JP3381761B2 - Ink jet recording head, graphic data printing method, and ink droplet ejection ability recovery method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for recording an image or a character on a recording sheet by pressurizing a pressure generating chamber in response to a print signal to eject an ink droplet from a nozzle opening.

[0002]

2. Description of the Related Art In an ink jet recording head, a pressure generating chamber communicating with a reservoir and a nozzle opening is mechanically deformed by a piezoelectric vibrator provided outside, or Joule heat is generated inside. The element vaporizes and pressurizes the ink to eject the ink in the pressure generating chamber from the nozzle opening as an ink droplet, and the ink amount and flight speed of the ink droplet are greatly affected by the fluid characteristics of the ink, particularly the viscosity. That is, in general, the ink jet recording head ejects ink droplets at the reference temperature as shown in FIG. 7 regardless of each mode of graphic printing, text data printing, and solid printing, that is, regardless of the driving frequency of the recording head. Although the ink is configured to be the same in amount, the ink viscosity increases when the environmental temperature changes and the ink temperature falls below the reference temperature. When the amount decreases and rises above the reference temperature, the amount of ink decreases as the drive frequency decreases, and it becomes impossible to form dots of the size corresponding to the target print mode on the recording medium, resulting in poor print quality. There is an inconvenience that it decreases.

[0003]

In order to solve such a problem, it has been proposed to dispose a heater in the vicinity of the recording head to keep the temperature of the recording head and the ink cartridge constant. Since there is a large thermal inertia between the temperature of the ink in the pressure generating chamber, which is the non-control target, it is difficult to precisely control the temperature of the ink in the pressure generating chamber, and the size of the heater is large. As a result, the ink container such as the ink cartridge and the flow path are also heated, and there is a problem that the volatilization of the ink solvent is accelerated. The present invention has been made in view of such a problem, and its object is to set the temperature of the ink in the pressure generating chamber to the print mode without causing an unnecessary temperature rise in the ink container or the flow path. An object of the present invention is to provide an ink jet recording apparatus that can maintain a suitable temperature.

[0004]

In order to solve such a problem, in the present invention, the lid is displaced by the displacement of the pressing means.
A pressure generating chamber pressure of ink through the body, pressure and reservoir for supplying ink through the ink supply port to the generating chamber, a nozzle opening for ejecting pressurized ink by the pressure generating chamber as ink droplets In the ink jet recording head including the above , a heating layer for controlling the ink temperature is formed on the surface of the lid by sputtering or conductive coating .

[0005]

[Function] A heating layer is formed on the lid member that constitutes the pressure generating chamber.
Therefore, the ink in the pressure generating chamber can be maintained at a predetermined temperature and with high accuracy with a response delay that is as small as possible, and an ink droplet of an optimum ink amount for the print mode is ejected.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below with reference to illustrated embodiments. 1, 2 and 3 are
1 shows an embodiment of the present invention, in which a nozzle opening 13
Thickness of the pressure generation chambers 1 formed at the arrangement pitch of 150μ
a spacer 2 made of ceramics of about m, a first cover plate 3 that seals one surface of the spacer 2, and a through hole 4 that connects the ink supply port 12 and the nozzle opening 13 to the other surface,
The pressure generating unit 7 is formed by stacking the second lid 6 having the number 5 on the pressure generating unit 7.

On the other hand, the flow path unit 8 for supplying ink to the pressure generating chamber 1 has a reservoir 9 for supplying ink from an external ink tank, the pressure generating chamber 1 and the nozzle openings 13.
A reservoir forming substrate 11 having a nozzle communicating hole 10 for connecting to the pressure generating chamber 1, an ink supply port 12 for supplying ink to the pressure generating chamber 1, and a nozzle communicating hole 14 connecting the nozzle opening 13 and the pressure generating chamber 1. Ink supply port forming substrate 15
And a nozzle plate 16 having a nozzle opening 13 for ejecting ink droplets are laminated so as to sandwich the reservoir forming substrate 11 in the center, and the above-mentioned pressure generating unit 7,
A plurality of 7, 7 are liquid-tightly fixed on the surface of the ink supply port forming substrate 11 to form a recording head.

In such a structure, each pressure generating chamber 1
A bubble jet type ink jet recording head can be constructed by arranging a Joule heat generating element at the first lid 3, and the first lid 3 is made of a thin plate such as zirconia that is elastically deformable by displacement of the piezoelectric vibrator. A piezoelectric vibrator type ink jet recording head can be constructed by fixing the piezoelectric vibrators 18 on the surface so as to correspond to the respective pressure generating chambers 1. Ink droplets can be ejected from the nozzle openings 13 by applying pressure. Incidentally, reference numeral 19 in the drawing
Indicates a common electrode of the piezoelectric vibrator 18, reference numeral 20 indicates a segment electrode, and reference numeral 21 indicates an ink introduction port of the flow path unit.

In the recording head having the above-mentioned structure, an electric resistance material is sputtered on the surface of a member which comes into contact with the ink, for example, the lid 3, or the heat generating layer 30 is formed by a conductive paint, and the thermistor or the like is used if necessary. A temperature detecting means 31 such as a thermocouple is provided, and can be connected to a power adjusting means 46 and a temperature controlling means 43, which will be described later, by the lead portions 32 and 33, respectively.

