JPH05276321A - Picture reader - Google Patents

Abstract

PURPOSE:To simply make a position of a linear light receiving face of a line sensor reading a picture light coincident with a maximum luminous quantity position of a line-shaped illumination light on a line and to adjust the width to be a proper illumination width. CONSTITUTION:A Kohler illumination optical system unit 12 being an integration of a Kohler illumination optical system is formed, and a field iris 44 arranged in the unit 12 is displaced in the direction of the arrow C via a drive plate 70 under the drive of a pulse motor 94. For example, when a deviation of an optical axis takes place in a condenser lens 60 by varying an optical magnification, the field iris 44 of the unit 12 is displaced in the direction of the arrow C interlockingly with respect to a light receiving face of a line sensor 62 reading a picture light from a read original 58 to make a light strip formed to be a line by the unit 12 coincident with a linear light receiving face of the line sensor 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plane scanning type image reading apparatus which illuminates a transmission type original or a reflection type original with illumination light from a Koehler illumination optical system unit and reads the obtained image light with a line sensor.

[0002]

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

The image reading optical system in such an image reading apparatus, for example, narrows down the illumination light emitted from the illumination light source as light linearized by a slit member or the like,
The read original is irradiated, 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 avoid the flare and guide the light to the light receiving surface (usually 7 to 10 μm in width) of the very narrow line sensor, it is necessary to linearize the light for irradiating the read document with a slit member or the like.

By the way, in the case of such a configuration, the linearized light may not be accurately guided to the line sensor. In particular, line sensor, condenser lens,
This tends to occur when a transparent original or the like is moved in the optical axis direction to change the optical magnification of the image. This is because, for example, when the condenser lens is moved in the optical axis direction, an inevitable minute displacement occurs in the condenser lens. When the condenser lens is displaced, the linear sensor does not exactly match the linear band of light obtained from the read document with respect to the light-receiving surface of the line sensor. Therefore, the line sensor can read accurate image information. However, as a result, the image may be deteriorated or only part of the image information may be obtained.

Therefore, the present applicant controls the position adjusting mechanism of the slit and the position adjusting mechanism of the slit to match the line connecting the maximum light amount position of the linearized illumination light and the position of the line sensor. A slit positioning device provided with a means is 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 proposal, and is an illumination optical system having no illumination unevenness as means for linearizing light emitted from a light source, for example, Koehler. Magnification conversion operation by a magnification conversion mechanism of the image reading device, which employs an illumination optical system, is arranged in the Koehler illumination optical system, and uses a field diaphragm that forms an image of a linearized light source for illumination on a read document. Provided is an image reading device capable of easily matching the maximum light amount position of illumination light linearized corresponding to the light receiving surface of a line sensor for reading image light by displacing and adjusting the position corresponding to The purpose is to do.

Further, according to the present invention, the magnification of the image reading apparatus is defined by defining a slit having a variable width, a length, etc. in the field stop, or by forming a plurality of slits having different widths, lengths, etc. An object of the present invention is to provide an image reading device capable of providing an illumination width according to the optical magnification of the 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 that condenses the illumination light from the illumination light source, and a second condenser lens that guides the illumination light from the first condenser lens to a read document. And an illumination optical system that is provided between the first condenser lens and the second condenser lens and includes a field diaphragm that forms an image of the linearized light source for illumination on the read document. A unit and a position adjusting mechanism for performing position adjustment with respect to the line sensor by displacing the field stop in a direction orthogonal to a line direction of an image of the linearized illumination light source. ..

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

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

Furthermore, the illumination optical system is a Koehler illumination optical system.

[0012]

In the above-mentioned 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 for which the entire field stop is linearized through the position adjusting mechanism is formed. The position of the line sensor is adjusted by displacing it in the direction orthogonal to the line direction.
The width of the slit defined in the field stop and /
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 the Koehler illumination optical system as the illumination optical system, an image of the illumination light source that is linear and has no illumination unevenness is formed.

[0013]

The preferred embodiments of the image reading apparatus according to the present invention will now be described in detail with reference to the accompanying drawings.

