JP2006231728A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer that can prevent the delay of a date of delivery due to interruption of a printing work by continuing the printing in the case where a prescribed level of printing quality is maintained even when the printing quality is degraded during the printing operation. <P>SOLUTION: When a difference obtained by comparing image data with data taken by reading image data printed on a recording medium by using a CCD sensor or the like exceeds a predetermined threshold, the printing is temporarily stopped. When the threshold is in a regulation, the threshold is changed and the printing is restarted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet printer.

  In recent years, with the widespread use of ink jet printers, methods for performing a large amount of printing with ink jet printers have been proposed. Further, when printing with an ink jet printer, since there are a wide variety of recording media such as paper and cloth, it is becoming increasingly popular. However, in the case of continuous operation for a long time, even if the head is maintained at regular intervals, the nozzles of the recording head are clogged, the ink ejection is bent, etc. There was a problem that it would deteriorate.

In order to prevent the occurrence of these problems, a recording material for generating a discharge signal for driving a recording head for recording an image by an ink jet method is generated based on the input recording image data, and the recording head is driven to generate a recording material. In parallel, while recording images continuously, the output image recorded on the recording material is read by the CCD sensor, and the output image data obtained by the reading is compared with the corresponding recording image data, By comparing the output image data of the output image with each other, the occurrence of an event such as clogging of the ejection head of the recording head or a decrease in the ejection amount of the ink droplet is monitored, and the occurrence of the event is eliminated. Process. (For example, Patent Document 1)
JP 2002-160354 A

  However, according to the above-mentioned background art, since processing is performed for restoration, the recording process is temporarily stopped, the head is repaired or replaced, and printing for recovery confirmation is performed. Therefore, the paper in the middle of printing at the time of the trouble and the printing paper for confirmation are wasted and the conventional printing work is delayed, resulting in an increase in printing cost and a delay in delivery time.

  In view of this, the present invention reduces the delivery time due to the interruption of the printing work by changing the quality standard and continuing the printing when a certain level of the printing image quality is maintained even if the printing quality is defective during the printing operation. An object of the present invention is to provide an inkjet printer that prevents the above.

  The object of the present invention can be achieved by the following constitution.

The invention according to claim 1
In an inkjet printer that records an image on a recording medium by discharging droplets from a recording head based on input image information,
Reading means for photoelectrically reading an image of a recorded medium;
Image storage means for storing an image read by the reading means;
Comparing means for comparing the image information with the image stored in the image storage means to generate comparison information;
Determining means for determining whether the comparison information exceeds a threshold;
Warning generating means for issuing a warning of threshold change when the comparison information exceeds a threshold;
Operating means for instructing the change of the threshold;
When the warning is issued, the ink-jet printer includes control means for changing to a new threshold value based on the instruction for changing the threshold value and the comparison information.

The invention according to claim 2
2. The ink jet printer according to claim 1, wherein the threshold value is a value based on a type of recording medium and a ratio of pixels to be effectively printed with respect to all pixels of the image data.

The invention according to claim 3
3. The ink jet printer according to claim 1, wherein when the warning generation unit issues a warning, the control unit performs a process of temporarily stopping the recording of the image information on the recording medium.

The invention according to claim 4
4. The comparison information according to claim 1, wherein the comparison information is a value obtained by dividing a total of printed pixels stored in the image storage means by a total of pixels printed effectively in the image information. It is an ink jet printer given in any 1 paragraph.

  According to the first aspect of the present invention, when the quality of the printed material exceeds the threshold value, the printed material can be continuously produced by changing to a new threshold value based on the comparison information.

  According to the second aspect of the present invention, since the threshold is based on the type of recording medium and the ratio of pixels that are effectively printed with respect to all the pixels of the image data (hereinafter referred to as the printing rate), it is visually and sensitively. It is equivalent to quality, and it becomes possible to produce printed matter that maintains sensitive quality.

  According to the third aspect of the present invention, when the warning generating means issues a warning, the recording of the image information on the recording medium is temporarily stopped, so that it is possible to prevent the production of printed matter of nonstandard quality.

