JPH10157154A - Ink supply device of ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To still more enhance the high quality printing and smooth production of an ink jet printer. SOLUTION: An ink tank 213 for each color is arranged at a position separated from a nozzle unit for each color and the ink buffer 206 in the nozzle unit 200 is connected to the ink tank 213 by an ink supply tube 215 and an ink replenishing tube 217 and an energizing means 216 is provided to the ink supply tube 215 while a tube opening and closing means 218 is provided to the ink replenishing tube 217 and, by starting and stopping the energizing means 216 and selecting the opening and closing operations of the tube opening and closing means 218, the initial supply of ink into the nozzle unit 200 (206), air venting and the changeover of ink supply during prime printing operation are enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a nozzle unit for each color which is held on the outer peripheral surface of a drum rotatable at a constant peripheral speed and is displaced in the rotation direction of a drum on a printing medium rotating with the drum. The present invention relates to an ink supply device of an ink jet printer formed so as to be capable of multicolor printing while spraying each color ink.

[0002]

2. Description of the Related Art A nozzle unit for each color is reciprocated over the entire length in a row direction, and printing is performed during each forward movement to print one line, and after one line printing, a printing medium (plain paper, OHP paper, etc.). Compared to a so-called serial type ink-jet printer which feeds M by one line in the column direction and repeats them, printing speed can be drastically increased and continuous printing operation can be performed over a large number of sheets. The present applicant has proposed an ink jet printer capable of achieving a large size reduction (for example, Japanese Patent Application No. 8-296957).

That is, in FIG. 7, a drum 10 is rotatable at a constant peripheral speed and can hold a print medium M on an outer peripheral surface 11 thereof. Rotation of this drum 10 (Y)
A nozzle unit 200 for each color is provided in the direction. Therefore, an integrated nozzle unit 200 for each color in the entire length in the row direction (perpendicular to the paper surface) or an integrated nozzle unit 200 for each color in which a plurality of nozzle unit elements are arranged in the row direction is provided, for example, by the pitch between inkjet nozzles. The printing can be performed in the row direction on the rotating print medium M while reciprocating, and can be performed in the column direction using the rotation of the drum 10 during the forward movement within the pitch between the inkjet nozzles. That is, since the line-direction printing and the column-direction printing can proceed simultaneously, the printing speed can be greatly increased.

[0004] Since the nozzle unit 200 for each color and the ink tank (ink cassette) 213 for each color are arranged at a distance from each other, the nozzle unit 200 for each color can be lightened, and the reciprocating speed in the row direction can be greatly increased. In addition, the printing speed can be further increased, and the capacity of the ink tank (ink cassette) 213 for each color can be greatly increased, so that a continuous printing operation of, for example, 500 or more sheets can be performed.

In order to realize these, one side (right side in the figure) of the drum 10 is provided with a feeding means 60 and a medium feeding means 90.
The other (left) side is provided with a medium peeling unit 140, a medium discharging / conveying unit 160, and a direction switching unit 190.

The feeding means 60 can selectively feed the printing medium M one by one from one of the cassette feeding means 71 and the manual feeding means 61. The medium supply means 90 feeds the fed print medium M to the drum 1 at a predetermined timing.
Feed to the 0 side. The medium peeling means 140 peels the print medium M from the drum 10 after printing, and outputs the medium discharge and transport means 1
Reference numeral 60 discharges and transports the separated print medium M to the left in the figure. The direction switching means 190 selectively switches between the discharge tray 92 and the upper discharge tray 193.

In this way, since the feeding, supply, holding, printing, peeling, and discharging and conveying of the printing medium M can be continuously performed, multicolor printing of, for example, 20 sheets or more of A4 size can be performed in one minute.

[0008]

By the way, in order for the proposed printer to smoothly perform printing operation with higher quality, the structure and performance of an ink supply device including an ink tank 213 spaced apart from the nozzle unit 200 for each color. Needs to be further improved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink supply apparatus for an ink jet printer which can further improve high quality printing and smooth printing.

