JP2556574Y2 - Image reading device - Google Patents

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, and more particularly, to an image reading apparatus having a scanning optical system in which a light source and a reflecting mirror move, the direction of incidence on a document, and the optical axis of the reading optical system. The present invention relates to an image reading apparatus capable of achieving an improvement in reproduction image quality by blocking illumination light having an angle of less than a predetermined angle.

[0002]

2. Description of the Related Art Various types of image reading apparatuses for irradiating a document placed on a document table with illumination light and introducing reflected light from the document into a reading optical system to obtain a reproduced image of the document have been put to practical use. ing. Among such image reading apparatuses, there is known a light source moving type image reading apparatus that scans a document by moving a light source unit including a light source and a reflecting mirror. In this type of image reading apparatus, a movable light source unit condenses illumination light of the light source with a concave mirror and irradiates the original in a belt shape.

By the way, generally, fine irregularities exist on the surface of a document sheet carrying image information. Therefore, when the illumination light is reflected on the surface of the original, the reflected light incorporates information on the unevenness on the paper surface in addition to the image information carried on the original, and the reproduced image has the shading based on the unevenness on the paper surface. May appear. Although such a phenomenon varies depending on the paper quality of the paper used for the original, it is confirmed that the phenomenon is particularly remarkable when a silk type of color paper is used for the original. That is, conventionally, there has been a problem that the sharpness of a reproduced image is deteriorated due to unevenness of the surface of a sheet.

For this reason, the present applicant has disclosed in Japanese Patent Laid-Open No.
No. 936, a light source for converging illumination light emitted from a light source by a concave mirror and using a light source moving type scanning optical system having a light source unit for illuminating a document in a band shape is used for condensing illumination light. A combination of one or more elliptical mirrors and a plane mirror is used as the reflecting mirror, and the direction of incidence of the illumination light reflected by the ellipsoidal mirror and the plane mirror is set to the reading optical axis of the illumination light reflected on the original. An image reading device in which the angle is set to 35 ° or more has been proposed.

[0005]

[Problems to be Solved by the Invention]
The image reading device proposed in Japanese Patent No. 111936 is capable of avoiding the influence of the surface irregularities on the original paper surface on the reproduced image and clearly reproducing only the image information on the original document. Since one or more surface mirrors are used, there is a problem that the image reading apparatus becomes expensive.

On the other hand, a so-called aperture type fluorescent tube has been used as a light source of an image reading apparatus to which such a light source moving type scanning optical system is applied. This aperture type fluorescent tube is provided with a reflective coating inside the fluorescent tube except for the slit, and emits band-like illumination light (slit light) from the slit, and emits directional slit light. Can be. However, even if the angle between the incident direction of the slit light of the fluorescent tube and the reading optical axis for the reflected light from the document is regulated to, for example, 35 ° or more, the reproduced image of the document caused by the irregularities on the surface of the document is not affected. There is a problem that deterioration of definition cannot be prevented.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. A light-shielding plate is provided in the middle of the optical path from a rod-like light source that emits band-like illumination light (slit light) to a document. By blocking the illumination light whose incident angle is less than the predetermined angle, it is possible to eliminate the effect of the surface irregularities on the original paper surface on the reproduced image and to reproduce only the image information on the original clearly. It is an object of the present invention to provide an image reading apparatus.

[0008]

Means for Solving the Problems In order to solve the above problems, the present inventor has conducted intensive studies on an image reading apparatus using an aperture type fluorescent tube for emitting a band-like illumination light as a light source. The scattered light of the emitted slit light (band-like illumination light) is applied to the original, the light carrying the information of the unevenness of the original is reflected by the original, enters the reflected light carrying the original image, and the image quality of the reproduced image is obtained. The present inventors have found that the present invention deteriorates, and have led to the present invention.

That is, the present invention is applied to a printing plate making apparatus.
An image reading apparatus that irradiates a document with a band-shaped illumination light emitted from a rod-shaped light source that moves at a predetermined speed in one direction, and reads image information carried on the document from light reflected by the document, disposed a shielding plate for regulating the optical path of the illumination light on the way from the light source of the optical path leading to the document, the illumination direction of incidence angle is less than 35 degrees with the reading light axis of the reflected light from the original shields the light, caused the unevenness of the document
Accordingly, it is an object of the present invention to provide an image reading apparatus characterized in that the deterioration of the sharpness of a reproduced image caused by the image reading is prevented .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings. FIG.
1 is a schematic sectional view of an embodiment of the image reading apparatus of the present invention.

