JP2000272103A - Ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a printing quality irrespective of a sudden environment change by setting a means for correcting driving signals to discharge ink drops from a recording head based on a temperature change ratio by a temperature sensor which detects an environment temperature. SOLUTION: A thermistor as a temperature sensor 11 for outputting a temperature signal following a change of an environment temperature is set to the vicinity of a recording head 10. A driving signal generation circuit 12 outputs an optimum driving signal to meet the environment temperature on the basis of the temperature signal from the sensor 11, and selectively impresses the driving signal to each piezoelectric vibrator 9 of the head 10 via switching elements S which performs on/off control according to printing signals. A correction circuit 13 operates from the signal of the sensor 11 a change ratio of the environment temperature by a temperature change ratio operation circuit 14, receives a signal from a correction ratio memory means 15 which stores a relationship between the temperature change ratio and a correction ratio, and outputs the correction ratio conforming to the temperature change ratio to the circuit 12.

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 apparatus for printing by discharging ink in a pressure generating chamber provided with a pressurizing means as ink droplets from a nozzle opening, and more particularly to a temperature characteristic correcting technique. .

[0002]

2. Description of the Related Art An ink jet recording apparatus prints because a pressure receiving chamber communicating with a nozzle opening and a pressure generating chamber communicating with a nozzle opening are ejected by applying a pressure by a piezoelectric vibrator or a heating element. The size and flight speed of the ink droplet, which affects the quality, largely depend on the fluid characteristics of the ink. Since the viscosity among the fluid characteristics of the ink greatly depends on the ambient temperature, a temperature sensor is usually arranged near the recording head, and the driving signal is controlled based on the ambient temperature. According to this, when the temperature change rate of the environment is low as indicated by reference numeral A in FIG. 6, the temperature of the recording head also changes substantially following the environmental temperature as indicated by reference numeral B in FIG. Therefore, the level of the drive signal and the application time can be adjusted in accordance with the low and high ink viscosities due to the high and low temperatures, and the print quality can be maintained regardless of the environmental temperature.

[0003]

However, since the thermal time constant of the ink flow path of the recording head and the thermal time constant of the temperature sensor are different from each other, it is not possible to use heating or a cooler as in winter or summer. 6, when the temperature of the environment fluctuates rapidly during the printing operation, the temperature of the recording head cannot follow the temperature of the environment as shown by the symbol D in FIG. There is a problem that the temperature of the path and the temperature of the temperature sensor are diverged and a large temperature difference is generated between the two, and a driving signal far from the fluid characteristics of the ink is applied, so that the printing quality is greatly reduced. The present invention has been made in view of such a problem, and an object of the present invention is to provide an ink jet recording apparatus capable of maintaining print quality regardless of a rapid temperature change in an environment. .

[0004]

According to the present invention, there is provided a pressure generating chamber which communicates with a common ink chamber and a nozzle opening and is pressurized by a pressurizing means. A print head that ejects ink droplets from the nozzle openings in accordance with a drive signal, a temperature sensor that detects an environmental temperature, and that corresponds to external print data and is suitable for the environmental temperature detected by the temperature sensor An ink jet recording apparatus comprising: a driving signal generating unit that generates a driving signal; and a correction unit that corrects the driving signal based on a temperature change rate by the temperature sensor.

[0005]

When the temperature of the environment changes rapidly, the drive signal is corrected at a correction rate corresponding to the change rate of the environmental temperature, and a drive signal corresponding to the actual temperature of the print head is supplied to the print head.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 1 shows an embodiment of an ink jet recording head to which the present invention is applied by a structure near one pressure generating chamber.
Is a nozzle plate having a nozzle opening 2, 3 is a flow path forming plate that forms a pressure generating chamber 4, an ink reservoir 5, and an ink supply port 6 that connects the pressure generating chamber 4 and the ink reservoir 5. The nozzle plate 1, the flow path forming substrate 3, and the elastic plate 7 are liquid-tightly stacked to form a flow path unit 8.

The flow path unit 8 receives the displacement of the piezoelectric vibrator 9 in the axial direction, pressurizes the ink in the pressure generating chamber 4 and discharges it as ink droplets from the nozzle opening 2, or via the ink supply port 6. The ink in the reservoir 5 is sucked into the pressure generating chamber 4.

FIG. 2 shows an embodiment of a driving device for driving the recording head 10 described above. A temperature sensor is provided near the recording head 10 and outputs a temperature signal following a change in environmental temperature. 11, for example, a thermistor is arranged. The drive signal generation circuit 12 is configured to output an optimum drive signal corresponding to the environmental temperature based on the temperature signal from the temperature sensor 11, and the drive signal from this is switched on / off by a print signal. It is selectively applied to each piezoelectric vibrator 9 of the recording head 10 via the element S.

As shown in FIG. 3 (a), the applied pressures are the voltages V1, V2, V3 applied to the piezoelectric vibrator as well known, and the change rates α1, α2 as shown in FIG. 3 (b). , Α3, or by simultaneously adjusting the voltage and the rate of change.

The correction circuit 13 comprises a temperature change rate calculation circuit 14 for calculating a change rate of the environmental temperature based on a signal from the temperature sensor 11, and a correction rate storage means 15 storing the relationship between the temperature change rate and the correction rate. And outputs a correction rate corresponding to the temperature change rate to the drive signal generation circuit 12.

