JP2001116983A - Focus position adjusting device, focus position adjusting method of image reader, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus position adjusting device, a focus position adjusting method of an image reader, and a recording medium with a recorded computer- readable program for actualizing focus position adjustment which make it possible to adjust focus to a position where resolution can be obtained in a well- balanced state over the entire read surface when the focus position is finely adjusted after an optical unit is adjusted and assembled as a device. SOLUTION: The device is equipped a test chart for resolution test which forms a black-and-white line pair pattern, an image read part which reads the image of the test chart set on an image reader as an object of focus position adjustment, a resolution measurement part which measures the resolution of the read image, and an adjustment position determination part which compares the measured resolution with an adjustment standard predetermined by an adjustment standard setting part and feeds the adjustment position back to the image reader to move the focus position of an optical unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus position adjusting technique for an image reading apparatus, and more particularly, to a focus position adjusting apparatus and a focus position of an image reading apparatus which realize adjustment to a focus position at which a resolution can be obtained in a well-balanced manner. The present invention relates to an adjustment method and a recording medium for recording a computer-readable program for realizing focus position adjustment.

[0002]

2. Description of the Related Art In an image reading apparatus, it is necessary to accurately form an image of a read document on an image sensor.
Adjusting the focal position in a balanced manner over the entire reading surface is a very difficult task.

Here, the following terms according to the present invention are defined and clarified.

Main scanning direction: Two-dimensional information on a document
A scanning line direction in which pixels are sequentially read in order to convert them into one-dimensional electric signals. That is, the scanning is performed by electronic scanning of the image sensor itself.

Sub-scanning direction: A scanning direction perpendicular to the main scanning direction.

[0006] Focusing: In optical equipment, an operation of matching a light receiving surface with an image plane with respect to a target object plane. Also called focusing.

Focus position: A set position at which an image of a read document is accurately formed on an image sensor based on a set specific adjustment value in the course of a focusing operation of the image reading apparatus.

Luminance: The amount of light per unit area on the light receiving surface. Furthermore, since the sharpness of an image is judged by the human eye based on the magnitude of the luminance, when combining the component lights decomposed into the red component, the green component, and the blue component, based on the relative luminosity factor of the human, Correct the configuration.

FIG. 8 is a view for explaining the optical unit adjustment. In the figure, adjustment of the optical unit is performed in a process before assembling and assembling the optical unit into the apparatus. The adjustment of the optical unit includes lens position adjustment, focusing, and magnification error in the main scanning direction. In the lens position adjustment, CC in the main scanning direction (X direction)
The center of the D center and the center of the lens are aligned. In focusing, the CCD and the lens are moved in the Y direction so that the image on the reading surface is accurately formed on the CCD. Regarding the magnification error in the main scanning direction, the difference between the distance read by the optical unit and the ideal distance at a predetermined distance in the main scanning direction is set to a standard value or less.

FIG. 9 is an explanatory diagram of a resolution test. In the figure, after assembling the adjusted optical unit into the apparatus, a resolution test is performed. In the resolution test, a test chart for a resolution test that forms a black-and-white line pair pattern is set in an image reading device to be adjusted in focus position, a reading instruction is given to the image reading device, the image is read, and the resolution is read from the read image. Is measured.

As shown in FIG. 1A, the black-and-white line pair pattern formed on the test chart is formed so that the line width is slightly shifted from the pixel, and the pixel is periodically matched with the line width. I have. Further, as shown in FIG. 3B, when the image of the test chart is read and the resolution is measured from the read image, the maximum gradation difference between the red component, the green component, and the blue component is measured.

FIG. 10 is a view for explaining focus adjustment. In the figure, in focus adjustment, the focus line is curved with respect to the reading surface due to field curvature, which is one of lens aberrations. For this reason, it is necessary to move the CCD or the lens in the Y direction and adjust the focal position within the standard value with good balance as a whole.

FIG. 11 shows a schematic flowchart of the prior art. In step S101, the optical unit is adjusted as described with reference to FIG. That is, lens position adjustment, focusing, and magnification error in the main scanning direction are performed. In step S102, the adjusted optical unit is incorporated into the apparatus to form an image reading apparatus.

In step S103, a resolution test is performed as described with reference to FIG. The resolution test uses a test chart for a resolution test that forms a black and white line pair pattern, reads the image, and measures the resolution from the read image.

