JPH06233078A - Image reader - Google Patents

Abstract

PURPOSE:To make a device small-sized and to increase the read rate by adjusting contact setting in the breadthwise direction of a document and the read adjustment level based on the image sensor signal of a read reference mark. CONSTITUTION:The light source of a light source is thrown to the document on a document platen glass 22, and a carriage 3 is provided movably in the subscanning direction so that the reflected light is condensed by lenses 1A and 1B having a small diameter and a short focal length through a reflection mirror 24 and is led to image sensors 2A and 2B. An outer cover 4 is provided with a read reference mark 5 which can be read by image sensors 2A and 2B at the time of initializing the carriage 3. That is, a half of an image is read by each of pairs of image sensors and lenses by reciprocation of the carriage 3, and the signal of the read reference mark 5 is read to correct the contact of data and the gradation level. Consequently, diameters of lenses and the optical path length can be shortened, and the carriage 3 is made small-sized and high-speed.

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 which can read original image data used in facsimiles, digital copying machines, scanners and the like.

[0002]

2. Description of the Related Art In recent years, image reading apparatuses, such as digital copying machines, have become widespread which are capable of digitally reading and reproducing a document with high accuracy.

A conventional image reading apparatus will be described below with reference to FIGS. 5 and 6. As shown in the figure, the light from the light source 21 is applied to the original 23 on the original table glass 22, the reflected light thereof is reflected by the reflection mirror 24, and the reflected light is condensed by the lens 25. A light source 21, a reflection mirror 24, a lens 25, and a carriage 27 in which an image sensor 26 is arranged so as to be guided to a light receiving portion of the image sensor 26 are provided so as to be movable in the sub-scanning direction of the document indicated by the arrow A. In the light receiving portion, a row of light receiving elements is arranged in the main scanning direction of the original 23, and each light receiving element is configured to output an image signal proportional to the black and white gradation of each position (each pixel) of the original 23. Was there.

The drive wire 3 engaged with the drive pulley 29 driven by the drive motor 28 and the driven pulley 30.
The position of the carriage 27 is determined by 1 and the carriage 27 is moved in the document surface scanning direction.

Further, the waiting original 23a is provided so as to be conveyed from the automatic original conveying device 32 to a predetermined position on the original table glass 22 by the conveying belt 33.
The size 3 is detected by the document size detection sensor 34.

The operation of the image reading apparatus having the above configuration will be described below. First, when the power is turned on, the carriage 27
Is moved to the reading position via the drive wire 31 by the drive of the drive motor 28. Then, the read original 23 conveyed from the automatic original conveying device 32 is conveyed by the conveying belt 33 to a predetermined position on the original table glass 22, the light from the light source 21 is applied to the original 23, and the reflected light is reflected by the lens 25. The light is collected and guided to the light receiving portion of the image sensor 26.

Next, the carriage 27 is moved in the sub-scanning direction by the drive motor 28, and the image data of the two-dimensional original 23 can be read by sequentially capturing image signals line by line.

Then, after the drive motor 28 is moved to a predetermined area corresponding to the document size obtained by the document size detection sensor 34, the drive motor 28 is reversed to return the carriage 27 to the reading start position.

Further, as shown in FIG. 6, the lens 25 and the image sensor 26 are configured to read data in the width direction of the image, and further increase the resolution represented by 400 dpi (dot per inch) or the like to realize high quality reading. In order to realize the above, the magnification of the lens 25 must be increased and the lens aperture must be increased, and the optical path length must be increased accordingly.

[0010]

In the structure of such a conventional image reading apparatus, when the resolution is increased in order to improve the quality of the read image, the image sensor 26 is used.
The number of pixels is increased, and the length of the light receiving surface of the image sensor 26 is increased. Therefore, if the width of the document 23 is constant, the magnification of the lens 25 is inevitably large, and the aperture of the lens 25 and the optical path length are large. Therefore, the size of the carriage 27 becomes large, and it becomes difficult to downsize the image reading device, so that the carriage 27 cannot be driven at high speed.

