JPH11138798A - Ink-jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid undesired effects on an image by the change of ink viscosity due to temperature by applying pressure to a liquid receiving chamber by a driving signal from a driving signal generation means and forming a heating signal on the basis of the measurement results of the temperature of heads by a temperature measuring means. SOLUTION: The temperature of the neighborhood of a head 17 is measured by a thermistor 19, and a wave form is changed corresponding to a measured temperature so that heads can be driven corresponding to the change of ink viscosity due to temperature. Since the amplitude of the heating wave form of each head can be controlled independently on the basis of temperature measurement signal by the thermistor 19, the temperature of an ink of each color of YMCK is controlled to be uniform. As a result, the undesired effects on an image by the change of ink viscosity due to temperature can be avoided while the constitution of the heads being controlled not to be complex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly, to an ink jet printer which can be used as a hard copy device for recording image data from a computer or the like by discharging ink.

[0002]

2. Description of the Related Art Conventionally, in a printer which performs printing using binary gradation data, a plurality of printing elements provided in a printing head perform ON / OFF printing according to binary data. .

For example, in an ink jet printer, each nozzle is one in a print head having a plurality of ejection nozzles.
The image data for each ejection is transferred to the drive IC of the head each time, and the transferred image data is used to eject ink to form an image.

FIG. 12 is an explanatory view schematically showing a waveform of a drive signal supplied to a head and a state of discharge of a droplet by a discharge nozzle. As shown in FIG. 12, the ejection nozzle constituted by a piezo element or the like expands (→) according to the drive signal waveform, and then contracts to eject the ink droplet (), and returns to the original state again ( ) Is repeated.

[0005] In recent years, gradation printing has been performed by various printers, and ink-jet printers have been performed similarly to other printers. As one of the gradation recording, there is a method of changing the number of dots ejected for one pixel. According to this method, by changing the number of dots to be ejected, an effect equivalent to changing the size of dots during ejection can be obtained.

[0006]

However, if the viscosity of the ink changes due to a change in temperature, there may be a case where sufficient ejection cannot be performed. In such a case, ink ejection is not performed with high accuracy, and image quality is degraded.

In general, the viscosity doubles for every 10 ° C. decrease in temperature. For this reason, when the inkjet printer is used in a low-temperature environment such as in the early morning of winter, sufficient ink cannot be ejected for a while after the start of use.

Further, even if the ink jet printer is warmed up after the start of use, the ink of the color not used is not discharged sufficiently because the temperature does not rise.

[0009] Further, the head is brought into an air-cooled state by the movement of the head, so that the temperature of the ink of the unused color tends to decrease. Also, for the ink used,
When the cooled ink passes through the nozzles, the entire head is in a water-cooled state, and the temperature does not easily rise.

Due to such a problem, Japanese Patent Laid-Open Publication No.
Japanese Patent No. 3062 proposes to heat ink by providing a heater near the head of an inkjet printer.

However, when the heater is provided in this manner, the number of components near the head increases, and the configuration becomes complicated. It is difficult to control the heating of the ink in the liquid storage chamber of the head over a wide range. The efficiency of heating and controlling the ink in the liquid storage chamber of the head over a wide range is poor. Power consumption by the heater resistor is large. There is a problem.

Further, in an ink jet printer having heads for a plurality of colors for forming a color image, there is a problem that the color balance is lost if the temperatures of the heads do not substantially match. And even if the above-described heating control by the heater is used, it is extremely difficult to keep the temperature of the head of each color uniform.

The present invention is intended to solve such a problem, and it is possible to prevent a change in ink viscosity due to a temperature from affecting the image while suppressing the structure of the head from becoming complicated. The present invention provides a simple inkjet printer.

[0014]

Accordingly, the invention as a means for solving the problem is described below.

According to a first aspect of the present invention, there is provided an ink jet printer for recording an image by ejecting ink droplets from a nozzle tip of a head, wherein a drive signal for ejecting ink is provided based on image information. Drive signal generating means for generating, piezoelectric means for applying pressure to the liquid storage chamber by the drive signal, temperature measuring means for measuring the temperature of the head, and the piezoelectric means based on a measurement result by the temperature measuring means. And a heating signal generating means for generating a heating signal for heating the ink in the liquid storage chamber by generating heat due to vibration in the ink jet printer.

That is, according to the invention of the ink jet printer, heat is transmitted from the piezoelectric means heated by the heating signal applied to the piezoelectric means, so that droplets are not ejected from the tip of the nozzle and the liquid storage chamber adjacent to the piezoelectric means is discharged. Is heating the ink.

Therefore, since the piezoelectric means for discharging the ink is also used for heating the ink, it is possible to suppress the complication of the configuration of the head and to change the image due to the change in the ink viscosity due to the temperature. Can be avoided.

(2) The invention according to claim 2 is characterized in that (1)
Wherein the heating signal generating means generates a heating signal during non-recording. That is, according to the invention of the ink jet printer, the liquid storage adjacent to the piezoelectric means can be performed without discharging droplets from the nozzle tip during non-recording by heat conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means. Heating ink in the room.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed at the time of non-recording. Therefore, the temperature of the head is suppressed while the structure of the head is not complicated. It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to the change.

(3) The invention according to claim 3 is characterized in that:
Wherein the heating signal generating means generates a heating signal when the head is outside the image forming area. That is, according to the invention of the ink jet printer, when the head is located outside the image forming area, the droplet is not ejected from the tip of the nozzle by the heat conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means. Heating the ink in the liquid storage chamber adjacent to the piezoelectric means.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed when the head is outside the image forming area, so that the structure of the head is complicated. It is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature while suppressing this.

(4) The invention according to claim 4 is characterized in that (1)
In (3), the heating signal generating means controls the amplitude of the heating signal based on the measurement result of the temperature measuring means.

That is, according to the invention of the ink jet printer, the heat is transmitted from the piezoelectric means heated by the heating signal whose amplitude changes in accordance with the temperature, so that the droplet is not discharged from the tip of the nozzle and is adjacent to the piezoelectric means. The heated ink in the liquid storage chamber is heated.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed by the heating signal whose amplitude is controlled, so that the structure of the head is complicated. It is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature while suppressing.

In this case, since the amplitude is proportional to the energy, increasing the amplitude increases the energy for heating. Therefore, by controlling the amplitude of the heating signal, fine temperature adjustment and rapid heating can be performed.

