JPH1155462A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the image input device of an overhead type where a scanning position of an original and a lighting position of a lighting light through a slit are made always coincident with each other and to prevent that a reflected light from the original is directly made incident on an image pickup lens. SOLUTION: A CCD line sensor 7 is contained in a sensor case 8 and the sensor case 8 is slide freely around a guide shaft 9 and along a guide groove 23 of a housing 22. The sensor case 8 is provided with a rack 11, which meshes with a lead screw 13 formed to a drive shaft of a motor 12 and the sensor case 8 is moved in a scanning direction by the drive of the motor 12. The lighting slit light is emitted onto an original by a reflecting mirror and the reflecting mirror is turned in interlocking with the movement of the CCD line sensor 7 to emit the slit light in matching with the read position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called overhead type image input device for reading a subject, for example, a document from above.

[0002]

2. Description of the Related Art Conventionally, there has been known an overhead type image input apparatus using a line type image sensor for taking in an image from a book having a thickness which cannot be read by a document feed type image input apparatus. This image input device is different from a flat head type image input device in which the reading surface is mounted upside down, and can read with high definition while the reading surface is facing upward.

FIGS. 7 to 10 show an overhead type image input apparatus using this line type image sensor.
This will be described with reference to FIG. FIG. 7 is a perspective view showing an example of a conventional overhead type image input device, and FIG. 8 and FIG.
8 is a diagram for explaining the operation of the conventional example shown in FIG.
FIG. 10 is a diagram for explaining a lighting method of the overhead type image input device.

As shown in FIG. 7, an overhead type image input device using a line type image sensor has a CCD line sensor 7, a slit light generating unit 5, and an image pickup lens 14 above a reading original 1 which is a subject. , Reflector 20
In the imaging unit composed of the above, the CCD line sensor 7 moves the imaging surface of the imaging lens 14 in the sub-scanning direction, and sequentially captures images from the reading start position 1a to the reading end position 1b of the document 1. . At this time, the slit light 2 generated by the slit light generation unit 5 is reflected by the reflecting mirror 20 which rotates in conjunction with the movement of the CCD line sensor 7 so that the original 1 which is actually read by the CCD line sensor 7 is read.
Is illuminated.

[0005] As shown in FIG. 8, the image pickup section comprises a reading and scanning mechanism 6 and a reflecting mirror rotating mechanism 15.
The reading and scanning mechanism 6 is provided with a sensor case 8 containing a CCD line sensor 7 slidably along two guide shafts 9 and 10 arranged in a horizontal direction, and is attached to the sensor case 8. The rack 11 and the lead screw 13 formed on the rotation shaft of the motor 12 are meshed. With this mechanism, the CCD line sensor 7 moves on the image forming surface of the original 1 by the imaging lens 14 in the sub-scanning direction.

The reflecting mirror rotating mechanism 15 includes a shaft 16 provided in the sensor case 8, an arm 17 for converting the horizontal movement of the shaft 16, that is, the sensor case 8 into a rotational movement,
A gear 18 provided integrally with the arm 17 at the lower end of the arm 17, a transmission gear 19 meshed with the gear 18, and a reduction gear 21 integrally attached to the side of the reflecting mirror 20 with the reflecting mirror 20. Make up. Gear 18 and reduction gear 2
The ratio between the rotation angle of the arm 17 and the rotation angle of the reflecting mirror 20 is reduced to に よ っ て by the speed reduction mechanism constituted by 1 and 2.

Next, the operation of the reflecting mirror rotating mechanism 15 will be described. As shown in FIG. 9, scanning is performed by a triangle abc formed by both ends a and b of the movement range of the shaft 16 and the rotation center c of the arm 17, the rotation center d of the reflection mirror 20, and the rotation of the reflection mirror 20. The read line 3 of the CCD line sensor 7 shown in FIG. 7 and the center line 4 of the slit light 2 coincide with each other by making the triangle def formed by both ends e and f of the scanning range of the slit light 2 similar. Let me. In this example, the rotation center d of the reflecting mirror 20 is set.
And the position of the center of view angle g of the imaging lens 14 is different.

