JP6540302B2 - Ink jet recording apparatus and ink jet recording method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly, to an ink jet in which the amount of droplets can be easily adjusted without changing the droplet velocity of ink ejected from a nozzle among a plurality of inkjet heads. The present invention relates to a recording apparatus and an inkjet recording method.

  In recent years, also in image formation using an inkjet head, high-definition image quality comparable to photographic images is required. For this reason, the amount of ink droplets ejected from the nozzles of the inkjet head is strictly controlled.

  Conventionally, Patent Document 1 discloses a first waveform element that expands the volume of the pressure chamber in view of the change in ink viscosity and the change in ink droplet velocity and ink droplet volume due to environmental temperature change; The first waveform element and the second waveform element in the drive signal including a second waveform element that holds the expanded state and a third waveform element that shrinks the volume of the pressure chamber to eject the ink droplet. It is described that the difference between the potential difference and the potential difference between the third waveform element and the second waveform element is reduced when the environmental temperature is high and increased when the environmental temperature is low.

  Patent Document 2 describes that when the temperature rises and the viscosity of the ink decreases, the amplitude of the drive signal is changed to decrease according to a predetermined equation.

  In Patent Document 3, a plurality of nozzles of an ink jet head is divided into a plurality of groups of one or more nozzles, a drive voltage value of expansion pulse is set commonly for each group, and a drive voltage value of contraction pulse is group by group It is described that the fluctuation of the droplet amount due to the variation of the droplet velocity for each nozzle is suppressed to a small value by applying to the head the drive signal which is set independently according to the magnitude of the droplet velocity.

Unexamined-Japanese-Patent No. 2004-42576 Unexamined-Japanese-Patent No. 2005-212365 Re-publication 2012-121019 gazette

  When forming an image on a recording medium using a plurality of inkjet heads, if the amount of droplets of ink ejected from each inkjet head is not appropriate or if the amount of droplet varies among the inkjet heads And may reduce the image quality.

  Also, in general, the amount of ink droplets ejected can be changed by adjusting the voltage value of the drive signal. Therefore, by adjusting the voltage value of the drive signal applied to the ink jet head having a nonuniform droplet amount, it is possible to make the amount of droplet uniform among the plurality of ink jet heads. However, simply adjusting the voltage value of the drive signal may change the droplet velocity accordingly, which may cause landing position deviation. In this case, at the same time as the adjustment of the droplet amount, an operation to adjust the discharge timing anew is required. For this reason, it is desirable that the amount of droplets of each of the plurality of inkjet heads can be easily adjusted without changing the droplet velocity.

  The Patent Documents 1 and 2 change the drive signal in accordance with the viscosity change of the ink, and the Patent Document 3 suppresses the fluctuation of the droplet amount among the plurality of nozzles of the ink jet head. . Therefore, none of them adjust the droplet volume of each of the plurality of inkjet heads without changing the droplet velocity.

  Therefore, the present invention provides an inkjet recording apparatus and an inkjet recording method in which the droplet amount can be easily adjusted without changing the droplet velocity of the ink ejected from the nozzles among a plurality of inkjet heads. To be an issue.

  Other objects of the present invention will become apparent from the following description.

