JPH03295658A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To raise the velocity of printing operation by providing ink jet printing heads being overlapped with each other and movable in the overlap direction, and by discharging ink droplets to different positions from nozzles of each of the ink jet printing heads while moving in the overlap direction. CONSTITUTION:A nozzle plate 21a having a plurality of nozzles 20a formed in a line and a piezo-electric actuator 22a are joined and constitute an ink jet printing head 23a. A nozzle plate 21b having a plurality of nozzles 20b formed in a line and a piezo-electric actuator 22b are joined and constitute an ink jet printing head 23b. The ink jet printing heads 23a and 23b are overlapped with each other. The overlap body comprising the tow ink jet heads 23a and 23b moves in the overlap direction as indicated by an arrow 'B' and makes a printing on a printing paper 24. Thus, the ink jet printing heads being overlapped with each other are moved in the overlap direction and discharge the printing ink to different positions, thereby making it possible to raise the velocity of the printing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus having a plurality of nozzles.

[Prior Art] Inkjet recording devices are often used as output devices for electronic devices such as word processors and personal computers.

FIG. 17 is an explanatory diagram showing the configuration of nozzles of an inkjet recording head used in this type of inkjet recording apparatus and ink dots formed by these nozzles.

As shown in the figure, in the inkjet recording head IO, a plurality of nozzles J1, J2, J3, J4, .
They are arranged in a line in the direction perpendicular to the printing direction shown by .

An example of ink dots formed by moving and ejecting ink from the inkjet recording head IO having one row of nozzles is shown on the right side of the figure. That is,
1 column is a, b.

Ink dots made of cSd... are formed in multiple rows. Characters are created by the matrix arrangement of these ink dots.
Numbers and symbols are printed (see similar patent application US Pat. No. 4,459,601).

Further, Japanese Patent Laid-Open No. 11353/1983 proposes an easy-to-manufacture ink jet recording head in which a nozzle plate having a plurality of nozzles arranged in two rows and a recording head main body are integrated.

Further, Japanese Patent Laid-Open No. 62-238756 proposes printing by joining a plurality of ink jet recording heads having nozzles arranged in a row in parallel.

[Problems to be Solved by the Invention] When performing high-speed printing using this type of inkjet recording head, it is necessary to increase the moving speed of the inkjet recording head in the printing direction and shorten the ink jetting interval. However, it takes a considerable amount of time to suck up the ink from the ink chamber to the nozzle and eject it from the nozzle. For this reason, the interval at which ink is ejected, that is, the frequency of the signal voltage, cannot follow the moving speed of the inkjet recording head, making it difficult to increase the printing speed.

Therefore, an object of the present invention is to provide an inkjet recording device with high printing speed.

[Means for Solving the Problem] According to the present invention, the above-mentioned object is achieved by recording a plurality of inkjet recordings, each of which has a plurality of nozzles arranged in one row, and which are superimposed on each other in a direction perpendicular to the direction in which the nozzles are arranged. This is achieved by comprising a head and a control means for ejecting ink from the nozzles of each inkjet recording head while moving the overlapping inkjet recording heads in the superimposing direction so that the printing position of each inkjet recording head is different from each other. Ru.

[Operation] The control means of the inkjet recording apparatus moves the superimposed inkjet recording heads in the superimposing direction and prints ink droplets ejected from the nozzles of each inkjet recording head at different positions.

[Examples] The inkjet recording apparatus according to the present invention will be explained in detail below using examples.

FIG. 2 is a perspective view of an inkjet recording head of an inkjet recording apparatus as an embodiment of the present invention.

As shown in the figure, a nozzle plate 21a in which a plurality of nozzles 2Qa are formed in one row and a piezoelectric actuator 22a
A first inkjet recording head 23a is formed by joining them together, and a second inkjet recording head 23b is formed by joining the piezoelectric actuator 22b to a nozzle plate 21b in which a plurality of nozzles 20b are formed in one row. is formed. These inkjet recording heads 238 and 23b are overlapped with each other.

These two inkjet recording heads 23g and 23b
The superimposing body prints on the paper 24 while moving in the superimposing direction shown by arrow B.

3 is an exploded perspective view of the inkjet recording head 23a or 23a shown in FIG. 2. FIG. However, for simplicity, the number of nozzles is two.

As shown in the figure, a roughly comb-shaped piezoelectric actuator 26 is provided on a substrate 25.
A GND (ground) electrode 27 is provided above the electrode 6 . A cover block 29 is provided on the GND electrode 27 with a diaphragm 28 in between.