In FIGS. 1 and 2, a Koehler illumination optical system unit (hereinafter, simply referred to as an illumination optical system) 12 constituting a reading unit 10 of an image reading apparatus and the illumination optical system 1 are shown.
The second position adjusting mechanism 14 is arranged on the base plate 18 via the 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 and 22b. Positioning pins 23a and 23b for attaching the base plate 18 to the horizontal surface plate 20 are provided at substantially central portions of both ends of the base plate 18. The board 16 is arranged on the plane of the base plate 18, and the board 16 has screw members 21a which engage with the long holes 19a and 19b defined at the other end with the pin member 17 provided at one end as a fulcrum. , 21b so as to be swingable in the direction of arrow A or B. The illumination optical system 12 is arranged in a casing 24 standing on the substrate 16. A base portion 26 is connected to a lower portion of the casing 24, and elongated holes 30 that engage with a screw member 28 are defined at both ends of the base portion 26. The casing 24 has an arrow along the elongated hole 30. It is formed to be displaceable in the C direction. In addition, side wall portions 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, side walls 34b provided in parallel with the position adjusting mechanism 14 are provided with adjusting screws 36a and 36b having substantially the same configuration as the adjusting screws 22a and 22b. On the other hand, the side wall portion 34a provided in parallel with the illumination optical system 12 is also provided with three adjusting screws 38a to 38c having substantially the same structure 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, 42 arranged below the light source 40.
b, a field stop 44 disposed below the cylindrical lenses 42a and 42b, a filter 46 and an aperture stop 48 disposed below the field stop 44, and a portion disposed below the brightness stop 48. It is provided with a pair of cylindrical lenses 50a and 50b provided. An opening 52 for allowing light to pass through is defined in the substrate 16 and the base plate 18 on which the illumination optical system 12 is erected, and the lower part of the opening 52 is made of Nungrea glass. A read manuscript 58 sandwiched between the cover glass 54 and the support glass 56 is arranged, and a condensing lens 60 for condensing the light transmitted through the read manuscript 58 and a light receiving surface for receiving the transmitted light are provided. A line sensor (for example, CCD) 62 that converts the received light into an electric signal is provided. The field stop 44 has one end connected to a drive plate, which will be described later, and has a plurality of slits 64a and 64b having different slit widths and lengths depending on the image magnification, as shown in FIG. In the present embodiment, two types of slits 64a having different widths and lengths,
Although 64b is used for the description, it goes without saying that a plurality of slits having different widths or lengths may be used.

Here, the illumination optical system 12 includes a light source 40.
Image is made at the front focal point of the cylindrical lenses 50a and 50b, and the cylindrical lenses 42a and 42b
Cylindrical lens 50 of field stop 44 close to b
The read document 58 is placed on the image plane defined by a and 50b. In this case, the cylindrical lens 50 of the light source 40
Since the images of a and 50b can be made infinite, there is an effect that uneven illumination does not occur. Further, by placing the field stop 44 on the surface close to the cylindrical lenses 42a and 42b, there is an advantage that the contour of the field stop 44 becomes clear.

On the other hand, a cover glass 54 and a supporting glass 56 made of Nungraer glass for holding the read original 58.
Since the image of the light source 40 is formed at infinity by the illumination optical system 12, the irregularities can be made inconspicuous even at high magnification. As described above, by applying the illumination optical system 12 including the Koehler illumination optical system to the read document 58 using Nungrea 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 unit 10 is fixed to the fixing plate 66 on the substrate 16 in the vicinity of the illumination optical system 12. A field stop 44 is connected to an upper portion of one end of a drive plate 70 disposed below the fixed plate 66, and a slider 74 having a roller portion 72 at its upper end is attached to the other end of the drive plate 70. Is fixed. The drive plate 70 has a spring 76.
It is pulled to the wall portion 78 of the fixing plate 66 via the.

