JPH11192726A - Method and apparatus for image forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To comparatively accurately grasp that a residual quantity of a liquid reserved in a liquid reserving tank becomes small by a method wherein a tank weight detecting means is provided in a scanning range of a carriage and the weight of the liquid reserving tank is directly detected. SOLUTION: This image forming apparatus comprises a carriage 15 that accommodates a liquid ejection head for performing printing on a printing medium 21 by ejecting a liquid from an ejection nozzle and a liquid reserving tank 20T for reserving a liquid to be supplied to the liquid ejection head and can be scanned in a predetermined range. A tank weight detecting means 34 for detecting a weight of the liquid reserving tank 20T and a liquid ejection detecting means 35 for optically detecting an ejecting condition that a liquid is ejected from the nozzle are provided in a portion in a scanning range of the carriage 15. A weight of the liquid reserving tank 20T mounted on the carriage 15 is detected. When the detected weight is lower than a predetermined level, a liquid is ejected from the nozzle and the ejection condition is optically detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head by scanning and moving a carriage on which a liquid discharge head for discharging liquid from a discharge port and a liquid storage tank for storing liquid supplied to the liquid discharge head are mounted. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for printing on a medium and an apparatus therefor, and more particularly, to a method for accurately grasping the remaining amount of liquid stored in a liquid storage tank.

[0002]

2. Description of the Related Art An ink or a liquid such as a processing liquid for adjusting the printability of the ink is ejected from an ejection port of an ink jet head, and a desired image is formed on a print medium such as paper, a resin film, or a cloth or metal. The inkjet printer that forms the ink jet printer is excellent in quietness, printing speed is high, high-density printing is possible, and colorization is easy because the inkjet head is not in contact with such a printing medium. Advantages such as miniaturization of the whole can be obtained.

[0003] As one of such ink jet printers, a liquid discharge head for discharging liquid from a discharge port,
There is known a so-called serial type in which a carriage on which a liquid storage tank for storing the liquid supplied to the liquid discharge head is mounted is moved by scanning to print on a print medium.

In such a serial type ink jet printer, it is necessary to accurately grasp the remaining amount of the liquid in the liquid storage tank and to prevent the liquid from running out during the printing operation. The ejection state is detected optically, or as described in JP-A-1-120352, the number of ejection dots of the liquid from the ejection port and the number of the ejection of the liquid from the ejection port of the inkjet head are described. The remaining amount of the liquid in the liquid storage tank is predicted based on the accumulation of the liquid consumption amount by the recovery processing for making the ejection state appropriate. In addition, a pair of electrodes are provided in the liquid storage tank to detect the remaining amount of the liquid in the liquid storage tank using the conductivity of the liquid, or according to the remaining amount of the liquid in the liquid storage tank. A method of detecting a mechanical displacement is also known.

[0005]

SUMMARY OF THE INVENTION In a serial type ink jet printer, the state of discharge of liquid from an ink jet head is optically detected, whereby
In the conventional method for predicting the remaining amount of liquid in the liquid storage tank, even immediately after refilling the liquid in the liquid storage tank or immediately after replacing the liquid with a new liquid storage tank,
It is necessary to discharge the liquid from the inkjet head every time the remaining amount is predicted. As a result, the amount of liquid consumed without printing increases, and it becomes necessary to frequently replenish the liquid storage tank or replace the liquid storage tank with a new one. However, there is a disadvantage that the amount of print media that can be printed becomes small and the amount of print media that can be printed is reduced.

In addition, the accumulation of the number of times the liquid is ejected from the ejection port and the amount of liquid consumed by the recovery process for optimizing the ejection state of the liquid from the ejection port of the ink jet head is performed. According to the conventional method of estimating the remaining amount of liquid, when it is necessary to replace a liquid storage tank in use with another liquid storage tank for some reason, the storage amount of liquid stored up to that point is calculated. In the worst case, the replaced liquid storage tank may not be able to determine how much liquid is stored in the replaced liquid storage tank. Even if it ’s new,
This may lead to a prediction that the remaining amount of liquid is low.

