JP2783482B2 - 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 a flat-scanning type image reading apparatus which illuminates a transmission type or reflection type original with illumination light from a Koehler illumination optical system unit and reads out obtained image light by a line sensor.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus that photoelectrically reads image information recorded on a document such as a film, subjects the image information to desired image processing, and creates a film original for printing and plate making has been widely used. Have been.

An image reading optical system in such an image reading apparatus, for example, focuses illumination light emitted from an illumination light source as light linearized by a slit member or the like.
The light is irradiated on the read original, and then the light transmitted through the read original is condensed through a condenser lens and read by a line sensor. In this case, in order to guide the light to the light receiving surface (usually 7 to 10 μm in width) of the very narrow line sensor while avoiding the flare, it is necessary to linearize the light illuminating the read original with a slit member or the like.

[0004] By the way, in such a configuration, the linearized light may not be accurately guided to the line sensor. In particular, line sensors, condenser lenses,
This is likely to occur when a transparent original or the like is moved in the optical axis direction to change the optical magnification of an image. This is because, for example, when the condenser lens is moved in the optical axis direction, an inevitable minute displacement of the condenser lens occurs. If the condensing lens is displaced, the line sensor cannot accurately read the image information because the linear light band obtained from the read document does not exactly match the light receiving surface of the line sensor. As a result, the image may deteriorate or only part of the image information may be obtained.

In order to match the line connecting the maximum light quantity position of the linearized illumination light and the position of the line sensor, the present applicant has controlled the slit position adjusting mechanism and the slit position adjusting mechanism. A slit positioning device provided with means has been proposed (see Japanese Utility Model Laid-Open No. 2-137163 and Japanese Patent Laid-Open No. 2-280455).

[0006]

SUMMARY OF THE INVENTION The present invention has been made in connection with the above-mentioned proposal, and is an illumination optical system having no illumination unevenness, such as a Koehler, as means for linearizing light emitted from a light source. An illumination optical system is adopted, and a field stop which is disposed in the Koehler illumination optical system and forms an image of a linearized illumination light source on a read original is changed by a magnification conversion operation by a magnification conversion mechanism of the image reading apparatus. An image reading apparatus capable of easily matching the maximum light amount position of linearized illumination light corresponding to the light receiving surface of a line sensor for reading image light by adjusting by displacing and adjusting the image reading apparatus. The purpose is to do.

Further, the present invention provides a magnification of an image reading apparatus by defining a slit having a variable width, length or the like in a field stop, or defining a plurality of slits having different widths or lengths. It is an object of the present invention to provide an image reading device capable of setting an illumination width according to an optical magnification by a conversion mechanism.

[0008]

In order to achieve the above object, the present invention has an optical magnification conversion mechanism, and reads transmitted light or reflected light from a read original by a line sensor to obtain image information. In the image reading apparatus, an illumination light source, a first condenser lens for condensing illumination light from the illumination light source, and a second condenser lens for guiding illumination light from the first condenser lens to a read original An illumination optical system including a field stop provided between the first condenser lens and the second condenser lens to form a linear image of an illumination light source on the read original A position adjusting mechanism for adjusting the position of the line sensor by displacing the field stop in a direction orthogonal to a line direction of the image of the linearized light source for illumination. .

The field stop has a slit whose width and / or length is variable.

Further, the field stop has a plurality of slits having different widths and / or lengths.

Still further, the illumination optical system is a Koehler illumination optical system.

[0012]

In the above-described image reading apparatus according to the present invention, for example, when the optical magnification is changed by the optical magnification conversion mechanism, the image of the illumination light source whose entire field stop is linearized through the position adjustment mechanism. By displacing in the direction orthogonal to the line direction, the position of the line sensor is adjusted.
Further, the width of the slit defined in the field stop and / or
Alternatively, by adjusting the length or selecting from a plurality of slits having different widths and / or lengths, an appropriate illumination width according to the optical magnification is obtained. Further, by adopting a Koehler illumination optical system as the illumination optical system, an image of a linear illumination light source is formed without illumination unevenness.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of an image reading apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

