JP2001157006A - Image-reading processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To share one image processing part in external devices, such as an image reader and an image-forming device. SOLUTION: A reading control part 3 of an image reader 1 sets a light source to a turn-off state, causes an image sensor 5 to read the reflected light from a reference white board, gives instruction for acquisition of image data of the respective blocks of the image sensor 5, which are outputted from an image converter 44, to an image-forming device 2. The part 3 obtains the maximum value of image data of the respective blocks, which are detected by the image-processing part 6, calculates/adjusts the offset quantity of respective offset adjusters 42, sets the light source to a turn-on state, causes the image sensor 5 to read the reflected light from a reference whiteboard, gives the instruction for acquisition of image data of the respective blocks of the image sensor 5, which are outputted from the image converter 44, to the image-forming device 2, acquires the maximum value of image data of the respective blocks, which are detected by the image-processing part 6, and calculates/adjusts the gain quantity of respective gain amplifiers 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine comprising an image reading device and an external device such as an image forming device,
The present invention relates to an image reading processing system such as a digital multifunction peripheral and a facsimile machine.

[0002]

2. Description of the Related Art For example, as an image reading device used in a digital copying machine, a document transport device (document transport means) for transporting a document and a plurality of photoelectric conversion elements are orthogonal to a sub-scanning direction which is a document transport direction. Some include line image sensors arranged one-dimensionally in the main scanning direction.

In such an image reading apparatus, when an image reading of a document is instructed, a reading control unit conveys the document by a document conveying device and turns on a light source.
The image of the document is read by the line image sensor. At this time, each photoelectric conversion element of the line image sensor reads the reflected light from the document, converts the light into an analog signal, and outputs the analog signal in parallel.

An analog signal output from each photoelectric conversion element of the line image sensor is A / D
The data is converted into digital data by a converter (A / D conversion means) and processed as image data. When the data is converted into digital data, the data is connected to the preceding stage so as to be suitable for the resolution of the A / D converter. A gain amplifier (gain adjusting means) performs amplification (gain adjustment) of the analog signal.

[0005] In addition, at the time of dark output, since an offset component is superimposed on the analog signal output from each photoelectric conversion element of the line image sensor, an offset adjustment is required to obtain an accurate dark output level at the time of reading a document image. A device (offset adjusting means) is also provided to adjust the offset of the analog signal output from each photoelectric conversion element of the line image sensor.

An analog signal amplified by a gain amplifier and offset-adjusted by an offset adjuster is converted into digital data by an A / D converter and output as image data. Means), the data is converted into a single main scanning line in a permutation and output.

Here, the gain adjustment and offset adjustment of the analog signal will be described more specifically. Image data output from the image converter is sampled (acquired) for each photoelectric conversion element or for one main scanning line, and The gain amount (adjustment value) and the offset amount (adjustment value) are calculated based on the image data that has been subjected to image processing such as averaging processing, maximum value detection and minimum value detection, and black data subtraction correction. Perform gain adjustment and offset adjustment.

After the gain adjustment and the offset adjustment have been performed in this way, an accurate analog signal (read signal) is input to the A / D converter, where it is converted into digital data. In addition, since variations in the dark output and bright output of each photoelectric conversion element of the line image sensor and variations in the light emission amount of the light source occur, the variations are generally smoothed and corrected by performing shading correction. I have to.

As a technique for obtaining an appropriate image density by performing an appropriate offset adjustment and suppressing each variation, for example, image data of an image reading apparatus as disclosed in Japanese Patent Application Laid-Open No. 2-189073 is known. There is an adjustment method. In this image data adjustment method, the image reading device
A reference white plate used when adjusting the image density is provided, and an image processing unit that performs image processing such as detection of the maximum value as described above is provided, and the following processing is performed.

That is, in order to perform appropriate gain adjustment, the light source is turned on and the reflected light from the reference white plate is read by the line image sensor, and the gain adjustment of the analog signal output from each photoelectric conversion element at that time is performed. (Gain adjustment at the time of bright output) is performed in the same manner as the gain adjustment described above, and the light source is turned off so that the reflected light from the reference white plate is read by the line image sensor, and the light is output from each photoelectric conversion element at that time. The offset adjustment of the analog signal is performed in the same manner as the offset adjustment described above, and the analog signal on which the gain adjustment and the offset adjustment have been performed is A / A
After conversion into digital data (image data) by a D converter, an image having an appropriate density is obtained by performing black level correction and shading correction.

[0011]

In a conventional image reading apparatus, when performing gain adjustment and offset adjustment of an analog signal, image data such as averaging of collected data, detection of a maximum value, detection of a minimum value, and correction of subtraction of black data are used. Although an image processing unit for performing the processing is provided inside, the image forming apparatus connected to the image reading apparatus separately from the image processing unit also includes the image processing unit.

Therefore, when the image processing section of the image forming apparatus also performs image processing such as averaging of collected data, detection of the maximum value, detection of the minimum value, the processing becomes double, and the same processing is performed. Since it is necessary to control whether the operation is performed by the reading apparatus or the image forming apparatus, the cost is increased.

In some cases, the image forming apparatus needs to acquire uncorrected image data from the image reading apparatus. For example, when editing processing is performed on image data obtained from an image reading device using a computer or the like, if the image data is subjected to shading correction or the like, a problem occurs if the image data is a monotonous image such as a character or a line drawing. However, a faithful image cannot be reproduced with a photograph or an image expressing an intermediate color, which may hinder the editing process.