Further, in a conventional method in which a pair of electrodes are provided in a liquid storage tank and the remaining amount of the liquid in the liquid storage tank is detected by utilizing the conductivity of the liquid, the deterioration of the liquid is performed by applying a current. The conventional method of detecting mechanical displacement according to the remaining amount of liquid in the liquid storage tank is not reliable because of the possibility of causing There were inconveniences such as an increase in manufacturing cost.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to minimize the amount of liquid ejected from a liquid ejection head in order to ascertain the remaining amount of liquid in a liquid storage tank, to provide a highly reliable and low-cost liquid storage tank. It is an object of the present invention to provide an image forming method and apparatus capable of accurately grasping the remaining amount of liquid.

[0009]

According to a first aspect of the present invention, there is provided:
An image forming method for performing printing on a print medium by scanning and moving a carriage on which a liquid discharge head that discharges liquid from a discharge port and a liquid storage tank that stores liquid supplied to the liquid discharge head is mounted. Detecting the weight of the liquid storage tank mounted on the carriage, and, if the detected weight of the liquid storage tank is smaller than a predetermined weight, discharging the liquid from the discharge port to optically change the discharge state. And a step of dynamically detecting.

According to the present invention, the step of discharging the liquid from the discharge port and optically detecting the discharge state is performed only when the weight of the liquid storage tank mounted on the carriage is smaller than a predetermined weight, The consumption of the liquid mounted on the liquid storage tank is suppressed.

According to a second aspect of the present invention, there is provided a liquid discharge head for discharging a liquid from a discharge port to perform printing on a print medium, and a liquid storage tank for storing the liquid supplied to the liquid discharge head. An image forming apparatus having a carriage mounted thereon and capable of scanning and moving within a predetermined range, wherein tank weight detecting means for detecting the weight of the liquid storage tank, and optically detecting a state of discharging the liquid from the discharge port. And a liquid discharge detecting means for detecting the liquid discharge within a scanning range of the carriage.

According to the present invention, the remaining amount of the liquid stored therein is estimated by detecting the weight of the liquid storage tank mounted on the carriage by the tank weight detecting means. Further, the ejection state of the liquid ejected from the ejection port of the liquid ejection head is optically detected by the liquid ejection detection means, and when the liquid is not ejected from the ejection port, the liquid is stored in the liquid storage tank. It is estimated that the liquid storage tank is not mounted on the carriage, or that the discharge port of the liquid discharge head is clogged.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The image forming method according to the first aspect of the present invention further comprises the step of, if the detected liquid ejection state is not appropriate, adjusting the liquid ejection state from the ejection port. You may do it. Further, when the liquid storage tank is mounted on the carriage, the method may further include a step of sucking the liquid from the discharge port prior to a step of detecting a weight of the liquid storage tank. Further, the liquid may be ink for printing on a print medium or a processing liquid for adjusting printability of the ink on the print medium.

In the image forming apparatus according to the second aspect of the present invention, the image forming apparatus further includes a recovery processing unit for optimizing a discharge state of the liquid from the discharge port, and the discharge port detected by the liquid discharge detection unit. When the ejection state of the liquid from the ejection port is not appropriate, the ejection state of the liquid from the ejection port may be adjusted by the recovery processing unit. In this case, the recovery processing means may further include a capping member that covers a discharge port surface of the liquid discharge head where the discharge port opens, and sucks liquid from the discharge port via the capping member. Is preferred.
Further, the liquid storage tank may be exchangeably mounted on the carriage. Further, the liquid discharge head may include a discharge energy generation unit for discharging liquid from the discharge port, and in this case, the discharge energy generation unit may include an electrothermal converter that generates heat energy. It is preferable to have

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the image forming apparatus according to the present invention is applied to an ink jet printer will be described in detail with reference to FIGS. 1 to 9. However, the present invention is not limited to such an embodiment, but has the same problems. It can also be applied to technologies in other fields that include.

FIG. 1 shows an external appearance of the ink jet printer according to the embodiment in a broken state, and FIG. 2 shows a schematic structure of a main part thereof in a broken state. That is, the endless belt 13 wound around the motor pulley 11 and the tension pulley 12 is turned and moved by the carriage drive motor 14, so that the carriage 15 connected to the endless belt 13 is moved to the left and right side plates 16, It scans and moves left and right while being guided by a guide shaft 18 spanned between 17. An ink jet cartridge 20 is exchangeably mounted on the carriage 15 via a cartridge holder 19. Inkjet cartridge 20 includes an ink tank portion 20 _T which ink is reservoir, the ink jet head portion 20 _H for ejecting reservoir ink in the ink tank portion 20 _T.

