JP2002273878A - Line type ink jet head and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line type ink jet head which can ease mutual interferences between adjacent ink nozzles and between adjacent ink pressure means (actuators), can reduce a positional deviation irregularity of ink nozzles and can improve the printing quality by reducing a printing characteristics irregularity. SOLUTION: A plurality of ink nozzles are arranged linearly by a predetermined pitch to a head chip of each ink jet head. Each of the head chips is arranged on the same substrate in an inclination state in which an ink nozzle arrangement has an angle θ to a linear arrangement direction. Therefore, the plurality of ink nozzles are arranged by an equal pitch smaller than the predetermined pitch with respect to the linear arrangement direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line type ink jet head in which a plurality of ink jet heads are arranged in a line along the entire width of a recording medium, and an on-demand type ink jet recording apparatus provided with the line type ink jet head. It is about.

[0002]

2. Description of the Related Art In an ink-jet recording apparatus for directly ejecting ink droplets from an ink nozzle onto a recording medium such as recording paper for recording, for example, an ink-jet printer, an on-demand method for ejecting ink droplets only when necessary is called an ink-jet method. Since a collection mechanism is not required, it is easy to reduce the cost and size, and can easily cope with colorization.

[0003] Ink jet heads provided in such an ink jet printer can be roughly classified according to a method of ejecting ink droplets.
Three types of electrostatic systems are known. Of these, two main types of ink jet heads for personal printers are the electromechanical conversion method and the electrothermal conversion method. The electromechanical conversion system is a system in which a pressure wave is generated in an ink liquid chamber by displacement of a piezo element, and the ink is pressurized by the pressure wave to eject ink droplets from an ink nozzle. The electrothermal conversion method is a method in which bubbles are generated in an ink liquid chamber by a heater heated to a high temperature in a short time, and the ink is pressurized by volume expansion of the bubbles to eject ink droplets from an ink nozzle. It is.

[0004] On the other hand, in the electrostatic system, an electrostatic force is applied between a vibration plate constituting a bottom surface of an ink liquid chamber and a flat plate electrode facing the vibration plate to displace the vibration plate to apply the ink liquid chamber. In this method, ink droplets are ejected from ink nozzles by the pressure. With respect to this type of electrostatic inkjet head, Japanese Patent Laid-Open No. 2-289351,
Various structures are disclosed in JP-A-5-050601, JP-A-6-071882, and the like. This electrostatic inkjet head has an advantage that it can be manufactured by a wafer process, can be easily made high in density, and can be manufactured in a large number of elements with stable characteristics. In addition, there is an advantage that downsizing is easy because of the planar structure.

[0005] Here, when the ink jet heads of the above-described respective systems are classified according to the printing system for a recording medium (recording paper), two types, a serial system and a line system, are known. The serial system prints one line while reciprocating the inkjet head in the width direction of the recording medium (recording paper), and prints one line.
In this method, printing is continued by feeding one line to a recording medium (recording paper) every time printing of a line is completed. The line system is a system in which one line is simultaneously printed from a plurality of ink nozzles arranged corresponding to the entire width of a recording medium (recording paper), and has an advantage that the printing speed is faster than the serial system.

[0006]

However, in the above-described line system, since a plurality of ink nozzles are arranged over the entire width of a recording medium (recording paper), the pitch between the ink nozzles and the printing characteristics vary. Is larger than the serial method. Further, if at least one of the ejection characteristics of the ink droplets from the ink nozzles arranged over the entire width of the recording medium (recording paper) is lowered, the printing quality is greatly reduced. Accordingly, the line method including a single inkjet head has a problem that the production yield is extremely low and the cost is high. Further, when the pitch between the ink nozzles in both the serial system and the line system is reduced, mutual interference between adjacent ink nozzles and between ink pressurizing means (actuator) becomes a problem.

The present invention solves the problems of the prior art in such a line type ink jet head, and can reduce mutual interference between adjacent ink nozzles and ink pressurizing means (actuator). It is an object of the present invention to provide a line type ink jet head which can reduce variations in ink nozzle misalignment and, as a result, reduce variations in printing characteristics and improve printing quality.