In step S104, it is determined whether the resolution is within the standard value. If the resolution is within the standard value, the process ends. If not, the process proceeds to step S105.

In step S105, FIG.
The focus position is adjusted as described above. Then, the process returns to step S103. In this step, the operator performs the fine adjustment for adjusting the focal position by visual observation repeatedly.

FIG. 12 shows a flowchart of the prior art. In the figure, the details of the focus position adjustment procedure will be described.

In step S111, a test chart for a resolution test for forming a black and white line pair pattern is read.

In step S112, a measurement area is cut out.

In step S113, all the tone differences between the red, green, and blue components of two adjacent pixels are extracted from the cut out measurement area.

In step S114, the maximum gradation difference between the red, green, and blue components is set as a measured value.

In step S115, the maximum gradation difference between the red, green, and blue components is compared with the allowable values of the red, green, and blue components.

In step S116, it is determined whether or not the maximum gradation difference between the red, green, and blue components is equal to or larger than an allowable value. If the value is equal to or larger than the allowable value, the process ends. If not, the process proceeds to step S117.

In step S117, an image of the cut-out measurement area is displayed and visually confirmed.

In step S118, the EEP of the device
The value of the CCD in the ROM or the Y direction of the lens (see FIGS. 8 and 10) is changed. That is, the CCD or the lens is moved to the Y direction position. And step S111
Return to

[0026]

As described above, the prior art has the following problems.

1) In the adjustment of the focal position, the operation of visually resolving the resolution test and the fine adjustment for adjusting the focal position by the operator is performed repeatedly. Therefore, this kind of work requires a lot of time.

2) In the adjustment of the focal position, the focus line is curved with respect to the reading surface due to the curvature of field, which is one of the lens aberrations. Adjusting the focal position is a difficult task. Therefore, this type of operation requires skill.

It is an object of the present invention to 1) finely adjust the focal position after adjusting the optical unit and assembling it as a device, thereby making it possible to adjust the focal position to obtain a well-balanced resolution over the entire reading surface. It is in.

2) By automatically and finely adjusting the focal position adjustment, it is possible to reduce the time required for this kind of work without requiring any skill.

3) In determining the adjustment position, the focus position is adjusted in consideration of variations in mass production.

4) In the adjustment of the focal position, it is difficult to correlate with the visual perception of human beings because it is difficult to determine whether the maximum gradation difference between the red, green, and blue components is greater than an allowable value. And make adjustments possible.

5) To minimize the number of times the test chart is read by predicting the peak position of the resolution.

6) The purpose of the present invention is to correctly detect a resolution value by excluding dust adhering to a reading surface or a test chart in a resolution test.

[0035]

In order to solve the above problems, the present invention takes the following measures.

The image of the test chart for the resolution test is read by the image reading device for adjusting the focal position, the resolution is measured from the read image, the adjustment position is determined by comparing with the adjustment standard, and fed back to the image reading device. A focus position adjusting device configured to move a focus position is provided.

Further, a test chart for a resolution test for forming a black-and-white line pair pattern is set in an image reading apparatus for focus position adjustment, a reading instruction is given to the image reading apparatus to read the image, and the read image is read. Measuring the resolution, comparing the measured resolution with a predetermined adjustment standard to determine an adjustment position, feeding back the adjustment position to the image reading device, and moving the focus position of the optical unit, A position adjustment method is provided.

Further, the present invention provides a recording medium on which a computer-readable program for realizing the focus position adjusting method of the image reading apparatus is recorded.

By taking the above measures, the optical unit can be adjusted to the focal position where the resolution can be obtained in the best balance.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention adopts the following embodiments.

As shown in FIG. 1, the focus position adjusting device 1
Is a test chart 2 for a resolution test for forming a black-and-white line pair pattern, an image reading unit 5 for reading an image of the test chart 2 set on the image reading device 3 for focus position adjustment, and a resolution from the read image. The resolution measuring unit 6 to be measured, the measured resolution is compared with an adjustment standard previously set by the adjustment standard setting unit 8 to determine an adjustment position, and the adjustment position is fed back to the image reading device 3 to focus the optical unit 4 on the focus. And an adjustment position determination unit 7 for moving the position.