On the other hand, in a conventional image reading apparatus, reflected light from a reference white plate is read by a line image sensor,
At this time, the digital data output from the A / D converter is treated as white shading data and shading correction is performed to correct the sensitivity variation and the light amount variation of the photoelectric conversion element. is there.

For this reason, even if shading correction can be performed each time to obtain an appropriate image density, there is a problem that a difference occurs in the image density between the image reading apparatuses. Also, when the reference white plate is replaced, there is a problem that a difference occurs in image density between before and after the replacement.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in an image reading processing system, an image reading device and an external device such as an image forming device can commonly use one image processing section. It is an object of the present invention to reduce costs and increase flexibility of image data. In addition, it absorbs variations in the density of the reference white plate, eliminates the image density difference between the image reading devices and the image density difference before and after replacement of the reference white plate, so that a constant image density can be always obtained. The purpose is also.

[0017]

According to the present invention, there is provided a document conveying means for conveying a document, a reference white plate used for adjusting image density, and illumination of a document or a reference white plate conveyed by the document conveying means. Light source and a one-dimensional array in the main scanning direction orthogonal to the sub-scanning direction, which is the direction of document transport. When the light source is turned on or off, the light reflected from the document or the reference white plate is read and converted to an analog signal. A line image sensor having a plurality of photoelectric conversion elements that output in parallel in parallel, an offset adjustment unit that adjusts an offset of an analog signal output from each photoelectric conversion element of the line image sensor, Gain adjusting means for adjusting the gain of the analog signal output from each of the conversion elements; and offset adjusting means. The analog signal gain adjustment is performed by the offset adjustment and the gain adjustment means into digital data and outputs it as image data A /
An image reading apparatus including: a D conversion unit; an image conversion unit that converts the image data output from the unit into one main scanning line in a permutation and outputs the image data; and image data output from the image conversion unit of the image reading device. The above object is achieved in an image reading processing system including an external device such as an image forming apparatus having an image processing means for performing various image processing including detection of a maximum value on the image data. Therefore, it is characterized as follows.

According to the first aspect of the present invention, the image reading device turns off the light source, causes the line image sensor to read the reflected light from the reference white plate, and obtains the image data output from the image conversion means at that time. First image data acquisition instructing means for instructing the external device, and acquiring the maximum value of the image data output from the image converting means detected by the image processing means of the external device after the instruction is performed by the means. A first maximum value acquisition unit, a first offset amount adjustment unit that calculates an offset amount by the offset adjustment unit based on the maximum value acquired by the unit, and adjusts the offset amount; and an offset by the unit. After the adjustment of the amount, the light source is turned on, the reflected light from the reference white plate is read by the line image sensor, and the light output from the image conversion means at that time is output. Second image data acquisition instructing means for instructing the external device to acquire the image data, and image data output from the image converting means detected by the image processing means of the external device after the instruction is given by the means. Second maximum value obtaining means for obtaining a maximum value, and first gain amount adjusting means for calculating a gain amount by the gain adjusting means based on the maximum value obtained by the means and adjusting the gain amount Are provided.

According to a second aspect of the present invention, in the image reading processing system of the first aspect, when the image processing means of the external device is instructed to acquire the image data output from the image conversion means by the image reading apparatus, Image data obtaining means for obtaining image data, image area specifying means for specifying an image area corresponding to the gain adjusting means, and an image specified by the image area specifying means among image data obtained by the image data obtaining means Multiple addition and averaging processing means for reading the image data of the area for several sub-scan lines in pixel units and performing multiple addition and averaging of pixels; and image data subjected to multiple addition and averaging of pixels by the means. And a maximum value detecting means for detecting the maximum value from the maximum value.

According to a third aspect of the present invention, in the image reading processing system according to the first or second aspect, the light source is turned off to reflect the light from the reference white document or the reference white document conveyed by the document conveying means. Third image data acquisition instructing means for causing the line image sensor to read light and instructing the external device to acquire image data output from the image conversion means at that time; and A third maximum value acquisition unit that acquires the maximum value of the image data output from the image conversion unit detected by the image processing unit, and an offset amount by the offset adjustment unit based on the maximum value acquired by the unit. A second offset amount adjusting means for calculating and adjusting the offset amount; and turning on the light source after adjusting the offset amount by the means. And causing the line image sensor to read the reflected light from the reference white document conveyed by the document conveying means, and instructing the external device to obtain the image data output from the image converting means at that time. Instruction means, and fourth maximum value acquisition means for acquiring the maximum value of the image data output from the image conversion means detected by the image processing means of the external device after the instruction by the means is given; Calculating the gain amount by the gain adjusting means based on the maximum value obtained by
Second gain amount adjusting means for adjusting the gain amount;
After the gain amount is adjusted by the means, the light source is turned on, the reflected light from the reference white plate is read by the line image sensor, and the acquisition of the image data output from the image conversion means at that time is instructed to the external device. Fifth image data acquisition instructing means, and a fifth maximum value for acquiring the maximum value of image data output from the image converting means detected by the image processing means of the external device after the instruction by the means is performed An acquisition unit and a reference voltage adjustment unit that calculates a reference value of a reference white plate based on the maximum value acquired by the unit and adjusts a reference voltage input to an A / D converter are provided.

[0021]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a diagram showing an example of a configuration of a main part of a long and large digital copying machine (hereinafter, simply referred to as "digital copying machine") as an image reading processing system embodying the present invention.

