JPS6276970A - Picture reader - Google Patents

Abstract

PURPOSE:To remove any influence of an abrupt variation in the quantity of light that may occur during a read scanning by correcting a picture information immediately after reading it while using a shading correction reference signal at said reading. CONSTITUTION:The reflecting lights from a first shading correction plate 3 and a second shading correction plate 5 at the time when the read scanning by a carriage 7 is started, are received by a sensor array 9, applied with photoelectric conversion, amplified, then outputted to an A/D converter 21, where they are converted to a digital signal. The resulting data is transmitted through a data transmission line 27, and is saved as a correction reference signal in a correction data part 29. The saved signals are sequentially outputted to a fixed correction arithmetic unit 31, and a correction factor to unify the sensitivities of respective elements of the sensor array 9 is calculated. The said signals go through the amplifier and the A/D converter 21, then outputted to a first arithmetic unit 35 through a data transmission line 33 as a correction signal when the picture information is inputted to the unit 35.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to a method for reading image information of a document by illuminating a document to be transmitted with light and receiving reflected light or transmitted light from the document, for example in a facsimile machine. Regarding a TGT reader.

(Technical background of the invention and its problems) In general, facsimile machines and the like use a solid-state image sensor such as a COD sensor to read the image of a document to be sent. A scanning operation in which the original is mechanically scanned, a reading operation is performed in the main scanning direction, the document is moved a predetermined distance in the sub-scanning direction perpendicular to the main scanning direction, and then the next reading operation is performed in the main scanning direction. The reading operation is performed repeatedly.

In addition, in order to read an image of a document in the main scanning direction with a sensor, light is irradiated onto the image reading position of the document, and a lens is used to reduce the image across the entire width in the main scanning direction and focus it on the sensor. Image information is sent to the sensor via a rod array lens that is disposed across the entire width in the main scanning direction, with one end facing the image reading position of the original and the other end facing the sensor. There are two types of methods: an erect, same-size contact type method that supplies images, and a serial reading method that sequentially scans and reads image information in the main scanning direction while moving the sensor in the main scanning direction. The method using a reduction optical system and the erect equal-magnification close contact type scan electronically in the main scanning direction, but the method using a reduction optical system requires a larger structure because the optical path length to the lens becomes longer. However, the erect, same-size contact type method requires the use of multiple COD sensors and has drawbacks such as being expensive, whereas the serial reading method mechanically performs scanning in the main scanning direction. However, it has the advantage of being compact and economical.

In addition, when considering a color facsimile machine as a facsimile machine, the light source for illuminating the document has superior color rendering properties compared to a tungsten lamp whose spectrum distribution is extremely close to the infrared region of 1111111M. ,
It is desirable to use a fluorescent lamp, which has various advantages such as being able to adjust the spectral distribution relatively easily by mixing the phosphor, emitting relatively little heat, and having good luminous efficiency. Furthermore, the shading correction board is I? It is a white board made of 1Epo ceramic material, and white is used as a reference for correcting read color images.

Therefore, as a color facsimile machine, a device that uses a fluorescent lamp as a light source and adopts a serial reading method in which the image information of the document is sequentially scanned and read in the main scanning direction while moving the sensor in the main scanning direction is recommended. It is superior in terms of size, economy, etc.

By the way, although fluorescent lamps have the above-mentioned advantages, they require a certain amount of time after the first 17 hours of lighting until the entire fluorescent lamp becomes stable, and the amount of light fluctuates over time due to temperature changes, etc. It also has the disadvantage that it tends to occur.

Therefore, when a fluorescent lamp with such characteristics is applied to a color facsimile machine, due to the former drawback, the document reading operation cannot be started until a predetermined time has elapsed after the facsimile start switch is operated and the fluorescent lamp starts lighting. There is a problem that it is not convenient in case of emergency.

In addition, due to the shortcomings of contact, there is a problem of deterioration of the reproduced image quality due to fluctuations in the white level due to changes in the amount of light aJ.
The conventional solution is to use a so-called shading correction plate to set the white level before starting to scan the original.However, although this solution can deal with fluctuations in light intensity due to changes over time, There is a problem in that it is not possible to deal with sudden fluctuations in the amount of light from the fluorescent lamp due to temperature changes or the like during operation.

(Objective of the Invention) This invention has been made in view of the above, and its purpose is to clearly reproduce the reproduced image without deteriorating the image quality even if the white level is unstable. !
It is an object of the present invention to provide a dual-image reading device.

(Summary of the Invention) In order to achieve the above object, the document is scanned in a first direction while irradiating the document with light using a fluorescent lamp as a light source, and reflected light or transmitted light from the document is received. In a device that reads image information of a document by moving relative to the document in a second direction perpendicular to the first direction every time reading scanning in one direction is completed, the present invention provides At the time of direction reading scanning, at least a reference signal generating means for generating a shading correction reference signal for correcting the shading of the read image due to a change in the light m of the fluorescent lamp, and a user) The gist of this invention is to provide a shading correction function (correction means that performs correction processing using a signal) from a quasi-signal generation means.

