JP2013083861A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device by which, if printing stops in the course of a series of flow of automatic gradation correction, correction accuracy is not reduced and a waste of time, sheet, and toner is reduced.SOLUTION: In the case of restart after interruption of automatic gradation correction, control means performs control so that the interrupted gradation pattern is continuously formed as an image on a recording sheet a plurality of prescribed times.

Description

  The present invention relates to an image forming apparatus having an automatic gradation correction function.

  Patent Document 1 discloses an image processing apparatus in which an optical sensor is provided on a paper conveyance path in an image forming apparatus, and the gradation correction can be performed by reading the gradation correction pattern in accordance with the paper passage timing. Has been. In this method, the user only has to give an execution instruction for automatic gradation correction. That is, there is no need for a user operation in which the user manually reads the pattern-printed paper with a scanner.

  There is also an image forming apparatus that performs automatic gradation correction using a plurality of types of patterns according to a user's automatic gradation correction instruction. This is because the same number of patterns as the type of gradation processing are printed, and the same number of patterns as the type of gradation processing are read. In such an image forming apparatus, a plurality of types of patterns are processed in a series of flows in response to a single automatic gradation correction instruction from the user.

  Further, there is an image forming apparatus that prints the same type of pattern a plurality of times in succession and uses the read value of the last one pattern for tone correction. There is a tendency that the image of the printed matter is stabilized by continuously printing multiple times. Therefore, the accuracy of tone correction is improved by using the last one when the image is stable.

JP 2001-142345 A

  However, suppose that it is considered to perform automatic gradation correction using a method in which a plurality of types of patterns are used and each pattern is continuously printed a plurality of times. Assume that printing is stopped (interrupted) due to, for example, the absence of paper or a jam in the course of this automatic gradation correction flow. In this case, to recover, it is necessary for the user to prepare paper or remove the jam. Usually, the user notices that no paper or a jam has occurred, and then performs a user operation for recovery, so that a certain amount of time may pass. For this reason, when pattern printing is resumed after restoration, there is a problem that the effect of stabilizing the image by continuous printing is reduced if the printing stop time is long. In addition, if it is redone from the beginning of a series of flows, there is a problem that it takes time and wasteful consumption of paper and toner increases.

  The present invention has been made in view of the above problems, and the object of the present invention is to use automatic gradation correction by using a plurality of types of patterns and continuously printing each pattern a plurality of times. Therefore, the present invention provides an image forming system that can perform automatic gradation correction with high efficiency and high accuracy when printing stops.

In order to solve the above problem, an image forming apparatus according to the present invention includes a pattern generation unit that generates a plurality of gradation patterns for performing automatic gradation correction;
A recording unit that generates an image by transferring an image corresponding to the gradation pattern to a recording sheet, and a correction characteristic for determining a density correction characteristic of the recording unit by reading a gradation pattern image formed on the recording sheet An image forming apparatus comprising: a determination unit; and a correction unit for reflecting the density correction characteristic determined by the correction characteristic determination unit in image generation by the recording unit,
Further, the recording means is controlled so as to continuously generate the gradation pattern on the recording paper a predetermined number of times, and the gradation pattern image read in the last of the plurality of times is determined for density correction characteristics. Control means for controlling the correction characteristic determining means to be used for,
The control means is characterized in that when the automatic tone correction is resumed after being interrupted, the interrupted tone pattern is controlled so as to continuously generate an image on the recording paper a predetermined number of times.

  According to the invention of the present application, when printing is stopped halfway by automatic gradation correction using a plurality of types of patterns and printing each pattern a plurality of times continuously, the time required for redoing, paper or toner There is an effect that automatic gradation correction with high accuracy is possible while suppressing wasteful consumption efficiently.

1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment. It is a block diagram which shows the structure for performing gradation correction and printing. It is a figure which shows the example of a display of an operation screen. It is a flowchart which shows an automatic gradation correction process (calibration) (the 1). It is a flowchart which shows an automatic gradation correction process (calibration) (the 2).

