JP2002027207A - Image reader, controlling method therefor, memory medium with stored control procedure therefor and data structure for coding and transmitting computer program signals - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of quickly detect the reliability for evaluation of the focus adjusting condition, a controlling method for image readers, a memory medium having stored control procedure for image readers and a data structure for coding and transmitting computer program signals. SOLUTION: An optical sensor unit moving by driving a focus mechanism outputs data of each optical image. The data are taken in to extract contrast data of each optical image therefrom, and the contrast data are compared to evaluate the focus adjusting condition between a manuscript and the sensor unit. Smoothed data of each optical image are extracted from the data of each optical image, and the dispersion among the extracted smoothed data is obtained as an index showing the reliability of the evaluation. The evaluation reliability is quickly detected, using the data of the optical images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for optically reading an image on a document by irradiating a document such as a film with reading light, a control method for the image reading apparatus, and a control procedure for the image reading apparatus. The present invention relates to a stored storage medium and a data structure for encoding and transmitting a computer program signal.

[0002]

2. Description of the Related Art Generally, when an image on a document such as a film taken by a silver halide camera is digitized and taken into a computer, a film scanner (image reading device) is used.
Is used. The types of documents that can be read by the image reading device include a strip film, an APS film,
There are slide mounts and the like, which are loaded into the image reading device while being held by respective dedicated adapters.

FIG. 8 is a diagram showing a state inside the image reading apparatus. An optical sensor unit 83 for scanning the original 81 with the reading light is provided in the image reading apparatus. The optical sensor unit 83 includes an illumination optical system that emits reading light that illuminates the original 81 in a line shape, and a line sensor that is disposed at a position opposite to the illumination optical system with the irradiation area of the reading light on the original 81 interposed therebetween. And

In each of the originals 81, the position of the image storage area 8E (the position in the thickness direction where the emulsion surface of the original 81 is formed) differs depending on the manufacturer, the manufacturing variation, and the storage state. Therefore, in the image reading apparatus, each time the document 81 is loaded, prior to the image reading process for reading the entire image storage area 8E, the optical sensor unit 8 is provided by a focus mechanism using a cam mechanism or the like.
By moving the whole of 3 in the focus adjustment direction, “focus adjustment” for matching the focus of the optical sensor unit 83 on the image storage area 8E is performed.

In the focus adjustment, first, while maintaining the state where the irradiation area of the reading light is located at the center of the original 81, the optical sensor unit 83 is moved to each position (sampling point) in the focus adjustment direction. As data indicating the focus adjustment state of the sampling point, luminance data output by the line sensor at each sampling point is obtained. The data actually used as the data indicating the focus adjustment state is data corresponding to the focus target range 8e (see FIG. 9) near the center of the document 81 among the luminance data for one line (hereinafter referred to as focus target). The luminance data corresponding to the range 8e is “line data”
That. ).

Here, low-frequency components (rough irregularities) indicating the density distribution of a picture appear in line data obtained at a sampling point (focus point) in a focused state, and individual particles on the original 81 are removed. Since even the high-frequency components (fine irregularities) shown clearly appear, the contrast is generally high. On the other hand, in the line data obtained at the sampling point (defocus point) in the out-of-focus state, although a low-frequency component indicating a picture appears, but a high-frequency component indicating an individual particle on the document 81 does not appear. Low contrast.

Therefore, the image reading apparatus extracts contrast data (for example, the sum of absolute values of differences between adjacent pixels) from each line data at each sampling point, and focuses on the sampling point at which the contrast data becomes highest. The focus adjustment process is completed by recognizing the point and moving the optical sensor unit 83 to the focus point.

[0008]

By the way, the position of the focus target range 8e on the document 81 is slightly shifted for each sampling point due to mechanical play or inclination accompanying the movement of the optical sensor unit 83. In addition, the size of the focus target range 8e of the document 81 is slightly different for each sampling point due to the difficulty in keeping the light flux of the reading light constant (see FIGS. 10A and 10B).
Are originals 81 'and 81 "at different sampling points.
The respective upper focus target ranges 8e'8e "are shown.)

[0009] Assuming that the image on the original 81 is a geometric pattern in which the density changes sharply in the sub-scanning direction as shown in FIG. Area).).

In the focus adjustment process performed at this time, if the position or size of the focus target range 8e changes even a little, the picture indicated by the line data changes for each sampling point. The magnitude relationship between contrast data obtained from mutually different pictures cannot be distinguished as to whether it represents the magnitude relation of the contrast of each picture or the magnitude relation of the focus adjustment state.

As a result, there is a possibility that the focus adjustment processing will fail. In fact, when the focus target range 8e is located in the density boundary area (see FIG. 9), the pattern included in the focus target range 8e becomes a pattern in which the black area and the white area are equally included, or a single pattern. It becomes a pattern of concentration,
A pattern in which two densities are included evenly, or a pattern in which two densities are non-uniformly displayed, such that contrast data of different patterns are obtained even at the sampling point where they are in the same focusing state. However, even if they have been done, they will have different values.

Incidentally, the various line data shown in FIG. 11 are all line data obtained in a focused state, but since they show different patterns, the appearance of low frequency components is different. Moreover, in FIG. 11, the appearance of high-frequency components representing individual particles is different. Therefore, it is clear that the focus adjustment processing based on the contrast data may fail.