1 and 2, a Koehler illumination optical system unit (hereinafter, simply referred to as an illumination optical system) 12 and a illumination optical system 1 constituting a reading section 10 of an image reading apparatus.
The second position adjustment mechanism 14 is disposed on a base plate 18 via a substrate 16. The four corners of the base plate 18 are respectively provided with adjusting screws 2 on a horizontal surface plate 20 fixed to the main body of the image reading apparatus.
It is fixed via 2a, 22b. Positioning pins 23a and 23b for attaching the base plate 18 to the horizontal surface plate 20 are provided at substantially the center of both ends of the base plate 18. A substrate 16 is disposed on a plane of the base plate 18, and the substrate 16 is provided with a pin member 17 provided at one end side as a fulcrum and engaged with elongated holes 19a and 19b defined at the other end side. , 21b so as to be swingable in the direction of arrow A or B. The illumination optical system 12 is disposed in a casing 24 erected on the substrate 16. A base 26 is connected to a lower portion of the casing 24, and both ends of the base 26 are formed with long holes 30 that engage with screw members 28. It is formed so as to be displaceable in the C direction. Side plates 32 are provided on both sides of the base plate 18 and the substrate 16, respectively.
a, 32b and 34a, 34b are provided. As will be described later, adjustment screws 36a and 36b having substantially the same configuration as the adjustment screws 22a and 22b are provided on the side wall portion 34b arranged adjacent to the position adjustment mechanism 14. On the other hand, the side wall portion 34a juxtaposed close to the illumination optical system 12 is also provided with three adjusting screws 38a to 38c having substantially the same configuration as the adjusting screws 22a and 22b.

The Koehler illumination optical system unit 12 includes a light source 40 at the upper end of the casing 24 and a pair of cylindrical lenses 42a and 42 disposed below the light source 40.
b, a field stop 44 disposed below the cylindrical lenses 42a and 42b, a filter 46 and a brightness stop 48 disposed below the field stop 44, and a light source disposed below the brightness stop 48. And a pair of cylindrical lenses 50a and 50b provided. An opening 52 for allowing light to pass therethrough is defined in the substrate 16 and the base plate 18 on which the illumination optical system 12 is erected, and a vertically lower portion of the opening 52 is made of nanglare glass. A read original 58 sandwiched between the cover glass 54 and the support glass 56 is arranged, and has a condensing lens 60 for condensing light transmitted through the read original 58, and a light receiving surface for receiving the transmitted light, A line sensor (for example, a CCD) 62 for converting the received light into an electric signal is provided. The field stop 44 has one end connected to a driving plate, which will be described later, and has a plurality of slits 64a and 64b having different slit widths and lengths according to the image magnification, as shown in FIG. In this embodiment, two types of slits 64a having different widths and lengths,
Although the description is made using 64b, it goes without saying that a plurality of slits differing only in either the width or the length may be used.

Here, the illumination optical system 12 includes a light source 40
Are formed at the front focal point of the cylindrical lenses 50a and 50b, and the cylindrical lenses 42a and 42b
cylindrical lens 50 of the field stop 44 close to b
A read original 58 is arranged on the image plane a, b. In this case, the cylindrical lens 50 of the light source 40
Since the images a and 50b can be formed at infinity, there is an effect that illumination unevenness does not occur. Further, by placing the field stop 44 on a surface close to the cylindrical lenses 42a and 42b, there is an advantage that the outline of the field stop 44 becomes clear.

On the other hand, a cover glass 54 and a support glass 56 made of a nanoglare glass for holding an original 58 to be read.
Since the image of the light source 40 is formed at infinity by the illumination optical system 12, the unevenness can be made inconspicuous even at a high magnification. As described above, by applying the illumination optical system 12 including the Koehler illumination optical system to the read document 58 using the nanglare glass, it is possible to obtain a good image without roughness.

Next, the position adjusting mechanism 14 of the illumination optical system 12 in the reading section 10 is fixed to a fixed plate 66 on the substrate 16 in proximity to the illumination optical system 12. A field stop 44 is connected to an upper portion of one end of a driving plate 70 disposed below the fixed plate 66, and a slider 74 having a roller portion 72 at an upper end portion is connected to an upper portion of the other end of the driving plate 70. Has been fixed. The driving plate 70 includes a spring 76
Through the wall portion 78 of the fixing plate 66.

On the other hand, in the flat portion of the fixing plate 66, an opening 68 from which a roller portion 72 connected to the slider 74 protrudes.
Is defined. As shown in FIGS. 2 and 3, a pair of bearing portions 80a facing each other
80b is fixed, and the opposed bearing portions 80a, 80b
Two guide shafts 82a and 82b are supported substantially parallel between them. The guide shafts 82a and 82b are inserted into the slider 74 via linear ball bearings 84a and 84b.

