JPH02179747A - Image recorder - 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 [Field of Industrial Application] The present invention relates to an image recording device having functions such as a facsimile machine, a copying machine, and a printer, and a multifunctional device having such functions;
The present invention relates to an image recording device used as an output device for a workstation or the like.

[Conventional technology]

The non-equivalent recording method has recently attracted attention because the noise generated during recording is so small that it can be ignored. Among them, there is a possibility of high-speed recording,
Moreover, the inkjet recording method is an extremely powerful recording method that can perform recording on so-called plain paper without requiring any specific fixing process.

A recording head applied to an inkjet recording device generally has a fine liquid ejection opening (orifice), a liquid path, an energy acting part provided in a part of this liquid path, and a droplet forming device that acts on the liquid in the acting part. It is equipped with an energy generation means for generating energy.

Energy generating means for generating such energy include recording methods using electromechanical transducers such as piezo elements, irradiating electromagnetic waves such as lasers, absorbing them into the liquid and generating heat, and generating heat due to the heat generated. A recording method using an energy generating means that ejects and flies droplets by action, or a recording method using an energy generating means that ejects a liquid by heating the liquid with an electrothermal converter such as a heating element having a heating resistor. etc. Among these, the recording head used in the inkjet recording method, which discharges liquid using thermal energy, has a high density array of liquid discharge ports (orifices) for discharging recording droplets to form flying droplets. This makes it possible to record with high resolution. Among these, a recording head that uses an electrothermal converter as a thermal energy generating means is easy to make the overall size of the recording head compact, and is based on IC technology and microelectromechanical technology, which have recently made significant advances in technology and reliability in the semiconductor field. It is possible to fully utilize the advantages of processing technology, and it is easy to make it long and planar (two-dimensional), so it is easy to make multi-nozzles and high-density packaging, and it is also highly productive in large quantities. It is also possible to provide an inkjet recording head that is inexpensive to manufacture and an apparatus having the head.

In this way, using an electrothermal converter as an energy generation means,
An inkjet recording head manufactured through a semiconductor manufacturing process generally has a liquid path corresponding to each orifice, and applies thermal energy to the liquid filling the liquid path for each liquid path to draw the liquid from the corresponding orifice. An electrothermal transducer is provided as a means for ejecting liquid to form flying droplets. Further, each of these liquid passages is configured to be supplied with liquid from a common liquid chamber communicating with each liquid passage.

Such a print head is left with ink remaining in a non-printing area during printing or inside an ink ejection opening such as a nozzle when not printing. At this time, the ink liquid in the nozzle dries and its viscosity increases, causing ink to fail to be ejected from the nozzle during recording. In response to this ejection failure, it is necessary to perform an ejection recovery process in which all nozzles of the print head are driven and ink is ejected in the same way as when recording an image on a recording paper. This is called idle ejection because it is not ejection for recording an image. Since ink flows out from the ejection port during idle ejection, it is desirable to provide a member that absorbs and stores this ink that flows out (hereinafter referred to as waste ink).

Specifically, a porous material made of polymer is used as an absorbing member that instantly absorbs the waste ink that flows out of the ejection port, and a porous material made of polymer is used as a storage member that absorbs the waste ink that is temporarily captured by the absorbing member. A storage container, a so-called waste liquid tank, is generally used for storage. The absorbing member is functionally disposed at a position facing the discharge port, and is communicated with a waste liquid tank provided at a predetermined position via a flexible tube or the like.

[Problem that the invention is trying to solve]

However, in an inkjet image recording apparatus, the conveying means for recording paper that regulates the recording surface is provided close to and opposite to the ink ejection opening, so when performing the above-mentioned idle ejection, the conveying means and the ink absorbing member are must be replaced.

Therefore, idle ejection is performed by allowing the ink absorbing member to face the recording head while the recording head or the conveyance means is moved. However, idle ejection must also be performed during recording in order to prevent nozzles that are not used for recording from failing to eject, taking into consideration the case where ink is not being ejected from all nozzles even during recording. In this case, since printing cannot be performed while the print head section or conveyance means is moving, the printing operation must be temporarily interrupted to prevent idle ejection, especially when printing multiple sheets at a time. In some cases, a delay in recording time (reduction in the amount of recording that can be recorded within a predetermined period of time) becomes a problem.