[0008]

As a means for solving the above-mentioned problems, a line type ink jet head according to the present invention is configured such that ink in a plurality of ink liquid chambers is individually pressurized by a pressurizing means, and a plurality of ink nozzles are pressed. In a line-type inkjet head in which a plurality of inkjet heads configured to individually eject ink droplets are arranged in a line, the plurality of ink nozzles are linearly arranged at a predetermined pitch on a head chip of each inkjet head. An inclined state in which the ink nozzle arrangement direction of each head chip forms a certain angle with respect to the line arrangement direction so that these ink nozzles are arranged at the same pitch in the line arrangement direction of the inkjet head. Wherein each head chip is arranged on the same substrate.

In the line type ink jet head according to the present invention, since the ink nozzle arrangement direction of each head chip forms a fixed angle with respect to the line arrangement direction, a plurality of linearly arranged at a predetermined pitch in each head chip. Are arranged in the line arrangement direction at the same pitch smaller than the predetermined pitch. In other words, the arrangement pitch of the plurality of ink nozzles on each head chip can be wider than the required dot formation pitch on the recording medium (recording paper). Therefore, mutual interference between adjacent ink nozzles and between ink pressurizing means (actuators) is reduced.
Variations in the displacement of each ink nozzle are reduced.

In the line type ink jet head according to the present invention, if the head chips are arranged in two rows in a staggered manner on the same substrate, the space between adjacent ink jet heads is widened and the mounting area of each ink jet head is sufficiently increased. Can be taken.

Further, in the line type ink jet head of the present invention, when an electrostatic pressurizing means is provided as the pressurizing means, power consumption can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a line type ink jet head and an ink jet recording apparatus according to the present invention will be described with reference to the drawings. In the drawings to be referred to, FIG. 1 is a perspective view of an ink jet recording apparatus according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the ink jet recording apparatus shown in FIG. 1, and FIG. Schematically shows the structure of a line type ink jet head,
(A) is a plan view thereof, (b) is a plan view shown in FIG.
FIG. 7C is a cross-sectional view taken along line CC of the plan view shown in FIG.

First, an ink jet recording apparatus according to an embodiment having a line type ink jet head according to the present invention will be described with reference to FIGS. In the ink jet recording apparatus according to one embodiment, a printing mechanism 2 and the like are housed inside an apparatus main body 1 and a large number of sheets 3
A paper feed cassette (paper feed tray) 4 capable of loading is mounted so as to be freely inserted and removed from the front side. In addition, a manual tray 5 for manually feeding the paper 3 is mounted to be freely opened. The ink jet recording apparatus takes in the paper 3 fed from the paper feed cassette (paper feed tray) 4 or the manual feed tray 5 and prints the paper 3 by the printing mechanism 2.
After printing the required prints and images, the paper 3 is discharged to a paper discharge tray 6 mounted on the back side of the apparatus main body 1.

The printing mechanism 2 includes a carriage 13 movable in the main scanning direction, an ink jet head 14 mounted on the carriage 13, an ink cartridge 15 for supplying ink to the ink jet head 14, and the like. The printing mechanism 2 includes a main guide rod 1 laid as a guide member on left and right side plates (not shown) of the apparatus main body 1.
The carriage 13 is slidably held in the main scanning direction (in FIG. 2, in a direction perpendicular to the paper surface) by the first guide rod 12 and the first guide rod 12. The carriage 13 includes yellow (Y), cyan (C), magenta (M), and black (B
An inkjet head 14 for ejecting (discharging) ink droplets of each color of K) is mounted. In the inkjet head 14, a plurality of ink nozzles 114 are arranged in a direction crossing the main scanning direction.
Are arranged with the ink droplet ejection direction (ejection direction) facing downward.

Each ink cartridge 15 for supplying ink of each color to the ink jet head 14 is exchangeably mounted on the carriage 13. At the upper part of each ink cartridge 15, an air port communicating with the atmosphere is opened, and at the lower part, a supply port for supplying ink to the ink jet head 14 is opened. Inside the ink cartridge 15, a porous body filled with ink is accommodated. Due to the capillary force of the porous body, the ink supplied to the inkjet head 14 is maintained at a slight negative pressure.

