JP3178718B2 - Color image reader - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color image reading apparatus that can be applied to a digital color copying machine, a color facsimile machine, and the like.

(Prior Art) FIG. 9 is a configuration diagram showing a schematic configuration of a conventional color image reading apparatus, in which a document 1 is illuminated by a light source 2 and image light reflected by the document 1 is focused by a lens 4 by a mirror 3. Then, the light enters the dichroic mirror body 5. The image light is split into a plurality of frequency bands by the dichroic mirror body 5. For example, spectral lights divided into three kinds of frequency bands of red, green, and blue are respectively incident on three light receiving elements 6, 7, and 8, and each of the light receiving elements 6 to 8 converts the spectral light into an electric signal. And output it as image data.

In the above-described color image reading apparatus, if the position adjustment of each of the light receiving elements 6 to 8 is not performed with high accuracy, a color shift at the time of reproduction occurs. The position adjustment is performed in both the main scanning direction and the sub-scanning direction, and the adjustment in the sub-scanning direction is performed using a jig during assembly of the apparatus. The adjustment in the main scanning direction is performed on a document with a thin line 9 drawn on the surface as shown in FIG.
As shown in FIG. 11, the waveforms of the read signals 11, 12, and 13 from the light receiving elements 6 to 8 that read the original 10 are displayed on a measuring instrument or the like, as shown in FIG. By changing the timing of the shift (SH) pulse which is one of the above, the peaks P ₁₁ , P 11 of the waveforms of the read signals 11 to 13 are changed.
_12, is performed by matching the position of the P _13.

(Problems to be Solved by the Invention) In the above-described conventional technology, a positional shift amount (color shift amount) is obtained using a jig or the like at the time of assembling the light-receiving elements 6 to 8 that have been mechanically adjusted. Although the above-mentioned position adjustment (color misregistration correction) is performed by setting the value to the internal fixed switch, etc., it is necessary to set the internal fixed switch at the time of assembling. Is generated, and a new adjustment is required even if it is of a degree that can be corrected electrically. Furthermore, there is no means for detecting the occurrence of color misregistration, and there is a problem that errors during reproduction cannot be prevented beforehand.

Further, according to the above-described prior art, the positions of the light receiving elements 6 to 8 can be adjusted in both the main scanning direction and the sub scanning direction.
There are elements that cannot be adjusted by just adjusting them. It is the distance from each light receiving element 6-8 to the lens 4. According to FIG. 9, this is the direction of arrow A. This adjustment of the direction of A
Only by focusing the lens 4 and the light receiving elements 6 to 8
Adjustment with high precision is not possible. If this adjustment is not made, the reduction ratios of the three light receiving elements 6 to 8 will be different. If the reduction ratios are different, a color shift in the main scanning direction occurs. Specifically, when a color shift is corrected at a certain point on the main scanning by the method according to the related art described above, the color shift occurs as the distance from the point increases, even if there is no color shift at that point. Happens.

For example, in the original 10 as shown in FIG. 10, color shift adjustment in the main scanning direction is performed, and adjustment in the sub scanning direction is performed as in the related art, and then several lines are adjusted in the sub scanning direction as shown in FIG. Thin line 9 '
Read the manuscript 10 'on which is drawn. Three light receiving elements 6 to 8
Are different, for example, three light receiving elements 6 to 8
The image data is as shown in FIG. Where 14,15,16
Is image data of the three light receiving elements 6 to 8. In order to perform color misregistration adjustment in the main scanning direction on the original 10 as shown in FIG.
In the vicinity of the main scanning reading start position A, the position of the thin line 9 ′ coincides with each of the image data 14 to 16.
~ 16 gradually deviate. For this reason, a color shift occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color image reading apparatus that can easily and surely prevent the occurrence of color misregistration.

(Means for Solving the Problems) In order to solve the above-described means, the present invention provides a color image reading apparatus that disperses color image light into a plurality of frequency bands and receives the spectral light with a plurality of light receiving elements. A reference plate on which fine lines are drawn in the sub-scanning direction between the main scanning reading start position and the main scanning reading end position, and a read image from one thin line to the other thin line on the reference plate read by each of the light receiving elements. Correcting means for detecting the number of shifted pixels based on the number of pixels and the reference number of pixels in the light receiving element obtained from the data, and performing color shift correction in the main scanning direction according to the number of shifted pixels. .

Further, the present invention is characterized in that the color misregistration correction is performed when power is turned on.

(Operation) According to the present invention, the correction of the color misregistration of the plurality of light receiving elements by the contraction ratio in the main inspection direction is performed based on the read image data from one thin line to the other thin line on the reference plate obtained by each light receiving element. It is performed electrically and automatically by the correction means.