1.
A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio .DELTA.V2 / .DELTA.V1 is configured to be independently adjustable in each of the plurality of ink jet heads, and the potential difference ratio .DELTA.V2 / .DELTA.V1 is independently adjusted in each of the plurality of ink jet heads. An ink jet recording apparatus , wherein the amount of ink droplets ejected is made uniform by the plurality of ink jet heads .
2.
The drive circuit is configured to equalize the droplet velocity of the ink ejected from the nozzle by each of the plurality of inkjet heads by adjusting the potential difference ΔV1 independently for each of the plurality of inkjet heads. The ink jet recording apparatus according to the above-mentioned 1, characterized in that
3.
A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio .DELTA.V2 / .DELTA.V1 is configured to be adjustable independently for each of the plurality of inkjet heads, and is discharged from the nozzle by adjusting the potential difference .DELTA.V1 independently for each of the plurality of inkjet heads. An ink jet recording apparatus , wherein the droplet velocity of ink is made uniform by the plurality of ink jet heads .
4.
A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio ΔV2 / ΔV1 is configured to be independently adjustable in each of the plurality of inkjet heads,
The plurality of inkjet heads include inkjet heads having different physical properties of ink,
The drive circuit makes the droplet amount of the ink ejected from the nozzle uniform by adjusting the potential difference ratio ΔV2 / ΔV1 independently for each of the plurality of ink jet heads with the plurality of ink jet heads. an ink jet recording apparatus characterized by there.
5.
The physical property of the ink is the viscosity of the ink,
5. The inkjet recording apparatus according to 4, wherein the potential difference ratio ΔV2 / ΔV1 is increased as the viscosity of the ink is higher among the plurality of inkjet heads, in the drive circuit.
6.
Among the plurality of ink jet heads, the drive circuit increases the potential difference ΔV1 as the viscosity of the ink is higher, so that the droplet velocity of the ink ejected from the nozzle is equal to that of the plurality of ink jet heads. 5. The ink jet recording apparatus as described in 5 above, which is uniform.
7.
The driving circuit is configured to be able to adjust the potential difference ratio ΔV2 / ΔV1 independently in each of the plurality of inkjet heads within a range of 0.8 or more and 1.2 or less. The inkjet recording device according to any one of to 6.
8.
A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio .DELTA.V2 / .DELTA.V1 is configured to be adjustable independently for each of the plurality of inkjet heads, and the potential difference ratio .DELTA.V2 / .DELTA.V1 is in the range of 0.8 or more and 1.2 or less, the plurality of inkjet heads An ink jet printing apparatus, wherein each of the ink jet recording apparatuses is independently adjustable .
9.
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The inkjet recording apparatus according to any one of 1 to 8 , wherein / T1 is 0.6 or more and 1.2 or less.
10.
A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio ΔV2 / ΔV1 is configured to be independently adjustable in each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 An inkjet recording apparatus characterized in that / T1 is 0.6 or more and 1.2 or less .
11.
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording apparatus according to any one of 1 to 8 , wherein / T1 is 0.6 or more and 1.0 or less.
12.
A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio ΔV2 / ΔV1 is configured to be independently adjustable in each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 An inkjet recording apparatus characterized in that / T1 is 0.6 or more and 1.0 or less .
13.
When the vibration period of the ink in the pressure chamber is Tc, a period T1 from the start end of the first expansion pulse to the start end of the first contraction pulse is not less than 0.45 Tc and not more than 0.55 Tc. The inkjet recording apparatus according to any one of the above 1 to 12 , wherein
14.
The ink jet recording apparatus according to any one of 1 to 13 , wherein .DELTA.V2> .DELTA.V3 where .DELTA.V3 is the potential difference between the start point of the second contraction pulse and the reference potential.
15.
The ink jet recording apparatus as described in 14 above, wherein the potential difference ratio ΔV 3 / ΔV 2 is 0.3 or more and 0.9 or less.
16.
The ink jet recording apparatus as described in 14 above, wherein the potential difference ratio ΔV 3 / ΔV 2 is 0.5 or more and 0.9 or less.
17.
The inkjet recording apparatus according to any one of the above 1 to 16 , wherein the drive signal is a slope waveform.
18.
By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads ,
By adjusting the potential difference ratio ΔV 2 / ΔV 1 independently in each of the plurality of inkjet heads, the droplet amount of the ink ejected from the nozzle is equalized by the plurality of inkjet heads. Ink jet recording method.
19.
In each of the plurality of inkjet heads, by adjusting the potential difference ΔV1 independently, the 18, wherein the droplet velocity of the ink ejected from the nozzle and homogenized with the plurality of inkjet heads Inkjet recording method.
20.
By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
An ink jet recording method characterized in that the droplet velocity of the ink ejected from the nozzle is made uniform by the plurality of ink jet heads by independently adjusting the potential difference ΔV1 in each of the plurality of ink jet heads. .
21.
By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
The plurality of inkjet heads include inkjet heads having different physical properties of ink,
By adjusting the potential difference ratio ΔV 2 / ΔV 1 independently in each of the plurality of inkjet heads, the droplet amount of the ink ejected from the nozzle is equalized by the plurality of inkjet heads. Ink jet recording method.
22.
The physical property of the ink is the viscosity of the ink,
21. The ink jet recording method according to 21 above, wherein among the plurality of ink jet heads, the higher the viscosity of the ink, the larger the potential difference ratio ΔV2 / ΔV1.
23.
Among the plurality of inkjet heads, by increasing the potential difference ΔV1 as the viscosity of the ink is higher, the droplet velocity of the ink ejected from the nozzle is made uniform by the plurality of inkjet heads. 23. The ink jet recording method as described in 22 above characterized.
24.
The inkjet recording according to any one of 18 to 23 , wherein the potential difference ratio ΔV2 / ΔV1 is adjusted independently for each of the plurality of inkjet heads within the range of 0.8 or more and 1.2 or less. Method.
25.
By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
An ink jet recording method, wherein the potential difference ratio ΔV2 / ΔV1 is adjusted independently for each of the plurality of ink jet heads within a range of 0.8 or more and 1.2 or less .
26.
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording method according to any one of 18 to 25, wherein / T1 is 0.6 or more and 1.2 or less.
27.
By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 And / T1 is 0.6 or more and 1.2 or less .
28.
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording method according to any one of 18 to 25, wherein / T1 is 0.6 or more and 1.0 or less.
29.
By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 And / T1 is 0.6 or more and 1.0 or less .
30.
When the vibration period of the ink in the pressure chamber is Tc, a period T1 from the start end of the first expansion pulse to the start end of the first contraction pulse is not less than 0.45 Tc and not more than 0.55 Tc. The inkjet recording method according to any one of 18 to 29 above.
31.
The ink jet recording method according to any one of 18 to 30 , wherein .DELTA.V2> .DELTA.V3 where .DELTA.V3 is the potential difference between the start point of the second contraction pulse and the reference potential.
32.
The ink jet recording method according to the above 31, wherein the potential difference ratio ΔV3 / ΔV2 is 0.3 or more and 0.9 or less.
33.
31. The ink jet recording method according to 31, wherein the potential difference ratio ΔV 3 / ΔV 2 is 0.5 or more and 0.9 or less.
34.
The inkjet recording method according to any one of 18 to 33 , wherein the drive signal is a slope waveform.

  According to the present invention, an ink jet recording apparatus and an ink jet recording method are provided in which the amount of droplets can be easily adjusted without changing the droplet velocity of ink ejected from the nozzles among a plurality of ink jet heads. be able to.

The schematic block diagram which shows one Embodiment of the inkjet recording device based on this invention Cross-sectional view showing an embodiment of an inkjet head Block diagram showing an embodiment of the electrical configuration of the inkjet recording apparatus Figure showing an embodiment of the drive signal An explanatory view of a drive signal in which the potential difference ratio ΔV2 / ΔV1 is adjusted (A) An explanatory view of a large droplet being discharged by the drive signal in which the potential difference ratio ΔV2 / ΔV1 is largely changed, and (b) an illustration of the middle droplet being discharged by the drive signal in which the potential difference ratio ΔV2 / ΔV1 is not changed (C) Explanatory drawing of a mode which discharges a small droplet by the drive signal by which potential difference ratio (DELTA) V2 / (DELTA) V1 was changed small Graph showing the relationship between the potential difference ratio ΔV2 / ΔV1 and the droplet amount ratio Graph showing the relationship between the potential difference ratio ΔV2 / ΔV1 and the droplet velocity

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration view showing an embodiment of an ink jet recording apparatus according to the present invention.

  The inkjet recording apparatus 1 includes a plurality of inkjet heads 10A to 10D. In the present embodiment, for example, four inkjet heads 10A to 10D for each ink color of Y (yellow), M (magenta), C (cyan), and K (black) are in the illustrated XX 'direction (main scanning direction). In the present invention, the number of ink jet heads is not limited in particular, as long as it is plural.

  Each of the inkjet heads 10A to 10D is mounted on a common carriage 20 so that the nozzle surface side faces the recording medium 50, and a control device (not shown in FIG. 1) provided on the inkjet recording apparatus 1 via a flexible cable 30. Electrically connected).

  The carriage 20 is reciprocally movable in the main scanning direction along the guide rail 40 by a main scanning motor (not shown in FIG. 1). Further, the recording medium 50 is intermittently conveyed by a predetermined amount along a Y direction shown in the drawing, which intersects the main scanning direction, by driving of a sub scanning motor (not shown in FIG. 1).