An image reading apparatus 10 schematically shown in FIG.
A document placement unit 12 on which the document 11 is placed with the document surface facing down; a light source unit 13; a mirror unit 14 for changing an optical path L of reflected light carrying a document image from the document 11; Imaging lens 15 for imaging the reflected light
And a reading unit 16 arranged at an image forming position of the reflected light and receiving the reflected light and reading the image information photoelectrically.

The original placing section 12 includes a platen glass 17 made of a transparent glass plate and a platen glass 17.
A document pressing plate 18 for pressing the document 11 placed thereon to prevent the document from being displaced.

Below the platen glass 17, a light source moving type scanning optical system comprising a light source unit 13 and a mirror unit 14 is provided. In this scanning optical system, the light source unit 13 moves in a sub-scanning direction indicated by an arrow A in the drawing at a predetermined speed (v) under the driving action of a driving mechanism (not shown), and the mirror unit 14
Move in the same direction at a speed (1 / 2.v) that is half the moving speed.

The light source unit 13 is, as shown in FIG.
A fluorescent tube, which is a rod-shaped light source that emits a band-shaped illumination light (slit light) in one direction, a so-called aperture-type fluorescent tube 19
a, 19b and originals 11 from the fluorescent tubes 19a, 19b.
Are arranged in the optical path of the illumination lights 20a and 20b so as to be incident at an incident angle of about 35 degrees or more, and shield the illumination lights having angles .theta.1 and .theta.2 with the reading optical axis 22 of less than 35 degrees. And a first mirror 23 that reflects the reflected light 90 by 90 degrees along the optical axis 22 read from the document 11. Here, the aperture type fluorescent tubes 19a and 19b are fluorescent tubes that irradiate illumination light in one direction from a band-shaped window (slit) 24 as shown in FIG.

The light-shielding plates 21a and 21b have an L-shaped cross section, and upper ends 25a and 25b have fluorescent tubes 19a and 19b, respectively.
b, the illumination light emitted from the band-shaped window is restricted to θ1, θ
2 is configured such that illumination light of less than 35 degrees does not enter the document surface. For example, as shown in FIG.
The upper ends 25a and 25b are configured to be located below a straight line 26a or 26b connecting the windows of the fluorescent tubes 19a and 19b and the document surface. Lower side 27 of light-shielding plates 21a and 21b
The slits a and 27b regulate the length and width of the belt-like reflected light L carrying the document image, which is reflected by the document 11, and regulate the passage of unnecessary light and the like. A lamp house 29 that covers the fluorescent tubes 19a and 19b is provided outside the fluorescent tubes 19a and 19b.
There is a slit 30 for passing the slit-like reflected light L reflected by the light 1 and passing through the slit 28 as slit light having a predetermined slit width and length immediately below.

Next, the light reflected along the reading optical axis 22 is
The reflected light L reflected by the first mirror for deflecting the optical path L of the reflected light carrying the document image is introduced into the mirror unit 14. The mirror unit 14 has a first
A second mirror 31 and a third mirror 32 for deflecting the optical path of the reflected light from the mirror 23 at every 90 degrees are provided. The reflected light L reflected by the third mirror 32 passes through the imaging lens 15 fixed at a predetermined position and enters the reading unit 16. The reading unit 16 is disposed at an image forming position of the reflected light L by the image forming lens 15, and photoelectrically converts a document image of one line of the document irradiated by the predetermined band-shaped illumination light into one block to perform analog electric signal as image density data. And an image processing device 34 for processing and storing data photoelectrically read by the CCD 33
And The CCD 33 is a licensor that photoelectrically converts a document image for one line of main scanning and outputs it as an analog image data signal for one line of main scanning. The CCD 33 is not limited to this, and various licensors can be used.

The image processing device 34 generates a main scanning clock which determines the timing of reading one line of image data from the CCD 33, and converts an analog image data signal read from the CCD 33 based on the main scanning clock. After analog correction such as gain correction, A is converted to an image data signal as a digital signal.
A / D converter, a memory for storing the digital image data, and an image processing section for performing image processing on the image data signal and finally outputting it as an image signal for recording, for example, a halftone image signal to an image recording device (not shown) Consists of Here, the image processing unit is a processing circuit that performs various processes described below necessary for generating a halftone image signal, a CPU that performs calculations and determinations of various image data signals, and stores various data including image data. And a memory such as a RAM or a ROM.

In the reading of image information by the image reading apparatus according to the present invention, first, as shown in FIG. 1, an original 11 is placed on a platen glass 17 in an original placing section 12, and this is placed on an original pressing plate. Press 18 to fix it so that it does not shift.

