JPH10114084A - Image forming apparatus and print head used in apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform quantities of printing continuously at a high speed by installing a liquid supply means which supplies liquid in a liquid tank at a liquid supply position on one end side in the scanning movement direction of a carriage. SOLUTION: A guide rod 13 is engaged with a carriage 14, a print head having a liquid holding part 18 is mounted on the carriage 14. A liquid tank 24 and a liquid supply means 19 adjoining to the tank 24 are installed on one end side of the rod 13. When liquid 17 is supplied to the part 18, the print head is moved to a liquid supply position, a plunger 20 above the part 18 is inserted into a plunger insertion hole 21, a liquid storage part 26 is moved to the print head side with the tank 24, and a liquid supply/discharge nozzle 22 is put into the part 26 from an opening 25. Moreover, the plunger 20 is pushed into the part 18, after a porous elastomer 23 being compressed, the plunger is pulled up, and liquid 17 is sucked from the nozzle 22 into the part 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can easily maintain a liquid supply system and can continuously perform a high-speed printing operation, and a print head used therefor.

[0002]

2. Description of the Related Art Generally, an image forming apparatus that prints image information on a print medium by ejecting liquid droplets from a print head intermittently scans the print medium in a first direction while moving the print head in the first direction. In many cases, scanning movement is performed along the print medium in a second direction orthogonal to the direction of.

In such an image forming apparatus,
In order to finish the printing operation in a short time, it is necessary to scan and move the print head as fast as possible. At the same time, it is also effective to increase the capacity of the liquid tank that stores liquid such as ink discharged from the print head. From this point of view, the thermal energy is applied to the liquid, the liquid is rapidly heated to generate air bubbles, and the volume expansion of the air bubbles causes the liquid in the liquid path to be ejected from the discharge port as droplets, thereby forming bubbles. An ink jet head in which liquid is introduced from the liquid chamber into the liquid path when it disappears has attracted attention as one of the most suitable ones for high-speed printing because of its good response to print signals.

Usually, a print head and a liquid tank in an ink jet printing apparatus are of a type in which these are integrated and mounted on a carriage, or a type in which the liquid tank and the print head are connected via a flexible liquid supply pipe. Are known, and are appropriately selected in accordance with the size of the apparatus itself, the time required for image formation, ease of use, and the like.

[0005]

In an ink jet printing apparatus in which a print head and a liquid tank are integrated and mounted on a carriage, a liquid supply system for supplying the liquid in the liquid tank to the print head is simplified. It is possible to

However, when a large-capacity liquid tank is used to perform a large amount of continuous printing processing, the inertial mass of a carriage that scans and moves together with the print head and the liquid tank increases, so that high-speed printing is performed. However, there is a disadvantage that a strong driving source is required and the whole apparatus becomes large.

On the other hand, in an ink jet printing apparatus in which the liquid tank is separated from the print head, it is not necessary to mount the liquid tank on the carriage, so that the inertial mass of the carriage is reduced, and even if the driving source has a small capacity, the carriage may be mounted on the carriage. Can be moved at high speed. Moreover, it is possible to use a large-capacity liquid tank, and it can be said that this is a type suitable for a large-scale continuous printing process.

However, the type in which the print head and the liquid tank are separated requires a liquid supply system having a liquid supply pipe for connecting the print head and the liquid tank, and has a disadvantage that the mechanism for this is complicated. In addition, the hardness of the liquid supply pipe changes depending on the temperature, and the tension of the liquid supply pipe changes depending on the position of the carriage and the liquid tank, which may adversely affect print quality.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of performing a large amount of print processing continuously and at a high speed, and a print head used for the image forming apparatus.

[0010]

According to a first aspect of the present invention, there is provided a carriage for scanning and moving along a print medium;
A liquid tank for storing liquid to be discharged from the print head, and a liquid replenishing means for replenishing the print head with the liquid in the liquid tank at a liquid replenishment position set at one end of the carriage in the scanning movement direction. An image forming apparatus is provided.

According to the present invention, when replenishing liquid to the print head mounted on the carriage, the print head is moved to the liquid replenishing position together with the carriage, and the liquid in the liquid tank is replenished to the print head by the liquid replenishing means. I do.

On the other hand, according to a second embodiment of the present invention, a carriage that scans and moves along a print medium, a liquid tank that stores liquid to be discharged from a print head, and scans the liquid in the liquid tank with the carriage A liquid supply unit configured to supply liquid to the print head at a liquid supply position set at one end in a movement direction, wherein the print head is detachable from the carriage. And a liquid holding unit attached to the print head and capable of holding a predetermined amount of liquid supplied by the liquid supply unit.

