JP2008067275A - Image reader, and method of adjusting power and focus of imaging lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of easily adjusting power and focus with high precision, and a method of adjusting the power and focus of an imaging lens. <P>SOLUTION: The image reader includes, in an integrated scanning optical system unit, a light source means of lighting a document, a plurality of mirrors to reflect luminous flux from the document lit by the light source means, the imaging lens imaging the luminous flux reflected by the plurality of mirrors, and a photoelectric converting element to receive and convert the light imaged by the imaging lens into an electric signal, and also has a means of enabling the imaging lens to move a plate mounted with the photoelectric converting element along an optical axis, and an abutting means of installing the plate mounted with the imaging lens and photoelectric converting element in the integrated scanning optical system unit at one of a plurality of positions in the optical-axis direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and a method for adjusting the magnification and focus of an imaging lens. In particular, an image reading apparatus such as an image scanner or a digital copying machine which reads image information of an original using a light source means, a plurality of mirrors, an imaging optical system, and a reading means (photoelectric conversion element such as a line sensor). It is suitable for.

  Various image reading apparatuses such as image scanners and digital copying machines have been proposed.

  FIG. 9 is a schematic diagram of a main part showing the configuration of a conventional image reading apparatus.

  In the figure, reference numeral 502 denotes an original table (original table glass) on which an original 501 is placed.

  Reference numeral 503 denotes light source means, which is composed of a xenon tube, a halogen lamp, an LED array, or the like. Reference numerals 504 a, 504 b, 504 c, and 504 d are reflection mirrors, respectively, and bend the light beam from the original 501 inside the carriage 507. Reference numeral 506 denotes an imaging lens (imaging optical system) that focuses a light beam based on image information of the original 501 on the surface of the reading unit 505. Reference numeral 505 denotes a photoelectric conversion element (hereinafter referred to as “CCD”) that receives light imaged by an imaging lens such as a line sensor as a reading means and converts it into an electrical signal, which is perpendicular to the paper surface. It has a configuration in which a plurality of pixels (light receiving elements) are arranged in the main scanning direction.

  Reference numeral 507 denotes a carriage, which integrally houses a light source unit 503, a plurality of reflection mirrors 504a, 504b, 504c, and 504d, an imaging lens 506, a reading unit 505, and the like. The carriage 507 is scanned in the direction of arrow A (sub-scanning direction) in the figure by a driving device 508 such as a motor, and reads image information of the original 501. The read image information is sent to an external device such as a personal computer through an interface (not shown).

  In such an image reading apparatus, adjustment is performed in the manufacturing process so that the magnification and focus of the imaging lens 506 with respect to the CCD 505 conform to the specifications of the image reading apparatus. As this adjustment method, adjustment is performed based on the result of light reception by the CCD 505 of light passing through the mirrors 504a to 504d and the imaging lens 506. For example, the magnification adjustment is performed by moving the imaging lens 506 in the optical axis direction in order to expand or contract the optical path length from the document 501 to the imaging lens 506. On the other hand, the focus adjustment is performed by moving the CCD 505 in the optical axis direction in order to expand or contract the optical path length from the imaging lens 506 to the CCD 505.

  Here, an example of an adjustment procedure for moving the imaging lens 506 and the CCD 505 will be described with reference to FIG. FIG. 10 is a flowchart showing a conventional method for adjusting the magnification and focus of the imaging lens in the manufacturing process of the image reading apparatus.

  First, in step S1, the imaging lens and the CCD are set at standard positions. At this stage, the imaging lens and the CCD can move in the optical axis direction independently of each other. In step S2, the CCD is first moved by a specific amount. Thereafter, in step S3, the magnification and focus are detected by the CCD. In other words, here, the original having the image surface of the test pattern is irradiated with light from the light source means, and the reflected light from the original passes through the mirror and the imaging lens to reach the CCD. Magnification and focus are detected.