  The inkjet recording apparatus 1 ejects ink from the nozzles of the inkjet heads 10A to 10D toward the recording medium 50 in the process of moving the inkjet heads 10A to 10D in the main scanning direction by the movement of the carriage 20. Then, a predetermined image is printed on the recording medium 50 by the cooperation of the movement of the inkjet heads 10A to 10D in the main scanning direction and the intermittent conveyance of the recording medium 50 in the subscanning direction.

  Next, one embodiment of the inkjet heads 10A to 10D will be described using a cross-sectional view of the inkjet head shown in FIG. Since each inkjet head 10A-10D is the same structure, in FIG. 2, the structure of one inkjet head shown with the code | symbol 10 is demonstrated.

  The inkjet head 10 is configured by laminating the head substrate 11, the wiring substrate 12, and the adhesive resin layer 13. An ink manifold 14 is bonded to the upper surface of the wiring substrate 12. The inside of the ink manifold 14 is a common ink chamber 14 a in which the ink is stored with the wiring substrate 12.

The head substrate 11 includes a nozzle plate 11a formed of a Si (silicon) substrate, an intermediate plate 11b formed of a glass substrate, a pressure chamber plate 11c formed of a Si (silicon) substrate, and SiO ₂ from the lower side in the drawing. A diaphragm 11d formed of a thin film is stacked. A plurality of nozzles 11e are opened at the lower surface of the nozzle plate 11a.

  The pressure chamber plate 11c is formed with a plurality of pressure chambers 15 in which ink is stored. The upper wall of the pressure chamber 15 is constituted by the diaphragm 11d, and the lower wall is constituted by the intermediate plate 11b. Each pressure chamber 15 is in communication with the nozzle 11 e via the intermediate plate 11 b.

  The actuators 16 are stacked on the upper surface of the diaphragm 11 d in one-to-one correspondence with the pressure chambers 15. The actuator 16 has a structure in which a piezoelectric element such as a thin film PZT is sandwiched between an upper electrode as a drive electrode and a lower electrode (both not shown). The upper electrode is disposed on the upper surface of the actuator body, and the lower electrode is disposed on the lower surface of the piezoelectric element. The lower electrode extends on the upper surface of the diaphragm 11 d and constitutes a common electrode common to all the actuators 16. The lower electrode is grounded.

  Wiring substrate 12 is provided with a wiring for applying a drive signal from a drive circuit (not shown in FIGS. 1 and 2) provided for each of inkjet heads 10A to 10D to drive electrodes of each actuator 16. It is.

  The adhesive resin layer 13 is formed of, for example, a thermosetting photosensitive adhesive resin sheet, and integrally bonds the two substrates 11 and 12 between the head substrate 11 and the wiring substrate 12. A space corresponding to the thickness of the adhesive resin layer 13 is provided between the two substrates 11 and 12. The adhesive resin layer 13 has the area corresponding to the actuator 16 and the periphery thereof removed by exposure and development. Each actuator 16 is disposed in the space where the adhesive resin layer 13 is removed.

  In the adhesive resin layer 13, through holes 13 a penetrating vertically are formed corresponding to the respective pressure chambers 15. One end (upper end) of each through hole 13 a communicates with the ink supply path 12 a formed in the wiring substrate 12, and the other end (lower end) communicates with the inside of the pressure chamber 15. The ink supply path 12a is open to the common ink chamber 14a.

  In the ink jet head 10, ink is supplied from the common ink chamber 14a into the pressure chambers 15 through the ink supply path 12a and the through holes 13a. Then, when a drive signal including an expansion pulse and a contraction pulse is applied from the drive circuit to the drive electrode of each actuator 16 as described later, the actuator 16 deforms and the diaphragm 11d vibrates, and the corresponding pressure The volume of the chamber 15 expands and contracts. As a result, a pressure change is applied to the ink in the pressure chamber 15, and the ink is ejected from the nozzle 11e toward the recording medium 50.

  FIG. 3 is a block diagram showing an embodiment of the electrical configuration of the inkjet recording apparatus 1.

  In FIG. 3, 100 is a control device, 200 is a host computer, and 60A to 60D are driving circuits corresponding to the ink jet heads 10A to 10D one to one.

  The control device 100 includes an interface controller 101, an image memory 102, a transfer unit 103, a CPU 104, a main scanning motor 105, a sub scanning motor 106, an input operation unit 107, a drive signal generation circuit 108 and the like.

  The interface controller 101 captures image information to be printed on the recording medium 50 from a host computer 200 connected via a communication line.

  The image memory 102 temporarily stores image information acquired via the interface controller 101. The image information of the image memory 102 is sent to the drive circuits 60A to 60D.

  The transfer means 103 transfers partial image information recorded by one discharge from a plurality of nozzles of each of the ink jet heads 10A to 10D from the image memory 102 to each of the drive circuits 60A to 60D. The transfer means 103 includes a timing generation circuit 103a and a memory control circuit 103b. The timing generation circuit 103a obtains positional information of the carriage 20 by, for example, an encoder sensor (not shown). The memory control circuit 103b obtains an address of partial image information required for each of the ink jet heads 10A to 10D from the position information. Then, using the address of this partial image information, the memory control circuit 103b performs reading from the image memory 102 and transfer to the drive circuits 60A to 60D.

  The CPU 104 is a control unit that controls the inkjet recording apparatus 1, and controls conveyance of the recording medium 50, movement of the carriage 20, and ejection of ink from the inkjet heads 10A to 10D.

  The main scanning motor 105 is a motor for moving the carriage 20 shown in FIG. 1 in the main scanning direction. The sub scanning motor 106 is a motor for transporting the recording medium 50 in the sub scanning direction. The driving of the motors 105 and 106 is controlled by the CPU 104.

  The input operation unit 107 is a portion where the CPU 104 receives various input operations by the operator, and is configured of, for example, a touch panel.

  The drive signal generation circuit 108 generates a signal waveform of a drive signal for causing the ink jet heads 10A to 10D to eject ink. The signal waveform is generated for each latch signal in synchronization with the latch signal of the image information of the timing generation circuit 103a, and is output to the drive circuits 60A to 60D.

  The drive circuits 60A to 60D drive the respective actuators 16 of the corresponding inkjet heads 10A to 10D. The drive circuits 60A to 60D are mounted on the carriage 20 together with the inkjet heads 10A to 10D, and are electrically connected to the control device 100 by a flexible cable 30.

