JP2812491B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is provided with a cleaning wiper for wiping an ejection port surface to prevent clogging of an ink ejection port of a recording head and defective ink ejection. To an ink jet recording apparatus.

[Conventional technology]

An ink jet recording apparatus that performs recording by discharging ink droplets from a plurality of ink discharge ports of an ink jet recording head to a recording medium such as recording paper based on recording information has excellent quiet operation noise and a printer or the like. It has a wide range of uses such as facsimile. Further, by using a plurality of recording heads corresponding to a plurality of color inks, full-color recording becomes possible, and it is also used in a color copying machine and the like.

Further, the ink jet type recording apparatus enables high-speed, high-definition recording and large-screen recording.

FIG. 9 is a schematic perspective view showing a conventional example of a main configuration of a serial print type color ink jet recording apparatus provided with means for removing droplets, foreign matter, and the like on the recording head surface by a cleaning wiper.

In the figure, a recording head 12Y that discharges yellow (Y) ink, a recording head 12M that discharges magenta (M) ink, a recording head 12C that discharges cyan (C) ink, and black (K) color ink The recording head 12 </ b> K that discharges the
Moves along the guide shaft 14 to the left and right of the recording device. The recording paper 15 is transported by transport rollers 16 disposed above and below the recording apparatus, and these rollers form a recording surface facing the ink ejection port surface of the recording head.

In forming pixels on recording paper, it is possible to superpose ink in the order of yellow, magenta, cyan, and black as the carriage 13 moves, and to record a multicolor image by combining these inks. Can be. The ejection timing of each color ink is determined based on a read signal of the encoder 17.

The cap 18 provided at the home position of the carriage,
It is formed of a non-breathable elastic body, and when printing is not performed, the discharge port of the print head is sealed from the outside to prevent ink sticking, thickening or dust adhesion due to evaporation of ink water, and keep the ink discharge state good. To do. At this cap position, in order to prevent clogging of the ejection port that is used less frequently in the recording head, idle ejection performed at predetermined intervals during recording, or a pump with the cap capped.
It is also possible to perform an ejection recovery operation such as ink suction by 19.

The cleaning wiper 21 disposed adjacent to the cap 18 is made of a plate-like elastic body such as urethane rubber and is supported by the holder 20. The cleaning wiper 21 is used to remove foreign matter such as ink, dew, or dust adhered or adhered to the surface near the ink discharge port from the ink discharge port surface. Can move back and forth. Accordingly, the cleaning operation can be performed by bringing the cleaning wiper 21 into contact with the discharge port surface as the carriage 13 moves as necessary.

FIG. 10 is an enlarged view of the ejection port forming surface of the recording head immediately after the ejection of the ink.

The recording head shown here is provided with a heating element (electric heat conversion element) as an ejection energy generating element, locally heats the ink by applying an electric signal to the heating element, and uses the heat energy to generate bubbles. Is generated, and ink is ejected from the ejection port in accordance with the change in the state of the bubble.

In the figure, 2 is a top plate, 3 is an adhesive layer, 4 is a discharge port,
Reference numeral 5 denotes a partition, 6 denotes a heater substrate on which the electrothermal converter is provided, and 7 denotes a substrate.

The configuration of the recording head is not limited to those described above. For example, energy used for ejecting ink may be mechanical pressure, laser energy, or the like.

In the case of recording by an ink jet recording apparatus, the ink droplets 10 may adhere to the ejection opening surface of the recording head due to a small ink droplet liquid (ink mist) unnecessary for recording or splashing of ink from a recorded image. In particular, in a recording apparatus that discharges ink by using thermal energy, the temperature of the ink becomes high, and dew may be formed on the discharge port surface due to water vapor generated from the ink or recording paper to which the ink adheres. , Due to these factors
Is relatively large.

In such a case, the ink droplets 10 that have grown greatly due to the vibration of the carriage movement or the like may close the ejection openings as indicated by 11 in the drawing, making it impossible to eject the ink or causing the ejection direction to be deflected. This causes a discharge failure.