[Means to solve the problem]

According to the present invention, in an image recording apparatus that records an image by discharging a liquid, it is possible to prevent ink from being ejected from a recording head;
By discharging ink onto the conveyor belt between the recording sheets to perform the idle discharge performed for recovery, the idle discharge can be performed without interrupting the recording operation, thereby preventing and recovering the ink failure.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a schematic sectional view of an inkjet recording apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram of the vicinity of the recording/transporting portion. First, to explain the general configuration, in the figure, 301 is a scanner unit that reads a document and converts it into an electrical signal, and its printer unit 302
is given to the recording head section 305 as a drive signal. The paper feed unit 303 stores recording paper as the recording medium at that time, and feeds the recording paper sheet by sheet to the belt conveyance unit 304 when necessary. The recording paper is transferred to the belt conveyance section 304.
When passing through, an image is recorded by the recording head section 305, and the sheet is sent out to a tray 308 via a fixing sheet discharge section 307. Note that 306 is a recovery cap portion, which has a function to maintain the recording head portion 305 in a state where printing is possible at all times.

Here, when the print head is not printing, it is left alone with ink remaining inside its ink ejection openings such as nozzles. At this time, a capping means that can be bonded to the tip of the nozzle of the recording head is provided, and by performing this bonding when not recording, the recording head is sealed from the surrounding atmosphere with a lid covered, and the air layer at the bonded portion is sealed off from the ink. By filling the nozzle with steam to bring it to a saturated vapor pressure, the ink liquid inside the nozzle is prevented from drying out and from increasing in viscosity. Furthermore, with this method, in low-humidity environments or when recording is stopped for a long period of time, an increase in the viscosity of the ink cannot be avoided even if the above-mentioned capping is performed to prevent drying. It is difficult to prevent ink from not being ejected. To solve this problem of whether ink is ejected or not for the first time after a pause, a recovery pump (not shown) is driven to circulate ink under pressure and discharge ink from all nozzles of the recording head. An ink pressurized circulation means is also used. In addition, if the above-mentioned non-ejection condition is slight, all the nozzles of the head are driven, and ink is ejected in the same way as when recording on paper or the like. This is called idle ejection because it is not ejection for recording an image.

Next, the image recording sequence after turning on the power of this apparatus will be explained.

First, when the power of the image recording apparatus is turned on, the above-described ink pressurization and circulation recovery operation is performed.

This series of operations allows the device to be stopped for a long time before the power is turned on, and it is possible to prevent ink from sticking due to increased viscosity (increasing viscosity due to drying) or from non-ejection due to the generation of bubbles. This ink pressurization circulation operation is not executed only immediately after power is turned on. For example, if the ink is used in a high-temperature or high-humidity environment where it is likely to thicken, or if the power is turned on, it may be left unused or left unused for a long period of time, which may cause problems such as sticking and foaming. This problem is solved by using a timer means or the like to perform the above-mentioned pressurized ink circulation operation every fixed period of time (within an allowable period in which the above-mentioned problem does not occur, which is referred to as cycle time). Furthermore, a humidity sensor (not shown) is provided near the recording head unit 305, and its signals control changes in how many hours the ink pressurization circulation operation is performed and for how many seconds the ink pressurization time is performed. It is carried out. That is, when used in a low humidity condition, the cycle time is shortened or the ink pressurization time is lengthened. It has also been confirmed that changing both at the same time is more effective. When a recording start signal is input, a blank discharge operation is performed in which a fixed number of discharge pulses are given to all nozzles of all recording heads to cause them to discharge ink, thereby preventing non-discharge immediately before recording. The number of pulses for this idle ejection is also controlled by the signal from the humidity sensor, similar to the above-described ink pressurization circulation operation. That is, when the humidity is low, the number of idle ejection pulses is increased.

The difference in the effectiveness of the ink pressurization circulation operation and the idle ejection operation in preventing ejection failures is greater in the former, and therefore even the idle ejection operation cannot prevent ejection failures due to ink thickening, sticking, etc. This is the determining factor for the cycle time for the pressurized ink circulation operation.Therefore, when not in use,
The capping means isolates the ejection surface of the recording head from the outside air, prevents the ink from drying and sticking to some extent, and is configured so that all the nozzles of the head can eject with only a dry ejection operation.

In order to start printing on the recording paper, the recording paper stored in the cassette 411 is fed by the pickup roller 412, passes through the transport rollers 413 and 414 and the guide section 419, and then passes through the stopped registration roller pair. 4. It is fed into the nip section of 15 and 416. Here, after the leading edge of the paper comes into contact with the nip portion of the pair of register rollers 415 and 416, the sheet continues to be transported by the transport roller 41 for some time.
3, 414, and a loop is formed in the guide portion 419 by that amount. This operation is a means of register alignment that is normally performed by electrophotographic copying machines, etc., and the loop force is used to align the leading edge of the sheet and correct paper skew.