In this digital copying machine, the image reading device 1 and the image forming device 2 are individually configured. The image reading device 1 includes a line image sensor 5, a read signal conversion unit 4, a read control unit 3, a document transport device 8 (document transport unit), and a reference white roller 7 (reference white plate). . The image forming apparatus 2 includes an image processing unit 6 and an image forming unit 21.

FIG. 3 is a diagram showing an example of the structure of the mechanism of the line image sensor 5 of FIG. The line image sensor 5 is provided with a plurality of photoelectric conversion elements 51 one-dimensionally arranged in a main scanning direction orthogonal to a sub-scanning direction, which is a direction in which the original is conveyed by the original conveying device 8. The array 52 is provided with light sources (fluorescent lamps) 5 on both sides thereof.
3, 53 are provided respectively. Further, below the selfoc lens array 52, a reference white roller 7 as a reference white plate is provided.

In the line image sensor 5, when acquiring white shading correction data, the light source 53 is turned on to illuminate the reference white roller 7, and the reflected light from the reference white roller 7 is transmitted to the selfoc lens array 52. Read (read) by each photoelectric conversion element 51 via
Convert to analog signal and output.

When reading the image of the original, the original inserted from the original insertion slot is conveyed by the original conveying device 8 shown in FIG. 2 so that the original passes between the reference white roller 7 and the SELFOC lens array 52 and , Light source 53
Is turned on to illuminate the image surface of the original, and the reflected light (image) from the image surface is read by each photoelectric conversion element 51 via the SELFOC lens array 52, converted into an analog signal, and output.

FIG. 1 is a block diagram showing an example of the configuration of the control unit of the digital copying machine shown in FIG. Image reading device 1
, Each photoelectric conversion element 5 of the line image sensor 5
Reference numeral 1 designates eight outputs, divides one main scanning line into eight, and outputs the divided signals to the reading signal conversion unit 4 in parallel as analog signals.

The reading control section 3 controls the line image sensor 5 and the reading signal converting section 4.
The first to fifth image data acquisition instructing means according to claim 1,
It functions as first to fifth maximum value acquiring means, first and second offset amount adjusting means, first and second gain amount adjusting means, and reference voltage adjusting means.

The read signal converter 4 includes eight gain amplifiers (AMPs) corresponding to the output of the line image sensor 5.
41, an offset adjuster (OFS) 42, four A / D converters (ADC) 43, and one image converter 44. Each gain amplifier 41 is
It corresponds to the gain adjusting means of claims 1 to 3,
The analog signal from the corresponding output unit of the line image sensor 5 is amplified (gain adjusted) and output to the corresponding offset adjuster 42.

Each of the offset adjusters 42 corresponds to the offset adjusting means of claims 1 to 3,
It adjusts the offset (offset component) of the analog signal from the corresponding gain amplifier 41 and outputs it to the corresponding A / D converter 43. At this time, two analog signals respectively output from the offset adjusters 42 are collected and input to each A / D converter 43.

Each of the A / D converters 43 corresponds to an A / D converter in claims 1 to 3, and converts analog signals from the corresponding two offset adjusters 42 into digital data. Output as image data.
Here, in each A / D converter 43, when converting an analog signal into digital data, a reference voltage (corresponding to the reference value of claim 3) for the analog signal is required.

When the line image sensor 5 reads the image of the document, a fixed voltage is input as the reference voltage, and when the reference white roller 7 used for the white shading data is read, a reference white document described later is read. The set voltage obtained in the used reference whiteboard adjustment process is input.

The image converter 44 corresponds to the image conversion means of claims 1 to 3, and each A / D converter 43
Output image data (digital data) one by one (a total of four) in parallel from each other. In order to send these to the image processing unit 6 of the image forming apparatus 2 in a permutation in one main scanning line, The image data (pixel data) from the A / D converter 43 is rearranged (the image data is converted into one main scan line in a permutation), and the rearranged image data is processed by the image forming apparatus 2. Send it to the unit 6.

The image processing unit 6 of the image forming apparatus 2 corresponds to the image processing means (image data acquisition means, image area designating means, multiple addition averaging processing means, maximum value detecting means) according to claims 1 to 3. The averaging process, the maximum value detection, the minimum value detection, the white shading correction, and the
Various image processing including black shading correction, MTF correction, edge detection, and gamma correction is performed. Also, for the parallel output divided into 8 parts of the line image sensor 5,
As shown in the following (1) to (8), re-division is performed to obtain image data.

(1) Image data of the area of the first block (block 1) in the area of each divided block of the line image sensor 5 (corresponding to each gain amplifier 41 and each offset adjuster 42) In order to acquire (a signal obtained by converting an analog signal output from the photoelectric conversion element 51 in that area into digital data), as shown in FIG.
ODD [0: 7] and EVEN [0: in synchronization with the YNC signal
The pixel of [7] is measured, the area of the first block is designated by the XLGATE signal, and image data of the area is acquired. The digital copying machine of this embodiment has a reading width A0, and the line image sensor 5 also includes a photoelectric conversion element 51 of 15360 pixels corresponding to the A0 width.

In the line image sensor 5, since the area from the first pixel to the 384th pixel is an invalid area, the XLGATE signal is controlled so as to become valid from the 385th pixel so as not to acquire image data in this area. . Since the output is divided into eight by the line image sensor 5, 1
XLG in 1920 pixel units, which is 8 divisions of 5360 pixels
Control the ATE signal. Therefore, in the case of the first block, the area from 385 pixels to 1920 pixels is regarded as an effective area, and the XLGATE signal is made effective (low level “L”) during that time.

