JPH0222066A - Ink jet printer - Google Patents

Abstract

PURPOSE:To keep the recording grade of an ink jet printer to enhance the reliability thereof by providing a detection means for detecting whether nonemission is generated in the first recording head and further providing the second recording head driven when nonemission is generated so as to record the omitted dot part caused by said nonemission. CONSTITUTION:A current is allowed to flow to the heat generator 6 of the first recording head nozzle 1 and an ink liquid droplet is emitted from said nozzle 1 to be bonded to recording paper 4 to perform recording. At this time, a photosensor 2 detects whether the ink liquid droplet is emitted from the first recording head nozzle 1. Next, when the nonemission of the ink liquid droplet is detected by the photosensor 2, a current is allowed to flow to the heat generator 12 of the second recording head nozzle 3 and the ink liquid droplet is emitted from the second recording head nozzle 3 to be bonded to the recording paper 4 at an omitted dot part and desired recording is performed with definite grade.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inkjet printer, and more particularly to an inkjet that is capable of recording on missing recording dots of an inkjet printer.

[Prior Art] An inkjet printer that records characters or images by jetting or ejecting ink droplets toward a recording medium such as recording paper is capable of directly recording on plain paper; It has many advantages such as quiet operation and low running costs.

Therefore, inkjet printers are attracting attention as a recording means for word processors and the like.

[Problems to be Solved by the Invention] However, in conventional ink sheet printers, the nozzle of the ink ejecting unit is left in the atmosphere when not recording, so the water contained in the ink does not evaporate. This may increase the viscosity of the ink, causing it to dry and solidify. As a result, the ejection conditions may vary, and in severe cases, the nozzle may become clogged.

Improving the ink may be considered as a countermeasure to this problem, but it is said that the physical properties of the ink will change and this will affect the formation of ink particles.

Further, dirt may enter or adhere to the ink nozzle, causing clogging.

Furthermore, in an inkjet printer equipped with a recording head having multiple nozzles, if one or more of the multiple nozzles fails to eject, it is necessary to maintain the recording quality by The inkjet printer may become unusable until it is cleaned or the entire recording head is replaced. Under such conditions, the frequency of maintenance of the recording head increases, which also leads to a decrease in the operational efficiency of the inkjet printer.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an inkjet printer that solves the above problems, maintains high recording quality by appropriately preventing the occurrence of missing dots due to ink clogging, and has good operational efficiency. It is in.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides an inkjet printer that records by ejecting ink droplets onto a recording medium based on an ejection signal. a detection means for detecting whether or not an ejection failure has occurred in the first recording head; and a second recording head that is driven to record a missing dot portion caused by the ejection failure when the detection means determines that an ejection failure has occurred. It is characterized by comprising a recording head.

[For use] According to the present invention, by providing a detection means for detecting clogging of the recording head and a recording head nozzle for recording the missing dot portion based on the output result of this detection means, it is possible to quickly detect clogging. It was possible to prevent the occurrence of missing dots due to non-ejection of recording dots.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of an inkjet printer of the present invention.

In FIG. 1, 1 is a first recording head nozzle that discharges ink droplets, 2 is an optical sensor that detects whether ink droplets are being discharged from the first recording head nozzle 1, and 3 is an optical sensor. 2, when it is detected that ink is not ejected from the first recording head nozzle, the second recording head is driven to perform recording on the recording paper 4 to be recorded on the missing dot portion. It's a nozzle.

In such a configuration, when print data is sent to the inkjet circuit at a certain timing, the transistor 5 is driven in accordance with the print data, and current flows through the heating element in the first print head nozzle 1. It will be done. This current heats the heating element in the first recording head nozzle,
Stop powering the heater when the number of bubbles on the heating element approaches its maximum. Ink liquid is sent toward the orifice in front of the nozzle in accordance with the size of the generated bubble.

As a result, ink droplets are ejected from the first recording head nozzle 1 and adhere to the recording paper 4, thereby performing recording. First recording head nozzle 1. Along with the scanning of the carriage (see Figure 3) on which the second print head nozzle 3 and optical sensor 2 are mounted, it is detected whether ink droplets are ejected from the optical sensor 2 or the first print head nozzle 1. do. At this time, the offset between the first recording head nozzle 1 and the optical sensor 2 is corrected by the delay circuit 7, and the corrected data and the detection signal of the optical sensor are compared at the EXOR gate 10 to determine whether they match. , that is, when the optical sensor ejects an ink droplet from the first recording head nozzle, the signal output from the EXOR gate 10 is ''
It becomes L°゛ level, and the second
No ink droplets are ejected from the recording head nozzles 3.

Next, if the first print head nozzle does not eject an ink droplet even if print data that causes an ink droplet to be ejected is sent to the first print head nozzle 1, the non-ejection of the ink droplet is detected using an optical system. Detected by sensor 2. At this time, the offset a between the recording head nozzle of Sl and the optical sensor is corrected by the delay circuit 7, and the corrected recording data and the signal from the optical sensor are compared. In this case, since the two do not match, the signal output from the EXOR gate IO is “
H” level.Next, the delay of the offset C between the optical sensor 2 and the second recording head nozzle 3 is corrected, and the delay circuit corrects the offset of the first recording head nozzle and the second recording head nozzle. 9. By passing the output of the delay circuit 9 and the output of the delay circuit 8 through the AND gate 11, a current is caused to flow through the heating element of the second recording head nozzle 3. As a result, the output of the second recording head nozzle Then, ink droplets are ejected and recording is performed on the recording paper 4 in the missing dot area.