The ink-jet cartridge 20 is moved with the carriage 15 in a direction perpendicular to the plane of FIG.
While the ink is ejected from an ejection port (not shown) of _H , a print medium 21 such as paper is fed to a platen roller shaft by a platen roller 23 and a medium guide 24 driven by a medium transport motor 22 and a plurality of pairs of pinch rollers 25 and 26. 27 is revolving conveyor counterclockwise along the outer peripheral surface of the platen roller 23 around a print operation is performed just below the ink jet head portion 20 _H. 28 is
An electrical contact portion provided in the carriage 15, the ink ejection signal as a drive signal to the electrothermal transducer (not shown) of the ink jet head portion 20 _H is provided via the electrical contacts 28. Reference numeral 29 denotes a light transmission type home position sensor for indexing the carriage 15 to the standby position shown in FIGS. 1 and 4. Reference numeral 30 denotes a dog provided on the carriage 15 corresponding to the home position sensor 29.

The carriage 15 is rotatably supported on the guide shaft 18 as shown in FIG. 2, and a slider 31 projecting downward from the carriage 15 comes into sliding contact with a paper pressing plate 32. it allows in FIG. 2 of the carriage 15, it is prevented from counterclockwise rotation about the guide shaft 18, and the ink jet head portion 20 _H and the print medium 21 of the ink jet cartridge 20 is defined at predetermined intervals.

The carriage 15 has a projection 3 for weight detection.
The weight sensor 3 is provided on one side plate 16 as a weight detecting means positioned on the movement locus of the protrusion 33.
4 are provided, and when the projection 33 is located on the weight sensor 34, the projection 33 rides on the weight sensor 34 as shown in FIG. The facing portion between the protrusion 33 and the weight sensor 34 is formed in an inverted trapezoidal shape and a chevron shape having a gentle slope that is symmetrical in the operating direction of the carriage 15 so that the protrusion 33 can ride on smoothly. It has become. As the weight sensor 34, various load cells and the like can be used. FIG.
In this embodiment, the weight detection position of the weight sensor 34 is set outside the print scanning area for the print medium 21 and within the scanning range of the carriage 15, and one of the scanning positions of the inkjet cartridge 20 shown in FIGS. It is located at the standby position set at the moving end, that is, between the home position and the print scanning area for the print medium 21.

Therefore, as shown by the two-dot chain line in FIG.
The carriage 15 moves, and the protrusion 33 moves to the weight sensor 34.
By riding up, the slider 31 separates from the paper pressing plate 32, and the weight of the carriage 15 including the ink jet cartridge 20 (turning moment about the guide shaft 18) can be detected. This weight sensor 3
Weight detected by 4, so decreases with the consumption of ink in the ink tank portion 20 _T of the ink jet cartridge 20, the carriage 15 of the unused state to be mounted on the ink jet cartridge 20 and the ink tank unit 20 _T If the weight of the ink is known in advance, the ink tank unit 20 is calculated from the detected weight.
The remaining amount of ink in _T can be detected. That is,
The weight sensor 34, a substantially ink tank unit 2 corresponding to the amount of ink accommodated in the ink tank portion 20 _T
A weight of 0 _T will be detected directly.

[0021] Here, ink jet "Substantial ink weight" of the ink tank unit 20 _T, which integrates the weight of only the ink tank unit 20 _T, or the ink tank portion 20 _T and the ink jet head portion 20 _H Including the weight of the cartridge 20 or the weight to which the carriage 15 is further added, it is most preferable to directly detect the weight of the ink tank section _20T . The projection 33 rides on the weight sensor 34 outside the print scanning area of the carriage 15 for the printing operation.
Does not hinder the print scan of.

