JPH10235907A - Color ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the overall structure of a head while eliminating or simplifying adjustment of positional shift between heads by employing a share mode type color ink jet head. SOLUTION: A large number of grooves are made in a board obtained by pasting piezoelectric members 31, 32 with the length of the groove being differentiated for yellow, magenta, cyan and black inks and a top plate 38 is fixed onto each groove through a spacer 36. The spacer is provided with ink supply holes for respective colors at the positions corresponding to the rear end of respective grooves and the top plate is provided with yellow, magenta, cyan and black ink supply paths 37Y, 37M, 37C and 37K for supplying ink of respective colors to the top plate. Since the position of ink supply hole for each color depends on the length of the groove, the ink supply paths 37Y, 37M, 37C and 37K can be formed in parallel in the top plate 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color ink jet printer in which inks of a plurality of colors are alternately and repeatedly arranged on an ink jet head, and color printing is performed by superposing ink tots of each color while controlling the movement of the head.

[0002]

2. Description of the Related Art Conventionally, as this type of color ink jet printer, one described in Japanese Patent Application Laid-Open No. H10-10948 is known. This is an on-demand type color ink-jet printer equipped with a plurality of piezoelectric elements corresponding to a plurality of nozzles. The nozzles are arranged in four color nozzles of a yellow ink nozzle, a magenta ink nozzle, a cyan ink nozzle, and a black ink nozzle. A color ink jet head is used in which one unit is one unit and a plurality of nozzle units are arranged in a line in parallel. More specifically, each ink chamber of the head is formed by laminating a plurality of laminated thin plates, and an ink supply path for each color is formed in a laminated portion of the laminated thin plates.

However, in the ink supply system described in this publication, a plurality of long U-shaped grooves having a front end opened and a rear end closed in a piezoelectric member are formed in parallel, and these grooves are used as ink chambers. There is a problem that cannot be applied to the so-called share mode type color inkjet head that is configured. That is, in the share mode type color inkjet head, two polarized piezoelectric members are bonded to each other with their polarization directions facing each other, and a predetermined pitch, depth,
A plurality of length grooves are formed in parallel to form an ink chamber.
The configuration is completely different from that of the publication in which an ink chamber is formed by laminating a plurality of laminated thin plates. For this reason, a method of forming an ink supply path for each color in a laminated portion of the laminated thin plate described in the publication is applied. It is not possible.

On the other hand, in a conventional printer for performing color printing using a share mode type ink jet head, ink jet heads are prepared for each of the four colors, arranged in parallel, and each ink jet head is individually driven. It is a method of overlapping the ink dots of each color
There has been a problem that the configuration of the entire head becomes large, and adjustment of the positional deviation between the four heads becomes troublesome.

[0005]

As described above, conventionally, in a printer which performs color printing using a share mode type ink jet head, the configuration of the entire head becomes large and adjustment of the position between the heads is troublesome. There was a problem.

Therefore, according to the first to fourth aspects of the present invention, in the case of performing color printing using an ink jet head of a share mode type, it is possible to reduce the overall configuration of the head, and it is unnecessary or simple to adjust the positional deviation between the heads. Provide a color ink-jet printer that can be used.

Further, the inventions according to the second and third aspects provide a color ink jet printer capable of equalizing the amount of ink of each color to be discharged and improving the printing quality.

Further, the invention according to claim 4 provides a color ink jet printer capable of further uniforming the ink amount of each color to be ejected and further improving the printing quality.

[0009]

According to the first aspect of the present invention,
A plurality of long U-shaped grooves are formed in parallel at the front end of the piezoelectric member and the rear end is closed, and a top plate is provided above each of the grooves via a spacer, and an ink discharge port is provided at the front end. In addition, a plurality of rectangular ink chambers are formed by providing ink supply holes in the spacer at the upper end of the rear end, and the plurality of inks used in each of the ink chambers are stored so as to be periodically arranged in a predetermined order. Then, the piezoelectric member forming the side wall is displaced by the application of the driving voltage, thereby deforming the ink chamber to discharge the ink from the ink discharge port, and moving the ink jet head in the direction in which the ink chambers are arranged. Movement control means for controlling the printing medium; printing medium transport means for transporting the printing medium in a direction orthogonal to the direction in which the ink chambers of the ink jet heads are arranged; And a ink chamber drive control means for deforming and driving controls each ink chamber of the inkjet head together with the conveying of the recording medium due to the movement control and the recording medium conveying means click jet head, ink jet head,
Moving control means for changing the length of the groove in accordance with the color of the ink to be stored and forming ink supply paths for the number of ink colors to be used for supplying ink commonly to ink supply holes of the same ink color on the top plate; The recording medium transport means and the ink chamber drive control means print a dot row in the transport direction on the recording medium and control the movement of the inkjet head so that the ink dots of each color overlap the same position, transport the recording medium, An object of the present invention is to control deformation driving of each ink chamber of the ink jet head.