Here, as the ink jet head 14, yellow (Y), cyan (C), magenta (M),
Although a plurality of inkjet heads 14 that eject (discharge) ink droplets of each color of black (BK) are used,
One ink jet head 14 having ink nozzles for ejecting (discharging) ink droplets of each color may be used. As means for pressurizing the ink in the ink liquid chamber of the ink jet head 14, a piezo type in which the ink is pressurized by a vibrating plate constituting a wall surface of the ink liquid chamber by an electromechanical transducer such as a piezoelectric element, or a heating resistor The ink is applied by displacing the diaphragm by electrostatic force between a diaphragm forming the wall surface of the ink liquid chamber and a diaphragm that forms the wall surface of the ink liquid chamber and pressurizing the ink by generating bubbles by the body. Although an electrostatic type for pressing can be used, in the present embodiment, an electrostatic type pressing means is employed.

The carriage 13 is slidably fitted on the main guide rod 11 on the rear side (downstream side in the paper transport direction), and the slave guide rod 1 on the front side (downstream side in the paper transport direction).
2 is slidably mounted. In order to move and scan the carriage 13 in the main scanning direction, a timing belt 20 is stretched between a driving pulley 18 and a driven pulley 19 which are rotationally driven by a main scanning motor 17. The carriage 13 is fixed to the belt 20. The carriage 13 is reciprocated in the main scanning direction together with the timing belt 20 by the forward / reverse rotation of the main scanning motor 17.

On the other hand, in order to transport the paper 3 set in the paper feed cassette 4 to a position immediately below the ink jet head 14, a paper feed roller 21 and a friction pad 22 for separating and feeding the paper 3 from the paper feed cassette 4 are provided. A guide member 23 for guiding the paper 3, a transport roller 24 for inverting and transporting the fed paper 3, a transport roller 25 pressed against the peripheral surface of the transport roller 24, and a transport roller 25. And a tip roller 26 for defining a feed angle of the sheet 3 conveyed from the roller 24 is disposed inside the apparatus main body 1. The transport roller 24 is driven by a sub-scanning motor 27 via a gear train.
Is driven to rotate.

Immediately below the ink jet head 14, a print receiving member 29 for supporting the sheet 3 fed from the transport roller 24 is disposed corresponding to the moving range of the carriage 13 in the main scanning direction. Have been. The paper 3 is located downstream of the printing receiving member 29 in the paper transport direction.
Roller 3 that is driven to rotate to feed the paper in the paper discharge direction.
1 and a spur 32, a paper discharge roller 33 and a spur 34 for sending the paper 3 to the paper discharge tray 6, and guide members 35 and 36 for forming a paper discharge path.

In one embodiment, an ink jet recording apparatus comprises:
By driving the inkjet head 14 according to an image signal while moving the carriage 13, ink droplets are ejected (discharged) to the paper 3 stopped below the inkjet head 14.
To record one line, and after transporting the paper 3 by a predetermined amount,
Record the next line. Then, upon receiving a recording end signal or a signal indicating that the rear end of the sheet 3 has reached the recording area, the recording operation is terminated and the sheet 3 is discharged to the discharge tray 6.

In the ink jet recording apparatus according to one embodiment, a recovery device 37 for recovering the ejection (ejection) failure of the ink jet head 14 is provided at a position outside the recording area on the right end side in the moving direction of the carriage 13. ing. The recovery device 37 includes a cap unit, a suction unit, and a cleaning unit. When the carriage 13 is moved to the recovery device 37 side during standby for printing, the recovery device 37 caps the inkjet head 14 by capping means, keeps the plurality of ink nozzles in a wet state, and ejects the ink nozzles by drying the ink. Discharge) defects are prevented. In addition, the recovery device 37 makes the ink viscosity of all the ink nozzles constant by ejecting the ink to a portion that is not related to the recording, for example, during the recording of the ink jet head 14, thereby stably ejecting (discharging).
Maintain performance.

Here, in the event that an ink droplet ejection (ejection) failure occurs, the recovery device 37 seals each ink nozzle of the ink jet head 14 by capping means, and suctions each ink via a tube by suction means. Bubbles and the like are sucked out together with the ink from the nozzles, and ink, dust, and the like attached to the ink nozzles are removed by the cleaning means, thereby recovering the ejection (ejection) failure of the ink droplets. The ink sucked by the suction means is discharged to a waste ink reservoir (not shown) provided at a lower portion of the apparatus main body 1, and is absorbed and held by an ink absorber in the waste ink reservoir.

