JP5365332B2 - Image forming apparatus, correction method, program, and recording medium - Google Patents

Description

  The present invention relates to an image forming apparatus, a correction method, a program, and a recording medium, and more particularly to an image forming apparatus, a correction method, a program, and a recording medium that perform gradation correction automatically at a specific timing and stabilize an output image.

  In a multi-function machine using an electrophotographic system, the process such as development, transfer, and fixing varies with the environment and time, and the output density characteristics tend to change. By adjusting various process conditions, stable output characteristics were ensured. However, for example, in a method of forming a patch on a photoconductor and measuring and adjusting the toner density, it is not possible to accurately obtain the characteristics of the subsequent transfer and fixing, so that the accuracy may not be sufficient. For this reason, this multifunction device has an automatic color correction (ACC) function that outputs a gradation correction pattern with a printer, reads it with a scanner, and corrects the gradation based on the read value. (See Patent Document 1).

  In order to maintain a stable image even if the interval of gradation correction increases, it has a means to detect environmental fluctuations and predicts fluctuations in image quality that are affected by environmental fluctuations from measured data of images that have been implemented in the past. And the method of correcting is disclosed (see Patent Document 2).

  However, the current automatic gradation correction (ACC) prints the same number of test patterns as the number of gradation processing types and reads the same number as the gradation processing types, so all applications are corrected. Has been a very complicated task for the user. There were also problems of using paper and toner, and the fact that not all users were implementing the ACC function because the users did not recognize the ACC function.

  The present invention has been made in view of such a situation, and an object thereof is to automatically perform gradation correction at a specific timing to stabilize an output image.

The image forming apparatus according to the present invention, outputs a test pattern, and generates a read data by reading the test pattern, the tone correction means for performing gradation correction process based on the read data, the engine Engine adjustment means for generating engine adjustment data by adjusting, engine adjustment data generated by adjusting the engine, and test pattern reading data for adjustment performed immediately after adjustment of the engine in automatic gradation correction And a storage means for storing the data in association with each other, and when the engine adjustment is performed at a predetermined timing and the predetermined engine adjustment data is output, the engine adjustment data stored in the storage means Selection to select the engine adjustment data closest to the predetermined engine adjustment data It includes a stage, the said gradation correction means, based on the adjusting test pattern reading data associated with the closest engine adjustment data, and performs the gradation correction process.

The correction method according to the present invention includes outputting a test pattern, generating read data by reading the test pattern, performing gradation correction processing based on the read data, and adjusting the engine A process of generating engine adjustment data, engine adjustment data generated by adjusting the engine, and test pattern reading data for adjustment performed immediately after adjustment of the engine in automatic gradation correction are associated with each other When the engine adjustment is performed at a predetermined timing and the predetermined engine adjustment data is output, the engine adjustment closest to the predetermined engine adjustment data among the stored engine adjustment data is output. Data selection process and the closest engine adjustment data. Based on Tagged adjusting test pattern reading data, characterized in that it comprises a and a step of performing the tone correction processing.

A program according to the present invention outputs a test pattern to a computer of an image forming apparatus, generates read data by reading the test pattern, and executes a gradation correction process based on the read data; Processing for generating engine adjustment data by adjusting the engine , engine adjustment data generated by adjusting the engine, and test pattern reading data for adjustment performed immediately after adjustment of the engine in automatic gradation correction Are stored in association with each other, and when the engine is adjusted at a predetermined timing and the predetermined engine adjustment data is output, the predetermined engine adjustment is selected from the stored engine adjustment data. The process of selecting the engine adjustment data closest to the data and Nearest based on adjusting test pattern reading data associated with the engine adjustment data, characterized in that to realize the process for executing the tone correction process.

The recording medium according to the present invention is a computer-readable recording medium for recording the processing of the program according to the present invention.