Further, as an image reading method in which a reading mark is provided to obtain an image with high resolution, Japanese Patent Laid-Open No. 208749/1987.
There was one shown in the official gazette.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an image reading apparatus of high image quality which enables downsizing of the apparatus and increase of reading speed.

[0013]

An image reading apparatus according to the present invention solves the above-mentioned problems. The invention according to claim 1 corresponds to a light source for illuminating an original, a plurality of image sensors, and this image sensor. A carriage equipped with a plurality of lenses having a small aperture and a short image formation length, and a reading reference mark provided at a position located at the reading end portion of the image sensor, and based on the image sensor signal of the reading reference mark. The contact setting in the document width direction and the reading adjustment level are adjusted.

According to a second aspect of the present invention, an A / D converter for converting an analog output of the image sensor into a digital value, a data memory for storing digital data, and an address counter for giving a drive cycle of the image sensor. ,
An adder / subtractor that gives a signal to the address counter and a CPU that controls each block are provided, and the contact of a plurality of data groups is adjusted from the address of the data memory.

[0015]

According to the present invention, due to the above-mentioned constitution, it is possible to reduce the diameter of the lens and shorten the optical path length, and it is possible to reduce the size of the carriage, the reading speed and the resolution (higher image quality). Therefore, the speed can be increased.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be described with reference to. The same parts as those of the conventional example are designated by the same reference numerals and detailed description thereof will be omitted. As shown in FIG.
The reflected light is reflected by the reflection mirror 24, and the reflected light is condensed by a plurality of lenses 1A and 1B having a small aperture and a short image formation length, and a plurality of self-scanning image sensors (a) 2A are provided. A light source 21, lenses 1A and 1B, and a carriage 3 in which the image sensors 2A and 2B are arranged so as to be guided by the image sensor (b) 2B are provided so as to be movable in the sub-scanning direction.

Further, the outer cover 4 is provided with a read reference mark 5 so that the image sensor (a) 2A and the image sensor (b) 2B can read at the beginning of the carriage 3.

In the above structure, the reciprocating operation of the carriage 3 is performed in the same manner as in the conventional example, and the image sensor (a) 2A
The lens 1A, the image sensor (b) 2B, and the lens 1B are provided as a pair inside the carriage 3, and about half the image width is read, and the signal of the reading reference mark 5 attached to the outer cover 4 is sent to the carriage 3. Initially, the image sensor (a) 2A and the image sensor (b) 2
The data is read by B, and the contact of data and the gradation level are corrected.

In addition, various types of image sensors are available, such as one in which approximately 2500 pixels each having a 7 μm square are lined up and approximately 3000 in which one pixel is 10.5 μm square are lined up. It is possible to manage the signals at the addresses corresponding to each other in order. Then, the image sensor output circuit is a sensor drive circuit 6 for driving and controlling each of the image sensor (a) 2A and the image sensor (b) 2B.
And the image sensor (a) 2A and the image sensor (b)
An address counter 7 for giving a reset pulse of a scanning start signal and a scanning clock signal to 2B, and an A / D converter 8A for converting an analog value of an output signal of the image sensor (a) 2A and an image sensor (b) 2B into a digital value. And 8B, image data memories 9A and 9B for storing data converted into digital values, an adder / subtractor 10 for performing an address, and a CPU 11 for controlling each of these blocks.
It consists of and.

The operation of the image sensor output processing circuit of FIG. 3 (b) having the above configuration will be described with reference to the flowchart of FIG. 3 (a).

First, at step 12, the carriage 3 is moved to a readable position (origin) of the read reference mark 5 by a signal from the CPU 11 and is made to stand by, and at step 13, the signal of the read reference mark 5 is sent to the image sensor (a) 2A. And the reference mark 5 read by the image sensor (b) 2B.
The image signal for one line in the main scanning direction that has been read is synchronized with the scan start signal reset pulse and the clock signal.