  Subsequently, in step S4, it is determined whether or not the magnification and focus are within standard values corresponding to the specifications of the image reading apparatus. If both are within the standard value, the adjustment ends in step S6. On the other hand, if any of the values is out of the standard value, the process proceeds to step S5, where the moving amount of the imaging lens is calculated based on the deviation amount of the magnification with respect to the standard value, and the imaging lens is moved by the moving amount. The And it returns to step S2 and said operation | movement is repeated.

  However, with regard to the movement of the CCD in the repeated steps, that is, the second and subsequent times (step S2), if only the focus is within the standard value, the CCD is connected to maintain the optical path length from the imaging lens to the CCD. The image lens is moved by the same amount in the same direction in which the image lens is moved. If the focus is out of the standard value, the CCD is moved in consideration of the movement amount of the CCD calculated based on the focus shift amount with respect to the standard value.

  However, in the above adjustment method, it is difficult to converge both the magnification and the focus within an allowable range unless the adjustment of the lens position and the focus is repeated many times. Various methods for adjusting an image reading apparatus that have solved this problem have been proposed (see Patent Document 1).

In Patent Document 1, the magnification of the imaging lens is measured in advance, and the working time is shortened by grouping.
JP 2004-260370 A

  However, in Patent Document 1, when adjusting the positions of the imaging lens and the CCD, the CCD is attached to a plate different from the plate to which the imaging lens is attached. There was a problem with the inclination in the scanning direction. Further, since the number of parts to be configured increases, there is a problem that the entire apparatus becomes complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus and an imaging lens magnification and focus adjustment method capable of easily and accurately adjusting the magnification and focus of the imaging lens.

The image reading apparatus of the invention of claim 1
A light source means for illuminating the original; a plurality of mirrors for reflecting the light flux from the original illuminated by the light source means; an imaging lens for imaging the light flux reflected by the plurality of mirrors; and the imaging lens. An image reading device provided in an integrated scanning optical system unit with a photoelectric conversion element that receives the formed light and converts it into an electrical signal,
Movable means for allowing the imaging lens to move in the optical axis direction on a plate on which the photoelectric conversion element is mounted;
Abutting means for setting the plate on which the imaging lens and the photoelectric conversion element are placed at one of a plurality of positions in the optical axis direction on the integrated scanning optical system unit; It is characterized by that.

The magnification and focus adjustment method of the imaging lens of the invention of claim 2
A light source means for illuminating the original; a plurality of mirrors for reflecting the light flux from the original illuminated by the light source means; an imaging lens for imaging the light flux reflected by the plurality of mirrors; and the imaging lens. A method of adjusting the magnification and focus of the imaging lens in an image reading apparatus provided with an integrated scanning optical system unit that receives a formed light and converts it into an electrical signal,
Based on the measurement result of the magnification measurement of the imaging lens at the one position among a plurality of positions in the optical axis direction on the integrated scanning optical system unit with the plate on which the imaging lens and the photoelectric conversion element are mounted. A magnification adjusting step for adjusting the magnification of the imaging lens by installing using the abutting means;
A focus adjustment step for adjusting the focus by moving the imaging lens on the plate in the optical axis direction after the magnification adjustment step;
It is characterized by having.

The invention of claim 3 is the invention of claim 2,
The image forming lens further includes a classification step of previously classifying the image forming lens into the same number as the plurality of positions in the optical axis direction of the image forming lens set by the abutting unit based on the magnification measurement result. Yes.

The invention of claim 4 is the invention of claim 2 or 3, wherein
The focus adjustment step is performed by referring to the contrast of document information obtained from the photoelectric conversion element.

The invention of claim 5 is the invention of claim 2 or 3, wherein
The focus adjustment step includes an image height position symmetrical to the optical axis at the maximum image height of 50% or more of the maximum image height on the optical axis of the imaging lens and in the main scanning direction from the original information obtained from the photoelectric conversion element. This is characterized by referring to the contrast of document information in

  According to the present invention, it is possible to achieve an image reading apparatus and an image forming lens magnification and focus adjustment method that can easily and accurately adjust the magnification and focus of the imaging lens.

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

  FIG. 1 is a schematic diagram of a main part when the first embodiment of the present invention is applied to an image reading apparatus of an image scanner. FIG. 2 is a perspective view of essential parts around the imaging lens and the CCD shown in FIG. FIG. 3 is a perspective view of a main part of the plate on which the imaging lens and the CCD shown in FIG. 2 are attached. 4A and 4B are explanatory diagrams showing examples of groups selected according to magnification errors with respect to the prescribed magnification of the imaging lens of Embodiment 1 of the present invention. FIG. 5 is an explanatory diagram showing the image height position (image reading position) of the adjustment chart according to the first embodiment of the present invention. FIG. 6 is a flowchart showing the adjustment procedure of the first embodiment of the present invention.

  First, each element constituting the image reading apparatus shown in FIG. 1 will be described.

  In the figure, reference numeral 1 denotes an image reading apparatus main body, and reference numeral 102 denotes a document table (document table glass). A document 101 is placed on the surface of the document table 102.

  Reference numeral 103 denotes a light source means for illuminating the document, which is composed of a xenon tube, a halogen lamp, an LED array, or the like. The light source means 103 may be used in combination with a reflector such as an aluminum vapor deposition plate. Reference numerals 104a, 104b, 104c, and 104d denote first, second, third, and fourth mirrors, respectively, that fold the light beam from the original 101 inside the carriage 107. Reference numeral 106 denotes an imaging lens (imaging optical system) that focuses a light beam based on image information of the original 101 on the surface of the reading means 105. Reference numeral 105 denotes a photoelectric conversion element (hereinafter referred to as “CCD”) such as a line sensor serving as a reading unit, which has a configuration in which a plurality of pixels (light receiving elements) are arranged in a main scanning direction that is perpendicular to the paper surface. Yes.

  Reference numeral 107 denotes an integrated scanning optical system unit which integrally houses the light source means 103, a plurality of scanning mirrors 104a to 104d, the imaging lens 106, the reading means 105, and the like. The integrated scanning optical system unit 107 is also referred to as “carriage” hereinafter.

  The carriage 107 scans the image information of the document 101 by scanning in the direction of arrow A (sub-scanning direction) in the figure by a driving device 108 such as a motor. The read image information is sent to an external device such as a personal computer through an interface (not shown). Note that the image information of the document 101 may be read by relatively moving the carriage 107 and the document 101.

  Next, the configuration around the imaging lens 106 and the CCD 105 will be described with reference to FIGS.

  The imaging lens 106 is temporarily fixed to a plate 201 made of a highly rigid metal plate so as to be movable in the optical axis direction by temporary fixing means including a spring and a bolt.

  The plate 201 is attached to the carriage 107 at one of a plurality of positions in the optical axis direction with bolts or the like. The CCD 105 is also fixed to the same plate 201.

  By attaching the imaging lens 106 and the CCD 105 to the same plate 201, since the same member is used, there is no backlash when attaching the CCD 105 because it is the same member, so the accuracy is improved. In addition, since the number of parts is reduced, the entire apparatus can be simplified.

  When the plate 201 is fixed to the carriage 107, in the manufacturing process of the image reading apparatus main body 1, the plate 201 is adjusted in the optical axis direction so as to meet the specifications, and then is definitely attached with a bolt or the like. This adjustment in the optical axis direction is achieved by abutting means comprising a long hole 202 formed in the plate 201 and a support pin 203 formed in the carriage 107. It is done by hitting.

  As for the abutting direction, as shown in FIGS. 4A and 4B, the imaging lens grouped based on the result of measuring the magnification of the imaging lens (that is, measuring the focal length) is applied to the plate 201. The direction of abutment is known for mounting.

  In the present embodiment, there are two places before or after the optical axis direction, so the grouping is divided into two ways of A and B as shown in FIG. For example, if the imaging lens 106 mounted on the plate 201 is the A group shown in FIG. 4A, the plate 201 is abutted against the rear side in the optical axis direction. In the case of the B group, the plate 201 is abutted against the front side in the optical axis direction. This makes it possible to make adjustments that meet the magnification specifications in a short time.

  Next, a method for fixing the imaging lens 106 will be described.

  The imaging lens 106 is fixed by adjusting the imaging lens 106 in the optical axis direction so as to meet the specifications in the manufacturing process of the image reading apparatus main body 1 in the same manner as the plate 201 process, and then temporarily stopping the fixing. It is attached to the plate 201 with a spring and a bolt. In this adjustment, the output result of the contrast of the document information obtained from the CCD 105 is confirmed (referenced) using the chart 301 shown in FIG. 5 while moving the imaging lens 106 back and forth on the plate 201 in the optical axis direction.

  As shown in FIG. 5, the contrast is confirmed at a plurality of image height positions (image reading positions), and the image is symmetrical about 50% or more of the maximum image height from the center in the main scanning direction around the optical axis and the optical axis. The contrast of document information at a high position is obtained and adjusted.

  By confirming the contrast at a plurality of image height positions including a position of 50% or more from the center of the optical axis, it is possible to perform focus adjustment at an average position with a good balance in the read image range. In this embodiment, the adjustment is performed based on the center of the optical axis and the image height position of 70%.

  Next, the procedure of this adjustment process will be described with reference to the flowchart of FIG.

  First, in the magnification measuring step in step S1, the magnification of the imaging lens is measured.

  Next, in the classification step of step S2, the imaging lenses are grouped based on the measurement result measured in step S1.

  That is, in the classification process of step S2, the number of imaging lenses is the same as the plurality of positions (2 or 4 positions) in the optical axis direction of the imaging lens set by the abutting means based on the magnification measurement result of step S1. Classify.

  In the temporary fixing step of step S3, an imaging lens is mounted on the plate to which the CCD is attached, and temporarily fixed.

  That is, in the temporary fixing step in step S3, the imaging lens is temporarily fixed to the plate on which the CCD is mounted so as to be movable in the optical axis direction.

  The steps up to step S3 are the preparation stage, and then the adjustment stage is entered.

  First, in the magnification measuring step in step S4, a plate on which an imaging lens whose group is known is mounted after being abutted either on the front or back from the imaging lens group to the carriage.

  That is, in the magnification measuring step in step S4, the plate on which the imaging lens and the CCD are mounted is projected on the carriage to one of a plurality of positions in the optical axis direction based on the measurement result of the magnification measurement of the imaging lens. The magnification of the imaging lens is adjusted by installing using the contact means.

  In the focus adjustment step of step S5, the temporarily fixed imaging lens is adjusted and attached while referring to the contrast while moving back and forth in the optical axis direction.

  That is, in the focus adjustment process in step S5, the focusing lens is adjusted by moving the imaging lens on the plate in the optical axis direction. Thereafter, the temporary fixing of the imaging lens is stopped and fixed on the plate.

  As described above, in this embodiment, by adjusting the magnification and focus of the imaging lens as described above, it is possible to make an adjustment for achieving both the magnification and the focus in a short time. Furthermore, the magnification and focus can be adjusted with high accuracy by mounting the imaging lens and the CCD on an integral plate.

  FIG. 7 is a perspective view of an essential part around the imaging lens and the CCD according to the second embodiment of the present invention. FIG. 8 is a perspective view of a main part of the plate on which the imaging lens and the CCD shown in FIG. 7 are attached. 7 and 8, the same elements as those shown in FIGS. 2 and 3 are denoted by the same reference numerals.

  The difference between the present embodiment and the first embodiment is that the long holes 402 of the plate 201 are formed at two locations in the optical axis direction. Other configurations and optical functions are the same as those in the first embodiment, and the same effects are obtained.

  That is, since the elongated holes 402 of the plate 201 are formed at two locations in the optical axis direction, the abutting portion is further increased, and in this case, adjustment in four stages is possible. As a result, as shown in FIG. 4B, the grouping is also divided into four ways of A, B, C, and D. For example, if the imaging lens 106 mounted on the plate 201 is the group A or B shown in FIG. 4B, the plate 201 is abutted against the rear side in the optical axis direction. In the case of C and D groups, the plate 201 is abutted against the front side in the optical axis direction.