FIG. 2 is a signal waveform diagram for explaining the operation of the inkjet printer according to this embodiment.

FIG. 2 (8) is a signal waveform diagram of recording data.

13 indicates a recording dot, and 14 indicates a missing dot due to clogging of the recording head nozzle. The missing dots 14 are shown as broken lines because if clogging occurs, they will not be recorded according to the signal waveform diagram shown in FIG. 2(A).

FIGS. 2(B) and 2(C) are signal waveform diagrams output from delay circuits 7 and 8, respectively. FIG. 2(D) is a signal waveform diagram output from the optical sensor 2. Figure 2 (
The signal waveform diagram of the delay circuit 7 shown in B) and FIG. 2(D)
EXOR gate 1 with the signal waveform diagram of optical sensor 2 shown in
When compared at 0, if the signal waveform diagrams of both do not match, it will be at the "L'° level, and if the signal waveform diagrams of both do not match, it will be at the "H" level, so EXO
The signal waveform diagram output from the R gate 10 is shown in Figure 2 (E).
It becomes as shown in .

Furthermore, it is assumed that a signal waveform diagram output from the delay circuit 9 is shown in FIG. 2(F). At this time, the signal waveform diagram from the delay circuit 8 (see FIG. 2 (C)) and the signal waveform diagram from the delay circuit 9 are compared by the AND gate 11, and both signal waveform diagrams are "H". If not, the level is “L”, and if both signal waveform diagrams are “H”, the level is “H”.
Since the signal is at the °° level, the signal waveform output from the AND gate 11 is as shown in FIG. 2(G).

FIG. 3 shows an example of the mechanical configuration of an inkjet printer to which this embodiment is applied. In FIG. 3, reference numeral 15 indicates the first recording head nozzle 1. a carriage on which the optical sensor 2 and the second recording head nozzle 3 are mounted; 16 is a platen;
Reference numeral 17 denotes a paper feed motor, which moves the recording paper via paper feed rollers 18 that nip the recording paper 4. Reference numeral 19 denotes a drive motor for moving the carriage 15.

In this configuration, ink droplets are ejected from the first recording head nozzle 1 while moving the carriage 15 from the left side to the right side. When the optical sensor 2 detects the non-ejection of ink droplets from the first recording head nozzle 1, the second recording head nozzle 3 is used to record the missing dot portion caused by the first recording head.

Upon completion of one line of recording, the paper feed motor 17 advances the recording paper 4 by one line. At that time, the print head nozzle is returned to the print start position on the left side in FIG. 3, and print by ejecting ink droplets is resumed. In this way, the missing dot portion of the first recording head can be recorded by the second recording head nozzle 3.

In this embodiment, a case has been described in which one recording head nozzle is clogged, but it goes without saying that the present invention can be applied very effectively and easily even if an inkjet printer has a plurality of recording head nozzles.

Further, since there are very few cases where nozzles in the same raster of the first print head and the second print head fail to eject, reliability is improved.

In addition, the present invention can of course be applied to inkjet printers that employ any liquid ejection method or recording method.

For example, in the upper case, the recording head uses the heating element 6 as a means for generating liquid ejection energy, but the recording head may be equipped with an electrical/mechanical transducer such as a piezo element. Also, in the upper part, recording is performed when moving to the right in Fig. 3, but reciprocating recording may also be performed, in which case, when moving to the right and when moving to the left. It is also possible to configure the first and second recording heads to have opposite functions. Furthermore, the present invention can be applied not only to such so-called serial type printers but also to inkjet printers in the form of line printers having so-called full multi-type recording heads in which nozzles are aligned over the entire width of the recording medium. In this case, full multi-type recording heads are arranged in multiple stages along the conveyance path of the recording medium, so that it is possible to avoid misalignment.

[Effects of the Invention] As explained above, according to the present invention, a detection means for detecting ejection failure of the recording head and a recording head nozzle for recording the missing dot portion based on the output result of the detection means are provided. As a result, it was possible to quickly prevent the occurrence of missing dots due to non-ejection of recording dots.

Therefore, not only the recording quality of the inkjet printer is maintained, but also the reliability can be improved and the operational efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the inkjet printer of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation of the inkjet printer of the present invention, and FIG. 3 is a schematic diagram of the inkjet printer of the present invention. FIG. 2 is a perspective view showing a configuration example. DESCRIPTION OF SYMBOLS 1... First recording head nozzle, 2... Optical sensor, 3... Second recording head nozzle, 4... Recording paper, 5... Transistor, 6... Heating element, 7 .8.9...Delay circuit, 10...EXOR gate, 11...AND gate, 12...heating element, 13...printed dot, 14...missing dot, 15...carriage , 16...Platen, 17...Paper feed motor, 18...Paper rotation roller, 19...Drive motor. Showing the 01 row of Honkorizuki's ink sheet
Yodone Menkuni Figure 3 1 Yuan 818 Oval

Claims (1)

[Claims] In an inkjet printer that performs recording by ejecting ink droplets onto a recording medium based on an ejection signal, a first recording head, a detection means for detecting whether or not an ejection failure has occurred in the first recording head; An inkjet printer comprising: a second recording head that is driven to record a missing dot portion caused by the ejection failure when it is determined by the means that the ejection failure has occurred.