  According to the present invention, it is possible to automatically perform gradation correction at a specific timing and to stabilize the output image.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is a figure for demonstrating the data storage which concerns on embodiment of this invention. It is a figure for demonstrating regarding the automatic gradation correction (ACC) which concerns on embodiment of this invention. FIG. 6 is a diagram for describing printer γ correction of the image processing unit 2 provided in the image forming apparatus according to the embodiment of the present invention. It is a figure for demonstrating in-flight ACC which concerns on embodiment of this invention. It is a figure for demonstrating the process control data and data selection which concern on embodiment of this invention. It is a figure for demonstrating the outline of the data search from the memory | storage part 8 which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement process which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement process which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement process which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement process which concerns on embodiment of this invention. It is a flowchart which shows the operation | movement process which concerns on embodiment of this invention. It is a figure for demonstrating the case where only a solid density part at the time of engine adjustment which concerns on embodiment of this invention is used for correction | amendment.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

  In this embodiment, by storing the ACC pattern data and the engine adjustment data when it is output in association with each other, the stored data is referred to when the engine adjustment is performed, and the engine adjustment data is selected and selected. The correction γ is calculated from the ACC pattern data associated with the engine adjustment data and the currently set ACC γ, and gradation correction is performed. Therefore, even if the user does not perform the gradation correction operation, it is possible to automatically perform corrections including gradation processing, transfer / fixing, and the like at a specific timing. In addition, there are effects that automatic gradation correction can be performed without paper output and that the present configuration can be implemented without increasing costs.

(Constitution)
FIG. 1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention. It comprises a reading unit 1, an image processing unit 2, a writing unit 3, an operation unit 4, a display unit 5, a CPU (Central Processing Unit) 6, a memory 7, and a storage unit 8.

  The reading unit 1 is a scanner or the like that reads image data from a document.

  The image processing unit 2 includes a test pattern generation unit 21, a correction unit 22, and a printer γ correction unit 23, and performs automatic gradation correction (ACC: Auto Color Correct) of image data.

  The writing unit 3 includes a voltage detection unit 31, a concentration detection unit 32, and an engine adjustment unit 33. Examples of engine adjustments include process control (process control) and in-flight ACC. A process controller detects a pattern on a photoconductor in a multifunction machine using an electrophotographic method, and adjusts that an output density characteristic changes due to an environment in a process or a change with time. The in-flight ACC will be described later.

  The operation unit 4 is an input device for a user to perform an operation. The display unit 5 is a display device configured with a liquid crystal display or the like. The operation unit 4 may include the display unit 5 and may be configured from various keys, a touch panel on the display unit, and the like.

  The CPU 6 includes a data association unit 61, a data reference unit 62, a weighting unit 63, a correction calculation unit 64, and a correction execution determination unit 65.

  The memory 7 is a volatile memory, for example, using a flash memory or the like, temporarily holding information generated at the time of executing the engine adjustment, and using it when comparing with accumulated data.

  The storage unit 8 is a non-volatile memory, and uses, for example, an HDD (Hard Disk Drive) to store ACC data. Specifically, engine adjustment data performed immediately before adjustment test pattern output and adjustment test pattern read data performed immediately after engine adjustment are stored in association with each other. That is, the ACC pattern data at the time of design and the engine adjustment data when it is output, and the ACC pattern data when the user executes ACC and the engine adjustment data when it is output are also stored.

(Operation processing)
The storage unit 8 of the image processing apparatus according to the present embodiment stores past engine adjustment data and adjustment test pattern read data (also referred to as ACC data) in association with each other. Therefore, first, accumulation of engine adjustment data and the like will be described below.

<Storage of engine adjustment data, etc.>
The engine adjustment is performed by the engine adjustment unit 33 of the writing unit 3 according to an operation instruction from the operation unit 4 by the user, and the engine adjustment data is temporarily stored in the memory 7.

  After the engine adjustment is completed, an adjustment test pattern is generated by the image processing unit 2, and the adjustment test pattern is output from the writing unit 3 (for example, printed on a paper medium and output). After the output is completed, a message that prompts the reading unit 1 to read the adjustment test pattern is displayed on the display unit 5. The user sets the output adjustment test pattern in the reading unit 1 according to the message, and the reading unit 1 reads the adjustment test pattern. The adjustment test pattern read data is also temporarily stored in the memory 7.

  Subsequently, the data association unit 61 of the CPU 6 associates the engine adjustment data performed immediately before the adjustment test pattern output with the adjustment test pattern read data performed immediately after the engine adjustment, and stores them in the storage unit 8. Is done.

  It should be noted that a plurality of pieces of engine adjustment data and adjustment test pattern read data associated with each other can be stored in advance in the storage unit 8 before product shipment.