According to a second aspect of the present invention, a plurality of long U-shaped grooves having a front end opened and a rear end closed on the piezoelectric member are formed in parallel, and a spacer is provided above each of the grooves by a spacer. A top plate is provided, an ink ejection port is provided at a front end, and an ink supply hole is provided in a spacer at an upper end of a rear end to form a plurality of rectangular ink chambers. An ink-jet head which is housed so as to be periodically arranged in order, and displaces a piezoelectric member constituting a side wall by application of a driving voltage, thereby deforming an ink chamber and discharging ink from an ink discharge port; Movement control means for controlling the movement of the head in the direction in which the ink chambers are arranged, and a recording medium transporter for transporting the recording medium in a direction orthogonal to the direction in which the ink chambers of the inkjet head are arranged. And, during printing, an ink chamber drive control unit that controls the movement of the inkjet head by the movement control unit and the deformation and control of each ink chamber of the inkjet head together with the conveyance of the recording medium by the recording medium conveyance unit. The length of the groove is varied according to the color of the ink to be stored, and the ink supply paths for the number of ink colors to be used for supplying the ink to the ink supply holes of the same ink color are formed on the top plate. The depth of the groove is adjusted according to the length of the groove so that the amount of ink discharged from the chamber is substantially the same, and the movement control means, the recording medium transport means, and the ink chamber drive control means transport the ink to the recording medium. Control the movement of the inkjet head so that the ink dots of each color overlap the same position, Lies in performing each deformation drive control of the respective ink chambers Ettoheddo.

According to a third aspect of the present invention, a plurality of long U-shaped grooves having a front end opened and a rear end closed on the piezoelectric member are formed in parallel, and a spacer is provided above each of the grooves by a spacer. A top plate is provided, an ink ejection port is provided at a front end, and an ink supply hole is provided in a spacer at an upper end of a rear end to form a plurality of rectangular ink chambers. An ink-jet head which is housed so as to be periodically arranged in order, and displaces a piezoelectric member constituting a side wall by application of a driving voltage, thereby deforming an ink chamber and discharging ink from an ink discharge port; Movement control means for controlling the movement of the head in the direction in which the ink chambers are arranged, and a recording medium transporter for transporting the recording medium in a direction orthogonal to the direction in which the ink chambers of the inkjet head are arranged. And an ink chamber drive control means for controlling the movement of the ink jet head by the movement control means during printing and the conveyance of the recording medium by the recording medium conveying means and the deformation and control of each ink chamber of the ink jet head. The length of the groove is varied according to the color of the ink to be used, and the ink supply paths for the number of ink colors to be used to supply ink to the ink supply holes of the same ink color are formed on the top plate, and each ink chamber is formed. The drive voltage value applied to the piezoelectric member is adjusted according to the length of the groove so that the amount of ink ejected from the recording medium is substantially the same, and the movement control means, the recording medium transport means, and the ink chamber drive control means On the other hand, print the dot rows in the transport direction and control the movement of the inkjet head so that the ink dots of each color overlap the same position. There conveyance of the respective ink chambers of the ink jet head modified drive control to be performed, respectively.

According to a fourth aspect of the present invention, in the color ink jet printer according to the second or third aspect, fine adjustment of the amount of ink discharged from each ink chamber is achieved by adjusting the pulse width of the drive voltage applied to the piezoelectric member. Is to do.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main part configuration of the entire printer. A rotating drum 2 which rotates at a constant peripheral speed in a direction indicated by an arrow in the drawing is provided as a recording medium conveying means in a main body case 1. A recording paper 5 which is a recording medium fed through paper feed rollers 3 and 4 is wound around the paper.

That is, a paper feed cassette 6 is provided at the bottom of the main body case 1, and the recording papers 5 placed on a mounting plate 7 of the paper feed cassette 6 are taken out one by one by a feed roller 8 and The recording paper 5 fed from the manual feed tray 9 which is openably and closably mounted on the side of the main body case 1 is fed to the paper feed rollers 3 and 4 by the feed roller 10. It is designed to be fed. The feed roller 8
The switching between the feeding by the feeding roller 10 and the feeding by the feeding roller 10 is performed by the feeding switching means 11.

On the rotating drum 2, the paper feed rollers 3,
A charging roller 12 for adsorbing the recording paper 5 fed from the drum 4 onto the drum surface is disposed opposite to the charging roller 12. A color ink jet head 13 of a share mode type in which a large number of ink chambers are arranged in a line is provided on the rotary drum 2 so as to be movable in the rotation axis direction of the rotary drum 2, that is, in the direction in which the ink chambers are arranged. The printing mechanism 14 is disposed opposite to the printing mechanism.

The printing mechanism 14 includes a reciprocating mechanism 15 on which the inkjet head 13 is mounted, a motor unit 16 having a reciprocating rod and a linear motor,
The inkjet head 13 is moved forward and backward with respect to the rotary drum 2 by the forward and backward moving means 17.
The reciprocating mechanism 15 is controlled to move in the direction of the rotation axis of the rotary drum 2 so that the inkjet head 13 is reciprocated in the direction of the rotation axis of the rotary drum 2.

A separating claw 18 that can be inserted between the drum surface and the recording paper 5 is disposed on the rotary drum 2, and the recording paper 5 separated by the separating claw 18 is transferred to a recording paper discharging and conveying means 19. It is designed to discharge. The recording paper discharging / conveying means 19 is composed of a belt conveyor 20 in contact with the non-recording surface of the recording paper 5 and a pressing means 21 for pressing the recording paper 5 against the surface of the belt conveyor 20.

