JPH0939254A - Ink-jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be able to print continuous monochromatic lines on a record carrier by nozzles of a single row. SOLUTION: The ink jet recorder comprises a recording head having a group of nozzles 19 substantially linearly arranged to deliver ink droplets 45, plate-like charging electrodes 25 so disposed before the nozzles 19 as to deflect the droplets by an electrostatic field by applying charge to the droplets and a deflector having deflecting electrodes 27. Further, the recorder comprises a transfer unit having a cooperation roller and a motor for transferring a record carrier 11 to the nozzles 19. Piezoelectric actuators 15, 16 are provided, and the nozzles 19 so communicate with a pressure chamber 17 as to deliver the droplets 45 only at the time of applying predetermined signal to the actuators. The droplets 45 are deflected by the deflector in a certain angle range to the direction substantially parallel to the group of nozzles 19. Further, a deflection controller for controlling the deflection angle of the droplets 45 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a group of nozzles arranged in a substantially straight line for ejecting ink drops, and in front of each nozzle for applying an electric charge to the ejected ink drops to deflect them by the action of static electricity. The present invention relates to an ink jet recording apparatus, which comprises a recording head having a deflecting means arranged therein, and further comprises a transfer means for transferring a record carrier so as to move the recording carrier in a lateral direction of a group of nozzles with a surface facing the nozzle.

[0002]

2. Description of the Prior Art A device of this kind is reissued in US Pat. No. 28219.
Known from the issue. This known device is a continuous inkjet system that delivers a continuous stream of ink drops from each nozzle. The deflection means is configured as a binary deflection system. The ink drop passes through the deflecting means without deflecting, or deflects at a predetermined angle. The undeflected ink drops travel on the record carrier and the deflected ink drops are blocked and returned to the sump. Therefore, this deflecting means acts as a selection device for selecting the ink droplets adhering to the record carrier.

This known device comprises multiple rows of parallel, equidistant nozzles. For structural reasons, the distance between adjacent nozzles in a row is relatively large. Therefore, gaps are formed between the dots formed on the record carrier by the ink drops delivered by the adjacent nozzles. The rows are staggered laterally in order to allow the device to print a continuous line extending over the entire width of the record carrier. If the ink droplets are ejected from the nozzles of the first row appropriately delayed from the ejection of the ink droplets of the nozzles of the second row arranged upstream of the nozzles of the first row in the transport direction of the record carrier, Ink droplets from the first row of nozzles and the second row of nozzles deposit on a common line on the record carrier. If a sufficient number of nozzle rows is provided and the delay between the ejection of ink droplets from different nozzle rows is controlled very accurately, a continuous line of ink droplets can be deposited on the record carrier. However, it is obvious that this device becomes large due to the large number of nozzle rows. It also has the drawback of requiring a highly accurate and expensive control mechanism.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording device which is capable of printing continuous monochromatic lines on a record carrier with only a single row of nozzles.

[0005]

To achieve this object, the ink jet recording apparatus of the present invention is constructed as a recording apparatus for adhering ink droplets in response to a request, and only when a predetermined signal is applied to the actuator means. Each nozzle is in communication with a pressure chamber associated with the actuator means for delivering an ink drop, and the deflection means is configured to deflect the ink drop over a range of angles in a direction generally parallel to the group of nozzles. Is provided with a deflection control means for controlling the deflection angle of.