The drive circuit 30 applies a signal voltage to one of the signal electrodes 31 in response to an external signal. Therefore, the teeth 32 of the corresponding piezoelectric actuator 26 are displaced up and down, that is, in the direction of pushing the diaphragm 28, due to the piezoelectric longitudinal displacement effect, and the corresponding part of the diaphragm 28 is pushed up, and the corresponding part of the diaphragm 28 is pushed up. The ink is ejected from the ink chamber 34 to the outside through the nozzle 35, and is printed on paper or the like.

4 is a plan view of the cover block 29 shown in FIG. 3, and FIG. 5 is a side view of the cover block 29 shown in FIG. 3.

As shown in FIG. 4, the cover block 29 has 12 nozzles 135 and an ink chamber 13 communicating with these nozzles.
4, an ink reservoir 136, and an ink supply port 137 are formed.

The cover block 29 shown in FIGS. 4 and 5 is made of photosensitive glass, such as PEG3 (a homogeneous glass ceramic with no pores in which fine lithium disilicate crystals are precipitated) or a silicon wafer. It is formed by etching.

FIG. 6 is an explanatory diagram for explaining the piezoelectric longitudinal displacement effect utilized in the piezoelectric actuator shown in FIG. 3.

The piezoelectric bodies are stacked alternately in opposite directions. Every other electrode is connected.

When a voltage is applied to the electrodes, the piezoelectric body moves in the direction of arrows D1 and D2.
deform in the direction. This phenomenon is the piezoelectric longitudinal displacement effect.

FIG. 7 is a block diagram of the inkjet recording apparatus of this embodiment.

As shown in the figure, a clock generator 38 is connected to a control circuit 39 and a synchronization circuit 40. This control circuit 39 includes a ROM 41 (read only memory), RA
M42 (random access memory), I10 port 4
3 and an output port 44 via a pass line 45. The output port 44 is connected to a synchronization circuit 40, and the synchronization circuit 40 is connected to a head driver 46. The head driver 46 is connected to the ink shed recording heads 23a and 23b.

Clock generator 38 generates clock pulses and supplies them to each circuit. For example, a crystal oscillation circuit is used to generate clock pulses, but this is not limited to PLL.
A (phase-locked loop) circuit may also be used.

The control circuit 39 generally controls the present inkjet recording apparatus, and preferably uses a microprocessor. This control circuit 39 executes print data input/output and conversion processing according to the system program stored in the ROM 41.

The RAM 42 is a memory that stores print data input from the I10 boat 43.

The head driver 46 supplies print data from the output port 44 to the piezoelectric actuators of each inkjet recording head 23a and 23b.

FIG. 8 is a block diagram showing in detail the circuitry shown in FIG. 7 including the output port, synchronization circuit 40, and head driver 46.

As shown in the figure, the output port 44 is composed of a plurality of (two in the figure) output ports 44a and 44b. Note that the number of output ports 44a and 44b is two, but
The number is not limited to this, and the number may increase with the number of inkjet recording heads. A pass line 45 connects these output ports 44
g and 44b, respectively. The first output port 44a has, for example, an even number column (2n%
n" 1.2,...) are input in parallel. The second output port 44b has odd numbered columns (2n"
-1, n=1.2, . . . ) print data are input in parallel.

As shown by the circles in Figure 9, the print data consists of two pieces of data in even and odd columns arranged alternately, and the number of rows in each column (the number of vertical circles in the figure). corresponds to the number of nozzles in each inkjet recording head.

The output terminals of the first output port 44a are each connected to one input terminal of a first group of AND gates 48a (upper part of the figure) consisting of n two-person AND gates.

The output terminals of the second output port are each connected to one input terminal of a second group of AND gates 48b (center of the figure) consisting of n two-person AND gates.

The synchronous circuit has one delay counter 49 and two counters 5.
It is composed of 0 and 51 and 2n two-man gates.

Clock pulses are delayed by counter 49 and two counters 5
0 and 51 are supplied to input terminals CK.

LOAD pulse is delayed by counter 49 and two counters 5
0 and 51 are supplied to input terminals LD.

The ENABLE pulse is input to the input terminal EN of the delay counter 49.
2 and the input terminal EN of the counter 5o, respectively. The output terminal RCO of the delay counter 49 is connected to the counter 5.
1 and the input terminal of the inverter 52. The output terminal of this inverter 52 is connected to the ENI terminal of the delay counter 49. counter 51
The output terminal RCO of is connected to the other input terminal of the first group of anime game h 48g. counter 5o
The output terminals RCO of are respectively connected to the other input terminals of the second group of AND gates 48b. The output terminals of the AND gates 48a and 48b of the first and second AND gate groups are connected to the input terminals of the head driver 46, respectively.