FIG. 3 shows a photo-interrupter 35 serving as a liquid discharge detecting means in an extracted and enlarged view. That is, 36 is a light emitting side element that projects a light beam 37 for detection,
Reference numeral 38 denotes a light receiving side element, which is arranged at an ink ejection detection position set at the other scanning movement end of the carriage 15 set outside the print scanning area for the print medium 21. The carriage 15 is located at the ink ejection detection position shown in FIG.
There moves, ink droplets are discharged from the discharge port of the ink jet head portion 20 _H, whereby the light beam 37 is blocked, ink droplets from the discharge ports of the ink jet head portion 20 _H occurs a change in output of the light-receiving side device 38 can be detected that the discharged, detecting a conversely, the change in the output of the light-receiving side device 38 is in the case of not occurred, the ink droplets from the discharge ports of the ink jet head portion 20 _H has not been discharged can do.

[0023] In this embodiment, the carriage 15 to the ink discharge detection position which is the other of the scanning movement end of the carriage 15 is stopped, to sense the discharge state of ink from the discharge ports of the ink jet head portion 20 _H in this state However, the detection may be performed during the scanning movement of the carriage 15.

FIG. 7 shows an example of the operation procedure of such an ink jet printer. That is, before the print signal is output, the ejection port surface 39 where the ejection port of the ink jet cartridge 20 is open is waiting at the standby position while being covered by a capping member (not shown), and is at the position shown in FIG. .

Here, when a print signal is issued in step S11, the carriage 15 starts to scan and move from the standby position to the side of the tank weight detection position, and the tank weight detection where the weight sensor 34 is disposed. Stop at the position. Here, as shown in FIG. 5, the carriage 15 rides on the weight sensor 34 and detects the weight of the carriage 15.

[0026] Then, based on the detection signal from the determination unit weight sensor 34 (not shown), whether preset determination reference weight W weight W _n that is actually detected than _R is small in step S12 judge. If it is determined that the weight W _n that is actually detected than the determination reference weight W _R at this step S12 is small, that is the remaining amount of ink in the ink tank portion 20 _T shifts to S13 in step a slight A warning is output, for example, a warning light (not shown) is turned on. Then, in step S14, the carriage 15 moves along the platen roller 23 to the photo interrupter 35 at the ink ejection detection position. Therefore, ink is discharged from the discharge ports of the ink jet head portion 20 _H, it is actually determined by the determination unit (not shown) on the basis of whether the ink is discharged to a detection signal from the photo-interrupter 35.

[0027] If it is determined that the ink at this step S14 is actually ejected from the inkjet head unit 20 _H, the process proceeds to step S15 carriage 1
5 is moved to the print start position, and the printing operation on the print medium 21 is started. Further, the ink is not ejected from the ink jet head portion 20 _H at step S14, i.e. ink when it is determined that there is no ink in the tank portion 20 _T, the ink tank unit 20 proceeds to S16 in step _T Is output, for example, a warning light (not shown) is blinked.

On the other hand, it is actually detected weight W _n is the determination reference weight W _R or determined in step S12, that is, when the remaining amount of ink in the ink tank portion 20 _T is determined to sufficiently certain, at S15 Move to step and carriage 1
5 moves to the print start position, and the printing operation on the print medium 21 is started.

[0029] Thus, with the occurrence of the print signal to detect the remaining amount of ink in the ink tank unit 20 _T, ejection of ink from the ink jet head portion 20 _H only if it is determined that the remaining amount is insignificant since so as to detect the state, the remaining amount of ink in the ink tank portion 20 _T becomes insignificant and can warn appropriate that it no longer. In addition, the amount of ink consumed other than for printing can be reduced, and the number of print media 21 that can be printed can be increased.

[0030] In the embodiment shown in FIG. 7, when the ink runs out the ink tank unit 20 _T, but so as to replenish the ink in the ink tank portion 20 _T without replacing the inkjet cartridge 20, inkjet cartridge It is also possible to cope by exchanging 20.

When replacing the ink jet cartridge 20, a key (not shown) is first pressed to move the carriage 15 to a substantially central portion of the scanning range. in this case,
Inkjet head _20H and ink tank _20T
When is an integral inkjet cartridge 20,
The entire ink jet cartridge 20 is replaced.
In terms of running cost, the ink tank 20
_T and the ink jet head portion 20 _H has become a removable, it is often to replace only the ink tank unit 20 _T. Therefore, it may happen that would leave the user has removed the ink tank portion 20 _T from the ink jet head unit 20 _H. When the ink tank unit 20 _T is left not installed, ink adhered to the connecting portion ends up drying of the ink jet head portion 20 _H and the ink tank portion 20 _T, causing problems such as sticking and thickening Printing may not be possible.