  FIG. 2 is a diagram for explaining data accumulation. Immediately before the adjustment test pattern is output, the engine adjustment operation is performed, and the two data (ACC data and engine adjustment data) are associated with each other and stored in the storage unit 8 as one combination. The storage unit 8 stores a plurality of similar data (combination N in FIG. 2).

  A combination of ACC data and engine adjustment data can be stored for each color (CMY).

  In addition, the association data stored in the storage unit 8 can always store data output from the corresponding machine, and can also store data generated and used in advance at the time of design. It is possible to use a plurality of correspondence data without performing ACC many times.

<Automatic gradation correction (ACC)>
Here, the automatic gradation correction will be described in detail. ACC (Automatic Gradation Correction) outputs the pattern for ACC after adjusting the state on the engine side to become the engine target output.

  FIG. 3 is a diagram for explaining automatic gradation correction (ACC). First, when a button for “execution” of automatic gradation correction is touched by an operation from the operation unit 4 by the user, ACC is executed. Specifically, first, engine adjustment is performed, and a test pattern for adjustment is output after completion of the engine adjustment process.

  The user installs the output adjustment test pattern in the reading unit 1 (for example, a scanner), and gives an instruction to start reading. Reading is started by the reading unit 1, and the CPU 6 calculates ACCγ from the read data and reflects it in the image processing unit 2 (see FIG. 4 of the ACCγ unit) to update the gradation correction. To be implemented.

  Details of the printer γ correction unit 23 provided in the image processing unit 2 will be described with reference to FIG. FIG. 4 is a diagram for explaining the printer γ correction of the image processing unit 2 provided in the image forming apparatus according to the embodiment of the present invention. The image processing path illustrated in FIG. 4 is an image processing path extracted with respect to the printer γ correction unit 23 of the image processing unit 2.

  The printer γ correction unit 23 includes image processing paths of difference correction γ, ACC γ, image quality correction γ, and gradation processing. Note that the order of the γ processing of the printer γ correction unit is as shown in FIG. 4 for convenience, but the order is not limited. The same function can be obtained by constantly updating ACCγ without having the difference correction γ.

  With “image quality correction γ”, different γ correction can be performed for each image quality mode (character mode, photo mode, character photo mode, etc.). “ACCγ” is a γ correction for bringing the engine state closer to the target during ACC execution. That is, “ACCγ” is γ for correcting the difference in consideration of the difference between the acquired ACC data and the ACC target when executing ACC. “Difference correction γ” searches past data close to that data when engine adjustment (procone etc.) is performed without executing ACC, and the current setting of ACCγ and ACCγ currently set This is γ correction for correcting the difference. In addition, “gradation processing” is image processing for artificially expressing gradation when engine output (1bit, 2bit, 4dit, etc.) has fewer gradations than input data (electronic data (8bit)). . For example, there are a dither method and an error diffusion method. Note that “image quality correction γ” and “gradation processing” are described for convenience in describing the image processing flow, and are not essential in the present embodiment.

  Next, the updating of the ACCγ table by reflecting the ACCγ calculated from the adjustment test pattern read data described above to the image processing unit 2 (ACCγ unit) will be described in detail.

  Although not shown, the printer γ correction unit 23 includes a difference correction γ table, a linear table, and an ACC γ table. The “difference correction γ table” is the difference correction γ in FIG. 4, the “linear table” is the γ correction parameter, and the “ACC γ table” is the ACC γ in FIG.

  In the present embodiment, if the correction amount exceeds the reference value by providing a reference value in advance, the difference correction γ is set to through (no γ correction is performed), and the ACCγ table itself is updated. Also, the ACC data (see FIG. 2) associated with the selected data is compared with the currently set ACC data, and the correction direction is the reverse direction (one γ is used to correct the data in a darker direction). On the other hand, when the other γ is a correction in the direction of thinning data, the difference correction γ is set to through (no γ correction is performed), and the ACCγ itself is updated.

  In other cases, the generated γ is reflected in the difference correction γ. Note that the difference correction γ can be set to the through setting according to a specific condition or request such as when ACC is executed or a user request.

<In-flight ACC>
As an example of engine adjustment, an in-machine ACC in which a test pattern is formed on a photoreceptor will be described. The in-machine ACC calculates the difference between the toner adhesion amount on the photoconductor and the target adhesion amount on the engine side, and performs adjustment in the writing unit so as to obtain the target adhesion amount. FIG. 5 is a diagram for explaining the in-flight ACC.