Further, as shown in FIG. 3, the adjustment standard setting section 8 sets an adjustment standard which is a high value obtained by adding a predetermined margin to the normal standard which is a normal resolution standard.

Further, as shown in FIG. 3, the adjustment position determination section 7 measures the resolution at a plurality of locations in the main scanning direction and / or the resolution at a plurality of locations in the sub-scanning direction in determining the adjustment position. Feedback the adjustment position to the image reading device.

Further, the adjustment position determination unit 7 converts the values of the red, green, and blue components of each pixel into luminance in the adjustment position determination, and adjusts the luminance based on the luminance.

Further, as shown in FIG. 4, the adjustment position determination section 7 predicts the peak position of the resolution from the value of the resolution at the time of moving the focal position in the determination of the adjustment position.

Further, as shown in FIG. 5, the resolution measuring section 6 performs the measurement while excluding dust adhering to the reading surface and the test chart in the resolution measurement.

In the method of adjusting the focal position of the image reading apparatus, a test chart for a resolution test for forming a black-and-white line pair pattern is set in the image reading apparatus to be adjusted for the focal position, and a reading instruction is issued to the image reading apparatus. The read image is read, the resolution is measured from the read image, the measured resolution is compared with a predetermined adjustment standard to determine an adjustment position, and the adjustment position is fed back to the image reading device to return the focus of the optical unit. Move position.

Further, in the above-mentioned method of adjusting the focal position of the image reading apparatus, when the adjustment position is determined, the measured resolution is a high value obtained by adding a predetermined margin to the normal standard which is the normal resolution standard. Judge whether it is above the standard value.

Further, in the method of adjusting the focal position of the image reading apparatus, when determining the adjustment position, when the measured resolution is equal to or less than the adjustment standard value, the focus position is adjusted to a position where the shortage with respect to the adjustment standard value is minimized. Then, it is determined whether the value is equal to or larger than the normal specification value.

Further, in the method of adjusting the focal position of the image reading apparatus, the resolution at a plurality of locations in the main scanning direction and / or the resolution at a plurality of locations in the sub-scanning direction are measured in determining the adjustment position, and the measured resolution is determined in advance. The adjustment position is determined by comparing with the adjusted adjustment standard, and the adjustment position is fed back to the image reading device.

Further, in the above-mentioned method of adjusting the focal position of the image reading apparatus, in determining the adjustment position, the values of the red, green and blue components of each pixel are converted into luminance, and the converted luminance is adjusted to a predetermined adjustment standard. To determine the adjustment position.

Further, in the method of adjusting the focal position of the image reading apparatus, the peak position of the resolution is predicted from the value of the resolution when the focal position is moved in determining the adjustment position, and the position of the optical unit to be moved next is obtained. .

Further, in the method of adjusting the focal position of the image reading apparatus, when adjacent gradation differences do not fall within a specified value range during waveform analysis in resolution measurement, they are excluded from measurement data.

The recording medium on which the program for adjusting the focal position of the image reading apparatus is recorded has a computer read a test chart for a resolution test for forming a black and white line pair pattern by the image reading apparatus to be adjusted for the focal position. The procedure, the procedure for measuring the resolution from the read image, the measured resolution is compared with a predetermined adjustment standard to determine the adjustment position, and the adjustment position is fed back to the image reading device to set the focal position of the optical unit. Record a computer readable program for executing the moving procedure. In addition, this program
This is stored in various appropriate recording media such as FD and CD for recording.

By taking the above embodiment, the following operation works.

A test chart for a resolution test is set on the image reading device to be adjusted for the focal position, the image is read, the resolution is measured from the read image, and the measured resolution is compared with the adjustment standard to determine the adjustment position. Then, by feeding back to the image reading device and moving the focal position, the focal position is adjusted to obtain the most balanced resolution.

Further, by providing an adjustment standard having a high value obtained by adding a predetermined margin to the normal standard, which is a normal resolution standard, the focus position is adjusted in consideration of variation in mass production in determining the adjustment position. Further, when determining the adjustment position, when the measured resolution is equal to or less than the adjustment standard value, determine the position where the shortfall with respect to the adjustment standard value is the minimum, and determine whether the normal standard value or more, Focus position adjustment is performed in a well-balanced manner with respect to normal standards.

