JP2002262092A - Device and system for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device for stably adjusting gradation and gray balance concerning various kinds of sheets of paper being different in color or transfer characteristic. SOLUTION: An image forming system is provided with a scanner 100 for optically scanning an original and converting it into an image signal, an image processing part 200 for performing an image processing in the image signal read by the scanner 100, a printer part 300 for forming the image based on the image signal which is processed by the image processing part 200, a pattern generating part 208 for generating a test pattern signal to obtain the gradation characteristic of the printer part 300, a ROM for storing the multiple gradation characteristics to be targeted by the printer part 300 and an IPU control part 220 for selecting the target gradation characteristic among the multiple ones and correcting image forming gradation characteristic through the use of the reading value of the test pattern which is outputted by the printer part 300 and read by the scanner 100 and the selected target gradation characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital full-color copying machine having a function of adjusting image quality, and an image forming system including a processing apparatus for managing the functions.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as an electrophotographic copying machine has a problem that output characteristics change due to environmental fluctuations and fluctuations over time.

As a method of adjusting the output gradation characteristic,
The following methods are known. That is, after forming a certain degree of tone test pattern on the recording paper by the image forming means, the density of the tone test pattern on the formed recording paper is read by the image reading means, and correction conditions are set based on the image information. Is calculated and set in the γ correction means or the like. With this gradation correction function, the gradation and the stability of gray balance of the image forming apparatus can be maintained.

[0004]

However, in the conventional output tone adjustment method described above, the target tone characteristics are usually adjusted according to the dedicated paper for full-color printing. If test patterns are printed and adjusted on paper with different colors and transfer characteristics of recording paper such as overseas paper, the desired gradation characteristics cannot be obtained.
There is a problem that the image quality is affected as the gray balance is lost.

[0005] Further, if the density is insufficient or the density unevenness becomes large due to the variation over time, the range over which correction can be made by gradation correction is exceeded. In this case, even if the above-described test pattern is determined to be abnormal by reading the test pattern and the user is notified of the abnormality, the image must be used in an abnormal state until a serviceman is called for maintenance. There is a problem that it cannot be used.

The present invention has been made in view of the above circumstances, and provides an image forming apparatus capable of performing stable gradation and grace balance adjustments on various types of paper having different colors and transfer characteristics. The purpose is to do.

[0007] Further, the management side grasps the deterioration of the state of the image forming apparatus at an early stage, so that the image forming system can cope before the correction exceeds the correctable range and the administrator can cope with when an abnormality is detected. It is an object of the present invention to provide an image forming system that can be performed on the side.

[0008]

According to a first aspect of the present invention, there is provided an image reading means for optically scanning an original and converting the image into an image signal, and an image signal read by the reading means. Image processing means for performing image processing on
Image forming means for forming an image based on the image signal processed by the image processing means, test pattern generating means for generating a test pattern signal for acquiring the gradation characteristics of the image forming means, and image forming means. Storage means for storing a plurality of target gradation characteristics, selection means for selecting a target gradation characteristic from the plurality of target gradation characteristics, and a test pattern output by the image forming means and read by the image reading means And a gradation correction unit for correcting the gradation characteristics of image formation from the read values of the image data and the target gradation characteristics selected by the selection unit.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a determining means for determining the type of the recording paper, and the selecting means selects a target gradation characteristic based on the determination result of the paper determining means. It is characterized by the following.

According to a third aspect of the present invention, in the second aspect of the present invention, the paper determining means determines the type of the recording paper from a read value of a margin portion of the test pattern.

According to a fourth aspect of the present invention, there is provided an image reading means for optically scanning a document and converting it into an image signal, an image processing means for performing image processing on the image signal read by the reading means, and an image processing means. An image forming means for forming an image based on the processed image signal; a test pattern generating means for generating a test pattern signal for obtaining a gradation characteristic of the image forming means; and a target floor of the image forming means. Storage means for storing tone characteristics, a read value of the test pattern output by the image forming means, read by the image reading means, and a target value of the tone characteristics stored in the storage means, and the gradation of the image forming means is obtained. A tone correcting unit for correcting the characteristic, and a communication unit for transmitting a read value of the test pattern read by the reading unit when the tone correcting unit executes the tone correction. And having an image forming apparatus having, a, a processor for managing the reading of the test pattern transmitted by the communication unit of the image forming apparatus.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the image forming apparatus has a detecting means for detecting deterioration of the image forming means from a read value of the test pattern. When the deterioration of the state of the image forming means is detected by the detection means, the read value of the test pattern is transmitted to the processing means.

