JP2910612B2 - Image scanner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a commercially available image scanner includes a flatbed type image scanner in which an original is scanned on a transparent plate and an image sensor scans the original under the transparent plate. Representative devices include a hand-held image scanner that scans an image sensor with an image sensor, and an indirect image scanner that indirectly reads a document while keeping a distance between the document and the image scanner.

[0003] Among them, the indirect image scanner can read originals having irregularities, thick books, and even a white board or the like which is installed almost vertically, and is larger in size and orientation than other image scanners. There is an advantage that there are few restrictions on the subject such as flatness.

Many indirect image scanners use a one-dimensional image sensor as an image-to-electrical signal conversion element, in order to read a two-dimensional image, a main scanning, which is a longitudinal direction of the one-dimensional image sensor, and a one-dimensional image sensor. The image sensor combines sub-scanning operations perpendicular to the longitudinal direction.

As the sub-scanning method, two methods are generally used. One is to form an image to be read on an element of the image sensor by a lens, and the one-dimensional image sensor moves in parallel on the image forming plane to perform sub-scanning. The other is provided with a reflecting mirror from an image to a one-dimensional image sensor through a lens, and performs sub-scanning by rotating the reflecting mirror to change a 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 disposed below the mirror 35, and a finder 37 are built-in. And lens 3
6, a window 38 is formed below. Document 4 is placed at a distance from this 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 a document 40 as a subject. The sub-scanning mechanism 33 includes the one-dimensional image sensor 3
This is a mechanism for sequentially scanning the two-dimensional image of the read original 40 in the sub-scanning direction X while changing the position where the image is projected on the two.

To confirm the range of the subject, a frosted glass that can be flipped 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 here is reflected by a mirror 35, This is performed by the user looking into the finder 37 in the apparatus. Therefore, the user moves the image scanner or the original 40 while viewing the projected image reflected on the mirror 35, and reads the area 41.
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 a conventional image scanner. This conventional image scanner has 1
A three-dimensional image sensor 45, a lens 46, a reflecting mirror 47, and a sub-scanning mechanism 48 are respectively provided in a casing (not shown), and the casing is fixed at a predetermined height position on a read document 49 by an arm or the like.

In this conventional image scanner, light from an image on a read original 49 is reflected by a reflecting mirror 47 to change the optical path, and the reflected light is condensed by a condensing lens 46 to be transmitted to a one-dimensional image sensor 45. With the configuration for forming an image, the reflecting mirror 47
Is reciprocated about the longitudinal rotation axis thereof by the sub-scanning mechanism 48 to perform sub-scanning.

[0011]

However, in order to move the one-dimensional image sensor 32, the conventional image scanner shown in FIG. Requires a space for the image sensor 32 to perform sub-scanning, and when the image sensor 32 is heavy, it is difficult to move quickly because vibrations accompanying movement occur.

On the other hand, in the conventional image scanner in which the sub-scan is performed by rotating the reflecting mirror 47 shown in FIG. 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 shown in FIG. Since the image of the long part is small and the image of the short part of the optical path is large, the input image becomes barrel-shaped as shown in FIG.

As a method of removing the so-called "barrel distortion", the condensing lens 46 and the image sensor 45 are moved in accordance with the rotation angle of the reflecting mirror 47, and the distance from the read original 49 to the image sensor 45 is reduced. A method for keeping the optical path length constant has been known (Japanese Patent Laid-Open No. Sho 62-29).
1259). However, in this conventional method, since the image sensor is moved in parallel with respect to the condensing lens, vibration is likely to occur due to a change in the center of gravity of the mechanism due to the movement, and it is difficult to increase the reading speed without affecting the image quality. It is.

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

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a one-dimensional image sensor for obtaining a partial image by photoelectrically converting incident light and a one-dimensional image sensor for reflecting reflected light from a read original. A reflecting mirror that changes the optical path, an actuator that rotates the reflecting mirror in the sub-scanning direction, a zoom lens that forms an image of the light reflected by the reflecting mirror on a one-dimensional image sensor, and a zoom lens during the sub-scanning period by the actuator. And a zoom controller for changing the magnification to a desired value.