The first output port 44a outputs 2n columns of print data to the first output port 44a.
output to the group AND gate 48a and the second output port 4
4b outputs 2n-1 columns of print data to the second group of AND gates 48b.

When the ENABLE pulse is input to the input terminal EN2 of the delay counter 49, the delay counter 49 supplies a pulse to the input terminal of the counter 51 from its output terminal RCO after a predetermined period has elapsed.

The counter 51 supplies a pulse signal (timing pulse, see FIG. 10(A)) of logic level "1" to the input terminal of each AND gate 4Bg of the first group at a period t1 in response to the ENABLE pulse.

The counter 51 supplies a pulse signal of logic level "1" to the input terminal of each AND gate 48b of the second AND gate group in response to a pulse from the output terminal RCO of the delay counter 49 (timing pulse, FIG. (B)). That is, the counter 51 delays each AND gate 48b of the second AND gate group by a predetermined period t2 from the counter 50.
A pulse signal of logic level “1” is input to the input terminal of
Supplied with

Each AND gate 48a of the first and second AND gate groups
and 48b are provided to head driver 46 when the signals from the RCO output terminals of counters 50 and 51 are at the rlJ logic level.

Next, the operation of such an inkjet recording apparatus will be explained as follows.
This will be explained with reference to FIGS. 7 and 8, which are explanatory diagrams for explaining the nozzles of the inkjet recording head shown in the figure and the state of ink ejection.

As shown in FIG. 7, print data in digital format is stored in the RAM 42 from the outside via the I10 port 43 and the data bus 45. The print data stored in the RAM 42 is transferred to the output port 44 via the data bus 45 according to instructions from the control circuit 39 .

Even-numbered column data in the print data is sent to the first output port 4.
4a, and odd-numbered column data in the print data is transferred to the second output port 44b.

Assume that 2n-1 columns of print data are being transferred to the second output port 44b. LO supplied from control circuit 39
In response to the AD pulse, ENABLE pulse, and clock pulse, the timing pulse Pi from the output terminal RCO of the counter 50 is applied to each ant gate of the second AND gate group.
b (FIG. 7(A)). At this time, the nozzle N1 of the first inkjet recording head 23a
, N2, .
CI, (1+'') is injected at the position (FIG. 1).

On the other hand, a timing pulse P4 is supplied from the output terminal RCO of the delay counter 49 to one input terminal of each AND gate 48a of the first AND gate group after a period t2 from the timing pulse Pi (see FIG. 7 (A, B). )). Second
Since 2n columns of print data are transferred to the other input terminal of each AND gate 48b of the AND gate group, the second
Nozzles M1 and M2 of the inkjet recording head 23b of
Ink is ejected from , . At this time, since the inkjet recording heads 23a and 23b are moving at a constant speed in the direction of arrow B in the figure, al, t)1 of column X1
, CI, dl, . . . and are printed at positions a2, bl, c2, d2, . . . of a different ink dot row X2 (FIG. 1). Note that the inkjet recording head 23a
The movements of 23b and 23b are performed by a mechanical controller (not shown) according to instructions from a control circuit.

The timing pulse P2 from the output terminal RCO of the counter 50 is supplied to the input terminal of each AND gate 48b of the second AND gate group after a period t1 from the timing pulse P1 (FIG. 7(A)). At this time, 2n+1 columns of print data are being transferred to the second output port 44b. At this time, ink from the nozzles N1, N2, .
It is injected at the position ``'' (Figure 1).

Similarly, a timing pulse P5 is supplied from the output terminal RCO of the delay counter 49 to one input terminal of each AND gate 48a of the first AND gate group after a period t1 from the timing pulse P4 (FIG. 7 CB)). Since the print data of 2n+2 columns is transferred to the other input terminal of each AND gate 48b of the second AND gate group, the nozzles ML M2 of the second inkjet recording head 23b,
..., the ink is C4, b4, C4, C4 of column X4,
... is injected at the position (Fig. 1). Repeat this below.

As a result, ink droplets are ejected onto the paper etc. at intervals of 11 from the nozzles N1, N2, . . . of the head 23a, and the nozzles M1, M2, . - Ink droplets are also ejected onto the same sheet of paper etc. at intervals of 11.