  The drive circuits 60A to 60D include voltage setting units 61A to 61D, respectively. The voltage setting units 61A to 61D set a predetermined voltage for the signal waveform of the drive signal sent from the drive signal generation circuit 108. The drive circuits 60A to 60D apply the drive signals whose voltages are set by the voltage setting units 61A to 61D to the drive electrodes of the corresponding actuators 16 of the inkjet heads 10A to 10D based on the image information sent from the image memory 102. Do. The voltage values set by the voltage setting units 61A to 61D can be controlled independently by the CPU 104 for each of the drive circuits 60A to 60D.

  Next, the drive signal will be described.

  FIG. 4 shows an embodiment of drive signals output from the drive circuits 60A to 60D to the inkjet heads 10A to 10D.

  The drive signal P is a first expansion pulse P1 which expands the volume of the pressure chamber 15 starting from a reference potential, and a first contraction pulse P2 which contracts the volume of the pressure chamber 15 and discharges the ink from the nozzle. A second expansion pulse P3 for expanding the volume of the pressure chamber 15 and a second contraction pulse P4 for contracting the volume of the pressure chamber 15 and returning to the reference potential are included in this order.

  A sustain pulse P5 for maintaining the potential of the first expansion pulse P1 is provided between the end of the first expansion pulse P1 and the beginning of the first contraction pulse P2. Further, an intermediate pulse P6 for holding a constant potential is provided between the end of the first contraction pulse P2 and the beginning of the second expansion pulse P3. Further, between the end of the second expansion pulse P3 and the beginning of the second contraction pulse P4, there is a sustain pulse P7 for maintaining the potential of the second expansion pulse P3.

  Although the sustaining pulses P5 and P7 are flat pulses in this embodiment, the sustaining pulses P5 and P7 are not necessarily limited to flat pulses, and may be slightly inclined upward to such an extent that there is no problem with ink ejection.

  Also, ΔV1 is a potential difference between the reference potential and the end of the first expansion pulse P1. ΔV2 is a potential difference between the start and end of the first contraction pulse P2. ΔV3 is a potential difference between the start of the second contraction pulse P4 and the reference potential.

  The drive signal P shown in the present embodiment has a slope waveform in which rising and falling of each of the pulses P1, P2, P3 and P4 are inclined. The slope waveform has an effect of suppressing unstable discharge such as satellite, speed abnormality, and bending, and so this is a preferable embodiment in the present invention.

  When the drive signal P is applied to the drive electrodes of the actuators 16 of the inkjet heads 10A to 10D, first, the volume of the pressure chamber 15 expands from the initial state where neither expansion nor contraction is performed by the first expansion pulse P1. Begin to. Thus, the ink flows from the common ink chamber 14 a into the pressure chamber 15. This expanded state is maintained for the duration of the sustain pulse P5.

  Then, the first contraction pulse P2 causes the volume of the pressure chamber 15 in the expanded state to contract. The contraction of the volume of the pressure chamber 15 generates a positive pressure wave in the pressure chamber 15. Thus, the ink is pushed out of the nozzle 11 e and the ink is ejected. This contraction state is maintained for the duration of the intermediate pulse P6.

  Then, the volume of the pressure chamber 15 starts to expand again by the second expansion pulse P3. After the intermediate pulse P6, the pulse started by the second expansion pulse P3 is a cancellation pulse that cancels the reverberation pressure wave in the pressure chamber 15 generated by the first contraction pulse P2. The expansion of the volume of the pressure chamber 15 generates a negative pressure wave in the pressure chamber 15. As a result, the positive pressure wave generated in the pressure chamber 15 is canceled by the first contraction pulse P2.

  At the same time, the tail portion of the ink pushed out of the nozzle 11e by the first contraction pulse P3 is pulled toward the nozzle 11e. As a result, the ink ejected from the nozzle 11 e by the first contraction pulse P 2 is forcibly separated from the ink inside the nozzle 11 e. By pulling the tail portion of the ink, the tail portion is shortened, so that satellites accompanying the ejected ink are also suppressed. The separated ink lands on the recording medium 50 to form dots. The expansion state by the second expansion pulse P3 is maintained for the period of the maintenance pulse P7.

  Then, the volume of the pressure chamber 15 is contracted again by the second contraction pulse P4. Thereafter, as the second contraction pulse P4 returns to the reference potential, the volume of the pressure chamber 15 returns to the initial state in which neither expansion nor contraction is performed.

  Here, the drive circuits 60A to 60D are configured such that the potential difference ratio ΔV2 / ΔV1 between the potential differences ΔV1 and ΔV2 can be independently adjusted by each of the ink jet heads 10A to 10D by each of the voltage setting units 61A to 61D. . By adjusting the potential difference ratio ΔV2 / ΔV1 to a large or small size, the amount of droplets discharged from the nozzle 11e can be increased or decreased.

  FIG. 5 shows how the potential difference ratio ΔV2 / ΔV1 of the drive signal P is adjusted. FIG. 5 shows a state in which the potential difference ratio ΔV2 / ΔV1 is adjusted by changing the potential difference ΔV2 in magnitude while maintaining the potential difference ΔV1 in the drive signal P constant to increase or decrease the droplet amount. Further, in the present embodiment, the start potential of the first contraction pulse P2 and the end potential of the second expansion pulse P3 are maintained at a constant potential without changing from the viewpoint of suppression of satellites and stable ejection. It shows a preferred embodiment in the present invention.

  Drive circuits 60A to 60D adjust the potential difference ratio ΔV2 / ΔV1 of drive signal P in voltage setting units 61A to 61D, and drive signal Pa in which potential difference ΔV2 is increased as shown by the one-dot chain line in FIG. As indicated by a two-dot chain line in FIG. 5, the potential difference ΔV2 is made variable with the drive signal Pc reduced. At this time, the sustain period of the intermediate pulse P6 is not changed, and the slopes of the first contraction pulse P2 and the second expansion pulse P3 are changed. Thus, even if the potential difference ratio ΔV2 / ΔV1 is adjusted, the period from the start of the first expansion pulse P1 to the end of the second contraction pulse P4 remains unchanged, and the maximum drive frequency does not change. Preferred in the invention. However, when importance is placed on suppression of unstable discharge such as satellites, the inclinations of the first contraction pulse P2 and the second expansion pulse P3 may be made constant by changing the sustain period of the intermediate pulse P6. Good.