The above To avoid problems, a predetermined amount from the discharge ports of the ink jet head portion 20 _H by a suction device (not shown) through the capping member immediately after replacing the ink jet cartridge 20 (at least the ink jet head portion 20 _H internal volume of It is preferable to aspirate the ink of (i).

FIG. 8 shows an operation procedure of another embodiment of the present invention in view of such knowledge. That is, when replacement of the ink jet cartridge 20 has been performed, recovery processing for sucking ink from the discharge ports of the ink jet head portion 20 _H is performed in S21 in step, then the weight of the ink tank portion 20 _T at S22 in step detects, determines whether the actually detected weight W _n than the determination reference weight W _R that is set in advance is small. Weight W _n that is actually detected than the determination reference weight W _R at this step S12
Is smaller, the process proceeds to step S23, where the ink jet cartridge 20 is moved to the ink tank section _20T.
It is determined whether or not it is of the exchange type only.

[0034] When the ink jet cartridge 20 is determined to be that only the replaceable ink tank unit 20 _T is at this S23 in step, the ink from the discharge ports of the ink jet head portion 20 _H and proceeds to step S24, The ink is ejected, and whether or not the ink is actually ejected is determined by a determination unit (not shown) based on a detection signal from the photo interrupter 35.

[0035] If it is determined that the ink in the step S24, is actually ejected from the inkjet head unit 20 _H, waits for the output of the print signal proceeds to step S25. Conversely, the ink is not ejected from the ink jet head portion 20 _H in S24 in step, that is, if it is determined that there is no ink in the ink tank unit 20 _T, the ink tank unit proceeds to step S26 20 Outputs a warning that ink needs to be added to _T ,
For example, a warning light (not shown) blinks. This warning, the ink tank unit 20 _T is also a warning that it is not mounted on the carriage 15.

[0036] If the ink jet cartridge 20 is determined in step S23 is not intended only replaceable ink tank unit 20 _T, i.e. an ink tank portion 20 _T and the ink jet head portion 20 _H is determined to be the ink jet cartridge 20 of the integral , the weight W _n that have already been detected in S22 in step is determined to be smaller than the determination reference weight W _R, is insignificant amount of ink remaining in the transition to the ink tank section 20 _T to step S27 Then, a warning is output, for example, a warning light (not shown) is turned on. It is determined on the basis of the detection signal of the ink is discharged from the discharge ports of the ink jet head portion 20 _H, actually whether ink is discharged from the photo-interrupter 35 at S28 in step.

[0037] When the ink in S28 in step is determined to be actually discharged from the ink jet head unit 20 _H, waits for the output of the print signal proceeds to step S25. Conversely, the ink is not ejected from the ink jet head portion 20 _H in S28 in step, that is, if it is determined that there is no ink in the ink tank unit 20 _T, the ink tank unit proceeds to step S29 20
_A warning indicating that ink needs to be refilled at _T is output, for example, a warning light (not shown) blinks.

On the other hand, it is actually detected weight W _n is the determination reference weight W _R or at S22 in step, i.e. the carriage 15 the ink tank portion 20 _T is mounted to, yet the ink tank unit 20 _T If it is determined that the remaining amount of the ink is sufficient, the flow shifts to step S25 to wait for the output of the print signal.

[0039] Thus, after the discharge recovery processing of the ink jet head portion 20 _H prior to the printing operation,
Detecting the weight of the ink tank portion 20 _T, whether the actual weight W _n was detected is determined to lighter than the determination reference weight W _R, the ejection of ink from the ink jet head portion 20 _H has been performed normally since so as to determine, in a replaceable ink jet cartridge 20 independently of the ink tank portion 20 _T with respect to the ink jet head portion 20 _H, even when the ink tank unit 20 _T is not mounted, the ink tank unit 20 _T can be grasped state is not expected (replacement warning of the ink tank portion 20 _T). Further, after performing a recovery operation to prevent factors clogging of the discharge ports due to sticking and thickening of the ink to detect the weight of the ink tank portion 20 _T, further ejection of ink from the ink jet head portion 20 _H Since the state is detected, it is possible to prevent problems such as sticking and thickening of the ink.