Further, in determining the adjustment position, the resolution at a plurality of locations in the main scanning direction and / or the resolution at a plurality of locations in the sub-scanning direction are measured, and the adjustment position is fed back to the image reading device from these results, thereby achieving a good balance. Adjust the focus position.

Further, in determining the adjustment position, the values of the red component, the green component, and the blue component of each pixel are converted into luminance and adjusted by the luminance, so that the focal position is adjusted to a value close to visual observation.

Furthermore, the number of times of reading the test chart is reduced as much as possible by predicting the peak position of the resolution from the value of the resolution when the focal position is moved in the adjustment position determination.

Further, in the resolution measurement, the dust attached to the reading surface and the test chart is excluded and the measurement is performed to determine the dust, and the portion is excluded from the measurement data, so that the value of the resolution is correctly detected.

Further, the present invention can be realized by using a program for operating a computer.
Since it can be stored in various suitable recording media such as FDs and CDs for recording, it can be installed in any processing device and processed when necessary.

[0063]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A representative embodiment according to the present invention will be described with reference to FIGS. In the following, the same portions are denoted by the same reference numerals, and detailed description may be omitted.

FIG. 1 shows a configuration diagram of the present invention.

In the figure, a focus position adjusting device 1 includes a test chart 2 for a resolution test and an image reading device 3 to which a focus position is to be adjusted by incorporating an adjusted optical unit 4.
, An image reading unit 5, a resolution measuring unit 6, an adjustment position determining unit 7, and an adjustment standard setting unit 8.

The test chart 2 forms the black-and-white line pair pattern shown in FIG. 9 described above. The black-and-white line pair pattern is formed so that the line width is slightly shifted from the pixel, and the pixel is periodically shifted from the line width. To match. The image reading section 5 reads an image of the test chart 2 set on the image reading device 3. The resolution measuring section 6 measures the resolution from the read image of the test chart 2. In this case, the maximum gradation difference between the red, green, and blue components is measured.

The adjustment position determination unit 7 determines an adjustment position by comparing the resolution measured by the resolution measurement unit 6 with a predetermined adjustment standard, and feeds back the adjustment position to the image reading device 3 to feed the optical unit 4. To move the focal position of. The adjustment standard setting unit 8 sets the adjustment standard.

The details of the resolution measuring section 6, the adjusting position determining section 7 and the adjusting standard setting section 8 will be described later.

FIG. 2 shows a schematic flowchart of the present invention. Note that the reference numerals refer to FIG.

In step S01, the optical unit 4 is adjusted as described with reference to FIG. That is,
Lens position adjustment, focusing, and magnification error in the main scanning direction are performed.

In step S02, the adjusted optical unit 4 is incorporated in the apparatus to constitute the image reading apparatus 3.

In step S03, a resolution test is performed as described with reference to FIG. The resolution test uses a test chart 2 for a resolution test that forms a black-and-white line pair pattern. The image reading unit 5 reads the image, and the resolution measuring unit 6 measures the resolution from the read image.

In step S04, the adjustment position determination unit 7 compares the measured resolution with the adjustment standard previously determined by the adjustment standard setting unit 8 to determine whether the resolution is within the adjustment standard value. The process ends. If not, the process proceeds to step S05.

In step S05, the adjustment position determination unit 7 determines the adjustment position, feeds back the adjustment position to the image reading device 3, moves the focal position of the optical unit 4, and returns to step S03. That is, the adjustment position determination unit 7 performs the automatic focus position adjustment by finely adjusting the focus position of the optical unit 4.

Next, details of the resolution measuring unit 6, the adjustment position determining unit 7, and the adjustment standard setting unit 8 will be described.

FIG. 3 is an explanatory view of an embodiment of the present invention.

The adjustment standard setting section 8 has an adjustment standard and a normal standard, and the adjustment standard has a high value obtained by adding a margin to the normal standard. As a result, it is possible to adjust the focus position in consideration of variations in mass production in determining the adjustment position. The normal standard is a normal resolution standard that can be used as a shipping standard when shipping the device.

Next, the adjustment position determination will be described.
3A, the main scanning direction will be described. The resolution measurement in the main scanning direction is performed by taking into account the imbalance in the main scanning direction due to the curvature of field of the lens, for example, with the red component of each pixel at the central portion in the main scanning direction, right side, and left side. Measure the value of the green component and the blue component and measure the maximum gradation difference, and find the curve of the margin shortage total value that is the sum of the shortage to the adjustment standard value at the center, right side, and left side, and adjust The position where the total value of the shortage with respect to the standard value becomes the minimum is the position where the focal position of the optical unit 4 is moved.

