JPH04306053A - Picture reader - Google Patents

Abstract

PURPOSE:To improve the distortion at picture read and repetitive position accuracy at the time of picture read by eliminating a mechanical drive section of a read section with respect to the picture reader used for an image scanner, a copying machine or a facsimile equipment or the like. CONSTITUTION:The picture reader is provided with an original placing plate 1, a light source 2 irradiating an original, and an image sensor 5 receiving a reflected light from the original P, and an area type image sensor is employed for the image sensor 5 and the scanning by a conventional mechanism system is implemented electrically in the inside of the area image sensor 5. Since no mechanical drive component is in existence in this way, the vibration and uneven speed specific to the mechanism system are avoided. Moreover, even in the case of high speed reading, no excess power is required. Furthermore, since the optical system is always fixed, the position accuracy is considerably improved in comparison with a conventional method.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device, and more particularly to an image reading device used in image scanners, copying machines, facsimile machines, and the like.

0002

[Prior Art] Conventionally, image reading devices used in image scanners, digital copying machines, facsimile machines, etc. use a linear image sensor in the image reading section, and move the optical system by a drive system to scan the image line by line. is being read.

An example of the above-mentioned conventional image reading device will be described below with reference to the drawings.

In FIGS. 2 and 3, 11 is a document stand;
2 is a light source, and 13 is a reflection plate that reflects and condenses the light emitted from the light source 12 and irradiates it onto the surface of the document. 14 is a first mirror, and the light source 12, the reflection plate 13, and the first mirror 14 constitute a constant velocity section 15. 16 and 17 are the second
mirror, a third mirror, and constitutes the half-speed section 18. 19 is a lens, and 20 is a linear image sensor. 21 is a wire 23 wound around a pulley 22 by a motor.
The constant speed section 15 and the half speed section 18 are driven by this.

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

[0006] The light emitted from the light source 12 is reflected and condensed by a reflection plate 13 and illuminates the original P placed on the original table 11. The light that hits the document surface and is reflected is reflected by the first mirror 14,
A document image is guided by a second mirror 16 and a third mirror 17, and is projected and formed onto an image sensor 20 by a lens 19. At this time, the image sensor 20 reads one line of image data. Next, rotate the motor 21 and pulley 2
When the driving force is transmitted from the wire 23 to the constant velocity section 15 and the half velocity section 18 by rotating the constant velocity section 2, the constant velocity section 15 moves in the direction of arrow A and moves to the position adjacent to it by one line. At this position, the image sensor 20 further reads one line of image data. By repeating the above operations and scanning the document in the direction of arrow A by the constant velocity section 15, an image of the entire surface of the document can be read.

[0007]

[Problems to be Solved by the Invention] However, in the above configuration, the constant velocity section 15 and the half speed section 18 must be driven by the motor 21, and if the moving speed is not constant, distortion will occur in the image. there is a possibility. Furthermore, when reading an image at high speed, a motor 21 with a large torque must be used, and power consumption is also large. Furthermore, when reading a color image, it is necessary to scan the same document multiple times in order to read multiple color components, which poses a problem in the accuracy of color overlapping alignment.

In view of the above problems, the present invention aims to provide an image reading device that does not use mechanical scanning, has no image distortion, has low power consumption, and has high color overlapping positioning accuracy when reading color images. purpose.

[0009]

[Means for Solving the Problems] In order to solve the above problems, an image reading device of the present invention includes a document holder, a light source that irradiates the document, and an image sensor that receives reflected light from the document. This is an area type image sensor.

0010

[Operation] With the above-described structure, the image reading device of the present invention performs scanning electrically inside the area type image sensor, instead of scanning by a conventional mechanical system. Therefore, vibrations and speed unevenness peculiar to mechanical systems are eliminated. Furthermore, when reading at high speed, conventional methods require large power consumption and a large motor, but electrical scanning does not require excessive power. Furthermore, since the optical system is always fixed, positional accuracy can be significantly improved compared to conventional methods.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In Figure 1, 1
2 is a document stand; 2 is a light source; 3 is a reflector that reflects and condenses the light from the light source to illuminate the document efficiently and uniformly. 4 is a lens, and 5 is an area type image sensor that can read an image on a surface.

The operation of the image reading apparatus configured as described above will be explained. The light emitted by the light source 2 is reflected and focused onto the document surface by the effect of the reflection plate 3, and irradiates the document. The reflected light reflected from the document surface is imaged by the lens 4, and an image of the document is projected onto the area type image sensor 5. The projected image is read by an area type image sensor 5. The read image data becomes the output of the image reading device. At this time, since the scanning method of the area type image sensor 5 is electrical scanning, distortion of the image due to the drive of the optical system can be prevented.
Furthermore, the repeat position accuracy of images can be improved when scanning is performed a plurality of times.

As described above, according to this embodiment, by using an area type image sensor for image reading,
It is possible to obtain distortion-free images and high image repeatability. Furthermore, since there are no mechanically moving parts, the number of parts can be reduced, and since there are no mechanically moving parts, vibrations and the like are also eliminated.

[0014]

Effects of the Invention As is clear from the above description of the embodiments, according to the image reading device of the present invention, by using an area type image sensor as a reading sensor, distortion during image reading and repetition during image reading can be reduced. Position accuracy can be improved. Furthermore, by eliminating the mechanical scan, it is possible to reduce the number of parts and eliminate vibrations during operation.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the main parts of an image reading device according to an embodiment of the present invention.

[Fig. 2] A vertical cross-sectional view showing the main parts of a conventional image reading device.

[Figure 3] Rear perspective view of the image reading device

[Explanation of symbols]

1. Manuscript stand 2 Light source 4 Lens 5 Area type image sensor

Claims (1)

[Claims] [Claim 1] A document tray, a light source for illuminating the document, and an image sensor for receiving reflected light from the document;
An image reading device in which the image sensor is of an area type.