Recording devices for depositing ink drops in response to demand are known, for example from US Pat. No. 4,599,628 and EP 0516188. Typically, these devices have a relatively small printhead that is movable across the width of the record carrier, as disclosed in US Pat. No. 4,491,854, for example. Drives requiring such movement add significantly to the weight of the device, and the time required for the movement makes the device relatively slow. Since the present invention deposits ink drops from a single nozzle at multiple locations on a record carrier, electrostatic deflection of the ink drops can be used to provide a relatively wide portion of the record carrier (eg, 1 mm size). It is based on the idea that each nozzle can print. This allows
It makes it possible to print continuously extending lines over the entire width of the record carrier by means of only a single group of nozzles and also by a static recording head. If each nozzle covers about 1 mm of the width of the record carrier, a group of 210 nozzles can sufficiently cover the width of the paper sheet (the size of A4).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the device of the present invention is a plate-shaped charging electrode extending parallel to a group of nozzles, which has a hole arranged in front of each nozzle. , A deflection electrode provided in front of the charging electrode in the vicinity of each hole is provided in the deflection means, and a charging voltage generator for supplying a charging voltage to the charging electrode and a deflection voltage generator for supplying a deflection voltage to the deflection electrode are provided. It is characterized in that it is provided in the deflection control means. After leaving the nozzle, the ink drop first passes through the hole of the charging electrode, and depending on the voltage supplied by the charging voltage generator, the ink drop receives an electrostatic charge through this hole. The charged ink droplets then pass between the deflection electrodes and are deflected at a predetermined angle. This deflection angle is determined, among other things, by the charge of the ink drop, the voltage between the deflection electrodes, and the velocity of the drop. For a given speed,
The deflection angle can be controlled by changing the charging voltage, the deflection voltage, or both. A particularly simple variant of this embodiment is that one of the charging voltage generator and the deflection voltage generator is arranged to supply a voltage which varies as a function of time, while the other voltage generator is substantially It is characterized in that it is configured to supply a constant voltage. This variant requires that only one of the voltage generators is of the controllable type.

In a second embodiment of the present invention, the deflection means comprises a plurality of pairs of deflection electrodes, one pair of deflection electrodes is arranged in front of each nozzle, and both sides of the nozzle are seen in the direction of a group of nozzles. A pair of deflection electrodes is arranged in each of the electrodes, each deflection electrode is formed of a conductive plate having a first portion and a second portion, the first portion extends in a direction away from the nozzle, and the second portion includes a group of nozzles. Deflecting the voltage generating means arranged close to each other so as to supply the first voltage pulse to the first portion of each pair of deflection electrodes and to supply the second voltage pulse to the second portion of each pair of deflection electrodes. The control means is provided so that the first voltage pulse and the second voltage pulse have the same polarity and the same amplitude and start at the same time.
The time required for the first voltage pulse is different from the time required for the second voltage pulse. This embodiment is particularly simple from a structural point of view, since it does not have a separate charging electrode.
The combination of the first voltage pulse and the second voltage pulse helps to charge and deflect the ink drop. 1
Preferably, the distance between the first parts of the pair of deflection electrodes is greater than the distance between the second parts. Since the second part of the deflection electrode is in close proximity to each other and to the nozzle, the process of charging the ejected ink drop is very effective. The large distance between the first portions provides the space required for ink droplet movement caused by deflection, which is parallel to the group of nozzles. Various constructions are possible to achieve the difference in distance between the first part and the second part.

In the first structure, the second portion of each deflecting electrode extends substantially at right angles to the first portion, the first portion extends substantially perpendicular to the direction of arrangement of the group of nozzles, and the second portion A portion extending substantially parallel to the arrangement direction of the group of nozzles, and a second portion of each deflection electrode forming a pair extending so as to approach another deflection electrode forming a pair. . The second structure is characterized in that the deflection electrode has a curved shape, and the second portion thereof extends substantially at right angles to the group of nozzles.

The recording apparatus of the present invention can be modified for multicolor printing. An embodiment adapted for this purpose is that the recording head comprises a plurality of groups of nozzles arranged in a straight line in a substantially parallel manner, such that different groups of nozzles eject ink droplets of different colors. Characterize. If the nozzles of each group communicate with the pressure chambers that are supplied with ink of one of the four basic colors (usually magenta, cyan, yellow, and black), then the nozzles of the four groups will be on the record carrier. Is enough to get a full color print. In order to ensure that ink drops of different colors that contribute to the coloring of the same part of the image to be formed are deposited on the same line on the record carrier, it is possible to introduce a suitable delay between the delivery of ink drops from different nozzle groups. Needless to say.