(2) In order to acquire image data of the area of the second block (block 2) of the line image sensor 5, as shown in FIG. 5, it is synchronized with the XOPWSYNC signal sent from the image reading device 1. ODD [0: 7], E
The pixel of VEN [0: 7] is measured and 3 from the 1921 pixel.
The XLGATE signal is enabled up to the 840th pixel, and image data of the area is acquired.

(3) In order to obtain image data of the area of the third block (block 3) of the line image sensor 5, the image data is synchronized with the XOPWSYNC signal sent from the image reading apparatus 1 as shown in FIG. ODD [0: 7], E
The pixel of VEN [0: 7] is measured and 5 is calculated from the 3841th pixel.
The XLGATE signal is enabled up to the 760th pixel, and image data of the area is acquired.

(4) In order to acquire image data of the area of the fourth block (block 4) of the line image sensor 5, as shown in FIG. 7, the image data is synchronized with the XOPWSYNC signal sent from the image reading apparatus 1. ODD [0: 7], E
The pixel of VEN [0: 7] is measured and it is 7 from the 5761th pixel.
The XLGATE signal is enabled up to the 860th pixel, and image data of the area is acquired.

(5) In order to acquire the image data of the area of the fifth block (block 5) of the line image sensor 5, the image data is synchronized with the XOPWSYNC signal sent from the image reading apparatus 1 as shown in FIG. ODD [0: 7], E
The pixel of VEN [0: 7] is measured and measured from pixel 7681 to 9
The XLGATE signal is enabled up to the 600th pixel, and image data of the area is acquired.

(6) In order to obtain image data in the area of the sixth block (block 6) of the line image sensor 5, the image data is synchronized with the XOPWSYNC signal sent from the image reading device 1 as shown in FIG. ODD [0: 7], E
The pixel of VEN [0: 7] is measured, and 1 is counted from the 9601th pixel.
The XLGATE signal is enabled up to the 1520th pixel, and image data of the area is acquired.

(7) To acquire image data of the area of the seventh block (block 7) of the line image sensor 5, as shown in FIG. 10, in synchronization with the XOPWSYNC signal sent from the image reading device 1. ODD [0: 7],
The pixels of EVEN [0: 7] are measured, and the XLGATE signal is made valid from the 11521th pixel to the 13440th pixel,
The image data of the area is obtained.

(8) In order to acquire image data of the area of the eighth block (block 8) of the line image sensor 5, as shown in FIG. 11, the image data is synchronized with the XOPWSYNC signal sent from the image reading device 1. ODD [0: 7],
The pixel of EVEN [0: 7] is measured, and the XLGATE signal is made valid from the 13441th pixel.

In this line image sensor 5, 1497
Since the 7th pixel to the 15360th pixel are invalid areas, X is set so that image data in this area is not acquired.
The LGATE signal is controlled to become invalid from the 14977th pixel, the 13441th pixel to the 14977th pixel are regarded as a valid area, and image data in that area is acquired.

As described above, the image processing section 6 captures image data, performs various image processing including averaging processing and maximum value detection on the image data, and outputs image data subjected to the various image processing. . The image forming unit 21 performs an image forming process based on the image data from the image processing unit 6 to form an image on a sheet.

Next, processing relating to the present invention in the digital copying machine will be specifically described with reference to FIGS. FIG. 12 is a flowchart illustrating an example of a main routine of the image density adjustment processing (automatic adjustment sequence when the power is turned on) by the reading control unit 3 of the image reading apparatus 1.

FIG. 13 is a flowchart showing an example of a subroutine of offset adjustment processing by reading the dark output level by the reading control section 3 of the image reading apparatus 1. FIG. 14 is a flowchart illustrating an example of a subroutine of a gain adjustment process by reading the bright output level by the reading control unit 3 of the image reading device 1. FIG.
9 is a flowchart illustrating an example of a routine of image data acquisition processing related to image density adjustment processing by an image processing unit of the image forming apparatus.

In this digital copying machine, when the power of the image reading apparatus 1 is turned on, the power of the image forming apparatus 2 is also turned on in conjunction with the power, and each of the apparatuses starts operating. Then, in the image reading apparatus 1, the reading control unit 3
As shown in (1), first, in step S1, the read signal converter 4 is initialized. That is, predetermined initial values (gain amounts and offset amounts) are set in each of the gain amplifiers 41 and each of the offset adjusters 42, and each A / D converter 43 has a maximum value used as a reference voltage when reading an original image. Input a fixed voltage and let it be set.

Next, in step S2, the dark output level is read, and the offset amount of each offset adjuster 42 is adjusted (offset adjustment). That is, since the dark output level is obtained by reading the reflected light from the reference white roller 7 with the light source (fluorescent lamp) 53 turned off, first, as shown in FIG. Is turned off, and the image forming apparatus 2 is turned off in step S12.
Is instructed to start acquiring image data (image data of each block area of the line image sensor 5) output from the image converter 44.

When the image processing unit 6 of the image forming apparatus 2 is instructed to start acquiring image data of each block area of the line image sensor 5, the image processing unit 6 acquires image data of each block area. As shown, first, in step S3
1, the area (image area) of the first block (corresponding block) is designated, and in step S32, the image data of the area is read by several sub-scanning lines in pixel units, and the pixel multiple addition averaging process ( (Pixel averaging process).