Next, a line type ink jet head according to an embodiment of the present invention will be described with reference to FIG. In one embodiment, the line type inkjet head is a single crystal SI.
It is composed of two parts, an electrode substrate 101 composed of a substrate and an ink liquid chamber substrate 108. The electrode substrate 101
N-type or P-type impurity atom is 1E14 / CM3 to 1E1
6 / CM3. Normally, a single-crystal SI substrate with a plane orientation of (100) is used, but there is no problem if a single-crystal SI substrate with a (110) or (111) is used depending on the process. Further, as the substrate material, Pyrex (registered trademark) glass or the like can be used in addition to the single crystal SI substrate.

Ink liquid chamber substrate 1 composed of a single crystal SI substrate
08, a plurality of diaphragms 110 of silicon thin film driven by electrostatic force between the individual electrodes 102 of the electrode substrate 101, and a plurality of ink chambers each of which has a part of a wall surface. The (pressurized liquid chamber) 107, the common liquid chamber 111 for supplying ink to each ink liquid chamber (pressurized liquid chamber) 107, and the flow path connecting the two are formed by a technique such as anisotropic wet etching. Is formed. The diaphragm 110
Are arranged to face the individual electrodes 102 of the electrode substrate 101, respectively.

The individual electrode 102 is an electrode for pulling the diaphragm 110 made of a silicon thin film by electrostatic attraction. As the individual electrode 102, AL, TIN, TISI, or the like can be used. Although not shown, a conductive impurity layer different from the conductivity type of the single crystal SI substrate may be formed to serve as a diffusion electrode.

In FIG. 3C, reference numeral 104 denotes an insulating film formed by a thermal oxidation method, a CVD method, a sputtering method, or the like. By forming the insulating film 104 by photolithography, etching, or the like, the diaphragm 110 is formed.
A gap (gap) is formed between the single crystal SI substrate on which the individual electrodes 102 are formed. This gap spacer
When a voltage is applied to the diaphragm 110 made of a silicon thin film facing the individual electrode 102 through the interface, an electrostatic attraction is generated. The thickness of the insulating film 104 is a design parameter that affects the operating characteristics such as the driving voltage of the inkjet head 14 and is appropriately selected according to the operating specifications of the inkjet head 14.

In FIG. 3B, reference numeral 106 denotes a pad for applying a voltage to the individual electrode 102. Each of the pads 106 is a member for extracting an electrode from the individual electrode 102 formed on the electrode substrate 101 by wire bonding or the like. Etc. Reference numeral 103 denotes an electrode substrate 101
FP that externally applies voltage to pad 106 formed in
This is a pad take-out portion for performing mounting such as C or wire bonding, and is opened to the ink liquid chamber substrate 108.

Further, in FIG.
Denotes a liquid chamber cover member that serves as a lid of the ink liquid chamber (pressurized liquid chamber) 107 formed on the ink liquid chamber substrate 108 and the common liquid chamber 111. The liquid chamber cover member 112 is provided with an ink supply port 113 for the common liquid chamber 111 and an ink nozzle 114 for ejecting (discharging) ink from the ink liquid chamber (pressurized liquid chamber) 107. This liquid chamber cover member 11
Metals such as stainless steel and nickel or resins such as polyimide can be used as the second material.

Further, in FIG.
Reference numeral 9 or 109 ′ indicates an ink droplet ejection (discharge) direction determined by the arrangement direction of the ink nozzle 114.
When the ink nozzle 114 is arranged in the normal direction of the electrode substrate 101, the ink droplet is ejected (discharged) in the direction of 109.
When the ink nozzle 114 is arranged on the cross section of the electrode substrate 101, the ink droplet is ejected (discharged) in the direction of 109 '.
I do. FIG. 3A illustrates an example in which the ink nozzles 114 are arranged on the surface of the ink liquid chamber substrate 108.

Next, an example of the arrangement of head chips and ink nozzles of a line type ink jet head according to an embodiment of the present invention will be described with reference to FIGS.
The head chip is formed by a piezoelectric element or another electromechanical transducer such as a piezoelectric element, which pressurizes the ink through a diaphragm constituting the wall of the ink liquid chamber (pressurized liquid chamber) 107, or a bubble generated by a heating resistor. A bubble type that generates and pressurizes ink, or an electrostatic type as described with reference to FIG. 3, that is, a diaphragm 110 that forms a wall surface of an ink liquid chamber (pressurized liquid chamber) 107 and an individual electrode that faces the diaphragm 110 An electrostatic type in which the diaphragm 110 is displaced by an electrostatic force between the pressure and the pressure of the ink to press the ink can be used.