  FIG. 5A is a diagram showing an example of a test pattern used for engine adjustment (program control or in-flight ACC). In FIG. 5A, only black is shown, but the same applies to other colors (CMY and the like). Further, the number of gradations and the order of gradations of the test pattern shown in FIG. 5A are for convenience and are not particularly limited.

  FIG. 5B is a diagram illustrating an example of the configuration of the density detection unit 32. After the test pattern shown in FIG. 5A is formed on the photoconductor, it is configured as shown in FIG. 5B, that is, a light source (for example, LED (Light Emitting Diode) 102) and a light receiving element (for example, photo). Using a sensor 10 (an example of the density detector 32) including a transistor 101), light is emitted from a LED 102 to a test pattern formed on the photoconductor 12, and the irradiated light is formed on the photoconductor 12. Reflected from the pattern. The reflected light is received by a light receiving element such as the phototransistor 101 to measure the adhesion amount (or density) of the toner 11.

<Selection of optimum data from data stored in storage unit 8>
As described above, the storage unit 8 stores engine adjustment data and ACC data in association with each other. Therefore, in this embodiment, at the time of engine adjustment, three points of current engine adjustment data, accumulated engine adjustment data, and target engine data (also referred to as “procone target data”, preset target data). Using the relationship, the engine adjustment data satisfying a specific condition is searched from the stored engine adjustment data. Based on the difference between the ACCγ included in the stored ACC data in combination with (associated with) the searched engine adjustment data and the currently set ACCγ, a difference correction γ is calculated and tone correction is performed. It is characterized by that.

  First, when it is determined that engine adjustment is necessary due to the internal state of the engine, engine adjustment is performed by the engine adjustment unit 33 in the writing unit 3. Whether the engine adjustment is necessary is determined in the writing unit 3. The requirements can be considered variously, for example, the number of printed sheets and the temperature and voltage fluctuations in the machine.

  When the engine adjustment is completed, the adjustment data is sent to the memory 7. One data is selected from the data held in the storage unit 8 by the data reference unit 62 of the CPU 6. A correction γ is generated from the selected data by the correction calculation unit 64 and reflected on the image processing unit 2. Data selection will be described later.

  When generating the correction γ, the weighting unit 63 of the CPU 6 can weight the correction amount on the highlight part, the middle part, the shadow part, and the like. Further, after the correction execution determination unit 65 generates the correction γ, it is determined whether “the generated γ has no problem?”, “Whether printing is in progress”, and the like. Judgment is made as to which of ACC γ and difference correction γ (see FIG. 4) is reflected.

  Here, data selection (selection and search of optimum data) will be described in detail. In FIG. 6, the horizontal axis (X axis) is the development potential (difference between the development bias and the bright portion potential), and the vertical axis (Y axis) is the toner adhesion amount. The process control data can be expressed on two-axis coordinates using the toner adhesion amount and the development potential (development bias-light portion potential).

  For example, if the process control data (point A), process control target data (point T), and stored process control data (points B to F) are as shown in FIG. Find the straight distance between proc data (point A), target data (T) and BF.

  In the case of the above figure, the point D is first selected as a point close to T. Next, the relationship between the toner adhesion amount at points D and T and the relationship between the toner adhesion amount at points A and T are confirmed. Then, the toner adhesion amount is smaller at the point D than the target, whereas the toner adhesion amount is larger at the point A. In this case, since the reverse correction is performed, the point D is excluded from the candidates for the current correction. Similarly, the linear distance from B to F (excluding point D) is confirmed again, and point B is selected as a point close to target T. Similarly, comparing the amount of toner adhesion with the reference point, there is no problem (the amount of toner adhesion is larger than the target for both points A and B), so there is no reverse correction. The associated ACC data will be used.

  It should be noted that it is also possible to use the point that places the highest importance on correction (or the point with the highest accuracy of engine data) by using a weighting function as the process control data to be used. The points that place the highest importance on correction and the points with the highest accuracy are, for example, contents set in advance when the designer designs.

  It is also possible to make the engine adjustment pattern and the ACC pattern the same, connect the data of the respective gradation patches in a ratio of 1: 1, select the data for each gradation patch, and perform correction. The processing for each gradation patch will be described later with reference to FIG.

