JPS63221050A - How to detect jetting errors in inkjet printers - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an ejection error detection method for an inkjet printer, and particularly to an ejection error detection method for detecting whether or not ink particles ejected from an ejection nozzle of a recording head are normally ejected in an on-demand type inkjet printer. Regarding.

[Conventional technology]

On-demand inkjet printers eject ink particles from nozzles by changing the volume of a pressure chamber each time an electric pulse is applied to a piezoelectric transducer of a recording head in response to an electric signal for recording. In this type of on-demand inkjet printer,
Compared to so-called continuous inkjet printers, which eject ink particles continuously from a nozzle,
Ink droplet ejection errors are likely to occur. This is because the ejection nozzle of the print head is close to the recording paper, so dust such as paper powder may adhere to the ejection nozzle surface, air bubbles may enter the inside of the print head, or the ink inside the ejection nozzle may dry. These are abnormal accidents such as misdirection of injection, failure to inject, and incomplete injection that occur due to factors such as solidification due to changes over time. Missing dots on the recording paper due to these ejection errors degrade print quality or cause information to disappear, so it is necessary to promptly detect this and take recovery measures.

[Problems to be Solved by the Invention 1] However, the method for detecting the above-mentioned injection errors is currently performed visually, and everything from detection to recovery measures is performed manually. As a result, there are problems in that monitoring work is cumbersome and the discovery of injection errors is not accurate or quick.Furthermore, there are also problems in the troublesome accident recovery operation and the time required for corrective action.To solve these problems, Various injection error detection devices have been considered so far. SUMMARY OF THE INVENTION An object of the present invention is to provide an ejection error detection device for an inkjet printer that solves such problems and easily detects ejection errors. [Means for Solving the Problems] The present invention employs a method of measuring the resistance of ejected ink as a method for detecting ejection errors. In this method, ink particles containing an electrolyte are ejected to a pair of ejection error detection electrodes placed opposite the ejection nozzle surface of the recording head, and depending on whether or not a current flows between the electrode pair, the ink particles This system detects whether or not the fuel is being injected normally, thereby making it possible to reliably detect injection errors and eliminating the need for human monitoring. [Example] Fig. 4 shows the detection principle of the present invention. When ink particles 12 having an electrolyte as a component are jetted into the detection gap 11 between the common electrode 4 and the individual electrodes 10, a gap of 1 to 100 μm is created between the common electrode 4 and the individual electrodes 10 due to the separation of the electrolyte.
By applying a square wave (5 to 24 V) of s, a current flows between the two electrodes and the detection resistor 13 in the detection circuit receives vo.
A voltage is generated. When the generated voltage is Ov, it is determined that there is an injection error, and when it is vOv, it is determined that the injection is normal, by a circuit not shown. The electrolytes mentioned above include dyes, preservatives, chelating agents and pHt
)l preparations, etc. The common electrode 4 and the individual electrodes 10 can be formed of a metal thin film of nickel, chromium, gold, or the like formed by photolithography or printing on an insulator such as glass (not shown). FIG. 5 shows an electrode pattern for detecting incomplete injection according to the present invention. Incomplete ejection is not a complete inability to eject, but is a phenomenon in which ejection becomes impossible or ink particles become smaller when several ink droplets are ejected in succession. The detection pattern has two detection gaps,
A plurality of ink particles are continuously ejected between the detection patterns, and incomplete ejection is determined depending on whether the first and last ink particles 17 and 18 adhere to the two detection gaps 11 and establish electrical continuity. To detect. Common electrode 4 and individual electrode 10
An auxiliary electrode 16 is provided between the two electrodes to prevent the resistance value between the two electrodes from becoming too large. FIG. 1 is a configuration diagram of an electrode pattern showing an embodiment of the present invention. The recording head is mounted on a carriage controlled by a space feed position detector (not shown) and is scanned from left to right across the electrode pattern in the figure. By scanning the carriage, an arbitrary one of the plurality of ejection nozzles of the recording head (not shown) reaches a point 2 to 20 dots away from the left and right position detection gap 6 (time 5).
Then, ink jetting is started from any of the jetting nozzles mentioned above. When the carriage moves to the right and the dot reaches the left and right position detection gap 6, the common electrode 4 and the left and right position detection electrode 1
A current flows between them, and a potential is generated in a detection circuit (not shown) connected to the wiring group, indicating that conduction has been established. The absolute position of the position detector at this time is stored as the left and right positions in a control circuit (not shown). Next, the carriage is further scanned to the right and reaches the upper and lower position detection gap group 2. Here, based on the absolute horizontal position obtained by the horizontal position detection, ink particles are ejected into the vertical position detection gap group 2 that is vertically shifted by one integer of the interval between the ejection nozzles of the recording head. go. When the ink particles reach the vertical position detection gap 7 and electrical continuity is established, the absolute vertical position is stored in a control circuit (not shown) as the horizontal position of the carriage in the same manner as the horizontal position detection. Further, the carriage is scanned to the right and reaches the injection error detection gap group 3. The ejection error detection gap group 3 is shifted upward by one integer of the interval between the ejection nozzles of the recording head as it goes to the right. By a control circuit (not shown), toward the injection error detection gap group 3,