(5) The invention according to claim 5 is characterized in that (1)
In (3), the heating signal generation means controls the frequency of the heating signal based on the measurement result of the temperature measurement means.

That is, according to the invention of the ink jet printer, the heat is transmitted from the piezoelectric means which is heated by the heating signal whose frequency changes in accordance with the temperature, so that the droplet is not ejected from the tip of the nozzle and adjacent to the piezoelectric means. The heated ink in the liquid storage chamber is heated.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed by the heating signal whose frequency is controlled, so that the structure of the head becomes complicated. It is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature while suppressing.

In this case, since the frequency is proportional to the energy, increasing the frequency increases the energy for heating. Therefore, by controlling the frequency of the heating signal, fine temperature adjustment and rapid heating can be performed.

(6) An ink jet printer according to a sixth aspect of the present invention is an ink jet printer that performs image recording by discharging ink droplets from nozzle tips of a plurality of heads. Signal generating means for generating a driving signal for the same, piezoelectric means for applying pressure to the liquid storage chamber of each head by the driving signal, temperature measuring means for measuring the temperature of each of the plurality of heads, and the temperature measuring means Heating signal generating means for generating a heating signal for heating the ink in the liquid storage chamber by generating heat due to vibration by the piezoelectric means of each head based on the measurement result in And a control unit for selectively applying any one of the heating signal and the heating signal to the piezoelectric unit.

That is, according to the invention of the ink jet printer, heat is transmitted from the piezoelectric means heated by the heating signal applied to the piezoelectric means, so that droplets are not ejected from the tips of the nozzles of the plurality of heads and the piezoelectric means are adjacent to the piezoelectric means. The heated ink in the liquid storage chamber is heated.

Therefore, since the piezoelectric means for discharging the ink is also used for heating the ink, it is possible to suppress the complexity of the structure of each head and to control the image due to the change in the ink viscosity due to the temperature. Can be avoided.

(7) The invention according to claim 7 is characterized in that:
Wherein the control means selects the heating signal in accordance with the image information and applies the selected signal to the piezoelectric means.

That is, according to the invention of the ink jet printer, in accordance with image information, heat is transmitted from the piezoelectric means heated by the heating signal applied to the piezoelectric means, and the piezoelectric means is not discharged from the nozzle tip without discharging droplets from the nozzle tip. Heats the ink in the liquid storage chamber adjacent to.

In this case, even if any one of the heads is recording, the other non-recording heads can be heated by vibration according to the image information. Therefore, the piezoelectric means for discharging the ink can be used also for heating the ink, and since the heating is performed when each head is not printed, while suppressing the complexity of the head configuration,
It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to temperature.

(8) The invention according to claim 8 is characterized in that:
Wherein the control means selects the heating signal and applies it to the piezoelectric means when the image information is a signal indicating non-recording.

That is, according to the invention of the ink jet printer, in accordance with the image information, the heat is transmitted from the piezoelectric means which is heated by the heating signal applied to the piezoelectric means, so that the piezoelectric means is not discharged from the nozzle tip without discharging the droplets. Heats the ink in the liquid storage chamber adjacent to.

In this case, even when one of the heads is recording, the other non-recording heads can be heated by vibration in accordance with the image information indicating non-recording. Therefore, the piezoelectric means for ejecting the ink can be used for heating the ink, and the heating is performed when each head is not printed based on the non-printed image information. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature, while suppressing the occurrence of a change in ink viscosity.

(9) The ninth aspect of the present invention is the above (6).
Wherein the control means selects a heating signal during non-recording and applies the selected signal to the piezoelectric means. In other words, according to the invention of the ink jet printer, the heat is transmitted from the piezoelectric means heated by the heating signal applied to the piezoelectric means, so that the liquid droplets are not ejected from the nozzle tip when the respective heads are not recording, and are not adjacent to the piezoelectric means. The heated ink in the liquid storage chamber is heated.

In this case, even if one of the heads is recording, the other non-recording head can be heated by vibration. Therefore, the piezoelectric means for ejecting the ink is also used for heating the ink, and since the heating is performed when each head is not printed, the temperature of the head is suppressed while the structure of the head is not complicated. It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to the change.

According to a tenth aspect of the present invention, in the above (6), the control means selects a heating signal and applies it to the piezoelectric means when the head is outside the image forming area. Features.

That is, according to the invention of the ink jet printer, when each head exists outside the image forming area, droplets are discharged from the nozzle tip by heat conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means. The ink in the liquid storage chamber adjacent to the piezoelectric means is heated without discharging.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and since the heating is performed when each head is outside the image forming area, the configuration of each head is complicated. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature, while suppressing the occurrence of a change in ink viscosity.

(11) In the invention according to claim 11, in the above (6) to (10), the heating signal generating means controls the amplitude of the heating signal based on the measurement result of the temperature measuring means. It is characterized by doing.

That is, according to the ink jet printer of the present invention, the heat is transmitted from the piezoelectric means which is heated by the heating signal whose amplitude changes in accordance with the temperature, so that the droplets are not ejected from the nozzle tip and the piezoelectric of each head is ejected. The ink in the liquid storage chamber adjacent to the means is heated.

Therefore, the piezoelectric means for discharging ink is also used for heating the ink, and heating is performed by a heating signal whose amplitude is controlled for each head. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature while suppressing complication.

In this case, since the amplitude is proportional to the energy, increasing the amplitude increases the energy for heating. Therefore, by controlling the amplitude of the heating signal, it is possible to perform fine temperature adjustment and rapid heating for each head.

(12) In the invention according to claim 12, in the above (6) to (10), the heating signal generating means controls the frequency of the heating signal based on the measurement result of the temperature measuring means. It is characterized by doing.

That is, according to the ink jet printer of the present invention, the heat is transmitted from the piezoelectric means which is heated by the heating signal whose frequency changes in accordance with the temperature, so that the droplets are not ejected from the tip of the nozzle and the piezoelectric of each head is ejected. The ink in the liquid storage chamber adjacent to the means is heated.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and heating is performed by a heating signal whose frequency is controlled for each head. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature while suppressing complication.

In this case, since the frequency is proportional to the energy, increasing the frequency increases the energy for heating. Therefore, by controlling the frequency of the heating signal, it is possible to perform fine temperature adjustment and rapid heating for each head.

