JP2710211B2 - Image scanner device - 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 for reading a still image such as a document or a landscape and converting it into digital data, and more particularly to a camera type image scanner for reading an image using a line image sensor.

[0002]

2. Description of the Related Art A two-dimensional image sensor is used for an image scanner for reading a still image. A scanner having a low resolution but a reading time of 1 second or less and a line type image sensor are used. Although it has the disadvantage of requiring several tens of seconds, some have a resolution capable of reading characters. The latter image scanner has a lens for forming an image of a subject, a line-type image sensor arranged at the position of the 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 a type image sensor and the like.
Some line-type image sensors perform the image reading operation for each line by arranging the elements in one line, and some perform the image reading operation for every two lines by arranging the elements in two lines.

In a conventional image scanner using a line type image sensor, a scanning mechanism moves the line type image sensor. A "handy blackboard scanner" disclosed in Japanese Utility Model Laid-Open Publication No. 63-138758 and Casio Computer Co., Ltd. "Large Format Quick Shot CP-100"
0 ". FIG. 6 shows an image scanner of this type. In this image scanner, an image of a subject 5 is connected by a lens 11, a line type image sensor 4 attached to a carrier 15 is arranged at the position of the image, and the carrier 15 and the image sensor 4 are guided by a guide rail 16 in a scanning direction. Then, the carrier 15 and the image sensor 4 are moved in the scanning direction 17 by the motor 13 via the speed reducer 14.

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

[0005]

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

[0006]

According to the present invention, there is provided an image scanner for reading an object image by a line type image sensor and converting the image into an electric signal, wherein an optical image of the object is formed on the image sensor. A concave mirror and a sub-scanning actuator that moves the concave mirror to move an optical image of the subject in a direction perpendicular to the image sensor.

[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 mirror 1 is placed almost in front of the subject 5
And a line type image sensor 4 is provided at a position where the 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 concave mirror 1 is rotated by an actuator 2 to change the angle of reflection by the concave mirror 1. The image of the subject 5 reflected from the concave mirror 1 is read by the image sensor 4, the main scanning is performed by the operation of the line type image sensor 4, and the sub-scanning is performed by moving the concave mirror 1 by the actuator 2 to the image sensor 4 of the subject 5. It is performed by moving in a direction perpendicular to the direction.

As an example of the distance relationship between the elements, a subject 5
In the image of FIG. 5, the distance from the concave mirror 1 to the concave mirror 1 was 400 mm, the distance from the concave mirror 1 to the image sensor 4 was 30 mm, 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). This sensor comprises a 2088-bit photocell array and a 1044-bit two-column CCD charge transfer register. By inputting an external control clock, a signal corresponding to an image formed on the sensor surface is output.

The size of the concave mirror 1 is related to the brightness of the image. As the concave mirror 1 is larger, the image becomes brighter, and the time required to convert the image into an electric signal by the image sensor 4 can be shortened. In this embodiment, the concave mirror 1 has a diameter of 15 mm and a length of 40 m.
It has a focal length of m.

The rotation angle of the concave mirror 1 during scanning according to the present embodiment will be described with reference to FIG. In this embodiment, an A4 size document, which is the subject 5 placed at a distance of 400 mm from the concave mirror 1 having a focal length of 40 mm, is approximately 250 DPI (dot).
/ Inch). In the A4 size, the direction of the side of 210 mm is read in the line array direction of the image sensor, and the direction of the side of 297 mm is scanned by the rotation of the concave mirror 1. An 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) = about 40.73 [degrees] [1]. If the image sensor 4 is rotated by ７, the entire image sensor 4 can be read from the end 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 Expression [2], thereby scanning the entire surface of the subject 5. During this time, the signal is controlled so that image signals for 3000 lines are received from the image sensor 4. Image sensor 4 is approximately 56.6 m from concave mirror 1
An image formed by the lens effect of the concave mirror 1 is converted to an electric signal at the position m.

In order to sequentially read images in the scanning direction, there are two methods of rotating the concave mirror 1 in a stepwise manner according to an array of the image sensors 4 or moving the mirror continuously. If the time for reading all images is short, for example, about 3 seconds, in the step operation of changing the reflection angle of the concave mirror 1, 3000 stops and movements are performed in these 3 seconds (in this embodiment, the angle is 20.7 times by rotational movement). / 30
00 [degree]), and high-precision control is required. Therefore, the movement of the concave mirror 1 is performed at a constant speed, and reading control of the image sensor 4 is performed in line units at fixed time intervals, or A control signal is sent to the image sensor 4 for each position where reading is necessary by providing a rotation position detecting mechanism, and reading is performed for each line.

As the actuator for moving the concave mirror, a motor 9 and a speed reducer 10 composed of a worm gear or the like may be used as shown in FIG. 3, and such a configuration reduces the cost of the motor due to mass production effects. This is easy because very small and light motors are commercially available due to technological advances in 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 required for scanning according to the present invention can be realized without using a speed reducer.

The method of moving the concave mirror 1 in the embodiment shown in FIG. 1 is only a rotational movement. With only such a 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. When the concave mirror 1 projects the subject 5 onto the line-type image sensor 4, the image from the end of the subject 5 is smaller than the image from the center of the subject 5, and the entire subject 5 is rectangular. Also, the image read by the image sensor 4 is distorted in a barrel shape.
Such distortion can be prevented by rotating and moving the concave mirror 1 as shown in FIG. FIG. 5 shows a concave mirror 1b when reflecting light from the center b of the subject 5 and 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. As described above, the position of the concave mirror is also moved while rotating so as to change the reflection angle from 1a to 1b to 1c, so that the image at any position of the subject 5 is always at a fixed magnification (the size of the figure on the subject 5 and the concave mirror of the drawing). The ratio of the rectangle drawn on the object 5 to the image sensor 4 as a barrel-shaped image is reduced by projecting the image on the image sensor 4 with the ratio of the size of the image on the image sensor 4 to the size of the image sensor 4. Can be.

[0017]

According to the present invention, a concave mirror is provided with two functions of a lens function for connecting an optical image and a reflecting mirror for moving the optical image, so that it is provided between the subject and the line type image sensor. Since the lens can be eliminated, the size and weight of the image scanner can be reduced, and the number of assembling steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an image scanner 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.

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

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

FIG. 5 is an explanatory diagram illustrating a method of moving a 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]

 DESCRIPTION OF SYMBOLS 1 Concave mirror 2 Actuator 3 Concave mirror support mechanism 4 Image sensor 5 Subject 6 Scan angle 7 Angle 8 Symmetry line 9, 13 Motor 11 Lens 12 Reflector 10, 14, Reducer 15 Carrier 16 Guide rail 17 Scanning direction 18 Piezoelectric element

Claims (4)

(57) [Claims] 1. An image scanner device for reading a subject image by a line type image sensor and converting the read image into an electric signal, a concave mirror for forming an optical image of the subject on the image sensor, and an optical system of the subject by moving the concave mirror. An image scanner device comprising a sub-scanning actuator for moving an 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 the subject. 3. The image scanner device according to claim 1, wherein the concave mirror rotates and moves so that an optical image of a figure at any position of the subject is projected onto the image sensor at a fixed magnification. 4. The image scanner according to claim 2, wherein the actuator comprises a piezoelectric element.