The invention according to claim 6 is the invention according to claim 4 or 5.
In the invention described in the description, the image forming apparatus has a second detecting unit that detects an abnormality of the image forming unit from a read value of the test pattern, and when the second detecting unit determines that the abnormality is abnormal, the test pattern is detected. The reading value is transmitted to the processing device, and the processing device creates gradation correction data based on the transmitted reading value and transmits the data to the corresponding image forming apparatus. It is characterized in that data is set in the gradation correction means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an image forming apparatus and an image forming system according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 9 show an embodiment of an image forming apparatus and an image forming system according to the present invention.

First, an embodiment of the image forming apparatus of the present invention will be described in detail with reference to FIG. FIG. 1 shows an embodiment in which the image forming apparatus of the present invention is applied to a one-drum digital full-color copying machine.

As shown in FIG. 1, in this embodiment, a scanner 100, an image processing unit 200, a printer unit 300, a system control unit 400, an operation unit 500, a display unit 600, and A
DF700.

The scanner 100 scans a document, converts it into a digital image signal, and outputs RGB data.

The image processing unit 200 performs a process such as a filter and color correction on the RGB data input from the scanner 100 and outputs any one of CMYK signals to the printer unit 300. In the case of the one-drum system, any one of the CMYK components is sent to the printer unit 300. Therefore, in the case of monochrome, the image processing is performed only once for K, and in the case of color, the image processing is performed four times in total.

The printer section 300 forms an image in accordance with output data from the image processing section 200. One printout is completed by a total of four image formations of K only in the case of monochrome and CMYK in the case of color.

An operation unit 500 is an input device for an operator to select a copy mode, set the number of copies, and the like, and includes various keys and a touch panel on a display unit.

The display unit 600 is a display device for displaying a setting state, giving a setting instruction to a user, and the like.

The ADF 700 is disposed above the scanner, and sequentially transports documents on a document table to the scanner.

The system control section 400 is composed of a microcomputer or the like, and outputs a signal for controlling the operation of the entire apparatus according to a program stored in advance in a ROM or the like.

Next, referring to FIG.
The configuration of the embodiment will be described. As shown in FIG. 2, the image processing unit 200 includes a density conversion unit 201 and a filter unit 20.
2. Color correction unit 203, selector 204, gradation correction unit 20
5, a gradation processing unit 206, an image memory 207, a pattern generation unit 208, an IPU control unit 220, and the like.

The scanner 100 outputs R, G, and B digital signals obtained by reading a document.

The density conversion unit 201 outputs R,
The G and B reflected light data are converted into density data using a look-up table.

The filter unit 202 performs an operation from the pixel of interest and its surrounding pixels, and performs image correction such as smoothing and edge enhancement.

The color correction unit 203 performs color correction (masking) to remove the turbid component of the color separation filter of the scanner and the turbid component of the colorant, and further performs an under color removal process (UCR process).
, A digital signal of any of C, M, Y, and K is output.

Under the control of the IPU control unit 400, the selector 204 selects one of the signal from the color correction unit and the signal from the pattern generation unit and outputs it to the gradation correction unit 205.

The tone correction section 205 corrects the density using a look-up table in accordance with the characteristics of the printer section 300.

The gradation processing unit 206 selects either the image signal output from the gradation correction unit 205 or the image signal output from the pattern generation unit, and performs gradation processing such as dither processing. To output C, M, Y, and K signals.
In the printer unit 300, C, M, Y,
Upon receiving the K signal, a color image is formed.

The image memory 207 holds the image data converted into the density by the density conversion unit 201, and performs sampling from the image data stored in the memory when performing tone correction.

The pattern generator 208 generates a test pattern for performing tone correction.

The IPU control section 220 controls the entire image processing section, sets parameters for each processing section, and the like. Also,
As will be described later, determination of the type of recording paper based on a read value of a blank portion of a test pattern sampled from image data in an image memory, and target tone characteristics from a plurality of target tone characteristics stored in an internal ROM or the like , Calculation of a new gradation correction curve, and setting to the gradation correction unit.

Next, an example of a test pattern will be described with reference to FIG. The test pattern includes CMYK in which the density for measuring the output characteristic of the printer unit 300 is changed in a plurality of steps.
Each color patch 801 and a mark 802 indicating the direction in which a document is set are formed. A portion where the test pattern is not formed is used as a blank portion in a sheet determination described later.