The sub-scanning direction will be described with reference to FIG. The resolution measurement in the sub-scanning direction is performed by taking into account the imbalance in the sub-scanning direction due to the curvature of field of the lens and the like, and for example, the red component and the green component of each pixel at the central portion, right side, and left side. Measure the value of the blue component and measure the maximum gradation difference, find the curve of the margin shortage total value that is the sum of the shortage for the adjustment standard value at the center, the right side, and the left side, and calculate the curve for the adjustment standard value. The position where the total value of the shortage becomes minimum is the position where the focal position of the optical unit 4 is moved.

Referring to FIG. 3C, the main scanning direction and the sub-scanning direction will be described. FIG. 3A and FIG.
A curve of the total shortage of the main scanning and sub-scanning margins obtained by adding the curve of the total shortage of the margins in the main scanning direction obtained in (b) and the curve of the total shortage of the margins in the sub-scanning direction is obtained and adjusted. The position where the total value of the shortage with respect to the standard value becomes the minimum is determined as the position where the focal position of the optical unit 4 is moved. Thereby, the focus position can be adjusted in a well-balanced manner including the main scanning direction and the sub-scanning direction.

In the adjustment position determination, the values of the red, green, and blue components of each pixel are converted into luminance, and the converted luminance is compared with a predetermined adjustment standard to determine the adjustment position. As a result, it is possible to adjust the focal position with a value close to visual observation.

FIG. 4 is an explanatory view of an embodiment of the present invention.

The adjustment position determining section 7 predicts the peak position of the resolution from the value of the resolution at the time of moving the focal position in the determination of the adjustment position. That is, in FIG. 4A, when the moving order in the Y direction (see FIGS. 8 and 10) in the focus position adjustment is moved from to the end, the margin shortage curve shown in FIG. It has been found that the curve forms a recess on the side. For this reason,
As shown in FIG. 4B, the next position to be moved is between and. Further, as shown in FIG. 4C, the next position to be moved is between and.

As described above, the peak position of the resolution is predicted from the value of the resolution when the focal position is moved in the determination of the adjustment position, and the focal position of the optical unit to be moved next is obtained. In short, the total value of the margin shortage obtained by one measurement is plotted, and unnecessary portions are excluded from the entire graph. Thereby, the number of times of reading the test chart can be reduced as much as possible.

FIG. 5 is an explanatory view of an embodiment of the present invention.

FIG. 5A shows a test chart reading waveform when the above-described test chart is read when no dust or the like adheres to the reading surface and the test chart. That is, the black-and-white line pair pattern formed on the test chart is formed such that the line width is slightly shifted from the pixel, and the pixel periodically matches the line width. Further, in the case of the main scanning, the change of the gradation when viewed in the horizontal direction is such that a high gradation and a low gradation are alternately repeated.

Parts A and B shown in FIGS. 5B and 5C show test chart reading waveforms indicating a decrease in white level due to dust. Further, a portion C shown in FIG. 5D shows a test chart reading waveform indicating a decrease in black level due to dust.

The resolution measuring section 6 measures in the resolution measurement except dust adhering to the reading surface and the test chart shown in FIGS. 5B to 5D. In other words, when adjacent gradation differences do not fall within the range of the specified value during the waveform analysis in the resolution measurement, they are excluded from the measurement data. The determination as to whether or not the adjacent tone difference is within the range of the specified value confirms that the tone change is alternately repeated. In addition, it is confirmed that there is no large difference in the amount of gradation change from the surroundings. Note that the allowable value of the gradation change amount with respect to the surroundings is appropriately set from outside.
As a result, dust is determined and the portion is excluded from the measurement data, so that the value of the resolution can be correctly detected.

Next, the procedure for adjusting the focal position of the image reading apparatus will be described.

FIG. 6 is a block diagram showing an embodiment of the present invention.

In the figure, to adjust the focal position of the image reading apparatus, a test chart 12 for a resolution test for forming the above-described black and white line pair pattern, an image reading apparatus 13 for which the focal position is to be adjusted, and a measuring apparatus 21.

