JP2001113725A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect whether or not ink drops are ejected from all of the nozzles even when using a system wherein a light emitting device and a light receiving device are separated. SOLUTION: Ink drops are sequentially ejected from each nozzle of a head 2 in such a manner that the ink drops block an optical beam which is emitted from a light emitting section 5 and is received by a light receiving section 6 that outputs a signal corresponding to the intensity of the optical beam. The pass-through of the ink drop is detected based on the output signal from the light receiving section 6 so that it is possible to detect whether or not the ink drops are correctly ejected. In the above structure an optical system 9 is provided between the light emitting section 5 and light receiving section 6 and then the diffracted optical beam is collected, thereby improving the detection accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet printing apparatus, and more particularly to an ink-jet printing apparatus having a large number of nozzles for continuously printing at high speed and an ink-jet printer apparatus for performing light printing.

[0002]

2. Description of the Related Art In an ink jet printer, an image is formed by discharging a fine ink droplet from a fine nozzle onto a print medium and performing printing. As a method of driving the ink jet printer, a method in which ink is heated to cause film boiling and ink droplets are caused to fly by the pressure has already been put to practical use. Unlike the electrophotographic method, such an ink-jet method has a feature that an intended image can be stably obtained because there are few intervening components until an image is formed. On the other hand, ink may not be ejected due to clogging of the nozzles due to dust or thickened ink, disconnection of the heater in the above-described method of heating ink, or nozzle nozzles being covered with ink droplets. When ink non-ejection occurs, white streaks may occur due to non-ejection nozzles along the scanning direction of the inkjet head.

In order to detect such non-ejection of ink, a method of detecting non-ejection using a light emitting element such as an LED and a light receiving element such as a photodiode has been used. This stops the inkjet head at the predetermined detection position,
Ink droplets are ejected into a light beam that exits the light emitting element and reaches the light receiving element, and non-ejection is detected from the output of the light receiving element.

[0004]

However, when the distance between the light emitting element and the light receiving element is widened due to light diffraction or the like, it becomes difficult to detect the light emitting element and the light receiving element.

FIG. 7 is a cross-sectional view of an experimental apparatus for examining how the output of the light-receiving element changes as the position where the ink droplet is ejected from the light-receiving element moves away. FIG. 8 shows the experimental results. is there.

In FIG. 7, ink droplets are ejected from a head 36 into an ink receiver 37 from a nozzle 34 near the light emitting portion of the light beam 31 to a nozzle 35 near the light receiving portion while changing the nozzle for ejecting ink. FIG. 8 shows the result at that time. In FIG. 8, the vertical axis indicates the light amount ratio, and the horizontal axis indicates the distance from the light receiving unit (sensor) to the ink droplet. FIG.
It can be seen that, as the distance from the light receiving unit increases, the difference between the amounts of incident light with and without ink droplets becomes smaller, making it difficult to detect non-ejection. This is because the shadow of the ink passing through the beam is more affected by diffraction when it is closer to the light emitting portion.

As described above, when the distance between the light receiving element and the nozzle is large, it is difficult to detect non-discharge. Therefore, in the case of an ink jet printing apparatus in which a plurality of ink jet heads are arranged to increase the printing speed and the number of parallel nozzles is increased. Since the heads are arranged in the nozzle row direction, it is more difficult to detect non-discharge.

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional example, and has as its object to provide an ink jet printer capable of reliably detecting non-ejection of a nozzle far from a light receiving element.

[0009]

In order to achieve the above object, an ink jet printer according to the present invention has the following arrangement. That is, a head unit that ejects ink droplets from ejection ports arranged in series, a light emitting unit that emits a light beam so as to pass the ink droplets ejected from the head unit, and a light emitting unit that receives the light beam A non-discharge detection unit including a light receiving unit that outputs a signal corresponding to the intensity, and at least one optical system between the light emitting unit and the light receiving unit that collects a light beam is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet printer according to an embodiment of the present invention will be described in detail with reference to the drawings. (1) Overall Configuration of Apparatus FIG. 1 shows a schematic configuration of a textile printing apparatus as an example of an inkjet printer apparatus according to the present invention. In this figure, a cloth 1 is a recording medium (print medium), and is unwound according to the rotation of the unwind roller 11,
After being transported in a substantially horizontal direction by the transport unit 100 provided at a portion facing the printer unit 1000 via the printer unit 1000 and the printer unit 1000, it is taken up by the take-up roller 21 via the feed roller 17 and the intermediate roller 19.