For this purpose, the wiping operation of the cleaning wiper 21 is performed while returning the carriage toward the home position at the time of each scan recording to remove ink droplets present on the ejection opening surface, thereby preventing ejection failure.

[Problems to be solved by the invention]

In the above-described conventional example, the wiping operation is performed, for example, for each scan even when the print width is small, the print amount is small, and almost no liquid droplets adhere to the discharge port surface.

For this reason, there has been a problem that the abrasion of the discharge port surface of the cleaning wiper and the recording head is severe, causing a cleaning failure, or the discharge port surface of the recording head is deteriorated, resulting in defective discharge.

Further, if the cleaning wiper is moved back and forth for each scan, it takes time for the cleaning wiper, and as a result, there is a problem that the printing speed is reduced.

The present invention has been made to solve the above problems. The present inventor has paid attention to the fact that the ink droplets 10 that cause ink ejection failure have a large image recording width or that the larger the image recording amount, the faster the growth thereof. By controlling the timing at which the cleaning wiper removes droplets, foreign matter, etc. from the ejection port surface in accordance with the detected recording amount, unnecessary wiping operation when the recording amount is small is eliminated, and wear of the cleaning wiper is prevented. It is an object of the present invention to provide an ink jet recording apparatus capable of preventing deterioration of a recording head and improving a recording speed.

[Means for solving the problem]

Therefore, in the present invention, a print head having a plurality of discharge ports for discharging ink is used, and in an ink jet recording apparatus that performs recording by discharging ink while scanning the recording head on a recording medium, a wiper is used. A cleaning unit for wiping the discharge port surface on which the plurality of discharge ports of the print head are arranged with the wiper, and cleaning the discharge port surface; Detecting means for detecting the amount of movement of the print head from the start of printing by discharging ink to the end of printing by discharging ink last, and printing in the scan based on the amount of movement detected by the detecting means. Means for determining whether or not to perform cleaning by the cleaning means after execution, and when the movement amount is equal to or more than a predetermined amount, the cleaning means is provided after the scanning. Determining means for performing cleaning by the cleaning means, and control means for performing cleaning by the cleaning means after the scanning when the determining means determines to perform cleaning by the cleaning means. And

(Operation)

According to the above configuration, each time the print head performs one scan, the amount of movement of the print head from the time when ink is first ejected to start printing in that scan to the time when ink is finally ejected to finish printing Is controlled based on the detected movement amount, and whether or not to perform cleaning by the wiper after the scanning is performed. Therefore, when the detected movement amount is small, the ink ejection amount is small, and the ink adhering to the ejection port surface is small. Since it can be determined that the number of droplets and the like is small, it is possible to control so that cleaning after the scanning is not performed.

〔Example〕

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

FIG. 1 is a block diagram showing an example of a configuration of a control system of an ink jet printing apparatus according to an embodiment of the present invention. Here, reference numeral 100 denotes a control circuit for controlling each unit of the apparatus, and includes a CPU for executing a processing procedure and the like to be described later, a ROM storing programs and other fixed data corresponding to the processing procedure, and a RAM for work such as arithmetic operations. doing.

Reference numeral 101 denotes a transport unit including a motor and the like for transporting the recording medium 15 in the sub-scanning direction, 102, a carriage drive circuit for scanning and driving the carriage 13, and 103, for driving the electrothermal transducer of the recording head 12. Head driver, 104
Is a pump driving circuit for driving a pump 19 used for the recovery operation of the recording head, 105 is a cap driving circuit for moving the cap 18 to join / remove the recording head 12, and 106 is via the holder 20 A cleaning wiper driving circuit for moving the cleaning wiper 21 to make contact with / separate from the recording head 12, and a detection circuit 107 for detecting a recording amount.

FIG. 2 is a flowchart showing an example of a sequence of removing droplets and foreign matter on the recording head surface by a cleaning wiper of the ink jet recording apparatus according to one embodiment of the present invention. Here, the case of an apparatus having a maximum recording width of 500 mm is shown.