(11) In each of the inventions (1) to (10), not only the piezoelectric means but also the driver IC for generating the heating signal is heated in the same manner as the piezoelectric means. The ink is also heated by heat conduction.

[0053]

Embodiments of the present invention will be described below with reference to the drawings. <Mechanical Configuration of Inkjet Printer> First, a mechanical configuration near the head, which is a main part of the inkjet printer 1, will be described with reference to FIG.

The carriage 2 is a resin case in which a head 17 and a head driver 16 described later are housed. The head driver 16 housed in the carriage 2 is constituted by an IC, and is connected to the control board 9 by a flexible cable 5 pulled out from the carriage 2.

The carriage 2 is reciprocated by the carriage drive mechanism 6 in the main scanning direction indicated by the arrow X in the figure.
The carriage drive mechanism 6 includes a motor 6a, a pulley 6b, a toothed belt 6c, and a guide rail 6d, and the carriage 2 is fixed to the toothed belt 6c.

When the pulley 6b is rotated by the motor 6a, the carriage 2 fixed to the toothed belt 6c is moved in the direction of arrow X in the figure. Guide rail 6
d is two parallel cylinders, which penetrate through the insertion hole of the carriage 2 so that the carriage 2 slides.

For this reason, the toothed belt 6c is
The carriage 2 does not bend under its own weight, and the direction of the reciprocating movement of the carriage 2 is on a straight line. The direction in which the carriage 2 moves can be changed by reversing the rotation direction of the motor 6a, and the moving speed of the carriage 2 can be changed by changing the number of rotations.

The ink cartridge 4 has an ink tank inside. The ink supply port of the ink tank is opened when the ink cartridge 4 is set on the carriage 2 and connected to the ink supply pipe. When the connection is released, the ink supply port is closed and the ink is supplied to the head 17.

The carriage 2 is provided with a head 17. Here, a state in which four color heads 17 are provided is shown. An ink cartridge containing Y, M, C, and K inks for ejection can be attached to and detached from the back surface of the head 17. In FIG. 3, illustration of the ink cartridge is omitted.

The flexible cable 5 is connected to a data transfer means, and a flexible film is provided with a data signal line,
A printed wiring pattern including a power line and the like is used to transfer data between the carriage 2 and the control board 9 and follow the movement of the carriage 2.

The encoder 7 is provided with graduations at a predetermined interval on a transparent film of resin. The graduations are detected by an optical sensor provided on the carriage 2 and
The moving speed of the is detected.

The paper transport mechanism 8 is a mechanism for transporting the recording paper P in the sub-scanning direction indicated by the arrow Y in the figure.
It is configured to include a pair of transport rollers 8b and 8c. The transport roller pair 8b and the transport roller pair 8c are driven by the transport motor 8a, and are a pair of rollers that are substantially equal by a gear train (not shown), but rotate at a slightly higher peripheral speed.

The recording paper P is sent out from a paper feeding mechanism (not shown) and is nipped by a pair of conveying rollers 8b rotated at a constant speed, and is conveyed in a sub-scanning direction by a paper feeding guide (not shown). Is corrected and then conveyed while being nipped by the conveying roller pair 8c.

Since the peripheral speed of the pair of conveying rollers 8c is extremely slightly higher than that of the pair of conveying rollers 8b, the recording paper P passes through the recording section without causing slack. The speed at which the recording paper P moves in the sub-scanning direction is set to a constant speed.

While moving the recording paper P at a constant speed in the sub-scanning direction in this way, the carriage 2 is moved at a constant speed in the main-scanning direction, and the ink ejected from the head 17 is attached to one side of the recording paper P. The image is recorded in a predetermined range of the image.

In the above configuration, the configuration of the head 17 is as shown in FIG. FIG. 4A illustrates a head having five discharge nozzles for the sake of explanation, but in actuality, the head is configured to have a larger number of discharge nozzles.

As described above with reference to FIG. 12, the piezo element 1 for ejecting ink droplets by expansion and contraction is used.
7p is provided on the head 17 corresponding to each ejection nozzle. Further, a driver IC 17d for supplying a driving signal and a heating signal to the piezo element 17p is disposed on the ink flow path (ink reservoir).

This piezo element is an example of the piezoelectric means of the present invention. Although there are various types of piezoelectric means, a description will be given of a piezo element as an example in the present embodiment.

A thermistor 19 is provided on the discharge nozzle near the piezo element 17p, and constitutes a temperature measuring means. Note that the one shown in FIG. 4 relates to a head of a certain color. In a color ink jet printer, a plurality of heads having the same configuration are provided on the carriage 2 corresponding to a plurality of color inks. And

<Electrical Configuration of Inkjet Printer> Next, the electrical configuration of the inkjet printer will be described. FIG. 1 is a block diagram showing an example of the overall configuration of an ink jet printer according to an embodiment of the present invention. FIG. 2 is a block diagram showing a main part of FIG. 1 in detail.

In FIG. 1, the control board 9 indicated by a broken line
Is mounted with a CPU 11 as control means for controlling the entire inkjet printer 1, and is connected to the head driver 16 of the carriage 2 by the flexible cable 5 as described above.

The page memory 12 stores image data received from a personal computer or the like that uses the inkjet printer 1 as a peripheral device. The storage capacity of the page memory 12 is determined by the number of bits, the number of dots, and the number of gradation image data handled by a personal computer or the like.
It may be determined according to the signal transfer speed, the processing speed of the CPU, and the like.

The line memories 13a and 13b are used as line memories for storing image data of each pixel which is recorded in a line in the main scanning direction when recording on the recording paper P, and each image data has several bits. Is transferred from the page memory 12 with the gradation data of In this embodiment, two line memories 13a and 13b for 6-bit processing are used in parallel, but one line memory for 12-bit processing may be used.

The data signal line (data BUS) from the page memory 12 has 12 bits, and each line memory 13 has 6 bits.
Branched bit by bit. Line memories 13a and 13
The image data b is transferred to the head driver 16 via the flexible cable 5.

The interfaces 14a and 14b are means for transmitting and receiving data to and from an external personal computer, and are constituted by any of various serial interfaces and various parallel interfaces.

The head drivers 16a to 16d are constituted by ICs, and in this embodiment, one head driver 16a to 16d is provided for each of the four colors of YMCK. Each head driver is connected to a 128-bit × 3 shift register, and image data from the line memories 13a and 13b is temporarily stored in the shift register. This shift register will be described later.