A slider 7 is provided on the upper surface of the fixed plate 66.
An eccentric cam 86, whose outer peripheral surface is in sliding contact with the roller portion 72 protruding upward from the upper part 4, is provided via a shaft portion 88, and a gear 90 is supported by the shaft portion 88 coaxially with the eccentric cam 86. A bracket 92 is fixed to the fixed plate 66, and a pulse motor 94 is provided on an upper surface of the bracket 92. The drive shaft of the pulse motor 94 is provided with the gear 9.
A pinion 96 that meshes with 0 is connected.

Here, the adjusting screws 36a and 36b will be described. As shown in FIG.
a is screwed into the side wall 32b of the base plate 18, and the knob 98a
Is rotated, the tip of the adjusting screw 36a contacts the side wall 34b of the substrate 16. That is, by rotating the knob 98a of the adjusting screw 36a, the substrate 16 is pressed in the direction of arrow D via the side wall 34b. As a result, the screw member 21a, the screw member 21a, the screw member 21a, which engages with the long hole 19a, 19b defined in the board 16 with the pin member 17 as a fulcrum.
1b can be displaced in the direction of arrow A (see FIG. 1). On the other hand, the tip of the other adjustment screw 36b is screwed into the side wall 34b of the substrate 16, and
It is loosely fitted into a hole 99 defined in the side wall 32b of the base plate 18. That is, when the knob 98b of the adjusting screw 36b is rotated, the substrate 16 acts so as to be pulled in the direction of the arrow E, and as a result, the substrate 16 can be displaced in the direction of the arrow B. Thus, the pair of adjustment screws 36
By rotating and adjusting the knobs 98a and 98b of the a and 36b respectively, the substrate 16 is moved in the horizontal plane by the arrow A.
Alternatively, it can be rocked and displaced in the B direction and fixed at a predetermined position.

On the other hand, the adjusting screws 22a and 22b have the same configuration as the adjusting screws 36a and 36b, and
Is adjusted in the vertical plane. Further, among the adjusting screws 38a to 38c provided on the side wall 34a of the substrate 16 facing the adjusting screws 36a and 36b, the adjusting screws 38a and 38c are the adjusting screws 36a and 38c.
The adjusting screw 38b is formed substantially the same as the adjusting screw 36b, and the illumination optical system 12 can be displaced in the direction of arrow C and fixed at a predetermined position.

The image reading apparatus according to the embodiment of the present invention is basically configured as described above, and the operation will be described next.

First, at the time of initial setting, the read original 58
Adjustment screws 36a and 36b provided on the side wall 32b of the base plate 18 in order to make the linearized light from the light source 40 through the light source 40 parallel to the linear light receiving surface of the line sensor 62 in the horizontal plane. The substrate 16 is adjusted by swinging and displacing the substrate 16 in the direction of the arrow A or B with the pin member 17 as a fulcrum.
In addition, by adjusting respective adjusting screws 22a and 22b provided near the four corners of the base plate 18, the base plate 18 is moved to the horizontal surface plate 20.
In a vertical plane. Further, the substrate 1
The casing 24 of the illumination optical system 12 is displaced in the direction of arrow C along the elongated hole 30 by three adjusting screws 38a to 38c provided on the side wall portion 34a of the scanner 6, and the light transmitted through the read original 58 is detected by the line sensor. The line is aligned with the light receiving surface 62. In this case, the illumination optical system 12 is displaced and positioned at a position where the output value of the line sensor 62 becomes maximum. Thus, the base plate 18 and the substrate 16 are adjusted by the adjusting screws 22a, 22b, 36a, 36b and 38a to 38c.
Are parallel in the vertical plane and the horizontal plane, respectively, and are fixed. As a result, the light linearized by the illumination optical system 12 erected on the substrate 16 is set to coincide with the linear light receiving surface of the line sensor 62.

Next, the operation for changing the optical magnification of an image after the initial setting as described above will be described with reference to the flowchart shown in FIG.

First, the condenser lens 60 and the line sensor 62 are moved to set a desired optical magnification (step S).
1, S2). As shown in FIG. 2, the setting is performed by moving the condenser lens 60 and the line sensor 62 via moving means (not shown) along the optical axis direction. Next, the field stop 44 is set to a slit width and a length corresponding to the optical magnification (step S3). The setting of the slit width and the like includes a plurality of slits 64a defined in the field stop 44,
64b.

