JPS61258559A - Read position measuring system - Google Patents

Abstract

PURPOSE:To measure a read position in the sub-scanning direction of a picture element with finer resolution than the read picture element length by checking the read output of a noted picture element while moving an original by each read picture element length of a CCD in the sub-scanning direction. CONSTITUTION:The original 1 is moved by each read picture element length in the sub-scanning direction so as to allow the noted picture element 7 to read a parallel pattern. As the original 1 is moved, the read output of the noted picture element 7 in the CCD 3 is checked until the noted picture element 7 is best coincident with the black line in the parallel pattern 5 sequentially and the moving amount (d) of the original 1 is stored in this case. It is obtained by the moving amount (d) of the original 1 that the black line read by the noted picture element 7 corresponds to what number of black lines in the parallel pattern 5. When the reference position of the read position is the N-th black line from the edge and the black line read by the noted picture element 7 is the M-th black line, the read position Y of the CCD 3 in the scanning direction is obtained as Y=(M-N)q+d, where (q) is the pitch between the black lines.

Description

[Detailed description of the invention] [Summary] A reading sensor (CO
D) is a method of measuring the reading position, in which multiple black lines with a line width slightly different from an integral multiple of the length of the pixels constituting the COD are measured at the pitch of the reading lines on the document surface. After arranging parallel patterns drawn in parallel with line spacing slightly larger than an integral multiple on the document surface in a direction perpendicular to the sub-scanning direction (main scanning direction), the document is moved in the sub-scanning direction. , while moving the COD by pixel length in the sub-scanning direction, detect a state in which a certain pixel of interest in the CCD matches the black line in the parallel pattern extremely well, and determine the position of the document when a match is detected. The reading position of the pixel of interest in the sub-scanning direction is measured from.

The measurement method using parallel patterns enables highly accurate measurements with a resolution finer than the pixel length.

[Industrial application field]

The present invention provides C
Regarding the CD reading position measurement method, especially in the sub-scanning direction,
The present invention relates to a reading position measuring method that is improved so that the reading position of a CCD can be obtained with high accuracy.

In general, in a reading device such as a facsimile, in order to read a document accurately and with high precision, it is necessary to optically align a target reading line in the sub-scanning direction with a CCD surface. In particular, in order to achieve high-speed and high-resolution reading, we use a split-reading optical system that divides and reads a document using multiple CCDs, and multiple CO2 scanners.
In color reading of the same area of the document in D;'jt In the conventional optical system, it is necessary to align the reading position of the CCD with an accuracy of 174 pixels or more.

Therefore, for the target reading line in the sub-scanning direction, CC
It has been desired to improve the measurement accuracy of the CCD reading position in order to set the reading position of D with high precision.

[Conventional technology]

FIG. 6 is a schematic diagram of a conventional reading position measurement method. As shown in FIG. and at the target position (the position where the image is formed on the CCD 5 when the set position of the CCD 3 is set to the designed position).

C
The reading output of a particular pixel 7 of interest on the CD 3 is examined, and the reading position of that pixel is determined from the difference A between the original position 4 and the position of the document when the thin line pattern 2 is read.

[Problem that the invention seeks to solve]

In this conventional measurement method, the more precisely the reading position is to be determined, the smaller the movement of the document must be. For example, in order to determine the reading position with an accuracy of ±1710 pixels, it is generally necessary to accurately move in steps of about 1 μm, which requires a highly accurate moving mechanism.

Furthermore, as the amount by which the document is moved in each negative movement becomes smaller, the number of movements necessary for one measurement increases accordingly, which increases the disadvantage that the measurement takes time.

The present invention was created in view of these points.
It is an object of the present invention to provide a reading position measuring method that can measure the reading position of a COD in the sub-scanning direction with high precision and a resolution finer than that of the reading pixels with a simple configuration.

[Means for solving problems]

FIG. 1 shows a schematic diagram of a constant force type with four reading positions according to an embodiment of the present invention.

The reading position measurement method shown in Fig. 1 uses a plurality of 51 to 5n black lines with a line width W slightly deviating from an integral multiple of the length of a pixel constituting a CCD as a reading line on the document surface. Parallel patterns 5 are arranged in parallel with a line interval C slightly different from an integral multiple of the pitch of , and the black lines of the parallel patterns 5 are arranged so as to be parallel to the main scanning direction, and are moved in the sub-scanning direction. A lens 6 forms an image of the black line on a CCD 3 surface, and a CCD 3 reads the black line imaged by the lens 6 with pixels arranged in a line at equal pitches.

[Effect]

The document 1 is moved in the sub-scanning direction by the reading pixel length of the CCD 3 in the sub-scanning direction. As the original 1 moves, the change in the reading output that occurs when reading a parallel pattern in which the interval between each black line in the parallel pattern 5 is other than an integral multiple of the reading pixel length is different from each black line in the parallel pattern. Taking advantage of the fact that it is based on the positional relationship with the pixel reading position,
As shown in (b), by examining the read output of a certain pixel 7 of interest, it is detected that the pixel 7 matches the black line 9 extremely well, and from the position of the parallel pattern 5 at that time, the pixel 7 is The reading position is determined with high precision.

〔Example〕

In FIG. 1, a parallel pattern 5 arranged on one side of the original is created by a photographic method, a printing method, or the like.