(Effects of the Invention) According to the present invention, a reference signal is generated that generates a reference signal for shedding compensation to correct image information for shading caused by fluctuations in the light amount of a fluorescent lamp even when scanning image information of a rough stone. Every time the image information is read, the image information is corrected using the shading correction reference signal of the poem, so even if a sudden change in light intensity occurs during the reading scan, this can be corrected. It is possible to obtain 1q of appropriate image information that is not affected, thereby obtaining a clear and appropriate reproduced image.

In addition, this makes it possible to obtain appropriate image information even when there is a fluctuation in the amount of light due to disturbances such as temperature changes in fluorescent lamps, and the various countermeasures to prevent fluctuations in the amount of light due to external disturbances, which were provided in conventional devices, can be obtained. This makes it unnecessary, which contributes to the miniaturization of the device, and also improves convenience by allowing image information to be read even when the amount of light from the fluorescent lamp is unstable immediately after the facsimile start switch is operated. .

(Example of the invention) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a plan view of a color facsimile machine in which an image reading apparatus according to the present invention is applied. In the figure, numeral 1 is a document in which image information to be read is written. The original 1 is held between a pair of original feeding rollers whose ends are rotatably arranged and driven to rotate by a motor (not shown), and when the rollers rotate, the original N1 is moved between the rollers. As shown in the figure, it is fed out in a sub-scanning direction perpendicular to the main-scanning direction 11, that is, a sub-scanning direction 13 in the figure. The carriage 7 houses the sensor array 9 therein so that its light receiving section faces the surface of the original 1 on which image information is written. The carriage 7 is configured to be movable in the main scanning direction 11 by a moving mechanism (not shown), and reads image information of the original 1 using a sensor array and outputs it to an amplifier and A/D converter 21, which will be described later.

A first shading correction plate 3 is provided on the left side of the original 1 in the figure. The correction plate 3 reads the reflected light from the light source as a correction reference signal at the start of the reading scan of the carriage 7 in the main scanning direction. This is to correct for variations in the Note that this correction plate 3 is a white plate made of, for example, a ceramic material.

In addition, in FIG. 1, 5 indicates a second
This second shading correction plate 5 is arranged between the original 1 and the carriage 7.
The light receiving end of the sensor array 9 is arranged in the main scanning direction 11 so as to be elongated along the width of the document 1 .

This correction plate 5 sequentially captures the light intensity fluctuations of the fluorescent lamp during the reading scan of the key This is to correct. Note that this correction plate 5 is a temporary white material made of, for example, a ceramic material.

Also, since the correction plate 5 is not in the focal plane of the sensor array 9,
Since local image noise is not received, it is less susceptible to dust, etc.

FIG. 2 is a block diagram showing the image information output processing operation according to the present invention. In the same figure, an amplifier, an A/D
The transducer 21 receives the first signal read via the sensor array 9.
Then, the correction reference signal of the second shading correction plate and the image information of the original 1 are encoded into a digital signal.

The real-time correction section 25 detects a correction reference signal for light fluctuations caused by changes over time from the second shading correction plate 5 during reading scanning of the gear ridge 7 from the amplifier and A/D converter 21. The second performance is output to the device 37. The correction data section 29 saves one correction reference word from the first and second shading correction plates at the start of the reading scan from the amplifier and A/D converter 21. The fixed correction calculation unit 31 extracts, for example, a correction factor for the light reception signal of each element to make the light reception sensitivity of each element of the sensor array 9 uniform from the correction reference signals from the two correction data parts. It is output to the first arithmetic unit 35.

The first generator 35 converts the image information of the document 1 from the amplifier and the A/D converter 21 into a light-receiving sensitivity between each element of the sensor array 9 according to the correction factor input from the fixed correction processor 31. After making corrections so that the light is received in a uniform state, the second
It is output to the computing unit 35. The second performance device 37 is
Using the correction signal input from the real-time correction calculation unit 25, the image information of the original 1 input from the first V7 unit 35 is corrected for sudden fluctuations in the amount of light in the white level, etc., and the image becomes the reproduced image. It outputs a signal 39.

Next, the operation of this embodiment will be explained.

First, the first shading correction plate 3 and the second shading correction plate 5 at the start of the reading scan of the carriage 7
After the reflected light is received by the sensor array 9 and photoelectrically converted, it is output to an amplifier and an A/D converter 21, where it is converted into a digital signal and sent via a data transmission line 27 as a correction reference signal for correction. The data is saved in the data section 29. The saved correction reference signals are sequentially sent to the fixed correction calculation unit 31.
A correction factor is calculated to equalize the light receiving sensitivity among each element of the sensor array 9, and this is used as a correction signal to transmit image information of the document 1 from the amplifier and the A/D converter 21 via the data transmission line 33. is input to the first processor 35, it is output to the first processor 35.