Next, the pair of register rollers 415, 416 starts rotating, and the conveyor belt l-101 is sent out onto the upper surface via the guides 417, 418, but this pair of register rollers 415. Based on the rotation start signal of 416, a signal to start scanning the original and a print start signal for each of the heads Ic, IM, IY, and IBk are issued. The recording paper fed onto the conveyor belt 101 is sequentially moved from the leading edge to the conveyor belt 810 by electrostatic adsorption force.
The recording heads IC,, 1M, IY,
Printing is performed when passing directly under IEk. After that, the paper is conveyed to the fixing/discharge unit 307, but when the paper is passed from the conveyance belt 101 to the guide 213, the diameter of the drive roller 102 is set to be relatively small (the stiffness of the paper is This is done by means of so-called curvature separation, which causes natural separation.

Here, the diameter of the drive roller 102 is the distance traveled by the surface of the belt 101 that is frictionally driven by one rotation of the drive roller 102 between the discharge ports of the first head IC and the fourth head IBk. Set the distances to be equal. This is done in consideration of the fact that if there is an eccentric component in the diameter of the drive roller 102, it will occur as a registration shift on the image. Ideally, the surface of the belt 101 should be driven by one rotation of the drive roller by the distance between the discharge ports of adjacent heads, but in consideration of mechanical strength, the minimum diameter of the drive roller 102 is There is a limit to the value,
Taking this into consideration, it becomes relatively large. This requires three times the distance between the four heads, resulting in an increase in the size of the device. Therefore, consideration is given to the distance between the first head and the fourth head, which are the farthest apart and include many other causes of registration misalignment. However, it may be between the first head and the third head (or, of course, it may be between adjacent heads (but is not limited to the above. However, the diameter of the drive roller and Some consideration must be given to the distance between heads.

The recording paper that has been printed and recorded as described above is transferred to the paper ejection roller 21.
1.212, the paper is transported, kicked out, and stacked on the tray 420.

Next, the sequence for preventing non-discharge mentioned above will be explained. As mentioned above, when the power is turned on to the apparatus, an ink circulation recovery operation is performed in consideration of the case where the apparatus has been left in a non-recording state for a long time. Thereafter, the device waits in the capping state until a recording start signal is input, but during this time, when the fixation timer means is activated, the circulation recovery operation is performed again. This fixed timer means prevents ejection failure due to increased ink viscosity when a non-recording state continues for a long time even after the power is turned on, and it varies depending on the characteristics of the ink and the environment in which it is used. is on the order of hours. Next, when a recording start signal is input, the conveyor belt rotates and, at the same time, idle ejection is performed on the conveyor belt. The idle ejection ends before the recording paper passes directly below the recording head, and then printing is performed on the recording paper. A cleaner 120 equipped with an ink absorber 119 cleans the surface of the conveyor belt to which the idle ink has adhered.

The ink absorber 119 is formed of a continuous porous member such as polyvinyl formal resin, and the absorbed ink flows out and is collected from the opening 120. Therefore, the idle ink does not remain on the surface of the conveyor belt and stain the recording paper. If the generator timer is activated during recording, empty ejection is performed again. The distance between normal recording paper and recording paper is 50 to 1
Although the recording sheets are conveyed with a gap of about 50 mm between them, idle ejection performed during recording is performed toward the conveyance belt between the recording sheets.

Therefore, there is no need to interrupt recording due to idle ejection.

The above-mentioned ejection timer is used for recording, taking into consideration the case where not all nozzles are ejecting during recording, and in order to prevent a nozzle that is used for recording from failing to eject, the timer means is used to keep the ejection constant from the previous empty ejection. This will be done after hours. This is to recover from a minor discharge failure using a dry discharge means, and is a relatively short period of time on the order of several minutes. When the set number of images have been recorded in this way, the head-down state is maintained for a certain period of time set by the remaining firing timer.
Waits for the next input signal to start recording. Here, if a recording start signal is not input within the set time of the output/remaining timer, the head is raised and the capping state is entered. Further, if a signal to start recording is input within the set time, recording is started immediately and the image recording sequence as described above is taken. Here, the remaining timer is the time from the previous empty ejection until the end of image recording, which is subtracted from the timer time, and is the standby time when the head is down and not capped. Therefore, the time is set slightly shorter than the calculated subtraction time, taking into account that the ink dries easily.

〔Effect of the invention〕

As described above, according to the image forming apparatus of the present invention, the recording operation can be interrupted by directly ejecting ink between the recording sheets on the conveyor belt for conveying the recording sheets to the inkjet head section. This has the effect of being able to prevent and recover from ink ejection failure of the recording head without any problems.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an inkjet recording apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram for explaining the present invention.

Claims (2)

[Claims] (1) In an image forming apparatus having a conveying means for conveying recording paper to a recording head section for recording an image by ejecting liquid, and a cleaning means for cleaning the surface of the conveying means, An image recording device characterized in that ink is ejected onto the surface of the device. (2) The image recording apparatus according to claim 1, wherein ink is ejected between recording sheets.