The image reading device 13 is operated by the arithmetic and control unit 19 based on an instruction from the measuring device 21 to control the light source lamp 1.
4. While controlling the operation of the optical unit 15 constituting the CCD 16 and the lens 17, and the operation of the reading moving unit 18,
The read image data of the test chart 12 is measured by the measuring device 2
Transfer to 1. In addition, the arithmetic control unit 19 includes a measuring device 21
8 in the Y direction (FIG. 8)
(See FIG. 10) to adjust the focal position of the optical unit 15.

The measuring device 21 is controlled by the arithmetic and control unit 28 and exchanges data with the image reading device 13 via the driver program 22. The arithmetic control unit 28 causes the control program 23 to process the received image data. Further, the arithmetic control unit 28 obtains a curve of, for example, the total value of the main scanning and sub-scanning margin shortage necessary for adjusting the focal position of the image reading apparatus based on the result processed by the control program 23, and obtains a curve for the adjustment standard value. The position where the total value of the minute is minimum is determined as the position for moving the focal position of the optical unit 15, and the driver program 22
Is transferred to the image reading device 13 via the.

The display unit 26 displays the result of data necessary for adjusting the focal position of the image reading device. Further, the storage unit 27 stores data of a result of the focus position adjustment of the image reading device and the like.

The control program 23 includes a data analysis unit 24
And a determination unit 25. The data analysis unit 24 includes a floor area of two pixels adjacent to each other in the read image of the entire area of the image data in which only a necessary portion of the image data read by the image reading device 13 is cut out. All the differences are extracted, and the maximum gradation difference is calculated to be a measured value. Further, the maximum gradation difference is converted into luminance. The determination unit 25 compares the maximum gradation difference converted into luminance with the extracted adjustment standard value. If the maximum gradation difference is equal to or greater than the adjustment standard value, the focus position of the image reading device is determined to be acceptable, and When the gradation difference is equal to or smaller than the adjustment standard value, the arithmetic control unit 28 is notified.

FIG. 7 shows a flowchart of the present invention. The reference numerals refer to FIG.

In step S11, the arithmetic control unit 19 of the image reading device 13 reads the test chart 12 for the resolution test forming the black and white line pair pattern, and transfers the read image to the measuring device 21.

In step S12, the arithmetic and control unit 28 of the measuring device 21 cuts out the measurement area.

In step S13, the data analysis unit 2
Reference numeral 4 extracts all the gradation differences between the red, green, and blue components of two adjacent pixels in the cut out measurement area.

In step S14, the data analysis unit 2
Reference numeral 4 designates a maximum gradation difference between a red component, a green component, and a blue component as a measured value. At this time, as shown in FIG. 5 described above, when the adjacent gradation difference does not fall within the range of the specified value during the waveform analysis in the resolution measurement, it is excluded from the measurement data.

In step S15, the data analysis unit 2
No. 4 converts the maximum gradation difference into luminance.

In step S16, the determination section 25
A predetermined adjustment standard value is extracted, and the maximum gradation difference converted into luminance is compared with the adjustment standard value.

In step S17, the determination section 25
It is determined whether the maximum gradation difference is equal to or larger than the adjustment standard value. If the maximum gradation difference is equal to or larger than the adjustment standard value, the focus position of the image reading device is determined to be acceptable and the process ends. If the maximum gradation difference is equal to or smaller than the adjustment standard value, the process proceeds to step S18.

In step S18, the arithmetic control unit 28
Indicates that the CCD and the lens this time are in the Y direction (FIG. 8 or FIG. 1).
0) is found for the adjustment standard value at the position moved to (0). For example, as shown in FIG.
A margin shortage total value is obtained by summing up the shortfalls with respect to the adjusted standard values at the three places of the right side and the left side.

In step S19, the data analysis unit 2
No. 4 determines whether the entire adjustment range of the optical unit 15 in the Y direction has been performed. If all have been performed, step S2
Go to 0. If not all have been performed, step S24
Proceed to.

In step S24, the operation control unit 2
Step 8 finds the position in the Y direction between the CCD and the lens that will move next time. At this time, as shown in FIG. 4, the peak position of the resolution is predicted from the value of the resolution at the time of moving the focal position, and the focal position of the optical unit that moves next is obtained. Then, the process returns to step S11.