The transport section 100 includes transport rollers 110 and 120 provided on the upstream and downstream sides of the printer section 1000 along the transport direction of the fabric 1, and an endless belt-shaped transport belt wound between the rollers. 130, and a pair of platen rollers 140 provided to improve the flatness by extending the transport belt 130 with a proper tension within a predetermined range to regulate the printing surface of the non-woven fabric flat when printing by the printer unit 1000. are doing. In this example, the transport belt 130 is made of a metal as disclosed in Japanese Patent Application Laid-Open No. H5-212851, and has an adhesive layer on its surface as shown partially enlarged in FIG. (Seat) 13
3 are provided. Then, the non-woven fabric 1 is a sticking roller 1
The adhesive layer 133 adheres to the transport belt 130 by the adhesive layer 50, and flatness during printing is secured.

The nonwoven fabric 1 conveyed in such a state where the flatness is ensured is supplied with a printing agent by the printer unit 1000 in an area between the platen rollers 140, and the conveyance belt 130 or The film is peeled off from the adhesive layer 133 and is wound up by the winding roller 21, and a drying process is performed by the drying heater 600 on the way. In addition, as the drying heater 600, an appropriate heater such as a heater that blows warm air onto the nonwoven fabric 1 and a heater that irradiates infrared rays can be used. (2) Configuration of Printer Unit FIG. 2 is a perspective view schematically showing a printer 1000 and a transport system for the non-woven fabric 1, and FIG. 3 is a sectional view showing a scanning system of the carriage. The configuration of the printer unit 1000 will be described with reference to FIGS.

In FIG. 1 and FIG.
No. 00 has a carriage 1010 that is scanned in a direction different from the transport direction (sub-scanning direction) F of the textile 1, for example, in the width direction S of the textile 1 orthogonal to the transport direction F. The support rail 1020 extends in the S direction (main scanning direction),
A slider 1012 fixed to the carriage 1010 is supported, and a slide rail 1022 for guiding is supported.
The motor 1030 is a driving source for performing main scanning of the carriage 1010, and its driving force is
Is transmitted to the carriage 1010 via the fixed belt 1032 and other appropriate transmission mechanisms.

The carriage 1010 moves the print head 1100 having a large number of printing agent applying elements in a predetermined direction (in this example, the transport direction F) in a direction different from the predetermined direction (the main scanning direction S in this example). , And in the present example, they are held in two stages in the transport direction. In the print head 1100 of each stage, the color used for the printing agent having a different color and the number of print heads can be conveniently selected according to the image to be formed on the non-woven fabric 1. It may be a certain yellow (Y), magenta (M), and cyan (C), or further a black (Bk). Alternatively, or in addition to these, it is possible to use a special color (metallic color such as gold or silver, vivid red or blue, etc.) that cannot be expressed or is difficult with the three primary colors. Alternatively, even in the case of the same color, a plurality of printing agents may be used according to the density.

In this embodiment, a plurality of print heads 1100 arranged in the main scanning direction S are provided in two stages in the transport direction F as shown in FIG. The color, the number, the arrangement order, and the like of the printing agents used by the print heads in each stage may be the same in each stage or may be different depending on the image to be printed. Further, it is also possible to print again the area printed by the main scan of the one-stage print head by the next-stage print head (or to perform complementary thinned-out printing by the respective-stage print heads). However, high-speed printing may be performed by sharing the printing area. Further, the number of print head stages is not limited to two, but may be one or three or more.

In this embodiment, the print head 1100
For example, an inkjet head, for example, a bubble jet head proposed by Canon Inc., having a heating element for generating thermal energy that causes film boiling of ink as energy used for discharging ink is used. Then, for the non-woven fabric 1 to be transported substantially horizontally by the transport unit 100, the ink ejection ports as the printing agent applying elements are used in a state where the ink ejection ports face downward, thereby eliminating the head difference between the respective ejection ports, The discharge conditions are made uniform to enable good image formation, and uniform recovery processing for all discharge ports is enabled.

In FIG. 3, capping means 1220
In the non-printing operation, the abutment is performed on the discharge port surface of each print head 1100 to suppress the drying and the intrusion of foreign matter, or to remove the foreign matter. Specifically, during a non-printing operation, the print head 1100 moves to a rest position facing the capping unit 1220. The capping unit 1220 is driven in the cap direction by the driving unit 1210 to perform capping by bringing an elastic member or the like into contact with the discharge port surface.

The clogging prevention means 1231 receives the discharged ink when the print head 1100 performs a discharge operation (preliminary discharge operation) for equalizing discharge conditions by ink refresh. The clogging prevention means 1231 is provided at a portion facing the print head outside the print area by the print head, and a liquid receiving member for absorbing and receiving the pre-discharged ink is provided between the capping means 1220 and the print area and between the capping means 1220 and the print area. It is located on the opposite side. Note that a liquid holding member is provided in the liquid receiving member, and a sponge-like porous member or the like is used as a material thereof.

