JPH09298639A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and highly accurately execute a focusing operation. SOLUTION: An original platen 22 is provided with original glass 26 for directly mounting a read original 24, a reference chart 28 for performing automatic focusing and a glass plate 31 to which a shading reference plate 30 for performing shading correction is mounted. For the reference chart 28, the three columns of patterns 34a-34c corresponding to various different optical magnifications are successively formed and a pattern 35 for position detection for detecting the position of the reference chart 28 is provided on the same line as the pattern 34a of a first column.

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 photoelectrically reading light containing image information carried on a read original.

[0002]

2. Description of the Related Art For example, a plane scanning type image reading apparatus normally provides an illuminating unit that moves in the sub-scanning direction while irradiating the reading document with illumination light in the main scanning direction, and image information carried on the reading document. An optical system that condenses the contained light as reflected light or transmitted light, and a reading unit that includes a solid-state image sensor such as a CCD that photoelectrically reads the condensed light containing image information.

By the way, when the reading operation by the image reading apparatus is continued, the temperature and humidity in the image reading apparatus fluctuate greatly. For this reason, the focus position of the condenser lens incorporated in the optical system is likely to change, and the reading accuracy is likely to deteriorate.

Therefore, conventionally, the work of reading the image of the read original document and adjusting the relative position between the optical system and the reading unit has been performed.

[0005]

However, in the above-mentioned prior art, since focusing is performed based on the image carried on the read document, after the image of the read document is searched,
This image must actually be scanned. As a result, it has been pointed out that the focusing work becomes considerably complicated and that an image suitable for the focusing work may not be selected, so that the focusing work cannot be performed with high accuracy.

The present invention solves this kind of problem, and an object of the present invention is to provide an image reading apparatus which can perform focusing work easily and with high accuracy.

[0007]

In order to solve the above-mentioned problems, the present invention is provided with a reference chart for autofocusing on an original placing table on which a read original is placed. Therefore, when the focus position of the optical system fluctuates due to changes in temperature and humidity inside the device, the autofocus is quickly and accurately performed using the reference chart.

Further, since the reference chart has a plurality of columns of patterns corresponding to various different optical magnifications, it is possible to efficiently deal with the change of the magnifications. Furthermore, by having the position detection pattern of the reference chart, it becomes possible to easily correct the position deviation of the reference chart itself due to mechanical error, change over time, or the like.

Further, the original glass on which the read original is directly placed and the glass plate on which the reference chart is mounted are mounted on the original mounting table while being integrally supported by the mounting member.
Therefore, one side of the original glass can be held by the glass plate on which the reference chart is mounted, and the attachment structure of the original glass and the glass plate can be effectively simplified.

[0010]

1 is a perspective view of an image reading device 10 according to an embodiment of the present invention, and FIG. 2 is a schematic perspective view of the inside of the image reading device 10 with a part thereof cut away. Three
FIG. 3 is an internal schematic configuration diagram of the image reading device 10.

The image reading apparatus 10 has a base portion 14 covered with a cover 12, and the base portion 14 has a first upper and lower portion.
The housing 16 and the second housing 18 are formed separately. A reference seat 20 that is a top plate is provided on the upper portion of the base portion 14.
Is provided, and the document table 22 is arranged on the reference seat 20 so as to be openable and closable.

A reflection type reading document 2 is placed on the document table 22.
4 (or a transmissive reading original 24a described later) is directly placed on the original glass 26, a reference chart 28 for performing autofocus, and a shading reference plate 30 which is a white plate for performing shading correction. The glass plates 31 mounted on the original mounting plate 22 are separately provided, and the original pressing plate 3 is mounted on the original mounting table 22.
2 is swingably arranged.