  FIG. 7 is a diagram for explaining an outline of data retrieval from the storage unit 8. When the image forming apparatus (MFP: multi-function printer) performs engine adjustment, engine adjustment data X is output. The output of the engine adjustment data X is a trigger, and the CPU 6 acquires combination data from the storage unit 8 and compares it with the currently performed engine adjustment data X, and 1 out of the data stored in the storage unit 8 Choose one combination. The correction γ is generated using the ACC data of the selected combination. Whether the correction can be performed is determined from the generated correction γ and the current engine state (whether or not the job is being executed). If the correction can be performed, the correction γ is reflected in the image processing unit 2. If correction is rejected, the correction is not performed and the process is terminated.

  Next, operation processing according to the present embodiment will be described in detail using a flowchart.

Example 1
FIG. 8 is a flowchart showing an operation process according to the embodiment of the present invention. Procon, which is an example of engine adjustment, triggers this flow. That is, when it is determined that the process control is executed (step S1 / Yes), the process control operation is executed (step S2). The process control data can be expressed on two-axis coordinates using the toner adhesion amount and the development potential (development bias-light portion potential) (see FIG. 6).

  The process control is executed (step S2), adjusted so as to be the target of the control unit included in the writing unit, and when it becomes the target, the process control is successful (step S3 / Yes), and the data of the executed control unit (data A) ) Is acquired (step S4). If the target of the control computer included in the writing unit is not adjusted many times, the control computer fails (step S3 / No). It is determined by a value determined in advance by the writing unit whether or not the process control fails when the process control fails continuously (step S3 / No). When the process control fails (step S3 / No), it waits for the process control to be executed again.

  A linear distance between the acquired process control data A and the stored data, that is, each process control data stored in the storage unit 8 is calculated. The one having the shortest linear distance (also referred to as “data MS”) is selected (step S6).

  Next, the difference (T−A) in the toner adhesion amount between the target data T of the process computer and the data A is calculated (TF1) (step S7).

  Similarly, the difference (T-MS) in the toner adhesion amount between the target data T of the process computer and the data MS is calculated (TF2) (step S8).

  When the product of these two data (TF1 × TF2) becomes negative (step S9 / No), the selected data is not subject to correction in the current correction and cannot be listed as a candidate (step S10).

  When the product of these two data (TF1 × TF2) becomes positive or 0 (step S9 / Yes), the associated ACC data is compared with the currently set ACC data (step S11). The difference is calculated (step S12), and a correction γ is generated (step S13).

  Subsequently, it is confirmed that there is no portion where the gradation is reversed in the γ data generated (step S14).

  If there is a tone reversal (step S14 / No), the process returns to the standby state without correction (step S16).

  If there is no gradation inversion (step S14 / Yes), correction is performed (step S15) and the process returns to the standby state (step S16).

  As described above, it is possible to automatically perform gradation correction without outputting and reading a test pattern (conventional ACC operation) when performing engine adjustment.

  In addition, it is possible to select optimum data from the stored data without performing a correction opposite to the original correction direction (correction for thickening or correction for thinning).

  In addition, the generated correction γ table can prevent abnormal images due to gradation inversion.

(Example 2)
FIG. 9 is a flowchart showing an operation process according to the embodiment of the present invention. The flow from step S20 to S29, that is, the determination of the data MS is the same as in FIG.

  The ACC data associated with the data MS is compared with the currently set ACCγ (step S30), and the direction to be corrected is opposite to the currently set correction (current ACCγ). It is confirmed whether or not correction has been made (step S31). The reverse correction is, for example, when ACCγ is set to correct in the dark direction in order to bring the image closer to the target, so that the result of this time is closer to the target, so the γ table is corrected in the direction in which the image becomes thinner. This is the case.

  If the correction is reversed (step S31 / Yes), ACCγ is generated based on the currently selected data (step S38), and after confirming that there is no gradation inversion (step S39 / Yes), the difference correction γ Is updated to a linear table (step S40), and the ACCγ table is updated (step S41).

  If the correction is not reversed (step S31 / No), the ACC data associated with the data MS is compared with the currently used ACC data, resulting in a correction exceeding a predetermined reference amount. Whether or not (step S32).