A wiping means (wiping blade) 70 is provided between the capping means 1220 and the print area so as to rub the discharge port surface of the print head 1100. The wiping blade 70 adheres to the discharge port surface by the rubbing. Drops and dust boundaries are wiped out. (3) Configuration of Non-ejection Detection Unit FIGS. 4 and 5 show a schematic configuration of the detection unit of the non-ejection head according to the present invention. In FIG. 4, the print heads 2 and 2 'have a large number of nozzles on the lower surface, and discharge ink toward the clogging prevention means 1231 at the rest position.
The arrow 3 indicates the main scanning direction, and the carriage is moved by the belt 1032 in the main scanning direction. The fabric 1 as a print medium is sub-scanned in the direction of arrow 4. The shaded portion 8 'has already been printed, and the white background portion 8 "is to be printed.

In the rest position, as shown in FIG. 4, the beam 7 runs from the light emitting section 5 to the light receiving section 6 substantially in parallel with the nozzle arrangement, and a lens or the like is provided between the head 2 and the head 2 '. An optical system 9 is provided. FIG. 5 is a sectional view taken at the position of the beam 7, and FIG. 6 is an optical path diagram at that time. As shown in FIG. 5, the print heads 2 and 2 ′ are fixed at the position of the beam 7, and
As shown by B, C,..., Ink droplets are sequentially ejected from each nozzle at a certain fixed cycle, and after the detection of the head 2 is completed,
As shown by A ', B', C ',... From each nozzle of the next head 2', ink droplets are sequentially shot into the beam 7 at a certain fixed cycle. As shown in FIG. 6, the light is diffracted as it travels. Therefore, the light is condensed by the optical system 9 provided between the head 2 and the head 2 ′ at a position where the diffraction of the light is increased. Reduce the effect. As a result, even in a printer in which the light receiving element and the light emitting element are separated from each other, such as a case where two heads are arranged in the nozzle row direction, it is possible to reliably detect a non-ejection nozzle.

As shown in FIG. 11, the output voltage from the sensor 6 is plotted on the vertical axis, and the time is plotted on the horizontal axis, as shown in FIG. If the nozzle is a normal nozzle, the output of the sensor at the moment when the ink droplet passes through and blocks the light beam is delayed by a predetermined time from the timings t1, t2. If the timing ts
As described above, if there is a nozzle whose output voltage from the sensor does not change even if a predetermined time has elapsed from the ink ejection timing, it is determined that the nozzle has not ejected an ink droplet. This determination is made by a printer control unit (not shown). The printer control unit has a microprocessor and the like, and controls the entire printer device based on output of various sensors including an output signal from the light receiving unit 6 and a source of image data to be printed. Communicates with a host computer.

The non-discharge detected in this way is reported to a display panel (not shown) provided in the printer, a host computer for controlling the printer, and the like, and is reported to the operator.

As described above, in the ink jet printer of the present embodiment, the influence of light diffraction is reduced by providing an optical system between the heads, and the printer in which the light receiving element and the light emitting element are separated from each other. However, non-discharge can be detected reliably.

In this embodiment, when two heads are arranged in the nozzle row direction, first, the head is fixed at a certain detection position, and when the ink droplet is ejected from the nozzle of the head far from the light receiving element. When ink droplets are ejected from the nozzles of the head close to the above, there is a problem of light diffraction, so the amount of light sensed by the light receiving element differs. It has been proposed to provide non-discharge detection by providing ink between the two heads and sequentially discharging ink from the two heads.

However, as shown in FIG.
In addition, when three or more nozzles are arranged in the nozzle row direction, detection can be performed by providing an optical system between the heads.

[0026]

Other Embodiments In the first embodiment, it has been proposed to fix a head at a detection position and detect non-discharge. But,
As shown in FIG. 9, if the beam is run so as to have a certain angle with the direction of the nozzle row of the head, and the ink is ejected based on the encoder so that the ink falls therein, the ejection failure is detected while moving the head. Things become possible. That is, the ink is ejected while moving the head so that the light beam hits the ink droplet ejected from the nozzle which is the target of non-ejection detection, and the presence or absence of ejection is detected by a sensor output at that time. For this reason, a non-ejection nozzle can be detected while performing a printing operation.

The above-described embodiment is particularly provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink even in an ink jet recording system. By using a method in which a change in the state of the ink is caused by energy, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or the liquid path holding the Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of the liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600, which discloses a configuration in which a heat acting surface is arranged in a bent region, is also included in the present invention. In addition, for multiple electrothermal transducers,
JP-A-59-123670 which discloses a configuration in which a common slot is used as a discharge part of an electrothermal transducer, and JP-A-59-123670 which discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge part. A configuration based on 138461 may be adopted.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above-mentioned specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition to the cartridge type recording head in which the ink tank is provided integrally with the recording head itself described in the above embodiment, the recording head is electrically connected to the apparatus main body by being mounted on the apparatus main body. A replaceable chip-type recording head, which enables a simple connection and supply of ink from the apparatus main body, may be used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a single recording head or a combination of a plurality of recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture.