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[Example 1]
<Device configuration>
FIG. 1 is a block diagram showing a configuration of an image forming apparatus as an embodiment of the present invention. In the figure, an image forming apparatus includes a reader unit A that reads an original image, and a printer unit B that reproduces (records) the original image on a recording sheet that is a recording medium, based on image data obtained by the reader unit A. It has.

  The reader unit A outputs image data obtained by reading the original image of the document to the printer unit B.

  The printer unit B prints the image data input from the reader unit A on a recording sheet.

  Hereinafter, the reader unit A and the printer unit B will be described with reference to FIG.

<Reader A>
The reader unit A includes a CPU 10, a RAM 11, a ROM 12, and an image processing unit 13.

  In the reader unit A, the CPU 10 controls the entire reader unit A including the following components in accordance with a program stored in advance in the ROM 12 or the like. The RAM 11 is used as a work area by the CPU 10, and the ROM 12 stores control programs, image processing parameters, and the like.

<Printer part B>
The printer unit B includes a printer control unit 21, a printer engine unit 22, an operation unit 30, and a display device 31.

  The printer control unit 21 includes a CPU 28, a RAM 23, a ROM 24, a copy counter 23 a, a test pattern storage area 24 a, an LUT 25, a PWM 26, a laser driver 27, and a pattern generator 29. And, it can communicate with the reader unit A, the printer engine unit 22 and the operation unit 30.

  In the printer control unit 21, the CPU 28 controls the entire printer unit B including the printer engine unit 22 and the following components in accordance with a program stored in advance in the ROM 24 or the like. Further, the CPU 28 communicates with the CPU 10 of the reader unit A to jointly perform operations such as copying. The RAM 23 is used as a work area by the CPU 28, and the ROM 24 stores control parameters and the like in addition to the control program. The ROM 24 includes a test pattern storage area 24a in which data corresponding to a predetermined test pattern is stored in advance (details will be described later).

  Further, the RAM 23 includes a copy counter 23a used in gradation correction processing (details will be described later).

  The look-up table (LUT) 25 is used to match the density of the original image and the density of the output image by so-called gamma correction. The LUT 25 is composed of, for example, a RAM or the like, and the contents of the data in the table are set by the CPU 28 in a calibration mode started by an operator instruction from the operation unit 30 (details will be described later). The LUT 25 has a plurality of areas for each gradation process.

  The pattern generator 29 generates image data for printing a test print, which will be described later, based on data corresponding to a predetermined test pattern stored in the test pattern storage area 24a during calibration, and a pulse width modulator (PWM) 26. Output to. The PWM 26 converts the image data into a pulse signal and inputs it to the laser driver 27. In accordance with the pulse signal transmitted from the laser driver 27, development and transfer are performed in the printer engine unit, the toner image is fixed, and the image is printed on the recording paper.

  The operation unit 30 includes a keyboard 31 and a touch panel (not shown) and a display 31 such as a liquid crystal display, and transmits an instruction from the operator to the CPU 28 and displays an operation mode and a state of the image forming apparatus. The display 31 includes a liquid crystal operation panel (touch panel display) with a push sensor as shown in FIG.

<Tone correction (printing example using LUT25)>
FIG. 2 is a block diagram for explaining gradation correction by the LUT 25 as an embodiment of the present invention.

  Hereinafter, an outline of processing for reading image data by the reader unit A and printing an image on a recording sheet by the printer unit B will be described with reference to FIG.

  In FIG. 2, the luminance data of the document image output from the CCD 200 is converted into frame sequential density data by the image processing unit 13. This density data is, for example, image data corrected according to the gamma characteristic of the printer unit B at the time of initialization such as at the time of factory shipment. The image data output from the image processing unit 13 is input to the LUT 25.

  The LUT 25 converts the density characteristics of the image data input from the image processing unit 13 so that the density of the original image matches the density of the output image. The image data output from the LUT 25 is input to the PWM 26.