Next, in the figure, the light source unit 13 is moved at a predetermined speed (v) in the sub-scanning direction indicated by an arrow A under the driving action of a driving mechanism (not shown), and the mirror unit 14 is moved at the moving speed of the light source unit 13. Half the speed (1 /
It is moved in the same direction in 2 · v). Here, in the light source unit 13, aperture type fluorescent lamps 19a and 19b are provided.
Is incident on the document 11 at an angle of 35 degrees or more with respect to the reading optical axis 22. At this time, the light-shielding plates 21a and 21b cause the fluorescent tubes 19a and 19b, respectively.
b, illumination light 20a, 20b emitted toward the original
To block the illumination light having an incident angle θ1 or θ2 of less than 35 degrees, the illumination light of less than 35 degrees is incident on the original surface, and the illumination light provides information on the irregularities on the original surface. Without being captured, the image reproduced by the image recording apparatus based on the image density data read by the reading unit 16 does not appear on the image due to the unevenness on the paper surface, and the deterioration of the sharpness of the reproduced image is prevented. You.

The image information carried on the original 11 is reflected on the surface of the original 11 by the first mirror 2 as reflected light.
3, the optical path is changed by the second mirror 31 and the third mirror 32, and the CCD 3 of the reading unit 16 is changed by the imaging lens 15.
An image is formed on the image 3, photoelectrically converted by the CCD 33, and stored in the image processing device 34.

The image reading apparatus 10 of the present invention is basically configured as described above, and can be applied as an image reading apparatus of the printing plate making apparatus 40 shown in FIG. Since the image reading apparatus 10 is the same as the image reading apparatus 10 shown in FIGS. 1 and 2, the same components are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 1, the printing and plate making apparatus 40 comprises an image reading apparatus 10, an image processing apparatus 34, and an image recording apparatus 41.
And a photosensitive material processing device 43. The printing plate making apparatus 40 scans an image of the original 11, for example, a continuous tone image by the image reading apparatus 10 in the sub-scanning direction indicated by the arrow A in FIG. (In the direction perpendicular to the direction) The photoelectric signal is read photoelectrically for each line, and is converted into a halftone image signal binarized by the image processing device 34. The image signal is then transferred onto the photosensitive material F by the image exposure device 42 of the image recording device 41. Exposure is recorded as a halftone image, and the photosensitive material processing unit 43 reproduces the image by performing processing such as development, bleaching, fixing, and washing with water and drying.

As shown in FIG. 4, the image exposure device 42
The image processing device 3 is read by the image reading device 10 and
A recording light source 4 for emitting a recording beam modulated in accordance with the halftone image signal processed, generated and transmitted
4, a resonant scanner 45 for deflecting the recording beam in a one-dimensional direction (main scanning direction), an fθ lens 46 for adjusting the focus of the deflected scanning beam on the photosensitive material F, and a magazine 47 disposed above. An exposure drum 48 for conveying (sub-scanning direction) the specified photosensitive material F at an exposure position, nip rollers 49 and 50 for pressing and transporting the photosensitive material F to the exposure drum 48, and It has a cutter 51 for cutting to a predetermined length, and a photosensitive material transporting or recording motor 52 for driving the exposure drum 48. Further, a synchronization signal detector for controlling exposure may be provided.

The recording beam emitted from the recording light source 44 modulated according to the halftone image signal R is deflected in a one-dimensional direction by a resonant scanner 45, passes through an fθ lens 46, and is extracted from a magazine 47. Exposure drum 4
The photosensitive material F conveyed in the sub-scanning direction by the nip rollers 49 and 50 is exposed, and a halftone dot image is recorded two-dimensionally.
Simultaneously, a synchronizing signal is generated from a synchronizing signal detector (not shown), and the exposure is controlled by the recording beam, whereby accurate and favorable exposure can be performed.

After the exposure is completed, the exposed photosensitive material F cut
Is sent to the photosensitive material processing device 43. The photosensitive material processing device 43 has a developing tank 53, a bleach-fixing tank 54, a washing tank 55, and a drying unit 56, and these wet processing tanks 53 and 5 are provided.
In steps 4 and 55, the exposed photosensitive material F is subjected to wet processing such as development, fixing, bleaching, and washing with water, and then dried in a drying unit 56, and is discharged to a takeout tray 57 as a plate-making film. The reproduced image on the plate making film discharged to the take-out tray 57 is a clear image without image quality deterioration due to unevenness of the document 11.