According to the present invention, when it becomes necessary to replenish the liquid holding portion of the print head, the print head is moved to the liquid replenishing position together with the carriage,
The liquid in the liquid tank is supplied into the liquid holding section of the print head using the liquid supply means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an image forming apparatus according to a first embodiment of the present invention, a liquid replenishing means may be arranged at one end of a carriage in a scanning movement direction. In this case, a liquid tank is provided adjacent to the liquid replenishing means. It is also possible to arrange them. Further, the liquid replenishing means may be disposed on the carriage side, and the liquid replenishing means may replenish the liquid to the print head after discharging the liquid held in the print head. Further, the apparatus further includes print event detection means for detecting an event related to a printing operation, and the liquid replenishment means may be one capable of replenishing liquid based on a detection result by the print event detection means. The event related to the printing operation may be a print medium transport operation. Further, the apparatus may further include a remaining amount detecting unit that detects a remaining amount of the liquid held in the print head, and the liquid replenishing unit may supply the liquid based on a detection result by the remaining amount detecting unit.

On the other hand, in the print head according to the second embodiment of the present invention, the liquid supply means may be provided in the print head. Further, the liquid holding section may have a porous elastic body, and in this case, the liquid replenishing means may include:
It may have a plunger capable of compressively deforming the porous elastic body. Further, the liquid may be a processing liquid for adjusting the characteristics of ink or ink ejected to a print medium.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to an ink jet printing apparatus will be described in detail with reference to FIGS.

FIG. 1 showing the schematic structure of the ink jet printing apparatus in this embodiment, FIG. 2 showing its plan shape, FIG. 3 showing its III-III cross-sectional structure, and FIG. 4 showing the control block of this embodiment are shown in FIG. As shown in FIG. 2, a carriage 14 is slidably provided on a guide rod 13 arranged in parallel with a print medium 12 such as paper conveyed in the vertical direction in FIG. The carriage 14 is reciprocally movable along the guide rod 13 by the carriage moving means 15. Carriage 1 by carriage moving means 15
A liquid replenishing position for replenishing the print head 16 with liquid 17 to be described later is set at one end in the scanning movement direction 4. The print head 16 mounted on the printer 14 is stopped at the liquid supply position in a positioned state.

A print head 16 having a liquid holding portion 18 for holding a liquid 17 such as ink is detachably mounted on the carriage 14. The print head 16 has a liquid 17 supplied from a liquid holding unit 18.
A number of discharge ports (not shown) for discharging the ink are arranged along the transport direction of the print medium 12, and the liquid 17 in each liquid path corresponds to a liquid path (not shown) communicating with each of these discharge ports. A discharge energy generating element (not shown) for discharging from the discharge port is incorporated. The liquid holding portion 18 has a plunger fitting hole 21 into which a plunger 20 of a liquid replenishing means 19 described later can be tightly inserted, and a liquid extending to the opposite side of the plunger fitting hole 21 across the liquid holding portion 18. A supply and discharge nozzle 22 is formed, and a predetermined amount of the liquid 17 is
Is accommodated therein.

At one end of the guide rod 13, a liquid tank 24 storing a liquid 17 and a liquid replenishing means 19 of the present invention provided adjacent to the liquid tank 24 are arranged. The liquid replenishing unit 19 includes a liquid storage unit 26 having an opening 25 into which the liquid supply / discharge nozzle 22 of the print head 16 is inserted, and the liquid storage unit 26 and the liquid tank 2.
4 and the liquid 17 in the liquid reservoir 26
For adjusting negative pressure to maintain the pressure at a predetermined liquid level
A plunger 20 located above the liquid holding portion 18 of the print head 16 at the liquid supply position and capable of reciprocating in a direction facing the plunger fitting hole 21, and not shown for reciprocating the plunger 20. Plunger moving means.

The liquid tank 24 and the negative pressure adjusting partition 2
The tank 7 and the liquid reservoir 26 are reciprocally movable in a direction opposite to the plunger 20 with respect to the print head 16 at the liquid supply position, and a tank moving means (not shown) for reciprocating these. Is provided.

The operations of the ejection energy generating section of the print head 16, the carriage moving means 15, the print medium moving means 11, the liquid replenishing means 19, the plunger moving means, the tank moving means, and the like are set in advance by the printer control unit 28. Is properly controlled in accordance with the procedures performed.