That is, the driving of the pulse motor 94 causes the pinion 96 supported by the pulse motor 94 to rotate, and the pinion 96 is rotated based on the rotation of the pinion 96.
The gear 90 meshing with the gear 90 rotates, and the eccentric cam 86 connected to the gear 90 rotates. The eccentric cam 86 comes into sliding contact with a roller portion 72 provided above the slider 74, and the rotation of the eccentric cam 86 displaces the slider 74 in the direction of arrow C (see FIG. 3). Accordingly, the driving plate 70 is displaced in the direction of arrow C with the displacement of the slider 74. A field stop 44 having a slit 64a is connected to one end of the drive plate 70, and the field stop 44 itself is displaced with the displacement of the drive plate 70.

As a result, a desired slit 64a can be selected (for example, FIG. 2 shows a state where the slit 64a is selected). For example, FIG. 6 is a graph showing the relationship between the rotation angle of the eccentric cam 86 by the pulse motor 94 and the radius. Therefore, when the rotation angle of the eccentric cam 86 is set in the range G, the slit 46a is selected. Similarly, when the rotation angle of the eccentric cam 86 is set in the range F, the slit 4a is set.
6b will be selected.

Here, a slit 46 having a desired field stop width is used.
When a is set on the optical axis, the axis of the light transmitted through the slit 46a is slightly displaced from the optical axis.
There is a case where a band of light obtained by condensing the image light transmitted through 8 is displaced from the linear light receiving surface of the line sensor 62.

Therefore, after setting the slit 46a, the amount of light incident on the light receiving surface of the line sensor 62 is measured (step S4). Next, the position adjusting mechanism 14 is operated to move the field stop 44 in the direction of arrow C (step S5). The movement of the field stop 44 and the measurement of the amount of light are performed by deriving a signal from a control device (not shown) to the pulse motor 94 to drive the pulse motor 94 and to feed the drive plate 70 stepwise.

In this way, the step feed of the drive plate 70 is repeated a specified number of times (step S6), and
4 is displaced in the direction of arrow C. Next, the light amount distribution is obtained from the output signal level of the line sensor 62, and the maximum position of the light amount incident on the light receiving surface of the line sensor 62 is determined from the light amount distribution by a control device (not shown). The control device derives a signal to the pulse motor 94 and moves the field stop 44 to the maximum position of the light amount (step S7).

As described above, the slit 46a having the illumination width corresponding to the change in the optical magnification is selected, and the slit 46a is selected.
Even if a is slightly deviated from the optical axis direction, the entire original field stop 44 is moved in accordance with the optical axis of the condenser lens 60 so that the optical axis coincides with the original, thereby transmitting the read original 58 and forming a linear shape. The converted light can be incident on the linear light receiving surface of the line sensor 62.

Next, FIG. 7 shows a second embodiment relating to the reading section 100 of the image reading apparatus. In the following embodiments, the same components as those in the previous embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, the field stop 44 is directly in contact with the eccentric cam 86 via the roller 104 without displacing the field stop 44 via the driving plate 70 as in the previous embodiment. different. The eccentric cam 86 is supported by the base 106 via a shaft 108. Thereby, the structure of the reading unit 100 can be simplified,
There are advantages that the number of components can be reduced to reduce costs, and that the reading unit 100 can be configured more compactly. The field stop 102
Are rollers 110a to 1 having a groove having a substantially V-shaped cross section.
A plurality of slits 64a, 64b supported by 10d and having different slit widths and lengths are defined (see FIG. 8).

Next, a third embodiment relating to the reading section 112 of the image reading apparatus is shown in FIG.

In this embodiment, the casing 116 of the illumination optical system 114 is bent, and a mirror 118 is provided at the bent portion. Therefore, the slit 120a provided in the field stop 119 by the eccentric cam 86 supported by the pulse motor 94,
120b is selected, and the light from the light source passing through the slit 120a is reflected by the mirror 118 and can pass through the filter 46, the aperture stop 48 and the like. This is useful when the height direction of the illumination optical system 114 is restricted, and the position adjustment mechanism can be configured more compactly.