As shown in FIG. 4, a plurality of ink nozzles are arranged in a straight line at a predetermined pitch on each head chip, and these ink nozzles are arranged at the same pitch in the line arrangement direction of the ink jet head. Then, the head chips were arranged in a line along the line arrangement direction in a state where the arrangement direction of the ink nozzles of each head chip was inclined at a constant angle θ with respect to the line arrangement direction.

The shape of the head chip was a rectangle in which the side length along the ink nozzle array direction was X (parallel to the ink nozzle row) and the side length orthogonal to it was Y. The arrangement position of the ink nozzles with respect to the head chip was set at the center of the side length Y. Assuming that the number of arranged ink nozzles is N, the arrangement pitch is P, the distance between the first ink nozzle and the short side of the head chip is M, and the distance between the Nth ink nozzle and the short side of the head chip is L, The side length X of the head chip along the nozzle arrangement direction is X = p × (n−1) + 1 + m.

Each head chip is arranged in an inclined state along a line arrangement direction orthogonal to the feeding direction of the recording medium (recording paper). The printing pitch of each ink nozzle on the recording medium (recording paper) is as follows. pcos θ, which is smaller than the pitch P on the head chip.

The head chips were arranged at equal intervals in the line arrangement direction with a mutual interval D. The mutual interval D between the head chips is set so that the printing pitch of pcosθ is maintained even between the ink nozzles of the adjacent head chips. That is, d = n · p · sin θ cos θ−Y is set.

When 1 = m = 0.5 mm, Y = 4 mm, and Pcos θ = 42.3 μm (600 dpi), θ = 6
At 0 ° and n = 211, p = 84.7 μm (corresponding to 300 dpi), X = 18.78 mm, d = 3,736 μm, and if the width of the recording medium (recording paper) is 297 mm, 33 head chips are arranged. . Θ = 70.5 °, n =
141, p = 127 μm (corresponding to 200 dpi), X = 1
If the width of the recording medium (recording paper) is 297 mm, 49 head chips are lined up with 8.78 mm, d = 1,627 μm.

As shown in FIG. 5, a plurality of ink nozzles are arranged on each head chip in parallel at a predetermined pitch in n rows, and these ink nozzles are arranged at the same pitch in the line arrangement direction of the ink jet head. In this manner, the head chips were arranged in a line along the line arrangement direction in a state where the arrangement direction of the ink nozzles of each head chip was inclined at an angle of θ with respect to the line arrangement direction.

The shape of the head chip was a parallelogram in which the side length along the arrangement direction of the ink nozzles was X (parallel to the ink nozzle row) and the side length orthogonal to it was Y. The number of arranged ink nozzles is n, the arrangement pitch is p, the distance between the first ink nozzle and the short side of the head chip is m, the distance between the nth ink nozzle and the short side of the head chip is l, and When the distance between the ink nozzle rows is r, the distance between the first ink nozzle row and the long side of the head chip is q, and the distance between the nth ink nozzle row and the long side of the head chip is s,
Side length X of head chip along ink nozzle array direction
X = p × (n−1) + (l + m) / sin θ + y / tan θ
Becomes Further, the side length Y of the head chip orthogonal to the arrangement direction of the ink nozzles is Y = q + (n-1) r + s.

Each head chip is arranged in an inclined state along a line arrangement direction orthogonal to the recording medium (recording paper) feed direction. The printing pitch of each ink nozzle on the recording medium (recording paper) is: pcos θ, which is smaller than the pitch p on the head chip.

The head chips were arranged at regular intervals in the line arrangement direction with a mutual interval d. The mutual distance d between the head chips is set so that the printing pitch of pcos θ is maintained even between the ink nozzles of the adjacent head chips. That is, d = n · p · cos θ− (q + s) / sin
is set to θ. The distance r between the ink nozzle rows is
Is represented by r = n · p · sin θ cos θ.

L = m = 05 mm, q = s = 2 mm, θ =
70.5 °, n = 116, and cos θ = 42.3 μ
In the case of m (600 dpi), when n = 2, p = 126.8 μm
m (equivalent to 200 dpi), X = 18.70 mm, r = 4.6
When 28 μm, Y = 8.63 mm, d = 4,902 μm, and the width of the recording medium (recording paper) is 297 mm, 60 head chips are arranged. When n = 3, p = 12
6.8 μm (corresponding to 200 dpi), X = 18.70 mm, r
= 4,628 μm, Y = 93.8 mm, d = 4,902
μm, and if the width of the recording medium (recording paper) is 297 mm, 40 head chips are arranged.