Next, the processing procedure of gradation correction will be described with reference to FIG. When performing tone correction, first, the operation unit 50
The gradation correction function is selected by 0 (step S1). Next, a correction test pattern for performing gradation correction is output (step S2). Next, the output test pattern is set at a predetermined position on the platen (step S3),
A pattern reading process is performed (step S4). The read values of the patches sampled from the image memory 207 are temporarily stored in a buffer such as a RAM. If an error in the read value is detected due to a shift in the set position of the test pattern (step S5 / NO), a message for resetting the test pattern is displayed on the display unit, and the test pattern is set to the correct read position. (Step S6).

When the reading of the test pattern is completed normally (step S5 / YES), the paper is determined and the target gradation characteristic is selected (steps S7 and S8). The details will be described later. When the selection of the target value is completed, a correction curve is calculated from the target value and the read value (step S9). This can be realized, for example, by the method described in JP-A-9-107477.

When the calculation of the correction curve is completed, the previous correction curve is stored as the previous value (step S10), a new correction curve is set in the gradation correction section, and the automatic gradation correction is completed (step S11). ).

Next, the processing procedure of gradation correction and paper determination will be described with reference to FIG. The paper determination is performed at the same time as reading a test pattern without any pattern (a blank portion of the paper) and based on the RGB read data (step S20).

First, it is determined whether or not the sheet is recycled paper (step S21). Some types of recycled paper are slightly yellower in color than plain paper or specialty paper. If the B data is somewhat lower than the R and G data, it is determined to be recycled paper. (Step S21 / YES), target gradation characteristics for recycled paper are used for gradation correction (step S23). The determination condition is, for example, ((R−B> Th
1) and (GB> Th2)). In addition, Th
1, Th2 is a preset threshold value.

If it is determined that the paper is not recycled paper (step S21 / NO), it is determined whether or not the paper is overseas paper (step S22). Some overseas papers are slightly bluer in color than plain paper or specialty paper. If the B data is somewhat higher than the R and G data, Judge (step S22 / YES),
The target gradation characteristic for overseas paper is used for gradation correction (step S24). The determination condition is, for example, ((BR−Th> Th
3) and (BG> Th4)). Th3, Th
4 is a preset threshold value.

If it is determined that the paper is not an overseas paper (step S22 / NO), it is determined that the paper is plain paper or special paper, and the target gradation characteristic for plain paper is used for gradation correction (step S25). . If it is possible to distinguish the RGB read data between the plain paper and the special paper, it may be possible to make a further determination and select different target tone characteristics.

After the end of the determination, the above-mentioned correction curve is calculated using the selected target gradation characteristic (step S26).

As described above, in the present embodiment, a plurality of target gradation characteristics are held and can be selected from among them. Therefore, by changing the target gradation characteristics to be selected corresponding to the recording paper, various target gradation characteristics can be obtained. On the other hand, gradation and gray balance adjustment suitable for the paper can be performed.

Further, means for determining the recording paper is provided,
To automatically select the target gradation characteristic corresponding to the paper,
There is no need for the user to select the target gradation characteristic according to the recording paper used.

Further, since the recording paper is determined from the read value of the margin portion of the test pattern, it is possible to perform an adjustment suitable for the paper to be used without adding a dedicated paper determination device or a special adjustment procedure.

Next, an embodiment of the image forming system of the present invention will be described. FIG. 5 shows a system configuration of the present embodiment.

As shown in FIG. 1, the image forming system according to the present embodiment includes an image forming apparatus 20 such as a plurality of copying machines.
And a central controller 10 for managing these image forming apparatuses 20.

The image forming apparatus 20 is a copier having an image reading section, an image processing section, an image forming section, and the like, and has a gradation correcting function.

The central controller 10 controls each image forming apparatus 20
, And control of each image forming apparatus 20 by issuing a control command.

The image forming apparatus 20 and the central control unit 10 are connected by a communication line 30 such as a local area network, and exchange various control commands and data.

Next, the image forming apparatus 2 will be described with reference to FIG.
0 will be described in detail. Note that the same devices as those of the above-described image forming apparatus are denoted by the same reference numerals, and description thereof is omitted.

The image forming apparatus 20 of this embodiment has a communication control unit 800. The communication control unit 800 controls transmission and reception of data with the central control device 10.