[0010]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a plurality of colors which are held on an outer peripheral surface of a drum rotatable at a constant peripheral speed and are displaced in a rotation direction of a drum on a printing medium rotating with the drum. An ink supply device of an ink jet printer formed to be capable of multicolor printing while spraying each color ink using a nozzle unit for each color, wherein an ink tank for each color is arranged at a position away from the nozzle unit for each color and The ink buffer in the nozzle unit for each color and the ink tank for each color are connected by an ink supply tube and an ink supply tube, and a biasing unit is provided for each ink supply tube, and a tube opening / closing unit is provided for each ink supply tube. Start / stop of each biasing means and open / close operation of each tube opening / closing means for each color Initial ink supply to the nozzle unit, an air vent, an ink supply device for an inkjet printer that the ink supply is switchable formed in prime and printing operation.

In this invention, each of the urging means is activated,
The ink in each ink tank is initially supplied into the ink buffer of the nozzle unit for each color through the ink supply tube. Thereafter, if the ink supply tubes are closed by closing the respective tube opening / closing means, air bleeding and clogging of the ink buffer and the ink jet nozzles can be eliminated. After printing, each ink jet nozzle can be cleaned to prevent clogging. During printing operation,
Each urging means is stopped, and each tube opening / closing means is opened. Therefore, the ink in each ink tank is replenished into each ink buffer by the amount of printing consumption through the ink replenishment tube by capillary action. Therefore, even if each nozzle unit is separated from each ink tank, a high quality and smooth printing operation can be performed.

Further, according to a second aspect of the present invention, the ink tank for each color is disposed at a position lower than the nozzle unit for each color, and the height difference between the ink tank for each color and the nozzle unit for each color is the same. It is an ink supply device for an ink jet printer.

According to this invention, the ink tank for each color (specifically, the liquid level of the ink in the ink tank) is located at a position lower than the nozzle unit for each color (specifically, the ink surface at the tip of the nozzle), and the height difference is set. Are the same, the same operation and effect as those of the first aspect of the invention can be obtained. In addition, since the ink spray conditions (meniscus) from the nozzle units for each color are made uniform, high quality printing can be further achieved. Can be performed stably.

According to a third aspect of the present invention, the ink cassette is detachable from the ink tank for each color via a liquid level fixing means capable of holding the ink level in the ink tank for each color constant. Ink supply device for an ink jet printer.

In this invention, ink is supplied from the ink cassette through the liquid level fixing means, and the ink liquid level in each color ink tank is kept constant. Therefore, in addition to providing the same operational effects as those of the first and second aspects of the invention, the ink spray condition from the nozzle unit for each color can be kept constant, so that the printing quality can be further improved and the printing quality can be improved. The ink cassette can be exchanged during the operation, and a continuous printing operation of a larger number of sheets can be performed.

Further, the invention of claim 4 is an ink supply apparatus for a rotary type ink jet printer, wherein each of said urging means has a plurality of pressing rollers arranged at equal intervals.

In this invention, since each of the urging means is a rotary type including a plurality of pressing rollers, the same operation and effect as those of the first to third aspects can be obtained. Further, the ink supply can be further stabilized through the ink supply tube, and the oversupply to the ink buffer and the phenomenon of ink return to the ink tank side can be eliminated, so that a more stable printing operation can be performed.

The invention according to claim 5 is an ink supply device for an ink jet printer, wherein each of the urging means is rotatable by the same motor.

In this invention, each of the urging means is rotated by the same motor, that is, started and stopped.
In addition to the same effects as those of the invention, the ink can be simultaneously supplied to the nozzle units for each color, so that the start-up time can be minimized and the control can be facilitated.

Further, according to the present invention, there is provided an ink supply apparatus for an ink jet printer, wherein said ink tank for each color is provided with a static pressure constant means for communicating the inside of said ink tank for each color with the atmosphere during a printing operation. It is.