Ink dot rows printed by ink droplets ejected from each nozzle of the first inkjet recording head 23a and ink droplets ejected from each nozzle of the second inkjet recording head 23b do not overlap and are printed at intervals of 11/2. be done.

Therefore, the first and second inkjet recording heads 23a
The ink dots ejected from the nozzles 23b and 23b are equally spaced.

tl is the time during which the inkjet recording heads 23a and 23b have moved by a distance of 11. tl is inkjet recording head 23! and 23b is the time it takes to move by a distance of 12+11/2.

In the figure, 11>12, but if the distance between the first and second inkjet recording heads 23a and 23b is 12, then tl<tl.

Also, when the number of inkjet recording heads is n, the distance between each inkjet recording head is 11 ・k/
Since there is a deviation of n+12* (k=1.2.3.), it is necessary to drive the inkjet recording head at a timing specific to the inkjet recording head.

FIG. 11 is an exploded perspective view of another configuration example of the inkjet recording head used in this embodiment.

As shown in the figure, a roughly comb-shaped piezoelectric actuator 56 is provided on a substrate 55.
A cover block 58 having a plurality of (two in the figure) ink chambers 57 is attached on top of the ink chamber 6 .

A nozzle plate 60 in which a plurality of nozzles 59 (two in the figure) are formed is provided on the front surface of the piezoelectric actuator 56 and the cover block 58, and an inkjet recording head 61 is provided.
is configured. Electrodes 63 are provided on both upper and lower surfaces of each tooth portion 62 of the piezoelectric actuator 56, and are connected to a drive circuit (not shown).

FIG. 12 is a sectional view taken along line II of the inkjet recording head 61 shown in FIG. 11.

When the drive circuit applies a signal voltage to one of the electrodes 63 in response to an external signal, the tooth portion 62 of the corresponding piezoelectric actuator 56 is displaced in the vertical direction (in the direction of arrow D3 in the figure) due to the piezoelectric longitudinal displacement effect. As a result, ink is ejected to the outside through a nozzle 59 communicating with the ink chamber 57, and printing is performed on paper or the like.

FIG. 13 is an exploded perspective view of still another configuration example of the inkjet recording head used in this embodiment.

As shown in the figure, a substrate 66 is formed in which a plurality of nozzles 64 (six in the figure) and a plurality of ink chambers 65 each communicating with the nozzles 64 are formed in parallel and integrally at a predetermined interval. There is. A comb-shaped piezoelectric actuator 67 is mounted on this substrate 66 , and each tooth portion 68 of this piezoelectric actuator 67 is inserted into each ink chamber 65 . Electrodes 6 are provided on both upper and lower surfaces of each tooth portion 68 of the piezoelectric actuator 67.
9 are provided and are connected to a drive circuit 70 on the piezoelectric actuator 67 via a wiring pattern 71. A plate 73 provided with a plurality of ink introduction lowers 2 is bonded to the front part (left side in the figure) of the substrate 66. An ink tank 75 having an ink supply lower 4 provided on its upper surface is mounted on the plate 73. This ink tank 7
The ink supply lower 4 of No. 5 communicates with the ink supply lower 4 and each ink chamber 65 internally.

When a signal from the outside (not shown) is supplied to the drive circuit 70, the drive circuit 70 supplies a signal voltage to the electrode 69. When a signal voltage is supplied to the electrode 69 of the tooth 68, the tooth 68 displaces the ink chamber 65 in a direction opposite to the ejection direction due to the piezoelectric lateral displacement effect. When this signal voltage is released, the teeth press the ink chamber 65 in the ejection direction. As a result, the ink in the ink chamber 65 is ejected from the nozzle 64 to the outside.

FIG. 14 is an explanatory diagram for explaining the piezoelectric lateral displacement effect.

As shown in the figure, electrodes are bonded to both sides of a piezoelectric body polarized in the direction of arrow P. The piezoelectric body is polarized in the stacking direction, and when a voltage is applied to the electrode, the piezoelectric body is displaced in the direction of arrow D4. When the voltage applied to the electrode is released, this piezoelectric body is displaced in the opposite direction of arrow D4. This phenomenon is the piezoelectric lateral displacement effect.

Further, other effects that can be used in the piezoelectric actuator include a unimorph effect and a bimorph effect, and either of these effects may be used to press the ink chamber.

FIG. 15 is an explanatory diagram for explaining the unimorph effect.