Based on the previously stored horizontal and vertical positions, a plurality of ink droplets 8 are continuously ejected at the maximum usable frequency of the recording head from the ejection nozzle whose position matches the ejection error detection gap. Ejection error detection is determined by whether or not the first ink droplet and the last ink droplet of the successively ejected ink droplets adhere to each of two detection gaps to create electrical continuity between the electrode pairs. Detected by. Furthermore, if there is an error in the ejection direction, no ink particles will adhere to the detection gap and electrical continuity will not be obtained, so that an ejection error will be detected. In horizontal position detection or vertical position detection, if continuity is not obtained even after the number of ejected ink particles exceeds a certain number, it is determined that the ejection nozzle for position detection has made an ejection error at that point. Furthermore, it is determined that an injection error has occurred at the time when continuity is no longer obtained in the injection error detection gap. In this way, if an ejection error is detected midway through, the recording head return operation is automatically performed at that point. FIG. 2 shows another embodiment of the present invention, in which the recording head is mounted on a carriage controlled by a space feed position detector (not shown) and is scanned from left to right across the electrode pattern in the figure. From the point at which any one of the plurality of ejection nozzles of the recording head (not shown) reaches a point 2 to 20 dots away from the left/right position detection gap 6 due to the scanning of the carriage, ink is discharged from the ejection nozzle. Start injection. When the carriage moves to the right and the dot reaches the left-right position detection gap 6, a current flows between the common electrode 4 and the left-right position detection electrode 1, and a potential is generated in a detection circuit (not shown) connected to the wiring group, establishing continuity. It turns out that it was done. The absolute position of the position detector at this time is stored as the left and right positions in a control circuit (not shown). next,
The carriage is further scanned to the right and reaches an injection error detection gap array group 9 that simultaneously detects injection errors from a plurality of nozzles. The ejection error detection gap array group is shifted up and down by an integer fraction of the interval between the ejection nozzles of the recording head as it goes to the right. A control circuit (not shown) causes a plurality of ink droplets to be continuously ejected simultaneously from a plurality of ejection nozzles onto the ejection error detection gap row at the maximum usable frequency of the recording head. Ejection error detection is performed when the first ink droplet and the last ink droplet of the continuously ejected ink droplets adhere to each of two detection gaps and cover the entire detection gear train for all ejected ejection nozzles. Detection is performed by determining whether electrical continuity occurs. However, since the difference in height between the recording head and the detection electrode is not corrected, ink droplets are sequentially ejected into a group of detection gap rows slightly shifted in the height direction, and an ejection error occurs when continuity is established. It is determined that there is no. If continuity is not obtained even after ink is ejected for the number of detection gap rows, it is determined that an ejection error has occurred. By carrying out these embodiments, the objects of the present invention can be achieved. Next, the operation of the inkjet printer equipped with the ejection error detection device configured as described above will be explained. FIG. 3 is a configuration diagram showing one embodiment of an inkjet printer. The inkjet printer selectively ejects ink particles from a plurality of internal ejection nozzles 23 while scanning a preset recording section of a recording paper with a recording head 22 mounted on a carriage 21. Printing is performed on the recording paper 25 on the platen 24 facing the head, and the ejection error detection device detects the recording head every predetermined number of times, every predetermined time (for example, 60 seconds), or every page of the recording paper. Carriage 21 is moved in front of 26.
While moving, the position is detected by any ejection nozzle, and then ink is ejected sequentially from all the ejection nozzles.
The detection circuit detects an ink ejection error. If an ejection error is detected, the print head is moved to the front of the barge mechanism 27 outside the print area, and the ink inside the print head is forcibly flowed out by the purge mechanism 27, and the print head is to remove air bubbles, solidified ink, dust inside and outside the injection nozzle, etc. Further, if no ejection error is detected, the printing operation is executed again. [Effect of the Invention 1] As described above, according to the present invention, it is possible to reliably detect ink ejection direction errors, inability to eject, and incomplete ejection for recording heads with any number of ejection nozzles. Furthermore, the mutual positioning of the recording head and the ejection error detection device can be determined by ejecting multiple ink droplets from any ejection nozzle, so there is no need to make any adjustments when assembling the inkjet printer. , design becomes easier. According to the device of the present invention, it is easy to operate, and injection errors can be detected accurately and quickly. Furthermore, since recovery measures are automatically performed even after detection, it is easy for printer users to use.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention. FIG. 2 is a configuration diagram showing another embodiment of the present invention. FIG. 3 is a configuration diagram of an inkjet printer. FIG. 4 is a configuration diagram showing the detection principle of the present invention. FIG. 5 is a configuration diagram showing the principle of detecting incomplete injection according to the present invention. 14... Pull-up resistor, 15... Open collector buffer, 28... Guide shaft. Applicant: Seiko Epson Corporation 2 up and down! Inspection* q'...

Claims (1)

[Claims] In an inkjet printer jetting error detection method for detecting whether or not ink particles are jetted normally from a jetting nozzle of a recording head of an inkjet printer, in order to detect jetting mistakes, a plurality of jetting nozzles are A plurality of ink particles having an electrolyte as a component are continuously ejected from an ejection nozzle at the maximum usable frequency of the recording head toward a group of ejection error detection electrode pairs formed on opposing insulating substrates. A method for detecting ejection errors in an inkjet printer, characterized in that ejection errors of all ejection nozzles are detected by the presence or absence of electrical continuity between the electrode pairs caused by the first ink drop and the last ink drop.