JPH08274955A - Image scanner - Google Patents

Abstract

PURPOSE: To provide an image scanner in which barrel distortion is eliminated and read speed is increased. CONSTITUTION: A zoom lens 2 forms the image of a reflected light subjected to optical path conversion by a reflection mirror 4 to a linear image sensor 1. An actuator 5 conducts subscanning moving a read line 8 in a direction of the arrow B by rotating the reflecting mirror 4 in a direction of the arrow A. The linear image sensor 1 converts the received and reflected light into an electric signal and transfers the signal to a signal processing section 6 as a linear image. A zoom controller 3 connects to the zoom lens 2 to control the magnification of the lens 2 for the subscanning period while receiving an external command. The signal processing section 6 is connected electrically to the linear image sensor 1 and synthesizes the electric signal outputted from the linear image sensor 1 into a desired 2-dimension image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image scanner, and more particularly to an image scanner which reads characters and images and converts them into digital data.

[0002]

2. Description of the Related Art Conventional image scanners that have been widely sold on the market include a flatbed type image scanner in which an original is placed on a transparent plate and an image sensor scans the underside of the transparent plate, and a device is placed on the original surface of a user's hand. A typical device is a hand-held image scanner that scans an image sensor by using an indirect image scanner that reads a document indirectly by placing a distance between the document and the image scanner.

Among them, the indirect type image scanner can read a manuscript with unevenness, a thick book, and even a vertically mounted object such as a whiteboard. The size and orientation of the indirect image scanner are larger than those of other image scanners. The advantage is that there are few restrictions on the subject such as flatness.

Most of the indirect image scanners use a one-dimensional image sensor as an image-electrical signal conversion element, and in order to read a two-dimensional image, the one-dimensional image sensor has a main scanning direction and a one-dimensional direction. The image sensor is combined with a sub-scanning operation perpendicular to the longitudinal direction.

Two methods are generally used as the sub-scanning method. One is to form an image to be read on the element of the image sensor by a lens, and the one-dimensional image sensor moves in parallel within this image forming plane to perform sub scanning. The other is to provide sub-scanning by providing a reflecting mirror between the image and the lens to the one-dimensional image sensor, and rotating the reflecting mirror to change the reflection angle.

FIG. 8 is a block diagram showing an example of a conventional image scanner. This conventional image scanner has a housing 31.
A one-dimensional image sensor 32, a sub-scanning mechanism 33 for moving the one-dimensional image sensor 32 in the sub-scanning direction X, a flip-up screen 34, a mirror 35, a lens 36 arranged below the mirror 35, and a finder 37 are built-in. And lens 3
The window 38 is formed below the window 6. The original 4 is placed at a distance from the indirect image scanner.
0 is arranged.

The one-dimensional image sensor 32 is a sensor in which a plurality of light receiving elements for reading are integrated in an array. The lens 36 is provided on the surface of the one-dimensional image sensor 32 so as to form an image of the document 40 which is a subject. The sub-scanning mechanism 33 includes the one-dimensional image sensor 3
This is a mechanism for sequentially scanning the image of the two-dimensional read document 40 in the sub-scanning direction X by changing the projection position with respect to 2.

To confirm the range of the subject, frosted glass capable of flipping up is provided as a flip-up screen 34 on the surface scanned by the one-dimensional image sensor 32, and the subject image projected on the screen is reflected by a mirror 35, This is done by the user looking through the finder 37 on the device. Therefore, the user moves the image scanner or the manuscript 40 while looking at the projected image reflected on the mirror 35 and reads the range 41.
Position is adjusted, and an instruction to start reading is given to the image scanner after the adjustment is completed.

FIG. 9 is a block diagram showing another example of the conventional image scanner. This conventional image scanner has 1
The dimensional image sensor 45, the lens 46, the reflecting mirror 47, and the sub-scanning mechanism 48 are respectively provided in a casing (not shown), and the casing is fixed at a predetermined height position on the read document 49 by an arm or the like.

In this conventional image scanner, the light from the image on the read original 49 is reflected by the reflecting mirror 47 to change the optical path, and the reflected light is condensed by the condenser lens 46, and the one-dimensional image sensor 45 is formed. The reflecting mirror 47 is configured to form an image.
The sub-scanning mechanism 48 reciprocally rotates about the rotation axis in the longitudinal direction to perform sub-scanning.

[0011]

However, in the conventional image scanner for moving the one-dimensional image sensor shown in FIG. 8 in parallel, in order to move the one-dimensional image sensor 32, an image is formed by the lens 36 and the entire reading range 41 is obtained. The image sensor 32 needs a space for sub-scanning, and when the image sensor 32 is heavy, it is difficult to move quickly because vibrations occur due to the movement.

On the other hand, in the conventional image scanner for performing sub-scanning by rotating the reflecting mirror 47 shown in FIG. 9, the portion moving with the sub-scanning needs to be the reflecting mirror 47 which is relatively lightweight, and On the other hand, as shown in FIG. 10, the optical path length L between the reflecting mirror 47 and the read original 49 changes with the rotation of the reflecting mirror 47, as a result, as shown in FIG. The image of the long portion is small and the image of the short optical path is large, so that the input image has a barrel shape as shown in FIG.

Further, as a method of removing this so-called "barrel distortion", the condenser lens 46 and the image sensor 45 are moved according to the rotation angle of the reflecting mirror 47 to reach the image sensor 45 from the read original 49. A method for keeping the optical path length constant is known in the past (Japanese Patent Laid-Open No. 62-29).
1259). However, in this conventional method, since the image sensor is moved in parallel to the condenser lens, vibration is likely to occur due to the change of the center of gravity of the mechanism part due to the movement, and it is difficult to increase the reading speed without affecting the image quality. Is.

The present invention has been made in view of the above points,
It is an object of the present invention to provide an image scanner capable of removing barrel distortion and increasing reading speed.

[0015]

In order to achieve the above object, the present invention provides a one-dimensional image sensor for photoelectrically converting incident light to obtain a partial image, and a reflected light from a read original in the direction of the one-dimensional image sensor. To the optical path conversion, an actuator for rotating the reflective mirror in the sub-scanning direction, a zoom lens for focusing the light reflected by the reflective mirror on a one-dimensional image sensor, and a zoom lens for the zoom lens during the sub-scanning period by the actuator. The zoom controller is configured to change the magnification to a desired value.

Further, the zoom controller has a memory in which the magnification of the zoom lens corresponding to the rotational position of the reflecting mirror by the actuator is calculated in advance and stored, and a magnification read from the memory based on a drive signal from the actuator. Or a counter for counting the reading start signal from the one-dimensional image sensor, a magnification conversion means for converting the count value of the counter into the magnification of the zoom lens, and a magnification control means. It is characterized in that it is configured by a lens control means for variably controlling the magnification of the zoom lens according to the magnification input from the conversion means.

Further, the actuator of the present invention has a means for measuring the rotation angle of the reflecting mirror, and inputs the result of the rotation angle of the reflecting mirror measured by the measuring means to the zoom controller to adjust the magnification of the zoom lens by the zoom controller. It is characterized by setting.

Further, in order to achieve the above object, the present invention is an optical path length sensor for measuring an optical optical path length from a reading line of a reading original to a one-dimensional image sensor through a reflecting mirror and a zoom lens, or a zoom lens. Light splitting means for splitting a part of the reflected light incident on the light source, and the distance to the reading line is measured by the reflected light entering from the light splitting means. From the measurement result, the one-dimensional image sensor to the reading line is measured. An optical path length sensor for calculating the optical path length is provided, the optical path length calculated by the optical path length sensor is input to the zoom controller, and the zoom controller controls the magnification of the zoom lens so that the optical path length is constant. It is a thing.

[0019]

In the system in which the reflecting mirror is rotated and the two-dimensional image is sub-scanned by the one-dimensional image sensor, the optical path length from the original to be read to the image sensor changes, and the optical path length is longer than that of the one-dimensional image sensor. Image is small, and the image of the part with a short optical path length is large. Therefore, it is possible to correct the size of an image to be formed by using the zoom lens and changing the magnification of the zoom lens according to the difference in the optical path length during the sub-scanning period.

Further, when the position of the image scanner with respect to the read original is known in advance, the difference in optical path length is such that the magnification to be corrected according to the sub-scanning scanning order is known. By storing the value in the memory, the magnification of the zoom lens can be variably controlled according to the magnification read from the memory by the lens control unit, so that the size of the image formed can be appropriately corrected.

Further, the magnification of the zoom lens necessary for removing the "barrel distortion" is known from the number of lines scanned by the sub-scan, so the number of scanning lines is counted by the counter, and the count value is converted into the magnification. It is possible to appropriately correct the size of the image formed by converting the magnification into a magnification and variably controlling the magnification of the zoom lens.

Further, since the magnification of the zoom lens necessary for removing the "barrel distortion" is known also from the degree of rotation of the reflecting mirror due to the sub-scanning, the result of the rotating angle of the reflecting mirror is input to the zoom controller. By setting the magnification of the zoom lens by the zoom controller, the size of the image formed can be appropriately corrected.

Further, by actually detecting the optical optical path length from the reading line of the read document to the one-dimensional image sensor, or the optical optical path length from the position before entering the zoom lens to the reading line. Even if the position of the image scanner with respect to the read document is not known in advance, the magnification of the zoom lens is controlled so that the optical path length is constant, so that the size of the image formed is appropriately corrected. be able to.

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a first embodiment of the present invention. As shown in the figure, this embodiment comprises a one-dimensional image sensor 1, a zoom lens 2, a zoom controller 3, a reflecting mirror 4, an actuator 5, a signal processing unit 6 and a read original 7. A reflecting mirror 4 is provided above the read original 7, and a zoom lens 2 is provided between the reflecting mirror 4 and the one-dimensional image sensor 1.
Is provided. The reflecting mirror 4 changes the optical path of the reflected light from the reading line 8 on the reading original 7 in the direction of the zoom lens 2, and is rotationally driven by the actuator 5 to perform sub scanning.

The zoom lens 2 forms an image on the one-dimensional image sensor 1 of the reflected light whose optical path has been changed by the reflecting mirror 4. The actuator 5 rotates the reflecting mirror 4 in the direction of arrow A to move the reading line 8 in the direction of arrow B to perform sub-scanning. The one-dimensional image sensor 1 converts the reflected light that has been input into an electric signal, and forms a one-dimensional image in the signal processing unit 6
Transfer to. A zoom controller 3 is connected to the zoom lens 2 and receives a command value from the outside to control the magnification of the zoom lens 2 during the sub-scanning period. A signal processing unit 6 is electrically connected to the one-dimensional image sensor 1,
It has a function of synthesizing an electric signal output from the three-dimensional image sensor 1 into a desired two-dimensional image and converting it into a signal to be sent to a display device, a printing device, or a device that stores the image.

Next, the operation of reading an image by the image sensor 1 will be described. As a preparatory step, the reflection angle is adjusted so that the end of the original document 7 is read by the reflecting mirror 4 as a reading line and projected onto the one-dimensional image sensor 1. I'll do it. Further, the magnification of the zoom lens 2 has a width of 1 in the main scanning direction.
The magnification is adjusted in advance so that it can be read by the two-dimensional image sensor 1.

When the reading is started, the reflecting mirror 4 is rotated by the actuator 5 as a sub-scanning operation, and
The reading line 8 projected on the three-dimensional image sensor 1 moves in the direction of arrow B. At the same time, the magnification of the zoom lens 2 is also changed by receiving the magnification command value from the zoom controller 3. The one-dimensional image sensor 1 is the image sensor 1
The reading line image formed on the upper side is generated as an electric signal corresponding to a one-dimensional image and sequentially transferred to the signal processing unit 6. The signal processing unit 6 synthesizes the transferred partial images of the one-dimensional reading line to generate a two-dimensional image corresponding to the read original 7.

As the one-dimensional image sensor 1, for example, a μPD3733 manufactured by NEC Corporation having a 2088-bit CCD (charge transfer device) array element is used. When the number of arrays of the one-dimensional image sensor 1 is 2088 bits and the reading drive is repeated 3000 times,
A two-dimensional image of 2088 × 3000 pixels is obtained.

In this embodiment, as the actuator 5 of the sub-scanning mechanism, a mechanism in which a stepping motor and a speed reducing mechanism are combined is used. This stepping motor has an outer diameter of about 30 mm and a step angle of 0.72 degrees. The speed reduction mechanism has a speed reduction ratio of 100: 1. With the actuator 5 having this configuration, the reflecting mirror 4 is rotationally driven with an angular resolution of 0.0072 degrees.
The reading drive of the one-dimensional image sensor 1 may be performed by constant sampling or may be synchronized with the drive pulse of the stepping motor.

As an example of another actuator 5 of the sub-scanning mechanism, a voice coil motor (VCM) is used to form the reflecting mirror 4.
, And the rotational angle of the reflecting mirror 4 is measured by an optical pickup, and the speed of the VCM is controlled by the measurement result to drive the reflecting mirror 4 to rotate at a constant speed.
You may use the well-known reflective surface rotation means described in Japanese Patent Publication No. 079. The measurable rotational angle resolution of the above optical pickup is about 0.007 degree. The reading drive of the one-dimensional image sensor 1 may be performed by constant sampling,
It may be made to correspond to the rotation angle of the reflecting mirror 4 measured by the optical pickup.

As the reflecting mirror 4, one having a size of 40 mm (rotational axis direction) × 30 mm is used. The zoom lens 2 has a magnification range of 1.0 to 1.2 and a focal length of 55 m.
I am using m. The zoom controller 3 connected to the zoom lens 2 controls the magnification value so as to correct the size of the image caused by the change in the optical path length from the read original 7 to the one-dimensional image sensor 1 during the sub-scanning period. . The optical path length from the read original 7 to the one-dimensional image sensor 1 can be shown as a function of the rotation angle of the reflecting mirror 4.

Next, the relationship between the rotation angle and the optical path length will be described using mathematical expressions. The size of the scanned document 7 is A4,
The center of the reflecting mirror 4 is located directly above the center of the original, the rotation axis of the reflecting mirror 4 is at a height h [mm] from the reading original 7, and scanning is performed in the long side direction of the A4 original 297 mm long. The case will be described as an example. FIG. 2 is a side view of the reflecting mirror 4 and the read original 7.

When sub-scanning an A4 size original in the long side direction,
The rotation angle θ of the reflecting mirror 4 depends on the center of the reflecting mirror 4 and the zoom lens 2.
Based on the optical axis connecting the centers of

[0034]

[Equation 1] Becomes However,

[0035]

[Equation 2] Assuming that the optical path length from the reflecting mirror 4 to the read original 7 when the rotation angle is θ is L [mm], the angle θ ′ is calculated by the following equation from FIG.

[0036]

(Equation 3) Therefore, at the rotation angle θ of the reflecting mirror 4 in FIG. 2, the angle φ formed by the perpendicular line from the center of the reflecting mirror 4 to the reading original 7 and the line segment connecting the end of the reading original 7 and the reading line of x mm Is expressed by the following equation using the equation (3).

[0037]

[Equation 4] Therefore, the above optical path length L is expressed by the following equation using the equation (4).

[0038]

(Equation 5) The magnification z (θ) given to the zoom lens 2 by the zoom controller 3 is represented by the following equation when the rotation angle of the reflecting mirror 4 is θ.

[0039]

(Equation 6) However, in the above formula, z ₀ is the magnification of when θ = θ _0/2.

By controlling the magnification of the zoom lens 2 according to the value of this magnification, "barrel distortion" can be eliminated. As an example, the reflection mirror 4
If the distance h to is 400 mm and z ₀ = 1 then the rotation angle θ changes by approximately 35 ° ≦ θ ≦ 55 ° (7). Therefore, the magnification may be controlled within the range of 1 ≦ z (θ) ≦ 1.064 (8).

The value that determines the magnification of the zoom lens 2 is calculated as described above if the positional relationship between the reflecting mirror 4 and the read document 7 is known, and the result is stored in the memory in advance and By controlling the magnification of the zoom lens 2 according to the value output from the memory during the scanning period, "barrel distortion" can be removed.

FIG. 3 shows a block diagram of an example of the zoom controller 3 for controlling the magnification of the zoom lens 2 using a memory. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals, and their description will be omitted. In FIG. 3, the zoom controller 3 reads out the lens control means 11 for controlling the zoom lens 2 to adjust the magnification and the set magnification of the zoom lens 2 corresponding to the drive of the actuator 5 are calculated in advance and stored. It is composed of a read only memory (ROM) 12 which is a kind of dedicated memory.

When the sub-scan of the image scanner is started in the zoom controller 3, the lens control means 11 reads out the desired magnification of the zoom lens 2 from the ROM 12 based on the drive signal transferred from the actuator 5 and reads it. The barrel distortion is removed by controlling the magnification of the zoom lens 2 according to the output value.

Further, a counter for counting the number of lines scanned by sub-scanning is provided, and the magnification of the zoom lens 2 is controlled in accordance with the output value from this counter to cause "barrel distortion".
Can also be removed. FIG. 4 shows another example of the zoom controller 3 having this configuration. As shown in FIG. 4, the zoom controller 3 includes a sub-scanning counter 1 that counts the number of readings of the one-dimensional image sensor 1, that is, the number of sub-scannings.
4, a magnification conversion unit 15 that converts the output value from the sub-scanning counter 14 into a magnification of the zoom lens 2, and a lens control unit 16 that controls the zoom lens 2 to adjust the magnification.

Next, the operation of the zoom controller 3 will be described. The sub-scanning counter 14 counts the reading start signal of the one-dimensional image sensor 1 and transfers it to the magnification conversion means 15. The magnification conversion means 15 determines the desired magnification of the zoom lens 2 based on the count value of the sub-scanning counter 14, and transfers it to the lens control means 16. The lens control means 16 controls the zoom lens 2 to set the magnification of the zoom lens 2 to the magnification sent from the magnification conversion means 15.

The magnification conversion means 15 has a calculation function of converting the magnification into a magnification by calculation in real time during the sub-scanning period.
There is a method in which a scan line number-magnification correspondence table is used in which the result of calculation is accumulated in a memory and a magnification value is extracted from the memory during the sub-scanning period. In either case, the sub-scanning counter 1
The magnification value of the zoom lens 2 is calculated from the number of sub-scans, which is the output from No. 4, and this calculation method will be described below.

[0047]

(Equation 7) If the width of the reading line is Δx [mm], then x [m
The number of sub-scanning times n when sub-scanning is performed by [m] is expressed as n = x / Δx (10). Substituting equation (10) into equation (9),
The following equation is obtained.

[0048]

(Equation 8) Accordingly, the magnification z (n) is expressed by the following equation.

[0049]

[Equation 9] By using this relationship, the magnification of the zoom lens 2 is determined from the number of sub-scans, and by controlling the magnification of the zoom lens 2, the "barrel distortion" can be removed.

It is also possible to eliminate the "barrel distortion" by providing a means for detecting the rotation angle of the reflecting mirror 4 accompanying the sub-scanning and utilizing this detection angle. Utilizing the detection result of the sub-scanning angle is, as described above, necessary for removing the “barrel distortion” and the rotation angle of the reflecting mirror 4 and the zoom lens 2.
Since the relationship with the magnification of is known, by controlling the magnification of the zoom lens 2 based on this relationship, "barrel distortion"
Can be realized.

As the means for detecting the rotation angle of the actuator 5, the reflection surface rotation angle measuring means 21 as shown in FIG.
It is possible to use a conventionally known configuration including the above and the reflecting surface rotating means 22 (Japanese Patent Laid-Open No. 6-133079).
Issue). The rotation angle detection means supplies a reflection mirror rotation angle signal indicating the reflection surface rotation angle measured by the reflection surface rotation angle measurement means 21 to the zoom controller 3 to control the magnification of the zoom lens 2 and rotate the reflection surface. Means 22
The "barrel distortion" is eliminated by controlling the rotation angle of the reflecting mirror 4 supplied to the.

Furthermore, the positional relationship of the image scanner with respect to the read original 7, that is, the positional relationship between the rotation axis of the reflecting mirror 4 which rotates with the sub-scanning and the one-dimensional image sensor 1 is not fixed. Even when it changes every time when is used, removal of the “barrel distortion” can be realized by measuring the optical path length. This embodiment will be described with reference to FIG.

FIG. 6 is a block diagram of the second embodiment of the present invention. The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 6, optical path length sensors 24 and 25 for measuring the optical path length are provided on both sides of the one-dimensional image sensor 1 in the longitudinal direction. This optical path length sensor 24
From 25 and 25, the read original 7 which is determined according to the angle of the reflecting mirror 4 is passed through the zoom lens 2 and the reflecting mirror 4.
The optical path length to the read line 8 which is part of the optical path is measured. The optical optical path length referred to here is a conversion of the optical path due to refraction of the zoom lens 2 into an optical path length in the air when the zoom lens 2 is absent.

The magnification of the zoom lens 2 is controlled so that the optical optical path length outputs from the optical path length sensors 24 and 25 become constant during the sub-scanning period. That is, when the sub-scanning is started from the end of the read document 7, the optical path length is shortened at first, but at this time, the magnification of the zoom lens 2 is reduced so that the optical optical path length obtained from the optical path length sensors 24 and 25 does not change. Then, when the optical path length becomes longer, the magnification of the zoom lens 2 is controlled so as to prevent the optical path lengths obtained from the optical path length sensors 24 and 25 from changing. In this way, the optical path length sensors 24 and 25
The "barrel distortion" is eliminated by feeding back the output from the device and controlling the magnification of the zoom lens 2 so that the optical optical path length does not change.

The optical path length sensors 24 and 25 shown in FIG. 6 are of the active type in which ultrasonic waves or infrared light is output from the sensor side to the original surface and the optical path length is calculated from the reflected ultrasonic waves or infrared light. There is a passive method in which nothing is output from the sensor side and the optical path length is calculated based on the image input from the document surface.

In the embodiment of FIG. 6, an example using infrared rays is shown. The optical path length sensors 24 and 25 are infrared light emitting diodes, lenses for making the light from the light emitting diodes into a spot shape, and the read original 7. The main components are a lens that collects the light reflected back from the lens and a phototransistor that receives the collected reflected light. Of the two optical path length sensors 24 and 25 shown in FIG. 6, one is for infrared emission,
The other shows a housing for receiving infrared light. In addition, the light of the infrared light emitting diode is a circuit that frequency-modulates the intensity of the light,
The signal processing unit 6 including a circuit for calculating the phase difference between the change in the intensity of the returned reflected light and the timing of frequency modulation on the light emitting side and converting it to the optical path length is provided by the optical path length sensors 24 and 25.
It is connected to the.

In this embodiment, for example, the optical path length sensor 24
The infrared light emitted from the infrared light emitting diode therein is reflected by the reflecting mirror 4 and projected onto a position on the document surface of the read document 7 determined by the reflection angle. The projected light of the infrared light emitting diode is irregularly reflected on the surface of the original, and a part of the projected light is reflected again by the reflecting mirror 4, and returns to the phototransistor in the optical path length sensor 25 for receiving light. This optical path length changes depending on the rotation of the reflecting mirror 4 as described above,
Since the infrared light is frequency-modulated, the intensity of the infrared light received by the phototransistor is also frequency-modulated,
A phase shift occurs in vibration due to frequency modulation of light emission and light reception according to a change in optical path length. A change in optical path length is detected by detecting this phase shift angle.

By the way, in the above embodiment, the zoom lens 2 is used.
The optical path length sensors 24 and 25 are arranged so as to measure the influence of the optical path length as an optical optical path length. Occurs in one direction.

Therefore, in the third embodiment of the present invention shown in FIG. 7, the optical path length sensor 27 and the sensor mirror 28 are installed so as not to pass through the zoom lens 2, and the light necessary for measuring the optical path length is the sensor mirror. It is refracted at 28 and measured. The optical path length sensor 27 has a configuration in which the components required for infrared emission and the components required for light reception are contained in one housing.

The optical path length sensor 27 measures the distance from the reading line 8 which moves with the rotation of the reflecting mirror 4 to the optical path length sensor 27 via the reflecting mirror 4 and the sensor mirror 28 during the sub-scanning period, The actual optical path length from the one-dimensional image sensor 1 to the reading line 8 is calculated. And
The “barrel distortion” can be removed by changing the magnification of the zoom lens 2 so that the optical optical path length becomes constant according to the change of the optical path length which is the measurement result.

[0061]

As described above, according to the present invention,
Since the zoom lens is used to correct the size of the image to be formed by changing the magnification of the zoom lens according to the difference in the optical path length during the sub-scanning period, the barrel distortion caused by the difference in the optical path length is caused. Can be removed.

Further, according to the present invention, the mechanism driven by the sub-scanning is only the rotation of the reflecting mirror and the movement of the lens, and the image sensor unlike the conventional image scanner does not move in parallel. Compared with the above, it is possible to reduce the vibration due to the change of the center of gravity of the mechanism portion due to the movement and to speed up the sub-scanning, and thus it is effective in improving the image quality of the image scanner and speeding up the reading.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a rotation angle and an optical path length.

FIG. 3 is a block diagram of an example of a zoom controller.

FIG. 4 is a block diagram of another example of a zoom controller.

FIG. 5 is a block diagram of an example of an actuator.

FIG. 6 is a configuration diagram of a second embodiment of the present invention.

FIG. 7 is a configuration diagram of a third embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional example.

FIG. 9 is a configuration diagram of another conventional example.

FIG. 10 is a diagram illustrating a problem of the conventional image scanner of FIG.

FIG. 11 is a diagram illustrating a problem of the conventional image scanner of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1-dimensional image sensor 2 Zoom lens 3 Zoom controller 4 Reflector 5 Actuator 6 Signal processing unit 7 Read document 11, 16 Lens control means 12 Read only memory (ROM) 14 Sub-scanning counter 15 Magnification conversion means 21 Reflective surface rotation Angle measuring means 22 Reflecting surface rotating means 24, 25, 27 Optical path length sensor

Claims (6)

[Claims] 1. A partial image is obtained by photoelectrically converting incident light.
-Dimensional image sensor, a reflecting mirror for changing the optical path of reflected light from a read document in the direction of the one-dimensional image sensor, an actuator for rotating the reflecting mirror in the sub-scanning direction, and light reflected by the reflecting mirror. An image scanner comprising: a zoom lens that forms an image on a one-dimensional image sensor; and a zoom controller that changes a magnification of the zoom lens to a desired value during a sub-scanning period by the actuator. 2. The zoom controller includes a memory in which a magnification of the zoom lens corresponding to a rotational position of the reflecting mirror by the actuator is calculated and stored in advance, and the memory based on a drive signal from the actuator. 2. The image scanner according to claim 1, further comprising lens control means for variably controlling the magnification of the zoom lens according to the magnification read from the. 3. The zoom controller includes a counter that counts a read start signal from the one-dimensional image sensor, a magnification conversion unit that converts the count value of the counter into a magnification of the zoom lens, and the magnification conversion unit. 2. A lens control means for variably controlling the magnification of the zoom lens according to the input magnification.
Image scanner described. 4. The actuator includes a rotation angle measurement unit for the reflection mirror, and inputs the rotation angle result of the reflection mirror measured by the measurement unit to the zoom controller to zoom the zoom controller. The image scanner according to claim 1, wherein the magnification of the lens is set. 5. An optical path length sensor for measuring an optical optical path length from the reading line of the read original to the one-dimensional image sensor via the reflecting mirror and the zoom lens is provided, and the optical path measured by the optical path length sensor. A length is input to the zoom controller, the zoom controller reduces the magnification of the zoom lens when the optical path length increases with the sub-scanning operation, and the zoom lens when the optical path length decreases with the sub-scanning operation. The image scanner according to claim 1, wherein the optical path length is controlled to be constant by increasing a magnification of a lens. 6. A light splitting unit that splits a part of the reflected light that enters the zoom lens from the reading line of the read document through the reflecting mirror, and the reflected light enters from the light splitting unit. An optical path length sensor for measuring the distance to the reading line is provided, and the optical path length from the one-dimensional image sensor to the reading line is calculated from the distance measured by the optical path length sensor,
Input the calculated optical path length to the zoom controller,
The image scanner according to claim 1, wherein the zoom controller controls the magnification of the zoom lens so as to keep the optical path length constant.