  As described above, by adjusting the potential difference ratio ΔV2 / ΔV1 of the drive signal P, the potential of the intermediate pulse P6 changes relatively. As a result, when the volume of the pressure chamber 15 is contracted by the first contraction pulse P2, the ejection amount of the ink pushed out from the nozzle 11e changes.

  For example, when the drive signal Pa is applied to the drive electrode of the actuator 16, the potential of the intermediate pulse P6 becomes relatively larger than when the drive signal Pb which is the reference potential is applied. The amount of contraction of the pressure chamber 15 also increases. As a result, as shown in FIG. 6A, the pushing amount L1 of the ink 300 pushed out from the nozzle 11e is greater than the pushing amount L2 of the ink 300 when the drive signal Pb shown in FIG. 6B is applied. growing. Then, the ink 300 is forcibly separated by the cancel pulse in a state where the amount of extrusion is large. For this reason, from the nozzle 11e, the droplet 301 having a droplet amount larger than the droplet 302 shown in FIG. 6B which is ejected by the drive signal Pb is ejected.

  On the other hand, when the drive signal Pc is applied to the drive electrode of the actuator 16, the potential of the intermediate pulse P6 is relatively lowered, and the amount of contraction of the volume of the pressure chamber 15 by the first contraction pulse P2 also decreases. As a result, as shown in FIG. 6C, the amount L3 of ejection of the ink 300 ejected from the nozzle 11e is greater than the amount L2 of ejection of the ink 300 when the drive signal Pb shown in FIG. 6B is applied. It becomes smaller. Then, by the cancel pulse, the ink 300 is forcibly separated in a state where the amount of extrusion is small. For this reason, the droplet 303 having a droplet amount smaller than the droplet 302 is discharged from the nozzle 11 e.

  That is, the extrusion amount of the ink 300 is L1> L2> L3, and the droplet amount of the ink ejected thereby has a relationship of droplet 301> droplet 302> droplet 303. Therefore, by adjusting the potential difference ratio ΔV2 / ΔV1 of the drive signal P, the amount of droplets of ink ejected from the nozzle 11e can be increased or decreased.

  Moreover, even if the amount of droplets is increased or decreased in this manner, the droplet velocity of the ink does not substantially change. The reason is as follows. Since the potential difference ΔV1 of the drive signal P is constant, the degree of expansion of the volume of the pressure chamber 15 by the first expansion pulse P1 is constant regardless of the droplet amount. Moreover, the second expansion pulse P3 has a function of forcibly separating the ink ejected by the application of the first contraction pulse P2 and cutting the tail of the ejected ink. When the potential difference ΔV2 is large, the ejection energy by the application of the first contraction pulse P2 also increases, but the energy by the application of the second expansion pulse P3 also increases. On the other hand, when the potential difference ΔV2 is small, the ejection energy by the application of the first contraction pulse P2 is also small, but the energy by the application of the second expansion pulse P3 is also small. As a result, the extrusion speed of the ink extruded from the nozzle 11e does not change, and the droplet speed of the ink does not change substantially.

  The inventor confirmed that when the intermediate pulse P6 of the drive signal P is set to the reference potential (potential difference ratio ΔV2 / ΔV1 = 1), the potential difference ΔV1 with respect to the standard droplet amount of ink 3.0 pl ejected. When the voltage is adjusted to increase the potential difference ratio ΔV2 / ΔV1 while maintaining the constant, the droplet velocity discharges a large droplet of up to 4.6 pl (approximately 50% increase) without substantially changing We were able to. On the other hand, similarly, when the voltage is adjusted so that the potential difference ratio ΔV2 / ΔV1 becomes small while maintaining the potential difference ΔV1 constant, the droplet velocity does not substantially change, and the minimum is 1.9 pl (about 40% reduction Was able to eject small droplets of That is, it was possible to control about 2.5 times the amount of droplets from 1.9 pl to 4.6 pl without changing the droplet velocity.

  Therefore, among the plurality of inkjet heads 10A to 10D, the potential difference ratio ΔV2 / ΔV1 of the drive signals P output from the drive circuits 60A to 60D to the inkjet heads 10A to 10D is appropriately adjusted independently. Thus, the amount of droplets can be easily adjusted without changing the droplet velocity of the ink ejected from the nozzle 11 e.

  The drive circuits 60A to 60D independently adjust the potential difference ratio ΔV2 / ΔV1 of the drive signal P in each of the plurality of inkjet heads 10 within the range of 0.8 or more and 1.2 or less by the voltage setting units 61A to 61D. Preferably it is possible. If it is less than 0.8, the ejected ink starts to be scattered, and if it exceeds 1.2, the ejected ink starts to be blurred, and it becomes difficult to stabilize the ejection of the ink in any case. If the potential difference ratio ΔV2 / ΔV1 is in the range of 0.8 or more and 1.2 or less, the ink can be stably ejected in a state in which the droplet velocity does not substantially change.

  In the drive signal P, when the potential differences ΔV2 and ΔV3 are compared, ΔV2> ΔV3. Thus, the ink is not further ejected by the second contraction pulse P4 constituting the cancel pulse.

  The potential difference ratio ΔV3 / ΔV2 between the potential difference ΔV2 and ΔV3 is preferably 0.3 or more and 0.9 or less. Within this range, the reverberation pressure wave generated in the pressure chamber 15 after the application of the first contraction pulse P2 can be effectively suppressed, and the ink can be stably ejected. Suppression of reverberant pressure waves is important in high frequency driving. If it is smaller than 0.3, it is not appropriate as a cancel pulse. The potential difference ratio ΔV 3 / ΔV 2 is more preferably 0.5 or more and 0.9 or less, and most preferably 0.8.

  In the drive signal P, a period T1 from the start end of the first expansion pulse P1 to the start end of the first contraction pulse P2 is preferably 0.45 Tc or more and 0.55 Tc or less. Thereby, the ink can be ejected most efficiently.

  Here, Tc is a vibration cycle of the ink in the pressure chamber 15. This Tc can be expressed, for example, by the following equation.

Tc = 2π [{(Mn × Ms) / (Mn + Ms)} × Cc] ^1/2

  Mn is an inertance at the nozzle 11 e, Ms is an inertance at the ink supply port to the pressure chamber 15, and Cc is a compliance of the pressure chamber 15. The inertance refers to the ease of movement of the ink in the ink flow path, and is the mass of the ink per unit cross-sectional area. The inertance M can be approximated by the following equation.

  M = (ρ × L) / S

  ρ is the ink density, S is the cross-sectional area of the surface of the ink flow path perpendicular to the ink flow direction, and L is the length of the ink flow path.

  When the period from the start of the first expansion pulse P1 to the start of the first contraction pulse P2 is T1, and the period from the start of the first contraction pulse P2 to the start of the second expansion pulse P3 is T2. And T2 / T1 is preferably 0.6 or more and 1.2 or less. Within this range, satellites associated with the ejected ink are suppressed, and the ink can be ejected stably. It is more preferable that it is 0.6 or more and 1.0 or less in that discharge can be performed without lowering the discharge efficiency, and it is more preferable that it is 0.7 or more and 0.9 or less in that stable discharge can be performed with high discharge efficiency.

  Next, a specific aspect in the case where the potential difference ratio ΔV2 / ΔV1 of the drive signal P is adjusted independently for each of the inkjet heads 10A to 10D by the drive circuits 60A to 60D will be described.

  First, the drive circuits 60A to 60D independently adjust the potential difference ratio ΔV2 / ΔV1 of the drive signal P in each of the plurality of ink jet heads 10A to 10D, thereby reducing the droplet amount of the ink ejected from the nozzle 11e. The aspect equalized among several inkjet head 10A-10D is mentioned.

  For example, due to the presence or the like of variations in manufacturing the head between the inkjet heads 10A to 10D, even if the same drive signal is applied, droplets of ink ejected by each of the inkjet heads 10A to 10D Variations in quantity may occur. In this case, as described above, the potential difference ratio ΔV2 / ΔV1 of the drive signal P is independently adjusted in each of the ink jet heads 10A to 10D so that the ink droplet amount becomes uniform. The amount of droplets can be made uniform without substantially changing the droplet velocity between 10D. As a result, high-quality images can be formed with uniform droplet amounts among the inkjet heads 10A to 10D.

  The present invention can also be suitably applied to the case where the physical properties of the ink used for the inkjet heads 10A to 10D include ones that differ among the inkjet heads 10A to 10D. When ink having different physical properties is included among the plurality of inkjet heads 10A to 10D, if the drive signal P having a common voltage value is used for all, the amount of ink droplets may vary, which may affect the image quality. is there.

  Therefore, also in this case, physical properties of the ink jet heads 10A to 10D can be obtained by adjusting the potential difference ratio ΔV2 / ΔV1 of the drive signal P independently as described above, without substantially changing the droplet velocity. The amount of droplets can be made uniform among the different inks, and the influence on the image quality can be reduced.

  Physical properties of the ink include surface tension, specific gravity, viscosity and the like of the ink. Among them, the viscosity of the ink is preferable. This is because the viscosity of the ink greatly affects the droplet amount as compared to other physical properties.

  As the viscosity of the ink increases, the ink is less likely to be pushed out of the nozzle 11 e, and the amount of droplets tends to be smaller. Therefore, it is preferable to increase the potential difference ratio ΔV2 / ΔV1 of the drive signal P as the ink viscosity is higher in the inkjet heads 10A to 10D. As a result, even when using inks with different viscosities, it is possible to make the droplet amount of the ejected ink uniform among the inkjet heads 10A-10.

  Information relating to the physical properties of the ink can be acquired by the input operation unit 107 in accordance with an input instruction from the operator. Further, for example, while information on the physical properties of the ink is provided in each of the ink jet heads 10A to 10D so as to be able to detect the sensor, a sensor (not shown) is provided on the carriage 20 At the time of printing, information related to the physical properties of the ink may be automatically acquired.

  At this time, a table defining the relationship between the potential difference ratio ΔV2 / ΔV1 and the physical properties of the ink is stored, for example, in a memory (not shown) in the drive circuits 60A to 60D, and the physical properties of the ink acquired by the above method It is preferable to set the voltage value of the drive signal P of each of the ink jet heads 10A to 10D in each of the voltage setting units 61A to 61D based on the information related to the above and the table, since rapid adjustment is possible.

  By the way, when adjusting the potential difference ratio ΔV2 / ΔV1 to adjust the droplet amount as described above, the potential difference ΔV1 is maintained constant. When the potential difference ΔV1 of the first expansion pulse P1 is changed, the droplet velocity changes. In other words, when the potential difference ΔV1 of the first expansion pulse P1 is adjusted to be large or small, the droplet velocity of the ink ejected from the nozzle 11e can be changed. Therefore, the drive circuits 60A to 60D adjust the potential difference ΔV1 independently in each of the ink jet heads 10A to 10D, thereby uniforming the droplet speed of the ink ejected from the nozzle 11e with the plurality of ink jet heads 10A to 10D. It is also preferable to

  For example, due to the presence or the like of the time of manufacturing the head between the inkjet heads 10A to 10D, the dispersion of the ink droplet velocity may occur. In this case, normally, the landing position deviation is suppressed by appropriately adjusting the discharge timing of each of the ink jet heads 10A to 10D. However, as described above, the ink jet heads 10A to 10D are adjusted by adjusting the droplet velocity by adjusting the potential difference ΔV1 of the first expansion pulse P1 of the drive signal P to large and small in each of the ink jet heads 10A to 10D. The ink discharge timing can be made uniform between the two.

  When making the droplet velocity uniform among the plurality of ink jet heads 10A to 10D and further making the droplet amount of the ink uniform, after adjusting the potential difference ΔV1 in this way, the adjusted potential difference ΔV1 is maintained The potential difference ratio ΔV2 / ΔV1 may be adjusted as it is.

  Also, the higher the ink viscosity, the slower the droplet velocity of the ejected ink. Therefore, as described above, when the inks used in the inkjet heads 10A to 10D include ones having different viscosities of the ink, variations in droplet velocity may occur between the inkjet heads 10A to 10D. Therefore, by increasing the potential difference ΔV1 of the drive signal P as the ink viscosity is higher among the inkjet heads 10A to 10D, the droplet velocity of the ink ejected from the nozzle 11e can be set to a plurality of inkjet heads 10A to 10D. It is also preferable to make it uniform.