A modification of the recording apparatus for multicolor printing is that the first group of nozzles and the second group of nozzles, which are arranged substantially linearly, are provided in the recording head, and the adjacent nozzles of the first group have the first nozzles. And a second group of adjacent nozzles configured to deliver ink drops having a third color and a fourth color, respectively. The first color, the second color, the third color, and the fourth color are different from each other. It has been found that by deflecting ink drops, two colors can be deposited by a single group of nozzles. The different color ink drops delivered by adjacent nozzles are deflected to cause these colors to overlap on the record carrier. As a result, the four basic colors can be attached using only the two groups of nozzles. The multicolor recording apparatus having the above features is very simple and lightweight. The above-described aspects and other aspects of the present invention should be apparent from the examples described below.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 diagrammatically illustrates an ink jet device with the minimum pieces required to provide sufficient background for an understanding of the present invention. The apparatus comprises a recording head 1, which comprises a group of substantially linear nozzles for ejecting ink drops. This group of nozzles is not shown in FIG. This group of nozzles is arranged parallel to the chain line 3. These nozzles face the standby station 5 in order to keep the recording head in proper condition even when the device is not in use. An ink container 6 is provided for supplying ink to the recording head 1. The device further comprises transfer means in the form of a pair of cooperating rollers 7 driven by an electric motor 9. These rollers 7 serve to transport the record carrier 11, which is usually a paper sheet, so that the record carrier 11 is between the recording head 1 and the standby action station 5 as indicated by the arrow 13 in the direction transverse to the group of nozzles. Moving. When the record carrier 11 is thus transferred, the surface of the record carrier (the surface facing downward in FIG. 1) faces the nozzle. A control unit 14 is provided to control the operation of this device.

FIG. 2 is a cross-sectional view of the first embodiment of the recording head 1 taken along a line parallel to the chain line 3 in FIG. The recording head comprises a plurality of piezoelectric actuator elements 15 provided in an actuator plate 16, the elements comprising a plurality of alternating layers of ceramic piezoelectric material and electrode layers (not shown). Recesses 17 forming pressure chambers are provided in the actuator plate 16 so that the actuator element 15 cooperates with each pressure chamber. The pressure chamber 17 is connected to the ink container 6 (see FIG. 1) by an ink supply system (not shown). A detailed description of this type of recording head can be found in the pending patent application (PHN 15,079), which is incorporated herein by reference. Each pressure chamber communicates with the nozzle 19 provided on the nozzle plate 21 that covers one side of the pressure chamber. As described above, the nozzles 19 arranged in a substantially linear group extending parallel to the chain line 13 are arranged.
The opposite side of the pressure chamber 17 is covered with a back plate 23. When a suitable voltage is applied to one of the actuator elements 15, the associated pressure chamber 17 contracts and the ink drop is associated with the associated nozzle 19.
Sent from. This type of system is reissued US Pat. No. 28
In contrast to the continuous jet system that produces a continuous stream of drops as disclosed in No. 219, it is known as a demand responsive drop system that delivers drops on demand.

Deflection means are placed in front of each nozzle 19 to ensure that the ink drops delivered by the nozzles pass through these deflection means. In the embodiment shown in FIG. 2, the deflection means comprises a plate-shaped charging electrode 25 and a deflection electrode 27 arranged in front of this charging electrode. This charging electrode 25 is connected to a group of nozzles 1
The charging electrode 25 is provided with a hole 29 extending parallel to the nozzle 9 and directed to the front of each nozzle. The deflection electrode 27 is also plate-shaped. These deflection electrodes 27 extend substantially perpendicular to the charging electrode 25. In this embodiment, the deflection electrode 27 is arranged in the center between the adjacent holes 29 forming each pair. The charging electrode 25 and the deflection electrode 27 are electrically conductive. The deflecting electrodes 27 are electrically separated by the insulating bottom portion 31. The charging electrode 25 and the deflection electrode 27 can be formed by a metal plate, for example, a nickel plate. In this case, the deflection electrode 27 is mechanically connected to the charging electrode 25 by an electrically insulating adhesive forming the insulating bottom 31. Alternatively, the charging electrode 25 and the deflecting electrode 27 may be formed as a single structure from an electrically insulating material such as glass, the bottom 31 being removed except for this single part, for example by vapor deposition of a suitable metal in a vacuum. Cover the structure with a conductive film.

FIG. 3 is a top view of the recording head shown in FIG. One of the pressure chambers 17 is shown by a broken line. The charging electrode 25 covers the nozzle plate 21 in the vicinity of the nozzle 19, and the nozzle 19 is visible through the hole 29. The deflection electrode 27 is arranged near the hole.

FIG. 4 is a block diagram of the control unit 14 of the recording apparatus shown in FIG. The control unit 14 comprises a central control unit 33, which comprises a microprocessor, a motor control means 35 for controlling the electric motor 9, a delivery control means 37 for controlling the delivery of ink drops,
And the deflection control means 39 for controlling the deflection of the ejected ink droplets are controlled by this microprocessor. In the embodiment shown in FIGS. 2 and 3, the deflection control means 39 includes a charging voltage generator 41 for supplying the charging voltage to the charging electrode 25 and a deflection voltage generator for supplying the deflection voltage to the deflecting electrode 27. 43 and. The central control unit 33 integrates the functions of the control means 35, 37, 39 and deposits the ink drops on the surface of the record carrier 11 at desired positions.

The operation of this device is as follows. When an ink drop is ejected from the nozzle 19, it passes through the associated hole 29 in the charging electrode 25. The output terminal of the charging voltage generator 41 is electrically connected between the ink supply system (for example, the ink container 6 or the nozzle plate 21) and the charging electrode 25. Therefore, the charging electrode 25 is maintained at a predetermined voltage with respect to the ink in the pressure chamber 17. As a result, the ink droplets passing through the holes 29 acquire an electrostatic charge according to the charging voltage supplied by the charging voltage generator 41. At each time, the deflection voltage generator 4 is so arranged that the two deflection electrodes on either side of the hole 29 are connected to different terminals of the deflection voltage generator.
The terminal 3 is connected to the deflection electrode 27. Therefore, as shown by the signs plus (+) and minus (-) in FIG. 2, the sequential deflection electrodes 27 have opposite polarities. As a result, a deflection electrostatic field is generated between each pair of deflection electrodes 27. This deflection electrostatic field is oriented parallel to the lines of the group of nozzles 19.
This electrostatic deflection field causes the charged ink drop 45 to follow a curved trajectory, as shown by the two broken lines 46 and 47 in FIG.

As a result of the different polarities of the successive deflection electrodes 27, ink drops ejected from adjacent nozzles 19 will be deflected in opposite directions. Since the charging voltage and the magnitude of the deflection voltage are the same for all ink drops, the deflection angles are also the same. By varying the charging voltage, the deflection voltage, or both, the deflection angle of all ink drops can be controlled. To make controlling the device as simple as possible,
It is preferable to keep one of these voltages constant. If the two trajectories are curved so as to approach each other, the voltage of the other trajectories is changed so that the trajectories 46 and 47 of adjacent trajectories intersect with the record carrier 11 at the maximum deflection. Controls the deflection angle of the ink drop. In this way, the entire width of the record carrier 11 can be covered with ink drops. At a predetermined deflection angle, the ink droplet 45 ejected from the nozzle 19 is deposited on the record carrier. The position is a position shifted by a predetermined distance parallel to the line 3 with respect to the position directly facing the nozzle. If it is desired to bring the ink drop closer to such a position, the central control unit 33 causes the delivery control unit to provide a signal to the associated actuator element 15. Also, if this is not desired, then no drops are delivered.

FIG. 5 is a diagram showing an example of charging voltage as a function of time. As previously mentioned, this varying charging voltage is preferably associated with a constant deflection voltage. As an alternative, the deflection voltage may be changed as shown in FIG. 5 to keep the charging voltage constant. The charging voltage V starts at the maximum negative value −V _max and increases _stepwise to the maximum positive value + V _max . Each stage corresponds to a distinct deflection angle. In this example, the number of stages is 10, and the time to perform all stages is T. The charging voltage is then -V in a single stage
Decrease to _max and start the next cycle. Therefore, the charging voltage resembles a sawtooth voltage. It is also possible to reduce the charging voltage in multiple stages during the time T, in which case the charging voltage resembles a triangular wave voltage. Instead of changing the charging voltage in a plurality of stages, it may be changed continuously, for example, linearly. In that case, the deflection angle is also changed continuously. The change in charging voltage between −V _max and + V _max corresponds to a change in the deflection angle of the ink drop between the two extremes, ie over the entire range of possible values. During the time interval T, the central control unit 33 prevents the motor control means 35 from energizing the motor 9. That is, the transfer of the record carrier 11 is interrupted. Therefore, during this time interval the nozzle 19
All ink droplets ejected by the ink deposit on the record carrier in a single line parallel to line 3.

As mentioned above, it is desirable to connect the output terminal of the charging voltage generator 41 between the ink supply system and the charging electrode 25. It is preferable to ground the ink supply system and the record carrier 11 for stable operation. The record carrier may be contacted with a grounded metal brush (not shown) that acts as a drain electrode for electrostatic charge. The side of the record carrier facing away from the recording head 1 may be provided with a backing electrode in the form of a conductive surface (for example part of the waiting station 5), to which a predetermined voltage is applied. In this way, the drops have a high initial velocity, which is favorable and advantageous for good drop delivery. The voltage applied to the backing electrode has the effect of slowing the drop, so that the drop does not move too fast in the deflection field, but deflects properly.

In the first embodiment described above, the deflection means associated with each pair of adjacent nozzles 19 share a common deflection electrode 21. As a result, the ink drops delivered by adjacent nozzles 19 are simultaneously deflected in opposite directions. Also,
It is also possible to provide two deflection electrodes 27 between each pair of nozzles 19, these two deflection electrodes being electrically isolated from each other and electrically connected to different terminals of the charging voltage generator 41. To be done. In this case, the ink droplets sent by the adjacent nozzles 19 are simultaneously deflected in the same direction.

6A and 6B are sectional views of a part of the recording head of the second embodiment of the present invention. FIG. 6A shows the first
FIG. 6B shows a second variant. The structure of the ink droplet delivery unit of the recording head is similar to that of the first embodiment shown in FIG. For simplicity, only the nozzle plate 21 of this structure is shown in FIGS. 6 and 6B.

In the second embodiment, instead of the charging electrode 25 and the deflecting electrode 27 of the first embodiment, an electrode structure composed of a plurality of pairs of deflecting electrodes 48 is used. A pair of deflection electrodes 4
8 is placed in front of each nozzle 19 so that one of the pair of deflection electrodes is located to the left of the nozzle opening and the other is to the right, as shown in FIGS. 6A and 6B. In other words,
Two pairs of deflection electrodes 48 are located on both sides of the nozzle 19 when viewed in the direction of the group of nozzles. Each deflection electrode 48 comprises a conductive plate having a first portion 49 extending in a direction away from the nozzle 19 and a second portion 50 near the group of nozzles. These conductive plates can be, for example, metal plates or metallized insulating plates.

The distance between the first portions 49 of the pair of deflection electrodes 48 is arranged so as to be larger than the distance between the second portions 50. As a result, the second portion 50 defines a narrow slit 51 between the pair of second portions,
The ejected ink droplet passes through the slit 51. While the ink droplets pass through the slit 51, the deflection electrode 48 is maintained at a predetermined potential with respect to the ink supply system or the nozzle plate 21. Therefore, the ink drop acquires an electrostatic charge of a magnitude corresponding to this voltage. When an ink drop passes through the slit 51,
A predetermined voltage is applied between the pair of two electrodes associated with the common nozzle 19. As a result, a deflection electrostatic field is generated between the electrodes 48. The charged ink drops are the first portion 49 of the deflection electrode.
When moving between, the generated electrostatic field deflects the charged ink droplets. This means that the deflection electrode 48 has two functions. That is, adding an electrostatic charge to the ink drops delivered by the nozzle 19 and deflecting the charged ink drops over a controlled deflection angle.

In the modification shown in FIG. 6A, the second portion 50 of the deflecting electrode 48 extends approximately at right angles to the first portion 49. The first portion 49 extends perpendicular to the row of nozzles 19 and the second portion 50 extends parallel to the row of nozzles.
In this modification, the deflection electrode 48 has an L-shaped cross section, and the second portion 50 of each deflection electrode forming a pair extends toward the second portion of the other deflection electrode of the same pair. In the variation shown in FIG. 6B, the deflection electrode 48 has a curved shape,
This curved shape substantially follows the path of the ink drop having the maximum deflection angle. The second portion 50 extends substantially perpendicular to the row of nozzles 19 in the group.

Since it is necessary to be able to apply a voltage between the two electrodes forming a pair, all the electrodes on the left side of the nozzle 19 are connected to the first common terminal and all the electrodes on the right side of the nozzle are connected to the second common terminal. Connect to. This connection is shown in FIG. 7, which is a plan view of the variation shown in FIG. 6B. In FIG. 7, the first terminal and the second terminal are indicated by reference numerals 53 and 55, respectively. Each terminal 53,
55, with the electrodes connected to it, forms a comb structure, which is arranged alternately. The first terminal 53 and the second terminal 55 are connected to the terminals of the voltage generator which is a part of the deflection control means 39 shown in FIG.

FIG. 8 is a diagram showing an example of the voltage applied to the terminals 53 and 55. In this example, the first voltage V ₁ is applied to the first terminal 53 and the second voltage V ₂ is applied to the second terminal 55.
The first voltage V ₁ comprises a series of first voltage pulses, namely the two pulses 57, 59 shown in FIG. The time required for the first voltage pulse in sequence changes in a predetermined state. FIG. 8 shows that the first pulse (57) of the first voltage pulse starts at time t ₁ , t
_Ending at ₃ , the second pulse (59) begins at t ₄ and t ₆
, Which indicates that the time interval t ₆ -t ₄ is longer than the time interval t ₃ -t ₁ . In an actual embodiment, the time required for the first voltage pulse is the minimum value t ₂ −t ₁ (= t ₅ −t ₄ ).
To a predetermined maximum value (not shown). Second
The voltage V ₂ has a series of second voltage pulses such as 61, 63. Like the second voltage pulse has a _{t 2 -t 1 (= t 5} -t 4) of the same duration. Therefore, the corresponding first voltage pulse and the second voltage pulse start at the same time and generally have different durations (as described above,
The voltage pulse of the first voltage has the same duration as the voltage pulse of the second voltage). The amplitude A and the polarity of the first voltage pulse and the second voltage pulse are the same.

At time t ₁ , the first terminal 53 connected to the deflection electrode 48 to the left of the associated nozzle 19 is first
A voltage pulse 57 is applied and a second voltage pulse 61 is applied to the second terminal 55 connected to the deflection electrode to the right of the corresponding nozzle. Since the amplitudes A and the polarities of the two pulses 57 and 61 are the same, during the time interval t ₂ -t ₁ , the nozzle 19
The deflection electrodes 48 on both sides of the same have the same potential with respect to the ink supply system of the nozzle plate 21. At the start of this time interval, the ejected ink drops will be deflected by the deflection electrode 4 during this time interval.
8 passes through the second portion 50 and receives an electrostatic charge. Time t ₂
Then, the second pulse 61 ends, and the first pulse 57 continues with the same amplitude. As a result, an electrostatic field is generated here between the two deflection electrodes 48 on both sides of the nozzle 19. Due to this electrostatic field, the charged ink droplet is deflected in a direction away from the electrode 48 connected to the first terminal 53.

While the ink picker is passing between the first portions 49 of the deflection electrode 48, the deflection of the charged ink droplets occurs. This deflection angle is the amplitude A of the first pulse 57, the second pulse 61, the second pulse 61
Duration t ₂ -t ₁ of the pulse 61, and a second pulse 61
Time required for the first pulse 57, which is longer than the required time t ₃ −t
Determined by ₂ . Therefore, the first way to control the deflection angle is to change the duration of the first pulse 57.
In the example shown in FIG. 8, this is done, ie the next pulse 59 is made longer than the pulse 57. First
After the maximum duration of the pulse is reached, it is necessary to apply the first voltage V ₁ to the second terminal 55 and the second voltage V ₂ to the first terminal 53, which causes the ink drops to deflect in the opposite direction. Another way to control the deflection angle is to change the duration of the second pulse 61 to control the electrostatic charge applied to the ink drop. This method uses the fact that the deflection angle increases with increasing charge for the same deflection field. Yet another method of controlling the deflection angle is to change the amplitude A of the first pulse and the second pulse.

FIG. 9 is a plan view of the recording head for the multicolor ink jet recording apparatus. This drawing is shown in FIG.
Similar to that of FIG. This recording head has a first group of nozzles 65 and a second group of nozzles 67 which are linearly arranged substantially in parallel. The first group of nozzles 65 is composed of two types of nozzles, a first type nozzle 19a and a second type nozzle 19b. Nozzles 65 of the first group are formed by alternately arranging nozzles of the first type and nozzles of the second type. Similarly, the third type nozzles 19c and the fourth type nozzles 19d are alternately arranged to form the second group of nozzles 67. The difference between the four nozzle types is that they each communicate with a pressure chamber that is connected to an ink supply system filled with different color inks.
In this way, different types of nozzles are adapted to deliver different colors of ink. For example, the nozzle 19
a, 19b, 19c, and 19d deliver magenta, cyan, black, and yellow inks, respectively. By appropriately selecting the pitch of the nozzles and the maximum angle of deflection of the ink drops, the ink drops are delivered by the nozzles so that they adhere to points on the record carrier 11 located opposite two adjacent nozzles. Deflected ink drops. Thus, ink drops delivered by one of the first type nozzles 19a can be deposited in front of each one of the two adjacent second type nozzles 19b and at each intermediate position.