First, in step S201, it is determined whether a recording signal has been sent. If a print signal is received, a recovery operation by ink suction is performed in step S202, then the cap 18 is detached from the print head 12, and the ink droplets adhering to the discharge port surface of the print head are moved while moving the carriage 13. In step S203, which is removed by the cleaning wiper 21 (hereinafter referred to as wiping), printing for one scan is performed, and in step S204, the printing width at this time is detected. Here, the printing width is the amount of movement of the carriage when printing is performed. That is, in general, in a printing apparatus such as a graphic printer, printing is performed halfway without moving the entire width of 500 mm depending on print data of one scan, and if the print data thereafter is "0", the carriage returns there. In many cases, such a configuration is adopted, and the movement amount until the return is taken as the recording width. The detection of the recording width is performed based on the count amount read by the encoder provided for controlling the ink discharge position.

In step S205, it is determined whether the recording width is 125 mm or more,
If it is 125 mm or more, the carriage 13 is moved to the home position in step S206, wiping is performed in accordance with this movement in step S207, and stopped at the home position. Next, in step S208, idle ejection is performed to prevent color mixing by wiping and to prevent ink sticking to unused nozzles. If it is determined in step S205 that the recording width is less than 125 mm, the carriage 13 is returned to the home position in step S212, and only idle discharge is performed in step S208.

In step S209, it is determined whether or not the printing has been completed. If the printing has been completed, the cap is closed in step S210 to prevent the ink from sticking to the print head, and the process waits until the next print signal is received. If the recording has not been completed, the process returns to step S203 to continue the recording.

FIG. 3 is a flowchart showing another sequence of the wiping operation by the cleaning wiper. Here, the case of an apparatus having a maximum recording width of 500 mm is shown.

In this process, first, in step S301, a counter configured in, for example, a RAM inside the printing apparatus is reset, and
If it is determined in 302 that the recording signal has been sent, step S303
Then, a recovery operation and a wiping operation by ink suction are performed in the same manner as in the above-described processing, and printing for one scan is performed in step S304. Then, in step S305, the image recording width is detected from the count amount read by the encoder as described above. Perform

Next, in step S306, it is determined whether or not the recording width has been recorded at 125 mm. If the determination is affirmative, subsequently, at step S307, it is determined whether or not the recording width has been recorded at 250 mm. Step S307
If it is determined that 250 mm or more is recorded in step S308,
, A wiping operation is performed in step S309, idle discharge in step S310, and step S311.
After the counter is reset, the process proceeds to step S312.

If it is determined in step S306 that 125 mm has not been recorded, the counter 1 is added in step S318, and step S3
At 19, it is determined whether the counter is 4 or not. When the counter reaches 4, the process proceeds to step S308, and when the counter is less than 4, the process proceeds to step S320, the carriage returns without performing the wiping operation, only idle discharge is performed in step S330, and the process proceeds to step S312.

If it is determined in step S307 that 250 mm has not been recorded, 1 is added to the counter in step S314, and step S3 is executed.
At 15, it is determined whether the counter is 2 or not. When the counter reaches 2, the process proceeds to step S308. When the counter is less than 2, the process proceeds to step S316. After the carriage returns without performing the wiping operation, only idle discharge is performed in step S317, and the process proceeds to step S312.

In this embodiment, when the recording width is less than 125 mm, the wiping operation is performed every four scans. When the recording width is 125 mm or more and less than 250 mm, the wiping operation is performed every two scans, and the recording width is 250 mm. In the above case, the wiping operation is performed at each scan.

In the above two embodiments, the amount of movement of the carriage with respect to printing is used as the means for detecting the printing amount, but the amount of print data indicated by a control command signal transmitted from the host computer to the apparatus before the image signal is used. The recording amount can also be detected.

 For example, the control command is set as follows.

Here, ESCγ is a setting command indicating that the signal to be transmitted is a color bit image signal. DATA LENGTH is a 3-byte parameter and is 1
Indicates the total number of bytes of image data for the line, and the maximum recording width is 500 mm and the data length when recording at the maximum width with a device that records 16 dots per mm is (OOH), (OFH), (A
OH), which indicates 4000 bytes in this case.