Further, as shown in FIG. 10, in a conventional configuration in which one illumination 30 illuminates the entire main scanning direction of a document,
In order to prevent the reflected light of the irradiated light on the original surface from directly entering the imaging lens 14, the imaging lens 14 and the illumination 3
0 was set far apart.

[0009]

The above-mentioned conventional image input apparatus has the following problems.
First, the operation accuracy of a reflecting mirror rotating mechanism having a multi-stage gear configuration greatly depends on the accuracy of the gears and the accuracy of the center-to-center distance, and is greatly affected by variations in component accuracy. Also, with a multi-stage gear configuration, backlash is likely to occur, and the operation has been unstable.

In a state where the center of rotation of the reflecting mirror and the center of the angle of view of the imaging lens are apart from each other, depending on the thickness of the document,
That is, the reading position and the center of the light irradiation position are different depending on the height of the document surface, and there is a case where proper illumination cannot be performed.

Furthermore, in order to prevent reflected light from the original from directly entering the imaging lens, which is likely to occur when a glossy original is irradiated, it is necessary to greatly separate the imaging lens from the illumination. It was difficult to make the whole smaller.

[0012]

Means for Solving the Problems The present invention has been made in view of the above problems, and according to the first aspect of the present invention,
An imaging lens for reducing an image of a subject to form an image, a line-type image sensor for capturing the formed image, and moving the line-type image sensor in the sub-scanning direction along the imaging surface of the imaging lens An image input apparatus comprising: a scanning unit; a slit light generating unit that generates slit light for illuminating a shooting position of a subject; and an illumination light scanning unit that projects the slit light to a shooting position of the subject. The illumination light scanning means reflects the slit light generated by the slit light generation means toward a subject and projects the light, and rotates the reflection mirror in synchronization with the movement of the line type image sensor. A link mechanism, and further converts a movement of the line-type image sensor into a rotational movement by using a reading movement distance on an imaging surface of the line-type image sensor as a base. The triangle having the rotation center of the rotation unit as the vertex and the reading length of the subject in the sub-scanning direction as the base, and the triangle having the rotation center of the reflecting mirror as the vertex are configured to have similar shapes, and An image input device is configured in which the slit light sequentially irradiates the photographing position of the subject by the rotation of the reflecting mirror.

According to the second aspect of the present invention, the first aspect is provided.
5. The image input device according to claim 1, wherein the link mechanism is configured such that a shaft that moves integrally with the line-type image sensor, and a rotation shaft that is in contact with the shaft and that is provided at a predetermined position as the shaft moves. An arm that rotates
A guide that is in contact with the arm, rotates about a rotation axis provided at a predetermined position with the rotation of the arm, and aligns the position of the reflection surface of the reflection mirror with the center of the rotation axis to integrally form a guide; The distance from the center of the rotation axis of the arm to the contact point between the arm and the guide is equal to the distance from the center of the rotation axis of the arm to the center of the rotation axis of the guide.

According to the invention described in claim 3, according to claim 1 of the present invention,
Wherein the rotation center of the reflecting mirror is provided in a plane parallel to a main scanning line including an optical axis of the imaging lens.

According to the invention described in claim 4, according to claim 1 of the present invention,
The height of the center of rotation of the reflecting mirror and the height of the center of the angle of view of the imaging lens coincide with each other, and the center of rotation of the reflecting mirror is set to the optical axis of the imaging lens. It is provided in a plane parallel to the main scanning line.

According to the fifth aspect of the present invention, the first aspect is provided.
Wherein the two sets of the slit light generating means are arranged in the main scanning direction with the imaging lens interposed therebetween.

According to the invention described in claim 6, according to claim 1,
2. The image input device according to claim 1, wherein two sets of the slit light generating means are arranged in the main scanning direction with the imaging lens interposed therebetween, and reflected light of the slit light from a subject is directly reflected on the imaging lens. The above-mentioned problem is solved by arranging and configuring so as not to be incident on the.