The reference chart 28 is composed of an exposed (black) sheet body mounted on the glass plate 31. As shown in FIGS. 1 and 4, in the reference chart 28, three rows of patterns 34a to 34c corresponding to various different optical magnifications are sequentially formed rearward in the sub-scanning direction (direction of arrow A), and Position detection patterns 35, 35 for detecting the position of the reference chart 28 are provided on the same line as the pattern 34a in the first column. Although not shown, the position detection pattern 35 has, for example, a plurality of doddle-shaped white portions.

Three rows of patterns 34a, 34b and 34
c corresponds to the sizes of A5, A3, and B3 (+ α), for example. As shown in FIG. 5, each pattern 34
a, 34b and 34c are five white slit portions 3 having a predetermined distance H and arranged at intervals of the distance H.
6a to 36e and one white slit portion 36f having a predetermined interval H, and the white slit portions 36a to 36e.
6e is provided at three locations, and the white slit portion 36f is provided at two locations. White slit portions 36a to 36
f has a constant length T, and each pattern 34a, 34b
And the interval H is set differently for each of 34c.

An opening 22a is formed in the original placing table 22, and an original glass 26 and a glass plate 31 are integrally attached to the opening 22a via a mounting member 38.

In order to obtain the light L containing the image information carried on the read original 24, the first original 16 is stored in the first original 2
And an illumination unit 40 that illuminates the illumination light La to
Moving mechanism 42 for moving 0 in the sub-scanning direction (direction of arrow A in FIGS. 2 and 3), and fixed-type optics for collecting light L containing the image information obtained through the illumination unit 40. A system 44 and a reading unit 46 that photoelectrically reads image information contained in the light L collected by the optical system 44 are provided.

The illumination section 40 comprises a light source unit 48 and a reflecting mirror unit 50. The light source unit 48 has a first bracket 52 provided on one end side (front surface side) of the base portion 14 in the lateral direction, and two halogen lamps 54a and 54b are provided on the first bracket 52. It is removably attached from the front side.

Reflector mirror blocks 56a and 56b for deflecting the respective light paths by 90 ° are arranged on the illumination light irradiation sides of the halogen lamps 54a and 54b. Quartz rods 58a and 58b extending in the scanning direction (arrow B direction) are provided. Below the quartz rods 58a and 58b, a reflecting mirror 60 for changing the optical path of the light L reflected by the read document 24 from the vertical direction to the horizontal direction is provided.

The reflecting mirror unit 50 has two reflecting mirrors 62a and 62b for changing the optical path of the light L reflected by the reflecting mirror 60 in the horizontal direction to guide it to the optical system 44. The reflecting mirrors 62a and 62b extend in the direction of arrow B and are attached to the second bracket 64.

The moving mechanism 42 includes a carrying motor 66, through which the light source unit 48 and the reflecting mirror unit 50 can read the original document 24 and the optical system 44.
It is supported by the pair of guide bars 72a and 72b and is sub-scanned and conveyed in the direction of arrow A without changing the optical path length between and (see FIG. 2).

As shown in FIG. 3, the optical system 44 includes a lens group 74 including a zoom lens, and an automatic zoom mechanism 76, an automatic iris mechanism 78, and an automatic focus mechanism 80 are provided on the optical path of the lens group 74. To be
The autofocus mechanism 80 is configured to perform autofocus by displacing the reading unit 46 with respect to the lens group 74. N in front of the lens group 74
The D filter 82 is swingably provided so as to be arranged on the optical path of the lens group 74 and outside the optical path.

The reading section 46 is arranged on the optical path of the light L and is fixed to the optical system 44 integrally with three color separation prisms 116a to 116c, and the color separation prism 116a.
~ 116c to read image information contained in each color of light photoelectrically, the color separation prism 116a ~
It has a plurality of CCDs (solid-state image pickup devices) 118a to 118c integrally fixed to 116c. The color separation prisms 116 a to 116 c receive the light L reflected from the read document 24.
Is separated into three primary colors of R, G and B, and each CCD 118a-1
Leads to 18c.