As shown in FIG. 6, a plurality of ink nozzles are arranged in each head chip in parallel with two rows at a predetermined pitch, and these ink nozzles are arranged at the same pitch in the line arrangement direction of the ink jet head. The head chips were arranged in a line along the line arrangement direction in a state where the arrangement direction of the ink nozzles of each head chip was inclined at an angle of θ to the line arrangement direction.

The shape of the head chip was a rectangle in which the side length along the ink nozzle array direction was X (parallel to the ink nozzle row) and the side length orthogonal to it was Y. The number of arranged ink nozzles is n, the arrangement pitch is p, the distance between the first ink nozzle and the short side of the head chip is m, the distance between the nth ink nozzle and the short side of the head chip is l, If the distance between the ink nozzle rows is r, the distance between the first ink nozzle row and the long side of the head chip is q, the distance between the second ink nozzle row and the long side of the head chip is s, The side length X of the head chip along the arrangement direction of the ink nozzles is X
= P × (n−1) + 1 + m. The side length Y of the head chip orthogonal to the ink nozzle arrangement direction is Y = q +
r + s.

Each head chip is arranged in an inclined state along a line arrangement direction orthogonal to the feed direction of the recording medium (recording paper). The printing pitch of each ink nozzle on the recording medium (recording paper) is as follows. cos θ, which is smaller than the pitch p on the head chip.

The head chips were arranged at regular intervals in the line arrangement direction with a mutual interval d. The interval d between the head chips is set so that the printing pitch of p · cos θ is maintained even between the ink nozzles of the adjacent head chips. That is, d = n · p · sin θ cos θ−Y is set. The distance r between the ink nozzle rows is r = p
・ It is expressed by arctanθ.

When l = m = 0.5 mm, q = s = 2 mm, and pcos θ = 42.3 μm (600 dpi), θ =
At 60 ° and n = 211, p = 84.7 μm (300 dpi)
X = 18.78 mm, r = 48.9 μm, Y =
If 4 mm, d = 3,687 μm and the width of the recording medium (recording paper) is 297 mm, 33 head chips are arranged. When θ = 70.5 ° and n = 141, p = 1
27 μm (corresponding to 200 dpi), X = 18.76 mm, r =
Assuming that 44.9 μm, Y = 4 mm, d = 1,582 μm, and the width of the recording medium (recording paper) is 297 mm, 49 head chips are arranged.

As shown in FIG. 7, a plurality of ink nozzles are arranged in a straight line at a predetermined pitch in each head chip, and these ink nozzles are arranged at the same pitch in the line arrangement direction of the ink jet head. Then, the head chips were arranged in two rows in a staggered manner along the line arrangement direction in a state where the arrangement direction of the ink nozzles of each head chip was at an angle of θ with respect to the line arrangement direction.

The shape of the head chip was a rectangle in which the side length along the arrangement direction of the ink nozzles was X (parallel to the ink nozzle row) and the side length orthogonal to it was Y. The arrangement position of the ink nozzles with respect to the head chip was set at the center of the side length Y. Assuming that the number of arranged ink nozzles is n, the arrangement pitch is p, the distance between the first ink nozzle and the short side of the head chip is m, and the distance between the nth ink nozzle and the short side of the head chip is 1, The side length X of the head chip along the nozzle arrangement direction is X = p × (n−1) + 1 + m.

Each head chip is arranged in an inclined state along a line arrangement direction orthogonal to the feeding direction of the recording medium (recording paper). The printing pitch of each ink nozzle on the recording medium (recording paper) is as follows. pcos θ, which is smaller than the pitch p on the head chip.

The first row and the second row of the head chips arranged in a zigzag pattern in two rows were arranged at equal intervals in the line arrangement direction with a mutual interval D. The head chips in the first row and the second row, which are adjacent and alternately arranged side by side, are arranged with a mutual positional shift W in a line arrangement direction orthogonal to the feeding direction of the recording medium (recording paper). The mutual spacing D and the mutual positional deviation w of the head chips are set so as to maintain the print pitch of pcos θ even between the ink nozzles of the adjacent head chips arranged in a staggered manner. That is, the mutual interval d is set to d = 2n · p · sin θ cos θ−Y,
The mutual position shift w is set to w = n · p · cos θ.
The distance between the first and second rows of each head chip can be arbitrarily selected. However, if the distance between the rows is increased, the size of the head is increased. Preferably not.