In the image input apparatus according to the first aspect, it is possible to scan and read while automatically matching the image reading position on the document surface and the irradiation position of the illumination light with the movement of the line type image sensor. .

In the image input device according to the second aspect, since the movement of the line type image sensor and the rotation of the illumination reflecting mirror are synchronized via a link mechanism that does not include a gear, the image is read with high accuracy. It is possible to make the position coincide with the irradiation position of the illumination light.

In the image input device according to the third and fourth aspects, it is easy to adjust the image reading position to coincide with the irradiation position of the illumination light. Further, even if the height of the document surface is different, it is possible to scan and read while automatically matching the image reading position and the irradiation position of the illumination light with the movement of the line image sensor.

In the image input device according to the present invention, the irradiation light amount is sufficiently ensured and the light amount unevenness on the irradiation surface is reduced.

In the image input device according to the sixth aspect, the reflected light of the slit light to be irradiated from the original surface is prevented from directly entering the image pickup lens.

[0023]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a perspective view of an embodiment of an image input apparatus according to the present invention, and FIG. 2 is a perspective view of a main part thereof. 3 and 4 are views for explaining the operation of the reflecting mirror rotating mechanism of the image input device. FIG. 5 is a diagram for explaining the illumination arrangement of the image input device, and FIG. 6 is a diagram showing circuit blocks of the image input device.

FIGS. 1 and 2 show the configuration of an embodiment of the present invention. The imaging CCD line sensor 7 is housed in a sensor case 8, which is slidably provided along a guide shaft 9 and a guide groove 23 of a housing 22. The sensor case 8 includes a rack 11
Is provided, and meshes with a lead screw 13 formed on the rotation shaft of the motor 12. With this configuration, the motor 1
The rotation of the CCD line sensor 7 causes the imaging lens 1 to rotate.
4 is moved in the sub-scanning direction on the image plane, and the formed image is read.

The illumination system includes a slit light generator 5 for generating the slit light 2 for illumination, and a reflecting mirror 20 for reflecting the generated slit light 2. 24, and is provided rotatably about a rotation axis d. A link mechanism 25 for rotating the reflecting mirror 20 includes a shaft 16 provided in the sensor case 8, an arm 17 provided rotatably about a shaft 26, a guide 27 attached to a mirror holder 24, and a spring 28. It consists of

The guide 27 is slidably pressed against a shaft 29 integral with the arm 17 by the tension of the spring 28, while the opposite end of the arm 17 is slidable on the shaft 16. It is imposed.

Next, the operation of the reflecting mirror rotating mechanism of the image input device will be described. As shown in FIG.
The positional relationship between the arm 17 and the shaft 16
By making the distance between the rotation center c of the axis 26 of the mirror 26 and the rotation center d of the reflection mirror 20 and the center j of the shaft 29 equal, the rotation angle of the reflection mirror 20 becomes one of the rotation angle of the arm 17.
/ 2.

Further, the rotation angle of the reflecting mirror 20 is adjusted by the arm 17.
, The deflection angle of the emitted slit light 2 becomes the same as the rotation angle of the arm 17, and therefore, as shown in FIG.
triangle a formed by b and the rotation center c of the arm 17
c and a triangle def formed by the center of rotation d of the reflecting mirror 20 and both end positions e and f of the scanning range on the original of the slit light 2 scanned by the rotation of the reflecting mirror 20 have similar shapes. This indicates that the movement of the CCD line sensor 7 in the sub-scanning direction and the movement of the irradiation position of the slit light 2 correspond to each other. That is, when the above-described configuration is adopted, the reading line 3 by the CCD line sensor 7 shown in FIG. 1 and the center line 4 of the slit light 2 can always be made to coincide without depending on the scanning position.

In addition, the configuration is such that the axis of the rotation center d of the reflecting mirror 20 and the field angle center g of the imaging lens 14 coincide with each other. With this configuration, it is possible to make the reading line 3 coincide with the center line 4 of the slit light 2 on a plane having an arbitrary height parallel to the document surface. That is, even if the originals have different thicknesses, the scanning is performed with the reading line 3 and the center line 4 of the slit light 2 always coincident with each other.
It is possible to take an image within the depth of field of 4.
Therefore, the document surface shown in FIG.
The displacement Δl of the irradiation position due to the fluctuation of h does not occur.