  The image data subjected to gradation conversion by the LUT 25 is modulated by the PWM 26 circuit and sent to the laser driver 27. Then, in accordance with the pulse signal transmitted from the laser driver 27, development and transfer are performed in the printer engine unit, the toner image is fixed, and the image is printed on the recording paper.

  Incidentally, as shown in FIG. 2, image data for outputting a test print in the automatic gradation correction processing (calibration) is output from the pattern generator 29 to the pulse width modulator (PWM) 26. That is, based on data corresponding to a predetermined test pattern stored in the test pattern storage area 24a, image data for printing out a test print described later is output to the pulse width modulator (PWM) 26. Therefore, the LUT 25 is not used when a pattern is output in the calibration mode.

<Details of automatic gradation correction processing (calibration)>
Next, automatic gradation correction processing (calibration) performed by the image forming apparatus of the present embodiment will be described in detail.

  FIG. 4 is a flowchart showing automatic gradation correction processing as one embodiment of the present invention. The operation flow of each step in the flowchart shown in FIG. 4 is realized by the CPU 28 of the printer unit B executing a program in the ROM 24 and controlling each configuration of the printer unit B. This processing is started when the operator presses a setting key for an automatic gradation correction (calibration) mode provided on the display 31 of the operation unit 30, and the CPU 28 of the printer unit B performs control. . An example of the calibration mode start screen is shown in FIG. The number of copies area 303 in FIG. 3 is an area where the operator sets the number of copies to be printed per pattern. The number of copies can be set by the operator using a numeric key (not shown) of the operation unit 30. In this embodiment, the number of copies can be set in the range of 1 to 5, and here, an example in which the operator sets “3 copies” is shown. The “number of copies per pattern” set here is used in step S4007 in FIG. 4 described later to determine whether printing has been completed to the end of the set.

  When the operator presses the key 301 on the screen of the display unit 31 of the printer unit B and receives an instruction to execute automatic gradation correction, the CPU 28 pays attention to the first pattern in step S4001.

  In step S4002, the CPU 28 clears the copy counter 23a to zero. The number of copies counter 23a is used to hold how many copies of the pattern of interest are currently printed and read.

  In step S4003, the CPU 28 activates the pattern generator 29 and controls to print the pattern of interest. That is, a test print image is printed out from the printer unit B based on the data of the target pattern among the plurality of gradation processing patterns stored in the test pattern storage area 24a. As described above with reference to FIG. 2, the LUT 25 is not used when outputting a test print.

  In step S4004, the CPU 28 of the printer unit B controls the optical sensor in the printer engine unit 22 to sequentially read the test print images formed on the recording paper in accordance with the sheet passing timing. That is, the patch pattern is sequentially read in synchronization with the paper passing.

  In step S4005, the CPU 28 determines whether the reading is successful. Here, if the pattern is not printed and the optical sensor portion is not passed due to a paper jam or no paper, it is determined that the reading has not been successful. If the CPU 28 determines that the reading is successful, in step S4006, the CPU 28 increments the copy counter 23a by one. In step S4007, the CPU 28 determines whether printing of the target pattern is completed to the end of the copy. That is, if the copy counter 23a has reached the value specified by “Number of copies per pattern” in the number of copies area 303 of FIG. 3, the CPU 28 determines that “printing to the end of the copy has been completed”. If the CPU 28 determines that “printing has not been completed to the end of the copy”, the process returns to step S4003 to repeat the process from the printing of the target pattern. Each pattern is repeated until “number of copies per pattern” is printed.

  On the other hand, if the CPU 28 determines in step S4007 that the pattern of interest has been printed to the end of the set, the LUT 25 is set based on the read information read last in step S4008. Specifically, the level of the laser output level set by the PWM 26 in the laser driver 27 based on the pattern output value of the pattern generator 29 and the patch pattern density data after fixing on the recording paper obtained by the optical sensor. Tonal characteristic information (LUT25) is obtained. This is performed, for example, by the method described in Patent Document 1. More precisely, it is set in the area of the LUT 25 for the target pattern in the LUT 25.