At the end of the belt conveyor 20, the recording paper 5 conveyed by the belt conveyor 20 is discharged to an upper discharge tray 22 formed on the upper part of the main body case 1 or provided on a side surface of the main body case 1. Direction switching means 24 for switching the discharge to the detachable discharge tray 23. Reference numeral 25 denotes an ink drying unit, 26 denotes a main motor, 27 denotes an ink cassette, 28 denotes an ink buffer, and 29 denotes an ink supply tube.

Next, the manufacturing process of the ink jet head 13 will be described. First, as shown in FIG.
As shown by arrows in the figure, two piezoelectric members 31 and 32 polarized in directions opposite to each other in the plate thickness direction are bonded by bonding with the piezoelectric member 31 up and the piezoelectric member 32 down.
The bonded piezoelectric members 31 and 32 are polished to a predetermined thickness. For example, the piezoelectric member 31 is polished to a thickness of 0.2 mm and the piezoelectric member 32 is polished to a thickness of 1.1 mm.

As shown in FIG. 2B, a predetermined pitch is first applied to a substrate formed by bonding and polishing the two piezoelectric members 31 and 32 by a multi-cutter made of a diamond wheel or the like. A plurality of dummy grooves 33D having a predetermined depth and a predetermined length are formed in parallel. Next, FIG.
As shown in (c), a plurality of yellow ink grooves 33Y having a predetermined pitch, a predetermined depth, and a predetermined length are formed in parallel between the predetermined dummy grooves 33D by the same multi-cutter.

Next, as shown in FIG. 2D, a plurality of magenta ink grooves 33M having a predetermined pitch, a predetermined depth, and a predetermined length are similarly formed between the predetermined dummy grooves 33D by the multi-cutter. Are formed in parallel with each other. Next, as shown in FIG. 2 (e), a plurality of grooves 33C for cyan ink having a predetermined pitch, a predetermined depth and a predetermined length are similarly formed by the multi-cutter.
Are formed in parallel between predetermined dummy grooves 33D. Finally, as shown in FIG. 2 (f), a plurality of black ink grooves 33K having a predetermined pitch, a predetermined depth and a predetermined length are formed in parallel between the predetermined dummy grooves 33D by the same multi-cutter. I do.

As shown in FIG. 3, the grooves 33Y and 33 corresponding to the inks of yellow, magenta, cyan and black are formed on the substrate composed of the piezoelectric members 31 and 32.
M, 33C and 33K are periodically formed in a predetermined order via a dummy groove 33D.

These grooves 33Y, 33M, 33C, 33
K is a long U-shaped groove having an open front end and a closed rear end, and the dummy groove 33D has the longest groove length and the deepest groove depth. The length of the groove is the shortest, the depth of the groove is the same as the dummy groove 33D,
The groove 33M for magenta ink is the groove 3 for yellow ink.
The groove length is longer and the groove depth is shallower than 3Y. The groove 33C for cyan ink has a longer groove length and the groove depth is shallower than the groove 33M for magenta ink. The groove 33K has a longer groove length than the groove 33C for cyan ink and is equal to the length of the dummy groove 33D, and the depth of the groove is shallower.

Each of the grooves 33D, 33Y, 3 thus formed
Electrode patterns 34a are formed on the side walls and bottom surfaces of 3M, 33C, 33K by electroless plating, and lead electrodes extend from the rear ends of the grooves 33D, 33Y, 33M, 33C, 33K to the upper surface of the piezoelectric member 31. The pattern 34b is formed. The top portion of the side wall separating each groove and the formation of the lead electrode pattern 34b are formed by separating the portion where the plating layer is to be left from and the portion where the plating layer is to be removed by using a normal photoetching process.

Next, as shown in FIG. 4, each of the grooves 33Y, 33M, 33
C, 33K, the ink supply holes 35Y, 3
An insulating spacer 36 having 5M, 35C and 35K opened is bonded and fixed. That is, the ink supply holes 35Y, 35
M, 35C, and 35K are respectively corresponding grooves 33Y,
The positions are determined according to the lengths of 33M, 33C, and 33K. Even if the ink supply hole 35Y for yellow ink is located at the front, the ink supply hole 3 for magenta ink
5M is located next to the ink supply hole 35C for cyan ink, and at the rear is located an ink supply hole 35K for black ink.

The spacer 36 is made of, for example, an insulating substrate such as zirconia having a thickness of about 50 μm. After patterning ink supply holes at predetermined positions on the insulating substrate by a photoresist layer, holes are formed by a sand plast method. Process. Note that the drilling may be performed by laser processing. Also, using a metal plate as the spacer 36,
An ink supply hole may be formed in this metal plate by etching, and then an insulating process such as an oxide film may be performed.

Next, as shown in FIG.
A top plate 38 having a yellow ink supply path 37Y, a magenta ink supply path 37M, a cyan ink supply path 37C, and a black ink supply path 37K formed thereon is bonded and fixed. At this time, the yellow ink supply path 37Y is located above the yellow ink supply hole 35Y, the magenta ink supply path 37M is located above the magenta ink supply hole 35M, and the cyan ink supply path The supply path 37C is located above the ink supply hole 35C for the cyan ink, and
K is located above the ink supply hole 35K for the black ink.