For example, when the liquid 17 is supplied to the liquid holding portion 18 of the print head 16, the carriage moving means 15 is operated as shown in FIG.
Is moved to the liquid supply position, the plunger 20 is inserted into the plunger fitting hole 21 from the standby position by operating the plunger moving means as shown in FIG. 6, and the liquid is further operated by operating the tank moving means as shown in FIG. The reservoir 26 is moved from the standby position to the print head 16 side together with the liquid tank 24 so that the liquid supply / discharge nozzle 22 is inserted into the opening 25 and enters the liquid reservoir 26.

Thereafter, as shown in FIG. 8, the plunger moving means is further actuated to push the plunger 20 into the liquid holding portion 18, compress the porous elastic body 23, and press the liquid together with the liquid 17 held therein. The air in the holding unit 18 is pushed out from the liquid supply / discharge nozzle 22 into the liquid 17 in the liquid storage unit 26 as bubbles 29. After the liquid 17 in the liquid holding unit 18 is discharged together with the air as shown in FIG.
The plunger moving means is actuated in the reverse direction to raise the plunger 20 upward in the drawing, thereby displacing the liquid 17 stored in the liquid storage section 26 with the liquid supply / discharge nozzle 22.
Is sucked into the liquid holding portion 18 from the inside.

Then, as shown in FIG. 11, the tank moving means is operated to pull out the liquid supply / discharge nozzle 22 from the opening 25, and the liquid storage section 26 is returned to the standby position together with the liquid tank 24, as shown in FIG. Then, the plunger moving means is operated to pull out the plunger 20 from the plunger fitting hole 21 and return to the original standby position.

As described above, when the liquid 17 is replenished, even if the liquid 17 remains in the liquid holding portion 18 of the print head 16, all the remaining liquid 17 is discharged, and the liquid 17 is emptied, and then the liquid 17 is emptied again. Since a certain amount of the liquid 17 is suctioned and supplied, complicated processing such as calculating the supply amount of the liquid 17 can be omitted, and a certain amount of the liquid 17 can be reliably supplied. It is.

In the above-described embodiment, the liquid tank 24, the negative pressure adjusting partition 27 and the liquid storage section 26 are moved by the tank moving means to the print head 16 at the liquid supply position.
Are reciprocated in the direction facing the liquid storage unit 26, while these are held in a fixed state in the housing of the printing apparatus, while the print head 16 is moved together with the liquid holding unit 18 in the direction facing the liquid storage unit 26 with respect to the carriage 14. You may make it reciprocate. In this case, it is preferable that a spring force is interposed between the carriage 14 and the print head 16, and the print head 16 is moved toward the liquid storage section 26 against the spring force. In the above-described embodiment, the liquid 17 is supplied from the liquid supply / discharge nozzle 22. However, such a liquid supply / discharge nozzle 22 is not formed, and the print head 1 is supplied.
The liquid 17 may be supplied from the discharge port 6.
Further, it is also effective to cover the opening 25 of the liquid storage section 26 with a thin film-shaped seal member cut radially from the center to prevent the liquid 17 from evaporating.

As described above, a small amount of the liquid 17 is stored in the liquid holding portion 18 of the print head 16 mounted on the carriage 14.
The liquid 17 is replenished every time a predetermined number of prints are performed. Since the replenishment of the liquid 17 requires a certain amount of time, the liquid retained in the liquid retaining portion 18 of the print head 16 is If the amount of 17 is too small, it will not be possible to improve the printing speed. Conversely, from the viewpoint of printing efficiency, it is desirable that more printing can be performed by one replenishment of the liquid 17. However, if an excessively large amount of liquid can be held by the liquid holding section 18 of the print head 16, the printing is performed. The weight of the head 16 is large, which does not fit the purpose of the present invention to realize high-speed scanning including the carriage 14.

In this embodiment, one replenishment of the liquid 17
The amount of the liquid 17 held in the liquid holding section 18 of the print head 16 was set so that printing could be sufficiently performed even if any image was printed for one page. Thus, if the replenishment of the liquid 17 is performed before the printing operation of one print medium 12 is started, a reliable printing operation on the one print medium 12 can be realized.

Before the ink held in the print head 16 runs out, the liquid 17 must be supplied to the liquid holding unit 1 without fail.
8 needs to be replenished. As a method of detecting the replenishment time of the liquid 17, the
Generally, a method is provided in which means for detecting the remaining amount of the liquid 17 is provided, or means for integrating the discharge amount of the liquid 17 is provided, and replenishment is performed based on these.