On the other hand, an opening 68 through which the roller portion 72 connected to the slider 74 projects is formed in the plane portion of the fixed plate 66.
Is defined. As shown in FIGS. 2 and 3, a pair of bearing portions 80a facing each other are provided under the fixed plate 66, respectively.
80b is fixed, and the bearing portions 80a, 80b facing each other are provided.
Two guide shafts 82a and 82b are supported in parallel therebetween. 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, the outer peripheral surface of which is in sliding contact with the roller portion 72 projecting above 4, is provided via a shaft portion 88, and a gear 90 is axially supported by the shaft portion 88 coaxially with the eccentric cam 86. A bracket 92 is fixedly mounted on the fixed plate 66, and a pulse motor 94 is disposed on the upper surface of the bracket 92. The drive shaft of the pulse motor 94 has the gear 9
A pinion 96 that meshes with 0 is connected.

Now, the adjusting screws 36a and 36b will be described. As shown in FIG. 4, one adjustment screw 36
a is screwed into the side wall portion 32b of the base plate 18, and the knob portion 98a
When is rotated, the tip end portion of the adjusting screw 36a comes into contact with the side wall portion 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 members 21a, 2 which engage the board 16 with the elongated holes 19a, 19b defined in the board 16 with the pin member 17 as a fulcrum.
It can be oscillated and displaced in the direction of arrow A via 1b (see FIG. 1). On the other hand, the tip end portion of the other adjusting screw 36b is screwed into the side wall portion 34b of the board 16, and
The base plate 18 is loosely fitted in the hole 99 defined in the side wall 32b. That is, when the knob 98b of the adjusting screw 36b is rotated, it acts so as to pull the substrate 16 in the arrow E direction, and as a result, the substrate 16 can be oscillated and displaced in the arrow B direction. In this way, the pair of adjustment screws 36
By rotating and adjusting the knob portions 98a and 98b of a and 36b, respectively, the substrate 16 is moved in the horizontal plane by the arrow A.
Alternatively, it can be pivotally displaced in the B direction and fixed at a predetermined position.

On the other hand, the adjusting screws 22a and 22b are constructed similarly to the adjusting screws 36a and 36b, and the horizontal surface plate 20
The base plate 18 is adjusted in the vertical plane. Further, among the adjusting screws 38a to 38c provided on the side wall portion 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 to be substantially the same as the a, and the adjusting screw 38b is formed to be substantially the same as the adjusting screw 36b, and the illumination optical system 12 can be displaced in the direction of the arrow C and fixed at a predetermined position.

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

First, at the time of initial setting, the read original 58
The adjustment screws 36a and 36b provided on the side wall portion 32b of the base plate 18 are provided in order to make the linearized light transmitted from the light source 40 parallel to the linear light receiving surface of the line sensor 62 in the horizontal plane. Via the pin member 17, the substrate 16 is oscillated in the direction of arrow A or B for adjustment.
In addition, the adjustment screws 22a and 22b provided near the four corners of the base plate 18 are adjusted to move the base plate 18 to the horizontal surface plate 20.
Parallel to the vertical plane. Furthermore, 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 the three adjusting screws 38a to 38c provided on the side wall portion 34a of the reference numeral 6, and the light transmitted through the read document 58 is detected by the line sensor. The line is aligned with the light receiving surface of 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 is maximized. Thus, the adjustment screws 22a, 22b, 36a, 36b, and 38a to 38c are used to adjust the base plate 18 and the substrate 16.
Are made parallel in the vertical plane and in the horizontal plane, and are fixed. As a result, the light linearized by the illumination optical system 12 erected on the substrate 16 is set so as to match the linear light receiving surface of the line sensor 62.

Next, an operation for changing the optical magnification of an image after performing 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 along the optical axis direction via a moving unit (not shown). Next, the field stop 44 is set to have the slit width and length according to the optical magnification (step S3). The slit width and the like are set by a plurality of slits 64a defined in the field stop 44,
64b is selected and performed.

That is, by driving the pulse motor 94, the pinion 96 pivotally supported by the pulse motor 94 rotates, and based on the rotation of the pinion 96, the pinion 96.
The gear 90 that meshes with the gear 90 rotates, and the eccentric cam 86 connected to the gear 90 rotates. The eccentric cam 86 is in sliding contact with the roller portion 72 provided on the upper portion of the slider 74, and the rotation of the eccentric cam 86 causes the slider 74 to be displaced in the direction of arrow C (see FIG. 3). Therefore, the drive 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 as the drive plate 70 is displaced.