Next, as shown in FIG.
An orifice plate 39 is adhered to the opening at the tip of each of D, 33Y, 33M, 33C, and 33K, and the grooves 33Y, 33M, 33C, and 33K are attached to the orifice plate 39.
Corresponding to the positions of the yellow ink discharge ports 40, respectively.
Y, a magenta ink discharge port 40M, a cyan ink discharge port 40C, and a black ink discharge port 40K are provided, thereby forming an ink jet head main body. And
The grooves 33Y, 33M, 33C, and 33K form ink chambers for yellow, magenta, cyan, and black, respectively.

FIG. 7 is a longitudinal sectional view of the ink jet head body shown in FIG. 6 at the portion of the groove 33Y for yellow ink. FIG. 7 shows the positional relationship among the groove 33Y, the ink supply hole 35Y, and the ink supply path 37Y. I have. As shown in FIG. 8, a printed circuit board 4 is provided on the rear end of the lead electrode pattern 34b formed on the piezoelectric member 31 with an anisotropic conductive film 41 interposed therebetween.
2 are fixed by bonding, and a drive IC 43 constituting a head drive circuit is fixed on the printed circuit board 42. The printed circuit board 42 is covered and protected by a circuit cover 44 to form an ink jet head.

FIG. 9 is a perspective view showing the relationship between the rotating direction of the rotary drum 2 and the moving direction of the ink jet head 13. The ink jet head 13 is moved by a reciprocating mechanism 15 by the rotation of the motor unit 16. The rotary drum 2 moves in the direction in which the ink chambers are arranged as shown by the middle arrow, and the rotary drum 2 rotates in the direction orthogonal to the direction in which the ink chambers of the ink jet head 13 are arranged as shown by the arrow in the drawing. The recording paper 5 wound around the rotary drum 2 is also transported in a direction orthogonal to the direction in which the ink chambers of the ink jet head 13 are arranged.

FIG. 10 shows the print elements P1, P2, P3, P of the print head PH by controlling the movement of the print head PH.
4A and 4B are diagrams for explaining a general operation when printing is performed at a density higher than the pitch PT of the print head PH.
By rotating by PT / 4 during one rotation of the rotary drum, printing can be performed on the recording paper SH wound on the rotary drum at a print density four times the pitch of the printing elements. That is, the printing elements P1,
P2, P3, P4,... Print dots D11, D15, D19, D113... On the LN1 line in the first rotation, but substantially PT in the main scanning direction on the LNn line on which the rotary drum makes one rotation. Dots Dn1 and Dn at positions shifted by / 4 pitch
n5, Dn9, Dn13 ... are printed.

In the second rotation, the dots D12,... Are printed on the LN1 line, and the dots Dn2,.
..., and the dot D1 on the LN1 line in the third rotation
Are printed on the LNn line, the dots D14,... Are printed on the LN1 line in the fourth rotation, and the dots Dn4,.
In this manner, printing is performed at a printing density four times the printing element pitch. For example, if the print element pitch is 75 dpi (3
(40 μm), printing by this method results in a printing density of 340 μm / 4 = 85 μm, and a printing density of 300 dpi can be realized.

In this embodiment, color printing is performed in the same manner. However, at least three colors of yellow, magenta, and cyan may be printed in a superimposed manner.
Since the dummy grooves are arranged between the ink jet heads, the moving distance of the ink jet head 13 is larger than that in the above case. For example, each ink ejection port 40Y, 40M, 40C, 40K
In order to print at a density four times the pitch of the ink jet head 13 during printing, the ink jet head 13 is moved to each of the ink ejection ports 40Y, 40M, 40C, and 40K.
Is performed by moving the ink jet head 13 by moving the inkjet head 13 by overlapping the inks of the respective colors.

FIG. 11 shows the structure of a reciprocating mechanism 15 and a motor unit 16. The reciprocating mechanism 15 slidably mounts a table 53 on a pair of guide rails 52 a and 52 b attached to a base 51. The table 53 is held by a pair of stoppers 55 by a pair of springs 54a and 54b.
a and 55b are urged rightward in the figure so as to abut against them, and are adjusted to be in a fixed position in a normal state. The motor unit 16 fixes a linear motor 57 to a frame 56, and causes the reciprocating rod 58 to protrude and retract by the rotation of the motor 57 to move the table 53 left and right in the drawing against the urging forces of the springs 54a and 54b. It is configured to control.

The amount of ink ejected from the ink chamber changes depending on the length, depth, width, drive voltage and the like of the groove. In FIG.
As shown in (a) and (b), the depth of the groove is L1, the width is L2,
The distance between adjacent grooves is L3, the thickness of the piezoelectric member 31 is L4,
Let L5 be the thickness of the piezoelectric member 32 and L6 be the length of the groove (the length from the end of the groove to the end of the ink supply hole).