In step S20, the arithmetic control unit 28
Determines the position where the total value of the margin shortage with respect to the adjustment standard value in step S18 becomes the minimum as the position for moving the focal position of the optical unit 15, and transfers it to the image reading device 13 via the driver program 22. . In addition, the arithmetic control unit 19 adjusts the focal position of the optical unit 15 by moving the CCD 16 and the lens 17 in the Y direction (see FIG. 8 or 10) based on an instruction from the measuring device 21.

In step S21, the measuring device 21
Performs a resolution test of the image reading device 13 whose focal position has been adjusted.

In step S22, the judgment section 25
It is determined whether or not the maximum gradation difference is equal to or larger than the normal specification value. If the maximum gradation difference is equal to or larger than the standard value, the focus position of the image reading device is determined to be acceptable and the process is terminated. If the maximum gradation difference is equal to or smaller than the normal specification value, the process is ended in a failure in step S23.

[0110]

As described above, according to the present invention, the following effects can be expected.

A test chart for a resolution test is set on the image reading device to be adjusted for the focal position, the image is read, the resolution is measured from the read image, the adjustment position is determined by comparing with the adjustment standard, and the image reading device is determined. The focal position is adjusted by feeding back to the focal position to obtain the most balanced resolution. Further, the quality can be stabilized by incorporating the optical unit into the image reading apparatus and finally adjusting the focal position finely. Further, by automating the focus position adjustment, the number of assembling and testing steps can be reduced.

Further, by providing an adjustment standard having a high value obtained by adding a predetermined margin to the normal standard which is a normal resolution standard, the focus position can be adjusted in consideration of the variation in mass production in determining the adjustment position. Can be. Further, when determining the adjustment position, when the measured resolution is equal to or less than the adjustment standard value, determine the position where the shortfall with respect to the adjustment standard value is the minimum, and determine whether the normal standard value or more, Focus position adjustment can be performed in a well-balanced manner with respect to normal standards.

Further, in determining the adjustment position, the resolution at a plurality of locations in the main scanning direction and / or the resolution at a plurality of locations in the sub-scanning direction are measured, and the adjustment position is fed back to the image reading device from these results to achieve a good balance. Focus position can be adjusted.

Further, in the adjustment position determination, the values of the red, green, and blue components of each pixel are converted into luminance and adjusted by the luminance, so that the focal position can be adjusted to a value close to visual observation.

Further, by predicting the peak position of the resolution from the value of the resolution when the focal position is moved in the determination of the adjustment position, the number of times of reading the test chart can be reduced as much as possible.

Further, in the resolution measurement, by removing dust adhering to the reading surface and the test chart, the dust is determined, and the portion is excluded from the measurement data, so that the value of the resolution can be correctly detected. it can.

Furthermore, the present invention can be realized by using a program for operating a computer.
Since it can be stored in various suitable recording media such as FDs and CDs for recording, it can be installed in any processing device and processed when necessary.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a schematic flowchart of the present invention.

FIG. 3 is an explanatory diagram of an embodiment of the present invention.

FIG. 4 is an explanatory diagram of an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an embodiment of the present invention.

FIG. 6 is a configuration diagram of an embodiment of the present invention.

FIG. 7 is a flowchart of an embodiment of the present invention.

FIG. 8 is an explanatory diagram of optical unit adjustment.

FIG. 9 is an explanatory diagram of a resolution test.

FIG. 10 is an explanatory diagram of focus adjustment.

FIG. 11 is a schematic flowchart of a conventional technique.

FIG. 12 is a flowchart of a conventional technique.

[Explanation of symbols]

 1: Focus position adjusting device 2: Test chart 3: Image reading device 4: Optical unit 5: Image reading unit 6: Resolution measuring unit 7: Adjustment position determining unit 8: Adjustment standard setting unit 12: Test chart 13: Image reading device 14: Light source lamp 15: Optical unit 16: CCD 17: Lens 18: Reading and moving unit 19: Operation control unit 21: Measurement device 22: Driver program 23: Control program 24: Data analysis unit 25: Judgment unit 26: Display unit 27 : Storage unit 28: Operation control unit

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H051 AA15 BA72 5B047 BB02 BC05 CA11 CA17 CB10 CB30 5C051 AA01 BA02 DB22 DE22 5C062 AB05 AB17 AC58 AD01 5C072 AA01 BA02 BA05 BA16 DA02 RA11 RA18 UA18