In the above-described embodiment, the ejection recovery process is performed before the printing operation. However, the ejection recovery process may be performed only when clogging of the ejection port is expected.

FIG. 9 shows an operation procedure of another embodiment of the present invention. That is, when the print signal is generated in S31 step, the weight of the ink tank portion 20 _T is detected in step S32, actually is detected weight W _n than the determination reference weight W _R that is set in advance It is determined whether it is small.

In the step S32, the reference weight W is determined.
If it is determined that the weight W _n that is actually detected than _R is small, the ink tank unit proceeds to step S33 20 _T
A warning is output to the effect that the remaining amount of ink in the battery is low, for example, a warning light (not shown) is turned on. It is determined at S34 in step ink is discharged from the discharge ports of the ink jet head portion 20 _H, actually the determining means on the basis of whether the ink is discharged to a detection signal from the photo-interrupter 35.

[0043] When the ink in the S34 in step is determined to be actually discharged from the ink jet head unit 20 _H, i.e. an ink tank unit printable ink still in the 20 _T, the process proceeds to step S35 Then, the carriage 15 is moved to the print start position, and the printing operation on the print medium 21 is started. Also, S
In the step 34, the ink is supplied to the ink jet head 2
0 is not ejected from _H, i.e. an ink tank portion 20
If it is determined that there is no ink in _T , the process proceeds to step S36 to output a warning indicating that the ink jet cartridge 20 needs to be replaced, for example, to flash a warning light (not shown).

[0044] If it is determined that the actually detected weight W _n is the determination reference weight W _R or determined in step S32, that is, the remaining amount of ink in the ink tank portion 20 _T is sufficient, S37 ink proceeds to step detects the ejection state of the ink from the ink jet head unit 20 _H.

The ink in this S34 in step is actually ejected from the inkjet head unit 20 _H, that is, when the discharge ports of the ink jet head portion 20 _H is determined not to be clogged, the S35 in step Then, the carriage 15 is moved to the print start position,
The printing operation on the print medium 21 is started. Further, the ink is not ejected from the ink jet head portion 20 _H in S34 in step, that is, if the discharge ports of the ink jet head portion 20 _H is determined to be clogged, the process proceeds to S38 in Step inkjet after ink is sucked from the head portion 20 _H outlet of, perform the discharge recovery process for removing the cause of the nonprintable such as air in the ink and the ejection mouth fixed to the discharge port, S
At step 35, the printing operation on the print medium 21 is started.

This eliminates the need to perform the discharge recovery processing at predetermined time intervals by the timer, which has been conventionally performed.
The load on the CPU that controls the operation of the ink jet printer is reduced, so that it is possible to suppress a decrease in printing speed, and it is possible to reduce the amount of ink discharged by the ejection recovery processing.

The present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging the liquid, and the state of the liquid is controlled by the thermal energy. The present invention brings about an excellent effect in an ink jet type liquid ejection head, a head cartridge, or an image forming apparatus which causes a change. According to such a method, it is possible to achieve higher density and higher definition of the print.

The typical configuration and principle are described in, for example, US Pat. No. 4,723,129 and US Pat.
It is preferable to use the basic principle disclosed in Japanese Patent Application No. 0796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the flow path holding the liquid. Heat energy is generated by applying at least one drive signal to the electrothermal transducer to give a rapid temperature rise exceeding nucleate boiling corresponding to print information, thereby causing film boiling on the heat working surface of the liquid discharge head. As a result, bubbles in the liquid corresponding to this drive signal one-to-one can be formed, which is effective. By the growth and shrinkage of the bubble, the liquid is discharged through the discharge port to form at least one droplet. 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 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. If the conditions described in U.S. Pat. No. 4,313,124 relating to the rate of temperature rise of the heat acting surface are adopted, more excellent printing can be performed.

The structure of the liquid discharge head is a combination of a discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications (the electrothermal converter is arranged along the liquid path). U.S. Pat. No. 6,059,055 discloses a configuration in which a disposed linear liquid flow path or an electrothermal converter is disposed in a region where a heat acting portion is bent in addition to a liquid flow path and a right-angled liquid flow path directly facing the discharge port. Patent No. 4558333 and US Patent No. 44596
The configuration using the specification of No. 00 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal transducer for a plurality of electrothermal transducers, and an aperture for absorbing a pressure wave of thermal energy is provided. The effects of the present invention are effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to the ejection unit. That is, according to the present invention, printing can be performed reliably and efficiently regardless of the form of the liquid discharge head.