[0016]

[0017]

According to another aspect of the present invention, there is provided an optical path length sensor for measuring an optical path length from a reading line of a read original to a one-dimensional image sensor through a reflecting mirror and a zoom lens, or a zoom lens. A light branching means for branching a part of the reflected light incident on the light source, and a distance from the one-dimensional image sensor to the reading line by measuring the distance to the reading line by the reflected light being incident from the light branching means. An optical path length sensor for calculating the optical path length of the zoom lens is provided, and 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. Things.

[0019]

According to the method of rotating a reflecting mirror and sub-scanning a two-dimensional image on a 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 the one-dimensional image sensor. Is small, and the image of the portion where the optical path length is short forms a large image. Therefore, the zoom lens can be used to change the magnification of the zoom lens according to the difference in the optical path length during the sub-scanning period, thereby correcting the size of the image to be formed.

When the position of the image scanner with respect to the original to be read is known in advance as the difference in the optical path length, the magnification to be corrected in accordance with the sub-scanning order is known. By storing the values in the memory, the size of the image to be formed can be properly corrected by variably controlling the magnification of the zoom lens according to the magnification read from the memory by the lens control unit.

Further, since the magnification of the zoom lens required for removing the "barrel distortion" is known from the number of lines scanned by the sub-scanning, the number of scanning lines is counted by a counter, and the counted value is converted into a magnification. By converting the magnification into magnification by means and variably controlling the magnification of the zoom lens, it is possible to appropriately correct the size of the image to be formed.

Further, since the magnification of the zoom lens necessary for removing the "barrel distortion" is known from the degree of rotation of the reflecting mirror accompanying 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 to be formed can be properly corrected.

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

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of a first embodiment of the present invention. As shown in FIG. 1, this embodiment includes 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 reflection mirror 4 is provided above the read original 7, and a zoom lens 2 is provided between the reflection 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 rotated by an 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 and performs sub-scanning. The one-dimensional image sensor 1 converts the input reflected light into an electric signal and converts the reflected light into a one-dimensional image.
Transfer to A zoom controller 3 is connected to the zoom lens 2 and controls the magnification of the zoom lens 2 during the sub-scanning period in response to an external command value. 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 dimensional image sensor 1 into a desired two-dimensional image and converting the signal into a signal to be sent to a display device, a printing device, or a device for storing images.

Next, the operation of reading an image by the image sensor 1 will be described. As a preparatory step, the reflecting mirror 4 is read and the reflection angle is adjusted so that the end of the document 7 is projected on the one-dimensional image sensor 1 as a reading line. Keep it. Also, the magnification of the zoom lens 2 has a width of 1 in the main scanning direction.
The magnification is adjusted so as to be within the range that can be read by the dimensional image sensor 1.

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

As the one-dimensional image sensor 1, for example, μPD3733 manufactured by NEC Corporation having a 2088-bit CCD (charge transfer element) 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 combining a stepping motor and a speed reduction mechanism 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 uses a speed reduction ratio of 100: 1. The reflecting mirror 4 is rotationally driven with an angular resolution of 0.0072 degrees by the actuator 5 having this configuration.
The reading drive of the one-dimensional image sensor 1 may be performed by constant sampling, or may be synchronized with a driving pulse of a stepping motor.

As another example of the actuator 5 of the sub-scanning mechanism, the reflecting mirror 4 is driven by a voice coil motor (VCM).
Is driven in rotation and linear motion, the rotation angle of the reflecting mirror 4 is measured by an optical pickup, and the VCM is speed-controlled based on the measurement result to rotate the reflecting mirror 4 at a constant speed.
A known reflecting surface rotating means described in Japanese Patent No. 079 may be used. The rotation angle resolution that can be measured by the optical pickup is about 0.007 degrees. The reading drive of the one-dimensional image sensor 1 may be performed by constant sampling,
It may correspond to the rotation angle of the reflecting mirror 4 measured by the optical pickup.

As the reflecting mirror 4, a mirror having a size of 40 mm (rotational axis direction) × 30 mm is used. As the zoom lens 2, a magnification range of 1.0 to 1.2 and a focal length of 55 m
m. A zoom controller 3 connected to the zoom lens 2 controls a magnification value so as to correct the size of an image caused by a change in the optical path length from the read document 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 read original 7 is A4 size,
The center of the reflecting mirror 4 is located directly above the center of the document, and the rotation axis of the reflecting mirror 4 is located at a height h [mm] from the read document 7, and the A4 document is scanned in the long side direction of 297 mm in length. An example will be described. FIG. 2 is a side view of the reflection mirror 4 and the read original 7.

When sub-scanning the A4 size original in the long side direction,
The rotation angle θ of the reflecting mirror 4 is set between the center of the reflecting mirror 4 and the zoom lens 2.
With reference to 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], from FIG.

[0036]

(Equation 3) Therefore, the angle φ between the vertical line from the center of the reflecting mirror 4 to the read original 7 and the line connecting the xmm read line from the end of the read original 7 at the rotation angle θ of the reflecting mirror 4 in FIG. 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 expressed 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 in accordance with the value of the magnification, "barrel distortion" can be eliminated. As an example, the reflection mirror 4
If the distance h is 400 mm and z ₀ = 1, the rotation angle θ changes by about 35 ° ≦ θ ≦ 55 ° (7). Therefore, the magnification may be controlled within the range of 1 ≦ z (θ) ≦ 1.064 (8).

The value for determining the magnification of the zoom lens 2 is calculated as described above if the positional relationship between the reflecting mirror 4 and the read original 7 is known, and the result is stored in a memory in advance, and The “barrel distortion” can be removed by controlling the magnification of the zoom lens 2 based on the value output from the memory during the scanning period.

FIG. 3 is a block diagram showing 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 of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 3, a zoom controller 3 controls the zoom lens 2 to adjust the magnification, and a readout in which a set magnification of the zoom lens 2 corresponding to the driving of the actuator 5 is calculated and stored in advance. A read-only memory (ROM) 12, which is a kind of dedicated memory, is provided.

In the zoom controller 3, when the sub-scanning of the image scanner is started, the lens controller 11 reads the desired magnification of the zoom lens 2 from the ROM 12 based on the drive signal transferred from the actuator 5, and reads the desired magnification. 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 the sub-scanning is provided, and the magnification of the zoom lens 2 is controlled in accordance with the output value from the counter to obtain "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 means 15 for converting an output value from the sub-scanning counter 14 into a magnification of the zoom lens 2, and a lens control means 16 for controlling 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 converter 15. The magnification converter 15 determines a desired magnification of the zoom lens 2 based on the count value of the sub-scanning counter 14 and transfers the desired magnification to the lens controller 16. The lens controller 16 controls the zoom lens 2 to set the magnification of the zoom lens 2 to the magnification sent from the magnification converter 15.

The magnification conversion means 15 has a calculation function of converting the magnification into a magnification by real-time calculation during the sub-scanning period.
In some cases, a result of a previously calculated operation is stored in a memory, and during a sub-scanning period, a magnification value is retrieved from the memory using a scan line-magnification correspondence table. In any 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 the calculation method will be described below.

[0047]

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

[0048]

(Equation 8) Thus, 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 the “barrel distortion” can be removed by controlling the magnification of the zoom lens 2.

Further, a means for detecting the rotation angle of the reflecting mirror 4 associated with the sub-scanning is provided, and the "barrel distortion" can be removed by using the detected angle. As described above, the use of the detection result of the sub-scanning angle requires the rotation angle of the reflecting mirror 4 and the zoom lens 2 necessary for removing the “barrel distortion”.
Since the relationship with the magnification is known, the barrel distortion is controlled by controlling the magnification of the zoom lens 2 based on this relationship.
Removal can be realized.

As means for detecting the rotation angle of the actuator 5, a reflection surface rotation angle measuring means 21 as shown in FIG.
A configuration known in the art, consisting of a light source and a reflection surface rotating means 22, can be used (Japanese Patent Laid-Open No. Hei 6-133079).
No.). 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 to adjust the reflection surface rotation. Means 22
By controlling the rotation angle of the reflecting mirror 4 to be supplied to the lens, the “barrel distortion” is removed.

Further, the positional relationship of the image scanner with respect to the original 7 to be read, that is, the positional relationship between the one-dimensional image sensor 1 and the rotation axis of the reflecting mirror 4 rotating with the sub-scanning is not fixed. Even if it changes each time 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 a second embodiment of the present invention, in which the same components as those of FIG. 1 are denoted 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
And 25 pass through the zoom lens 2, further pass through the reflecting mirror 4, and read the original 7 determined according to the angle of the reflecting mirror 4.
The optical path length up to the reading line 8 which is a part of the optical path length is measured. Here, the optical optical path length is a value obtained by converting a change in an optical path due to refraction of the zoom lens 2 into an optical path length in air when the zoom lens 2 is not provided.

The magnification of the zoom lens 2 is controlled so that the output of the optical path length from the optical path length sensors 24 and 25 becomes constant during the sub-scanning period. That is, when the sub-scanning is started from the end of the read original 7, the optical path length becomes shorter at first, but at this time, the magnification of the zoom lens 2 is reduced so that the optical path length obtained from the optical path length sensors 24 and 25 does not change. When the optical path length becomes longer, control is performed so as to increase the magnification of the zoom lens 2 so that the optical optical path length obtained from the optical path length sensors 24 and 25 does not change. Thus, the optical path length sensors 24 and 25
By feeding back the output of the zoom lens 2 and controlling the magnification of the zoom lens 2 so that the optical path length does not change, the "barrel distortion" is eliminated.

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

The embodiment shown in FIG. 6 shows an example using infrared light. The optical path length sensors 24 and 25 include an infrared light emitting diode, a lens for making light from the light emitting diode into a spot shape, and a reading original 7. The main components are a lens that collects the light reflected and returned from the device, and a phototransistor that receives the collected reflected light. One of the two optical path length sensors 24 and 25 shown in FIG.
The other shows a housing for infrared light reception. 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 comprising 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 the same into an 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 inside is reflected by the reflecting mirror 4 and is projected onto a position on the original surface of the read original 7 determined by the reflection angle. The projected light of the infrared light emitting diode is irregularly reflected on the document surface, and part of the projected light is reflected again by the reflecting mirror 4 and returns to, for example, a phototransistor in the optical path length sensor 25 for receiving light. This optical path length changes with 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 the vibration due to the frequency modulation of the light emission and the light reception according to the change in the optical path length. By detecting the phase shift angle, the change in the optical path length is detected.

In the above embodiment, the zoom lens 2
The optical path length sensors 24 and 25 are arranged so that the influence of the optical path length is also measured. However, the change in the optical path length due to the sub-scanning when the reflecting mirror 4 is rotated causes Occur 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 reflected by the sensor mirror. Measure at 28 with refraction. The optical path length sensor 27 has a configuration in which components necessary for infrared light emission and components necessary for light reception are housed in one housing.

The optical path length sensor 27 measures the distance from the reading line 8 moving with the rotation of the reflecting mirror 4 during the sub-scanning period to the optical path length sensor 27 via the reflecting mirror 4 and the sensor mirror 28. 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 path length becomes constant according to the change in the optical path length as the measurement result.

[0061]

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

Further, according to the present invention, the mechanism driven by the sub-scan only needs to rotate the reflecting mirror and move the lens, and does not translate the image sensor like a conventional image scanner. In comparison with the above, the vibration caused by the change in the center of gravity of the mechanism unit due to the movement can be reduced, and the speed of the sub-scanning can be increased. Therefore, the image quality of the image scanner is improved and the reading speed is increased.

[Brief description of the 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 illustrating an example of a zoom controller.

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

FIG. 5 is a block diagram illustrating 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 example of the related art.

FIG. 10 is an explanatory diagram of a problem of the conventional image scanner of FIG. 9;

FIG. 11 is an explanatory diagram of a problem of the conventional image scanner of FIG. 9;

[Explanation of symbols]

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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-326835 (JP, A) JP-A-8-9109 (JP, A) JP-A-8-274956 (JP, A) JP-A-2- 14666 (JP, A) JP-A-63-37772 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 1/04-1/207

Claims (1)

(57) [Claims] 1. A partial image is obtained by photoelectrically converting incident light.
-Dimensional image sensor; a reflecting mirror that changes the optical path of reflected light from the read original in the direction of the one-dimensional image sensor; an actuator that rotates the reflecting mirror in a sub-scanning direction; and a light that is reflected by the reflecting mirror. after a zoom lens for forming the one-dimensional image sensor, a zoom controller for changing the desired value of magnification of the zoom lens in the sub scanning period by the actuator, the reflecting mirror from the read lines of the read original
To split a part of the reflected light incident on the zoom lens
Light branching means, and the reflected light is incident from the light branching means.
An optical path length sensor that measures the distance to the reading line
From the distance measured by the optical path length sensor.
Optical light from the image sensor to the reading line
A path length is calculated, and the calculated optical path length is used as the zoom control.
The optical path length by the zoom controller.
An image scanner , wherein the magnification of the zoom lens is controlled to be constant .