JPH0843756A - Image scanner device - Google Patents

Abstract

PURPOSE:To make a device small in size and light in weight and to reduce assembly man-hour by providing a concave mirror forming the optical image of a subject on an image sensor and a subscanning actuator for moving the optical image of the subject in a direction perpendicular to the image sensor by moving the concave mirror. CONSTITUTION:The concave mirror 1 is arranged nearly in front of the subject 5 to face to the subject 5 in an oblique direction, and the line type image sensor 4 is arranged at a position where the image of the subject 5 by the concave mirror 1 is formed. The concave mirror 1 is supported by a concave mirror supporting mechanism 3 so that it may rotate centering around a fixed shaft, and a reflection angle by the concave mirror 1 is changed by rotating the concave mirror 1 by means of the actuator 2. The image of the subject 5 reflected from the concave mirror 1 is read by the image sensor 4, and main scanning is performed by the operation of the image sensor 4 and subscanning is performed by moving the concave mirror 1 by means of the actuator 2 so that the image of the subject 5 may be moved in the direction perpendicular to the image sensor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image scanner device for reading a still image such as a document or landscape and converting it into digital data, and more particularly to a camera type image scanner device for reading an image using a line image sensor.

[0002]

2. Description of the Related Art A two-dimensional image sensor is used as an image scanner device for reading a still image, which has a low resolution but a reading time of 1 second or less, and a line type image sensor. Although it has a drawback of requiring several tens of seconds, it has a resolution capable of reading characters. The latter image scanner uses a lens that connects the image of the object, a line-type image sensor that is placed at the position of this image, and a line for sub-scanning the image (main scanning is performed by the reading operation of the line-type image sensor itself). And a scanning mechanism for moving the mold image sensor and the like.
In the line-type image sensor, elements are arranged in one row to perform an image reading operation for each line, and there are also elements in which elements are arranged in two rows to perform an image reading operation for every two lines.

As a conventional image scanner device using a line-type image sensor in which the scanning mechanism moves the line-type image sensor, "Handy Blackboard Scanner" in Japanese Utility Model Publication No. 63-138758 and Casio Computer Co., Ltd. "Large-format quick-shooting CP-100"
There is "0". FIG. 6 shows an image scanner device of this type. In this image scanner device, an image of a subject 5 is linked by a lens 11, a line type image sensor 4 attached to a carrier 15 is arranged at the position of this image, and a guide rail 16 guides the carrier 15 and the image sensor 4 in the scanning direction. Then, the motor 13 moves the carrier 15 and the image sensor 4 in the scanning direction 17 via the speed reducer 14.

Further, there is a conventional image scanner device using a line type image sensor, which moves a reflecting mirror provided between a subject and a lens, instead of moving the image sensor for sub-scanning ( JP-A-63-48
051, "Image signal forming device", Matsushita Electric Industrial Co., Ltd. An image scanner device using this reflecting mirror will be described with reference to FIG. The light from the subject 5 is reflected by the mirror 1.
2 is reflected by lens 2 and further passes through lens 11 to lens 1
The image of the subject 5 is formed at the position of the image sensor 4 by 1. The reflector 12 is supported by the reflector support mechanism 3, and the actuator 2 rotates the reflector 12 to change the reflection angle. The line-type image sensor 4 is equivalent to one line (if the element is an array of two lines,
Each time the data of (line) is read, the reflection angle of the reflecting mirror 12 is changed to shift the position of the optical image of the subject 5 by the lens 11 with respect to the image sensor 4. By repeating this operation, sub-scanning in the direction perpendicular to the line image sensor 4 is performed. In such an image scanner device, both the reflecting mirror 12 and the lens 11 are required.

[0005]

In the image scanner device using the conventional line type image sensor described above, in the former one in which the image reading operation for each line and the parallel movement of the image sensor are repeated, the image sensor is parallelized. A guide rail to be moved, a carriage for an image sensor, a step motor as a power source, and a speed reducer are required, and the mechanism for scanning becomes complicated, and downsizing cannot be achieved. Further, in the latter case where a reflecting mirror is provided between a subject and a lens and is rotated to scan an image, both the reflecting mirror and the lens are necessary, which hinders space saving and weight reduction.

[0006]

An image scanner device of the present invention is an image scanner device in which a subject image is read by a line type image sensor and converted into an electric signal, and an optical image of the subject is formed on the image sensor. A concave-convex mirror and a sub-scanning actuator for moving the concave mirror to move the optical image of the subject in a direction perpendicular to the image sensor are provided.

[0007]

Next, the present invention will be described with reference to the drawings.

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

The concave-convex mirror 1 is placed almost in front of the subject 5.
A line-type image sensor 4 is provided at a position that is obliquely arranged with respect to the concave mirror 1 and an image of the subject 5 is formed by the concave mirror 1. The concave mirror 1 is supported by a concave mirror support mechanism 3 so as to rotate about a fixed axis, and the actuator 2 rotates the concave mirror 1 to change the reflection angle by the concave mirror 1. The image of the subject 5 reflected from the concave mirror 1 is read by the image sensor 4, main scanning is performed by the operation of the line-type image sensor 4, and sub-scanning is performed by moving the concave mirror 1 by the actuator 2 to the image sensor 4 of the subject 5. Move in a direction perpendicular to the direction.

As an example of the distance relationship of each element, the subject 5
400 mm from the image to the concave mirror 1 and 30 mm from the concave mirror 1 to the image sensor 4, and the rotation angle of the concave mirror 1 was about 20.4 °. C as the image sensor 4
CD image sensor (for example, upD manufactured by NEC Corporation)
3733) is used. This sensor consists of a 2088-bit photo cell array and a 1044-bit 2-column CCD charge transfer register. When an external control clock is input, a signal corresponding to the image formed on the sensor surface is output.

The size of the concave mirror 1 is related to the brightness of the image. The larger the concave mirror 1, the brighter the image, and the shorter the time required for the image sensor 4 to convert the image into an electric signal. In this embodiment, the concave mirror 1 has a diameter of 15 mm and a length of 40 m.
with a focal length of m.

The rotation angle of the concave mirror 1 during scanning in this embodiment will be described with reference to FIG. In this embodiment, an A4 size document, which is the subject 5 placed 400 mm away from the concave mirror 1 having a focal length of 40 mm, has a size of about 250 DPI (dot).
Design to read with / inch). Of the A4 size, the side of 210 mm is read in the line array direction of the image sensor, and the side of 297 mm is scanned by the rotation of the concave mirror 1. The angle 7 connecting both ends of the side of the original 297 mm and the center of the concave mirror 1 is 2 × arctan (297/2/400) = approximately 40.73 [degrees] [1], and the symmetry line 8 of the concave mirror 1 is defined by this angle. If the image sensor 4 is rotated by ½ of 7, the entire image can be read from the edge of the subject 5.

40.73 / 2 = 20.4 [degrees] [2] The rotation angle of the symmetry line 8 is equal to the scanning angle 6, that is, the concave mirror 1
Is rotated by about 20.4 ° shown in the equation [2], and the entire surface of the subject 5 is scanned. During this period, the signals are controlled so that the image signals for 3000 lines are received from the image sensor 4. The image sensor 4 is about 56.6 m from the concave mirror 1.
The image formed by the lens effect of the concave mirror 1 placed at m is converted into an electric signal.

In order to sequentially read images in the scanning direction, there are two methods of rotating the concave mirror 1 stepwise according to the array of the image sensor 4 or continuously moving it. When the time for reading all the images is short, for example, about 3 seconds, in the step operation of changing the reflection angle of the concave mirror 1, the stop operation and the movement are repeated 3000 times during this 3 seconds (in this embodiment, the rotation movement causes the angle of 20.7). / 30
00 [degree]) is repeated, and highly accurate control is required. Therefore, the movement of the concave mirror 1 is performed at a constant speed, and the reading control of the image sensor 4 is performed line by line at constant time intervals, or A rotation position detection mechanism is provided and a control signal is sent to the image sensor 4 at each position where reading is required to read line by line.

Further, as an actuator for moving the concave mirror, a speed reducer 10 composed of a motor 9 and a worm gear as shown in FIG. 3 may be used, and such a structure makes the motor inexpensive due to mass production effect. However, it is easy because a very small and lightweight motor is commercially available due to technological advances related to magnets. Further, as shown in FIG. 4, a piezoelectric element 18 utilizing a piezoelectric effect or an electrostrictive effect may be used as an actuator. Since the displacement of the piezoelectric element is delicate, the displacement necessary for the scanning of the present invention can be realized without using a speed reducer.

In the embodiment shown in FIG. 1, the concave mirror 1 is moved only by the rotational movement. However, only by such rotational movement, the distance from the end of the subject 5 to the concave mirror 1 is from the center of the subject 5 to the concave mirror 1. Since the concave mirror 1 projects the subject 5 onto the line-type image sensor 4, the image from the edge of the subject 5 becomes smaller than the image from the center of the subject 5, and the entire subject 5 is rectangular. However, the image read by the image sensor 4 is distorted into a barrel shape.
Such distortion can be prevented by rotating and moving the concave mirror 1 as shown in FIG. FIG. 5 shows the concave mirror 1b when reflecting light from the center b of the subject 5 and the concave mirrors 1a and 1c when reflecting light from both ends a and c of the subject. The distance from the subject 5 to the concave mirror 1 is small at both ends a and c, and large at the center b. In this way, the position of the concave mirror is moved while rotating it so that the reflection angle changes from 1a → 1b → 1c, and the image of any position of the subject 5 is always at a constant magnification (the size of the figure on the subject 5 and the concave mirror of the drawing). The ratio of the size of the image on the image sensor 4 according to 1) is projected on the image sensor 4 to reduce the possibility that the rectangle drawn on the subject 5 is read by the image sensor 4 as a barrel-distorted image. You can

[0017]

According to the present invention, the concave mirror is provided with two functions of a lens function for forming an optical image and a reflecting mirror for moving the optical image, so that the concave mirror is provided between the subject and the line image sensor. The lens can be eliminated, and the image scanner device can be made smaller and lighter, and the number of assembling steps can be reduced.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram illustrating a rotation angle of a concave mirror used in the embodiment of FIG.

3 is a perspective view showing a specific example of an actuator 2 for moving the concave mirror 1 of the embodiment of FIG.

FIG. 4 is a perspective view showing another specific example of the actuator 2 for moving the concave mirror 1 of the embodiment of FIG.

FIG. 5 is an explanatory view illustrating how to move the concave mirror 1 according to another embodiment of the present invention.

FIG. 6 is a perspective view of a conventional image scanner device.

FIG. 7 is a perspective view of another conventional image scanner device.

[Explanation of symbols]

 1 Concave Mirror 2 Actuator 3 Concave Mirror Support Mechanism 4 Image Sensor 5 Object 6 Scanning Angle 7 Angle 8 Symmetrical Line 9, 13 Motor 11 Lens 12 Reflector 10, 14 Speed Reducer 15 Carrier 16 Guide Rail 17 Scanning Direction 18 Piezoelectric Element

Claims (4)

[Claims] 1. An image scanner device for reading a subject image with a line type image sensor and converting the subject image into an electric signal. A concave-convex mirror for forming an optical image of the subject on the image sensor and a concave mirror for moving the subject. An image scanner device comprising a sub-scanning actuator for moving an optical image in a direction perpendicular to the image sensor. 2. The image scanner device according to claim 1, wherein the concave mirror rotates about a fixed axis to move an optical image of a subject. 3. The image scanner apparatus according to claim 1, wherein the concave mirror rotates and moves so as to project an optical image of a figure at any position of the subject onto the image sensor at a constant magnification. 4. The image scanner device according to claim 2, wherein the actuator comprises a piezoelectric element.