  The adjustment of the droplet amount and the droplet velocity described above is generally carried out in advance based on the result of inspecting the droplet amount and the droplet velocity for each of the ink jet heads 10A to 10D at the time of factory shipment. Further, for example, the operation may be performed each time the operator operates the input operation unit 107. The adjusted voltage values are stored in a memory (not shown) in the drive circuits 60A to 60D, and thereafter, based on the stored adjusted voltage values, the corresponding inkjet heads 10A to 10D from the drive circuits 60A to 60D. The drive signal P is output in response to.

  In the present invention, the amount of ink droplets of the plurality of ink jet heads 10A to 10D is not limited to the case where it is made uniform by independently adjusting the potential difference ratio ΔV2 / ΔV1 of the drive signal P in this manner. The heads 10A to 10D may be made different.

  For example, as in the inkjet recording apparatus 1 shown in the present embodiment, when four inkjet heads 10A to 10D corresponding to four types of YMCK inks are provided, an inkjet that ejects, for example, K (black) ink among them For the head, a drive signal having a potential difference ratio ΔV2 / ΔV1 larger than that of an inkjet head that ejects YMC ink may be applied. As a result, only the K ink can be made into large droplets with respect to the other inks without changing the droplet velocity. This aspect is preferably applicable, for example, when printing a solid image at high speed with a specific color ink.

  Hereinafter, the effects of the present invention will be illustrated by examples.

  When the potential difference ratio ΔV2 / ΔV1 is adjusted by changing the potential difference ΔV2 while maintaining the potential difference ΔV1 constant with respect to the drive signal P shown in FIG. 4 using the inkjet head having the structure shown in FIG. The droplet volume and droplet velocity of ink respectively ejected from the nozzles of

(Inkjet head)
Oscillation period of pressure chamber: Tc = 6 μs
Ink viscosity: 10 cp

(Drive waveform)
T1: 3 μs
T2: 2.5 μs
P5: 2.0 μs
P6: 1.0 μs
P7: 0.5 μs
Drive cycle (start of P1 to end of P4): 8.5 μs
Reference potential: 0 V
ΔV1: 20V
ΔV3: 16V

  The droplet volume was determined by image recognition of a droplet flying by a droplet observation device and converting it to a volume (pl) when the droplet is regarded as one sphere. Further, the droplet amount ratio when the potential difference ratio ΔV2 / ΔV1 was adjusted was determined by the ratio to the droplet volume when ΔV2 / ΔV1 = 1. The results are shown in the graphs of Table 1 and FIG.

  The droplet velocity was obtained by image recognition of the droplet by the droplet observation device, and the distance in which the droplet flies within 50 μs from the position 500 μm away from the nozzle surface was calculated by image processing. The results are shown in Table 1 and FIG.

  As described above, it can be understood that by adjusting the potential difference ratio ΔV2 / ΔV1 of the drive signal P, the droplet amount can be increased or decreased. There was no significant change in droplet velocity by this adjustment, and it was almost constant.

  Next, for the same ink jet head as described above, the ink discharge when the potential difference ratio ΔV3 / ΔV2 when the potential difference ratio ΔV2 / ΔV1 = 1 of the drive signal P shown in FIG. 4 is changed as shown in Table 2 It evaluated about the state. The results are shown in Table 2.

  Next, with respect to the same inkjet head as described above, the ejection state of the ink when T1 / T2 of the drive signal P shown in FIG. 4 was changed as shown in Table 3 was evaluated. The results are shown in Table 3.

1: Ink jet recording apparatus 10, 10A to 10D: Ink jet head 11: Head substrate 11a: nozzle plate 11b: intermediate plate 11c: pressure chamber plate 11d: diaphragm 11e: nozzle 12: wiring substrate 12a: ink supply path 13: adhesive resin Layer 13a: through hole 14: ink manifold 14a: common ink chamber 15: pressure chamber 16: actuator 20: carriage 30: flexible cable 40: guide rail 50: recording medium 60A to 60D: drive circuit 61A to 61D: voltage setting unit 100 Control device 101: Interface controller 102: Image memory 103: Transfer means 103a: Timing generation circuit 103b: Memory control circuit 104: CPU
105: main scanning motor 106: sub scanning motor 107: input operation unit 108: drive signal generation circuit 200: host computer P, Pa, Pb: drive signal P1: first expansion pulse P2: first contraction pulse P3: first Dilation pulse P2: second contraction pulse P5: maintenance pulse P6: intermediate pulse P7: maintenance pulse

Claims (34)