FIG. 13 shows an example of a work procedure when printing is performed on the print medium 12 covering a plurality of pages using the ink jet printing apparatus. That is, in step S1, the print medium moving means 11 is operated to feed the print medium 12, and in step S2, the liquid supply means 19 is operated to supply the liquid 17 to the print head 16. In step S3, the print medium moving means 11 and the carriage moving means 15 are driven to perform a printing operation on the print medium 12.

Then, it is determined in step S4 whether or not the printing operation for one page has been completed. If the printing operation for one page has not been completed, the process returns to step S3 to continue the printing operation. . If it is determined in step S4 that the printing operation for one page has been completed, the process proceeds to step S5, where the print medium moving means 11 is operated, and the print medium 12 having been printed is discharged. Then, in step S6, it is determined whether or not the printing operation on the print medium 12 corresponding to all pages to be printed has been completed.

If it is determined in step S6 that the printing operation on all the print media 12 has not been completed, the flow returns to step S1 to operate the print medium moving means 11 to supply a new print medium 12. A paper operation is performed, and a print operation corresponding to the next page is performed in the same manner as the previous case. If it is determined in step S6 that the printing operation for all the print media 12 has been completed, the printing operation is completed.

As described above, the amount of the liquid 17 supplied to the liquid holding portion 18 of the print head 16 is adjusted so that any image can be printed for one page in one liquid replenishing operation. By setting, there is no need to provide a means for detecting the remaining amount of the liquid 17 in the print head 16 and a means for detecting the discharge amount of the liquid 17 from the discharge port of the print head 16. The liquid 17 can be surely replenished before the liquid 17 held in the tank is exhausted. In addition, by simultaneously performing the operation of transporting the print medium 12 and the operation of replenishing the liquid 17, the time required for replenishing the liquid 17 can be saved.

The present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging a liquid, particularly in an ink jet system. The present invention brings about an excellent effect in an ink jet head of a type in which a state change of a liquid is caused by thermal energy or an ink jet printing apparatus. 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. Applying at least one drive signal to the electrothermal transducer that provides a rapid temperature rise exceeding nucleate boiling corresponding to the print information, thereby generating thermal energy in the electrothermal transducer and providing a thermal effect to the inkjet head. This is effective because film boiling occurs on the surface, and consequently, bubbles in the liquid corresponding to this drive signal can be formed one-to-one. By the growth and contraction of the bubble, the ink is ejected through the ejection 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. In addition,
US Patent No. 4 of the invention relating to the rate of temperature rise of the heat acting surface
By employing the conditions described in the specification of Japanese Patent No. 313124, more excellent printing can be performed.

The structure of the ink jet head is a combination of a discharge port, a flow path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications. In addition, the present invention includes 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 portion is arranged in a bent region. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. JP-A-59-138461 which discloses a configuration corresponding to a discharge section
The effects of the present invention are effective even if the configuration is based on the above publication. That is, according to the present invention, printing can be performed reliably and efficiently regardless of the form of the inkjet head.

Further, even in the case of the serial type as described above, an ink jet head fixed to the apparatus main body, or an electric connection with the apparatus main body or supply of liquid from the apparatus main body by being mounted on the apparatus main body. The present invention is also effective when a replaceable chip type ink jet head that enables the above is used.

It is preferable to add an ink jet head ejection recovery means, a preliminary auxiliary means, and the like as the structure of the ink jet printing apparatus of the present invention since the effects of the present invention can be further stabilized. Specific examples include capping means for the ink jet head, cleaning means, pressurizing or sucking means, an auxiliary heating element using an electrothermal transducer, another heating element, or a combination thereof. Heating means,
Preliminary ejection means for performing ejection other than printing can be used.

The type and number of ink jet heads to be mounted are, for example, not only one provided for a single color ink, but also a plurality of inks having different print colors and densities. A plurality may be provided. That is, for example, the print mode of the inkjet printing apparatus is not limited to the print mode of only the mainstream color such as black, but may be either an integrated inkjet head or a combination of a plurality of inkjet heads. The present invention is also very effective for an apparatus provided with at least one of the print modes of full-color printing or color mixing.

In addition, the form of the ink jet printing apparatus according to the present invention is not limited to the one used as an image output terminal of an information processing apparatus such as a computer.
A copying machine combined with a reader or the like, or a facsimile machine having a transmission / reception function may be used.