Further, even in the case of the serial type as described above, the liquid discharge head integrally fixed to the carriage that moves and scans, or the liquid discharge head that is exchangeably mounted on the carriage, allows electrical connection with the carriage. When using a replaceable chip-type liquid ejection head that allows for a flexible connection and supply of liquid from the apparatus body, or when using a head cartridge that has a tank that stores liquid integrally with the liquid ejection head itself, The present invention is effective.

Further, as a configuration of the image forming apparatus of the present invention, adding recovery means for making the state of liquid discharge from the liquid discharge head proper, preliminary auxiliary means, and the like add the effects of the present invention. This is preferable because it can be further stabilized. Specific examples thereof include a capping unit for the liquid ejection head, a cleaning unit, a pressurizing or suctioning unit, a preheating unit for heating using an electrothermal transducer, another heating element, or a combination thereof. And a preliminary ejection unit for performing ejection other than printing.

The type and number of liquid ejection heads to be mounted also correspond to a plurality of inks having different print colors and densities, for example, in addition to a single ink provided for only one color. May be provided in plurality. That is, for example, the print mode of the image forming apparatus is not limited to a print mode of only a mainstream color such as black, and may be either an integrated liquid discharge head or a combination of a plurality of liquid discharge heads. The present invention is extremely effective also in an apparatus provided with at least one of the print modes of full-color by color or mixed color. In this case, it is also effective to discharge the processing liquid (printability improving liquid) for adjusting the printability of the ink according to the print medium from the dedicated liquid discharge head to the print medium.

In addition, in the embodiment of the present invention described above, a material which solidifies at or below room temperature and softens or liquefies at room temperature may be used. In general, the temperature is controlled within the range of not more than ° C. and the temperature is controlled so that the viscosity of the liquid is in a stable ejection range. In addition, in order to positively prevent the temperature rise due to thermal energy by using it as the energy of the state change from the solid state to the liquid state, or to prevent the liquid from evaporating, it is solidified in a standing state and liquefied by heating. May be used. In any case, the liquid is liquefied by the application of the heat energy according to the print signal, and is liquefied only by the application of the heat energy, such as the one from which the liquid is discharged and the one which already starts solidifying when reaching the print medium. The present invention can be applied to the case of using a material having a property. The liquid in such a case is, as described in JP-A-54-56847 or JP-A-60-71260, in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. Alternatively, it may be configured to face the electrothermal converter. In the present invention, the most effective one for each of the above-mentioned liquids is to execute the above-mentioned film boiling method.

In addition to the above, the image forming apparatus according to the present invention may be used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader, or a facsimile having a transmission / reception function. It may be an apparatus or a textile printing apparatus.

[0055]

According to the present invention, the tank weight detecting means is provided within the scanning range of the carriage, and the weight of the liquid storage tank mounted on the carriage is directly detected. Even so, it can be relatively accurately grasped that the remaining amount of the liquid stored in the liquid storage tank has become small.

In addition, when the remaining amount of the liquid becomes small, the non-discharge state of the liquid from the liquid discharge head can be accurately grasped by the liquid discharge detection means provided within the operation range of the carriage. In addition, it is possible to appropriately set the replacement timing of the liquid storage tank and the discharge recovery timing for the discharge port of the liquid discharge head. In this case, since the liquid ejection detecting means is not used until the remaining amount of the liquid in the liquid storage tank becomes small, the amount of liquid used except during the printing operation can be suppressed, and the printable print can be performed. It is possible to increase the amount of medium.

In the case where the liquid is sucked from the liquid discharge head after the replacement operation of the liquid discharge head or the liquid storage tank mounted on the carriage, the tank weight detecting means is operated, and further the liquid discharge detecting means is operated. Even if the user forgets to attach the liquid storage tank to the carriage, this state can be reliably grasped. Moreover,
It is possible to avoid troubles such as sticking and thickening of the liquid at the connection between the liquid storage tank and the liquid discharge head.