A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio .DELTA.V2 / .DELTA.V1 is configured to be independently adjustable in each of the plurality of ink jet heads, and the potential difference ratio .DELTA.V2 / .DELTA.V1 is independently adjusted in each of the plurality of ink jet heads. An ink jet recording apparatus , wherein the amount of ink droplets ejected is made uniform by the plurality of ink jet heads . The drive circuit is configured to equalize the droplet velocity of the ink ejected from the nozzle by each of the plurality of inkjet heads by adjusting the potential difference ΔV1 independently for each of the plurality of inkjet heads. an ink jet recording apparatus according to claim 1, wherein. A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio .DELTA.V2 / .DELTA.V1 is configured to be adjustable independently for each of the plurality of inkjet heads, and is discharged from the nozzle by adjusting the potential difference .DELTA.V1 independently for each of the plurality of inkjet heads. An ink jet recording apparatus , wherein the droplet velocity of ink is made uniform by the plurality of ink jet heads . A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio ΔV2 / ΔV1 is configured to be independently adjustable in each of the plurality of inkjet heads,
The plurality of inkjet heads include inkjet heads having different physical properties of ink,
The drive circuit makes the droplet amount of the ink ejected from the nozzle uniform by adjusting the potential difference ratio ΔV2 / ΔV1 independently for each of the plurality of ink jet heads with the plurality of ink jet heads. an ink jet recording apparatus characterized by there. The physical property of the ink is the viscosity of the ink,
5. The ink jet recording apparatus according to claim 4, wherein the potential difference ratio ΔV2 / ΔV1 is increased as the viscosity of the ink becomes higher among the plurality of ink jet heads.   Among the plurality of ink jet heads, the drive circuit increases the potential difference ΔV1 as the viscosity of the ink is higher, so that the droplet velocity of the ink ejected from the nozzle is equal to that of the plurality of ink jet heads. The ink jet recording apparatus according to claim 5, wherein the ink jet recording apparatus is uniformized.   The drive circuit is characterized in that the potential difference ratio ΔV 2 / ΔV 1 can be adjusted independently in each of the plurality of ink jet heads within a range of 0.8 or more and 1.2 or less. The inkjet recording device according to any one of 1 to 6. A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio .DELTA.V2 / .DELTA.V1 is configured to be adjustable independently for each of the plurality of inkjet heads, and the potential difference ratio .DELTA.V2 / .DELTA.V1 is in the range of 0.8 or more and 1.2 or less, the plurality of inkjet heads An ink jet printing apparatus, wherein each of the ink jet recording apparatuses is independently adjustable . When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording apparatus according to any one of claims 1 to 8 , wherein / T1 is 0.6 or more and 1.2 or less. A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio ΔV2 / ΔV1 is configured to be independently adjustable in each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 An inkjet recording apparatus characterized in that / T1 is 0.6 or more and 1.2 or less . When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording apparatus according to any one of claims 1 to 8 , wherein / T1 is 0.6 or more and 1.0 or less. A plurality of ink jet heads for expanding and contracting the volume of the pressure chamber corresponding to the actuator by applying a drive signal to the actuator, and discharging the ink in the pressure chamber from the nozzle to print on the recording medium;
An inkjet recording apparatus having a drive circuit for applying a drive signal to the actuators of the plurality of inkjet heads;
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
When the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the drive circuit The ratio ΔV2 / ΔV1 is configured to be independently adjustable in each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 An inkjet recording apparatus characterized in that / T1 is 0.6 or more and 1.0 or less . When the vibration period of the ink in the pressure chamber is Tc, a period T1 from the start end of the first expansion pulse to the start end of the first contraction pulse is not less than 0.45 Tc and not more than 0.55 Tc. The ink jet recording apparatus according to any one of claims 1 to 12 , wherein The ink jet recording apparatus according to any one of claims 1 to 13 , wherein .DELTA.V2> .DELTA.V3 where .DELTA.V3 is a potential difference between the start of the second contraction pulse and the reference potential. The ink jet recording apparatus according to claim 14 , wherein the potential difference ratio ΔV3 / ΔV2 is 0.3 or more and 0.9 or less. The ink jet recording apparatus according to claim 14 , wherein the potential difference ratio ΔV3 / ΔV2 is 0.5 or more and 0.9 or less. The ink jet recording apparatus according to any one of claims 1 to 16 , wherein the drive signal is a slope waveform. By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads ,
By adjusting the potential difference ratio ΔV 2 / ΔV 1 independently in each of the plurality of inkjet heads, the droplet amount of the ink ejected from the nozzle is equalized by the plurality of inkjet heads. Ink jet recording method. In each of the plurality of inkjet heads, by adjusting the potential difference ΔV1 independently claim 18, characterized in that the drop velocity of ink ejected from the nozzle and homogenized with the plurality of inkjet heads The inkjet recording method as described. By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
An ink jet recording method characterized in that the droplet velocity of the ink ejected from the nozzle is made uniform by the plurality of ink jet heads by independently adjusting the potential difference ΔV1 in each of the plurality of ink jet heads. . By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
The plurality of inkjet heads include inkjet heads having different physical properties of ink,
By adjusting the potential difference ratio ΔV 2 / ΔV 1 independently in each of the plurality of inkjet heads, the droplet amount of the ink ejected from the nozzle is equalized by the plurality of inkjet heads. Ink jet recording method. The physical property of the ink is the viscosity of the ink,
22. The ink jet recording method according to claim 21 , wherein among the plurality of ink jet heads, the higher the viscosity of the ink, the larger the potential difference ratio ΔV2 / ΔV1. Among the plurality of inkjet heads, by increasing the potential difference ΔV1 as the viscosity of the ink is higher, the droplet velocity of the ink ejected from the nozzle is made uniform by the plurality of inkjet heads. The ink jet recording method according to claim 22, characterized in that The inkjet according to any one of claims 18 to 23 , wherein the potential difference ratio ΔV2 / ΔV1 is adjusted independently for each of the plurality of inkjet heads within a range of 0.8 or more and 1.2 or less. Recording method. By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
An ink jet recording method, wherein the potential difference ratio ΔV2 / ΔV1 is adjusted independently for each of the plurality of ink jet heads within a range of 0.8 or more and 1.2 or less . When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording method according to any one of claims 18 to 25, wherein / T1 is 0.6 or more and 1.2 or less. By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 And / T1 is 0.6 or more and 1.2 or less . When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 The ink jet recording method according to any one of claims 18 to 25, wherein / T1 is 0.6 or more and 1.0 or less. By applying a drive signal to each actuator of the plurality of inkjet heads, the volume of the pressure chamber corresponding to the actuator is expanded and contracted, and the ink in the pressure chamber is ejected from the nozzle to print on the recording medium In the recording method,
The drive signal includes a first expansion pulse which expands the volume of the pressure chamber starting from a reference potential, a first contraction pulse which contracts the volume of the pressure chamber and discharges ink from the nozzle, and A second expansion pulse that expands the volume of the pressure chamber, and a second contraction pulse that contracts the volume of the pressure chamber and returns to the reference potential in this order,
Assuming that the potential difference between the reference potential and the end of the first expansion pulse is ΔV1 and the potential difference between the start of the first contraction pulse and the end of the first contraction pulse is ΔV2, the potential difference ratio ΔV2 / ΔV1 is , Independently adjusting each of the plurality of inkjet heads,
When the period from the start of the first expansion pulse to the start of the first contraction pulse is T1, and the period from the start of the first contraction pulse to the start of the second expansion pulse is T2, T2 And / T1 is 0.6 or more and 1.0 or less . When the vibration period of the ink in the pressure chamber is Tc, a period T1 from the start end of the first expansion pulse to the start end of the first contraction pulse is not less than 0.45 Tc and not more than 0.55 Tc. The inkjet recording method according to any one of claims 18 to 29 , wherein The ink jet recording method according to any one of claims 18 to 30 , wherein ΔV2> ΔV3 where ΔV3 is a potential difference between the start end of the second contraction pulse and the reference potential. The ink jet recording method according to claim 31 , wherein the potential difference ratio ΔV3 / ΔV2 is 0.3 or more and 0.9 or less. The ink jet recording method according to claim 31 , wherein the potential difference ratio ΔV3 / ΔV2 is 0.5 or more and 0.9 or less. The ink jet recording method according to any one of claims 18 to 33 , wherein the drive signal is a slope waveform.

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