Then, in step 14, the data output in step 13 is converted into A / D converters 8A and 8B.
It is digitized through and is taken into the image data memories 9A and 9B, and the address is confirmed by the CPU 11. Based on the result, in step 15, the adder / subtractor 10 instructs the address counter 7 to adjust the address, and in step 16, the reading is started. The operation before and after the address adjustment of each image data memory is as shown in FIG.
The contact point of the data of the white level of the reading reference mark and the output data of the black level of the reading reference mark match after the address adjustment. Here, the data memory (b) is shown on the right for easier understanding of the case where the black and white levels are used.

There is also a method of moving the image sensor itself to match the contact points, but this method is simpler and more accurate because it requires highly accurate positioning adjustment within 10 μm per pixel. Therefore, even in the adjustment of the gradation level, the variations in the optical system (lens, image sensor, etc.) can be absorbed by making the levels of the black and white data relatively coincident.

Further, the reading of the image data of the original document is sequentially performed in this state in the sub-scanning direction (direction A). Thus, in the embodiment of the present invention, two image sensors (a)
It is possible to read the contact of the outputs of 2A and the image sensor (b) 2B with high accuracy. Further, in the embodiment, the two image sensors 2A and 2B and the two lenses 1 are used.
Although description is made using A and 1B, the same processing can be performed even when the number of image sensors and lenses is two or more, and both monochrome and color image reading devices can be used.

[0025]

As is apparent from the above description, according to the present invention, a carriage equipped with a plurality of lenses corresponding to a plurality of image sensors and a reading reference mark are provided, and an image sensor signal of the reading reference mark is used as a reference. Since the contacts are set in the document width direction and the reading adjustment level is adjusted, a wide range of resolutions can be set, the lens aperture can be reduced and the optical path length can be shortened, and the carriage can be downsized. It is possible to provide an image reading apparatus that can achieve higher speed, smaller reading apparatus, and higher resolution (higher image quality).

[Brief description of drawings]

FIG. 1A is a front view showing a schematic configuration of a carriage of an image reading apparatus according to an embodiment of the present invention. FIG. 1B is a schematic side view showing a relationship between a carriage of the image reading apparatus and a reading reference mark.

FIG. 2 is a front view showing a schematic configuration of the image reading apparatus.

FIG. 3A is a flowchart of an image sensor output processing circuit of the image reading apparatus. FIG. 3B is a block diagram of an image sensor output processing circuit of the image reading apparatus.

FIG. 4 is a schematic diagram of memory data of an image sensor of the image reading apparatus.

FIG. 5 is a side view showing a schematic configuration of a conventional image reading device.

FIG. 6A is a front view showing a schematic configuration of a carriage of the image reading apparatus. FIG. 6B is a side view showing a schematic configuration of a carriage of the image reading apparatus.

[Explanation of symbols]

 1A, 1B Lens 2A, 2B Image sensor 3 Carriage 5 Reading reference mark 7 Address counter 8A, 8B A / D converter 9A, 9B Data memory 10 Adder / subtractor 11 CPU 21 Light source 23 Original

Claims (2)

[Claims] 1. A light source for irradiating an original, a plurality of image sensors, a carriage equipped with a plurality of lenses having a small aperture and a short image forming length corresponding to the image sensors, and a reading end portion of the image sensor. An image reading apparatus having a reading reference mark provided at a position where the reading reference mark is used to perform contact setting in the document width direction and reading adjustment level adjustment based on the image sensor signal of the reading reference mark. 2. An A / D converter for converting an analog output of an image sensor into a digital value, a data memory for storing digital data, an address counter for giving a drive cycle of the image sensor, and a signal for the address counter. 2. The image reading apparatus according to claim 1, further comprising an adder / subtractor and a CPU controlling each block, and adjusting contacts of a plurality of data groups from addresses of the data memory.