[Brief description of the drawings]

FIG. 1 is a cutaway perspective view showing a schematic structure of an embodiment in which an image forming apparatus according to the present invention is applied to an ink jet printer.

FIG. 2 is a cutaway sectional view showing the structure of a main part of the embodiment shown in FIG.

FIG. 3 is a perspective view showing an appearance of a liquid ejection detection unit in the embodiment shown in FIGS. 1 and 2.

FIG. 4 is a conceptual diagram showing a scanning movement state of a carriage together with FIGS. 5 and 6, and shows a state at a standby position.

FIG. 5 is a conceptual diagram showing a scanning movement state of a carriage together with FIGS. 4 and 6, showing a state at a weight detection position.

FIG. 6 is a conceptual diagram showing a scanning movement state of a carriage together with FIGS. 4 and 5, showing a state at a liquid ejection detection position.

FIG. 7 is a flowchart illustrating an example of a work flow at the time of a print operation using the inkjet printer of the embodiment illustrated in FIGS. 1 to 6;

FIG. 8 is a flowchart showing an example of a work flow according to the embodiment shown in FIGS.

FIG. 9 is a flowchart showing another embodiment of a work flow at the time of a printing operation using the ink jet printer of the embodiment shown in FIGS.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Motor pulley 12 Tension pulley 13 Endless belt 14 Carriage drive motor 15 Carriage 16, 17 Side plate 18 Guide shaft 19 Cartridge holder 20 Inkjet cartridge 20 _T Ink tank part 20 _H Inkjet head part 21 Print medium 22 Media transport motor 23 Platen roller 24 Media guide Reference numerals 25, 26 Pinch roller 27 Platen roller shaft 28 Electric contact part 29 Home position sensor 30 Dog 31 Slider 32 Paper press plate 33 Projection 34 Weight sensor 35 Photo interrupter 36 Light emitting element 37 Light flux 38 Light receiving element 39 Discharge port surface

Claims (10)

[Claims] An image to be printed on a print medium by scanning and moving a carriage on which a liquid discharge head for discharging liquid from a discharge port and a liquid storage tank for storing liquid supplied to the liquid discharge head are mounted. Detecting the weight of the liquid storage tank mounted on the carriage, and discharging the liquid from the discharge port when the detected weight of the liquid storage tank is smaller than a predetermined weight. Optically detecting the ejection state. 2. The image forming method according to claim 1, further comprising the step of, if the detected liquid ejection state is not appropriate, adjusting the liquid ejection state from the ejection port. 3. When the liquid storage tank is mounted on the carriage, the method further comprises a step of sucking liquid from the discharge port, and this step is performed prior to the step of detecting the weight of the liquid storage tank. 2. The method according to claim 1, wherein
Alternatively, the image forming method according to claim 2. 4. The liquid according to claim 1, wherein the liquid is ink for printing on a print medium or a processing liquid for adjusting printability of the ink on the print medium. 2. The image forming method according to 1., 5. A liquid discharge head for discharging a liquid from a discharge port to perform printing on a print medium, and a liquid storage tank for storing a liquid supplied to the liquid discharge head are mounted to scan a predetermined range. An image forming apparatus having a movable carriage, comprising: a tank weight detection unit that detects a weight of the liquid storage tank; and a liquid discharge detection unit that optically detects a discharge state of a liquid from the discharge port. An image forming apparatus provided within a scanning range of a carriage. 6. A liquid ejection apparatus according to claim 1, further comprising a recovery processing unit configured to adjust a discharge state of the liquid from the discharge port to an appropriate state, wherein the liquid discharge state detected by the liquid discharge detection unit is not appropriate. The image forming apparatus according to claim 5, wherein the recovery processing unit optimizes a state of discharging the liquid from the discharge port. 7. The recovery processing means further includes a capping member that covers a discharge port surface of the liquid discharge head where the discharge port is opened, and sucks liquid from the discharge port via the capping member. The image forming apparatus according to claim 6, wherein: 8. The image forming apparatus according to claim 5, wherein the liquid storage tank is exchangeably mounted on the carriage. 9. The image forming apparatus according to claim 5, wherein the liquid discharge head has a discharge energy generating unit for discharging a liquid from the discharge port. 10. The image forming apparatus according to claim 9, wherein the discharge energy generation section has an electrothermal converter that generates heat energy.