Next, another embodiment of the field stop is shown in FIGS. In the field stop 122 according to the present embodiment, the racks 127a and 127b formed on the two U-shaped stop plates 124 and 125 mesh with the gears 126a and 126b without providing a plurality of slits in the field stop 122. The slit width L of the slit 128 is configured to be variable by adjusting the width of the slit 128 (see FIG. 11). The gears 126a and 126b are fixed to, for example, the casing side of the illumination optical system, and the gears 126a and 126b are rotated by pressing one diaphragm plate 125 via a plate 129, and the other diaphragm plate 124
Can be displaced, and the diaphragm plate 125 can be displaced.
Is formed so as to be able to return via a coil spring 130. Therefore, by adjusting the width between the diaphragm plates 124 and 125 to set a predetermined slit width L and then displacing the gears 126a and 126b via a moving means (not shown) without rotating the field diaphragm, It is possible to move the entire 122 to the right side in FIG. 12 or the left side in FIG. 13 to perform line alignment with the line sensor. The aperture stop 132 has substantially the same configuration as the aperture stop 122. As shown in FIG. 14, a field stop 138 is formed by combining stop plates 134a and 134b displaced in a direction perpendicular to the line direction and stop plates 136a and 136b displaced in the line direction.
The width as well as the width of the slit 140 defined by the a, 134b, 136a, and 136b can be made variable.

[0038]

According to the image reading apparatus of the present invention, the following effects can be obtained.

That is, the position adjusting mechanism irradiates linearized light to the transmission original or the reflection original, and integrally displaces the entire field stop provided in the Koehler illumination optical system unit. Then, by the displacement of the field stop, the linear light band can be easily matched with the linear light receiving surface of the line sensor that receives light from the document. Therefore, for example, when the optical magnification of an image is changed, it is possible to easily correct a slight change in the optical axis by using the position adjustment mechanism.

The field stop has a slit having a variable width and / or length, or has a plurality of slits having different widths and / or lengths. The read original can be irradiated according to the width.

[Brief description of the drawings]

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

FIG. 2 is a partially sectional explanatory view of a reading section of the image reading apparatus.

FIG. 3 is a plan view showing a positional relationship among a field stop, a slider, and an eccentric cam.

FIG. 4 is an explanatory diagram illustrating an operation of an adjustment screw.

FIG. 5 is a flowchart showing the operation of the position adjustment mechanism when the optical magnification is changed.

FIG. 6 is an explanatory diagram showing a relationship between a radius of an eccentric cam and a rotation angle.

FIG. 7 is an explanatory partial cross-sectional view of a reading unit of an image reading apparatus according to a second embodiment of the present invention.

FIG. 8 is a perspective view showing a field stop and rollers.

FIG. 9 is a partially sectional explanatory view of a reading unit of an image reading apparatus according to a third embodiment of the present invention.

FIG. 10 is a partial sectional view showing another embodiment of the field stop and the brightness stop.

FIG. 11 is a perspective view of the field stop.

FIG. 12 is a partial sectional view showing the operation of the field stop shown in FIG.

FIG. 13 is a partial sectional view showing the operation of the field stop shown in FIG.

FIG. 14 is a plan view showing another embodiment of the field stop.

[Explanation of symbols]

10, 100, 112 Reading unit 12 Koehler illumination optical system unit 14 Position adjustment mechanism 16 Substrate 18 Base plate 40 Light source 42a, 42b, 50a, 50b Cylindrical lens 44 Field stop 46 Filter 48 Brightness Aperture 58 ... Reading document 60 ... Condenser lens 62 ... Line sensor 70 ... Drive plate 74 ... Slider 86 ... Eccentric cam 94 ... Pulse motor

Claims (4)

(57) [Claims] 1. An image reading apparatus having an optical magnification conversion mechanism and reading transmitted light or reflected light from a read original by a line sensor to obtain image information, comprising: an illumination light source; and an illumination light from the illumination light source. A first condenser lens for condensing light, a second condenser lens for guiding illumination light from the first condenser lens to a read original, and the first condenser lens and the second condenser lens. It is provided between the lens and
An illumination optical system unit including a field stop for forming a linearized image of the illumination light source on the read document; and a direction orthogonal to a line direction of the linearized image of the light source for the field stop. And a position adjusting mechanism that adjusts the position of the line sensor by displacing the line sensor to the position. 2. An apparatus according to claim 1, wherein said field stop has a slit having a variable width and / or length. 3. The image reading apparatus according to claim 1, wherein the field stop has a plurality of slits having different widths and / or lengths. 4. An image reading apparatus according to claim 1, wherein said illumination optical system is a Koehler illumination optical system.