Next, in step S33, the maximum value (or the minimum value and the maximum value may be detected) is held from the image data (pixels for which the area is specified) on which the pixel multiple addition averaging process has been performed. In S34, it is determined whether or not the processing in steps S31 to S33 has been performed on the area of all the blocks of the line image sensor 5, but since the processing has only been performed on the area of the first block, the flow returns to step S31. Then, the area of the next block (the second block) is designated, and thereafter the same processing as described above is sequentially performed on the area of all the blocks of the line image sensor 5.

The reading control section 3 of the image reading apparatus 1 performs the processing of step S12 in FIG. 13 (instructs the image processing section 6 of the image forming apparatus 2 to start acquiring the image data of the area of each block of the line image sensor 5). As a result, the maximum value of the image data of each block area of the line image sensor 5 is detected by the image processing unit 6 as described above. Obtained from the processing unit 6.

Next, in step S14, each offset adjuster 42 corresponding to each block of the line image sensor 5 based on the maximum value (or maximum value and minimum value) of the image data of each block area of the line image sensor 5 acquired. A set value (offset amount) is calculated such that a value to be set next time (target value) is read, and each set value is set in the offset adjuster 42 to adjust each set value (each set value). Block offset adjustment).

This process is repeated until the read value (the output value of each offset adjuster 42) matches the target value (the target read value). When this processing is performed, the value (read value) read after setting the offset amount fluctuates around the target value as shown in FIG. 16, for example, so that the set value (offset amount) also fluctuates accordingly. Finally, feedback control is performed so that the read value converges to the target value.

After the adjustment (offset adjustment) of each offset adjuster 42 is completed, the reading control section 3 of the image reading apparatus 1 reads the bright output level in step S3 of FIG. Perform adjustment (gain adjustment).

That is, the bright output level depends on the light source (fluorescent lamp).
It is obtained by reading the reflected light from the reference white roller 7 in a state where 53 is turned on (actually, a reference voltage set by a preset reference white plate reference value is input to the A / D converter 43, As shown in FIG. 14, a light source (fluorescent lamp) 53 is first turned on in step S21, and the image processing unit 6 of the image forming apparatus 2 is turned on in step S22, as shown in FIG. An instruction to start acquiring image data (image data of each block area of the line image sensor 5) output from the image converter 44 is issued.

When the image processing unit 6 of the image forming apparatus 2 is instructed to start acquiring the image data of the area of each block of the line image sensor 5, the image processing unit 6 acquires the image data of the area of each block and performs the offset adjustment. 15 (FIG. 15)
Refer to). Reading control unit 3 of image reading device 1
Performs the processing of step S22 in FIG. 14 (instructs the image processing unit 6 of the image forming apparatus 2 to start acquiring the image data of the area of each block of the line image sensor 5). Since the maximum value of the image data in the area of each block of No. 5 is detected,
In step S23, the maximum value of the image data of the area of each block is acquired from the image processing unit 6.

Next, in step S24, based on the maximum value (or maximum and minimum values) of the image data of the area of each block of the line image sensor 5 acquired, the respective gain amplifiers 41 corresponding to each block are sent to the respective gain amplifiers 41. A set value (gain amount) is calculated so that a value (target value) to be set next time is read, and each gain amplifier 4
It is set to 1 to adjust each set value (gain adjustment of each block).

This process is repeated until the read value (output value of each gain amplifier 41) matches the target value (target read value). This process is also a feedback control as shown in FIG. 16 as in the case of adjusting the offset amount. When this process ends, the light source (fluorescent lamp) 53 is turned off in step S25. When the adjustment of the offset amount and the adjustment of the gain amount are completed, appropriate image data can be obtained as image data of the document, so that the image of the document can be read.

When each A / D converter 43 converts an analog signal from each offset adjuster 42 into digital data, a reference voltage for the analog signal is required. When reading the image of the original,
Since the read image can be expressed more precisely when the resolution is used to the maximum, the reference voltage is set to the maximum value, and each A / A
Each is input to the D converter 43.

When reading the reflected light of the reference white roller 7 used for the white shading data, a voltage set by the reference white plate reference value is input to each A / D converter 43. This is a reference white roller 7 which is a reference white plate.
This is for suppressing the variation in the density of the light.

If the voltage set at the reference value of the reference white plate is not used and the same fixed voltage as that used when reading the image of the original is used, for example, as shown in FIG. The density of the image read from the document with the gain adjusted based on the reference white roller (reference white plate) A having the density and the image read from the document with the gain adjusted based on the other reference white roller B is determined after the shading correction. A difference occurs. This state occurs as a variation in the image density between the image reading apparatuses and a variation in the image density before and after the replacement of the reference white roller 7, and it is impossible to obtain a constant image density.

Therefore, in the digital copying machine of this embodiment, in order to avoid the above-described state, a reference white plate using a reference white original is used immediately after the device is manufactured, when the reference white roller 7 is replaced, and when the line image sensor 5 is replaced. Perform adjustment processing. Hereinafter, the processing will be described.

FIG. 17 is a flowchart showing an example of a main routine of a reference whiteboard adjustment process using a reference white original by the reading control section 3 of the image reading apparatus 1. FIG.
8 is a flowchart illustrating an example of a subroutine of a reference point setting process of a reference white plate by reading a bright output level by the reading control unit 3 of the image reading apparatus 1.