Further, by performing the correction of the color misregistration every time the power is turned on, the occurrence of the color misregistration is reliably prevented.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram schematically showing a reference example for explaining an embodiment of the present invention. Reference numeral 20 denotes an apparatus main body, 21 denotes a contact glass, 22 denotes a document placed on the contact glass 21, 23
Is an index described later provided outside the original reading range of the contact glass 21, 24 is a light source for irradiating the original 22, and 25 is a reflecting mirror for causing the image light reflected by the original 22 to enter the optical unit 26.

FIG. 2 is a plan view showing an example of the index shown in FIG. 1. On the surface of the index 23, a vertical thin line 27 and a horizontal thin line 28 extending in a direction perpendicular to the vertical thin line 27 are formed.

FIG. 3 is an explanatory view of a control system according to this embodiment. Reference numerals 29 and 30 denote lenses and dichroic mirrors provided in the optical unit 26, and 31, 32, and 33 denote dichroic mirrors.
A plurality (three in this reference example) of light receiving the spectral light separated into a plurality of frequency bands (for example, three kinds of red [R], green [G], and blue [B]) from the image light by 30 Element (CC
D), 34, 35, and 36 are analog processing units for performing analog processing on outputs from the CCDs 31 to 33, and 37, 38, and 39 are analog processing units 34.
A / D converters for performing analog / digital (A / D) processing of output signals provided in each of ~ 36, 40 is a line buffer section, 41 is an interface (I / F) section, and 42 is correction means. A CCD control unit, 43 is a line buffer control unit as correction means, 44 is a CPU (central processing unit) as calculation means, 4
Reference numeral 5 denotes a mechanical control unit.

In FIG. 3, the read signals output from the three CCDs 31 to 33 are respectively converted into analog processing units 34 to 36 and an A / D converter 3.
The data is digitized via 7 to 39 and stored in the line buffer unit 40. The data stored in the line buffer unit 40 is sent to the I / F unit 41 at a timing controlled by the CPU 44. The CPU 44 can read part or all of the line buffer unit 40 via the line buffer control unit 43, and can also set the reading start positions of the CCDs 31 to 33 via the CCD control unit 42. .

The color misregistration correction of the present embodiment will be described with reference to the flowchart of FIG. When the power of the apparatus is turned on (S1), each of the CCDs 31 to 33 of the optical unit 26 causes the thin line 27 of the index 23 to be displayed.
Reads (S2), each read signal D _B read occurs in a position displacement of CCD31~33 as shown in FIG. 5, D _R, the peak of the D _G
P _B, P _R, and analyzes and calculated by CPU44 misalignment of P _G is calculated the amount of color misregistration in the main scanning direction (S3). If the CCD control unit 42 can control the CCDs 31 to 33 using the color shift amount as a main scanning correction value (YES in S4), the CCD control is performed (S5). Next, similarly, the horizontal thin line 28 is read (S6), and the CPU 44 analyzes and calculates the color shift amount in the sub-scanning direction (S7). This color shift amount is used as a sub-scanning correction value as a line buffer controller.
If the control of the line buffer unit 40 can be performed in 43 (YES in S8), the line buffer control is performed (S9).

After the color shift correction by the CCD control and the line buffer control described above, the reading of the original 22 by the optical unit 26 is performed (S10). If the result of the main scanning correction value and sub-scanning correction value cannot be corrected by the CCD control unit 42 or the line buffer control unit 43 (NO in S4, N in S8)
O) displays an error by appropriate means (S1)
1).

Therefore, in the above reference example, when the color misregistration after the mechanical adjustment is electrically corrected, it is not necessary to perform the correction work at the time of assembling, and the number of assembling steps can be reduced. In addition, by performing color misregistration correction every time the power is turned on, even if mechanical misregistration occurs after assembly, if electrical correction is possible, the correction is automatically performed, so that it is not necessary to perform readjustment. In addition, since the color shift amount is calculated by the CPU 44, when an uncorrectable color shift occurs, an error display can be performed or the reading operation of the document 22 can be stopped.

FIG. 6 is an explanatory diagram showing a control system in a color image reading apparatus according to an embodiment of the present invention. Members corresponding to those described in the reference example of FIG. 50, the data from the A / D converters 37 to 39 is input,
This is a correction address point setting unit that is a correction unit that outputs correction address point data to be described later to the line buffer control unit 43 under the control of the PU 44.

FIG. 7 is a plan view of a reference plate used in place of the index 23 of the reference example shown in FIGS. 1 and 2. The surface of the reference plate 51 has a vicinity of a main scanning reading start position and a main scanning reading. Fine lines 52 and 53 are formed near the end position in the sub-scanning direction.