Therefore, conventionally, when a density boundary area exists in the image of the original 81, the focus target area 8
In some cases, e was located in the density boundary area, causing the focus adjustment process to fail. The failure of the focus adjustment processing is confirmed when the operator sees that the image displayed on the display such as the monitor is blurred after the image reading processing is completed.

In some conventional focus adjustment processing, the focus target range 8e on the document 81 is increased to a plurality of places in order to increase the reliability of evaluation of the focus adjustment state. This is inefficient because the time required for the adjustment process is always extra by the increased amount. Therefore, the present invention provides an image reading device capable of quickly detecting the reliability of evaluation of a focus adjustment state, a control method for the image reading device, a storage medium storing a control procedure for the image reading device, and encoding and transmitting a computer program signal. It is intended to provide a data structure for performing

In particular, the invention according to claims 2, 6, and 10 aims at detecting the reliability of the evaluation of the focus adjustment state more quickly, and it is intended that the invention be described in claims 3, 7, and 10. An object of the present invention is to improve the reliability of an image reading apparatus, and it is an object of the present invention to improve the reliability of an image reading apparatus.
An object of the invention described in (1) is to improve the accuracy of focus adjustment without changing the hardware of the image reading apparatus.

[0016]

An image reading apparatus according to claim 1, which irradiates a document with reading light and forms an optical image formed by light transmitted or reflected by an irradiation area of the document with the reading light. An optical sensor unit for detecting the position, a focus mechanism for changing the positional relationship between the original and the optical sensor unit in the focus adjustment direction, and the optical sensor unit under each of the positional relationships changed by driving the focus mechanism. A sampling unit that captures the data of each optical image to be detected, and a contrast data of each optical image extracted from the data of each optical image detected by the sampling unit and compared to extract the data between the original and the optical sensor unit. And a focus detection unit for evaluating a focus adjustment state of the optical image. The image processing apparatus further includes a reliability acquisition unit that extracts smoothed data of an image and acquires a variation between the extracted smoothed data as an index indicating the reliability of the evaluation by the focus detection unit. .

The variations among the smoothed data indicate variations in changes in the design of each optical image, and the reliability of the evaluation changes depending on the magnitude of the variations. The reliability acquiring means for acquiring such a variation between the smoothed data can reliably detect the reliability of the evaluation by the focus detecting means. Further, the acquisition is performed using the data of the optical image acquired by the sampling means to extract the contrast data.

Therefore, in the image reading apparatus, the reliability of the evaluation of the focus adjustment state can be quickly detected before the focus detection means actually performs the evaluation. According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the reliability acquiring unit extracts flattened data as the smoothed data.

First, the minimum information required to obtain the reliability is not the "picture" of each optical image itself but the "variation of the picture" in each optical image. It is desirable that the value be a value that causes a difference in the picture between the optical images, and that the value be obtained by a calculation as simple as possible. In this regard, the flattening value is a value indicating the magnitude of the non-periodic component from which all the periodic components have been removed from the data of the optical image, and represents the difference in the picture, while the average value of each pixel value (or This is preferable because it can be obtained extremely easily by the sum of the pixel values.

Therefore, the image reading apparatus can more quickly detect the reliability of the evaluation of the focus adjustment state. The image reading device according to a third aspect is the image reading device according to the first or second aspect, further comprising a notifying unit that notifies information to the outside, and the reliability obtaining unit includes:
The obtained variation is compared with a predetermined value, and if the variation is higher than the predetermined value, it is considered that the reliability of the evaluation by the focus detection unit is insufficient, and the notification unit is notified to that effect. It is characterized by having a judgment means for giving an instruction to the user.

Therefore, the operator can regard that the evaluation by the focus detection means is properly performed unless the notification is made by the notification means. Therefore, the reliability of the image reading device that operates based on the evaluation is improved. According to a fourth aspect of the present invention, in the image reading apparatus according to the first or second aspect, the positional relationship between the document and the optical sensor unit is scanned on the document by the irradiation area. Further comprising a scanning mechanism for changing in such a direction, the reliability acquiring means compares the acquired variation with a predetermined value, and drives the scanning mechanism when the variation is higher than the predetermined value. It is characterized in that it has a judging means for re-operating the sampling means after changing the position of the irradiation area on the document.

If the position of the irradiation area is moved in this manner, the irradiation area is located on the density boundary area (generally making it difficult to evaluate the focus adjustment state) even during the first operation of the sampling means. However, in the re-operation, it can be removed from the density boundary area. As a result of performing the re-operation as needed, the accuracy of the focus adjustment is improved. Moreover, the comparison by the determination means, the change of the position of the irradiation area, and the instruction of the re-operation can all be realized by processing on software.

Therefore, it is possible to improve the accuracy of focus adjustment without changing the hardware in the image reading apparatus. A control method for an image reading apparatus according to claim 5 irradiates a reading light to a document,
An optical sensor unit that detects an optical image formed by light transmitted or reflected by the irradiation area of the reading light on the original,
A focus mechanism for changing a positional relationship between the document and the optical sensor unit in a focus adjustment direction, the control method for an image reading apparatus, wherein the The original and the optical system are extracted by comparing a sampling procedure for capturing data of each optical image detected by the optical sensor unit and contrast data of each optical image from the data of each optical image captured in the sampling procedure. A focus detection procedure for evaluating the focus adjustment state between the sensor unit and extracting the smoothed data of each optical image from the data of each optical image, as an index indicating the reliability of the evaluation by the focus detection procedure. And a reliability obtaining procedure for obtaining a variation between the extracted smoothed data. To.