After performing the above-described image density adjustment processing (automatic adjustment sequence when the power is turned on), the reading control section 3 of the image reading apparatus 1 executes the processing in FIG. And first, step S
At 41, the read signal conversion unit 4 is initialized, and step S4
2, the dark output level is read, and each offset adjuster 42
Is performed (offset adjustment). These processes are the same as the image density adjustment process (automatic adjustment sequence at power-on) in FIG.

Next, when a reference white document (not shown) is inserted (set) into the document insertion slot, this is detected in step S43, and the document feeder 8 is driven to move the reference white document to the position of the line image sensor 5. Move (convey) to Then, in step S44, the bright output level is read, and the gain amount of each gain amplifier 41 is adjusted (gain adjustment). This process is substantially the same as the image density adjustment process of FIG. 12, but the reference voltage input to the A / D converter 43 is the same maximum fixed voltage as when reading an image on a document (see FIG. 20).

When the adjustment of the gain of each gain amplifier 41 is completed, the document feeder 8 is driven in step S45 to discharge the reference white document. Thereafter, the bright output level is read based on each offset adjuster 42 and each gain amplifier 41 adjusted (set) using the reference white original in step S46, and the reference point of the reference white roller 7 is set.

That is, the bright output level depends on the light source (fluorescent lamp).
It is obtained by reading the reflected light from the reference white roller 7 with the light 53 turned on (actually, the reference voltage input to the A / D converter 43 is changed to the voltage set by the reference white plate reference value, and As shown in FIG. 18, a light source (fluorescent lamp) 53 is first turned on in step S51, and an image is sent to the image processing unit 6 of the image forming apparatus 2 in step S52, as shown in FIG. An instruction to start acquiring image data (image data of each block area of the line image sensor 5) output from the converter 44 is issued.

When the image processing unit 6 of the image forming apparatus 2 is instructed to start acquiring the image data of the area of each block of the line image sensor 5, the image processing unit 6 acquires the image data of the area of each block and performs the offset adjustment. 15 (FIG. 15)
Refer to). Reading control unit 3 of image reading device 1
Performs the processing of step S52 in FIG. 18 (instructs the image processing unit 6 of the image forming apparatus 2 to start acquiring the image data of the area of each block of the line image sensor 5). Since the maximum value of the image data in the area of each block of No. 5 is detected,
In step S53, the maximum value of the image data of the area of each block is acquired from the image processing unit 6.

Next, in step S54, the largest of the maximum values of the image data of the fourth block (block 4) or the fifth block (block 5), which is the designated block of the line image sensor 5, is obtained. By using the values, for example, as shown in FIG.
The reference white plate reference value (reference point) is calculated and set so that the maximum value obtained from the above becomes equal to the maximum value obtained by the gain adjustment, and the reference voltage is adjusted and set.

The reason why the fourth block or the fifth block of the line image sensor 5 is used is that the position where the document is placed is set from the center of the line image sensor 5. After the reference white plate reference value (reference point) is set, the light source (fluorescent lamp) is set in step S55.
53 is turned off, and the process ends. The set reference white plate reference value is reflected from the next image density adjustment processing (automatic adjustment sequence at power-on).

By performing this process, as shown in FIG. 21, for example, even if the reference white rollers A and B having different densities are used as the reference white roller 7, the variation can be converged by the reference white reference value. it can. Before performing the processing in step S42, the same processing as in step S43 may be performed. Thereby, step S4
In No. 2, when reading the dark output level, the reflected light from the reference white document is read.

As described above, in the digital copying machine (image reading processing system) of the present embodiment, the reading control unit 3 of the image reading apparatus 1 turns off the light source 53 and sends the reflected light from the reference white roller 7 to the line. Instruct the image forming apparatus 2 to obtain image data of each block area of the line image sensor 5 output from the image converter 44 at that time, and instruct the image forming apparatus 2 to read the image data. 6, the maximum value of the image data of the area of each block detected by each block is acquired, the offset amount by each offset adjuster 42 is calculated based on each maximum value, and the offset amount is adjusted. Is turned on, the reflected light from the reference white roller 7 is read by the line image sensor 5, and the line output from the image converter 44 at that time is read. The image sensor 5 instructs the image forming apparatus 2 to acquire the image data of the area of each block of the image sensor 5, and acquires the maximum value of the image data of the area of each block detected by the image processing unit 6 of the image forming apparatus 2. Since the gain amount by each gain amplifier 41 is calculated based on the maximum value and the gain amount is adjusted, that is, one image processing unit 6 can be commonly used by the image reading apparatus 1 and the image forming apparatus 2. , Cost can be reduced.

Further, since the gain amplifier 41 and the offset adjuster 42 are provided for each block area of the line image sensor 5, the central portion generated by the light source 53 such as a fluorescent lamp used in the long line image sensor 5 is used. By adjusting the gain amounts of the individual gain amplifiers 41 and the offset amounts of the individual offset adjusters 42, it is possible to absorb (eliminate) the difference between the light amounts at the two ends and before and after shading correction.

Further, since the image reading device 1 supplies the image data which is not subjected to the image processing to the image forming device 2, the image processing section 6 of the image forming device 2 can edit the faithful image data, Greater flexibility.

On the other hand, when the image processing unit 6 of the image forming apparatus 2 instructs the image reading device 1 to acquire the image data of the area of each block output from the image converter 44, the image processing unit 6 of the Image data is acquired, an image area corresponding to each gain amplifier 41 is designated, and among the acquired image data of each block area, several sub-scan lines for each pixel of the image data of the designated area are obtained. Read and perform pixel multiple averaging processing,
Since the maximum value is detected from each image data on which the multiple addition averaging process has been performed, the maximum value of the image data in the area of each block can be efficiently detected with high accuracy.