  In step S4009, the CPU 28 determines whether the processing has been completed for all of the plurality of gradation processing patterns stored in the test pattern storage area 24a. Here, when the CPU 28 determines that the processing has been completed for all the patterns, the series of processing ends.

  On the other hand, if the CPU 28 determines in step S4009 that the processing has not been completed for all patterns, the next pattern is focused on in step S4010. In step S4011, the CPU 28 clears the copy counter 23a to zero. Then, returning to step S4003, the CPU 28 performs processing on the newly noticed pattern.

  On the other hand, when determining in step S4005 that the pattern reading has not succeeded, the CPU 28 advances the process to step S4012. In step S4012, the CPU 28 controls the display 31 to display an error message on the display 31 such as the cause of pattern printing failure (for example, “paper jam” or “no paper”), and the operator recovers (recovers). ). In step S4013, the CPU 28 determines whether the operator has recovered, and repeats the determination in step S4013 until recovery is performed. If recovered, the CPU 28 clears the copy counter 23a to 0 in S4014. In step S4003, the process of printing the target pattern is performed again from the beginning of the copy. That is, since the copy counter 23a is cleared to 0, even if some copies of the target pattern have been printed before recovery, printing is started from the first copy.

  As described above, when printing is interrupted during the automatic gradation correction of the method of correcting with the last one reading information obtained by printing a plurality of types of patterns each time a plurality of times, after recovering from the cause Then, the operation of printing the interrupted pattern is performed again from the first copy. In other words, each pattern is printed so as to be continuously printed a plurality of times and corrected with the stable reading information of the last time. Therefore, efficient and accurate automatic gradation correction can be performed.

[Example 2]
In the first embodiment, an example is shown in which, after printing is interrupted and recovered due to a paper jam or no paper, the operation is always performed so that printing / reading of the interrupted pattern is restarted from the first copy.

  Here, depending on the conditions at the time of recovery, it is possible to control and determine where to start again after recovery. For example, there is a method of changing where to redo depending on the time elapsed until recovery.

  In this embodiment, when the image is restored in a short time, the effect of image stabilization by continuous printing remains, so the process is repeated, and when it takes a long time, the effect of image stabilization is weakened. Start over. An example will be described in which if the time is between, the first pattern of the interrupted pattern is redone as in the first embodiment.

  Since the second embodiment is an extension of the first embodiment, only differences from the first embodiment will be described below.

<Details of automatic gradation correction processing (calibration)>
Next, an automatic gradation correction process (calibration) performed by the image forming apparatus according to the second embodiment will be described in detail.

  FIG. 5 is a flowchart showing an automatic gradation correction process as an embodiment of the present invention, which replaces FIG. 4 of the first embodiment. Processing different from FIG. 4 will be described below with reference to FIG.

  The operation flow of each step in the flowchart shown in FIG. 5 is realized by the CPU 28 of the printer unit B executing a program in the ROM 24 and controlling each component of the printer unit B. This processing is started when the operator presses a setting key for an automatic gradation correction (calibration) mode provided on the display 31 of the operation unit 30, and the CPU 28 of the printer unit B performs control. .

  If it is determined in step S4005 that the pattern reading has not succeeded, in step S4012, the CPU 28 controls the display 31 to display an error message indicating the cause of the pattern printing failure on the display 31, and the operator can recover ( Encourage recovery. The steps so far are as described in FIG.

  In step S5001, the CPU 28 starts measuring time from the interruption due to the occurrence of an error until the recovery. In step S5002 (similar to step S4013 in FIG. 4), the CPU 28 determines whether the operator has recovered, and repeats the determination in step S5002 until recovery. If recovered, in S5003, the CPU 28 determines whether or not the time elapsed from the interruption to the completion of recovery is less than the “predetermined time A”. If the CPU 28 determines that the time is less than the predetermined time A, the process returns to step S4003 to resume printing / reading the target pattern.