As shown in FIG. 2, the first accommodating portion 16 includes
The cooling mechanism 140 is disposed on the front surface side of the base portion 14. The cooling mechanism 140 is rotated via the motors 144 and 146, and is long in the arrow A direction.
8, 150.

As shown in FIGS. 2 and 3, the second accommodating portion 18 is provided with a power source 160 and a control portion 162. The control unit 162 includes a lighting unit 40, a moving mechanism 42,
Various substrates 164a to 164n for driving and controlling the optical system 44 and the reading unit 46 are provided. For example, the CCDs 118 a to 118 c forming the reading unit 46 are connected to the drive board 164 b via the flexible cable 166.

A transmissive illumination unit 170 for reading the transmissive read original 24a can be attached to the image reading apparatus 10. As shown in FIGS. 1, 6 and 7.
The transillumination unit 170 includes a main body unit 172 directly arranged on the document placing table 22 from which the document pressing plate 32 is removed.

The main body 172 is formed to be long in the sub-scanning direction (direction of arrow A), and a conveying motor 174 is attached to one inner end thereof. A drive pulley 178 is rotatably mounted on a drive shaft 176 extending upward from the transport motor 174. The drive belt 178 and a driven pulley 180 disposed at the other inner end of the main body 172 are attached to the transport belt 182.
Is installed.

The conveyor belt 182 has a movable casing 1
84 is fixed. The moving casing 184 is configured to be long in the main scanning direction (direction of arrow B), has a plurality of rollers 186 that roll on the document table 22, and has a halogen light source as a light source on one end side thereof. The lamp 188 is mounted. On the illumination light irradiation side of the halogen lamp 188, a reflector block 19 for deflecting the optical path by 90 ° is provided.
0 is arranged, and a quartz rod 192 extending in the main scanning direction is provided on the illumination light lead-out side of the reflecting mirror block 190. A cooling fan 194 for cooling the halogen lamp 188 is arranged in the moving casing 184 (see FIG. 6).

A document pressing plate 196 is used to bring the read document 24a into close contact with the document table 22. The document holding plate 196 is made of a white plate and is also used for shading correction. As shown in FIGS. 1 and 6, a stepped opening 198 for a handle is formed at one end of the document pressing plate 196, and the image reading device 1 is also provided.
A locking portion 200 for supporting the document pressing plate 196 through the stepped opening 198 is provided on the side of 0.

The operation of the image reading apparatus 10 thus constructed will be described below.

When the image information carried on the reflection type reading original 24 is read, first, the original holding plate 32 is opened and read on the original glass 26 constituting the original placing table 22. The document 24 is placed directly with the reading surface facing down. Further, by closing the document pressing plate 32, the read document 24 is placed in close contact with the document glass 26.

Next, the halogen lamps 54a and 54b in the light source unit 48 constituting the illumination section 40 are energized and the moving mechanism 42 is driven. The illumination light La emitted from the halogen lamps 54a and 54b is deflected by 90 ° by the reflecting mirror blocks 56a and 56b and guided to the quartz rods 58a and 58b.
The reading surface of the read document 24 is irradiated from 8b through the document glass 26. The light L reflected by the read original 24 passes through the original glass 26 and reaches the reflecting mirror 60. After the optical path is changed from the vertical direction to the horizontal direction by the reflecting mirror 60, the reflecting mirror in the reflecting mirror unit 50. It is reflected by 62a and 62b and guided to the optical system 44.

The light L guided to the optical system 44 is condensed by a lens group 74 including a zoom lens, and then separated into three primary colors of R, G and B by color separation prisms 116a to 116c, respectively CCD 118a to. Irradiation is performed on the light receiving surface of 118c. The image information projected onto the light-receiving surfaces of the CCDs 118a to 118c is converted into an electric signal and then transmitted through the flexible cable 166 to the substrate 164b.
Sent to

On the other hand, when the conveying motor 66 constituting the moving mechanism 42 is driven, the light source unit 48 and the reflecting mirror unit 50 do not change the optical path length between the read original 24 and the optical system 44, and That is, the reflecting mirror unit 50 is sub-scanned and conveyed in the direction of arrow A at a movement distance that is half that of the light source unit 48.