It is to be noted that a plurality of head drivers 16 may be provided for each color, and further downsizing can be achieved by packaging drivers for four colors in one IC. The head driver 16 has a 3-bit data signal line. When the head driver 16 is serially connected by this signal line, image data that could not be stored in the previous shift register is stored in the subsequent shift register. it can.

Four-color head 17 according to the recording means of the present invention
Y, 17M, 17C, and 17K each have 128 discharge nozzles (hereinafter simply referred to as nozzles),
The nozzles constituting each head are arranged in the sub-scanning direction so that a plurality of lines can be simultaneously recorded.

In this embodiment, the yellow (Y) image data is transferred from the line memory 13a to the head driver 16a via a 3-bit data signal line. Then, the 128 yellow image data transferred to the head driver 16a are processed in parallel, and recording by the head 17Y is executed.

Similarly, the magenta (M) image data is transferred from the line memory 13a to the head driver 16b, and the recording is executed by the head 17M. The cyan (C) image data is transferred from the line memory 13b to the head driver 16b.
c and the recording by the head 17C is executed.
The black (K) image data is transferred from the line memory 13b to the head driver 16e, and recording is performed by the head 17K. The detailed operation of these head drivers 16 will be described later.

The AND gate 18 controls the TRGIN signal for starting the ink ejection when the carriage 2 starts one reciprocating movement and reaches a predetermined position on the outward path based on the information detected by the encoder 7. The data is output to the head driver 16 via the circuit 23. The head driver 16 receives this TRGIN signal and sends out a drive signal,
Of the ink is performed.

Each of the head drivers 16a to 16d is connected to the head 17Y by a 128-bit data signal line.
A drive signal is supplied to the piezo elements provided for the respective nozzles of up to 17K, and the piezo elements are deformed in response to the drive signal, whereby ink in the head of each color is ejected.

In general, an ink jet printer performs recording by discharging ink droplets from nozzles in accordance with a drive signal. The ink droplets are sequentially recorded on the recording paper P, so that an area corresponding to the number of droplets can be recorded, and gradation recording can be performed.

By increasing the driving voltage of the piezo element, the speed of the droplet discharged from the nozzle head 17 can be increased. Then, it becomes possible to catch up by the time a droplet ejected after the droplet ejected first lands on the recording medium. With this, a plurality of droplets can be landed at one time or landed at one place.In the case of a method of performing gradation expression by changing the number of droplets, a plurality of droplets are landed separately. The resolution can be increased than the resolution. That is, if the applied voltage of each ejection is gradually increased for each pulse, sequentially ejected ink droplets can be recorded at a closer position on the recording paper P, and higher-quality gradation recording can be performed. .

Further, by using different waveforms for the drive signal depending on the environment around the ink jet printer 1,
Stable image quality can be obtained. In this embodiment, the temperature around the head 17 is measured by the thermistor 19, and the waveform is changed according to the measured temperature. With this configuration, even when the ink viscosity changes due to the temperature, the head can be driven correspondingly. It is more preferable that the humidity condition and the like be parameters for changing the waveform of the drive signal.

In order to change the waveform of the drive signal each time one droplet of ink is ejected and also in accordance with the environment, various waveforms of the drive signal are stored in a line memory (not shown) in the drive waveform generating circuit 15. Stored as digital data. This line memory can be configured using an SRAM or the like.

The line memory stores, for each temperature condition, waveform data of a drive signal in which the applied voltage is gradually increased for each pulse. In this embodiment, 3 bits per color (8
(Gray scale) data, the waveform data stored in the line memory is a digital data of a waveform that is repeated eight times by gradually increasing the amplitude of the basic waveform.

Note that, here, 3 bits (8 gradations) are taken as an example, but other values are also possible, and the number of bits of each data (the number of gradations) and the data of the line memory are linked together. You can change it.

The CPU 11 calculates the optimum waveform data for the temperature condition detected by the thermistor 19 and sends it to the drive waveform generating circuit 15. The drive waveform generating circuit 15 demodulates and amplifies the waveform data of the drive signal into an analog waveform by D / A conversion, and outputs the analog waveform to the head drivers 16a to 16d.

<Electrical Configuration of Driver of Inkjet Printer> Next, the head driver shown in FIG. 2 will be described in detail with reference to a block diagram. Although the configuration of the head driver 16a and the head 17Y is shown here, the head drivers 16b to 16d and the heads 17M to 17K have the same configuration.

The head driver 16 of this embodiment includes a shift register 31, a latch 32, a digital comparator 33, a selection gate 34, a level shifter 35, and a driver 3.
6, including a counter 37 and the like.

In this embodiment, in order to process image data having eight gradations per pixel, the head driver 16 is used.
Has a configuration corresponding to 3 bits. From the line memory 13, gradation image data in which one pixel has a plurality of bits, in this case, three bits, is serially transferred to the head driver 16a in pixel units. In FIG. 2, the first 3-bit pixel data DAT0, DAT
1, a state where DAT2 is being transferred through a 3-bit data signal line.

The shift register 31 has a capacity capable of storing image data of a number of pixels corresponding to one ejection of the nozzle head 17. In the present embodiment, image data for 128 pixels arranged in the sub-scanning direction is stored. When the carriage 2 reaches a position suitable for printing, the control circuit 23
The latch 32 outputs the OAD signal, and upon receiving the LOAD signal, latches the image data output in parallel from the shift register 31.

The digital comparator 33 operates according to the comparing means of the present invention, and compares the value of the image data latched by the latch 32 with the count value of the counter 37. In this example, since the image data is 3 bits per pixel,
It was a 3-bit counter. A counter corresponding to the number of bits of the image data may be appropriately used as the counter as the comparing means.

Here, it is assumed that the digital comparator 33 and the counter 37 are circuits for changing the latched 3-bit data to a pulse width. The counter 37
A counter that counts up independently for each ejection interval from the reset signal RST and compares it with the input data. As a result, the output of the comparator 33 keeps the H level until the number of ejections in proportion to the data. That is, the ejection number interval selection gate comparable to the gradation data is opened, that is, the ink droplets are ejected that number of times.