According to a sixth aspect of the present invention, in the control method of the image reading apparatus according to the fifth aspect, the reliability obtaining step includes extracting flattened data as the smoothed data. It is characterized by being. A control method for an image reading apparatus according to a seventh aspect is a control method for an image reading apparatus including the optical sensor unit and the focus mechanism according to the fifth aspect, and further including a notifying unit for notifying information to the outside. And a focus detection procedure according to claim 5, and a reliability acquisition procedure according to claim 5 or 6, wherein the reliability acquisition procedure includes the acquired variation and a predetermined value. If the variation is higher than the predetermined value, it is considered that the reliability of the evaluation by the focus detection procedure is insufficient, and a determination procedure for instructing the notification means to notify the user is included. It is characterized by being performed.

[0025] A control method for an image reading apparatus according to an eighth aspect includes the optical sensor unit and the focus mechanism according to the fifth aspect, and the positional relationship between the original and the optical sensor unit is determined by the irradiation area. A control method for an image reading apparatus further comprising a scanning mechanism that changes a direction in which the document is scanned,
It has a sampling procedure and a focus detection procedure according to claim 5, and a reliability acquisition procedure according to claim 5 or 6, wherein the reliability variation procedure includes the acquired variation and a predetermined value. In comparison, if the variation is higher than the predetermined value, a determination step of driving the scanning mechanism to change the position of the irradiation area on the document and re-executing the sampling procedure is included. Features.

The control methods for the image reading apparatus according to the fifth, sixth, seventh, and eighth aspects are respectively applied to the image reading apparatus according to the first, second, third, and fourth aspects. The same operation and effect as those of the reader can be obtained. A storage medium storing a control procedure for the image reading apparatus according to claim 9, irradiates a document with reading light and forms an optical image formed by light transmitted or reflected by an irradiation area of the reading light on the document. A storage medium storing a control procedure for an image reading device including an optical sensor unit for detecting, and a focus mechanism for changing a positional relationship between the document and the optical sensor unit in a focus adjustment direction, wherein A sampling procedure for capturing data of each optical image detected by the optical sensor unit under each of the positional relationships changed by driving, and extracting contrast data of each optical image from data of each optical image captured by the sampling procedure. Comparing the original and the optical sensor unit to evaluate the focus adjustment state between the original and the optical sensor unit. A detection procedure and smoothed data of each optical image are extracted from the data of each optical image, and a variation between the extracted smoothed data is obtained as an index indicating the reliability of the evaluation by the focus detection procedure. And a reliability acquisition procedure.

The storage medium storing the control procedure for the image reading apparatus according to claim 10 is the storage medium storing the control procedure for the image reading apparatus according to claim 9, wherein the reliability acquisition step is performed by the smoothing step. Characterized in that it is a procedure for extracting flattened data as converted data. A storage medium storing a control procedure for the image reading apparatus according to claim 11, further comprising an optical sensor unit according to claim 9, a focus mechanism, and a notifying unit for notifying information to the outside. And a focus detection procedure according to claim 9 and a reliability acquisition procedure according to claim 9 or 10, wherein the reliability acquisition procedure is a storage medium. Comparing the obtained variation with a predetermined value, if the variation is higher than the predetermined value, it is considered that the reliability of the evaluation by the focus detection procedure is insufficient, and It is characterized in that a judgment procedure for giving an instruction to notify the effect is included.

According to a twelfth aspect of the present invention, a storage medium storing a control procedure for the image reading apparatus includes the optical sensor unit and the focus mechanism according to the ninth aspect, and stores a positional relationship between the original and the optical sensor unit. 10. A storage medium storing a control procedure for an image reading apparatus further comprising a scanning mechanism for changing a direction in which the original is scanned by the irradiation area, wherein the sampling procedure and focus detection according to claim 9 are stored. Storing the procedure and the reliability acquisition procedure according to claim 9 or 10, wherein the reliability acquisition procedure compares the acquired variation with a predetermined value, and the variation is larger than the predetermined value. Is higher, it is determined that the scanning mechanism is driven to change the position of the irradiation area on the document and the sampling procedure is executed again. Characterized to include sequentially.

These claim 9, claim 10, and claim 1
According to the first and twelfth aspects of the present invention, there is provided a storage medium storing a control procedure for an image reading apparatus for obtaining the same effect as the image reading apparatus according to the first, second, third, and fourth aspects. Can be provided. 14. The data structure for encoding and transmitting a computer program signal according to claim 13, wherein the document is irradiated with reading light, and the light transmitted or reflected by the irradiation area of the reading light on the document forms an optical structure. Encoding and transmitting a computer program signal including a control procedure for an image reading apparatus including an optical sensor unit for detecting an image, and a focus mechanism for changing a positional relationship between the original and the optical sensor unit in a focus adjustment direction. In the data structure for performing, the control procedure, the sampling procedure to capture the data of each optical image detected by the optical sensor unit under each of the positional relationship changes by driving the focus mechanism,
A focus detection step of evaluating a focus adjustment state between the original and the optical sensor unit by extracting and comparing contrast data of each optical image from data of each optical image captured by the sampling procedure; Along with extracting the smoothed data of each optical image from the data of each optical image, and as an index indicating the reliability of the evaluation by the focus detection procedure, a reliability obtaining procedure of obtaining a variation between the extracted smoothed data, It is characterized by including.