For example, the groove depth L1 is 400 μm, the groove width L2 is 80 μm, and the distance L3 between adjacent grooves is 90 μm.
m, the thickness L4 of the piezoelectric member 31 is 200 μm,
13 is 1.1 mm, the groove length L6 is 10 mm, and a driving voltage of a rectangular wave having a frequency of 2 KHz and a voltage value of ± V as shown in FIG. The case where voltage is applied will be described. Note that, of the driving voltages, + V
Contributes to expanding the ink chamber and replenishing ink from the ink supply holes, and -V contributes to contracting the ink chamber and discharging ink from the ink discharge port.

For example, assuming that a driving voltage having a voltage value of ± 10 V is applied, -10 which contributes to contraction of the ink chamber.
The relationship between the pulse width T of V and the volume of ink ejected from the ink ejection port is as shown in FIG. 13B. For example, when the pulse width T is 8 μm, the ink ejection volume is 30 p.
1 (picoliter) and the pulse width T is 12 μm, the ink ejection volume is 50 pl.

When the drive voltage ± V is changed, the relationship between the drive voltage and the volume of ink ejected from the ink ejection port is as shown in FIG. 13C. For example,
When the drive voltage is ± 10 V, the ink ejection volume is 40 pl. When the depth L1 of the groove is changed, the relationship between the depth of the groove and the ink ejection volume is as shown in FIG. For example, when the groove depth L1 is 400 μm, the ink ejection volume is 50 pl. When the width L2 of the groove is changed, the relationship between the width of the groove and the ink ejection volume is as shown in FIG. When the length L6 of the groove is changed, the relationship between the length of the groove and the ink ejection volume is as shown in FIG. 13 (f). From the above results, it can be seen that the ink ejection volume, that is, the ink ejection amount from the ink ejection port can be adjusted by changing the depth, length, width, and drive voltage of the groove. Of these, the width of the groove changes the pitch between the ink ejection ports, and it is not appropriate to change this.

In this embodiment, the grooves forming the ink chambers in the top plate 38 are formed so that the yellow, magenta, cyan, and black ink supply paths 37Y, 37M, 37C, and 37K can be formed in parallel without overlapping. Since the lengths are made different, the depth of each groove is made different in order to adjust the variation of the ink discharge amount due to this. That is, the depth of the shortest yellow ink groove 33Y is made the deepest, the longest black ink groove 33K is made the shortest, and the second longest is next to the yellow ink groove 33Y. The depth of the groove 33M for the magenta ink is made shallower than the groove 33Y for the yellow ink, and the groove 33 for the cyan ink which is the next longer than the groove 33M for the magenta ink.
The depth of C is made shallower than the groove 33M for magenta ink so that the ink ejection amounts from the yellow, magenta, cyan, and black ink chambers are substantially uniform.
For example, as an example, the length of the groove 33Y for yellow ink is 10 mm, the depth is 480 μm, the length of the groove 33M for magenta ink is 12 mm, and the depth is 440 μm.
The length of the groove 33C for cyan ink is 14 mm and the depth is 4
And the length of the black ink groove 33K is 1
6 mm and a depth of 360 μm.

The ink jet head 13 is of a share mode type, in which a drive voltage is applied between an electrode of an ink chamber to perform ink discharge and an electrode of an adjacent ink chamber to perform ink discharge. The ink is discharged by deforming the side wall of the ink chamber to expand the ink chamber and then contracting the ink chamber. For this reason, if the lengths of the adjacent ink chambers are different, it affects the deformation of the side wall of the ink chamber where the ink is to be ejected, and the ink ejection amount varies. In order to solve this, a dummy groove 33D is required adjacent to each of the yellow, magenta, cyan, and black ink chambers.

Next, driving of the ink jet head 13 will be described. For example, as the drive voltage, a voltage value as shown in FIG. 14 is VSS2 → VDD → VSS1 (where VDD> V
SS2> VSS1) In the case where ink is ejected from the yellow ink chamber 59Y using a rectangular wave driving voltage that changes as follows, the electrode of the yellow ink chamber 59Y as shown in FIG. 59P, the same voltage V is applied to the electrode 33P provided in the adjacent dummy groove 33D.
Apply SS2. In this state, the potential difference between the two surfaces of the piezoelectric members constituting both side walls of the ink chamber 59Y is zero, so that the ink chamber 59Y is not deformed.

In this state, the electrode 59P of the ink chamber 59Y
When a voltage VDD is applied to the ink chamber 59Y, the piezoelectric members forming both side walls of the ink chamber 59Y are moved to the ink chamber 5 as shown in FIG.
Deform to expand 9Y. Due to this expansion, yellow ink is supplied to the ink chamber 59Y from the yellow ink supply path 37Y through the ink supply hole 35Y. At a predetermined timing thereafter, the electrode 59P of the ink chamber 59Y
When the voltage VSS1 is applied to the piezoelectric element, the piezoelectric members forming both side walls of the ink chamber 59Y are deformed so as to compress the ink chamber 59Y as shown in FIG. By this compression, a predetermined amount of ink is discharged from the ink discharge port 40Y of the ink chamber 59Y. When the application of the driving voltage is completed, the state returns to the original state shown in FIG.

A head driving device for performing such an ink discharging operation on the ink jet head 13 has a configuration shown in FIG. The head driving device stores data to be printed as serial data in a shift register 61 in synchronization with a shift clock. The serial data stored in the shift register 61 corresponds to 4-bit gradation data (16 gradations) for each nozzle, and this 4-bit gradation data is converted into 4-bit latch circuits 621, 622, 623,. Latches are made at 624 and 625, respectively. After being latched, the next data to be printed can be stored in the shift register 61.