When the value of the image data is equal to or greater than the value obtained by subtracting 1 from the count signal, the digital comparator 33 sets Hi.
The level is output, and the value of the image data is 1 from the count signal.
When it is less than the value obtained by subtracting, a low level is output, and the state of the output is maintained until the comparison result changes. The digital comparator 33 converts the parallel data of a plurality of bits into continuous 1-bit data that is serial data.

The selection gate 34 divides each nozzle of the head 17 into two groups of odd-numbered and even-numbered nozzles, and performs switching for sequentially driving the nozzles. The selection gate 34 sets the AND gate to 12
The output terminals of each digital comparator 33 are connected to one of the input terminals in parallel with the eight input terminals, and the other input terminal is connected to a control circuit.

Here, X and Y are selection signals for selectively using the nozzles of the head 17 for recording, and are output from the control circuit 23. In the present embodiment, the recording means are divided into two groups of odd-numbered and even-numbered using the selection signals X and Y, and are alternately driven, that is, ejected.

With this driving method, the ink is ejected from the adjacent nozzle every time one pixel, that is, at most 16 ink droplets are ejected. This is to take into account that when all the nozzles are used continuously when the discharge characteristics are different for each nozzle, a streak or the like occurs in the image. The drive method of alternately discharging as described above suppresses the streak or the like. be able to. In this example, there are two pairs of odd and even numbers.
The nozzle head 17 may be divided into two or more sets.

The level shifter 35 shifts the level of the drive signal, which is the output of the selection gate, up to the power supply voltage required for driving the piezo element. When the output of the level shifter 35 is Hi, a drive signal is output from the driver 36. On the other hand, when the output of the level shifter 35 is in a low state, no drive signal is output.

The driver 36 is supplied with the drive signal waveform from the drive waveform generation circuit 15 described above, and outputs a drive signal according to the drive signal waveform in accordance with Hi / Low from the level shifter 35. I do.

The output terminal of the driver 36a is connected to the head 17
It is connected to the piezo element of each nozzle corresponding to Y.
Here, when a drive signal is given from the driver 36, ink is ejected by the vibration of the piezo element of the connected nozzle. When no drive signal is given, the ink is ejected by the piezo element of the nozzle connected to this terminal. No ejection is performed.

<Description of Operation of Inkjet Printer (Generation of Driving Signal)> FIG. 5 is a timing chart for explaining generation of a driving signal when ink is ejected in all eight gradations.

The 3-bit counter 37 outputs the counter signal C
This is a 3-bit up counter that sequentially increases in response to NT (FIG. 5B) and outputs count signals DC0 to DC2 related to the count signal of the present invention. Reset signal RS
The count value of the 3-bit counter 37 is reset to 0 by T (FIG. 5A).

The ejection signal CMP shown in FIG. 5F is the output of the digital comparator 33. Here, when the value of the image data is equal to or greater than a value obtained by subtracting 1 from the count signal (this is referred to as a count value), the digital comparator 33 outputs the Hi level, and the value of the image data subtracts 1 from the count signal. If the comparison result is less than the output value, a low level is output, and the state of the output is maintained until the comparison result changes.

Here, the waveform of the CMP when the value of the image data is 4, for example, is shown (FIG. 5).
(F)). <Description of operation of switching between driving waveform and heating waveform> Here, referring to the explanatory diagram of FIG. 6, the block diagram of FIG. 7, and the waveform diagram of FIG. 8, a driving waveform used when outputting a driving signal. And a heating waveform used when outputting a heating signal will be described.

First, as the carriage 2 moves, the head moves out of the image forming area (FIG. 6), inside the image forming area (FIG. 6), outside the image forming area (FIG. 6), and carriage return area (FIG. 6). And move repeatedly.

In the image forming area, the ink is discharged as described with reference to FIG. Further, since the area outside the image forming area and the carriage return area correspond to the time of non-printing, the ink is vibrated to generate heat as described later.

As shown in FIG. 7, drive waveform generation circuit 15
Has a heating waveform generator 151 for generating a heating waveform and a drive waveform generator 152 for generating a drive waveform. The drive waveform has a shape as shown in FIG. 8A, and is a waveform for discharging ink by expansion and contraction of the piezo element 17p. Therefore, in order to efficiently eject ink droplets, the frequency of the drive waveform determined by the cycle T1 is set to match the resonance frequency of the head 17. The driving waveform and the AND of the waveform in FIG.
Discharge of ink droplets that express gradation is realized.

A first example of a heating waveform is shown in FIG.
This is a waveform for generating heat by vibrating the piezo element 17p in a state where ink is not ejected, and transmitting this heat to the ink in the head. Therefore,
The period T2 is set so that the frequency is higher than the above-described resonance frequency of the head so that the ink droplets are not ejected. Although the heating waveform from the heating waveform generator 151 has a certain amplitude, a temperature measurement signal from the thermistor 19 in the vicinity of the head 17 (or a detection result from the thermistor 19) is obtained by a gain control described later.
The amplitude is changed from V2 to V3 based on the
It is configured to change.

First, when the carriage is outside the image area or in the carriage return area, the switch 153 and the switch 154 are controlled by the switching control signal from the CPU 11.
Y to 154K are switched to the a side. This allows
The heating waveform having a constant amplitude from the heating waveform generator 151 is supplied to each of the amplifiers 155Y to 155K.

At this time, the gain control circuit 15
7Y to 157K, the first temperature measurement signals th1 to fourth
The temperature measurement signal th4 is applied, and the amplitude of the heating waveform changes according to the head temperature as shown in FIG. 8B. Specifically, the control is performed so that the amplitude of the heating waveform increases when the temperature of the head is low, and decreases when the temperature of the head is high.

In this case, since the amplitude of the heating waveform is proportional to the energy, increasing the amplitude increases the energy for heating. Therefore, by controlling the amplitude of the heating signal, fine temperature adjustment and rapid heating can be performed.

When a heating waveform having such a high frequency is supplied to the piezo element 17p of each head, the head vibrates at a frequency higher than the resonance frequency, so that ink is not ejected and the driving to the piezo element 17p is performed. The current is converted to heat, and the ink near the piezo element 17p is heated, and the temperature rises. Also, a driver IC 1 for generating a drive current
7d also generates heat according to the drive current,
The ink near the driver IC 17d is heated and the temperature rises.

Further, the amplitude of the heating waveform is controlled independently for each head based on the temperature measurement signal from the thermistor 19, so that the temperatures of the YMCK inks are controlled to be equal. As a result, it is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature, while suppressing the structure of the head from becoming complicated.