By the above operation, the light source unit 48 and the reflecting mirror unit 50 are moved from the position indicated by the solid line to the position indicated by the alternate long and two short dashes line in FIG. 3, and all the image information carried on the read document 24 is read. Become.

By the way, as described above, when the operation of reading the image information carried on the read document 24 is continued, a temperature change and a humidity change occur inside the image reading apparatus 10,
The focus position of the optical system 44 easily changes.

Therefore, in the present embodiment, the reference chart 2
By using 8, autofocus is performed quickly and with high accuracy. That is, after the illumination section 40 is arranged at a position corresponding to the reference chart 28 under the action of the moving mechanism 42, the halogen lamp 54 that constitutes the light source unit 48.
a and 54b are driven. Therefore, the halogen lamp 5
The reference chart 28 is irradiated with the illumination light La from the reference numerals 4a and 54b through the quartz rods 58a and 58b and the glass plate 31, and the light L reflected by the reference chart 28 is guided from the optical system 44 to the reading unit 46. CCD 118a-1
Imaged at 18c.

Next, the autofocus mechanism 80 is driven and the reading section 46 moves with respect to the lens group 74, so that the reading section 46 is located at the focal position of the lens group 74.
The light receiving surfaces of the CCDs 118a to 118c are arranged.

As described above, in the present embodiment, the reference chart 28 is disposed in the vicinity of the original glass 26, and the lens group 74 and the CCDs 118a.about. Are used by using the reference chart 28.
Autofocusing with 118c is performed. Therefore, when the focus position of the optical system 44 changes due to changes in the temperature and humidity inside the image reading apparatus 10, there is no need to actually search for the image of the read document 24 as in the conventional case, and autofocus is quick and high. The effect of being carried out with precision is obtained.

Further, the reference chart 28 has a plurality of rows of patterns 34a to 34c corresponding to various different optical magnifications.
Is provided. Therefore, even when the magnification is changed over the size of A5 to B3 (+ α), the pattern 34
Only by selectively using a to 34c, it is possible to cope efficiently.

Further, the reference chart 28 is provided with a pattern 35 for detecting the position of the reference chart 28. As a result, when the reference chart 28 itself is displaced due to a mechanical error, a change with time, or the like, the pattern 35 is detected, so that the patterns 35 are used as reference positions to easily and easily form the patterns 34a to 34c. It is possible to reliably position. Moreover, since the pattern 35 is provided on the same line as the pattern 34a in the first column, the width dimension of the reference chart 28 can be effectively shortened.

Furthermore, the glass plate 31 on which the reference chart 28 is mounted and the document glass 26 are mounted on the document mounting table 22 while being integrally supported by the mounting member 38. Therefore, there is an advantage that one side of the original glass 26 can be directly held by the glass plate 31, and the attachment structure of the original glass 26 and the glass plate 31 can be effectively simplified.

By the way, in the image reading apparatus 10 according to the present embodiment, it is possible to read the image information carried on the transmissive read original 24a in addition to the reflective read original 24.

That is, in FIG. 1, the document holding plate 32
After the document is removed from the document placing table 22, the transillumination unit 17
0 is placed on the original placing table 22. After the read original 24a is placed on the original glass 26 of the original placing table 22, the original 24a is brought into close contact with the original glass 26 by the original pressing plate 196 (FIGS. 6 and 7).
reference).