FIG. 4 shows an embodiment of a driving device suitable for driving the above-mentioned recording head. The head driving circuit 40 outputs from the host and inputs to the receiving means 41 to print data. The piezoelectric vibrator 1 based on the data converted into data suitable for serial printing by the generation unit 42.
The drive signal is output to the pressure generation means for ejecting ink droplets such as 8 and the level and duration of the drive signal to the piezoelectric vibrator 18 are adjusted by receiving a signal from the print mode control means 47 described later. It is configured to be able to.

The temperature adjusting means 43 is an external temperature sensor 44 for detecting the temperature of the external environment, a set value adjusted by the print mode setting means 45 described later, and a signal from the temperature detecting means 31 provided in the recording head. The power supplied from the power adjusting circuit 46 to the heat generating layer 30 is adjusted based on the above.

The print mode setting means 47 is a print mode setting switch 48 provided on a control panel or the like of the recording apparatus.
Or the print resolution instructed by the host, for example 360
The setting value of the temperature control means 43 can be changed and the head drive circuit 40 can be driven so that the pressure generating means of the recording head can be driven under the conditions suitable for dpi, 720 dpi, and the recording medium such as special paper or plain paper. It is configured to output a control signal for adjusting the level and duration of the drive signal.

In this embodiment, a specific print mode, for example, 3 is set by the host or print mode setting switch 48.
When the mode for printing on plain paper at 60 dpi is selected, the print mode setting means 47 outputs a signal to the temperature control means 43 to adjust the electric power so that the temperature of the ink in the pressure generating chamber 1 becomes 70 ° C. Controlling the power from the circuit 46 to the heating layer 30,
Data for one pixel is printed with two ink drops.

The temperature control means 43 includes an external temperature sensor 44.
Considering the temperature difference between the external temperature and the temperature detection means 31 provided in the recording head, the heat generating layer 30 can be adjusted according to the temperature difference.
The electric power to be supplied to the pressure generating chamber 1 is adjusted to control while suppressing the error amount from the set temperature to be small regardless of the consumption of the ink in the pressure generating chamber 1.

Further, the head drive circuit 40 is 360 dpi.
A drive signal whose level and duration have been adjusted so as to correspond to the drive frequency for printing in 1 above is output to the pressure generating means of the recording head in correspondence with the print data.

On the other hand, when changed to 720 dpi by the host or the host or the print mode setting switch 48, the print mode setting means 47 outputs a signal to the temperature control means 43 and the head drive circuit 40, and the pressure generating chamber 1 Of the heat generation layer 30 from the power adjusting circuit 46 so that the ink of 50
The electric power to the pixel is controlled to print data for one pixel with one dot of ink droplet.

The head drive circuit 40 is 720 dpi.
Level to correspond to the drive frequency by printing in
The drive signal of which the duration is adjusted is output to the pressure generating means of the recording head in correspondence with the print data.

For example, when a drive signal of about 80% of the drive signal level at the time of printing in the printing mode of 360 dpi is applied, the ink amount of the ink droplet becomes the same when printing is performed at the maximum drive frequency, and the density of the solid image becomes Are the same. On the other hand, when the driving frequency is lowered, the amount of ink is reduced.

As described above, when the temperature of the recording head is set higher than the normal temperature, the amount of ink forming the ink droplets becomes
In the area where the drive frequency is reduced, such as graphic printing, the number is small, and it becomes possible to form dots of a small size, preventing color mixture with ink of other adjacent colors, and reducing graininess. Therefore, graphic printing can be performed with high print quality.

Further, the ink temperature is set to be high corresponding to the drive frequency of the recording head, that is, when the ink droplet ejection cycle is long, and set to be low when the ink droplet ejection cycle is short. As a result, it is possible to prevent the ink amount of the ink droplet from varying due to the difference in the driving frequency, and to print with the dots having the same size as the reference temperature.

When the ink droplet ejection capacity changes due to printing for a long time, the heating layer 30 is controlled by the temperature control means 43.
The heating temperature due to is slightly higher than during printing, for example 5 °
The power is controlled so that it becomes higher by about C. As a result, at least the temperature of the ink in the pressure generating chamber 1 rises and the viscosity drops significantly.

In this state, when the drive signal is supplied from the head drive circuit 40 to the pressure receiving means of the recording head by moving the recording head to the ink receiving area of the capping means or the like, the pressure is generated by decreasing the fluid resistance due to the decrease in viscosity. The ink in the chamber 1 can be ejected from the nozzle openings 13 and the ink thickened in the vicinity of the nozzle openings during the printing period can be ejected with a small amount of ink. Further, since the recoverability of the ink droplet ejection capability by the flushing operation is improved, the reliability is improved, and the frequency of the cleaning operation for forcibly discharging the ink by applying the negative pressure to the nozzle opening 13 can be reduced. It is possible to reduce the amount of ink required for the recovery operation.