When the head enters the image forming area, the switch 1 is switched by the switching control signal from the CPU 11.
53 and the switches 154Y to 154K are switched to the b side. Thus, the drive waveform from the drive waveform generator 152 is supplied to each of the amplifiers 155Y to 155K in a fixed gain state, and an image is formed by normal ink ejection.

<Description of Operation for Switching Between Driving Waveform and Heating Waveform> Here, a second example of a heating waveform used when outputting a heating signal will be described with reference to the block diagram of FIG. 9 and the waveform diagram of FIG. This will be described with reference to FIG.

As shown in FIG. 9, drive waveform generation circuit 15
Are the first heating waveform generators 151Y to 151Y which generate the heating waveform.
It has a fourth heating waveform generator 151K and a drive waveform generator 152 for generating a drive waveform.

Here, the second example of the heating waveform is shown in FIG.
(C) is a waveform for generating heat by vibrating the piezo element 17p in a state where ink is not ejected, and transmitting the heat to the ink in the head. Therefore, in order to prevent the ink droplets from being ejected, the period from T3 to T3 is set to be higher than the resonance frequency of the head described above.
T4 is set, or the amplitude is set so that ink is not ejected even within the resonance frequency of the head.

The first heating waveform generator 151Y to the fourth heating waveform generator 151Y
The heating waveform from the heating waveform generator 151K is
The frequency changes based on a temperature measurement signal from a nearby thermistor 19 (or a temperature measurement signal obtained by processing a detection result from the thermistor 19 by the CPU 11).

First, when the carriage is outside the image area or in the carriage return area, the switches 153Y to 153K are turned on by the switching control signal from the CPU 11.
Has been switched to the side. As a result, the heating waveform whose frequency changes at a constant amplitude from the first heating waveform generator 151Y to the fourth heating waveform generator 151K is amplified by the amplifiers 155Y to 155.
5K each.

At this time, the first heating waveform generator 151Y
The first to fourth temperature measurement signals th1 to th4 are applied to the fourth to fourth heating waveform generation units 151K, respectively, and the frequency of the heating waveform changes according to the temperature of the head as shown in FIG. 8C. I do. Specifically, control is performed such that the frequency of the heating waveform increases when the temperature of the head is low, and decreases when the temperature of the head is high.

In this case, since the frequency of the heating waveform is proportional to the energy, increasing the frequency also increases the energy for heating. Therefore, by controlling the frequency of the heating signal, fine temperature adjustment and rapid heating can be performed.

When such a high-frequency heating waveform is supplied to the piezo element 17p of each head, the head oscillates with a voltage lower than the voltage at which ink can be ejected. Is converted into heat, and the ink near the piezo element 17p is heated to increase the temperature. Also, in the driver IC 17d that generates the drive current, heat is generated in accordance with the drive current, so that the ink in the vicinity of the driver IC 17d is heated and the temperature rises.

Further, the frequency of the heating waveform is controlled independently for each head based on the temperature measurement signal from the thermistor 19, so that the temperatures of the YMCK inks are controlled to be equal. As a result, it is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature, while suppressing the structure of the head from becoming complicated.

When the head enters the image forming area, the switch 1 is switched by the switching control signal from the CPU 11.
53 and the switches 154Y to 154K are switched to the b side. As a result, the drive waveform from the drive waveform generator 152 is supplied to each of the amplifiers 155Y to 155K, and an image is formed by normal ink ejection.

<Description of Operation for Switching Between Driving Waveform and Heating Waveform> Here, a third example of a heating waveform used when outputting a heating signal is shown in the block diagram of FIG. 10 and FIG.
This will be described with reference to the waveform diagrams of FIG.

As shown in FIG. 10, drive waveform generating circuit 15
Are the first heating waveform generators 151Y to 151Y which generate the heating waveform.
It has a fourth heating waveform generator 151K and a drive waveform generator 152 for generating a drive waveform.

Here, a third example of the heating waveform is shown in FIG.
(D) is a waveform for generating heat by vibrating the piezo element 17p in a state where ink is not ejected, and transmitting the heat to the ink in the head. Therefore, the period T2 is set so that the frequency is higher than the above-described resonance frequency of the head so that the ink droplets are not ejected.

Although the heating waveform from the heating waveform generator 151 is a continuous pulse, the CPU 11 processes the detection result from the thermistor 19 near the head 17 and generates the first heating time control signals t1 to t4. Heating time control signal t
4, the amount of heating is controlled by switching the ratio of on (passing) / off (blocking) of the switches 154Y to 154K.

First, when the carriage is outside the image area or in the carriage return area, the switch 153 is switched to the side a by the switching control signal from the CPU 11. As a result, a heating waveform having a constant amplitude from the heating waveform generator 151 is supplied to each of the switches 154Y to 154K.

At this time, the first heating time control signal t1 to the fourth heating time control signal t4 are applied to each of the switches 154Y to 154K, and the passage of the heating waveform (a-side state) and the interruption (b-side state) are performed. Switches.

Specifically, the control is performed such that the transmittance of the heating waveform increases when the temperature of the head is low, and decreases when the temperature of the head is high. For example, the CPU 11 performs the heating control by determining how many of the 10 pulses to be passed with 10 pulses of the heating waveform as one basic unit. In FIG. 8D, 1
A state where six of the zero pulses are passed and a state where two pulses are passed are illustrated.

In this case, since the transmittance of the heating waveform is proportional to the energy, the energy for heating increases by increasing the transmittance. Therefore, by controlling the passing rate (passing time) of the heating signal, fine temperature adjustment and rapid heating can be performed.

When such a high-frequency heating waveform is supplied to the piezo element 17p of each head, the head vibrates at a frequency higher than the resonance frequency, so that ink is not ejected and the driving to the piezo element 17p is performed. The current is converted to heat, and the ink near the piezo element 17p is heated, and the temperature rises. Also, a driver IC 1 for generating a drive current
7d also generates heat according to the drive current,
The ink near the driver IC 17d is heated and the temperature rises.

Further, since the amplitude of the heating waveform is controlled independently for each head based on the heating time control signal generated from the temperature measurement signal by the thermistor 19, the temperature of the ink of each color of YMCK is equalized. Is controlled so that As a result, while suppressing the head configuration from becoming complicated,
It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to temperature.