In this embodiment, as shown in FIG. 5A, the reflecting mirror 20 is set in the reflecting mirror rotating mechanism having the above-described configuration, and two sets are provided on both sides of the CCD line sensor 7, and the slits are provided. The configuration is such that the reflected light of the light 2 on the document surface does not directly enter the imaging lens 14. This is to prevent a reading error from occurring when reflected light of the slit light 2 on the document surface directly enters the imaging lens 14 as shown in FIG. 5B. The imaging lens 14
A mechanism for irradiating the slit light 2 is provided on both sides of the light source to secure the illumination light amount and to reduce the light amount unevenness.

Next, the circuit configuration and operation according to this embodiment will be described. As shown in the block diagram of FIG. 6, the circuit configuration includes an operation unit 30 for inputting a scanning instruction and the like, a CPU 31 for controlling the operation of the entire apparatus, a ROM 32 in which programs and initial set values are stored, and various data. RAM 33 for temporary storage and CCD line sensor 7 for imaging
And a CCD output control unit 35 for performing various signal processing such as A / D conversion for converting an analog signal output from the CCD line sensor 7 into a digital signal, a reading / scanning motor 12, and driving the motor 12 A motor drive unit 36 for performing the operation, a light emission source drive unit 37 for lighting and driving a light emission source 38, an external input / output control unit 34 for inputting / outputting various data to / from an external device, and each unit are connected. A bus 39 is provided.

When an instruction to read a document is input by the operation unit 30, the CPU 31 drives the motor 12 via the motor driving unit 36 to move the CCD line sensor 7 to the reading start position. When the CCD line sensor 7 comes to the reading start position, the CPU 31 turns on the light emitting source 38 via the light emitting source driving unit 37, irradiates the slit light 2, and instructs the CCD output control unit 35 to perform an image reading process. I do.

The slit light 2 is reflected on the surface of the original 1,
An image is formed on the CCD line sensor 7 through the imaging lens 14. The CCD line sensor 7 supplies an output based on the received reflected light to the CCD output control unit 35.

The CCD output control unit 35 performs A / D conversion of an output signal from the CCD line sensor 7 and performs various kinds of signal processing to generate image data. Further, the CPU 31 rotates the motor 12 via the motor driving unit 36,
The sensor case 8 containing the CCD line sensor 7 is moved. In conjunction with the movement of the sensor case 8 reflector 20 rotates, the slit light 2 to the moving direction L ₁ shown in FIG. 1 of the CCD line sensor 7 moves in the opposite direction L _2.

The CCD line sensor 7 sequentially outputs an output based on the reflected light at the new reading position. The CCD output control unit 35 sequentially processes the output from the CCD line sensor 7 to generate image data. The generated image data is sequentially output to an external device via the external input / output control unit 34. Thereafter, when the reading end position is detected, the motor 12
Is stopped, the light emitting source 38 is turned off, and reading of the document is completed.

[0036]

As is apparent from the above description, according to the image input apparatus of the present invention, the shapes of the components of the image pickup section can be simplified and the number of parts can be reduced, so that an overhead type image input apparatus is provided. , While achieving smooth operation and high operation accuracy. Further, the alignment between the reading position and the slit light irradiation position can be performed accurately and easily.

Further, since the reading position and the slit light irradiation position coincide with each other on a plane having an arbitrary height parallel to the document surface, a thick document can be read within the depth of field of the lens. .

Further, it is possible to prevent the occurrence of a reading error due to the reflected light of the illumination light on the document surface directly entering the image pickup lens, which is particularly likely to occur in a glossy document.
In addition, the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of an image input device according to the present invention.

FIG. 2 is a perspective view of a main part of the image input device shown in FIG.

FIG. 3 is a diagram for explaining an operation of a reflecting mirror rotating mechanism of the image input device according to the present invention.

FIG. 4 is a diagram for explaining an operation of a reflecting mirror rotating mechanism of the image input device according to the present invention.

FIG. 5 is a diagram for explaining an illumination arrangement of the image input device according to the present invention.

FIG. 6 is a diagram showing a circuit block of the image input device according to the present invention.

FIG. 7 is a perspective view showing an example of a conventional overhead type image input device.

FIG. 8 is a diagram for explaining the operation of the image input device shown in FIG. 7;

9 is a diagram for explaining the operation of the image input device shown in FIG.

FIG. 10 is a diagram for explaining a lighting method of a conventional overhead type image input device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 original, 1 a reading start position, 1 b reading end position, 2 slit light, 3 reading line, 4 slit light center line, 5 slit light generation unit, 6 reading scanning mechanism, 7 CCD line Sensor, 8: Sensor case, 9, 10: Guide shaft, 11: Rack, 12: Motor, 13: Lead screw, 14: Imaging lens, 15
... reflecting mirror rotating mechanism, 16, 29 ... shaft, 17 ... arm, 18 ... gear, 19 ... transmission gear, 20 ... reflecting mirror, 21
... reduction gear, 22 ... housing, 23 ... guide groove, 24
... mirror holder, 25 ... link mechanism, 26 ... shaft, 27
... Guide, 28 ... Spring, 30 ... Operation unit, 31 ... CPU,
32 ROM, 33 RAM, 34 external input / output control unit, 35 CCD output control unit, 36 motor drive unit, 3
7 ... light emission source drive unit, 38 ... light emission source, 39 ... bus

Claims (6)

[Claims] An imaging lens configured to reduce an image of a subject to form an image; a line-type image sensor configured to capture the formed image; An image input device comprising: a scanning unit that moves in a scanning direction; a slit light generating unit that generates slit light for illuminating a shooting position of a subject; and an illumination light scanning unit that projects the slit light to a shooting position of the subject. The illumination light scanning means, wherein the reflecting light reflecting and projecting the slit light generated by the slit light generating means toward a subject, and the mirror in synchronization with the movement of the line type image sensor, A link mechanism for rotating a reflecting mirror, and further comprising, as a bottom, a reading movement distance on an image forming surface of the line type image sensor, and moving the line type image sensor. A triangle having a vertex at the center of rotation of the rotating means for converting into rotary motion and a triangle having a base at the reading length of the subject in the sub-scanning direction and having the vertex at the center of rotation of the reflecting mirror have similar shapes. An image input device wherein the slit light sequentially irradiates a photographing position of a subject by rotation of the reflecting mirror. 2. A link mechanism, comprising: a shaft that moves integrally with a line-type image sensor; and an arm that contacts the shaft and rotates about a rotation shaft provided at a predetermined position as the shaft moves. A guide which comes into contact with the arm, rotates about a rotation axis provided at a predetermined position with the rotation of the arm, and aligns the position of the reflection surface of the reflecting mirror with the center of the rotation axis to integrally form the guide. And a distance from the center of the rotation axis of the arm to the contact point between the arm and the guide is equal to a distance from the center of the rotation axis of the arm to the center of the rotation axis of the guide. The image input device according to claim 1, wherein a triangle is formed. 3. The image input device according to claim 1, wherein a center of rotation of said reflecting mirror is provided in a plane parallel to a main scanning line including an optical axis of said imaging lens. 4. The height of the center of rotation of the reflecting mirror and the height of the center of the angle of view of the imaging lens coincide with each other, and the center of rotation of the reflecting mirror coincides with the main scanning line including the optical axis of the imaging lens. The image input device according to claim 1, wherein the image input device is provided in a parallel plane. 5. The image input device according to claim 1, wherein two sets of said slit light generating means are arranged in a main scanning direction with said imaging lens interposed therebetween. 6. A method according to claim 1, wherein two sets of said slit light generating means are arranged in the main scanning direction with said imaging lens interposed therebetween, and reflected light of said slit light from a subject directly enters said imaging lens. It is characterized by being arranged not to be
The image input device according to claim 1.