The distance C between the black lines 51 to 5n of the parallel pattern 5 is C(:,
I) A value slightly deviated from an integral multiple of the reading pixel length in the sub-scanning direction of 3. In this embodiment, it is more than three times as large. The parallel pattern 5 is arranged so that when the document movement amount is O, the position of the black line several grains from the edge of the pattern becomes the reference position (origin) of the reading position. In this embodiment, the positions of the N black lines L1 are assumed to be the reference positions, and the black lines are designated as N.

As shown in Figure 2 (al, (hl), parallel pattern 5
The position of each black line 9 of r11 is indicated by the center line 10 in the line length direction, and the reading position of the pixel 8 is indicated by the center position of that pixel. The reading position of the CCD 3 in the sub-scanning direction is indicated by the amount of deviation from a specific L1 pixel 7 in the CCD 3.

The verification procedure of this example is shown in FIGS. 3 and 4 (a).

This will be explained with reference to a schematic diagram of the reading position measuring method shown in fbl.

In the reading position measurement, it is assumed that the CCD 3 is reading the parallel pattern 5 on the original 1 through the lens 6, as shown in FIG. A in FIG. 3 is a pattern diagram showing that the spout pixels of the CCD 3 are currently detecting the lower side of the parallel pattern.

Next, as shown in FIG. 4 (al), the document 1 is moved by the reading pixel length in the sub-scanning direction shown by the arrow so that the target pixel 7 reads a parallel pattern.

As the document 1 moves, the read output of the target pixel 7 in the CCD 3 is sequentially changed to
The amount of movement d of the document 1 at that time is memorized.

From the amount of movement d of the document 1 described above, it is determined which grain of the black line in the parallel pattern 5 the black line being read by the pixel of interest 7 corresponds to.

Assuming that the reference position of the reading position is the black line N from the end,
If the black line being read by the pixel of interest 7 is the black line with the M grain, when the amount of movement of the document is d and the pitch between the black lines is q, the reading position of the CCD 3 in the scanning direction (deviation from the reference position) )
Y is determined as Y-(M-N) q 10d.

The measurement resolution when measuring the reading position in the sub-scanning direction according to the present invention is determined by the decimal part of the ratio of the reading pixel length P in the sub-scanning direction and the interval C between black lines in the parallel pattern, and can be expressed by the following equation. .

Measurement resolution -c/P-N (pixels) However, N is the integer closest to c/P By measuring the number, the position accuracy can be easily obtained to about ±1710 pixels.

FIG. 5 shows a schematic diagram of a reading position measuring method according to another embodiment of the present invention.

In FIG. 5, the reading positions in the sub-scanning direction are measured for each of the m-th pixel of the CCD 3 and the n-th pixel appropriately distant from pixel m according to the present invention.

As a result, the difference d between the reading positions of pixels m and n in the sub-scanning direction and the distance 11t7 between pixels m and n! are obtained, and from these, the slope θ of the COD with respect to the reading line can be determined with high precision using the following equation.

θ-3in (d/7 [Effects of the Invention]) As explained above, according to the present invention, by checking the reading output of the pixel of interest while moving the document by the reading pixel length in the sub-scanning direction of the CCD, Since the reading position of a pixel in the sub-scanning direction can be measured with high precision at a resolution finer than the reading pixel length, there is no need for a high-precision fine movement mechanism that was required to obtain the same accuracy conventionally, and the number of times Since the number of times the document must be moved for measurement is reduced, faster measurement can be performed.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a reading position measurement method according to an embodiment of the present invention, Fig. 2 FaL (bl is a diagram defining the black border and pixel reading position, Fig. 3 and Fig. 4 (a), mountains) is a schematic diagram for explaining the reading position measuring method of the embodiment, FIG. 5 is a schematic diagram of a reading position measuring method according to another embodiment of the present invention, and FIG. 6 is a schematic diagram of a conventional reading position measuring method. In the figure, 1 is the original, 2 is the thin line pattern, 3 is the reading sensor (CCD), 4 is the original reading position, 5 is the parallel pattern, 51 to 5n are the black lines, 6 is the lens, and 7 is the pixel of interest. , 8
9 indicates a pixel, 9 indicates a black line, and 10 indicates a center line of the black line. Fig. 1 yφ Spring Y Sarato's cover 1 zftr Mug 9 Liu Ding January blade Fig. 2 (G) (b) Komabuchi q Details Atsushi (It> Sword Sword O law to the government □ Speed style edict Figure 4 lacquer release) ℃ hunting line routine (11 okiba' promotion way 6a ceremony; evil figure 5 figure 6

Claims (1)

[Claims] In an image reading device that reads image information of a reading line on the surface of a document (1) with a reading sensor (3) equipped with a large number of pixels arranged in a line at an equal pitch, the width of the pixel is slightly larger than an integral multiple of the width of the pixel. A plurality of lines having a line width and a reference line defining the normal position of the reading sensor (3) are provided in the plurality of lines, and the plurality of lines are set to have a line width that is an integer of the pitch of the reading line. A parallel pattern (5) drawn in parallel with a line interval slightly deviated from the double is formed, and the parallel pattern (5) is aligned in the feeding direction (sub-scanning direction) of the original (1).
is arranged perpendicularly to the document surface, and the document (1) is moved at the reading line pitch so that a predetermined pixel (7) of the reading sensor (3) detects the best read line of the parallel pattern; A reading position measuring method that measures the reading deviation of the reading sensor in the sub-scanning direction based on the distance between the detection line and the reference line, the line interval, and the amount of movement of the document.