Each of the latch circuits 621, 622, 623
, 624, 625 and the 4-bit gradation data latched by the 16to1 selectors 631, 632, 633, 634
, 635 respectively. Each selector 6
The reference numerals 31, 632, 633, 634, and 635 select and output one of 16 separately input timing pulse trains based on the value of the input gradation data.

Then, the selected timing pulse is set to 2b
it sequencers 641, 642, 643, 644, 64
5 respectively. One of the 16 timing pulse trains is non-signal data for non-printing. The remaining 15 lines are 2-bit sequencers 64 1, 64 2, 64 3, and 644 in a sequence and timing such that an appropriate amount of ink is ejected corresponding to each gradation.
, 645 are controlled in advance.

The above-mentioned 2-bit sequencers 64 1 and 64 2
, 643, 644, 645 are "0, 0" from the input timing pulse in synchronization with the sequencer clock,
The data is converted into control timing data B1 and B2 including information on the order and time of the four states “0, 1”, “1, 0”, and “1, 1”. And each of these sequencers 6
The control timing data B1, B2 from 41, 642, 643, 644, 645 are assigned to odd nozzles or even nozzles by a demultiplexer 65 comprising a plurality of AND gates.

That is, the demultiplexer 65
Each of the sequencers 641, 642 is operated by the odd number selection signal ODD.
, 643, 644, 645 from the control timing data B1, B2 corresponding to the odd nozzles.
662, 663, 664, and 665, respectively, and each of the sequencers 641, 641 is supplied by an even selection signal EVEN.
The control timing data B1, B2 from 2, 643, 644, 645 are decoded by decoders 671,
672, 673, 674 and 675, respectively.

The decoders 671, 672, 67 corresponding to the even nozzles when the odd selection signal ODD is inputted.
Decoders 661, 662 corresponding to odd nozzles when 3, 674, 675 and even selection signal EVEN are input.
, 663, 664, 665 are supplied with a signal "0,0".

Each of the decoders 661, 671, 662
, 672, 663, 673, 664, 674,
Drive circuits 681, 682, 683, 684, 664, 675 and 675 are used to drive the drive signals S1, S2, S3 from the yellow, magenta, cyan, and black ink chambers.
685, 686, 687, 688, 689, and 6810, respectively. Further, each of the driving circuits 681 to 6
810 are supplied with voltages VSS1, VSS2 and VDD as drive voltages.

Each of the drive circuits 681 to 6810 includes a corresponding one of the decoders 661, 671, 662, 672, 663, 6
According to drive signals S1, S2, S3 from 73, 664, 674, 665, 675, voltages VSS1, VSS2, VDD are selectively selected for a predetermined time, and yellow, magenta,
The voltage is applied to the electrodes formed in the cyan and black ink chambers. Each of the dummy grooves 33
A fixed voltage VSS2 is applied to the D electrode.

In such a configuration, a plurality of grooves are formed in parallel on the substrate on which the piezoelectric members 31 and 32 are adhered as the ink jet head 13, and the grooves are closed by an orifice plate 39 and a top plate 38 to form a plurality of inks. A share mode type head having a chamber is used. In this head, a spacer 36 is interposed between the substrate and the top plate 38 so that the lengths of the respective grooves corresponding to yellow, magenta, cyan, and black are different. The ink supply holes 35Y, 35M, 35C, and 35K for yellow, magenta, cyan, and black are provided on the spacer 36 at positions corresponding to the lengths of the grooves.
Is opened, and the ink supply holes 35Y, 35
M, 35C, and 35K are provided with ink supply paths 37Y, 37M, 37C, and 37K for supplying yellow, magenta, cyan, and black inks, respectively. , The color printing can be realized with one share mode type inkjet head. Thereby, the configuration of the head can be downsized. Also,
Since only one head is used, there is no need to adjust the positional deviation between the heads.

In the case of the share mode type ink jet head 13, if the length of the groove forming the ink chamber is different, the amount of ink to be ejected is not uniform even if operated at the same drive voltage. The depth of the groove is adjusted according to the length so that the amount of ink to be ejected is uniform, so that when operated at the same drive voltage, the amount of ink ejected is approximately the same, which results in the quality of color printing. Can be improved.

In this embodiment, the ink ejection amount is made uniform by changing the depth of the groove in accordance with the length of the groove.
As can be seen from the graph of FIG. 13C, the ink discharge amount can be varied by changing the drive voltage. Therefore, by changing the voltage value of the drive voltage applied according to the length of the groove, each ink chamber can be changed. The amount of ink ejected from the ink can be made uniform. Even in this case, the quality of color printing can be improved.