In this invention, during the printing operation, the inside of each color ink tank is communicated with the atmosphere by the static pressure stabilizing means, and the static pressure of each color ink is stabilized. Therefore, the same effects as those of the first to fifth aspects of the invention can be obtained, and the replenishment and spraying characteristics of each color ink can be further uniformed.

Further, the invention according to claim 7 is characterized in that each of the tube opening / closing means is a rotary type having one pressing roller, and one open-to-atmosphere tube common to each static pressure stabilizing means is provided.
An ink supply device of an ink jet printer in which each of the tube opening and closing means and the atmosphere opening tube opening and closing means can be opened and closed by the same motor and can be opened and closed by a rotary type atmosphere opening tube opening and closing means having two pressing rollers. is there.

In this invention, for example, when the motor is rotated to perform the opening operation during the printing operation, the pressing roller of each tube opening / closing means simultaneously opens each ink supply tube, and the pressing roller of the atmosphere opening tube opening / closing means presses the atmosphere. Open the release tube. Therefore, ink can be supplied uniformly and stably through each ink supply tube under a constant static pressure. If the motor is rotated and closed during a period other than during the printing operation, the atmosphere opening tube can be closed, so that the ink in the ink tank for each color can be prevented from drying. Therefore, the same operation and effect as the case of the invention described in claim 6 can be obtained, and further, each of the tube opening and closing means and the atmosphere opening tube opening and closing means can be simplified and the operation can be facilitated.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the ink supply device 210 of the present inkjet printer arranges the ink tanks 213 for each color at a position separated from the nozzle units 200 for each color, and
Ink buffer 206 and ink tank 2 for each color
13 is connected by an ink supply tube 215 and an ink supply tube 217, a biasing means 216 is provided in each ink supply tube 215, and a tube opening / closing means 218 is provided in each ink supply tube 217.
16 start / stop and respective tube opening / closing means 218
By selecting the opening operation / closing operation, the initial supply of ink into the nozzle unit 200 (206) for each color, air bleeding, priming, and ink supply during printing operation can be switched.

The ink jet printer of this embodiment has the same structure as that of the proposed ink jet printer shown in FIG.

In FIG. 1, the nozzle units 200 for each color (C, M, Y, B) are a plurality (for example, four) of nozzle units arranged in a direction perpendicular to the plane of FIG. Each nozzle unit element 20
5 is provided with a large number (for example, 159) of inkjet nozzles 207.

The ink jet system is not limited, but
In this embodiment, ink is jetted by the spray control element 208 using the shear deformation of the piezoelectric actuator.

Each ink jet nozzle 207 of each nozzle unit element 205 is connected to a common ink buffer (pressure chamber) 206. Except during the printing operation, the ink is covered with the cap 231 to prevent the ink from drying. A waste ink collecting means is formed from the waste ink tube 232, the waste ink tank 234 having the waste ink pump 233, and the sponge 235.

Here, the nozzle units 200 (ink buffer 206) for each color and the ink tank 213 which are separately provided are connected (communicated) with an ink supply tube 215 and an ink supply tube 217.

When the urging means 216 is activated, the ink supply tube 215 causes the ink tank 213 to operate.
Can be supplied into the ink buffer 206. The ink supply tube 215 is opened by the tube opening / closing means 218 so that the ink buffer 2 is opened.
06 can be supplied with ink from the ink tank 213.

The urging means 216 is of a rotary type having a plurality (four) of pressing rollers 216R arranged at equal intervals on a circular locus, and each pressing roller 216R rotates and moves along a guide 216G. Sometimes, the ink supply tube 215
The ink inside can be supplied by extruding the ink inside to the ink buffer 206 side. Therefore, the phenomenon of oversupply and the return of ink to the ink tank 213 can be eliminated.

Each of the urging means 216 for each color is shown in FIG.
As shown in the figure, the motor 216M can be driven (rotated) and stopped synchronously by one motor 216M. This is for simplifying the structure and facilitating the control. Further, the start-up time of the ink supply can be minimized.