  If the correction exceeds the reference amount (step S32 / Yes), ACCγ is generated based on the currently selected data (step S38), and after confirming that there is no gradation inversion (step S39 / Yes), the difference The correction γ is updated to the linear table (step S40), and the ACCγ table is updated (step S41).

  If the reference amount is not exceeded (step S32 / No), a difference from the currently set ACCγ is calculated (step S33), a difference correction γ is generated (step S34), and reflected in the difference correction γ part ( Steps S35 and S36).

  When storing ACCγ, to save storage capacity, data is not stored for all points (256 for 8-bit), but specific points (the same number of data as the gradation pattern of the ACC pattern) Is stored, and interpolation is performed as necessary to generate data for all points (256 for 8 bits). Similarly, when comparing data differences, a difference between specific points is calculated, and then an interpolation operation is performed. For this reason, the larger the correction amount in the difference correction γ, the greater the influence of the difference due to the interpolation operation on the currently set ACCγ. For this reason, there is a possibility that correction will be performed more than the amount to be adjusted. Therefore, such a state can be avoided by applying correction γ to ACCγ according to conditions such as a correction amount.

  According to the above embodiment, the larger the correction amount in the difference correction γ, the greater the influence of the difference due to the interpolation calculation on the currently set ACC γ, and the state where the correction is performed more than the amount to be adjusted. It can be avoided.

  Further, there is a risk that the larger the correction amount, the greater the effect of the correction γ on the image. However, this risk can be avoided by determining whether or not to perform correction based on the magnitude of the correction amount. .

(Example 3)
FIG. 10 is a flowchart showing an operation process according to the embodiment of the present invention. The flow from step S45 to S59 and S64, that is, the determination of the data MS and the update of either ACCγ or difference correction γ is the same as in FIG. The flow shown in FIG. 10 is a flow relating to a case where engine adjustment is performed during continuous printing.

  After the correction γ or ACCγ is created, the presence / absence of gradation inversion is confirmed (steps S60 and S65). Return (step S70).

  If there is no gradation inversion (steps S60 / Yes, S65 / Yes), it is checked whether the engine is operating (printing), and if printing is in progress (steps S60 / Yes, S66 / Yes), the job Is waited for and γ is not updated (steps S63 and S68). After the printing operation is completed, the calculated correction γ or ACCγ is applied (steps S63, S68, and S69).

  If printing is not in progress (steps S60 / No, S66 / No), correction is performed immediately (steps S63, S68, and S69).

  If correction γ is applied during printing, depending on the set γ parameter, a large image change may occur immediately before and immediately after γ reflection. If this phenomenon occurs in the same document of the same job, it may be a complaint from the user. Therefore, according to the above embodiment, it is possible to prevent the image quality from changing abruptly during the continuous printing by waiting for the application of γ correction during printing.

Example 4
FIG. 11 is a flowchart showing an operation process according to the embodiment of the present invention. The flow from step S75 to S85, that is, the determination of the data MS and comparison with the currently set ACC data is the same as in FIGS.

  If the correction is the reverse of the current ACCγ (step S86 / Yes), a message prompting the implementation of ACC is displayed on the display unit (step S88), and the process returns to the standby state (step S95). Similarly, when the correction amount exceeds the reference amount (step S87 / Yes), a message prompting the implementation of ACC is displayed on the display unit (step S88), and the process control standby state is returned (step S95).

  If the correction is not the reverse of the current ACCγ (step S86 / No) and the correction amount does not exceed the reference amount (step S87 / No), the correction γ is generated, and the tone reversal of the correction γ is confirmed and printed. It is confirmed whether or not it is in progress, the correction γ is updated, and the process returns to the standby state (steps S89 to S95).

  According to the embodiment, it is possible to prevent the image quality from changing suddenly during the continuous printing.

(Example 5)
FIG. 12 is a flowchart showing operation processing when data is selected and correction is performed for each gradation patch.

  The data corresponding to each gradation patch of the test pattern is searched from the stored data, that is, the combinations stored in the storage unit 8 by steps S104 to S110 (data selection unit) in FIG. Is equal to the same number as the number of gradation patches (n) of the test pattern (in FIG. 12, n = 15 is taken as an example). The data corresponding to each gradation patch of the test pattern is engine adjustment data / ACC data associated with each gradation patch at a ratio of 1: 1. In the present embodiment, searching for the past data (accumulated data) closest to each of the 15 gradation patches will be described. That is, the shortest data is selected from the n-th gradation patches of the stored process control data for the n-th gradation patch A (n) of the currently executed process control data.