  In the present embodiment, four-stage adjustment is possible as described above, and therefore, adjustment with higher accuracy than in the first embodiment described above can be performed.

  As described above, in this embodiment, the elongated holes 402 of the plate 201 are formed in two locations in the optical axis direction as described above, and the magnification and focus of the imaging lens are adjusted, so that both the magnification and the focus are achieved. Adjustment can be performed in a short time. Furthermore, the magnification and focus can be adjusted with high accuracy by mounting the imaging lens and the CCD on an integral plate.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  In each embodiment, the present invention is applied to an integrated (flatbed type) image reading apparatus. However, the present invention is not limited to this, and the present invention may be applied to an image reading apparatus having a 1: 2 scanning optical system. The present invention can be applied in the same manner as each embodiment.

Schematic diagram of essential parts of Embodiment 1 of the present invention 1 is a perspective view of a main part around an imaging lens and a CCD according to a first embodiment of the present invention. The perspective view of the principal part of the plate which the lens and CCD of Example 1 of this invention are attached. The figure which shows an example of lens group division of Example 1 of this invention The figure of the chart reading position of Example 1 of this invention Flowchart of Embodiment 1 of the present invention FIG. 6 is a perspective view of a main part around an imaging lens and a CCD according to a second embodiment of the present invention. The perspective view of the principal part of the plate which the lens and CCD of Example 2 of this invention are attached. Schematic diagram of main parts of a conventional image reading apparatus Flow chart of conventional adjustment method

Explanation of symbols

1 Image Reading Device 101 Document (Image)
102 Document base 103 Light source means 107 Integrated scanning optical system unit (carriage)
106 Imaging lens 105 Reading means (line sensor)
108 Driving Device 201 Plate 202, 402 Elongated Hole 203 Support Pin 301 Chart

Claims (5)

A light source means for illuminating the original; a plurality of mirrors for reflecting the light flux from the original illuminated by the light source means; an imaging lens for imaging the light flux reflected by the plurality of mirrors; and the imaging lens. An image reading device provided in an integrated scanning optical system unit with a photoelectric conversion element that receives the formed light and converts it into an electrical signal,
Movable means for allowing the imaging lens to move in the optical axis direction on a plate on which the photoelectric conversion element is mounted;
Abutting means for setting the plate on which the imaging lens and the photoelectric conversion element are placed at one of a plurality of positions in the optical axis direction on the integrated scanning optical system unit; An image reading apparatus. A light source means for illuminating the original; a plurality of mirrors for reflecting the light flux from the original illuminated by the light source means; an imaging lens for imaging the light flux reflected by the plurality of mirrors; and the imaging lens. A method of adjusting the magnification and focus of the imaging lens in an image reading apparatus provided with an integrated scanning optical system unit that receives a formed light and converts it into an electrical signal,
Based on the measurement result of the magnification measurement of the imaging lens at the one position among a plurality of positions in the optical axis direction on the integrated scanning optical system unit with the plate on which the imaging lens and the photoelectric conversion element are mounted. A magnification adjusting step for adjusting the magnification of the imaging lens by installing using the abutting means;
A focus adjustment step for adjusting the focus by moving the imaging lens on the plate in the optical axis direction after the magnification adjustment step;
A method for adjusting the magnification and focus of the imaging lens, comprising:   A classification step of classifying the imaging lens in advance into the same number as a plurality of positions in the optical axis direction of the imaging lens set by the abutting means based on the magnification measurement result; The method for adjusting the magnification and focus of the imaging lens according to claim 2.   4. The method for adjusting the magnification and focus of an imaging lens according to claim 2, wherein the focus adjustment step is performed with reference to a contrast of document information obtained from the photoelectric conversion element.   The focus adjustment step includes an image height position symmetrical to the optical axis at the maximum image height of 50% or more of the maximum image height on the optical axis of the imaging lens and in the main scanning direction from the original information obtained from the photoelectric conversion element 4. The method for adjusting the magnification and focus of an imaging lens according to claim 2, wherein the contrast is performed with reference to the contrast of the document information in step S2.

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