FIG. 17 shows a partial circuit configuration of a head driving device for realizing this.
The drive voltages VDD, VSS1, and VSS2 supplied to 1, 682, 683, 684, 685, 686,... Are respectively yellow drive voltages VDD (Y), VSS1 (Y), VSS2 (Y) and magenta drive voltages. VDD (M), VSS1 (M), VSS2 (M) and cyan drive voltage VDD (C), VSS1 (C), VSS2 (C) and black drive voltage VDD (K), VSS1 (K), VSS2 (K)
Drive circuits 681 and 685 for driving the yellow ink chamber by driving the yellow drive voltages VDD (Y), VSS1 (Y) and VSS2 (Y).
,..., And drive voltages VDD (M), VSS1 for magenta
(M) and VSS2 (M) are supplied to driving circuits 682, 686,... For driving the magenta ink chamber, and a driving voltage V for cyan is supplied.
DD (C), VSS1 (C), and VSS2 (C) are supplied to drive circuits 683,... For driving the cyan ink chamber, and drive voltages VDD (K), VSS1 (K), and VSS2 (K) for black are supplied. Are supplied to the driving circuits 684,... For driving the black ink chambers, so that the driving voltage can be varied for each color. That is,
It is possible to change the value of the driving voltage to be applied according to the length of the groove.

Further, as can be seen from the graph shown in FIG. 13B, the ink ejection amount can be varied by changing the pulse width T for determining the application time of the negative drive voltage VSS1. Therefore, when the depth of the groove is changed according to the length of the groove or when the voltage value of the drive voltage is changed according to the length of the groove, the pulse width T of the drive voltage is further increased. With a configuration that can be adjusted,
The adjustment of the pulse width T can be used for fine adjustment of the ink ejection amount, whereby the adjustment for equalizing the ink ejection amount from each ink chamber can be performed more accurately, and the color printing quality can be further improved. Become.

In the above-described embodiment, ink chambers for discharging four color inks of yellow, magenta, cyan, and black are periodically arranged in one share mode type ink jet head via dummy grooves. Was mentioned, but is not necessarily limited to this.
For example, two share mode type ink jet heads are provided side by side, and ink chambers for discharging two colors of yellow and magenta inks are periodically arranged via dummy grooves between the two ink jet heads. Ink chambers for discharging the color inks are periodically arranged via dummy grooves between the two ink jet heads, and the two ink jet heads are moved and controlled in synchronization with the rotation of the rotary drum, and color printing is performed by superimposing ink dots of each color. With this configuration, the moving distance of the head can be reduced to half of that in the above-described embodiment, the head configuration becomes slightly larger, and adjustment between the two heads is required, but the printing speed is approximately doubled. It is suitable for high-speed color printing. In this case, the adjustment between the heads is two wells, and the adjustment is simple.

In the above-described embodiment, the dummy grooves are interposed between the ink chambers of the respective colors. However, the present invention is not limited to this. If it can be adjusted by the value, the depth of the groove, or the pulse width T of the drive voltage, the dummy groove can be eliminated, and the density of the pitch of the ink discharge ports can be doubled.

Further, in the above-described embodiment, a rotating drum for rotating and transporting the recording paper in one direction is used as a means for transporting the recording paper. However, the present invention is not limited to this, and a belt may be hung between a pair of rollers. The recording paper may be adsorbed onto the belt using the delivered conveying means, the recording paper may be reciprocated with respect to the ink jet head, and the ink jet head may be controlled to perform color printing.

[0059]

As described above, according to the first to fourth aspects of the present invention, in the case where color printing is performed using a share mode type ink jet head, the overall structure of the head can be reduced in size, and the positional deviation between the heads can be reduced. Adjustment is unnecessary or simple.

Further, according to the second and third aspects of the present invention, the amount of ink of each color to be discharged can be made uniform, and the print quality can be improved.

According to the fourth aspect of the present invention, the amount of ink of each color to be ejected can be made more uniform, and the printing quality can be further improved.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an entire printer showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining a manufacturing process of the inkjet head according to the embodiment.

FIG. 3 is a perspective view showing a configuration of a groove of the inkjet head according to the embodiment.

FIG. 4 is a perspective view showing a configuration of a spacer of the inkjet head according to the embodiment.

FIG. 5 is a perspective view showing a configuration of a top plate of the inkjet head according to the embodiment.

FIG. 6 is a perspective view showing the appearance of the inkjet head main body according to the embodiment.

FIG. 7 is a vertical cross-sectional view showing a configuration of the ink jet head body in the embodiment.

FIG. 8 is a perspective view showing the appearance of the entire inkjet head according to the embodiment.

FIG. 9 is a perspective view showing the relationship between the rotation direction of the rotary drum and the movement direction of the inkjet head in the embodiment.

FIG. 10 is a diagram for explaining a general operation when performing high-density printing using a share mode type inkjet head.

FIG. 11 is a diagram showing a configuration of a reciprocating mechanism and a motor unit in the embodiment.

FIG. 12 is a diagram showing a dimensional relationship of each part of the inkjet head according to the embodiment.

FIG. 13 is a diagram for explaining each element that varies the volume of ink ejected from each ink chamber of the inkjet head according to the embodiment.

FIG. 14 is a diagram showing a drive voltage waveform applied to electrodes of each ink chamber of the inkjet head according to the embodiment.

FIG. 15 is a diagram for explaining an ink ejection operation of the ink chamber of the inkjet head according to the embodiment.

FIG. 16 is a block diagram showing a circuit configuration of a head driving device for driving the inkjet head according to the embodiment.

FIG. 17 is a partial circuit configuration diagram showing another embodiment of a head driving device for driving an ink jet head.