Next, during the reading scan of the carriage 7, the image information of the original 1 and the reflected light of the second shading correction plate 5 are
After photoelectric conversion in sensor array 9, amplifier, A/D
It is output to the converter 21 as a correction reference signal. The output correction reference signal of the second shading correction plate 5 is amplified and A/D-converted by an amplifier and an A/D converter 21, and then transmitted through a data transmission path 23 to the real I1. ? It is transmitted to the interval correction calculation section 25. The real-time correction calculation unit 25 uses the transmitted correction reference signal to calculate a correction signal for the white level with respect to the light amount fluctuation, and transmits the white level correction signal from the first calculator 35 to the second one.
When the image information of the original document 1 is output to the calculator 37, this correction signal is output to the second narrator 27.

On the other hand, the image information of the output document 1 is transmitted to the data transmission path 3.
3 to the first arithmetic unit 35, and the correction signal from the fixed correction arithmetic unit 31 corrects the image information of the document 1 based on a correction factor that makes the light receiving sensitivity of the sensor array 9 uniform. The corrected image information is sequentially sent to the second arithmetic unit 37.
is output to.

When image information is output to the second arithmetic unit 37 in this way,
A correction signal for optical fluctuations during reading scanning is inputted from the real-time correction calculating section 25, and after correcting the image information, the second correction processor 37 outputs an image signal 39 that becomes a reproduced image to the receiving side.

Such a reading operation makes it possible to obtain a reproduced image without being affected by a sudden change in the amount of light even if a sudden change in the amount of light occurs during the reading scan.

FIG. 3 shows an embodiment in which the present invention is applied to a line scanner.

As shown in FIG. 3, this line scanner is provided with a sensor array 9' having a length comparable to the width of the original 1 so as to cover the entire width of the original. This sensor array 9' is provided with linear photoelectric conversion element rows, and is driven up and down in Figure Ti1.

First and second shading correction plates are provided on the same plane as the table on which the original 1 is placed, and the first shading correction plate 3' is on the same plane as the table on which the original 1 is placed in the figure. In the figure, the second shading correction plate 5' is arranged to the left of the surface on which the original 1 is placed.

Note that the first shading correction plate 3' is approximately the same as the width of the original, and the second shading correction plate 5' is approximately the same as the height of the original.

In this configuration, the carriage 7' housing the sensor array 9 therein starts the reading operation from 1) placement opposite the first shading correction plate 3'. In this operation, a large number of charging conversion elements constituting the line sensor 9' are corrected using the ini signal 1q.

Subsequently, in a normal reading operation, that is, 13, an operation of reading the original 1, some of the photoelectric conversion elements on the left side of the carriage 7' are moved from the second shading correction plate 5'. The line scanner J3 uses this light reception signal to detect sudden fluctuations in the light intensity of fluorescent lamps due to changes in the environment during reading operations, and performs shading based on this. The specific method of this correction process is the same as that of the previous embodiment.

As described above, the present invention can be applied to serial and line type reading devices, and the specific components thereof are not limited to the above-described embodiments, and may be modified as desired without departing from the spirit of the present invention. It is possible.

[Brief explanation of drawings]

FIG. 1 is a plan view of the main parts of a color facsimile machine to which an image reading device according to an embodiment of the present invention is applied;
Figure 2 is a block diagram showing the output processing operation of the embodiment;
The figure is a plan view of an embodiment of the pond of the invention. 1... Original, 3, 3'... First shading correction plate, 5, 5'... Second shading correction plate, 7°7
'... Carriage, 9,9'... Sen 1 na array,
11...Main scanning direction, 13...Sub scanning direction, 21.
...] (1 width unit, A/D converter, 25... Actual Oh correction performance section, 29... Correction data section, 31... Fixed correction performance section, 35... No. 1 ati calculator, 37...
2nd performer, 3...image signals

Claims (2)

[Claims] (1) Scanning the original in a first direction while irradiating the original with light using a fluorescent lamp as a light source, and receiving the reflected light or transmitted light from the original, and each time the reading scan in the first direction is completed, the first In a device that reads image information of a document by moving relative to the document in a second direction perpendicular to the direction of a reference signal generating means for generating a shading correction reference signal for correcting shading caused by a change in the amount of light; and a correction means for correcting the read image information using the shading correction reference signal from the reference signal generating means. An image reading device comprising: (2) When the reference signal generating means is not performing reading scanning in the first direction, the reference signal generating means determines the density of the read image based on variations in the light reception of the light receiving section that receives reflected light or transmitted light from the document and the second direction. 2. The image reading device according to claim 1, further comprising a function of outputting a reference signal for correcting illumination variations caused by fluorescent lamps in different directions.