  On the other hand, if the CPU 28 determines in step S5003 that the time elapsed until the completion of recovery is not less than the “predetermined time A”, the process proceeds to step S5004. In step S5004, the CPU 28 determines whether or not the time elapsed until the completion of recovery is equal to or greater than the “predetermined time B”. Here, the predetermined time B is a time longer than the predetermined time A. If the CPU 28 determines in step S5004 that the predetermined time B or more has elapsed, the CPU 28 returns to step S4001 and performs control so that the process is started again from the beginning of the flow.

  On the other hand, if it is determined in step S5004 that the CPU 28 does not exceed the predetermined time B, the CPU 28 clears the copy counter 23a to 0 in step S5005 (similar to step S4014 in FIG. 4). This means that the time elapsed from the interruption to the completion of recovery is a predetermined time A or more and less than a predetermined time B. In step S4003, the process of printing the target pattern is performed again from the beginning of the copy. That is, printing is started again from the first copy of the pattern of interest.

  As described above, when printing is interrupted in the middle of automatic gradation correction in which a plurality of types of patterns are continuously printed a plurality of times and corrected based on the last read information of each pattern, the reason is After recovery, processing is changed according to the time elapsed from interruption to recovery. In other words, if recovery is made in less than the predetermined time A (short time), the process is repeated from the next, and if it takes longer than the predetermined time B (long time), the process is restarted from the beginning of the entire flow. If it is not less than the predetermined time A and less than the predetermined time B, the first pattern of the interrupted pattern is restarted as in the first embodiment. As described above, the restart point after restoration is controlled in consideration of the effect of image stabilization by continuous printing, so that automatic gradation correction with high efficiency and high accuracy is possible.

(Other examples)
In the above-described embodiment, an example of an apparatus having a reader unit and a printer unit as an image forming apparatus has been described. However, the present invention is not limited to this. Any device that can form an image, such as a printer, FAX, or MFP (Multi Function Peripheral), may be used.

10 CPU of reader part
11 RAM of reader section
12 ROM (reader part)
13 Image Processing Unit 21 Printer Control Unit 22 Printer Engine Unit 23 (Printer Unit) RAM
23a Copy counter 24 (printer section) ROM
24a Test pattern storage area 25 LUT
26 PWM (pulse width modulator)
27 Laser driver 28 (printer section) CPU
29 Pattern Generator 30 Operation Unit 31 Display

Claims (3)

Pattern generation means (29) for generating a plurality of gradation patterns for performing automatic gradation correction;
Recording means (26, 27, 22) for generating an image by transferring an image corresponding to the gradation pattern to a recording paper;
Correction characteristic determining means (S4008) for reading a gradation pattern image formed on the recording paper and determining density correction characteristics of the recording means;
An image forming apparatus having correction means (25) for reflecting density correction characteristics determined by the correction characteristic determination means in image generation by the recording means,
Further, the recording means is controlled so as to continuously generate the gradation pattern on the recording paper a predetermined number of times, and the gradation pattern image read in the last of the plurality of times is determined for density correction characteristics. Control means (S4006, S4007) for controlling the correction characteristic determining means for use in
The control means controls to regenerate the image of the interrupted gradation pattern on the recording paper a predetermined number of times continuously when the automatic gradation correction is resumed after being interrupted (S4014). Forming equipment. The image forming apparatus according to claim 1, wherein the control unit controls to change processing according to an elapsed time from the interruption when the automatic gradation correction is resumed after the interruption. The control means controls to regenerate the image on the recording paper for the remaining number of times of the interrupted gradation pattern when the elapsed time is less than the first predetermined time (YES in S5003). If the second predetermined time is longer than the predetermined time, the automatic gradation correction is controlled from the beginning (YES in S5004). Otherwise, the interrupted gradation pattern is continuously recorded a predetermined number of times. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled to regenerate an image on paper (NO in step S <b> 5004).