[Explanation of symbols]

 2 rotary drum 5 recording paper 13 inkjet head 15 reciprocating mechanism 16 motor unit 33Y, 33M, 33C, 33K, 33D groove 35Y, 35M, 35C, 35K ink supply hole 36 spacer 37Y, 37M 37C, 37K: ink supply path 38: top plate

Claims (4)

[Claims] 1. A U-shaped elongated groove having a front end opened and a rear end closed on a piezoelectric member is formed in parallel, and a top plate is provided above each of the grooves with a spacer interposed therebetween. And a plurality of rectangular ink chambers formed by providing ink supply holes in the spacer at the upper end of the rear end, and a plurality of inks used in each of the ink chambers are periodically arranged in a predetermined order. An ink-jet head which is housed so as to be disposed, and displaces a piezoelectric member constituting a side wall by application of a driving voltage, thereby deforming an ink chamber to discharge ink from the ink discharge port, Movement control means for controlling movement in the direction in which the chambers are arranged; recording medium transport means for transporting the recording medium in a direction orthogonal to the direction in which the ink chambers of the ink jet head are arranged; and printing. An ink chamber drive control means for controlling the movement of the ink jet head by the movement control means and the deformation and control of each ink chamber of the ink jet head while the recording medium is conveyed by the recording medium conveyance means; Forming the ink supply paths for the number of ink colors to be used to supply the common ink to the ink supply holes of the same ink color on the top plate while varying the length of the groove in accordance with the color of the ink to be stored. The movement control means, the recording medium conveyance means, and the ink chamber drive control means move the ink jet head so as to print a dot row on the recording medium in the conveyance direction and overlap the ink dots of each color at the same position. Control, conveyance of the recording medium, and deformation drive control of each ink chamber of the inkjet head. Color inkjet printer and performs been. 2. A U-shaped long plurality of grooves having a front end opened and a rear end closed on a piezoelectric member are formed in parallel, and a top plate is provided above each of the grooves with a spacer interposed therebetween. And a plurality of rectangular ink chambers formed by providing ink supply holes in the spacer at the upper end of the rear end, and a plurality of inks used in each of the ink chambers are periodically arranged in a predetermined order. An ink-jet head which is housed so as to be disposed, and displaces a piezoelectric member constituting a side wall by application of a driving voltage, thereby deforming an ink chamber to discharge ink from the ink discharge port, Movement control means for controlling movement in the direction in which the chambers are arranged; recording medium transport means for transporting the recording medium in a direction orthogonal to the direction in which the ink chambers of the ink jet head are arranged; and printing. An ink chamber drive control means for controlling the movement of the ink jet head by the movement control means and the deformation and control of each ink chamber of the ink jet head while the recording medium is conveyed by the recording medium conveyance means; Forming the ink supply paths for the number of ink colors to be used to supply the common ink to the ink supply holes of the same ink color on the top plate while varying the length of the groove in accordance with the color of the ink to be stored. And adjusting the depth of the groove in accordance with the length of the groove so that the ink ejection amount from each of the ink chambers becomes substantially the same, wherein the movement control means, the recording medium transport means, and the ink chamber drive control means, A dot row is printed on the recording medium in the transport direction, and the ink jet heads are arranged such that the ink dots of each color overlap at the same position. Movement control, the conveyance of the recording medium, a color ink jet printer and performing deformation driving control of each ink chamber of the ink jet head each. 3. A plurality of long U-shaped grooves having a front end opened and a rear end closed on the piezoelectric member are formed in parallel, and a top plate is provided above each of the grooves with a spacer interposed therebetween. And a plurality of rectangular ink chambers formed by providing ink supply holes in the spacer at the upper end of the rear end, and a plurality of inks used in each of the ink chambers are periodically arranged in a predetermined order. An ink-jet head which is housed so as to be disposed, and displaces a piezoelectric member constituting a side wall by application of a driving voltage, thereby deforming an ink chamber to discharge ink from the ink discharge port, Movement control means for controlling movement in the direction in which the chambers are arranged; recording medium transport means for transporting the recording medium in a direction orthogonal to the direction in which the ink chambers of the ink jet head are arranged; and printing. An ink chamber drive control means for controlling the movement of the ink jet head by the movement control means and the deformation and control of each ink chamber of the ink jet head while the recording medium is conveyed by the recording medium conveyance means; Forming the ink supply paths for the number of ink colors to be used to supply the common ink to the ink supply holes of the same ink color on the top plate while varying the length of the groove in accordance with the color of the ink to be stored. And adjusting the drive voltage value applied to the piezoelectric member according to the length of the groove so that the ink ejection amount from each of the ink chambers becomes substantially the same, wherein the movement control means, the recording medium transport means, and the ink chamber The drive control means prints a dot row in the transport direction on the recording medium and causes the ink dots of each color to overlap at the same position. Color inkjet printer and performing movement control of the ink-jet head, the conveyance of the recording medium, the deformation driving control of each ink chamber of the inkjet head, respectively. 4. The color ink jet printer according to claim 2, wherein the amount of ink discharged from each ink chamber is finely adjusted by adjusting the pulse width of the drive voltage applied to the piezoelectric member.