When the head enters the image forming area, the switch 1 is switched by the switching control signal from the CPU 11.
53 is switched to the b side, and switches 154Y to 154K
Is fixed to the a side. Thereby, the drive waveform generator 15
2 is supplied to each of the amplifiers 155Y to 155K to form an image by normal ink ejection.

[Other Embodiments] In the above description, the amplitude control, the frequency control, and the duty control are exemplified for the heating waveform, but any two or three controls can be combined for these. is there. With such a combination, more rapid heating or more subtle heating can be realized.

[Other Embodiments] In the above embodiments, an ink jet printer using four colors of inks of Y, M, C, and K has been described as an example. However, other colors are used. In the case where only a single color is used, or in the case where another number of gradations is used, it is possible to reliably control the ink temperature by the configuration and operation described in each embodiment.

[Other Embodiments] In each of the above embodiments, the heating waveform is applied to the head when the head exists outside the image area or in the carriage return area. Thus, a heating waveform may be applied to a head of a color that does not output image data even in the image forming area. By doing this,
Reliable temperature control can be performed for a color head that is used less frequently.

[Other Embodiments] In addition, FIG.
FIG. 9A is an enlarged waveform diagram illustrating the drive waveform of FIG. It is possible to insert a heating waveform in a period in which the driving waveform is flat and does not contribute to ejection. That is, even when the head is in the image forming area, the heating waveform can be inserted.

In this case, when the frequency of the driving waveform is f, the frequency of the heating waveform is 2f ± 50%.
This is preferable in that heating can be performed without discharging ink. When the amplitude of the driving waveform is V, the amplitude of the heating waveform is 0.
It is preferable to set the voltage to 5 V ± 80% from the viewpoint that heating can be performed without discharging ink.

Further, under the control of the CPU 11, a heating waveform may be applied to a head that does not output image data.

[0144]

As described in detail above, according to the inventions described in this specification, the following effects can be obtained.

(1) According to the invention of the ink jet printer according to the first aspect, the piezoelectric device is heated by the heating signal applied to the piezoelectric device, and the droplets are discharged from the nozzle tip by the heat conduction from the piezoelectric device. The ink in the adjacent liquid storage chamber is heated.

Therefore, since the piezoelectric means for discharging the ink is also used for heating the ink, it is possible to suppress the complication of the structure of the head and to obtain an image due to a change in the ink viscosity due to the temperature. Can be avoided.

(2) In the ink jet printer according to the second aspect of the present invention, the liquid droplets are not ejected from the nozzle tip during non-recording by heat conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means. Heating the ink in the liquid storage chamber adjacent to the piezoelectric means.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and since the heating is performed during non-recording, the temperature of the head is suppressed while the structure of the head is not complicated. It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to the change.

(3) In the ink jet printer according to the third aspect, when the head is located outside the image forming area by heat conduction from the piezoelectric means heated by the heating signal applied to the piezoelectric means, The ink in the liquid storage chamber adjacent to the piezoelectric means is heated without ejecting droplets from the ink.

Therefore, the piezoelectric means for discharging ink is also used for heating the ink, and heating is performed when the head is outside the image forming area, so that the configuration of the head is complicated. It is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature while suppressing this.

(4) In the invention of the ink jet printer according to the fourth aspect, the droplet is not discharged from the nozzle tip by the heat conduction from the piezoelectric means heated by the heating signal whose amplitude changes according to the temperature. Heating the ink in the liquid storage chamber adjacent to the piezoelectric means.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed by the heating signal whose amplitude is controlled. It is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature while suppressing.

In this case, since the amplitude is proportional to the energy, the energy for heating is increased by increasing the amplitude. Therefore, by controlling the amplitude of the heating signal, fine temperature adjustment and rapid heating can be performed.

(5) In the ink jet printer according to the fifth aspect, heat is transmitted from the piezoelectric means heated by the heating signal whose frequency changes in accordance with the temperature, so that the droplet is not discharged from the nozzle tip. Heating the ink in the liquid storage chamber adjacent to the piezoelectric means.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed by the heating signal whose frequency is controlled, so that the structure of the head becomes complicated. It is possible to avoid the adverse effect on the image due to the change in the ink viscosity due to the temperature while suppressing.

In this case, since the frequency is proportional to the energy, increasing the frequency also increases the energy for heating. Therefore, by controlling the frequency of the heating signal, fine temperature adjustment and rapid heating can be performed.

(6) In the invention of the ink jet printer according to the sixth aspect, droplets are discharged from the nozzle tips of a plurality of heads by heat conduction from the piezoelectric means heated by the heating signal selected and applied by the control means. Without discharging
The ink in the liquid storage chamber adjacent to the piezoelectric means is heated.

Therefore, since the piezoelectric means for discharging ink is also used for heating the ink, the structure of each head is suppressed from becoming complicated, and the image due to the change in ink viscosity due to temperature is suppressed. Can be avoided.

(7) In the ink jet printer according to the seventh aspect, droplets are ejected from the nozzle tip by heat conduction from the piezoelectric means heated by a heating signal applied to the piezoelectric means in accordance with image information. Without heating the ink in the liquid storage chamber adjacent to the piezoelectric means.

Therefore, the piezoelectric means for discharging ink can be used for heating the ink, and since the heating is performed when each head is not printed, the structure of the head is prevented from becoming complicated. In addition, it is possible to avoid an adverse effect on an image due to a change in ink viscosity due to temperature.

(8) In the ink jet printer according to the eighth aspect, in accordance with image information representing non-recording, the liquid is discharged from the nozzle tip by heat conduction from the piezoelectric means heated by a heating signal applied to the piezoelectric means. The ink in the liquid storage chamber adjacent to the piezoelectric means is heated without discharging droplets.

Therefore, the piezoelectric means for ejecting ink can be used for heating the ink, and the heating is performed when each head is not recorded based on the non-recorded image information. It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to temperature, while suppressing the configuration from becoming complicated.

(9) In the ink-jet printer according to the ninth aspect, the heat conduction from the piezoelectric means heated by the heating signal selected and applied by the control means causes the head of the nozzle to be moved from the tip of the nozzle when non-recording of each head. The ink in the liquid storage chamber adjacent to the piezoelectric means is heated without discharging the droplet.