Each tube opening / closing means 218 is of a rotary type having one pressing roller 218. In FIG. 1, the ink supply tube 217 is pressed against a guide 218G, which is simply shown in FIG. Become. Each tube opening / closing means 218 is rotated and stopped by one motor 218M as shown in FIG. Control simplification similar to the case of each urging means 216 can be achieved.

Further, in this embodiment, the open / close tube opening means 219 described later in detail also uses the same motor 218.
It is formed to rotate at M. Therefore, simplification and simplification of operation of both means 218 and 219 can be further promoted.

However, as shown in ST12 and ST18 of FIG. 5, the opening (closing) operation of each tube opening / closing means 218 and the closing (opening) operation of the atmosphere opening tube opening / closing means 219 are made possible, that is, the operation can be reversed. , Pressing roller 218
R and 219R are mounted so as to be displaced by 180 degrees. In the case of the opening operation shown in ST15 of FIG. 5, it is only necessary to make a quarter turn from the state shown in FIG.

The ink tank 213 for each color has an upper portion formed so that an ink cassette 211 can be attached and detached via a liquid level fixing means 212, and a filter 214 provided at a lower portion. The ink liquid level is kept constant by the liquid level stabilizing means 212.

As shown in FIG. 4, the liquid level stabilizing means 212 is formed so as to be able to perform a leveling operation by detecting a change in the level of the ink liquid in the ink tank 213. That is, when the ink cassette 211 is inserted downward in the figure, the protrusion 213A provided in the ink tank 213 is
The cap 212C is pushed up within the cap guide 212G against the downward urging force of the cap 212C. Then, 2 in the lower part of the cassette
The ink in 11D flows into the ink tank 213 through the inlet 212H of the cap guide 212G and the supply port 211H at the bottom of the cassette.

When the ink level in the ink tank 213 rises and reaches the supply port 211H, the ink flow stops. When the ink level in the ink tank 213 drops below the supply port 211H due to a printing operation or the like, ink flows again. Therefore, the ink liquid level in the ink tank 213 can always be kept constant.

The ink level in each ink tank 213 is arranged at a position lower than the ink level at the nozzle outlet (tip) of each color nozzle unit 200 (nozzle unit element 205). By applying a suction negative pressure to each nozzle 207, it is possible to prevent ink leakage (outflow) from each inkjet nozzle 207. Further, the height difference h between the two 213 and 200 (205) is the same. However, the same includes a slight difference finely adjusted according to the ink characteristics.

Therefore, each color nozzle unit 200
Since the ink spray condition (meniscus) from (205) can be made more uniform, more stable high-quality printing can be performed, and the ink cassette 211 can be replaced during the printing operation. Can be performed.

Next, the static pressure stabilizing means for communicating the inside of each ink tank 213 with the atmosphere during the printing operation to stabilize the static pressure applied to the ink in each ink tank 213 is provided. Are connected to the respective ink tanks 213 and the other end is connected to the manifold 219H, and an individual air release tube 219Lb is connected to the manifold 219H.
And an atmosphere opening tube opening / closing means 219 for opening and closing the atmosphere opening / closing tube. This means 219 is also a rotary type having one pressing roller 219R, and is rotationally driven by the motor 218M as described above. Therefore, the replenishment and spraying characteristics of each color ink can be made more uniform.

The control unit 250 shown in FIG.
Although the entire ink jet printer can be drive-controlled including U, ROM, RAM and the like, the motors 216M and 218M are driven and controlled for the ink supply device 210 in the procedure shown in FIG. This procedure will be described with the following operation and operation.

Next, the operation and operation of this embodiment will be described. Prime request occurs (YE in ST10 of FIG. 6)
When S) is performed, the control unit 250 starts (rotates) each urging means (motor 216M) 216 (ST1).
1). By switching the urging means 216, ink is supplied from the ink tank 213 into the ink buffer 206 through the ink supply tube 215.