Next, referring to FIG.
0 will be described. The description of the apparatus that performs the same processing operation as the image forming apparatus 20 of the first embodiment will not be repeated.

The IPU control unit 220 of this embodiment controls the entire image processing unit, sets parameters for each processing unit, and the like. Further, a new gradation correction curve is calculated from the image reading value of the test pattern sampled from the image data in the image memory 207 and reference data stored in an internal ROM or the like, and is set in the gradation correction unit 205. . When the reading needs to be transmitted to the central control unit 100, the data of the reading is transmitted to the system control unit 400. System control unit 400 receiving transmission data
Passes the data to the communication control unit 800, and the data is transmitted from the communication control unit 800 to the central control device 10. Further, it is determined whether or not the image is within a state range to be described later from the image reading value of the test pattern sampled from the image data in the image memory and the state determination range data stored in the internal ROM or the like. The correction data from the central control device 10 received by the communication control unit 800 is acquired from the system control unit 400 and set in the gradation correction unit 205.

In this embodiment, the test pattern shown in FIG. 3 is used.

Next, referring to FIG.
An example of the relationship between the read value and the written value of each patch of the test pattern at the time of the state determination of 0 is shown. The result of the determination is a normal range of variation (hereinafter referred to as a normal range), a range in which there is a problem with the density or gradation, and the state is considered to be deteriorated (hereinafter referred to as a danger range), an excessive or insufficient density, There are three types of ranges (hereinafter referred to as abnormal ranges) in which problems can occur if tone correction is performed due to inversion or the like.

The writing level of each patch of the test pattern has an upper limit value and a lower limit value of a read value in a normal range and a dangerous range, respectively. If the read value falls between the upper limit value and the lower limit value of the normal range, the normal range , Not in the normal range,
If it falls between the upper limit and the lower limit of the dangerous range, the dangerous range is defined as an abnormal range.

Next, the processing procedure of gradation correction and state determination of the printer unit 300 will be described with reference to FIG. When performing the gradation correction, first, a gradation correction function is selected by the operation unit 500 (step S30). Next, a correction test pattern for performing gradation correction is output (step S31). Next, the output test pattern is set at a predetermined position on the document table (step S32), and the pattern is read (step S33). The read values of the patches sampled from the image memory are temporarily stored in a buffer such as a RAM. After the reading is completed, a determination process is performed (step S34).

First, it is determined whether or not it is within the normal range (step S35). If the result of the determination is that it is within the normal range (step S35 / YES), the correction curve is calculated (step S40). This can be realized, for example, by the method described in JP-A-9-107477.
When the calculation is completed, the correction curve is set in the gradation correction unit, and the gradation correction is completed (step S41).

If it is not within the normal range (step S35 / NO), it is determined whether it is within the danger range (step S36). If it is within the danger area (step S36 / YES), the read data is sent to the communication control unit 800 through the system control unit 400, and the read data is transmitted from the communication control unit 800 to the central control device 10 (step S36). S37). The danger area is
After the data transmission, the correction curve is calculated in the same manner as in the normal range (step S40), and the correction curve is sent to the tone correction unit when the calculation is completed. After the setting, the gradation correction is completed (step S41).

If it is not within the normal range or the danger range (step S35 / NO, and step S36 /
NO), since the value is within the abnormal range, the read value is sent to the communication control unit 800 through the system control unit 400, and the read data is transmitted from the communication control unit 800 to the central control device 10 (step S38). The central controller 10 calculates a correction curve suitable for setting in the image forming apparatus based on the received read data, and transmits the data to the image forming apparatus 20. Communication control section 800 of image forming apparatus 20
(Step S39) is sent to the IPU control unit 220 through the system control unit 400,
The settings are set in the gradation correction unit 205 by the U control unit 220, and the processing ends (step S41).

As described above, according to the present embodiment, the read value of the test pattern is sent to the central control unit 10 which manages the tone pattern when the tone correction is executed, so that the density state of the image forming apparatus 20 and the tone characteristic Status can be managed remotely.

When the deterioration of the state is detected from the read value of the test pattern, the read value is transmitted to the central control unit 10. Therefore, the state of the image forming apparatus 20 is reduced while the number of data transmission from the image forming apparatus 20 is reduced. Can be managed.

When an abnormal state is detected from the read value of the test pattern, the central control unit sets the gradation correction data. It is possible to prevent an abnormal test pattern from being read and resulting in an abnormal correction result.