In the above-described embodiment, the description has been made on the assumption that the ink is a liquid. However, even if the ink solidifies at room temperature or lower, the ink that softens or liquefies at room temperature is used. Or, in the ink jet method, generally, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range.
It is sufficient that the ink is in a liquid state when the use recording signal is applied.

In addition, in order to positively prevent the temperature rise due to thermal energy as energy for changing the state of the ink from the solid state to the liquid state,
Alternatively, in order to prevent evaporation of the ink, an ink which solidifies in a standing state and liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start to solidify when reaching the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held in a liquid state or a solid state in the concave portion or through hole of the porous sheet. It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition to the above, the recording apparatus according to the present invention may be provided not only as an image output terminal of an information processing apparatus such as a computer but also integrally or separately, a copying apparatus combined with a reader or the like, and a transmission / reception apparatus. It may take the form of a facsimile machine having functions.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copier, a facsimile). Device).

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to provide a computer (or CPU) of the system or apparatus.
Or MPU) reads and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) Performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, The case where the CPU of the function expansion board or the function expansion unit performs part or all of the actual processing, and the function of the above-described embodiment is realized by the processing.

[0044]

As described above, according to the present invention,
By providing an optical system between the head and the head where the nozzle does not discharge due to the diffraction of the beam by the optical system provided on the beam path, two or more heads are arranged in the nozzle row direction, and the light emitting element and the light receiving element Even in a system where the distance is long, it is possible to reliably detect whether or not ink droplets have been ejected to all nozzles.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a textile printing apparatus which is an embodiment of an ink jet printing apparatus according to the present invention.

FIG. 2 is a perspective view of a printing unit of the apparatus shown in FIG.

FIG. 3 is a side sectional view of the print unit shown in FIG. 2;

FIG. 4 is a perspective view illustrating a configuration of a non-discharge detection unit in the textile printing apparatus according to the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of a non-discharge detection unit in the textile printing apparatus according to the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a non-discharge detection unit in the textile printing apparatus according to the present invention.

FIG. FIG. 4 is a cross-sectional view of an experimental apparatus for examining the relationship between the nozzle position and the ease of detecting non-ejection of a light receiving element.

FIG. 8 is a graph showing the relationship between the nozzle position and the ease of detecting non-ejection of a light receiving element.

FIG. 9 is a plan view illustrating a configuration of a non-ejection detection unit according to another embodiment.

FIG. 10 is a cross-sectional view illustrating a configuration of a non-discharge detection unit for a printer having three or more heads.

FIG. 11 is a graph showing a transition of an output from a light receiving unit when a non-ejection is detected.

Claims (7)

[Claims] 1. A head unit for discharging ink droplets from discharge ports arranged in series, a light emitting unit for emitting a light beam so as to pass the ink droplets discharged from the head unit, and a light emitting unit for emitting the light beam. A non-discharge detection unit that receives a light and outputs a signal corresponding to the intensity thereof, and a non-discharge detection unit that has at least one optical system between the light emitting unit and the light receiving unit and that condenses a light beam. Inkjet printer device. 2. The ink jet printer according to claim 1, further comprising a determination unit configured to sequentially discharge ink droplets from each of the discharge ports of the head unit and determine a non-discharge discharge port based on an output signal from the light receiving unit. Item 2. An ink jet printer according to item 1. 3. The ink jet printer according to claim 1, further comprising: a determination unit configured to sequentially discharge ink droplets from each of the discharge ports of the head unit and determine a non-discharge discharge port based on an output signal from the light receiving unit. Item 2. An ink jet printer according to item 1. 4. The ink-jet printer according to claim 1, wherein the optical system is located between the discharge ports arranged adjacent to each other and arranged in series. 5. The method according to claim 1, wherein the light beam is emitted along a direction in which the ejection ports of the head unit are arranged, and the determination unit detects the non-ejection by fixing the head on the light beam. The inkjet printer device according to claim 2, wherein 6. The light beam is emitted in a direction at a predetermined angle with respect to the direction in which the ejection ports of the head unit are arranged, and the determination unit moves the head unit so that ink droplets hit the light beam. The ink jet printer device according to claim 2, wherein a misstep ejection is detected. 7. The ink jet printer according to claim 1, wherein the head unit has a heater for heating the ink for each discharge port, and the heater applies heat to the ink to discharge the ink. Printer device.