At this time, most of the air in the ink buffer 206 escapes at the same time as the supply or
After the ink is ejected from the nozzle and clogging is prevented, the control unit 250 operates the tube opening / closing means 218 and the atmosphere opening tube opening / closing means 219. That is, the motor 21
8M is rotated to switch to the state shown in FIG.

Therefore, each ink supply tube 217
Are closed and open to the atmosphere 219 L (219 L each)
b) is released. When each ink supply tube 217 is closed, the pressure in each ink buffer 216 increases, so that the air remaining in the ink buffer 216 as well as in the ink jet nozzle 217 can be completely rejected (vented) through the ink jet nozzle 217. it can. Note that the initial supply of ink is executed in a similar procedure.

Next, when the printing operation (request) starts, the control unit 250 stops the urging means 216 (ST1 in FIG. 6).
3 YES, ST14) and each tube opening / closing means 21
8 and the open-to-atmosphere tube opening / closing means 219 are switched to the opening operation. Therefore, each ink supply tube 217 and the atmosphere opening tube 219L are opened (ST15).

Thus, in each ink buffer 206,
The ink corresponding to the printing consumption is supplied from each ink tank 213 through each ink supply tube 217 by a capillary phenomenon as shown by a solid line arrow in FIG. The ink level in each ink tank 213 is kept constant by the liquid level stabilizing means 212 shown in FIG.

The static pressure stabilizing means (219, 219L)
b, 219L), the static pressure in each of the ink tanks 213 is constant, so that uniform and stable ink replenishment is performed. When printing is stopped (YES in ST16), the urging means 218 is stopped (ST17), and the ink supply tube 2 is stopped.
17 is opened and the open-to-atmosphere tube 219L is closed. Therefore, the ink can be prevented from drying in each ink tank 213 by these switching.

Before stopping printing, ST10 to ST
In the same procedure as in 12, cleaning of each ink jet nozzle 207 is performed, and after cleaning, the cap 231 covers each ink jet nozzle 207 to prevent ink drying and clogging.

[0050]

According to the first aspect of the present invention, the ink tank for each color is disposed at a position distant from the nozzle unit for each color, and the ink buffer in the nozzle unit for each color and the ink tank for each color are connected. Connected by an ink supply tube and an ink supply tube, each ink supply tube is provided with a biasing means, and each ink supply tube is provided with a tube opening / closing means, to start / stop each biasing means and open the respective tube opening / closing means.・ Initial supply of ink into the nozzle unit for each color by selecting the closing operation,
Since the air bleeding, the priming, and the ink supply during the printing operation can be switched, high quality and smooth printing operation can be performed even if each nozzle unit is separated from each ink tank.

According to the second aspect of the present invention, the ink tank for each color is disposed at a position lower than the nozzle unit for each color, and the height difference between the ink tank for each color and the nozzle unit for each color is the same. Therefore, the same effects as those of the first aspect of the invention can be obtained. In addition, since the conditions for spraying ink from the nozzle units for each color are made uniform, high-quality printing can be performed more stably.

According to the third aspect of the present invention, the ink cassette can be attached to and detached from each color ink tank via each liquid level fixing means capable of holding the ink liquid level in each color ink tank constant. Therefore, the same effects as those of the first and second aspects of the present invention can be obtained, and the ink spray condition from the nozzle unit for each color can be kept constant, so that the printing quality can be further improved. In addition, the ink cassette can be replaced during the printing operation, and a continuous printing operation for a larger number of sheets can be performed.

According to the fourth aspect of the present invention, since each of the urging means is a rotary type having a plurality of pressing rollers arranged at equal intervals, the inventions of the first to third aspects are provided. In addition to the same effects as in the above case, the ink supply can be further stabilized through the ink supply tube, and over-supply to the ink buffer and ink return to the ink tank can be eliminated. Can be.

According to the fifth aspect of the present invention, since each of the urging means is rotatable by the same motor, the same effect as that of the fourth aspect of the present invention can be obtained. Since the ink can be supplied to the nozzle unit at the same time, the start-up time can be minimized and the control can be facilitated.