CR indicates that one line of image data has been transmitted, and the image data of the next line can be transmitted continuously. The printing apparatus performs printing upon receiving data for one scan. END is a signal indicating the end of signal transmission.

FIG. 4 shows a flowchart of a sequence of a wiping operation by the cleaning wiper of the ink jet recording apparatus in the present embodiment.

When the recording signal is received in step S401, step S4
After performing the recovery operation in 02, the cap is opened, and ink droplets adhering to the ejection port surface are removed by a cleaning wiper. “DATA LENGT described earlier in step S403
H "is 2000 bytes or more, if DATA LENGTH is 200
If it is 0 bytes or more, an image for one scan is recorded in step S404, and after returning the carriage in step S405,
Wiping is performed by the cleaning wiper in step S406, and idle discharge is performed in step S407. Step S4
Steps S404 to S407 until the recording is determined to be completed in 08
It is repeated.

If "DATA LENGTH" is less than 2000 bytes in step S403, the counter of the printing apparatus is reset in step S410, printing for one scan is performed in step S411, and after the carriage returns in step S412, step S4 is performed.
At 13, the counter is incremented by one.

It is determined whether or not the counter is 2 in step S414. If it is determined that the counter is 2, wiping is performed in step S415, idle ejection is performed in step S416, and it is determined whether or not recording is completed in step S417. If the counter is other than 2, the flow returns to step S411 without performing wiping and idle discharge, and performs the next image recording.

In this embodiment, when "DATA LENGTH" is 2000 bytes or more, wiping and idle discharge are performed at each scan. However, when "DATA LENGTH" is less than 2000 bytes, wiping and idle discharge are performed every two scans. Perform

As another embodiment, the temperature of the recording head can be used as a means for detecting the recording amount, and FIG. 5 shows the configuration of the recording head in this case.

In the figure, 4 is a discharge port, 3 is an adhesive layer, 5 is a partition,
2 is a top plate, 6 is a layer for arranging the electrothermal converter, 7 is a substrate,
Reference numeral 8 denotes a thermistor, and the temperature of the recording head is detected by the thermistor 8.

FIG. 6 is a diagram showing the relationship between the recording amount and the temperature of the recording head. As shown in FIG. 6, a curve 1a shows the case where so-called solid recording is performed, and the temperature of the recording head immediately becomes saturated. . The curve 1b shows a case where the dot formation rate per unit area is 30%, and the temperature of the print head does not become saturated even after performing scanning printing of a plurality of rows.
Thus, it is possible to provide a means for knowing the recording amount by detecting the temperature of the recording head.

The temperature of the recording head shown in FIG. 6 shows a change when an image having the same dot recording density is recorded. Even in the state of the curve 1b, if a solid image portion is obtained, the recording head temperature rises sharply. However, even in the state of the curve 1a, the temperature drops in an image portion where dots are hardly formed.

FIG. 7 is a flowchart showing a sequence of a wiping operation by the cleaning wiper of the ink jet recording apparatus of the embodiment described above.

When the recording signal is received in step S701, step S7
In step 02, the cap is opened and the recovery operation is performed. In step S703, printing for one scan is performed. Step S7
At 04, the temperature is detected by the thermistor 8 shown in FIG.
Step S705 in the detected temperature T _H is the T _O (the example shown in Figure 6
If it is equal to or higher than 45 ° C.), after the carriage return in step S706, a wiping operation is performed in step S707.

If when the printhead temperature lower recording dot density is less than T _O, or the recording head temperature in the image area in which the recording dot density is lowered falls below T _O, after the return carriage in step S720, to step S708 move on.

As still another embodiment, the recording signal amount can be used as a means for detecting the recording amount, and the sequence of the wiping operation in this case is shown in FIG.

Here, an apparatus in which the maximum recording width is 500 mm, 16 dots per 1 mm are recorded, and the number of ejection ports of the recording head is 16 will be described.