According to the data structure for encoding and transmitting the computer program signal, the computer program signal for obtaining the same effect as the storage medium storing the control procedure for the image reading apparatus according to claim 9 is provided. It becomes possible to encode and transmit.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> First, a first embodiment of the present invention will be described with reference to FIGS. 1, 2, 3, 4, 5, and 6. FIG.

(Configuration) FIG. 1 is a block diagram showing the configuration of an image reading apparatus 1 according to the present embodiment. Image reading device 1
Can be attached externally to the host computer 12 and can be attached to the document 11 in various states such as a slide mount, a strip film, and an APS film via an adapter 14 corresponding to the external shape.

In the image reading apparatus 1, an adapter 14 is fixed to the main body of the image reading apparatus 1, and an image storage area 1E on the document 11 is provided from an optical sensor unit 13 (corresponding to an optical sensor unit in the claims). Scanning is performed by the emitted reading light 1L. The optical sensor unit 13 includes an illumination optical system 13a that linearly illuminates a part of the document 11 with a reading light 1L formed by condensing light emitted from a light source such as an LED, and the like. ,
A line sensor 13d that photoelectrically detects an optical image of an irradiation area by the reading light 1L and other optical systems (a mirror 13b, an imaging lens 13c, and the like) are provided in a predetermined positional relationship.

Here, in this specification, the direction along the optical axis direction of the reading light 1L is referred to as "focus adjustment direction", the longitudinal direction of the irradiation area on the original 11 is referred to as "main scanning direction", and the original 11
The direction that is horizontal to the main scanning direction and perpendicular to the main scanning direction and that corresponds to the main scanning direction of the line sensor 13d is referred to as a “sub-scanning direction”. Further, the optical sensor unit 13 scans the image storage area 1E of the document 11 with the irradiation area of the reading light 1L so that the scanning mechanism 16 (scan motor 1
6a, a lead screw 16b fixed to the rotating shaft of the scan motor 16a, and a guide mechanism for moving the optical sensor unit 13 in the sub-scanning direction with the rotation of the lead screw 16b) in the image reading apparatus 1 in the sub-scanning direction. It is possible.

The optical sensor unit 13 has a focus mechanism 18 (corresponding to the focus mechanism in the claims) for adjusting the focus (optical sensor unit 13).
18c that supports the optical sensor unit 13 in the focus adjustment direction, an AF motor 18b that drives the cam mechanism 18a, etc.) Is attached to the scanning mechanism 16 so as to be able to swing in the focus adjustment direction (the focus mechanism 18 swings the optical sensor unit 13 so that the reading light 1L
Is moved in the focus adjustment direction, but may be a translational structure in which the same function is obtained by moving the optical sensor unit 13 in the focus adjustment direction in parallel. ).

The image reading apparatus 1 further includes an illumination optical system 1.
Illumination drive circuit 21 for driving 3a, line sensor 13d
Processing circuit 2 for processing luminance data output from
3. AF motor drive circuit 2 for driving AF motor 18b
5. Scan motor drive circuit 27 for driving scan motor 16a, and CPU 2 for giving instructions to those circuits
0 (the sampling means, the focus detection means,
Corresponds to reliability acquisition means. ), A memory 20a as a storage area used for each processing of the CPU 20, and the like.

The image reading device 1 is connected to the host computer 12 via the interface circuit 22.
CPU 20 receiving instructions from host computer 12
Executes an image reading process in the image reading device 1. In the image reading process, the CPU 20 gives an instruction to the scan motor driving circuit 27 to
And scanning the original 11 in the sub-scanning direction in the irradiation area of the reading light 1L by moving the optical sensor unit 13 in the sub-scanning direction, while driving the line sensor 13d via the image processing circuit 23, At this time, line data output from the line sensor 13d is sequentially acquired. As a result, the image data in the image storage area 1E is obtained.

Hereinafter, the focus adjustment processing performed prior to the image reading processing will be described in detail. (Operation) FIG. 2 is an operation flowchart of the focus adjustment processing by the CPU 20. FIG. 3 is a diagram for explaining the focus adjustment processing by the CPU 20.

When the focus adjustment process is started, the CPU 20
Drives the scan motor 16a by giving an instruction to the scan motor drive circuit 27, and moves the optical sensor unit 13 in the sub-scanning direction such that the irradiation area of the reading light 1L is located at a predetermined address in the center of the document 11 (step S1). In this state CPU20, such as to drive the AF motor 18b by giving instructions to the AF motor drive circuit 25, the first sampling point (for example, the illumination optical system 13a of each sampling point P _i is closest to the original 11 the optical sensor unit 13 to be positioned at point P ₁₎ is moved in the focusing direction (step S2).

Further, in this state, the CPU 20 drives the line sensor 13d through the image processing circuit 23, and among the luminance data output from the line sensor 13d, the focus target range 1e near the center of the document 11 (the focus range in FIG. 9). line data DL _i corresponding to the same in a) and target range 8e captures via the image processing circuit 23 (step S3).

[0041] From this line data DL _i, CPU20
The extracts a contrast value C _i indicating a focusing state, extracts the smoothed value A _i indicating a pattern, and stores these values in memory 20a in association with the sampling point P _i (step S4, FIG. 3 reference).

The contrast value C _i is obtained, for example, by adding the absolute value of the difference between the pixel values of adjacent pixels of the line data DL _i for the whole. On the other hand, the smoothed value A _i will be described in detail below with reference to FIG. As shown in FIGS. 4A, 4B, and 4C, generally, the waveform of the line data DL (that is, the waveform indicating the density distribution of the focus target range 1e) includes a low-frequency component indicating a picture and a document. 11 are superimposed with high frequency components representing individual particles.