Therefore, since the gain amount of the gain amplifier 41 and the offset amount of the offset adjuster 42 of the image reading device 1 are always stable, a stable image density can be always obtained. Further, abnormality monitoring can be performed by monitoring the stable gain amount of the gain amplifier 41 and the offset amount of the offset adjuster 42.

Further, in the image reading apparatus 1, the light source 53 is turned off so that the line image sensor 5 reads the reflected light from the reference white roller 7 (which may be a reference white original conveyed by the original conveying device 8). It instructs the image forming apparatus 2 to acquire the image data of the area of each block of the line image sensor 5 output from the image converter 44 at that time, and each block detected by the image processing unit 6 of the image forming apparatus 2. The maximum value of the image data of the area is obtained, the offset amount is calculated by the offset adjuster 42 based on the maximum value, and the offset amount is adjusted. The line image sensor 5 reads the reflected light from the reference white document conveyed by the
To the image forming apparatus 2 to obtain the image data of the area of each block of the line image sensor 5 output from the
The maximum value of the image data of the area of each block detected by the image processing unit 6 of the image forming apparatus 2 is obtained, the gain amount of each gain amplifier 41 is calculated based on each maximum value, and the gain amount is calculated. After making adjustments, the light source 53
Is turned on so that the reflected light from the reference white roller 7 is read by the line image sensor 5, and the image data of each block area of the line image sensor 5 output from the image converter 44 at that time is acquired by the image forming apparatus. 2, the maximum value of the image data of the area of each block detected by the image processing unit 6 of the image forming apparatus 2 is obtained,
The reference value of the reference white roller 7 is calculated based on each of the maximum values, and the reference voltage input to each A / D converter 43 is adjusted. The image density difference between the apparatuses and the image density difference before and after the replacement of the reference white roller 7 are eliminated,
A constant image density can always be obtained. In addition, since the variation in the density of the reference white roller 7 can be absorbed, the density accuracy of the reference white roller 7 is reduced, and the effect of reducing the manufacturing cost can be obtained.

Although the embodiment in which the present invention is applied to a digital copying machine including an image reading apparatus and an image forming apparatus has been described above, the present invention is not limited to this, and includes an image reading apparatus and an image forming apparatus. The present invention can be applied to an image reading processing system including an image reading apparatus and an external device other than the image forming apparatus, as well as a digital multifunction peripheral and a facsimile apparatus.

[0079]

As described above, according to the image reading processing system of the present invention, one image processing means can be commonly used by the image reading device and the external device, so that the cost can be reduced. In addition, since the image reading device supplies the image data that is not subjected to the image processing to the external device, the image processing means of the external device can edit the faithful image data, thereby increasing the flexibility of the image data.

Further, according to the invention of claim 2, since the image processing means of the external device can efficiently and efficiently detect the maximum value of the image data from the image reading device,
The gain amount of the gain adjustment unit and the offset amount of the offset adjustment unit of the image reading device are always stable, and accordingly, a stable image density can be always obtained.

According to the third aspect of the invention, since the variation in the density of the reference white plate can be absorbed, the image density difference between the image reading devices and the image density difference before and after the replacement of the reference white plate are eliminated. A constant image density can always be obtained. Further, since the variation in the density of the reference white plate can be absorbed, the accuracy of the density of the reference white plate can be reduced, and the effect of reducing the manufacturing cost can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a control unit of the digital copying machine illustrated in FIG. 2;

FIG. 2 is a diagram illustrating a configuration example of a main part of a long and large digital copying machine as an image reading processing system embodying the present invention;

FIG. 3 is a diagram illustrating a configuration example of a mechanism of the line image sensor 5 of FIG. 2;

FIG. 4 is a timing chart for explaining a process of acquiring image data of a block 1 area of the line image sensor 5 output from the image reading device 1 by the image processing unit 6 of FIG. 1;

FIG. 5 is a timing chart for explaining a process of acquiring image data in the area of block 2;

FIG. 6 is a timing chart for explaining a process of acquiring image data in the area of block 3;

FIG. 7 is a timing chart for explaining a process of acquiring image data of an area of the same block 4;

FIG. 8 is a timing chart for explaining a process of acquiring image data in the area of the block 5;

FIG. 9 is a timing chart for explaining a process of acquiring image data in the area of the block 6;

FIG. 10 is a timing chart for explaining a process of acquiring image data in an area of a block 7;

FIG. 11 is a timing chart for explaining a process of acquiring image data in the area of the block 8;

FIG. 12 is a flowchart showing an example of a main routine of an image density adjustment process (automatic adjustment sequence at power-on) by a reading control unit 3 of the image reading apparatus 1 shown in FIG.

FIG. 13 is a flowchart showing an example of a subroutine of offset adjustment processing by reading a dark output level.

FIG. 14 is a flowchart showing an example of a subroutine of gain adjustment processing by reading a bright output level.

15 is an image processing unit 6 of the image forming apparatus 2 shown in FIG.
FIG. 7 is a flowchart showing an example of a routine of image data acquisition processing relating to image density adjustment processing by the image processing apparatus.

16 shows an example of the relationship between values (offset amount, gain amount) set during adjustment of the offset amount and gain amount of each offset adjuster 42 and each gain amplifier 41 in FIG. 1 and values read after the setting. FIG.