In step S803, the number of dots to be recorded is counted using a signal sent from the recording signal to the driver circuit of the head. The counter has four counters so that yellow (Y), magenta (M), cyan (C), and black (K) signals can be separately counted. Maximum recording width is 500mm
The number of dots when a solid image is recorded is 12 per color.
It becomes 8000 pieces. As a result, the number of dots is 64 in step S805.
If there is at least one print head of 000 or more, a wiping operation is performed in step S807.

If the number of dots is 64,000 or less for all colors, the wiping operation is not performed.

Further, in addition to the calculation amount detecting means described above, by detecting the reflectance in a predetermined range of the recorded recording paper by a sensor, it is possible to determine that the recording amount is large when a high reflectance is obtained. Based on this control, it is possible to control the wiping timing described above.

〔The invention's effect〕

As described above, according to the present invention, the recording head 1
In each scan, the amount of movement of the print head from the first discharge of ink in the scan to start printing and the last discharge of ink to the end of printing are detected, and based on the detected amount of movement, Since it is controlled whether or not to perform the cleaning by the wiper after the scanning, when the detected movement amount is small, the ink ejection amount is small, and it can be determined that the ink droplets and the like attached to the ejection port surface are also small. It is possible to control not to perform cleaning after scanning.

As a result, unnecessary wiping operation can be reduced as much as possible to prevent the abrasion of the wiper, the deterioration of the ejection opening surface of the recording head, and the improvement of the throughput.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one configuration of a control system in an ink jet recording apparatus according to one embodiment of the present invention. FIGS. 2 and 3 are wiping operations by a cleaning wiper of the ink jet recording apparatus according to one embodiment of the present invention. FIG. 4 is a flowchart showing a sequence according to another embodiment of the wiping operation by the cleaning wiper of the ink jet recording apparatus according to one embodiment of the present invention, and FIG. 5 is a further embodiment of the present invention. FIG. 6 is a schematic perspective view showing a configuration of a main part of a recording head provided with a temperature sensor used in the present invention. FIG. 6 is a diagram showing a relationship between a recording amount and a recording head temperature. FIG. 7 and FIG. A wiping operation by a cleaning wiper of an ink jet recording apparatus according to another embodiment FIG. 9 is a schematic perspective view showing a main part of a serial print type color ink jet recording apparatus provided with means for removing droplets and foreign matter on the recording head surface by a cleaning wiper, and FIG. 10 is a cleaning wiper. FIG. 4 is a schematic front view showing a state of a discharge port surface of a recording head when droplets and foreign substances are not removed by the method. 2 ... top plate, 3 ... adhesive layer, 4 ... discharge port, 5 ... partition wall, 6 ... layer on which electrothermal transducer is disposed, 7 ... substrate, 8 ... thermistor, 12 ... recording head, 13 ... Carriage, 14 ... Guide shaft, 15 ... Recording paper, 16 ... Convey roller, 17 ... Encoder, 18 ... Cap member, 19 ... Pump, 20 ... Holder, 21 ... Cleaning wiper, 100: Control circuit 102: Carriage drive circuit 103: Head driver 104: Pump drive unit 105: Cap drive circuit 106: Cleaning wiper drive circuit

Claims (2)

(57) [Claims] 1. An ink jet recording apparatus which uses a recording head having a plurality of ejection ports for ejecting ink, ejects ink while scanning the recording head on a recording medium, and performs recording, has a wiper. A cleaning means for wiping an ejection opening surface of the recording head, in which a plurality of ejection openings are arranged, with the wiper, and cleaning the ejection opening surface; Detecting means for detecting the amount of movement of the print head from the start of ejection and recording to the end of ejection of ink and the end of recording; and execution of printing in the scan based on the amount of movement detected by the detecting means. Determining whether or not to perform cleaning by the cleaning unit after the scanning. When the moving amount is equal to or more than a predetermined amount, cleaning by the cleaning unit is performed after the scanning. Determination means for performing the cleaning, and control means for performing cleaning by the cleaning means after the scanning when the determination means determines to perform cleaning by the cleaning means. Ink jet recording device. 2. An ink jet recording apparatus according to claim 1, wherein said recording head uses thermal energy as energy used for discharging ink.