Therefore, the smoothed value A _i to be extracted as information indicating a picture is obtained by removing (smoothing) at least high frequency components indicating individual particles on the document 11 from the line data DL _i . However, the minimum necessary information for obtaining the reliability is not the “picture” at each sampling point P _i itself, but the “variation of the picture” between the sampling points P _i , and thus the smoothed value A It is desirable that _i be a value that causes a difference in the picture between the different sampling points P _m and P _n , and that the value be obtained by a calculation as simple as possible.

Therefore, in this embodiment, the smoothed value A _i is
And flattening value of the line data DL _i. Flat cation is a value indicating the magnitude of the aperiodic component to remove any cyclic component from the line data DL _i, should have different values by design. The high frequency component in the line data DL _i is because those of the individual particles on the original 11 is a waveform which oscillates up and down evenly waveform showing a picture.
Therefore, the most easily calculated flattening value is:
Average value of each pixel value of the line data DL _i (or sum of the pixel values) can be mentioned.

Such a smoothed value A _i can be determined very easily while reliably representing the difference between pictures (hereinafter, the smoothed value A _{i is referred} to as the pixel value of the line data DL _i ). Of the average.)

[0046] Incidentally, substantially between line data DL _a same pattern, DL _b, DL _c of each smoothed value _{A a,} A _b, A _c as shown in FIG. 4 (a), most variations occur 4 (a ′), and as shown in FIG. 4 (b), the line data DL _a , DL _b ,
DL _c each smoothed value _{A a,} A _b, slight variations between the A _c occurs (FIG. 4 (b ')), line data of relatively significantly different pattern as shown in FIG. 4 (c) DL _a , D
L _b, DL _c of each smoothed value _{A a,} A _b, a relatively large variation between A _c occurs (FIG. 4 (c ')). It can also be seen from FIG. 4 that the variation in the smoothed value A _i indicates the variation in the picture.

Returning to FIG. 2, in step S5, the CPU 2
0 is given by giving an instruction to the AF motor drive circuit 25.
The AF motor 18b is driven, and the next sampling point
To P _{i + 1}Optical sensor unit 13
Tep (for example, the distance at the optical axis 1L position is 40 to
(About 50 μm). The CPU 20 executes the first sun
Pulling point P₁From the last sampling point
P_nEach sampling point up to (for example, n = 70)
To P_iIn the above, the line data DL_iAcquisition (step
Step S3), contrast value C_iAnd smoothed value A_iExtraction
(Step S4) is repeated (hereinafter, such a step is performed).
The processing of steps S3 to S6 is referred to as "sampling processing".
Say. ).

[0048] As a result, the contrast value C _i at each sampling point P _i, and the smoothed value A _i is the memory 2
0a (see FIG. 3). CPU20 completing the sampling process, the smoothed value stored in the memory 20a A _1, · · ·, with reference to the A _n, the reliability index ΔA rating focusing state, the smoothed value A _1, · · - obtains a difference (variation) between the maximum value and the minimum value of a _n (step S
7).

As described above, the smoothed values A ₁ ,.
.., _An are sampling points P _{1 ,.}
, The larger the variation,
It tends to be difficult to evaluate the focus adjustment state. Therefore, the smaller the value of the reliability index ΔA, the higher the reliability of the evaluation of the focus adjustment state. The CPU 20 calculates the reliability index Δ
It is determined whether or not A is smaller than a predetermined threshold value ΔA ₀ (step S8). If it is smaller, each of the contrast values C ₁ ,... Stored in the memory 20a at that time is determined. · proceeds regarded as evaluation of the focusing state according to C _n is performed with sufficient confidence to step S9.

When the line data DL _i is expressed by 16 bits, the threshold ΔA ₀ is set to about 2000, and when the line data DL _i is expressed by 8 bits, the threshold ΔA _{0 is set} to 30. It is good to set to about. FIGS. 5A to 5G respectively show the reliability index ΔA _a individually obtained from different documents (or different positions of the same document).
It is a diagram illustrating a ~ΔA _g. Of these, (c), (e),
For (f) and (g), the reliability index ΔA _c ,
Since ΔA _e , ΔA _f , and ΔA _g are kept smaller than the threshold value ΔA ₀ , the reliability of the evaluation of the focus adjustment state is considered to be sufficiently high.

FIG. 6 is a diagram for explaining the evaluation process of the focus adjustment state. In step S9, as the focus adjustment state evaluation processing, the CPU 20 refers to the contrast values C ₁ ,..., C _n stored in the memory 20a, and selects the sampling point corresponding to the maximum contrast value C _f among them. the P _f regarded as a focus point.

[0052] The CPU20 is focusing by moving the optical sensor unit 13 in the focusing direction so as to drive the AF motor 18b by giving instructions to the AF motor drive circuit 25, positioned at the focus point P _f Perform (Step S10) Thereafter, the CPU 20 drives the scan motor 16a by giving an instruction to the scan motor drive circuit 27,
The focus adjustment is performed by moving the optical sensor unit 13 in the sub-scanning direction so that the irradiation area of the reading light 1L is located at the image reading start address on the document 11 so as to maintain a state where the subsequent image reading process can be started. The process ends (step S11).