Then, the halogen lamp 188 is energized so that the illumination light La is emitted from the reflecting mirror block 190 to the quartz rod 1.
The reading light 24a is guided to the reading light source 92 and is irradiated with the illumination light La through the quartz rod 192 to the read document 24a on the document placing table 22. At that time, the transportation motor 174 is drive-controlled in synchronization with the transportation motor 66 that constitutes the moving mechanism 42. For this reason, the moving casing 184 is mounted via the transport belt 182 stretched between the drive pulley 178 fixed to the drive shaft 176 of the transport motor 174 and the driven pulley 180.
Is conveyed in the direction of arrow A, and the first bracket 52 is conveyed integrally with the moving casing 184 in the direction of arrow A (see FIG. 7).

Therefore, the illumination light La emitted from the quartz rod 192 is emitted from the original holding plate 196 and the read original 24a.
Is guided to the reflecting mirror 60 in the first bracket 52, and is further guided from the reflecting mirror 60 to the optical system 44 via the reflecting mirrors 62a and 62b in the reflecting mirror unit 50.
As a result, when the moving casing 184 is conveyed in the direction of arrow A and is moved from the position indicated by the solid line to the position indicated by the alternate long and two short dashes line in FIG. 7, all the image information carried on the read document 24a can be read. become.

In this case, the reference chart 28 can be used for autofocusing the transmissive read original 24a. That is, like the reflective read original 24, the illumination unit 40 is driven to drive the halogen lamps 54 a, 5 a.
4b illuminates the reference chart 28 with the illumination light La, and the light L obtained from the reference chart 28 is applied to each CCD 118.
a to 118c. Then, under the driving action of the autofocus mechanism 80, autofocus corresponding to the transmissive read original 24a is performed.

As a result, the reflective read original 24 and the transmissive read original 24a can be efficiently dealt with by the single reference chart 28, and the structure can be simplified and the cost can be easily reduced. The effect is obtained.

[0048]

As described above, in the image reading apparatus according to the present invention, since the reference chart for performing the autofocus is provided on the document table on which the read document is placed, the temperature and humidity inside the apparatus can be controlled. When the focal position of the optical system fluctuates due to the change, the autofocus is performed quickly and highly accurately by using the reference chart.

[Brief description of drawings]

FIG. 1 is a perspective view of an image reading apparatus according to the present invention.

FIG. 2 is a schematic perspective view of the inside of the image reading device with a part thereof cut away.

FIG. 3 is a schematic configuration diagram of the inside of the image reading apparatus.

FIG. 4 is a perspective explanatory view of a reference chart constituting the image reading apparatus.

FIG. 5 is a partially enlarged explanatory view of the reference chart.

FIG. 6 is a cross-sectional plan view of a transillumination unit that constitutes the image reading apparatus.

FIG. 7 is a diagram illustrating a reading operation of a transmissive read original by the transillumination unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Image reading device 14 ... Base part 16, 18 ... Accommodating part 22 ... Original placing table 24, 24a ... Read original 26 ... Original glass 28 ... Reference chart 31 ... Glass plates 34a-34c, 35 ... Pattern 36a-36f ... White slit section 38 ... Mounting member 40 ... Illumination section 44 ... Optical system 46 ... Reading section 48 ... Light source unit 50 ... Reflector unit

Claims (4)

[Claims] 1. A document placing table for placing a read document, an illuminating unit for irradiating the read document with illumination light to obtain light including image information carried on the read document, and the illuminating unit. An optical system for condensing the light containing the image information obtained via the optical system; and a reading unit for photoelectrically reading the image information contained in the light condensed by the optical system. Is an image reading apparatus characterized in that a reference chart for autofocus is provided. 2. The image reading apparatus according to claim 1, wherein the reference chart has a plurality of rows of patterns corresponding to various different optical magnifications. 3. The image reading apparatus according to claim 1, wherein the reference chart has a position detection pattern for detecting the position of the reference chart. 4. The image reading apparatus according to claim 1, wherein the original placing table has an original glass on which the read original is directly placed, a glass plate on which the reference chart is mounted, the original glass and the glass. An image reading apparatus, comprising: an attachment member that integrally supports a plate and is attached to the document placing table.