  If the same number of data as the number of gradation patches is not available (step S111 / No), the process returns to the top of the data selection unit and searches for the next gradation patch. When the same number of data as the number of gradation patches is obtained (step S111 / Yes), the ACC data respectively associated with each selected data (data MS), the currently set ACC data, Are compared (step S113).

  If all the correction directions are the same (step S114 / Yes) and there is no data whose correction amount exceeds the reference amount (step S115 / Yes), a correction γ is generated and correction is performed (steps S116 to S116). S121).

  If there is even one piece of data in which the correction direction is reversed (step S114 / No), the process is executed in a flow for updating ACCγ (steps S122 to S127).

  In addition, when there is data in which even one of the selected data causes the correction amount to exceed the reference amount (step S115 / No), the process is executed in a flow for updating ACCγ (steps S122 to S127). ).

  According to the above-described embodiment, correction for each gradation can be performed, so that correction with higher accuracy can be realized. Further, since correction can be performed for each color, correction with higher accuracy can be realized for each color. Further, correction can be performed without losing gray balance.

(Example 5)
FIGS. 13A and 13B are diagrams for explaining a case where only the solid density portion at the time of engine adjustment is used for correction.

  The optimum data is searched and selected from the data stored in the storage unit 8 at the time of engine adjustment (when the program control is successful) (selected under the conditions described in the flowcharts of FIGS. 8 to 12). Extracted data of solid density part of ACC data stored in association with selected data (ACC data includes information for each patch used at the time of ACC correction. For example, the number of patches is 15 levels. In this case, the 15-stage patch data is stored as the ACC data.) With respect to the currently set ACC correction point, only the solid density portion is replaced with the selected correction point (FIG. 13A). .

  Based on the replaced data, a correction γ is generated by performing an interpolation calculation (FIG. 13B). By calculating the difference correction γ from the correction γ and the currently set ACC γ and updating the difference correction γ, or by updating the currently set ACC γ to the generated correction γ, fluctuations in the shadow portion can be reduced. Emphasized correction can be performed.

  According to the above-described embodiment, the correction accuracy can be improved by using only the portion (solid density portion) where the engine adjustment value is most stable for correction.

  Note that the program for the CPU 6 to execute the processes shown in the flowcharts of the respective drawings constitutes a program according to the present invention. As a recording medium for recording the program, a semiconductor storage unit, an optical and / or magnetic storage unit, or the like can be used. By using such a program and recording medium in a system or the like having a configuration different from that of each of the above-described embodiments, and causing the CPU 6 to execute the program, substantially the same effect as the present invention can be obtained.

  Although the present invention has been specifically described above based on the preferred embodiments, it is needless to say that the present invention is not limited to the above-described ones and can be variously modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Reading part 2 Image processing part 3 Writing part 4 Operation part 5 Display part 6 CPU
7 Memory 8 Storage Unit 21 Test Pattern Generation Unit 22 Correction Unit 23 Printer γ Correction Unit 31 Voltage Detection Unit 32 Density Detection Unit 33 Engine Adjustment Unit 61 Data Association Unit 62 Data Reference Unit 63 Weighting Unit 64 Correction Operation Unit 65 Correction Execution Determination 65 Part

JP 2004-104712 A JP 2007-36411 A

Claims (17)