Further, according to the invention of claim 6, since the ink tank for each color is provided with a static pressure stabilizing means for communicating the inside of the ink tank for each color and the atmosphere during the printing operation, In addition to the effects similar to those of the inventions according to the first to fifth aspects, the replenishment and spraying characteristics of each color ink can be further stabilized.

Further, according to the invention of claim 7, each tube opening / closing means is a rotary type having one pressing roller, and the open-to-atmosphere tube common to each static pressure stabilizing means has one pressing roller. Since the rotation type open / close tube opening / closing means can be opened and closed and each tube opening / closing means and the open air tube opening / closing means are formed so as to be openable / closable by the same motor, the same as in the case of the invention according to claim 6 In addition to the above advantages, the tube opening / closing means and the atmosphere opening tube opening / closing means can be simplified and easily operated.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a plan view for explaining an urging means.

FIG. 3 is a plan view for explaining a tube opening / closing means and an atmosphere opening tube opening / closing means.

FIG. 4 is also a view for explaining a liquid level stabilizing means.

FIG. 5 is also a diagram for explaining a control unit.

FIG. 6 is a flowchart for explaining the operation.

FIG. 7 is a diagram illustrating an ink jet printer.

[Explanation of symbols]

 Reference Signs List 10 drum 11 outer peripheral surface 200 nozzle unit for each color 205 nozzle unit element 206 ink buffer 207 inkjet nozzle 208 spraying control element 210 ink supply device 211 ink cassette 212 liquid level stabilizing means 212C cap 213 ink tank 214 filter 215 with ink supply tube 216 Urging means 216R pressing roller 216G guide 216M motor 217 ink supply tube 218 tube opening / closing means 218R pressing roller 218G guide 218M motor 219 open air opening / closing means (static pressure stabilizing means) 219R pressing roller 219Lb individual air opening tube (static pressure constant) Means) 219H Manifold 219L Atmospheric release tube (Static pressure stabilizing means) M Printing medium

Claims (7)

[Claims] 1. A method of spraying each color ink onto a print medium held on the outer peripheral surface of a drum rotatable at a constant peripheral speed and using a nozzle unit for each color that is displaced in the direction of rotation of the drum on a print medium rotating with the drum. An ink supply device for an ink jet printer formed so as to be capable of multicolor printing while disposing an ink tank for each color at a position separated from the nozzle unit for each color, and an ink buffer in the nozzle unit for each color, and The ink tanks for each color are connected to each other by ink supply tubes and ink supply tubes. Each ink supply tube is provided with a biasing means, and each ink supply tube is provided with a tube opening / closing means. Opening operation of tube opening / closing means
An ink supply device for an ink jet printer which is configured to be capable of switching between initial supply of ink into each color nozzle unit, air bleeding, priming, and ink supply during printing operation by selecting a closing operation. 2. The ink tank for each color is disposed at a lower position than the nozzle unit for each color, and the height difference between the ink tank for each color and the nozzle unit for each color is the same. An ink supply device for an ink jet printer as described in the above. 3. An ink cassette is detachably attached to each color ink tank via each liquid level fixing means capable of holding the ink liquid level in each color ink tank constant. Item 3. An ink supply device for an ink jet printer according to Item 2. 4. An ink jet printer according to claim 1, wherein each of said urging means is a rotary type having a plurality of pressing rollers arranged at equal intervals. Ink supply device. 5. The ink supply device for an ink jet printer according to claim 4, wherein each of said urging means is rotatable by a same motor. 6. The ink tank for each color according to claim 1, further comprising a static pressure stabilizing means for communicating the inside of the ink tank for each color with the atmosphere during a printing operation. An ink supply device for an ink-jet printer described in (1). 7. Each of the tube opening and closing means is a rotary type having one pressing roller, and a common air opening tube common to each static pressure stabilizing means is a rotary type air opening and closing means having one pressing roller. 7. The ink supply device of an ink jet printer according to claim 6, wherein each of said tube opening and closing means and said open-to-atmosphere tube opening and closing means are openable and closable by the same motor.