[0041]

According to the present invention, the print head and the liquid tank are separated from each other, and the liquid is supplied to the print head by the liquid supply means at the liquid supply position set at one end of the print head in the scanning movement direction. Therefore, a large-capacity liquid tank can be used, and high-speed scanning of the carriage can be performed, so that a large amount of printing operations can be continuously performed in a short time. Moreover, since the liquid tank is in a fixed state, the liquid tank can be easily replaced.

Further, since it is not necessary to connect the print head and the liquid tank via the liquid supply pipe, the print quality can be kept constant, and the whole image forming apparatus can be further downsized. is there.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a schematic structure of an embodiment in which an image forming apparatus according to the present invention is applied to an ink jet printing apparatus.

FIG. 2 is a plan view of the inkjet printing apparatus shown in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a control block diagram of the embodiment shown in FIG.

FIG. 5 is a work process chart showing a liquid supply procedure together with FIGS. 6 to 12.

FIG. 6 is a work process diagram showing a liquid replenishment procedure together with FIGS. 5, 7 to 12.

FIG. 7 is a work process diagram showing a liquid replenishment procedure together with FIGS. 5, 6, and 8 to 12.

FIG. 8 is an operation process diagram showing a liquid supply procedure together with FIGS. 5 to 7 and FIGS. 9 to 12.

9 is a work process diagram showing a liquid supply procedure together with FIGS. 5 to 8 and FIGS. 10 to 12. FIG.

FIG. 10 is a work process diagram showing a liquid replenishment procedure together with FIGS. 5 to 9, FIG. 11, and FIG.

FIG. 11 is a work process chart showing a liquid supply procedure together with FIGS. 5 to 10 and 12.

FIG. 12 is a work process chart showing a liquid supply procedure together with FIGS. 5 to 11;

FIG. 13 is a flowchart illustrating a print operation procedure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Print medium moving means 12 Print medium 13 Guide rod 14 Carriage 15 Carriage moving means 16 Print head 17 Liquid 18 Liquid holding part 19 Liquid replenishing means 20 Plunger 21 Plunger fitting hole 22 Liquid supply / discharge nozzle 23 Porous elastic body 24 Liquid tank 25 Opening 26 Liquid Storage 27 Negative Pressure Adjustment Partition 28 Printer Control Unit 29 Bubbles

Claims (13)

[Claims] A carriage that scans and moves along a print medium; a liquid tank that stores a liquid to be ejected from a print head; and a liquid that is set at one end of the carriage in the scanning movement direction of the carriage. An image forming apparatus comprising: a liquid supply unit that can supply the print head at a supply position. 2. The image forming apparatus according to claim 1, wherein the liquid supply unit is disposed at one end of the carriage in a scanning movement direction. 3. The image forming apparatus according to claim 2, wherein the liquid tank is disposed adjacent to the liquid supply unit. 4. The image forming apparatus according to claim 1, wherein the liquid replenishing unit is disposed on the carriage side. 5. The liquid supply device according to claim 1, wherein the liquid replenishing unit replenishes the liquid to the print head after discharging the liquid held in the print head. An image forming apparatus according to any one of the above. 6. A print event detecting means for detecting an event related to a printing operation, wherein said liquid replenishing means is capable of replenishing liquid based on a detection result by said print event detecting means. The image forming apparatus according to claim 1, wherein: 7. The image forming apparatus according to claim 6, wherein the event related to the print operation is a print medium transport operation. 8. A printer according to claim 1, further comprising: a remaining amount detecting unit for detecting a remaining amount of the liquid held by the print head, wherein the liquid replenishing unit is capable of replenishing the liquid based on a detection result by the remaining amount detecting unit. 2. The method according to claim 1, wherein
The image forming apparatus according to any one of claims 1 to 7. 9. A carriage that scans and moves along a print medium, a liquid tank that stores liquid to be ejected from a print head, and a liquid set in one end of the carriage in the scanning movement direction of the carriage. A print head used in an image forming apparatus having a liquid replenishing unit capable of replenishing the print head at a replenishing position, wherein the print head is detachably attached to the carriage and is provided by the liquid replenishing unit. A print head comprising a liquid holding portion capable of holding a predetermined amount of liquid to be replenished. 10. The print head according to claim 9, wherein said liquid supply means is provided in the print head. 11. The print head according to claim 9, wherein the liquid holding section has a porous elastic body. 12. The print head according to claim 11, wherein said liquid supply means has a plunger capable of compressively deforming said porous elastic body. 13. The printhead according to claim 9, wherein the liquid is a processing liquid for adjusting characteristics of ink and / or ink ejected to the print medium.