As shown in the figure, a piezoelectric body polarized in the direction of arrow P is sandwiched between electrodes, and this bonded body and an elastic body are laminated. The piezoelectric body is polarized in the stacking direction, and one end of the stack is fixed. When a voltage is applied to the electrodes of this laminate, the piezoelectric body is displaced in the direction of arrow D6. However, since it is joined to the elastic body, the laminate as a whole is shaped like arrow D.
Displaced in the direction of 7. This phenomenon is the unimorph effect.

FIG. 16 is an explanatory diagram for explaining the bimorph effect.

As shown in the figure, 2 is polarized in the direction indicated by the arrow P.
Two piezoelectric bodies and three electrodes are alternately stacked on each other. One end of the piezoelectric body is fixed. The polarization directions of the two piezoelectric bodies are opposite to each other, and a negative potential is applied to the electrodes on both sides, and a positive potential is applied to the intermediate electrode.

When a voltage is applied to the electrodes of the piezoelectric body, the piezoelectric body on the right side of the figure is displaced in the direction of arrow DB, and the piezoelectric body on the left side is displaced in the direction of arrow A. However, since these piezoelectric bodies are joined to each other, the laminate as a whole is displaced in the direction of the arrow DIO. This phenomenon is the bimorph effect.

Further, in this embodiment, ink is alternately ejected from the nozzles of two inkjet recording heads, but the invention is not limited to this, and ink may be ejected simultaneously to print at different positions.

From the above, it is possible to increase the printing speed by moving a plurality of overlapping inkjet recording heads in the overlapping direction and printing at different positions, so that the moving speed of the head is not limited by the ink jetting frequency. Can be done.

[Effects of the Invention] As described in detail above, according to the present invention, a plurality of inkjet recording heads each having a plurality of nozzles arranged in a row and superimposed on each other in a direction perpendicular to the direction in which the nozzles are arranged. and a control means for ejecting ink from the nozzles of each inkjet recording head while moving the superimposed inkjet recording heads in the superimposing direction so that the printing position of each inkjet recording head is different from each other, so that the printing speed can be controlled. It can be done quickly.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the nozzles of an inkjet recording head and the ink ejection state, FIG. 2 is a perspective view of an inkjet recording head of an inkjet recording apparatus as an embodiment of the present invention, and FIG. 4 is a plan view of the cover block shown in FIG. 3, FIG. 5 is a side view of the cover block shown in FIG. 3, and FIG. 6 is a side view of the cover block shown in FIG. An explanatory diagram for explaining the piezoelectric longitudinal displacement effect used in the piezoelectric actuator shown in the figure, FIG. 7 is a block diagram of the inkjet recording apparatus of this embodiment, and FIG. 8 is an output port shown in FIG. 7. , a block diagram showing in detail the circuits up to the synchronization circuit and the head driver, FIG. 9 is a diagram showing print data, FIG. 10 is a timing pulse, and FIG. 11 is another configuration of the inkjet recording head used in this example. Example exploded perspective view,
FIG. 12 is a sectional view taken along line II of the inkjet recording head shown in FIG. 11, FIG. 13 is an exploded perspective view of still another configuration example of the inkjet recording head used in this embodiment, and FIG. 14 is a piezoelectric An explanatory diagram for explaining the lateral displacement effect, FIG. 15 is an explanatory diagram for explaining the bimorph effect, FIG. 16 is an explanatory diagram for explaining the bimorph effect, and FIG. 17 is an explanatory diagram for explaining the bimorph effect. FIG. 2 is an explanatory diagram showing the configuration of nozzles of an inkjet recording head used and ink dots formed by these nozzles. 21... Nozzle plate, 22... Piezoelectric actuator, 23... Inkjet recording head, 24... Paper, 38... Clock generator, 39... Control circuit, 40
...Synchronous circuit, 41...ROM, 42
...RAM, 43 ... I10 port, 44 ... Output port, 45 ... Pass line, 46 ... Head driver, 49.・・・
...Delay counter, 50.51...Counter. Figure 3 Figure 1 Figure 2 Figure 8 Figure 11 Figure 12 Figure 16 Figure $17

Claims (1)

[Claims] Each of them has a plurality of nozzles arranged in a row, a plurality of inkjet recording heads are superimposed on each other in a direction perpendicular to the nozzle arrangement direction, and the superimposition is performed such that the printing position of each inkjet recording head is different from each other. an inkjet recording apparatus comprising: a control means for ejecting ink from the nozzles of each inkjet recording head while moving the lower part of the inkjet recording head in the superimposing direction.