The image reading apparatus of the present invention performs reading by the CCD as described above, and is for digital exposure after reading. However, the present invention is not limited to this. As shown, an image reading apparatus of an image forming apparatus that performs analog exposure may be used. The image forming apparatus 60 shown in FIG. 5 is exactly the same except for the reading unit 16 of the image reading apparatus 10 shown in FIG. 1, and therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

The image forming apparatus 60 shown in FIG. 5 includes an original placing section 12, a light source unit 13, and a mirror unit 14.
, An image reading device 61 and an image exposing device 62 each including an image forming lens 15, and irradiates the original 11 with illumination light emitted from the light sources 19a and 19b.
The reflected light L reflected by the light is imaged directly on the photosensitive material F by the imaging lens 15, and the reflected light L
Is to directly expose a document image on a photosensitive material as a latent image or a visible image.

The image exposure device 62 includes a light-shielding plate 64 having a slit 63 defined therein, guide members 65 and 66 provided in parallel with a predetermined space therebetween, and the guide members 65 and 66.
And a pair of conveying rollers 67a, 67b and 68a, 68b for conveying the photosensitive material.

In the image forming apparatus 60, the image information carried on the original 11 is reflected by the first mirror 23, the second mirror 31, and the third mirror 32 as reflected light on the surface of the original 11, and the light path L is changed. The image is formed on the photosensitive material F in the image exposure device 62 by the image lens 15. Photosensitive material F
Are transport rollers 67a, 67b and 68 which rotate in the direction of the arrow at the same time as the start of scanning by the light source unit 13.
The image data is sent in the direction of arrow B by a and 68b, and the read image information is recorded.

In the embodiments shown in FIGS. 1 to 5 described above, a pair of fluorescent tubes for irradiating the original with illumination light in the light source unit are arranged symmetrically with respect to the reading optical axis. The present invention is not limited to this mode, and it is needless to say that the present invention can be applied to a case where only one fluorescent tube is arranged. The light source used in the present invention is not limited to the above-described aperture type fluorescent tube, and may be any light source that can emit directional band-shaped illumination light such as slit light.

Further, the light shielding plate is not limited to those shown in FIGS.
What is necessary is just to be able to block the illumination light of less than degree.

[0032]

According to the image reading apparatus of the present invention, a light-shielding plate is provided in the middle of the optical path from the rod-like light source that emits the band-like illumination light to the original, and the incident angle is smaller than a predetermined angle. By blocking the light, it is possible to eliminate the influence of the unevenness on the surface of the document on the reproduced image and to reproduce only the image information on the document clearly.

[Brief description of the drawings]

FIG. 1 is a schematic sectional configuration diagram of an embodiment of an image reading apparatus according to the present invention.

FIG. 2 is an explanatory sectional view of a main part of the image reading apparatus shown in FIG.

FIG. 3 is a schematic perspective view of an aperture type fluorescent tube used in the image reading apparatus shown in FIG.

FIG. 4 is a schematic cross-sectional configuration diagram of an embodiment of a printing plate making apparatus to which the image reading apparatus shown in FIG. 1 is applied.

FIG. 5 is a schematic sectional configuration diagram of another embodiment of the image reading apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Image reading apparatus 11 Document 12 Document placement part 13 Light source unit 14 Mirror unit 15 Imaging lens 16 Reading part 17 Platen glass 18 Document pressing plates 19a, 19
b Fluorescent tube 20a, 20b Illumination light 21a, 21
b Shielding plate 22 Reading optical axis 23 First mirror 24 Belt-shaped window (slit) 25a, 25
b Upper end 26a, 26b Straight line 27a, 27
b Underline 28, 30 Slit 29 Lamp house 31 Second mirror 32 Third mirror 40 Printing and plate making device 41 Image recording device 42 Image exposing device 43 Photosensitive material processing device 60 Image forming device 61 Image reading device 62 Image exposing device

Claims (2)

(57) [Scope of request for utility model registration] 1. An original which is used in a printing plate making apparatus and irradiates a document with a band-like illumination light emitted from a rod-like light source which moves in one direction at a predetermined speed, and an image carried on the document from light reflected by the document. an image reading apparatus for reading information, arranged a light shielding plate for regulating the optical path of the illumination light on the way from the light source of the optical path leading to the document, formed by the reading light axis of the reflected light from the original The illumination light in the incident direction having an angle of less than 35 degrees is shielded, and the reproduced image due to the unevenness of the original is sharpened.
An image reading apparatus characterized in that brightness deterioration is prevented . 2. The image reading apparatus according to claim 1, wherein said light source is an aperture type fluorescent tube.