Although the heating layer 30 is formed on the first lid 3 in the above-mentioned embodiment, the member of the intermediate layer which constitutes the recording head as shown in FIG. Then, on the pressure generating chamber side of the second lid body 6, a heat generating layer 50 is formed by sputtering or the like for each pressure generating chamber, and if necessary, the surface of the heat generating layer 50 is a thin protective layer having ink resistance and heat resistance. Is provided and the end portion of the heat generating layer 50 is drawn out of the pressure generating chamber to form a terminal 51 for supplying heating power.

According to this embodiment, since the ink in the pressure generating chamber 1 can be directly heated by the heat generating layer 50, the temperature of the ink can be controlled with high responsiveness.

[0025] Figure 6, there is shown another embodiment of the present invention, a region that does not participate in the ink ejection, the in the embodiment of this region piezoelectric vibrator faces 1 of the cover 3, a spacer 2 The second lid 6 and, if necessary, the recess 52 that reaches the flow path unit 8 are formed so as to extend in the direction in which the pressure generating chambers are arranged, and the recess 52 is filled with a conductive paint or the like to form the heating element 5.
It is formed so as to be filled with 3, and heating power is supplied from both ends.

According to this embodiment, the heating element 53 is arranged as close to the pressure generating chamber 1 as possible so that the ink in the pressure generating chamber 1 can be maintained at a constant temperature without causing a response delay. The temperature of other channels such as the nozzle openings can be maintained at a temperature suitable for the formation of ink droplets by the conductive heat generated by the members constituting the recording head.

[0027]

As described above, according to the present invention ,
The heating layer is formed on the lid that forms the pressure generating chamber, and the ink in the pressure generating chamber is brought to a predetermined temperature without causing an unnecessary temperature rise in the ink container or flow path, and with a response delay as small as possible. It is possible to maintain a high degree of accuracy, and it is possible to eject an ink droplet having an optimum ink amount for the print mode.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an ink jet recording head of the present invention.

FIG. 2 is a sectional view of one pressure generating unit that constitutes the same recording head.

FIG. 3 is a top view showing an arrangement form of a heat generating layer and a temperature detecting means formed in the pressure generating unit, with the piezoelectric vibrator and the segment electrodes removed.

FIG. 4 is a block diagram showing an embodiment of the recording head driving device of the above.

FIG. 5 is a cross-sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a relative ink amount of ink droplets and a driving frequency in an inkjet recording head, with temperature as a parameter.

[Explanation of symbols]

1 Pressure generation chamber 2 spacer 3 First lid 6 Second lid 7 Pressure generation unit 8 flow path unit 13 nozzle opening 18 Piezoelectric vibrator 30 heating layer 31 temperature detecting means 44 External temperature sensor

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-3-92354 (JP, A) JP-A-63-168364 (JP, A) JP-A-62-77947 (JP, A) JP-A-2- 198845 (JP, A) JP 10-230598 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/045-2/055 B41J 2/01 B41J 2/18- 2/185

Claims (5)

(57) [Claims] 1. A pressure generating chamber for pressurizing ink via a lid in response to displacement of a pressurizing device, a reservoir for supplying ink to the pressure generating chamber via an ink supply port, and the pressure generating chamber. An ink jet recording head comprising a nozzle opening for ejecting a pressurized ink as an ink droplet, wherein an ink temperature control heating layer is formed on the surface of the lid by sputtering or a conductive paint. Recording head. 2. A pressure generating chamber that pressurizes ink via a lid in response to displacement of a pressurizing unit, a reservoir that supplies ink to the pressure generating chamber via an ink supply port, and the pressure generating chamber. In an ink jet recording head comprising a nozzle opening for ejecting pressurized ink as an ink droplet, a heating layer for controlling ink temperature is formed by sputtering or a conductive paint so as to be located on the inner surface of the pressure generating chamber. The inkjet recording head that is made. 3. The ink jet recording head according to claim 1, wherein among the members constituting the ink jet recording head, a temperature detecting means is formed in a member constituting the pressure generating chamber. 4. A pressure generating chamber for pressurizing ink via a lid in response to displacement of a pressurizing unit, a reservoir for supplying ink to the pressure generating chamber via an ink supply port, and the pressure generating chamber. A nozzle opening for ejecting pressurized ink as an ink droplet, and an ink temperature control located on the surface of the lid by sputtering or conductive paint, or on the inner surface of the pressure generating chamber by sputtering or conductive paint. A printing method for printing graphic data by using an ink jet recording head having a heating layer, and keeping the temperature of the ink in the pressure generating chamber higher than a reference temperature by the heating layer. 5. A pressure generating chamber that pressurizes ink via a lid body in response to displacement of a pressurizing unit, a reservoir that supplies ink to the pressure generating chamber via an ink supply port, and the pressure generating chamber. A nozzle opening for ejecting pressurized ink as an ink droplet, and an ink temperature control located on the surface of the lid by sputtering or conductive paint, or on the inner surface of the pressure generating chamber by sputtering or conductive paint. An ink that uses an ink jet recording head having a heat generation layer and that causes the heat generation layer to maintain the temperature of the ink in the pressure generation chamber higher than a reference temperature and eject ink droplets from the nozzle openings regardless of print data. Method for recovering droplet discharge capacity.