A gradation correction unit that outputs a test pattern, generates read data by reading the test pattern, and executes a gradation correction process based on the read data ;
Engine adjustment means for generating engine adjustment data by adjusting the engine;
Storage means for storing the engine adjustment data generated by adjusting the engine and the test pattern reading data for adjustment performed immediately after the adjustment of the engine in automatic gradation correction in association with each other;
When the engine is adjusted at a predetermined timing and the predetermined engine adjustment data is output, the engine adjustment data closest to the predetermined engine adjustment data is selected from the engine adjustment data stored in the storage means. Selecting means for selecting,
The image forming apparatus according to claim 1, wherein the gradation correction unit performs the gradation correction processing based on adjustment test pattern read data associated with the closest engine adjustment data .   The image forming apparatus according to claim 1, wherein the engine adjustment unit is a process control.   2. The image forming apparatus according to claim 1, wherein the engine adjusting unit forms a test pattern on the photosensitive member, reads the test pattern, confirms an engine state, and performs image correction.   4. The storage unit according to claim 1, wherein the storage unit stores the test pattern data in association with data of engine adjustment performed before or after a predetermined time for outputting the test pattern data. 2. An image forming apparatus according to item 1. Engine adjustment value target data including at least the toner adhesion amount and the difference between the development bias [V _B ] and the light portion potential [V _L ] (hereinafter, development potential | V _B −V _L |);
A linear distance calculating means for calculating a linear distance between two points on a two-dimensional coordinate comprising the toner adhesion amount and the development potential;
Toner adhesion amount comparing means for determining the amount of toner adhesion with the target data,
When referring to the engine adjustment data stored in the storage means at the time of engine adjustment, the amount of toner adhesion of the target data and the engine adjustment data stored in the storage means is compared, and when the engine adjustment is executed In the stored data that matches the amount of toner adhesion between the engine adjustment data and the target data, select the data that has the shortest linear distance from the engine adjustment data when the engine adjustment is performed, and perform tone correction. The image forming apparatus according to claim 1, wherein the image forming apparatus is implemented. Difference correction means for correcting a difference between γ data selected from the plurality of data stored in the storage means and the currently set ACC γ data;
Gradation inversion determination means for determining presence / absence of gradation inversion of the difference correction γ generated by the difference correction means,
6. The image forming apparatus according to claim 1, wherein whether or not the generated difference correction γ has gradation reversal is determined, and whether the difference correction γ is reflected is determined. The storage means stores engine adjustment data at the time of setting automatic gradation correction data,
Based on the engine adjustment data at the time of engine adjustment, the engine adjustment data stored in the storage means, and the set engine adjustment data at the time of automatic gradation correction set by the toner adhesion amount comparison means and the difference correction means. 7. The image forming apparatus according to claim 5, wherein the correction method is changed according to the difference between the respective toner adhesion amounts and the data. A weighting unit that performs weighting according to the toner adhesion amount;
8. The image forming apparatus according to claim 1, wherein the weighting unit weights the correction value according to a gradation having a different toner adhesion amount. 9.   9. The image forming apparatus according to claim 8, wherein the weighting unit performs correction using only density variation data of the solid density portion.   The image forming apparatus according to claim 1, wherein the storage unit stores the data output by the automatic gradation correction unit and the engine adjustment unit by dividing the data for each color. apparatus.   11. The image forming apparatus according to claim 10, wherein different data is referenced for each color from the storage unit. A correction execution determining means for determining the execution of the correction,
12. The image forming apparatus according to claim 1, wherein the correction is not performed when the selected data does not satisfy the determination criterion of the correction execution determination unit.   The image forming apparatus according to claim 12, wherein the determination criterion of the correction execution determination unit is whether printing is being executed. 13. The image forming apparatus according to claim 12, wherein the determination criterion of the correction execution determination unit is a difference calculated by the difference correction unit. Outputting a test pattern, generating read data by reading the test pattern, and executing a gradation correction process based on the read data;
Generating engine adjustment data by adjusting the engine;
Storing the engine adjustment data generated by adjusting the engine and the test pattern reading data for adjustment performed immediately after the adjustment of the engine in automatic gradation correction in association with each other;
A step of selecting engine adjustment data closest to the predetermined engine adjustment data from the stored engine adjustment data when the engine adjustment is performed at a predetermined timing and the predetermined engine adjustment data is output; When,
And a step of performing the gradation correction processing based on adjustment test pattern read data associated with the closest engine adjustment data . In the computer of the image forming apparatus,
A process of outputting a test pattern, generating read data by reading the test pattern, and executing a gradation correction process based on the read data;
Processing to generate engine adjustment data by adjusting the engine;
A process of associating and storing engine adjustment data generated by adjusting the engine and adjustment test pattern reading data that is performed immediately after adjustment of the engine in automatic gradation correction;
A process of selecting engine adjustment data closest to the predetermined engine adjustment data from the stored engine adjustment data when the engine adjustment is performed at a predetermined timing and the predetermined engine adjustment data is output. When,
A program for realizing a process of executing the gradation correction process based on adjustment test pattern read data associated with the closest engine adjustment data . The computer-readable recording medium which records the process of the program of Claim 16.

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