When l = m = 0.5 mm, Y = 3 mm and pcos θ = 42.3 μm (600 dpi), θ = 7
At 5.5 ° and n = 109, p = 169 μm (150 dpi
Equivalent), X = 18.65 mm, d = 5,934 μm, and if the width of the recording medium (recording paper) is 297 mm, the head chips are arranged in two rows of 32 per row. Also, θ
= 60 ° and n = 218, p = 84.7 μm (300 d
pi), X = 18.77 mm, d = 12,985 μm
Assuming that the width of the recording medium (recording paper) is 297 mm, the head chips are arranged in two rows of 16 chips per row.

As shown in FIG. 8, a plurality of ink nozzles are arranged in each head chip in parallel with two rows at a predetermined pitch, and the ink nozzles are arranged at the same pitch in the line arrangement direction of the ink jet head. The head chips were arranged in two rows in a staggered manner along the line arrangement direction in a state where the arrangement direction of the ink nozzles of each head chip was inclined at an angle of θ with respect to the line arrangement direction.

The shape of the head chip was rectangular, with the side length along the ink nozzle array direction being X (parallel to the ink nozzle row) and the side length orthogonal to it being Y. The number of arranged ink nozzles is n, the arrangement pitch is p, the distance between the first ink nozzle and the short side of the head chip is m, the distance between the nth ink nozzle and the short side of the head chip is l, If the distance between the ink nozzle rows is r, the distance between the first ink nozzle row and the long side of the head chip is q, the distance between the second ink nozzle row and the long side of the head chip is s, The side length X of the head chip along the arrangement direction of the ink nozzles is X
= P × (n−1) + 1 + m. The side length Y of the head chip orthogonal to the ink nozzle arrangement direction is Y = q +
r + s.

Each head chip is arranged in an inclined state along a line arrangement direction orthogonal to the feed direction of the recording medium (recording paper). The printing pitch of each ink nozzle on the recording medium (recording paper) is as follows. pcos θ, which is smaller than the pitch p on the head chip.

The first row and the second row of the head chips arranged in a staggered manner in two rows were arranged at equal intervals in the line arrangement direction with a mutual interval d. The head chips in the first row and the second row, which are adjacent and alternately arranged side by side, are arranged with a mutual positional deviation w in a line arrangement direction orthogonal to the feeding direction of the recording medium (recording paper). The mutual spacing d and mutual positional deviation w of the head chips are set so that the printing pitch of pcos θ is maintained even between the ink nozzles of the adjacent head chips arranged in a staggered manner. That is, the mutual interval d is set to d = 2n · p · sin θ cos θ−Y,
The mutual position shift w is set to w = n · p · cos θ.
The distance r between the ink nozzle rows is r = p · arctan
It is represented by θ. The distance between the first and second rows of each head chip can be arbitrarily selected. However, if the distance between the rows is increased, the size of the head is increased. Preferably not.

1 = m = 0.5 mm, q = s = 1.5 mm
And when pcosθ = 42.3 μm (600 dpi),
When θ = 60 ° and n = 211, p = 84.7 μm (30
0 = dpi), r = 48.9 μm, X = 18.78 m
If m, Y = 3 mm, d = 12,422 μm, and the width of the recording medium (recording paper) is 297 mm, 16 head chips are arranged in one row and 15 head chips are arranged in another row.

[0056]

As described above, in the line type ink jet head according to the present invention, since the ink nozzle arrangement direction of each head chip is at an angle θ with respect to the line arrangement direction, a predetermined angle is assigned to each head chip. The plurality of ink nozzles arranged in a straight line at a pitch are arranged in the line arrangement direction at the same pitch smaller than the predetermined pitch. In other words, the arrangement pitch of the plurality of ink nozzles on each head chip can be wider than the required dot formation pitch on the recording medium (recording paper). Therefore, according to the present invention, it is possible to reduce mutual interference between adjacent ink nozzles and between ink pressurizing means (actuators), and to reduce variations in the positional shift of each ink nozzle. As a result, variations in printing characteristics can be reduced and printing quality can be improved.