On the other hand, as a result of the determination in step S8,
When the reliability index ΔA exceeds the threshold ΔA ₀ ,
CPU20 regards at that time contrast data C ₁ stored in the memory 20a, · · ·, evaluation of the focus adjustment state based on C _n and the reliability decreases, the step S
The process proceeds to step S12 without executing step S9. According to this determination (step S8), when it is difficult to evaluate the focus adjustment state, such as when the focus target range 1e is located in the density boundary area of the image, it is reliably detected.

[0054] Incidentally, FIG. 5 (a), (b) , the reliability index as shown in _{(d) ΔA a, ΔA b} , when the .DELTA.A _d is obtained, in order to exceed the threshold .DELTA.A _0, focusing The state evaluation is considered to be unreliable. In step S12, the CPU 20 drives the scan motor 16a by giving an instruction to the scan motor drive circuit 27, and moves the optical sensor unit 13 in the sub-scanning direction so that the irradiation area of the reading light 1L is shifted by a predetermined line in the sub-scanning direction. Move by a predetermined address.

According to this movement, even if the focus target range 1e is located on the density boundary area in the first sampling processing, it is excluded from the density boundary area when the sampling processing is executed again. In addition,
This movement amount is sufficient for a sufficient distance (for example, about 500 lines,
The distance is preferably 2 mm to 3 mm). As a result of the subsequent sampling processing, the obtained reliability index ΔA
Is smaller than the threshold value ΔA ₀ (step S8 YES), the focus adjustment state evaluation process based on the contrast values C ₁ ,..., C _n stored in the memory 20a at that time (step S9), and The corresponding focus adjustment processing (step S10) is executed.

In FIG. 2 described above, steps S3 to S6 (sampling processing) correspond to the sampling procedure in claims, and steps S7, S8, S12
Corresponds to the reliability acquisition procedure in the claims, and step S
9 (focus evaluation state evaluation processing) corresponds to a focus detection procedure in claims. (Effect) As described above, in the present embodiment, even if the sampling process (steps S3 to S6) is executed, if it becomes difficult to evaluate the focus adjustment state based on the result, the evaluation is actually performed. Before the action is taken,
It is detected based on the magnitude of the reliability index ΔA obtained from the line data DL ₁ ,..., DL _n (step S
8).

Further, since the reliability index ΔA is obtained at a high speed by an extremely simple calculation based on the line data DL ₁ ,..., DL _n , the processing speed of the focus adjustment processing is hardly reduced. In addition, sampling processing is performed as necessary using the reliability index ΔA (steps S3 to S3).
Since S6) is executed again, it is possible to prevent a failure in focus adjustment.

That is, according to the present embodiment, the focus adjustment accuracy is kept high. <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the image reading device 2 of the present embodiment is different from the image reading device 1 of the first embodiment in that a CPU 40
Is equal to

The CPU 40 executes an image reading process in response to an instruction from the host computer 12 similarly to the CPU 20, but the focus adjustment process is partially different from that performed by the CPU 20 (see FIG. 2). FIG. 7 is an operation flowchart of the focus adjustment processing by the CPU 40. 7, steps that are the same as the steps shown in FIG. 2 are given the same reference numerals, and descriptions thereof are omitted here.

The CPU 40 determines that the reliability index ΔA is equal to the threshold value ΔA
NO in step S8 for determining whether or not it exceeds ₀
And before the step 12 of moving the optical sensor unit 13 in the sub-scanning direction, steps S21, S22, S2
Step 3 is performed in order. In step S21, the CPU 40
Notifies the operator that the reliability of the evaluation of the focus adjustment state is low (possibility of focus adjustment failure). This notification is performed by, for example, giving an instruction to the host computer 12 by the CPU 40 and displaying the fact on a display 12 a such as a monitor externally attached to the host computer 12.

The CPU 40 allows the operator to re-execute the sampling process and then evaluate the focus adjustment state on the display 12a (re-execution), or omit the re-execution and evaluate the focus adjustment state. Is also displayed for selecting whether to perform (continue). If the operator determines that it is necessary to perform the focus adjustment with high accuracy based on the type of the image to be read, the operator gives an instruction of “re-execute” to the mouse or the like connected to the host computer 12. If it is determined that there is no need to perform focus adjustment with high precision, an instruction to “continue” can be input.

The CPU 40 proceeds to step S9 when a continuation instruction is input (step S22 YES), and proceeds to step S9 when a re-execution instruction is input (step S23 YES).
Proceed to 12. Note that, in FIG. 7 described above, steps S3 to S6 (sampling processing) correspond to the sampling procedure in claims, and steps S7, S8, S1
Steps S2, S21, S22, and S23 correspond to the reliability acquisition procedure in the claims, and step S9 (focus adjustment state evaluation processing) corresponds to the focus detection procedure in the claims.

As a result of the above description, the operator can regard that the focus adjustment (steps S9 and S10) is properly performed unless the possibility of the focus adjustment failure is displayed on the display 12a. Even if the focus adjustment fails, the failure is not confirmed after the end of the image reading process because the determination is made by the operator in step S22.

That is, the reliability of the image reading device 2 is kept high. <Others> In the above embodiments, the smoothed value A
_i is the average value of each pixel value of the line data DL _i ,
The sum of the pixel values may be used. Also, the line data DL _i
Any data may be used as long as it shows a waveform from which high-frequency components representing individual particles on the document 11 have been removed. However, as described above, it is preferable to set the average value of the pixel values or the sum of the pixel values in order to simplify the calculation (the value of the threshold value ΔA ₀ is also adopted as the smoothed value A _i) . It is determined according to the physical quantity.)