  According to the invention described in claim 4, since the comparison information is generated based on the number of pixels of the image data, it is unified, and since the degree of image quality failure is immediately determined, it is useful for failure cause analysis.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, FIG. 1 shows a mechanical configuration of an ink jet printer centering on a carriage portion according to the present embodiment.

  The ink jet printer 10 includes a carriage unit 2, a support bar 3, a drive belt 4, a main scanning motor 41, rollers 6 a and 6 b, and a recording medium 1. The recording medium 1 is made of a recording paper or the like on which image information is recorded, and is moved in the sub-scanning direction that is the transport direction. The support bar 3 is a metal bar that faces the main scanning direction orthogonal to the sub-scanning direction, and is arranged so that the carriage unit 2 can move in the main scanning direction. The carriage unit 2 is fixed to the drive belt 4, and the drive belt 4 wound around the rollers 6 a and 6 b is moved by driving of the main scanning motor 41. As a result, the carriage unit 2 moves in the main scanning direction on the support bar 3 and prints on the recording medium 1.

  The carriage unit 2 is detachably mounted with cartridges 1K, 1C, 1M, and 1Y containing black K, cyan C, magenta M, and yellow Y inks. A head for each of 1K, 1C, 1M, and 1Y (not shown) is present at the lower end of the carriage unit 2, and recording that exists at the lower end of the carriage unit 2 from nozzles that are a plurality of ink ejection ports of each head. Ink is ejected onto the medium 1.

  FIGS. 2A and 2B are enlarged views of the lower end portion of the head 21d connected to the cartridges 1K, 1C, 1M, and 1Y and the cartridge 1Y mounted on the carriage unit 2. FIG. FIG. 2A shows the head 21d existing at the lower end of the cartridge 1Y mounted on the carriage unit 2. FIG. Here, the head 21d has a plurality of nozzles arranged in a line in the sub-scanning direction as shown in FIG. From this nozzle, ink in the cartridge 1Y shown in FIG. 2A is simultaneously ejected, and a row of ink droplets arranged in the sub-scanning direction is recorded on the recording medium 1. The cartridges 1K, 1C, 1M, and the heads 21a to 21c corresponding to these cartridges (not shown) have the same structure and are juxtaposed in the main scanning direction of the carriage unit 2.

  Further, the heads 21a to 21d and the cartridges 1K to 1Y of the carriage unit 2 can be individually replaced, and are replaced when the heads 21a to 21d are deteriorated or the ink in the cartridges 1K to Y is exhausted. The 1 and 2, it is assumed that the cartridges 1K to Y including the heads 21a to 21d and the ink are present in the carriage unit 2. However, the cartridges 1K to Y are fixedly disposed outside the carriage unit 2, and the head 21a is formed by a tube or the like. It is also possible to supply ink to .about.d.

  FIG. 3 is a block diagram showing an electrical configuration of the inkjet printer 10.

  The inkjet printer 10 includes an interface controller 61, an image memory 64, a transfer unit 71, a carriage unit 2, a control unit 80, a main scanning motor 41, a sub-scanning motor 42, an operation panel 30 as an operation unit, a cleaning unit 66, and a calculation unit 401. , Calculating means 402, reading means 81, and image storage means 82. The inkjet printer 10 is connected to the host computer 50 and acquires image information to be recorded.

  The interface controller 61 serves as input means for capturing image information from the host computer 50 connected via a communication line.

The image memory 64 temporarily stores image information acquired via the interface controller 61. This image information is a part of the original image information of the host computer 50 and includes the minimum necessary image information for printing by the carriage unit 2 described later. The image information is formed for each color of black, cyan, magenta, and yellow.

  The carriage unit 2 prints image information in the image memory 64 on the recording medium 1. Here, the carriage unit 2 includes heads 21a to 21d, head drive control circuits 23a to 23d, a drive circuit 22, and an encoder sensor 26. The heads 21a to 21d are respectively a black ink (K) discharge head 21a, a cyan ink (C) discharge head 21b, a magenta ink (M) discharge head 21c, and a yellow ink (Y) discharge head. 21d and juxtaposed in the main scanning direction as shown in FIG. Each head has, for example, 512 nozzles that eject ink, which are arranged in a line in the sub-scanning direction, as shown in FIG. 2B.

  The heads 21a to 21d eject the inks of the cartridges 1K, 1C, 1M, and 1Y onto the recording medium 1 as ink droplets. As the heads 21a to 21d, for example, share mode type piezo heads are used.

  The head drive control circuits 23a to 23d control ejection timing of ink droplets for each of the heads a to d based on image information from the image memory 64. In the head drive control circuits 23a to 23d, a driver for driving the piezo head exists for each channel, and drives the piezo head based on the drive waveform from the drive circuit 22.

  The encoder sensor 26 is present on the carriage unit 2 and reads, for example, a black mark engraved with a predetermined interval in the main scanning direction of the support bar 3. Thereby, the position of the carriage unit 2 in the main scanning direction is accurately grasped, and the ink ejection timing is made accurate.

  The transfer unit 71 transfers partial image information recorded by one ejection from a plurality of nozzles of each head from the image memory 64 to the head drive control circuits 23a to 23d. The transfer means 71 includes a timing generation circuit and a memory control circuit. The timing generation circuit obtains an accurate position of the carriage unit 2 from the outputs of the home position sensor and encoder sensor 26 (not shown), and the memory control circuit uses this position information to address the partial image information required for each head. Ask for. Then, the memory control circuit reads out from the image memory 64 and transfers it to the head drive control circuits 23a to 23d using the address of the partial image information.

  The main scanning motor 41 is a motor that moves the carriage unit 2 in the main scanning direction shown in FIG. The sub-scanning motor 42 is a motor that transports the recording medium 1 in the sub-scanning direction.

  The control unit 80 includes a CPU 60 and a memory 65, and controls the transfer unit 71 together with the control of the main scanning motor 41 and the sub scanning motor 42, and controls the ejection of ink onto the recording medium 1. Also, integrated values from calculation means 401 and 402 described later are compared and determined, and a warning is generated based on the determination result. Furthermore, the calculation at the time of changing the threshold is performed.

  The memory 65 is composed of a non-volatile memory, and stores a program that is an operation sequence of the CPU 60, a threshold value according to the present invention, and other printing conditions input from the operation panel.

  The operation panel 30 serves as an operation means, and includes an LCD, a keyboard, and the like, and inputs or displays printing conditions. Further, an instruction to change the threshold value according to the present invention is given.

  The cleaning unit 66 cleans the heads 21a to 21d. In this cleaning, for example, by adhering to the nozzles of the heads 21a to 21d at the home position or wiping them with a material such as rubber or a plate, the deposits that disturb the ejection of ink from the nozzles are removed. .

  The reading unit 81 reads an image recorded on the recording medium for each color of C, M, Y, K using a sensor such as a CCD and stores the image in the image storage unit 82.

  The calculation means 401 uses the image stored in the image information stored in the image memory 64 to effectively print the binary information of each color of C, M, Y, and K of the image data for each of the heads 21a to 21d. Accumulate the number of pixels. Similarly, the calculation unit 402 integrates the number of printed pixels of C, M, Y, and K colors of the image data read by the reading unit 81 and stored in the image storage unit 82.

  Next, an example of the operation of the system according to the present invention will be described with reference to FIGS.

  FIG. 4 is a functional block diagram of the control unit according to the present invention.

  The control unit 80 includes comparison means 85, determination means 86, memory 65, warning means 83, and control means 87.

(Fidelity)
Fidelity is a parameter that represents the ratio of reproducibility from original image data to image data printed on a recording medium.

The comparison unit 85 calculates the fidelity (comparison information) from the binary information of the image data input from the calculation units 401 and 402.
As an example of the calculation method of the fidelity P, it is expressed by Expression (1).

Formula (1)
P (%) = G / Fx100
G: Total number of pixels printed in the image of the image storage means 82 F: Total number of pixels printed effectively in the image in the image memory 64 (fidelity correction value)
The fidelity correction value refers to the amount of data stored in the image storage means 82 that is an error value of the reading means 81 or the amount of data due to the background of the recording medium superimposed on the actual value. In order to obtain accurate fidelity, it is necessary to subtract this correction value from the calculated fidelity.

  Data is read by the reading means 81 and stored in the image storage means 82. Next, a state where all the image data is printed is stored in the image memory 64. The numbers of print pixels in the image storage means 81 and the image memory 64 are respectively integrated by the calculation means 401 and 402, and then calculated by the comparison means 85 to calculate the fidelity correction value Pi. The calculation of the fidelity correction value Pi is performed using Equation (2).

Formula (2)
Pi (%) = G / Fix100
G: Total number of pixels printed in the image of the image storage means 82 Fi: Total number of pixels of the image in the image memory 64 (meaning the size of the image data)
Pi is the ratio between the total number of dots and the image size when the reading unit 81 reads a recording medium on which an image without data is printed.
The calculated result is stored in the location indicated by the initialization value 8421 and the recording medium 8410 in the threshold value table 84. For example, if the recording medium is glossy paper 8414, P ₀₃ 8424 is stored.

  Here, the threshold value table 84 will be described with reference to FIG.

  The vertical axis is a table having the type of recording medium and the horizontal axis is the printing rate, and threshold values are stored in the cells indicated by these. The threshold here refers to a boundary value between pass and fail of a value (fidelity) indicating reproducibility from image data to an image in which the image data is printed on a recording medium. The threshold value is displayed in% like fidelity.

  As the type of the recording medium, towels, moquettes, silk, and the like are used for cloth, and glossy paper, high-quality paper, plain paper, and the like that can be printed by an inkjet printer are selected for paper.

  The printing rate is displayed in%, and 0.0 to 1.0 indicates that the number of pixels to be printed is 0.0 to 1.0% with respect to the total number of pixels. That is, it means that the entire image is hardly printed. Similarly, in 99.1 to 100.0, the entire image is almost printed.

The threshold indicated by A _xy indicates the class of the printing rate and x indicates the type of the recording medium. For example, if it is A ₂₂ , it is image data with a printing rate of 1.1 to 2.0%. To say.

Returning to FIG.
When the determination unit 86 determines that the threshold value is greater than the fidelity (when the comparison information exceeds the threshold value), the control unit stops the printing operation, and the warning generation unit 83 issues a warning to the operation panel 30. Notify me. Upon receiving the notification, the operation panel 30 displays a warning on a display (not shown), for example, an LCD. Further, a buzzer may be added to the operation panel 30 to generate a warning sound and notify the operator. Further, a warning lamp may be added to light the lamp.

  The operator who has recognized the warning notifies the control means 87 whether or not to continue printing by key input on the operation panel 30.

(Threshold change 1)
In the case where it is notified that the printing is continued, the control unit 87 changes the threshold value to the fidelity P and rewrites the threshold value table 84.

(Threshold change 2)
If it is notified that the printing is to be stopped, the printing is stopped after the threshold value is changed and the threshold value table 84 is rewritten.
As an example of the calculation method of the threshold value to be changed, it is expressed by Expression (3).

Formula (3)
Ab = Aa− (Aa−P) / γ
Ab: New threshold value Aa: Current threshold value P: Fidelity γ: Constant constant γ is a number of 1 or more and is set at the time of shipment from the factory. In the above equation (2), the new threshold value Ab is determined to be an intermediate value between the current threshold value Aa and the fidelity P.

(Threshold change 3)
On the other hand, when the determination unit 86 determines that the threshold value is smaller than the fidelity, the threshold value is changed and the threshold value table 84 is rewritten, and then printing is continued.
As an example of the calculation method to be changed, it is expressed by Expression (4).

Formula (4)
Ab = Aa + (P−Aa) / γ
FIG. 6 is a flowchart showing the threshold value changing process in the image forming operation.

  This flowchart starts by recognizing that printing of one sheet is completed.

In step S1, the above-described initialization fidelity P _0y corresponding to the recording medium is read from the threshold value table 84 and set to the fidelity correction value Pi.

  In step S2, a value obtained by subtracting the fidelity correction value from the fidelity P is set as the fidelity P. The fidelity P is a value obtained by correcting an error of the reading device and a value due to the background of the recording medium.

In step S3, the threshold value A _xy stored in the threshold value table 84 is read from the printing rate and the recording medium. For example, when the printing rate is 1.1 to 2.0% and the recording medium is silk, A ₂₂ is read and set to Aa.

  In step S4, the fidelity P is compared with the threshold value Aa. If Aa is larger than P, that is, if the printed image is worse than the set threshold value (step S4: YES), printing is performed to step S5. If the image is better than the set threshold value (step S4: NO), the process proceeds to step S12.

  In step S5, the printing operation is temporarily stopped and a warning is displayed on the operation panel 30. The operator who has recognized the warning determines whether or not to continue printing by key input on the operation panel 30 and notifies the control means 87 of it. If printing is to be stopped (step S5: YES), the process proceeds to step S6. If printing is to be continued (step S5: NO), the process proceeds to step S9.

  In step S6, calculation is performed according to equation (3).

  In step S7, Ab as the calculation result is stored in Axy designated by the recording medium and the printing rate in the threshold value table 84.

  In step S8, the print command is terminated.

  In step S9, the fidelity P is set to Ab.

  In step S10, Ab is stored in Axy designated by the recording medium and the printing rate in the threshold value table 84.

  In step S11, the printing operation is resumed and continued.

  In step S12, calculation is performed according to equation (4). Next, the process proceeds to step S10.

  In addition, the detailed configuration and detailed operation of each component constituting the ink jet printer according to the present invention can be changed as appropriate without departing from the spirit of the present invention.

It is a figure which shows the mechanical structure of the inkjet printer of this invention. FIG. 4 is an enlarged view of a cartridge mounted on the carriage of the present invention and a lower end portion of a head mounted on the cartridge. 1 is a block diagram illustrating an electrical configuration of an inkjet printer according to the present invention. It is a functional block diagram of the control part of this invention. It is a figure which shows the threshold value table of this invention. 6 is a flowchart illustrating threshold value changing processing in the image forming operation of the present invention.

Explanation of symbols

1K to Y Cartridge 1 Recording medium 2 Carriage section 3 Support rod 4 Driving belt 6a to b Roller 10 Inkjet printer 21a to d Head 22 Driving circuit 23a to d Head driving control circuit 26 Encoder sensor 30 Operation panel 41 Main scanning motor 42 Sub scanning Motor 50 Host computer 61 Interface controller 64 Image memory 65 Memory 66 Cleaning means 71 Transfer means 80 Control part 81 Reading means 82 Image storage means 401 Calculation means 402 Calculation means

Claims (4)

In an inkjet printer that records an image on a recording medium by discharging droplets from a recording head based on input image information,
Reading means for photoelectrically reading an image of a recorded medium;
Image storage means for storing an image read by the reading means;
Comparing means for comparing the image information with the image stored in the image storage means to generate comparison information;
Determining means for determining whether the comparison information exceeds a threshold;
Warning generating means for issuing a warning of threshold change when the comparison information exceeds a threshold;
Operating means for instructing the change of the threshold;
An inkjet printer comprising: control means for changing to a new threshold value based on the instruction for changing the threshold value and the comparison information when the warning is issued. 2. The ink jet printer according to claim 1, wherein the threshold value is a value based on a type of recording medium and a ratio of pixels to be effectively printed with respect to all pixels of the image data. 3. The ink jet printer according to claim 1, wherein when the warning generation unit issues a warning, the control unit performs a process of temporarily stopping recording of image information on a recording medium. 4. The comparison information according to claim 1, wherein the comparison information is a value obtained by dividing a total of printed pixels stored in the image storage means by a total of pixels printed effectively in the image information. The inkjet printer according to any one of the above.

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