The operation of the control system shown in FIG. 6 of this embodiment will be described. First, the adjustment of the positional deviation in the main scanning direction is described with reference to the thin line 52 on the reading start position side of the reference plate 51 as a reference. At this time, if the reduction ratios of the CCDs 31 to 33 are different, the image data of the thin line 53 at the reading end position read by each of the CCDs 31 to 33 is shifted, and as shown in FIG. The number of images l ₁ , l ₂ , from the thin line 52 to the thin line 53 of the data 53, 54, 55
l ₃ will be different. The correction address point setting unit 50 detects how many other pixels l ₂ and l ₃ deviate from the reference pixel number (the pixel number l ₁ in the present embodiment), and then detects the detected deviation pixel. An address point on the main scan to be corrected is set according to the number.

More specifically, for example, in FIG. 8, the method of setting the correction address point for the number of pixels l ₂ is as follows: if the deviation of the number of pixels l _{2 from} the number of pixels l ₁ is △ _nx pixels, Is set to △ n _x pieces.

That is, assuming that the first correction address point is HA _x1 , And the second correction address point is HA _x2 ,
_Assuming that the following correction address points are HA _x3 , HA _x4 ,... HA _xn , The up to the n-th correction address point is set as follows.

Similarly, how to set the correct address point for the pixel number l ₃ is shifted to the pixel number l ₃ with respect to the pixel number l ₁ - is greater than the number of reference pixels △ if n _y pixels (negative values If), from first -th correction address points to the n-th order _{HA y1, HA y2, HA y3} , ... when HA _yn, Set as follows.

As described above, the correction address points (HA _{x1 to} HA _xn ) and (HA _{y1 to} HA _yn ) are set by the correction address point setting unit 50, and the pixels corresponding to the correction address points of the line buffer unit 40 are set by the line buffer control unit 43. to correct.

By the above-mentioned correction, the number of pixels l ₂ is enlarged in the direction A in FIG. 8 by Δn _x pixels as a whole to be equal to the number of pixels l _1, and the number of pixels l ₃ is entirely △ n _y pixels To be decimated,
It is reduced in the B direction and becomes equal to the number of pixels l ₁ . Therefore, the number of pixels l ₁ , l ₂ , l ₃ can be matched, and the CCDs 31 to 33
, The color misregistration due to the reduction ratio in the main scanning direction can be electrically corrected.

(Effects of the Invention) As described above, according to the present invention, it is possible to electrically and automatically correct color misregistration of a plurality of light receiving elements in the main scanning direction, and to perform the color misregistration correction every time power is turned on. Accordingly, it is possible to provide a color image reading apparatus capable of easily and reliably preventing occurrence of color misregistration.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a reference example of a color image reading apparatus for explaining an embodiment of the present invention, FIG. 2 is a plan view showing an example of an index shown in FIG. 1, and FIG. FIG. 4 is a flowchart of a correction operation according to the present embodiment, FIG. 5 is a waveform diagram showing a difference between read signals caused by a position shift of a CCD according to the present embodiment, and FIG. FIG. 7 is an explanatory view showing a control system in a color image reading apparatus according to an embodiment of the present invention. FIG. 7 is a plan view of a reference plate in the present embodiment. FIG. FIG. 9 is a diagram showing a schematic configuration of a conventional color image reading apparatus, FIG. 10 is a plan view of an original for adjustment, and FIG.
FIG. 11 is a waveform diagram showing a difference between read signals caused by the displacement of the CCD shown in FIG. 9, FIG. 12 is a plan view of another original for adjustment, and FIG.
FIG. 3 is an explanatory diagram showing a difference in image data caused by a difference in CCD reduction ratio. 23 ... index, 31, 32, 33 ... light receiving element, 42, 43, 50 ... correction means, 44 ... calculation means, 51 ... reference plate, 52, 53 ... fine line.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/46-1/64

Claims (2)

(57) [Claims] 1. A color image light is divided into a plurality of frequency bands,
In a color image reading apparatus that receives the spectral light with a plurality of light receiving elements, a reference plate in which fine lines are drawn in a sub-scanning direction between a main scanning reading start position and a main scanning reading end position,
The number of shifted pixels is detected based on the number of pixels and the number of reference pixels in the light receiving element obtained from read image data from one thin line to the other thin line on the reference plate read by the light receiving elements, and the number of shifted pixels A color image reading apparatus, comprising: a correction unit that corrects color misregistration in the main scanning direction according to the image data. 2. A color image reading apparatus according to claim 1, wherein said color misregistration correction is performed when power is turned on.