Therefore, this recording head is composed of the recording carrier 1.
The ink droplets of the two colors sent by the nozzles 19a and 19b of the first group 65 are deposited over the entire width of No. 1. Similarly, the ink droplets ejected by the nozzles 19c and 19d of the second group 67 can be attached to the entire width of the record carrier 11. As shown in FIG. 1, the nozzle group 65,
The record carrier 11 is transported in a direction perpendicular to the direction 67. Therefore, if the ejection of the ink droplets by the nozzles 19c and 19d of the second group 67 is delayed by an appropriate interval with respect to the ejection of the ink droplets by the nozzles 19a and 19b of the first group 65, they will be on the same line extending in the width of the record carrier 11. Ink drops from all four types of nozzles adhere. The required delay amount can be calculated from the speed of the record carrier 11 and the distance between the two types of nozzle groups 65 and 67. The central control unit 33 can be programmed to control this delay. It is clear that by using the recording head shown in FIG. 8, a very compact and inexpensive multicolor inkjet recording device can be obtained. Modifications of the illustrated configuration are possible. For example, three or four types of nozzle groups can be used and each nozzle group is used for each ink color.

FIG. 10 is a top view of a slightly modified printhead similar to the printhead shown in FIG. In this recording head, the nozzles 19 are slightly staggered. These nozzles 19 form a group of linearly arranged nozzles extending as zigzag lines having the general direction indicated by the line 69. There is an advantage that the pitch of a group of nozzles can be made smaller than that when the nozzles are arranged in strict accordance with the straight line as in FIG. Therefore, the recording speed of the device can be increased, or the ink droplets ejected by the adjacent nozzles 19 can be attached to the same position on the recording carrier 11, so that the overlapping portion can be incorporated. Of course, in order to obtain a straight line on the record carrier 11, it is necessary to add an appropriate delay to the ejection of ink drops from the various nozzles 19. A group of nozzles 65 of the recording head shown in FIG.
It is also possible to use a zigzag arrangement of nozzles for each one of the 67.

[Brief description of drawings]

FIG. 1 is a diagrammatic view of an embodiment of an inkjet recording apparatus of the present invention.

2 is a partial cross-sectional view of a first embodiment of a recording head of the apparatus shown in FIG.

FIG. 3 is a drawing seen from above the recording head shown in FIG.

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

5 is a diagram showing an example of a voltage applied to an electrode of the recording head shown in FIG.

FIG. 6A is a partial cross-sectional view of a second embodiment of the recording head shown in FIG. 6B is a partial cross-sectional view of a modification of the recording head of FIG. 6A.

FIG. 7 is a drawing seen from above the recording head of FIG. 6B.

FIG. 8 is a diagram showing an example of voltage applied to electrodes of the recording head shown in FIGS. 6A and 6B.

9 is a drawing of the recording head of the apparatus shown in FIG. 1 as viewed from above in a third embodiment. FIG.

FIG. 10 is a plan view of a modified example of the recording head of the apparatus shown in FIG.

[Explanation of symbols]

 1 Recording Head 5 Standby Action Station 6 Ink Container 7 Cooperating Roller 9 Electric Motor 11 Recording Carrier, Paper Sheet 14 Control Unit 15 Piezoelectric Actuator Element 16 Actuator Plate 17 Recess, Pressure Chamber 19 Nozzle 21 Nozzle Plate 23 Back Plate 25 Plate Charging Electrode 27 Deflection electrode 29 Hole 31 Insulation bottom 33 Central control unit 35 Electric motor control means 37 Delivery control means 39 Deflection control means 41 Charging voltage generator 43 Deflection voltage generator 45 Charged ink droplet 48 Deflection electrode 49 First part 50 Second part 51 Slit 53 First Terminal 55 Second Terminal 57, 59 First Voltage Pulse 61, 63 Second Voltage Pulse 65 First Group Nozzle 67 Second Group Nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Johann Frederick Diksmann Netherlands 6136 Arse Sittard Lakeswech Noord 281 (72) Inventor Michel Haryon Versink Netherlands 6136 Arse Sittard Lakeswech Noord 281

Claims (12)

[Claims] 1. A group of nozzles (19) arranged in a substantially straight line for ejecting ink drops (45), and a nozzle (19) for each of the nozzles for adding an electric charge to the ejected ink drops and deflecting them by the action of static electricity. Deflection means (25, 2, 2) placed in front
7) and a transfer means (7, 9) for transferring the record carrier (11) so as to move in the lateral direction (13) of the group of nozzles with the surface facing the nozzles. In an ink jet recording apparatus comprising
The recording device is configured as a recording device for adhering ink droplets in response to a request, and the actuator means (15) is configured to send out the ink droplets (45) only when a predetermined signal is applied to the actuator means (15). Each nozzle (19) is in communication with an associated pressure chamber (17) and the deflection means (25, 27) is arranged to deflect ink drops over a range of angles in a direction substantially parallel to the group of nozzles.
And an deflection control means (39) for controlling the deflection angle of the ink droplet. 2. A plate-shaped charging electrode (25) having a hole (29) arranged in front of each nozzle, which is a plate-shaped charging electrode extending parallel to the group of nozzles (19), A deflection electrode (27) provided in front of the charging electrode near the hole
And a deflection voltage generator (43) for supplying a deflection voltage to the deflection electrode, and a deflection voltage generator (43) for supplying a deflection voltage to the deflection electrode. The inkjet recording device according to claim 1, further comprising: 3. A voltage generator of one of the charging voltage generator (41) and the deflection voltage generator (43) is configured to provide a voltage (V) that varies as a function of time,
The ink jet recording apparatus according to claim 2, wherein the other voltage generator is configured to supply a substantially constant voltage. 4. The deflection means comprises a plurality of pairs of deflection electrodes (4
8), a pair of deflection electrodes (48) is arranged in front of each nozzle (19), and a pair of deflection electrodes is arranged on both sides of the nozzles when viewed in the direction of a group of nozzles. The deflection electrode is composed of a conductive plate having a first portion and a second portion,
The first portion extends away from the nozzles, the second portion (50) is located near the group of nozzles, and a first voltage pulse () is applied to the first portion of each pair of the deflection electrodes. 57) to supply a second voltage pulse (61) to the second portion of the pair of deflection electrodes, the deflection control means (39) is provided with a voltage generator. The second voltage pulse has the same polarity and the same amplitude (A) and starts at the same time, but the time required for the first voltage pulse is different from the time required for the second voltage pulse. Item 2. The inkjet recording device according to item 1. 5. A first portion (49) of a pair of said deflection electrodes.
The ink jet recording apparatus according to claim 4, wherein the distance between the two is larger than the distance between the second portions (50). 6. A second portion (5) of each said deflection electrode (48).
0) extends substantially at right angles to the first portion (49), the first portion (49) extends substantially perpendicular to the arrangement direction of the group of nozzles (19), and the second portion is 7. A deflecting electrode extending substantially parallel to the arrangement direction of a group of nozzles, wherein the second portion of each deflecting electrode forming a pair extends so as to approach another deflecting electrode forming a pair. Item 6. The inkjet recording device according to item 5. 7. The deflection electrode (48) is curved and the second portion (50) thereof is the group of nozzles (19).
The ink jet recording apparatus according to claim 5, wherein the ink jet recording apparatus is extended substantially at a right angle. 8. The inkjet according to any one of claims 4 to 7, characterized in that the deflection control means (39) is provided with means for changing the required time of the first voltage pulse (57). Recording device. 9. The inkjet according to any one of claims 4 to 8, characterized in that the deflection control means (39) is provided with means for changing the required time of the second voltage pulse (61). Recording device. 10. The deflection control means (39) is provided with means for changing the amplitudes of the first voltage pulse (57) and the second voltage pulse (61).
7. The inkjet recording device according to any one of items 7 to 7. 11. The recording head comprises a plurality of groups (65, 69) of nozzles (19a to 19d) arranged in a straight line substantially parallel to each other so that ink droplets of different colors are delivered to the nozzles of different groups. The ink jet recording apparatus according to any one of the preceding claims, characterized in that 12. The recording head is provided with a first group of nozzles and a second group of nozzles that are arranged substantially linearly, and the adjacent nozzles (19a, 19b) of the first group (65) have a first color. And ink droplets having a second color are respectively ejected, and the adjacent nozzles (19c, 19c,
19d) is configured to deliver ink drops having a third color and a fourth color, respectively, the first color, the second color,
The ink jet recording apparatus according to claim 11, wherein the third color and the fourth color are different from each other.