In each of the above embodiments, the smoothed value A _i and the contrast value C _{i at} each sampling point P _i are extracted each time each line data DL _i is fetched (step S3). Line data DL ₁ ,
.., May be extracted collectively after DL _n is taken in. However, according to the latter, all line data DL ₁ ,.
..., it takes a large storage area for storing at one time the DL _n, in that only require storage space to store one line data DL _i, the former is preferable.

In each of the above embodiments, the focus adjustment state evaluation process (step S9) is executed after the reliability index ΔA calculation and comparison process (steps S7 and S8). It may be executed in parallel with the processing. Further, in each of the above embodiments, the image reading process (including the focus adjustment process) is performed by the host computer 12.
May be executed by a CPU in the system. Further, a part of the image reading processing may be executed by the CPU in the host computer 12, and another part may be executed by the CPU in the image reading apparatus. Also, the CP in the host computer 12
U, the operation program is written in the storage medium 12c in advance, and the host computer 12
After having the drive device inside read it, the CPU
(See the lower right of FIG. 1).

A part or all of the above-mentioned operation program can be downloaded from the host computer 12 as driver software or firmware by accessing a predetermined homepage via the Internet. For example, such a download can be performed by selecting a film scanner, which is one of the image reading apparatuses, from the product display on the screen while accessing a predetermined homepage from the host computer 12, or using the OS environment of the host computer 12. This can be performed by selecting driver software or firmware that matches the above.

The following dial-up connection can be applied as a connection form between the host computer 12 and the Internet. That is, the host computer 12
Is connected to a telephone line via a modem or a terminal adapter, and the telephone line is connected to a modem or a terminal adapter of an Internet connection service provider. The provider's modem or terminal adapter is connected to the server, which is connected for 24 hours via a router for setting up a relay route to the Internet. The host computer 12 makes a telephone call when necessary, and connects to the Internet (homepage) via the server of the provider. Note that the connection form between the host computer 12 and the Internet is not limited to such a dial-up connection,
A configuration in which connection with the provider is always established using a dedicated line may be employed.

[0069]

As described above, according to the present invention, the reliability of the evaluation of the focus adjustment state can be quickly detected. In particular,
According to the second, sixth, and tenth aspects of the present invention, the reliability of the evaluation of the focus adjustment state can be detected more quickly, and the third, seventh, and eleventh aspects of the invention. Is
The reliability of the image reading device can be improved, and the invention according to claims 4, 8 and 12 improves the accuracy of focus adjustment without changing the hardware of the image reading device. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of image reading apparatuses 1 and 2.

FIG. 2 is an operation flowchart of a focus adjustment process by a CPU 20;

FIG. 3 is a diagram illustrating focus adjustment processing by a CPU 20.

FIG. 4 is a diagram illustrating a smoothed value A _i .

FIG. 5 is a diagram showing reliability indices ΔA _{a to} ΔA _g obtained from different documents (or different positions of the same document).

FIG. 6 is a diagram illustrating a focus adjustment state evaluation process.

FIG. 7 is an operation flowchart of a focus adjustment process by a CPU 40;

FIG. 8 is a diagram showing a state inside the image reading apparatus.

FIG. 9 is a diagram showing a focus target range 8e.

FIG. 10 is a diagram illustrating a relationship between a light beam of reading light and a sampling point.

FIG. 11 is a diagram comparing line data of different patterns obtained in a focused state.

[Explanation of symbols]

 1, 2 Image reading device 11, 81 Document 12 Host computer 12a Display 12b Input device 12c Storage medium 13, 83 Optical sensor unit 14 Adapter 16 Scanning mechanism 18 Focusing mechanism 1L Reading light 1E, 8E Image storage area 1e, 8e Focus target Range 21 Illumination drive circuit 21 23 Image processing circuit 25 AF motor drive circuit 27 Scan motor drive circuit 22 Interface circuit 20, 40 CPU 20a Memory

Claims (13)