FIG. 17 is a flowchart illustrating an example of a main routine of a reference whiteboard adjustment process using a reference white original by the reading control unit 3 of the image reading apparatus 1 illustrated in FIG. 1;

FIG. 18 is a flowchart showing an example of a subroutine of reference point setting processing of a reference white plate by reading a bright output level.

FIG. 19 is an explanatory diagram serving to explain a reference white plate adjustment process using the reference white document shown in FIGS. 17 and 18;

FIG. 20 is another explanatory diagram for explaining the reference white plate adjustment process using the reference white document.

FIG. 21 is still another explanatory diagram for describing a reference white plate adjustment process using a reference white document.

[Explanation of symbols]

 1: image reading device 2: image forming device 3: reading control portion 4: reading signal conversion portion 5: line image sensor 6: image processing portion 7: reference white roller 8: document conveying device 21: image forming portion 41: gain Amplifier 42: Offset adjuster 43: A / D converter 44: Image converter 51: Photoelectric conversion element 52: Selfoc lens array 53: Light source (fluorescent lamp)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) RR12

Claims (3)

[Claims] 1. A document conveying means for conveying a document, a reference white plate used for adjusting image density, a light source for illuminating the document conveyed by the document conveying means or the reference white plate, and Are arranged one-dimensionally in the main scanning direction orthogonal to the sub-scanning direction, which is the transport direction of the light source. When the light source is turned on or off, the light reflected from the original or the reference white plate is read and converted into an analog signal. A line image sensor having a plurality of photoelectric conversion elements that output in parallel; offset adjustment means for adjusting an offset of an analog signal output from each photoelectric conversion element of the line image sensor; Gain adjustment means for adjusting the gain of the analog signal output from each of the conversion elements; A / D conversion means for converting an analog signal subjected to offset adjustment by the stage and gain adjustment by the gain adjustment means into digital data and outputting the same as image data, and converting the image data output from the means into one main scanning line An image reading device having an image converting means for converting the image data into a permutation and outputting the image data; and obtaining image data output from the image converting means of the image reading device, and detecting a maximum value of the image data. In an image reading processing system comprising an external device such as an image forming apparatus having an image processing means for performing various image processing including, in the image reading device, the light source is turned off and reflected light from the reference white plate is reflected. Instruct the external device to read the line image sensor and obtain image data output from the image conversion unit at that time. First image data acquisition instructing means for acquiring the maximum value of the image data output from the image converting means detected by the image processing means of the external device after the instruction by the means is performed; Value obtaining means, first offset amount adjusting means for calculating an offset amount by the offset adjusting means based on the maximum value obtained by the means, and adjusting the offset amount, and offset amount by the means After the adjustment, the light source is turned on and the reflected light from the reference white plate is read by the line image sensor,
Second image data acquisition instructing means for instructing the external device to acquire image data output from the image converting means at that time, and detecting by the image processing means of the external device after the instruction is given by the means. A second maximum value obtaining unit that obtains the maximum value of the image data output from the image conversion unit, and a gain amount calculated by the gain adjustment unit based on the maximum value obtained by the unit.
An image reading processing system comprising: a first gain amount adjusting means for adjusting the gain amount. 2. The image reading processing system according to claim 1, wherein the image processing unit of the external device is configured to execute the image processing when the image reading device instructs acquisition of image data output from the image converting unit. Image data acquiring means for acquiring data, image area designating means for designating an image area corresponding to the gain adjusting means, and image data designated by the image area designating means among image data acquired by the image data acquiring means. Averaging processing means for reading the image data of the image area by several sub-scanning lines in pixel units and performing multiplex averaging processing of pixels, and the multiplex averaging processing of pixels is performed by the means. An image reading processing system comprising: a maximum value detecting unit that detects a maximum value from image data. 3. The image reading processing system according to claim 1, wherein the light source is turned off by the image reading device, and the light is reflected from the reference white plate or a reference white document conveyed by the document conveying means. Third image data acquisition instructing means for causing the line image sensor to read light, and instructing the external device to acquire image data output from the image converting means at that time, and after the instruction by the means is performed, A third maximum value acquisition unit that acquires a maximum value of image data output from the image conversion unit detected by the image processing unit of the external device, and the offset based on the maximum value acquired by the unit. Second offset amount adjusting means for calculating an offset amount by the adjusting means and adjusting the offset amount; After the adjustment, the light source is turned on, the reflected light from the reference white document conveyed by the document conveying means is read by the line image sensor, and the acquisition of the image data output from the image converting means at that time is performed. Fourth image data acquisition instructing means for instructing the external device, and a maximum value of image data output from the image converting means detected by the image processing means of the external device after the instruction is performed by the means; Fourth maximum value acquisition means for acquiring the maximum value, a second gain amount adjustment means for calculating a gain amount by the gain adjustment means based on the maximum value acquired by the means, and adjusting the gain amount; After the gain amount is adjusted by the means, the light source is turned on and the reflected light from the reference white plate is read by the line image sensor. Fifth image data acquisition instructing means for instructing the external device to acquire image data output from the image conversion means, and the image data is detected by the image processing means of the external device after the instruction by the means is performed. A fifth maximum value acquisition unit that acquires a maximum value of the image data output from the image conversion unit; and a reference value of the reference white plate based on the maximum value acquired by the unit; An image reading processing system comprising: a reference voltage adjusting unit that adjusts a reference voltage input to a D converter.