Further, in the line type ink jet head of the present invention, since a plurality of ink jet heads are arranged in a line, the production yield is improved as compared with the line method using a single ink jet head.

In the line type ink jet head of the present invention, when the head chips are arranged in two rows in a staggered manner on the same substrate, the space between the adjacent ink jet heads is widened to sufficiently mount the mounting area of each ink jet head. Can be taken.

Further, in the line type ink jet head of the present invention, when an electrostatic pressurizing means is provided as the pressurizing means, power consumption can be reduced.

On the other hand, since the ink jet recording apparatus according to the present invention is provided with the line type ink jet head of the present invention, it is possible to reduce variations in printing characteristics and improve printing quality.

[Brief description of the drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the ink jet recording apparatus shown in FIG.

3A and 3B schematically show the structure of a line-type inkjet head according to an embodiment of the present invention, wherein FIG. 3A is a plan view thereof, FIG. 3B is a sectional view taken along line BB of FIG. Is (a)
It is CC sectional view taken on the line of FIG.

FIG. 4 is an arrangement diagram of a head chip and ink nozzles.

FIG. 5 is a second arrangement diagram of head chips and ink nozzles.

FIG. 6 is a third arrangement diagram of head chips and ink nozzles.

FIG. 7 is a fourth arrangement diagram of head chips and ink nozzles.

FIG. 8 is a fifth arrangement diagram of head chips and ink nozzles.

[Explanation of symbols]

14: inkjet head, 101: electrode substrate, 10
2: individual electrode 107: ink liquid chamber (pressurized liquid chamber), 110: diaphragm, 1
14: Ink nozzle.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Goichi Otaka 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C057 AF37 AF40 AF54 AF93 AG14 AG15 AG16 AG55 AG85 AN05 AP02 AP52 AP53 AP56 AP71 AQ02 AQ03 AQ06 BA03 BA15

Claims (9)

[Claims] 1. A plurality of ink jet heads configured to individually pressurize ink in a plurality of ink liquid chambers by a pressurizing means to individually jet ink droplets from a plurality of ink nozzles are arranged in a line. In the line type ink jet head, the plurality of ink nozzles are linearly arranged at a predetermined pitch on a head chip of each ink jet head, and these ink nozzles are arranged at the same pitch in the line arrangement direction of the ink jet head. A line type ink jet head wherein each head chip is arranged on the same substrate in such a state that the ink nozzle arrangement direction of each head chip is at a constant angle with respect to the line arrangement direction. 2. The line type ink jet head according to claim 1, wherein the plurality of ink nozzles are arranged in a line on each of the head chips, and the head chips are arranged in a line on the same substrate. A line-type inkjet head characterized in that: 3. The line-type ink jet head according to claim 1, wherein the plurality of ink nozzles are arranged in one line on each of the head chips, and the head chips are arranged in two lines on the same substrate in a staggered manner. A line-type inkjet head characterized by being arranged in a line. 4. The line type ink jet head according to claim 1, wherein the plurality of ink nozzles are arranged in a plurality of rows in parallel with each of the head chips, and the head chips are arranged in a single row on the same substrate. A line-type inkjet head characterized by being arranged. 5. The line-type inkjet head according to claim 1, wherein the plurality of ink nozzles are arranged in a plurality of rows in parallel with each of the head chips, and each of the head chips is staggered in two rows on the same substrate. A line type inkjet head characterized by being arranged in a shape. 6. The line type ink jet head according to claim 1, wherein the plurality of ink nozzles are arranged in two rows in parallel with each of the head chips, and the head chips are arranged in one row on the same substrate. A line-type inkjet head characterized by being arranged. 7. The line type ink jet head according to claim 1, wherein the plurality of ink nozzles are arranged in two rows in parallel with each of the head chips, and the head chips are staggered in two rows on the same substrate. A line type inkjet head characterized by being arranged in a shape. 8. The line type ink jet head according to claim 1, wherein the pressure means includes a diaphragm constituting a wall surface of the ink liquid chamber, and an electrode facing the diaphragm. A line type ink jet head comprising electrostatic pressing means for pressing the ink in the ink liquid chamber by displacing the vibration plate by electrostatic force during the period. 9. An ink jet recording apparatus comprising the line type ink jet head according to claim 1. Description: