JP7149133B2 - Inkjet printer and its system - Google Patents

Description

The present invention relates to inkjet printers.

2. Description of the Related Art Industrial inkjet recording apparatuses are installed in production lines in factories that produce various products such as food and beverages, and print characters and the like on printed objects.

Moreover, Patent Document 1 is known as a background art of a system in which codes are printed on various products and the printed codes are read by an optical reader. In Japanese Patent Application Laid-Open No. 2002-200001, in order to improve the reading stability of barcodes and the like, printing conditions are set based on reading by an optical information reading device instead of visual reading by a user.

Japanese Patent Application No. 2012-148309

The printing quality of industrial inkjet printers is greatly affected by the installation environment and years of operation. Inkjet printers require regular maintenance to maintain high print quality.

Even if the technology described in Japanese Patent Laid-Open No. 2003-100000 makes initial settings using printing conditions that improve reading stability, as described above, the inkjet printer will cause printing defects depending on the installation environment and the number of years it has been in operation.
There are various causes of printing defects, and a system that efficiently performs maintenance according to the causes of printing defects is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inkjet printer and a system for such an inkjet printer that efficiently performs maintenance for printing defects in the inkjet printer.

A preferred example of the present invention includes an ink ejector that forms ink particles from ink, a charging electrode that charges the ink particles, a deflection electrode that changes the flying path of the charged ink particles,
The inkjet printer includes a control unit that specifies a print setting parameter corresponding to a cause of a printing defect based on an inspection result of a dot pattern of a print object, and changes the specified print setting parameter.

Another preferred example of the present invention includes an ink ejector that forms ink particles from ink, a charging electrode that charges the ink particles, a deflection electrode that changes the flying path of the charged ink particles, and a print inspection unit that inspects print; a control unit that identifies print setting parameters corresponding to causes of poor printing based on the inspection results of the print on the print target, and changes the identified print setting parameters; and a display that warns of the need for part replacement.

According to the present invention, maintenance for printing defects can be efficiently performed.

1 is a diagram showing the basic configuration of an inkjet printer according to Embodiment 1. FIG. FIG. 10 is a diagram showing a dot pattern when printed correctly; FIG. 10 is a diagram showing a dot pattern when printing is not performed correctly; FIG. 2 is a diagram showing the usage environment of the inkjet printer according to the first embodiment; 4 is a diagram showing a processing flow in the first embodiment; FIG. 4A and 4B are diagrams for explaining an inspection in the first embodiment; FIG. The figure which shows the processing flow regarding a parameter change. It is a figure explaining the warning display of component replacement. The figure which shows the dot pattern in which the dot was missing. FIG. 4 shows a distorted dot pattern; FIG. 4 is a diagram for explaining inspection of missing dots; FIG. 4 is a diagram for explaining inspection of distorted printing; FIG. 10 is a diagram showing a processing flow of parameter change in the second embodiment; FIG. 11 is a diagram showing a processing flow in the third embodiment; The figure which shows a defect cause list. The figure which shows the estimation formula of a defect cause. FIG. 11 is a diagram showing a processing flow of parameter change in the fourth embodiment;

Examples will be described below with reference to the drawings.

In this embodiment, printed characters are inspected using an image, the excitation voltage is automatically adjusted based on the information on the deviation from the normal printing position, and a warning is issued to replace the ink.

FIG. 1 is a diagram showing the basic configuration of an inkjet printer. Ink pumped from the ink tank 104 by the pump 103 flows into the ink ejector 101 . The ink ejector 101 vibrates according to a sinusoidal voltage generated by an excitation voltage generator 102 to form ink droplets. The ink particles are charged by the charging electrode 105 , change their flight path according to the voltage applied to the deflection electrode 106 , and head toward the printing object 108 . Ink particles that are not voltage-applied and whose flight paths have not changed are collected by the gutter 107 and returned to the ink tank 104 again.

FIG. 4 is a diagram showing an example of an environment in which an inkjet printer is used. A print target 108 is flowing by the belt conveyor 402 . Ink is ejected from a nozzle 404 of an inkjet printer 403 to print. The printing status is displayed on the display device 405 . The printed characters are inspected by the print inspection device 406, and the inspection status is fed back to the inkjet printer 403 as necessary. The display device 405 may be provided in the inkjet printer 403, or may be a display connected to a server or the like connected to the inkjet printer 403 via a network.

FIG. 2 shows the dot pattern when printed correctly. Here, the case of printing "ABCD" is shown as an example. All dots are printed normally and have excellent readability.

FIG. 3 shows a dot pattern that is printed incorrectly. An entire particular row (5th row from top) is shifted downwards from the desired position.

This misalignment is caused by various factors, but is mainly due to deterioration of the ink. The properties of ink change due to factors such as evaporation of water and contamination with impurities. The excitation voltage generated from the excitation voltage generator is optimized according to the properties of the ink, and if the properties change due to the deterioration of the ink, the excitation voltage value becomes non-optimal. This causes misalignment of dots.

Therefore, when the print inspection device 406 detects misalignment, the misalignment information is fed back to the inkjet printer and the excitation voltage is adjusted, thereby eliminating the misalignment without stopping the production line. However, there is a limit to the amount of ink deterioration that can be corrected by adjusting the excitation voltage. Since the timing of ink replacement can be estimated from the misalignment information, this is displayed on the display device to issue an ink replacement warning.

FIG. 5 is a diagram illustrating a processing flow in the first embodiment; The inkjet printer is provided with a control unit having a processor such as a microcomputer, and when the control unit instructs the start of printing, the inkjet printer starts printing (step 501). An inkjet printer prints by ejecting ink particles onto a printing object (step 502).

The print inspection device 406 inspects the characters printed on the print object (step 503). Based on the inspection results from the print inspection device 406, the print inspection device 406 determines whether the inspection has passed (step 504).

If the inspection passes, printing is continued. If it fails, the controller changes the excitation voltage value as an example of print setting parameters (step 505). Further, based on the changed excitation voltage value, the control unit determines whether ink replacement is necessary (step 506).

If replacement of parts such as replacement of ink is required, the controller instructs the display device 405 to display a replacement warning (step 507). Thereafter, the process returns to step 502 to continue printing. On the other hand, if there is no need to replace the display parts, the process returns to step 502 to continue printing.

In this example, the print inspection apparatus 406 inspects and determines whether the inspection is successful or not. Device 406 may perform. In that case, the control unit determines whether the inspection is successful by transmitting the calculated result to the inkjet printer and comparing the calculated deviation with the value of the deviation distance for inspection failure in FIG. 6, which will be described later. Also, the roles may be shared.

The control unit may control the entire inkjet printer, or may be a control unit dedicated to print settings. Also, the controller may be provided in a server separate from the inkjet printer.

FIG. 6 is a diagram for explaining print inspection. In print data 601 acquired by print inspection device 406, normal dot positions 602 and actual dot positions 603 are compared, and dot deviation 604 is calculated from the distance. This dot displacement is averaged for each row, and the value is compared with the displacement determination distance 605 for inspection. If the deviation is larger than the inspection failure line 606, the inspection is rejected, and the deviation information is fed back to the inkjet printer. This inspection failure line is set more severely than the print obfuscated line where printed characters cannot be read, and printing can be continued even in the inspection failure state. If the misalignment exceeds the printing obfuscation line, the product is removed from the production line as a printing failure.

FIG. 7 shows a detailed processing flow of the process (step 505) of specifying a parameter corresponding to the cause of printing failure, ie, deterioration of ink, and changing the parameter in FIG. First, based on the feedback information from the print inspection device 406, the control unit determines whether parameter change is necessary (step 701). If parameter change is required (Yes in step 701), it is determined whether to abort the parameter change (step 712).

If the parameter change loop has been circulated a predetermined number of times or more, it is determined in step 712 that correction by parameter change is impossible (Yes in step 712). If not aborted (No in step 712), the control unit checks whether there is a previous change record that records the parameter and the inspection result for that parameter (step 702).

If there is no previous change record (No in step 702), the control unit determines whether to increase or decrease the excitation voltage depending on whether the direction of misalignment is upward (step 703). According to the determination, control is performed to raise the excitation voltage (step 704) or to lower the excitation voltage (step 705).

The controller then records the direction of voltage up or down and the current deviation (step 706). If there is a change record (Yes in step 702), the test result is obtained from the print inspection device 406 with the newly changed parameters, and the control unit indicates the extent of the print defect compared to the previous time. A check is made to see if the deviation has decreased (step 707).

If so, the voltage change direction is correct, so the parameter change amount is increased (step 708). If so, the direction of change is wrong, so the control unit reverses the direction of parameter change and obtains the inspection result from print inspection device 406 (step 709).

The controller then records the changes again (step 710). If parameter change is not necessary (No in step 701), the control unit deletes the change record (step 711) and completes the change.

FIG. 8 is a diagram for explaining a warning display for part replacement. 801 indicates a settable excitation voltage range. 802 is the initial value of the excitation voltage. At the start of use, normal printing is possible with this excitation voltage. When the ink deteriorates with the lapse of time, the set value of the excitation voltage is changed by changing the parameters described above.

If the set value of the excitation voltage is within the allowable excitation voltage range 803, it is determined that the parts need not be replaced, and nothing is done. When the set value of the excitation voltage is included in the replacement warning range 804, it is determined that replacement is necessary, and a warning to replace the part is displayed on the display device.

According to the first embodiment, it is possible to realize an ink jet printer which inspects printed characters by image, automatically adjusts the excitation voltage based on the information of deviation from the normal printing position, and issues an ink replacement warning.

This embodiment shows an example in which not only the excitation voltage but also other parameters are changed in the first embodiment. Descriptions of the same contents as in the first embodiment are omitted.

FIG. 9 is a diagram showing a dot pattern in which some dots are missing from a normal character. FIG. 10 is a diagram showing a dot pattern in which a plurality of irregular dots are misplaced relative to a normal character, and the entire character is distorted. These missing dots and character distortion may also be caused by ink degradation. For these printing defects, it is possible to issue a warning while adjusting the parameters by conducting an inspection.

The overall processing flow of the second embodiment is similar to that of the first embodiment. FIG. 11 is a diagram for explaining inspection of missing dots. 1101 is a character with missing dots. This character is compared with a normal character to determine the number of omissions contained in the character. In this figure, the missing number is one. Continue this test to determine the average number of omissions per character. This is determined by the average missing number 1104 . If the average missing number exceeds the inspection rejection number 1102, the inspection is rejected. It should be noted that the number of test failures is set to be stricter than the print obfuscation number 1103 at which characters become illegible.

FIG. 12 is a diagram for explaining the inspection when characters are distorted. 1201 is a distorted character. For each dot, a distortion distance 1204, which is the difference between the normal dot position 1202 and the actual dot position 1203, is calculated. The average of this distortion distance per character is calculated and determined by the average distortion distance 1205 . If the average distortion distance exceeds the inspection failure 1206, the print inspection device 406 determines that the inspection has failed. It should be noted that the inspection rejection is set more severely than the print obfuscation 1207 .

The missing dot inspection, the character distortion inspection, and the line displacement inspection of the first embodiment are carried out in parallel at the same time. If any one of the inspections fails, the information is fed back to the control section of the inkjet printer.

In Example 1, the excitation voltage was used as the parameter to be changed. However, other parameters need to be changed to deal with various print defects. These are, for example, excitation frequency and ink temperature. By changing a plurality of parameters, it is possible to correct printing defects with higher accuracy.

FIG. 13 shows a processing flow of parameter change in the second embodiment. When there is feedback from the print inspection device 406 that the print inspection has failed, the control unit determines that the print setting parameters need to be changed (step 1301). First, the control unit changes parameter 1 (eg, excitation voltage) (step 1302).

Next, after completing the processing of parameter 1, the control unit changes parameter 2 (excitation frequency, for example) (step 1303).

Next, after the parameter 2 is processed, the control unit changes the parameter 3 (for example, ink temperature) (step 1304). The contents of each parameter change step 1302 to 1304 are the same as the processing flow of FIG. 7 regarding parameter change.

According to the second embodiment, it is possible to realize an inkjet printer that changes not only the excitation voltage but also other parameters such as adjusting the ink temperature.

The present embodiment is an example in which, in addition to the ink replacement warning in the first embodiment, warnings about other printing defects are issued.

In Example 1, the cause of printing defects was found to be deterioration of the ink. However, in practice, printing defects may occur due to other factors. Contamination of nozzles by ink is considered to be a factor caused by passage of time in the same manner as ink deterioration. In addition to changes in members due to the passage of time, changes in the temperature and humidity of the operating environment and poor initial settings are also conceivable. Therefore, the cause of the printing defect is estimated by the control unit executing a defect cause estimation step for estimating the cause of the printing defect.

FIG. 14 shows the processing flow in the third embodiment. Steps 501, 502, 503, 504, 505, and 507 are the same as in FIG. 5, so the description is omitted. If the test fails in step 504, the control unit estimates the cause of the defect (step 1405). The control unit classifies the estimated cause of failure into component failure (ink deterioration, etc.) (step 1408), environmental factors (room temperature rise, etc.) (step 1407), and setting failure (initial setting error) (step 1406). do. Regardless of the cause, the control unit identifies a parameter corresponding to the presumed cause and changes the parameter (step 505). Then, if it is an environmental factor or a part defect, a warning about the printing defect is displayed (step 507).

Defect cause estimation is performed based on the defect cause list. FIG. 15 is a diagram showing a defect cause list. The defect cause list holds correspondence relationships between deviation distances, missing numbers, and distortion distances, which are values indicating dot pattern defects, presumed causes, and print setting parameters to be changed. The cause can be estimated based on the deviation distance, the number of omissions, the distortion distance, and the defect cause list fed back from the print inspection device 406 . Furthermore, it is known which parameters should be changed for the cause. This failure cause list is set in the inkjet printer in advance.

FIG. 16 is a diagram showing an estimation formula for the cause of failure. Xn of the defect cause estimation formula 1601 in FIG. 16 is the likelihood of the cause, and the smaller Xn is, the higher the possibility of the cause. Calculate Xn for all n and take the smallest one as the probable cause.

Here, A, B, and C are values fed back from the inspection device. An, Bn, and Cn are values representing the deviation distance, the number of missing dots, and the distortion distance, which are values indicating the defect of the dot pattern, respectively. Those values are values described in advance in the cause estimation list. DA, DB, and DC are weights of respective terms in a predetermined defect cause estimation formula. Further, accuracy can be improved by using not only feedback from the inspection device but also information from a measuring device such as a thermometer as information used for cause estimation.

According to the third embodiment, it is possible to realize an inkjet printer that changes parameter settings for various factors of failure and displays warnings.

In this embodiment, an example of automatically updating the defect cause estimating unit in the third embodiment will be shown.
In the third embodiment, the parameters for changing the defect cause list used by the defect cause estimator are given in advance. However, the parameters that should be changed may depend on the actual environment.

Therefore, a mechanism is introduced to reflect the effective changes in the list by changing the parameters.

FIG. 17 is a diagram illustrating a processing flow of parameter change in the fourth embodiment.
As in FIG. 13, when there is feedback from the print inspection device 406 that the print inspection has failed, the control unit determines that it is necessary to change the print setting parameters (step 1301). First, the control unit changes parameter 1 (step 1302). A parameter 1 is a parameter that should be changed by the defect cause estimator. For example, this parameter is the excitation voltage. Then, print inspection device 406 determines whether or not the inspection has been passed (step 1703). If this parameter is updated and the inspection is passed (Yes in step 1703), nothing is done in the failure cause list and the process returns to printing. If it fails (No in step 1703), another parameter 2, for example, the ink temperature parameter is changed (step 1303). If the result is a pass (step 1705 Yes), the parameter to be changed in the failure cause list is updated to the ink temperature (step 1707). Such steps are repeated for another parameter 3 .

According to the fourth embodiment, it is possible to realize an inkjet printer that displays a warning while automatically updating the defect cause list.

101 ink ejector 102 excitation voltage generator 105 charging electrode 106 deflection electrode 403 inkjet printer 405 display device 406 print inspection device

Claims (13)

an ink ejector that forms ink droplets from the ink;
a charging electrode that charges the ink particles;
a deflection electrode that changes the flying path of the charged ink particles;
If the inspection result of the dot pattern of the printed object is unsatisfactory,
Estimate the cause of the printing defect from the defect cause estimation formula based on the defect cause list holding the correspondence relationship between the value indicating the dot pattern defect, the estimated cause, and the print setting parameter to be changed, and the inspection result. and a control unit that changes the print setting parameter corresponding to the estimated cause of the print failure . The inkjet printer of claim 1, wherein
The cause of the printing failure is the deterioration of the ink,
said ink ejector forming said ink droplets by means of an excitation voltage generator;
The print setting parameter is the voltage of the excitation voltage generator,
The control unit
An inkjet printer, wherein the voltage of the excitation voltage generator is changed. The inkjet printer according to claim 2, wherein
The control unit
An ink jet printer as claimed in claim 1, wherein it is determined whether or not a part needs to be replaced based on the voltage change amount. The inkjet printer according to claim 2, wherein
The control unit
recording the print setting parameters;
An ink jet printer characterized by judging the presence or absence of the recorded print setting parameters. The inkjet printer according to claim 4, wherein
The control unit
If there are the recorded print setting parameters,
Newly set the print setting parameters,
An inkjet printer, wherein a change in the print setting parameter is specified based on a comparison of the extent of the printing defect in the recorded print setting parameter. The inkjet printer according to claim 4, wherein
The control unit
If there is no recorded print setting parameter,
An inkjet printer, wherein the voltage of the excitation voltage generator is changed based on the inspection result. The inkjet printer according to claim 3, wherein
The control unit
If it is determined that replacement of the above parts is necessary,
1. An ink jet printer, characterized in that a display section displays a warning that the component should be replaced. The inkjet printer of claim 1, wherein
there are a plurality of the print setting parameters;
The control unit
An inkjet printer, wherein a plurality of said print setting parameters are changed. The inkjet printer of claim 1 , wherein
The control unit
By changing the estimated print setting parameter, if the inspection result passes,
An inkjet printer, wherein the print setting parameters of the failure cause list are updated. an ink ejector that forms ink droplets from the ink;
a charging electrode that charges the ink particles;
a deflection electrode that changes the flying path of the charged ink particles;
a print inspection unit that inspects print on a print target;
If the inspection result of the printing on the printing object is unsatisfactory ,
The cause of the printing defect is estimated from the defect cause estimating formula based on the defect cause list holding the correspondence relationship between the value indicating the dot pattern defect, the estimated cause, and the print setting parameter to be changed, and the inspection result. , a control unit that changes the print setting parameter corresponding to the estimated cause of the print defect ;
a display that warns about printing defects;
An inkjet printer system comprising: 11. The inkjet printer system of claim 10 , wherein
The print inspection unit is
An ink jet printer system, characterized in that misalignment of a dot pattern on the printing object is detected. 11. The inkjet printer system of claim 10 , wherein
The print inspection unit is
An inkjet printer system, wherein the number of missing dots on the printing object is detected. 11. The inkjet printer system of claim 10 , wherein
The print inspection unit is
An inkjet printer system, wherein distortion of a dot pattern on the printing object is detected.

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