Claims (14)

[Claims] 1. A test chart for a resolution test for forming a black-and-white line pair pattern, an image reading section for reading an image of the test chart set in an image reading apparatus for focus position adjustment, and measuring a resolution from the read image The resolution measuring unit to be compared, the measured resolution is compared with an adjustment standard previously set by the adjustment standard setting unit to determine an adjustment position, and the adjustment position is fed back to the image reading device to move the focus position of the optical unit. A focus position adjustment device, comprising: an adjustment position determination unit. 2. The focus position according to claim 1, wherein the adjustment standard setting unit sets an adjustment standard having a high value obtained by adding a predetermined margin to a normal standard that is a normal resolution standard. Adjustment device. 3. The adjustment position determination unit measures the resolution at a plurality of locations in the main scanning direction and / or the resolution at a plurality of locations in the sub-scanning direction in determining the adjustment position,
The focal position adjusting device according to claim 1, wherein the adjustment position is fed back to the image reading device based on these results. 4. The apparatus according to claim 1, wherein the adjustment position determination unit converts the values of the red component, the green component, and the blue component of each pixel into luminance in the adjustment position determination and adjusts the luminance based on the luminance. Focus position adjustment device. 5. The focus position adjusting device according to claim 1, wherein the adjustment position determining unit predicts a peak position of the resolution from a value of the resolution when the focus position is moved in the adjustment position determination. . 6. The focus position adjusting device according to claim 1, wherein the resolution measuring section performs the measurement while excluding dust adhering to the reading surface and the test chart in the resolution measurement. 7. A test chart for a resolution test for forming a black-and-white line pair pattern is set in an image reading device to be adjusted in focus position, a reading instruction is given to the image reading device to read the image, and the read image is read. Measuring the resolution, determining the adjustment position by comparing the measured resolution with a predetermined adjustment standard, and moving the focal position of the optical unit by feeding back the adjustment position to the image reading device; A method for adjusting the focal position of an image reading device. 8. The method of adjusting a focal position of an image reading apparatus according to claim 1, wherein, when determining the adjustment position, the measured resolution is a high value obtained by adding a predetermined margin to a normal standard which is a normal resolution standard. The method according to claim 7, wherein it is determined whether the value is equal to or greater than a standard value. 9. A method of adjusting a focal position of an image reading apparatus, comprising the steps of: determining an adjustment position when a measured resolution is equal to or less than the adjustment standard value; 9. The method according to claim 8, further comprising: determining whether the value is equal to or greater than the normal standard value. 10. A method for adjusting a focal position of an image reading apparatus, comprising: measuring resolutions at a plurality of positions in a main scanning direction and / or resolutions at a plurality of positions in a sub-scanning direction in determining an adjustment position; 10. The focus position adjusting method for an image reading device according to claim 7, wherein the adjustment position is determined by comparing the adjustment position with the adjustment standard, and the adjustment position is fed back to the image reading device. 11. A method for adjusting a focal position of an image reading apparatus, comprising the steps of: converting a value of a red component, a green component, and a blue component of each pixel into luminance in determining an adjustment position; 11. The focus position adjusting method for an image reading apparatus according to claim 7, wherein the adjustment position is determined by comparing the adjustment position. 12. The method of adjusting a focal position of an image reading apparatus according to claim 1, wherein a peak position of the resolution is predicted from a value of the resolution when the focal position is moved in determining the adjustment position, and a position of the optical unit to be moved next is obtained. The focus position adjusting method for an image reading apparatus according to claim 7, wherein: 13. The method of adjusting the focal position of the image reading apparatus according to claim 1, wherein when a waveform difference in a resolution measurement does not include an adjacent gradation difference within a specified value range, the difference is excluded from the measurement data. A method for adjusting a focal position of an image reading apparatus according to claim 7. 14. A computer comprising: a computer for reading a test chart for a resolution test for forming a black-and-white line pair pattern by an image reading apparatus for focus position adjustment; a procedure for measuring a resolution from a read image; A computer-readable program for executing a procedure of determining an adjustment position by comparing with a predetermined adjustment standard, feeding back the adjustment position to the image reading device and moving the focal position of the optical unit, recoding media.