In this case, even when one of the heads is recording, the other non-recording head can be heated by vibration. Therefore, the piezoelectric means for ejecting the ink is also used for heating the ink, and since the heating is performed when each head is not printed, the temperature of the head is suppressed while the structure of the head is not complicated. It is possible to avoid an adverse effect on an image due to a change in ink viscosity due to the change.

(10) In the ink jet printer according to the tenth aspect, heat is transmitted from the piezoelectric means heated by the heating signal selected and applied by the control means.
When each head is outside the image forming area, the ink in the liquid storage chamber adjacent to the piezoelectric means is heated without discharging the droplet from the nozzle tip.

Therefore, the piezoelectric means for discharging the ink is also used for heating the ink, and the heating is performed when each head is outside the image forming area. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature, while suppressing the occurrence of a change in ink viscosity.

(11) In the invention of the ink jet printer according to the eleventh aspect, the liquid is discharged from the nozzle tip by the heat conduction from the piezoelectric means which is selected by the control means and heated by the heating signal whose amplitude changes according to the temperature. The ink in the liquid storage chamber adjacent to the piezoelectric means of each head is heated without discharging droplets.

Therefore, the piezoelectric means for discharging ink is also used for heating the ink, and heating is performed by a heating signal whose amplitude is controlled for each head. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature while suppressing complication.

In this case, since the amplitude is proportional to the energy, the energy for heating is increased by increasing the amplitude. Therefore, by controlling the amplitude of the heating signal, it is possible to perform fine temperature adjustment and rapid heating for each head.

(12) In the ink-jet printer according to the twelfth aspect, the liquid flows from the nozzle tip by heat conduction from the piezoelectric means which is selected by the control means and heated by the heating signal whose frequency changes in accordance with the temperature. The ink in the liquid storage chamber adjacent to the piezoelectric means of each head is heated without discharging droplets.

Therefore, the piezoelectric means for discharging ink is also used for heating the ink, and heating is performed by a heating signal whose frequency is controlled for each head. It is possible to avoid adverse effects on an image due to a change in ink viscosity due to temperature while suppressing complication.

In this case, since the frequency is proportional to the energy, increasing the frequency increases the energy for heating. Therefore, by controlling the frequency of the heating signal, it is possible to perform fine temperature adjustment and rapid heating for each head.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram illustrating the overall circuit configuration of an inkjet printer 1. FIG.

FIG. 2 is a block diagram showing a configuration of a head driver in detail.

FIG. 3 is a perspective view showing a state near a head of the ink jet printer.

FIG. 4 is a cross-sectional view illustrating a state near a head of the ink jet printer.

FIG. 5 is a timing chart for explaining generation of a drive signal for performing ejection of all eight gradations.

FIG. 6 is a schematic diagram showing the inside of the image forming area and the outside of the image forming area together with the moving direction of the carriage 2.

FIG. 7 is a block diagram showing a circuit configuration when controlling a heating waveform by temperature.

FIG. 8 is a waveform chart showing an example of a driving waveform and a heating waveform.

FIG. 9 is a block diagram showing a circuit configuration when controlling a heating waveform by temperature.

FIG. 10 is a block diagram showing a circuit configuration when controlling a heating waveform by temperature.

FIG. 11 is a waveform diagram showing an example in which a driving waveform and a heating waveform are combined.

FIG. 12 is an explanatory diagram illustrating the principle of an ink jet printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink-jet printer 2 Carriage 5 Flexible cable 7 Encoder 9 Control board 11 CPU 12 Page memory 13 Line memory 14 Interface 15 Drive waveform generation circuit 16 Head driver 17 Head 17p Piezo element 19 Thermistor 151 Heating waveform generator 152 Drive waveform generator

 ──────────────────────────────────────────────────の Continuing on the front page (72) Kazuo Asano, 1st Sakuracho, Hino-shi, Tokyo Konica Corporation (72) Inventor Junichiro Akune 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation

Claims (12)

[Claims] 1. An ink jet printer which discharges ink droplets from a nozzle tip of a head to record an image, comprising: a drive signal generating means for generating a drive signal for ink discharge based on image information; A piezoelectric means for applying pressure to the liquid storage chamber by a drive signal; a temperature measuring means for measuring the temperature of the head; and a heat generated by vibration in the piezoelectric means based on a measurement result by the temperature measuring means. An ink jet printer comprising: a heating signal generating unit that generates a heating signal for heating ink in the liquid storage chamber. 2. An ink jet printer according to claim 1, wherein said heating signal generating means generates a heating signal during non-printing. 3. The ink jet printer according to claim 1, wherein said heating signal generating means generates a heating signal when the head is located outside the image forming area. 4. The ink-jet apparatus according to claim 1, wherein the heating signal generator controls an amplitude of the heating signal based on a measurement result of the temperature measuring unit. Printer. 5. The ink-jet apparatus according to claim 1, wherein the heating signal generator controls a frequency of the heating signal based on a measurement result of the temperature measuring unit. Printer. 6. An ink jet printer which performs image recording by discharging ink droplets from nozzle tips of a plurality of heads, wherein the driving signal generates a driving signal for ink discharging of each head based on image information. Generating means, piezoelectric means for applying pressure to the liquid storage chamber of each head by the drive signal, temperature measuring means for measuring the temperatures of the plurality of heads, respectively, based on the measurement results of the temperature measuring means, A heating signal generating means for generating a heating signal for heating the ink in the liquid storage chamber by generating heat by vibration by the piezoelectric means of the head; and any one of the drive signal and the heating signal And a control means for selectively applying the control signal to the piezoelectric means. 7. The ink jet printer according to claim 6, wherein said control means selects said heating signal in accordance with said image information and applies the selected signal to said piezoelectric means. 8. The ink jet printer according to claim 7, wherein when the image information is a signal indicating non-recording, the control unit selects the heating signal and applies the selected signal to the piezoelectric unit. . 9. The ink jet printer according to claim 6, wherein said control means selects a heating signal during non-printing and applies the selected signal to said piezoelectric means. 10. An ink jet printer according to claim 6, wherein said control means selects a heating signal and applies the selected signal to said piezoelectric means when the head is outside the image forming area. 11. The heating signal generator according to claim 6, wherein the heating signal generator controls the amplitude of the heating signal for each head based on the measurement result of the temperature measuring means. The inkjet printer according to any one of the above. 12. The heating signal generating means controls the frequency of the heating signal for each head based on the measurement result of the temperature measuring means.
The inkjet printer according to any one of claims 10 to 10.