As shown in Table 1, the correction rate storage means 15 is configured to store a correction rate having a smaller value as the temperature change rate is larger.

[Table 1]

In this embodiment, when the temperature change is small, a signal having a correction factor of 1 is output from the temperature change correction circuit 13, so that the drive signal generation circuit 12
Output the optimal drive signal for the environmental temperature detected by
This drive signal is applied to the piezoelectric vibrators 9, 9, 9,... Via the switching element S in response to the print signal.

Accordingly, the pressure generating chamber 4 is pressurized with an environmental temperature, that is, a pressure that is optimal for the temperature of the ink in the recording head 10, so that high quality can be achieved without being affected by the fluid characteristics of the ink due to the environmental temperature. Is executed.

On the other hand, if the heating equipment is used during printing in winter or the cooler is used in summer and the environmental temperature changes rapidly, the temperature change rate calculation circuit 14 calculates the temperature change rate. A correction rate corresponding to the change rate, that is, a low correction value when the temperature change rate is high, and a correction value close to 1 when the temperature change rate is small are read from the correction rate storage unit 15. Is output to the drive signal generation circuit 12.

Thus, the drive signal generation circuit 12 outputs a drive signal corresponding to the temperature detected by the temperature sensor 11 before the time ΔT before the current time, that is, a drive signal in consideration of a delay in the thermal response of the recording head 10. Will do.
Therefore, even if the recording head 10 has a larger heat capacity than the temperature sensor 11 and has a low follow-up property with respect to the environmental temperature, a drive signal suitable for the ink temperature of the recording head 10 is applied.

FIG. 4 shows another embodiment of the present invention. In this embodiment, there is provided a history storage means 16 for storing a history of temperature changes, and the temperature of the recording head 10 is changed in the past temperature change. Is configured to store a temperature change within a range affected by

According to this embodiment, the drive signal can be adjusted in consideration of not only the current temperature change rate but also the history of the temperature that the recording head 10 has received in the past. Even when printing is restarted in a state where the temperature is not completely balanced with the current environmental temperature while leaving the influence of the temperature, it is possible to supply a drive signal according to the actual temperature of the recording head 10. .

FIG. 5 shows another embodiment of the present invention. In this embodiment, a signal from the temperature sensor 11 is passed through a time constant circuit 17 which matches the temperature time constant of the recording head 10. And outputs the signal to the drive signal generation circuit 12.

According to this embodiment, the temperature signal from the temperature sensor 11 is output to the drive signal generation circuit 12 by the time constant circuit 16 with the same time constant as that of the recording head, and therefore, is related to the change speed of the environmental temperature. Therefore, it is possible to output an optimal drive signal that matches the temperature of the recording head 10.

In the above-described embodiment, a recording head using a piezoelectric vibrator as the pressurizing means has been described. However, a so-called heating means is housed in a pressure generating chamber to vaporize ink to generate a discharge pressure. The same effect is achieved when applied to a bubble type recording head.

[0021]

As described above, according to the present invention, the correction means for correcting the drive signal based on the temperature change rate by the temperature sensor is provided. A drive signal corresponding to the temperature can be applied, and printing can be performed with high print quality by pressurizing the ink with a pressing force that matches the fluid characteristics of the ink.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an ink jet recording head used in an ink jet recording apparatus of the present invention.

FIG. 2 is a block diagram showing one embodiment of the ink jet recording apparatus of the present invention.

FIGS. 3A and 3B are diagrams illustrating an example of a drive signal. FIG.

FIG. 4 is a block diagram showing one embodiment of the ink jet recording apparatus of the present invention.

FIG. 5 is a block diagram showing one embodiment of the ink jet recording apparatus of the present invention.

FIG. 6 is a diagram showing the followability of the temperature of the inkjet recording head to a change in the temperature of the environment.

[Explanation of symbols]

 10 Inkjet recording head 11 Temperature sensor

Claims (4)

[Claims] A pressure generating chamber which communicates with a common ink chamber and a nozzle opening and is pressurized by a pressurizing means;
A recording head that ejects ink droplets from the nozzle openings in accordance with a drive signal, a temperature sensor that detects an environmental temperature,
A drive signal generating unit for generating a drive signal suitable for the environmental temperature detected by the temperature sensor, the drive unit corresponding to print data from the outside, and an environmental temperature detected by the temperature sensor. An ink jet recording apparatus comprising: a correction unit that corrects the drive signal based on a rate of change. 2. The temperature control device according to claim 1, wherein said correction means includes a temperature change rate calculation means for calculating a temperature change rate based on a signal from said temperature sensor, and a correction rate storage means for storing a correction rate corresponding to said temperature change rate. The ink jet recording apparatus according to claim 1, wherein: 3. The ink jet recording apparatus according to claim 2, wherein said correction means has a history storage means for storing a temperature history of an environmental temperature. 4. A pressure generating chamber which communicates with a common ink chamber and a nozzle opening and is pressurized by pressurizing means.
A recording head that ejects ink droplets from the nozzle openings in accordance with a drive signal, a temperature sensor that detects an environmental temperature,
A drive signal generating means for generating a drive signal suitable for the environmental temperature detected by the temperature sensor in response to external print data, wherein the signal from the temperature sensor is An ink jet recording apparatus which outputs to the drive signal generating means via a time constant circuit corresponding to a thermal time constant of the head.