₂ −) between the coordinate X ₁ on the x axis at one end of the all mark and the coordinate X ₂ on the x axis at the other end.
X ₁ ), that is, from the number of pixels between the coordinates of these two points on the x-axis. In this case, since the all mark itself is detected at multiple measurement points, the length L
Is accurate. The following two methods are available for obtaining the substantial length D of the all mark.
Similarly, an accurate value can be obtained.

The first method is that, when the scanning direction of the pixel is an x-axis direction and the transport direction by the transport mechanism is a y-axis direction when the image sensor is a line type, the x-axis component of the all mark obtained earlier is determined. From the length L, the detection time difference T in the y-axis direction at both ends of the all mark, and the transport speed V of the transport mechanism,
The actual length D of the all mark is obtained by the following equation (1).

D = {L ² + (V · T) ² } (1)

In the second method, after the read data of the image sensor is stored in the memory as two-dimensional data in the x-axis direction and the y-axis direction, the coordinates (X ₁ , Y ₁₎ of both ends of the all mark in the two-dimensional data are stored. ) And (X ₂ , Y ₂ ), the actual length D of the all mark is calculated by the following equation (2).
Ask for.

D = {(X ₂ −X ₁ ) ² + (Y ₂ −Y ₁ ) ² } (2)

[0014]

Now, the case of correcting the coordinates (X _n , Y _n ) of one solid on-mark on the n-th line will be described. The x-axis component between the timing mark of the line and the on-mark will be described. Is defined as L _n , and the substantial distance along the line is defined as D _n, and these distances, the substantial length D of the all mark, and the length L of the x-axis component satisfy the following formula (3).

D _n : L _n = D: L (3)

The distance L _n of the x-axis component can be obtained from the number of pixels of the x-axis component between the timing mark and the on mark. On the other hand, real distance D _n along the line can be determined from the following equation (4).

D _n = L _n · (D / L) (4)

Then, based on the ratio (D _n / P _M ) of the obtained distance D _n to a predetermined mark pitch P _M (the interval between marks on the same line), the on-mark is determined to have n lines. It is possible to determine the number of the eye mark. The order of the line is determined by detecting a timing mark.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a mark sheet reading apparatus according to a first embodiment of the present invention together with a mark sheet. In the mark sheet 10, similarly to the related art, a binarized mark that is filled or left blank without filling, that is, a large number of filled on marks 11 and a large number of blank off marks 12. , And the timing marks 13 for each line are arranged in a matrix.
Mark pitch P _M between the mark and the mark of each line is constant and the line pitch P _L between the line and the line
Is also constant. Although the timing mark 13 is provided on the left side edge of the mark sheet 10 in FIG. 1, it may be provided on the right side edge or on both right and left side edges.

Further, the mark sheet 10 is provided with one linear all-mark 14 in front of the above-described matrix-shaped mark arrangement area. The all mark 14 is continuously filled from the left end of the mark sheet 10 to the length of the matrix line in parallel with the matrix line.

The mark sheet reading apparatus shown in FIG. 1 has a line type image sensor 15 that is sufficiently longer than the left and right widths of the mark sheet 10, and a conveyance mechanism that drives the motor 16 to convey the mark sheet 10 in a direction perpendicular to the image sensor 15. A mechanism 17, a reading controller 19 for controlling the reading operation of the image sensor 15 and storing the read data in a memory 18, and a motor 16 for controlling the transport speed of the transport mechanism 17 to be constant. The apparatus includes a timer 20 for measuring the time required for detecting the mark 14 and a mark detection processing unit 21 for detecting and determining the mark from the data stored in the memory 18.

The mark detection processing unit 21 detects an all mark 14 by determining a continuous state of dots from the data stored in the memory 18, and detects an inclination of the detected all mark 14. Skew detector 23 for obtaining a degree (hereinafter, referred to as “inclination ratio”)
And a skew feed correcting unit 24 that corrects the coordinates of the on mark 11 based on the inclination rate of the all mark 14, and a discrimination processing unit 25 that performs a predetermined discriminating process or the like on the corrected mark.

Now, assuming two-dimensional coordinates where the scanning direction of the pixels of the image sensor 15 is the x-axis direction and the transport direction of the mark sheet by the transport mechanism 17 is the y-axis direction, the mark sheet 10 is shown in FIG. Ascending or as in Figure 3
As shown in (2), if it is skewed upward at an angle α, the all mark 14 is also inclined by the same angle α with respect to the x-axis. Here, assuming a right-angled triangle having the all mark 14 as the hypotenuse, the length of the hypotenuse (the substantial length of the all mark 14) is D, and the length of the horizontal side parallel to the x axis (x of the all mark 14). Axis component length) is L, the length of a vertical side parallel to the y axis (y of the all mark 14)
Assuming that H is the length of the axial component), given L and H,
The angle α can be obtained from the triangular ratio between L and H.
Can be obtained from L and H by the following equation (5).

D = √ (L ² + H ² ) (5)

Therefore, the mark sheet reading device of FIG.
First, the all mark 14 is detected from the data read by the image sensor 15 and stored in the memory 18, L is obtained from the x-axis coordinates of both ends thereof, and the detection time difference T in the y-axis direction of the both ends is obtained. The process for obtaining H from the transport speeds V and V will be described with reference to the flowchart of FIG. Here, a variable representing the number of dots of the read data of the image sensor 15 is n, its maximum value is n _MAX ,
It is assumed that a variable representing the x-axis coordinate of a certain dot is x _n , a variable representing the y-axis coordinate is y _n , a variable representing the value of the timer 20 shown in FIG. 1 is t, and a dot detection flag is FL. The timer 20 always counts up.

In FIG. 4, first, in step S1, x _n and y _n are cleared as initial settings, and n = 0,
FL is set to 0, and the timer 20 is cleared to t = 0 in step S2, and then the presence or absence of a dot is determined in step S3. If there is a dot, the process proceeds to step S4, where the x-axis coordinate of the dot is substituted for _xn ,
The variable y _n in the y-axis coordinate, substituting the product (V · t) of the value t of the conveying speed V and the timer 20 of the transfer mechanism 17, also n =
n is incremented as n + 1, and FL =
After setting the dot detection flag to 1 and returning to step S3, the same operation is repeated by moving the coordinates for detecting the dot related to the all mark 14.

If there is no dot in step S3, it is determined in step S5 whether or not the flag FL is 0. If FL = 0, the flow returns to step S2. With FL is substituting n-1 to n _MAX proceeds to not 0 step S6, since by substituting the current value t of the timer 20 in the detection time difference T in step S7, in step S8 the angle α of the following Formula (6)
Ask by

Α = tan ⁻¹ {(V · T / (x _MAX −x ₀ ))} (6) where x ₀ is the x-axis of the dot first found in steps S3 and S4. The coordinate value, x _MAX, is the x-axis coordinate value of the last found dot.

Next, from step S9 to step S14, the dot continuity is confirmed to detect that the mark is the all mark 14. First, in step S9, n = n
After the value is set to 0, n is incremented in step S10, and the process proceeds to step S11. In this step S11, the x-axis coordinate value and y-axis coordinate value of the n-th dot are x _n and y _n , and the x-axis coordinate value and y-axis coordinate value of the first dot are x
_{Assuming 0} and y ₀ , it is determined whether or not the following equation (7) is satisfied.

Tan ⁻¹ {(y _n −y ₀ ) / (x _n −x ₀ )} = α (7)

If this is satisfied, the process proceeds to step S12, where the n-th dot is determined to be a part of the all mark 14, and if not, the process proceeds to step S13 to determine that the dot is not a part of the all mark 14. . If it is determined that the mark is a part of the all mark 14, it is determined whether or not n = n _MAX in the next step S14. If not n _MAX , the process returns to step S10, and n is incremented and the same processing is repeated. When n = n _{MAX in} step S14,
Since the all mark 14 is finally detected, the process proceeds to step S16, where (x _MAX −x ₀ ) is substituted for the x-axis component length L of the all mark 14, and
The substantial length D of the all mark 14 is obtained by the above equation (1).

In the mark sheet reading apparatus of FIG. 1, the substantial length D of the all mark 14 and the length L of the x-axis component
Then, the timing mark 13 and the on-mark 11 are detected to determine the coordinates of the on-mark 11, and the processing will be described with reference to the flowchart of FIG. Note that this flowchart illustrates an example in which the mark sheet 10 is skewed upward to the right as shown in FIG.

In FIG. 5, after the read data relating to all the marks is stored in the memory 18 in step S21,
In the next step S22, all marks 1 for which detection has been completed
The dot having the smallest coordinate in the x-axis direction except for the dot related to No. 4 (corresponding to the timing mark 13 on the first line)
Is retrieved from the memory 18 and the coordinates are retrieved as (x _T ,
y _T ). Further, in the next step S23, the next smaller coordinate in the y-axis direction than y _T dots (on mark 1
1 corresponding to (x _s ,
y _s ). Thereafter, in step S24, the distance D _n is obtained from the following equation (8).

D _n = (x _s −x _T ) · (D / L) (8)

Next, in step S25, this distance D _n
Then, the position of the on-mark 11 is calculated from the ratio (D _n / P _M ) to the predetermined mark pitch P _M (the interval between marks on the same line). The dot related to the on-mark 11 for which the calculation has been completed is deleted from the memory 18 in the next step S26.

In the next step S27, y dot small coordinate in the y-axis direction is determined whether still there in the memory 18 than _T, the next on the mark on the same line returns to step S23 if there 11 Is calculated in the same manner. If not, it means that the processing of the first line has been completed, and the process proceeds to step S28, and it is determined whether or not there is a dot having the next smallest coordinate in the x-axis direction. If there is, the process proceeds to step S29, and the dot having the smallest x-axis coordinate (corresponding to the timing mark 13 of the second line in this case) is searched from the memory 18 and the coordinates are found as (x
_(T , y _T ), the process returns to step S23, and the position of the on-mark 11 of the second line is calculated in the same manner as described above. By repeating such an operation, the position of the on-mark 11 of each line is calculated one by one. Step S
If there is no dot having the next smallest coordinate in the x-axis direction at 28, it means that the timing mark 13 has disappeared, and the process ends.

FIG. 6 shows a mark sheet reading apparatus according to a second embodiment of the present invention. This mark sheet reader is
A matrix-type image sensor 35 that captures an image at a time as a range that satisfies the entire area of one mark sheet 10 as an imaging range 30, and controls a reading operation of the image sensor 35 to read two-dimensional data of the imaging range 30. And a mark detection processing unit 41 for detecting and determining a mark from the two-dimensional data stored in the memory 38. FIG. 7 schematically shows the storage state of the memory 38. In FIG. 6, a transport mechanism for transporting the mark sheet 10 is omitted.

The mark detection processing section 41 includes an all mark detection section 42 for detecting the all mark 14 from the data stored in the memory 38, and an all mark 14
A skew detection unit 43 for calculating the inclination ratio of the mark, a skew correction unit 44 for correcting the coordinates of the on-mark 11 based on the inclination ratio of the all mark 14, and a predetermined discriminating process for the corrected mark. And a determination processing unit 45 for performing the determination.

The mark sheet reading apparatus shown in FIG.
First, from the two-dimensional data stored in
4 is detected, and all marks 14 are detected from the x-axis coordinates at both ends.
The length L of the x-axis component is calculated, and the substantial length D of the all mark 14 is calculated from the x-axis coordinates and the y-axis coordinates of both ends. The processing will be described with reference to the flowchart of FIG. Here, a variable representing the value of the x-axis coordinate of a certain point is X, a variable representing the value of the y-axis coordinate is also Y, a variable representing the number of data dots is n, a maximum value thereof is n _MAX , and a certain dot is represented. Let x _{n be} a variable representing the x-axis coordinate and y _n be a variable representing the y-axis coordinate.

In FIG. 8, first, at step S31, Y =
Then, in step S32, Y = Y + 1 is set, and the y-axis coordinate value Y is incremented.
= 0, and in step S34, X = X + 1 and x
The axis coordinate value X is incremented. And step S
35, it is determined whether the point indicated by the x-axis coordinate value and y-axis coordinate values after increment (X, Y) on whether a dot is present, if there proceeds to step S36, that time x _n The x-axis coordinate value X of y to y _n coordinate value Y at that time
Are substituted, and n is incremented by n = n + 1. Then, the process returns to step S34 to move the detection coordinates in the x-axis direction, and then proceeds to steps S34, S35, and S3.
Step 6 is repeated.

The process proceeds to step S37 If a dot no in step S35, x-axis coordinate value X is determined whether the difference is less than the maximum value X _MAX, step step S3 smaller
4, the process of steps S34, S35, S36, and S37 is repeated. If x-axis coordinate value X in step S37 has reached the maximum value X _MAX, the process proceeds to step S38, Y-axis coordinate value Y is judged whether or not the maximum value Y _MAX smaller, the process returns to step S32 is smaller step The processing from 32 to step S38 is repeated.

In step S38, the y-axis coordinate value Y becomes the maximum value Y
_{When MAX} is reached, detection of all dots relating to the all mark 14 has been completed in both the x-axis direction and the y-axis direction, so that the process proceeds to step S39 and n _MAX = n−
Then, in step S40, the angle α is obtained by the following equation (9).

Α = tan ⁻¹ {(y _MAX −y ₀ ) / (x _MAX −x ₀ )} (9) where x ₀ is the dot first found in steps S 35 and S 36. , _XMAX is the x-axis coordinate value of the dot found last.

In the following steps S41 to S46, the dot continuity state is confirmed to detect the all mark 14, and the processing is the same as the processing in steps S9 to S14 shown in FIG. Therefore, the description is omitted.

When the all mark 14 is finally detected by the processing from step S41 to step S46,
Proceeding to step S47, (x _MAX -x ₀ ) is substituted for the x-axis component length L of the all mark 14, and the substantial length D of the all mark 14 is determined by the equation (2).

Thereafter, the mark sheet reading apparatus of the second embodiment also detects the timing mark 13 and the on-mark 11 and performs the processing shown in FIG. Ask.

[0048]

As described above in detail, according to the present invention, the mark sheet is provided with linear all-marks which are parallel to the lines of the binarized marks provided in a matrix and are continuous over the entire length of the line. Since the all mark is detected by judging the continuous state of the dots from the data read by the image sensor, the skew detection in the present invention is not simply two measurement points as in the related art, but is an all mark. It can be said that the measurement is performed for the same number of measurement points as the number of dots included in the range of the length of the component in the x-axis direction. Then, since the substantial length D and the x-axis component length L of the all mark detected at such multiple measurement points are obtained from the data of the image data, each of these lengths indicates an accurate value, Since the coordinates of the binarized mark are corrected on the basis of the ratio of these lengths, the correction can be performed accurately and with much less error than in the past.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a mark sheet reading apparatus according to a first embodiment of the present invention together with a mark sheet.

FIG. 2 is a plan view showing a mark sheet that is skewed upward to the right.

FIG. 3 is a plan view showing a mark sheet that is skewed upward and to the left contrary to FIG. 2;

FIG. 4 is a flowchart showing a process of detecting an all mark and calculating a substantial length D and an x-axis component length L by the mark sheet reading apparatus of FIG. 1;

FIG. 5 is a flowchart showing a coordinate correction process performed after the process shown in FIG. 4;

FIG. 6 is a block diagram showing a mark sheet reading apparatus according to a second embodiment of the present invention together with a mark sheet.

FIG. 7 is a schematic diagram illustrating a storage state of a memory illustrated in FIG. 6;

8 is a flowchart showing a process of detecting an all mark and calculating a substantial length D and an x-axis component length L by the mark sheet reading apparatus of FIG. 2;

FIG. 9 is a schematic diagram for explaining a skew feeding correction method using a conventional mark sheet reading apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 mark sheet 11 on mark 12 off mark 13 timing mark 14 all mark 15/35 image sensor 17 transport mechanism 18/38 memory 21/41 mark detection processing unit 22/42 all mark detection unit 23/43 skew detection unit 24/44 Skew correction unit 25/45 Discrimination processing unit

Claims (2)

(57) [Claims] 1. A mark sheet provided with binarized marks, which are filled or left blank without being filled, are arranged in a matrix together with timing marks for each line, and the mark sheet is conveyed. A mark sheet reading apparatus comprising: a transport mechanism; an image sensor that reads a mark on a mark sheet; and a mark detection processing unit that detects and determines a binarized mark from the read data. And a continuous linear all mark having a length extending over the entire length of the line in parallel with the mark, and the mark detection processing unit determines the continuous state of dots from data read by the image sensor. All mark detection means for detecting an all mark; and When the inspection direction is the x-axis direction and the transport direction of the mark sheet by the transport mechanism is the y-axis direction, a means for obtaining the x-axis component length L of the all mark detected by the all mark detecting means from the number of dots, Detection time difference T in the y-axis direction at both ends of the mark
Means for determining the substantial length D of the all mark from the detection time difference T, the transport speed V of the transport mechanism, and the length L of the x-axis component. And a skew correcting means for correcting based on the ratio of the substantial length D to the x-axis component length L of the mark sheet. 2. A mark sheet provided with binarized marks, which are filled or left blank without filling, are arranged in a matrix with timing marks for each line, and the mark sheet is conveyed. A mark sheet reading apparatus comprising: a transport mechanism; an image sensor that reads a mark on a mark sheet; and a mark detection processing unit that detects and determines a binarized mark from the read data. A linear all mark that is continuous with the entire length of the line in parallel with the memory, a memory that stores the read data of the image sensor as two-dimensional data in the mark detection processing unit, and a memory that stores the data in the memory. By determining the continuous state of dots from the obtained two-dimensional data, And all mark detecting means for detecting over click, the x-axis and y-axis coordinates of the two-dimensional data stored in the memory, of all the mark x
Means for determining the axial component length L and the substantial length D; and skew correcting means for correcting the coordinates of the binarized mark based on the ratio between the x-axis component length L and the substantial length D of the all mark. The mark sheet reader according to claim 1, further comprising: