JPH11284816A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the read speed in the case of ensuring a displacement of a solid-state image pickup element with high accuracy at a high speed and reading an original with high image quality by number of pixels of the solid- state image pickup element or over. SOLUTION: In the image reader where an original is read with high image quality by displacing a solid-state image pickup element 12 by a half pixel length, an actuator 13 supported by the solid-state image pickup element 12 is controlled by an actuator control board 22 based on a displacement curve resulting from connecting both deflection points of the solid-state image pickup element 12 with a sine curve to ensure displacement of the solid-state image pickup element 12 with high accuracy at a high speed, a sufficient storage time is ensured for a luminous quantity acting on the solid-state image pickup element 12 thereby enhancing a read speed in the case that the original is read with high image quality over number of pixels of the solid-state image pickup element 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus such as a flat bed type image scanner and a digital copying machine.

[0002]

2. Description of the Related Art Hitherto, an image reading apparatus has been used as an input method and an input device of a printer and a computer, and recently a demand for higher resolution has been increasing.

However, since a solid-state image pickup device having a high resolution and a large number of pixels is expensive, an image reading apparatus that displaces the solid-state image pickup device by a small amount to synthesize information of a plurality of image forming positions and read high-quality images has been disclosed. It has been proposed in, for example, Sho 60-16762.

Hereinafter, a conventional image reading apparatus will be described. FIG. 3 is an overall view of a conventional image reading apparatus, FIG. 4 is an explanatory diagram of a displacement operation of a conventional solid-state imaging device, FIG. 5 is a diagram of image information synthesis of the conventional solid-state imaging device, and FIG. FIG. 7 is a diagram illustrating an image sensor displacement curve, and FIG. 7 is a diagram illustrating a conventional solid-state image sensor displacement curve driven by a rectangular wave.

3 and 4, reference numeral 1 denotes a main body of the image reading apparatus, 2 denotes a document, 3 denotes a document glass on which the document 2 is loaded, 4 denotes a document pressing plate for supporting the document 2, and 5 denotes a document 6 to be described later. A frame unit 6 for supporting parts 13 to 13; an illumination unit 6 for irradiating the original 2; a wave 10; a reflecting mirror for causing reflected light emitted to the original 2 to reach an imaging lens 11 described later; Reference numeral 11 denotes an imaging lens for changing the size of the reflected light applied to the original 2 to a predetermined magnification.
Denotes a solid-state imaging device for converting an image of the document 2 formed by the imaging lens 11 into an electric signal;
This is an actuator for displacing a half pixel length.

The operation of the conventional image reading apparatus configured as described above will be described below.

First, the case where the original 2 is read with the number of pixels of the solid-state image sensor 12 will be described. The original 2 is supported on an original glass 3 by an original pressing plate 4, and an illumination unit 6
The emitted reflected light reaches the imaging lens 11 via the reflection mirrors 7 to 10. The imaging lens 11 changes the size of the reflected light at a predetermined magnification, and then forms an image on the solid-state imaging device 12.
When reading the entire document 2, the carriage frame 5 is scanned in the direction of arrow A in accordance with the length of the document 2, and the solid-state imaging device 12 is stationary without being displaced.

Next, a description will be given of the operation in the case where the original 2 is read with high image quality using the number of pixels of the solid-state image sensor 12 or more.
When reading the entire original 2 with high image quality, the solid-state image sensor 1
2 continuously vibrates the solid-state imaging device 12 in the direction of arrow B shown in FIG. 4 with a stroke of 1/2 pixel size of the solid-state imaging device 12, and the carriage frame 5 is moved in the direction of arrow A in the drawing. Scanned. At the same time, as shown in FIG. 5, the image data before and after the displacement of the displacement positions C and D of the solid-state imaging device 12 are synthesized and output as high-quality image data to the outside. The solid-state imaging device 12 is displaced by a method of driving with a sine wave shown in FIG. 6 or a method of driving with a rectangular wave shown in FIG.

[0009]

However, the configuration of the above-described conventional image reading apparatus has the following problems.

In the method of driving the solid-state imaging device 12 by a sine wave shown in FIG.
When the image data is captured in D, the image data in a portion where the image is largely displaced needs to be captured in an E portion where the displacement is relatively small because the image is unclear. Therefore, when the light amount of the illumination unit 6 cannot be increased, the light amount acting on the solid-state imaging device 12 is insufficient, and a sufficient accumulation time cannot be obtained. Therefore, it is necessary to reduce the displacement operation frequency of the solid-state imaging device 12 in order to sufficiently secure the accumulation time, and it is not possible to increase the reading speed when reading the original 2 with the number of pixels of the solid-state imaging device 12 or more with high image quality. Has problems.

In the method of driving the solid-state imaging device 12 shown in FIG. 7 with a rectangular wave, undulations indicated by broken lines occur at displacement positions C and D of the solid-state imaging device 12. It is necessary to make the displacement operation frequency of the element 12 extremely small, and there is a problem that the reading speed when reading the original 2 with the number of pixels of the solid-state imaging element 12 or more with high image quality cannot be improved. Further, when the solid-state imaging device 12 is displaced, an extremely large force is applied to the actuator 13, resulting in a loss of reliability of the actuator 13.

Therefore, the present invention solves the above-mentioned conventional problems, and displaces the solid-state image pickup device 12 at high speed and with high accuracy to sufficiently secure the accumulation time acting on the solid-state image pickup device 12 at both displacement points. It is another object of the present invention to improve the reading speed when reading the document 2 with the number of pixels of the solid-state imaging device 12 or more with high image quality and to secure the reliability of the actuator 13.

[0013]

In order to solve the above problems, an image reading apparatus according to the present invention comprises a solid-state image sensor at both displacement points by connecting and displacing both displacement points of a solid-state image sensor by a sine curve. To obtain a high-precision solid-state image sensor drive system, secure a sufficient accumulation time of the solid-state image sensor at both displacement points, and read a document with high image quality at least the number of pixels of the solid-state image sensor It is possible to provide an image reading apparatus capable of improving the reading speed in such a case.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION
A solid-state image sensor for reading a document and the solid-state image sensor
In an image reading method provided with an actuator for displacing two pixels in length, the solid-state imaging device can be settled at both displacement points by connecting and displacing both displacement points of the solid-state imaging device by a sine curve. An operation of realizing an image reading method capable of sufficiently securing an accumulation time for securing a light amount acting on the solid-state imaging device and improving a reading speed when reading a document with a number of pixels of the solid-state imaging device or more with high image quality. Having.

According to a second aspect of the present invention, there is provided an image reading apparatus according to the first aspect, wherein the actuator is a laminated piezoelectric element, wherein the tensile strength of the laminated piezoelectric element is generally low, Are connected by a sinusoidal curve and displaced to reduce the tensile force acting on the laminated piezoelectric element, thereby providing an image reading apparatus in which the reliability of the actuator is secured.

An embodiment of the present invention will be described below. FIG. 1 is a perspective view of a solid-state imaging device driving unit according to one embodiment of the present invention, and FIG. 2 is a diagram illustrating a displacement curve of the solid-state imaging device according to one embodiment of the present invention.

In FIG. 1, the operations of 12 and 13 are the same as those of the conventional image reading apparatus, and the description is omitted.
Reference numerals 5a and 5b denote solid-state image pickup device system stops for supporting the solid-state image pickup device 12 on the carriage frame 5 shown in the prior art in FIG.
14 and 15 are solid-state image sensor supporting members for supporting the solid-state image sensor 12; 16 and 17 are elastic displacement restricting members made of a plate-like elastic material and integrally formed with the solid-state image sensor supporting members 14 and 15, respectively; A U-shaped flexible printed board on which the solid-state imaging device 12 is mounted. Reference numeral 19 denotes a buffer substrate on which an input / output buffer 25 of the solid-state imaging device 12 is mainly mounted. The buffer substrate 19 is connected to a signal processing substrate (not shown) by an electric wire 20. . Reference numeral 22 denotes an actuator control board for controlling the actuator 13, which is connected by an electric wire 21.

The operation of the image reading apparatus according to an embodiment of the present invention configured as described above when reading a document 2 with high image quality by using the number of pixels of the solid-state image sensor 12 or more will be described.

When the original 2 is read at a high image quality with the number of pixels of the solid-state image sensor 12 or more, the operation of the actuator 13 supported by the solid-state image sensor 12 is reduced to 1/1/2 of the solid-state image sensor 12.
Actuator control board 2 with 2-pixel size stroke
The carriage frame 5 is scanned in the direction of the arrow A shown in FIG. 3 while vibrating in the direction of the arrow B as shown in FIG. At the same time, the image data of the solid-state imaging device 12 is transmitted to the buffer substrate 19 and transmitted to a signal processing substrate (not shown) via the electric wire 20. Solid-state imaging device 1
As shown in FIG. 2, an actuator 13 for displacing the solid-state image sensor 12 is displaced by connecting the two displacement points C and D of the solid-state imaging device 12 with a sinusoidal curve.
2, the image data before and after the displacement of the solid-state imaging device 12 sampled within the range of time G are synthesized on a signal processing board (not shown) as described in the conventional example of FIG. Emitted outside the machine.

As described above, in the embodiment of the present invention,
By connecting and displacing the two displacement points of the solid-state imaging device 12 with a sinusoidal curve, a high-precision drive system can be obtained without swelling or the like occurring at both displacement points. In addition, a sufficient accumulation time for securing the amount of light acting on the solid-state imaging device 12 can be secured, and the reading speed when reading the document 2 with the number of pixels of the solid-state imaging device 12 or more with high image quality can be improved. . Further, the tensile force applied to the actuator 13 is reduced as compared with the rectangular wave drive shown in the conventional technique of FIG. 5, and the reliability of the actuator 13 can be improved.

[0021]

As described above, according to the present invention, a high-speed and high-precision solid-state image pickup device driving system with high reliability is obtained, so that an original can be read with a high image quality by the number of pixels of the solid-state image pickup device or more. It is possible to provide an image reading apparatus that improves the reading speed in such a case.

[Brief description of the drawings]

FIG. 1 is a perspective view of a solid-state imaging device driving unit according to an embodiment of the present invention;

FIG. 2 is a diagram showing a displacement curve of the solid-state imaging device according to one embodiment of the present invention;

FIG. 3 is an overall view of a conventional image reading apparatus.

FIG. 4 is a diagram illustrating a displacement operation of a conventional solid-state imaging device.

FIG. 5 is an image information synthesis diagram of a conventional solid-state imaging device.

FIG. 6 is a diagram showing a displacement curve of a solid-state imaging device driven by a conventional sine wave drive.

FIG. 7 is a diagram showing a displacement curve of a solid-state imaging device by a conventional rectangular wave drive.

[Explanation of symbols]

 12 solid-state imaging device 13 actuator 22 actuator control board

Claims (2)

[Claims] 1. An image reading method comprising: a solid-state imaging device for reading an original; and an actuator for displacing the solid-state imaging device by a half pixel length, wherein both displacement points of the solid-state imaging device are connected by a sinusoidal curve. An image reading method, comprising: 2. The image reading apparatus according to claim 1, wherein said actuator is a laminated piezoelectric element.