[Claims] 1. A method of irradiating a document with reading light,
An optical sensor unit that detects an optical image formed by light transmitted or reflected by the irradiation area of the reading light on the original; a focusing mechanism that changes a positional relationship between the original and the optical sensor unit in a focus adjustment direction; Sampling means for capturing data of each optical image detected by the optical sensor unit under each of the positional relationships changed by driving of a focus mechanism; and contrast data of each optical image from data of each optical image captured by the sampling means. And a focus detection unit that evaluates a focus adjustment state between the document and the optical sensor unit by extracting and comparing the optical images. Along with extracting the smoothed data of, as an index indicating the reliability of the evaluation by the focus detection means, An image reading apparatus comprising: a reliability obtaining unit that obtains a variation between the extracted smoothed data. 2. The image reading apparatus according to claim 1, wherein the reliability acquisition unit extracts flattened data as the smoothed data. 3. The image reading device according to claim 1, further comprising a notifying unit that notifies information to the outside, wherein the reliability obtaining unit compares the obtained variation with a predetermined value. When the variation is higher than the predetermined value, it is considered that the reliability of the evaluation by the focus detection means is insufficient, and a determination means is provided for instructing the notification means to report the fact. Image reading device. 4. The image reading apparatus according to claim 1, wherein a positional relationship between the document and the optical sensor unit is changed in a direction such that the irradiation area scans the document. Further comprising a scanning mechanism, wherein the reliability obtaining means compares the obtained variation with a predetermined value, and when the variation is higher than the predetermined value, drives the scanning mechanism to irradiate the irradiation on the document. An image reading apparatus, comprising: a determination unit for re-operating the sampling unit after changing a position of an area. 5. A method of irradiating a document with reading light,
An optical sensor unit that detects an optical image formed by light transmitted or reflected by the irradiation area of the reading light on the original; and a focus mechanism that changes a positional relationship between the original and the optical sensor unit in a focus adjustment direction. A control method for the image reading apparatus, wherein a sampling procedure for capturing data of each optical image detected by the optical sensor unit under each of the positional relationships changed by driving the focus mechanism; and a sampling procedure for capturing data in the sampling procedure. A focus detection procedure for evaluating a focus adjustment state between the original and the optical sensor unit by extracting and comparing contrast data of each optical image from the data of each optical image, and data of each optical image. And extracting the smoothed data of each optical image from A method for acquiring a variation between extracted smoothed data as an index indicating the reliability. 6. The control method for an image reading apparatus according to claim 5, wherein the reliability acquisition step is a step of extracting flattened data as the smoothed data. Method. 7. A control method for an image reading apparatus comprising: the optical sensor unit according to claim 5; and a focus mechanism, and further comprising a notifying unit for notifying information to the outside, wherein the sampling according to claim 5 is performed. The method further comprises: a procedure and a focus detection procedure; and a reliability acquisition procedure according to claim 5 or 6. The reliability acquisition procedure includes: comparing the acquired variation with a predetermined value; An image reading apparatus which, when higher than the predetermined value, considers that the reliability of the evaluation by the focus detection procedure is insufficient, and includes a determination procedure for instructing the notification means to report the fact; Control method for 8. An optical sensor unit and a focus mechanism according to claim 5, wherein a positional relationship between the original and the optical sensor unit is changed in a direction such that the irradiation area scans the original. A control method for an image reading apparatus further comprising a scanning mechanism for causing the image reading apparatus to have a sampling procedure and a focus detection procedure according to claim 5, and a reliability acquisition procedure according to claim 5 or 6, In the reliability acquisition step, the acquired variation is compared with a predetermined value, and when the variation is higher than the predetermined value, the scan mechanism is driven to change the position of the irradiation area on the document. A control procedure for the image reading apparatus, which includes a determination procedure for re-executing the sampling procedure. 9. While irradiating a reading light to a document,
An optical sensor unit for detecting an optical image formed by light transmitted or reflected by the irradiation area of the reading light on the original; and a focus mechanism for changing a positional relationship between the original and the optical sensor unit in a focus adjustment direction. A storage medium storing a control procedure for the image reading apparatus, wherein a sampling procedure for capturing data of each optical image detected by the optical sensor unit under each of the positional relationships changed by driving the focus mechanism; By extracting and comparing contrast data of each optical image from the data of each optical image captured by the sampling procedure and comparing the focus data, a focus detection procedure for evaluating a focus adjustment state between the document and the optical sensor unit, While extracting the smoothed data of each optical image from the optical image data, Wherein as an index indicating the reliability of the evaluation, the image reading storage medium storing a control procedure for the apparatus characterized by storing the reliability obtaining step of obtaining the variation between the smoothed data extracted. 10. The storage medium storing a control procedure for the image reading device according to claim 9, wherein the reliability acquisition step is a step of extracting flattened data as the smoothed data. A storage medium storing a control procedure for the image reading device. 11. A storage medium storing a control procedure for an image reading apparatus, comprising: the optical sensor unit according to claim 9; and a focus mechanism, and further comprising a notifying unit for notifying information to the outside. And storing the sampling procedure and the focus detection procedure according to claim 9, and the reliability acquisition procedure according to claim 9 or 10, wherein the reliability acquisition procedure compares the acquired variation with a predetermined value. If the variation is higher than the predetermined value, a determination procedure is included that considers that the reliability of the evaluation by the focus detection procedure is insufficient and instructs the notification means to notify the user. A storage medium storing a control procedure for the image reading apparatus. 12. An optical sensor unit and a focus mechanism according to claim 9, wherein a positional relationship between said document and said optical sensor unit is changed in a direction such that said document is scanned by said irradiation area. A storage medium storing a control procedure for an image reading apparatus further comprising a scanning mechanism for causing the image reading apparatus to perform a sampling procedure and a focus detection procedure according to claim 9, and a reliability acquisition procedure according to claim 9 or 10. In the reliability obtaining step, the obtained variation is compared with a predetermined value, and when the variation is higher than the predetermined value, the scanning mechanism is driven to drive the irradiation on the document. A control procedure for the image reading apparatus, which includes a determination procedure for re-executing the sampling procedure after changing the position of the area, is described. The storage medium. 13. An optical sensor unit for irradiating a document with reading light, and detecting an optical image formed by light transmitted or reflected in the reading light irradiation area of the document, the document and the optical sensor unit. A data structure for encoding and transmitting a computer program signal including a control procedure for an image reading apparatus having a focus mechanism for changing a positional relationship between the focus mechanism and the focus mechanism. A sampling procedure for capturing data of each optical image detected by the optical sensor unit under each of the positional relationships changed by driving; and extracting contrast data of each optical image from data of each optical image captured by the sampling procedure. Comparing the focus between the original and the optical sensor unit Focus detection procedure for evaluating the knot state, and extracted smoothed data of each optical image from the data of each optical image, and each extracted smoothed data as an index indicating the reliability of the evaluation by the focus detection procedure And a reliability obtaining procedure for obtaining a variation between the two. A data structure for encoding and transmitting a computer program signal.