The above-described embodiment is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

[0067]

As is apparent from the above description, since the image forming apparatus of the present invention can hold a plurality of target gradation characteristics and can select from them, the selection can be made according to the recording paper. By changing the target gradation characteristics to be performed, it is possible to adjust gradation and gray balance suitable for various types of paper.

Since the target gradation characteristic corresponding to the paper is selected by the means for determining the recording paper, it is not necessary for the user to select the target gradation characteristic according to the recording paper to be used.

Further, since the recording paper is determined from the read value of the margin portion of the test pattern, it is possible to perform an adjustment suitable for the paper to be used without adding a dedicated paper determining means or a special adjusting means.

Further, in the image forming system of the present invention, the read value of the test pattern is transferred to the processing device for managing the tone correction when the tone correction is executed. Can be managed remotely.

When the deterioration of the state of the image forming means is detected from the read value, the data is transmitted to the processing device. Therefore, the management of the image forming device is performed while reducing the number of data transmissions from the image forming device to the processing device. It can be done with the device.

Further, when an abnormality is detected from the read value of the test pattern, the processing apparatus can set the gradation correction data of the image forming apparatus. In this case, it is possible to prevent abnormal test patterns from being read and abnormal correction being performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of an image processing unit.

FIG. 3 is a diagram illustrating an example of a test pattern.

FIG. 4 is a flowchart showing an operation procedure.

FIG. 5 is a flowchart showing an operation procedure.

FIG. 6 is a diagram illustrating a system configuration of an image forming system.

FIG. 7 is a block diagram illustrating a configuration of the image forming apparatus.

FIG. 8 is a diagram illustrating a relationship between a read value and a write value of each patch of a test pattern.

FIG. 9 is a flowchart showing an operation procedure.

[Explanation of symbols]

 Reference Signs List 10 Central control device 20 Image forming device 100 Scanner 200 Image processing unit 300 Printer unit 400 System control unit 500 Operation unit 600 Display unit 700 ADF 800 Communication control unit

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Claims (6)

[Claims] An image reading unit that optically scans a document to convert the document into an image signal; an image processing unit that performs image processing on the image signal read by the reading unit; An image forming unit that forms an image based on an image signal; a test pattern generating unit that generates a test pattern signal for obtaining a gradation characteristic of the image forming unit; and a plurality of target image forming units. Storage means for storing tone characteristics; selecting means for selecting a target tone characteristic from the plurality of target tone characteristics; reading of a test pattern output by the image forming means and read by the image reading means A tone correction unit for correcting the tone characteristics of the image formation from the values and the target tone characteristics selected by the selection unit. Location. 2. The image forming apparatus according to claim 1, further comprising a determination unit configured to determine a type of the recording paper, wherein the selection unit selects a target gradation characteristic based on a determination result of the paper determination unit. apparatus. 3. The image forming apparatus according to claim 2, wherein the paper determination unit determines a type of the recording paper based on a read value of a blank portion of the test pattern. 4. An image reading unit for optically scanning a document to convert the image into an image signal, an image processing unit for performing image processing on the image signal read by the reading unit, and an image processed by the image processing unit Image forming means for forming an image based on a signal; test pattern generating means for generating a test pattern signal for obtaining gradation characteristics of the image forming means; target gradation characteristics of the image forming means A storage unit for storing the test pattern output from the image forming unit and read by the image reading unit, and a target value of the gradation characteristic stored in the storage unit. A tone correction means for correcting the tone characteristics of the test pattern, and when the tone correction is performed by the tone correction means, the test pattern read by the reading means is An image forming apparatus comprising: a communication unit that transmits a read value; and a processing device that manages a read value of the test pattern transmitted by the communication unit of the image forming device. system. 5. The image forming apparatus according to claim 1, further comprising: a detecting unit configured to detect deterioration of the image forming unit based on a read value of the test pattern. 5. The image forming system according to claim 4, wherein, when the deterioration of the test pattern is detected, the read value of the test pattern is transmitted to the processing unit. 6. The image forming apparatus according to claim 1, further comprising: a second detecting unit configured to detect an abnormality of the image forming unit from a read value of the test pattern. Transmitting the read value of the test pattern to the processing device, the processing device creates tone correction data based on the transmitted read value, and transmits the correction data to a corresponding image forming apparatus; The image forming system according to claim 4, wherein the forming apparatus sets the received gradation correction data in the gradation correction unit.