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

Here, a slit 46 having a desired field stop width is provided.
When a is set on the optical axis, the axis of the light transmitted through the slit 46a is slightly deviated from the optical axis, and the read document 5
The band of light that collects the image light that has passed through 8 may be 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 step-feed the drive plate 70.

In this way, the step feed of the drive plate 70 is repeated a designated number of times (step S6), and the field stop 4
4 is displaced in the direction of arrow C. Then, the light quantity distribution is obtained from the output signal level of the line sensor 62, and the maximum light quantity position of the light incident on the light receiving surface of the line sensor 62 is determined from the light quantity 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 of the optical magnification is selected, and the slit 46a is selected.
Even when a is slightly deviated from the optical axis direction, by moving the entire field stop 44 in accordance with the optical axis of the condenser lens 60 and aligning the optical axes, the read original 58 is transmitted and linear. The converted light can be incident on the linear light receiving surface of the line sensor 62.

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

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

Next, FIG. 9 shows a third embodiment relating to the reading unit 112 of the image reading apparatus.

In this embodiment, the casing 116 of the illumination optical system 114 is bent, and the mirror 118 is arranged at the bent portion. Therefore, the slit 120a provided in the field stop 119 by the eccentric cam 86 pivotally supported by the pulse motor 94,
Light from the light source that passes through the slit 120a when 120b is selected can be reflected by the mirror 118 and passed 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 limited, and the position adjustment mechanism can be made more compact.

Next, another embodiment of the field stop is shown in FIGS. In the field stop 122 according to this embodiment, racks 127a and 127b formed on two U-shaped stop plates 124 and 125 are meshed with gears 126a and 126b without providing the field stop 122 with a plurality of slits. The slit width L of the slit 128 is variably configured by combining them and adjusting the sandwiching width between them (see FIG. 11). The gears 126a and 126b are fixed to, for example, the casing side of the illumination optical system, and the one diaphragm plate 125 is pressed via the plate 129 to rotate the gears 126a and 126b and the other diaphragm plate 124.
And the diaphragm plate 125 can be displaced.
Are formed to be returnable via a coil spring 130. Therefore, if the width between the diaphragm plates 124 and 125 is adjusted to set a predetermined slit width L and then the gears 126a and 126b are displaced through a moving means (not shown) without being rotated, the field diaphragm can be obtained. It is possible to move the entire 122 to the right side of FIG. 12 or the left side of FIG. 13 to perform line alignment for the line sensor. The aperture stop 132 has substantially the same structure as the field stop 122. Also, as shown in FIG. 14, a field diaphragm 138 is configured by combining diaphragm plates 134a and 134b that are displaced in a direction orthogonal to the line direction and diaphragm plates 136a and 136b that are displaced in the line direction.
Not only the width but also the length of the slit 140 defined by 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 the transparent original or the reflective original with linearized light to integrally displace the entire field stop provided in the Koehler illumination optical system unit. Then, by displacing the field stop, the linear band of light 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 the image is changed, by using the position adjusting mechanism, it becomes possible to easily correct a slight shift of the optical axis.

Further, since the field stop has a slit whose width and / or length is variable, or has a plurality of slits having different widths and / or lengths, an appropriate illumination according to the optical magnification is obtained. The read original can be illuminated depending on the width.

[Brief description of 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 partial cross-sectional explanatory view of a reading unit of the image reading apparatus.

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

FIG. 4 is an explanatory diagram illustrating the operation of the adjusting screw.

FIG. 5 is a flowchart showing the operation of the position adjusting 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 a partial cross-sectional explanatory view of a reading unit of the image reading apparatus according to the second embodiment of the present invention.

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

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

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

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

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

13 is a partial cross-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 adjusting mechanism 16 ... Substrate 18 ... Base plate 40 ... Light source 42a, 42b, 50a, 50b ... Cylindrical lens 44 ... Field stop 46 ... Filter 48 ... Brightness Diaphragm 58 ... Read original 60 ... Condenser lens 62 ... Line sensor 70 ... Drive plate 74 ... Slider 86 ... Eccentric cam 94 ... Pulse motor

Claims (4)

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