JPH10226076A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a best print quality by detecting a voltage being applied to a measuring resistor connected with a PTC heater for heating ink, calculating power consumption of the PTC heater based on the applied current, voltage and the rate of conduction time, and controlling the ratio of conduction time thereby controlling the ink temperature accurately. SOLUTION: Ink in an ink container is fed through a pump to an ink heating block where it is heated by a PTC heater 7 before being fed to a nozzle. An operating circuit 22 calculates power consumption of the PTC heater 7 based on a voltage being applied to a measuring resistor 21 connected in series with the PTC heater 7. It is then compared with power consumption of the PTC heater 7 determined by the relationship of power consumption and temperature rise of ink stored at a data storing section 23. If the calculated power consumption is higher, the conduction time rate of voltage being applied to the PTC heater 7 is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an ink jet recording apparatus.

[0002]

2. Description of the Related Art In order to stabilize print quality, there is a combination of a heater for heating ink, a temperature detector for detecting an ambient temperature, and a circuit for controlling the heater. A PTC heater is used as a heater. The heater is controlled by detecting the ambient temperature with a temperature detector, comparing the temperature with the ink temperature at which optimum print quality can be obtained, and determining the amount of ink heating based on the temperature difference ΔT. Japanese Patent Application Laid-Open No. Hei 7-137294 has filed a method in which the input voltage to the heater is intermittently applied based on the temperature and the ratio of the energizing time is controlled.

[0003]

In the above prior art, the ratio of the power supply time to the heater depends on the ambient temperature, and the ratio of the power supply time to the heater stored in advance and the amount of heating to the ink are different. Determined from the relationship. The amount of heat applied to the ink is proportional to the power consumption of the heater. Therefore, when the relationship between the ratio of the power-on time to the heater and the power consumption changes due to variations in the characteristics of individual heaters or changes in characteristics over time. In addition, there is a problem that the ink temperature after heating changes. Also, P
The TC heater has a constant power consumption and a stable characteristic above a temperature (Curie point) at which the resistance value sharply increases. There is a problem that the variation in the relationship with the electric power increases.

As a means for solving these problems, feedback control for detecting the temperature of the heated ink and controlling the amount of heating can be considered. In this case, it is necessary to provide a means for detecting the temperature of the heated ink. is there.

An object of the present invention is to reduce a predetermined power consumption determined by the ambient temperature without being affected by variations in characteristics among individual PTC heaters or changes in characteristics over time, and without using feedback control. In other words, a predetermined heating amount is given to the ink when consumed by the heater.

[0006]

In order to achieve the above object, according to the present invention, a measuring resistor having a resistance value sufficiently smaller than that of a PTC heater is connected in series with a PTC heater for heating ink. The power applied to the PTC heater is calculated based on a voltage applied to the PTC heater by detecting a voltage applied to the measuring resistor, and calculating a power consumption of the PTC heater from a ratio of a current passing through the PTC heater, the applied voltage, and a conduction time. Of the current supply time is controlled.

[0007]

1 and 2 show a schematic block diagram of an ink jet recording apparatus according to one embodiment of the present invention.

The ink holding container 1 is filled with the ink 2, and the ink 1, the supply pump 3, the filter 4, the pressure regulating valve 5, the ink heating block 6, the nozzle 8, and the tubes 11a, 11b, 11c, 11d respectively. And a gutter 9 for collecting the ink particles 13.
The collection pump 12 and the ink holding container 1 are connected by a tube 11e. The ink heating block 6 is installed in the nozzle head 10, and the ink heating block 6 has a built-in PTC heater 7. This PTC
The temperature detector 17 installed in the heater 7 and the nozzle head 10 is connected to a control circuit 16.

The control circuit 16 receives a PTC signal from the constant voltage power supply 18.
A relay switch 1 for turning on and off the power supply to the heater 7
9, changeover switch 20, measuring resistor 21, arithmetic circuit 2
2, a data storage unit 23.

In the data storage unit 23, the ink temperature at which a suitable print quality determined by the ambient temperature is obtained, for example, the relationship between the power consumption of the PTC heater and the temperature increase ΔT of the ink shown in FIG. The relationship between the power-on time ratio and the power consumption shown in the ideal power-on time ratio-power consumption characteristic 24 of the PTC heater is stored.

Ink 2 filled in ink holding container 1
Is pressurized by the supply pump 3, the impurities are removed by the filter 4, the pressure is adjusted to an arbitrary pressure by the pressure regulating valve 5, supplied to the ink heating block 6, and the ink passes through the heating block 6. In the meantime, the mixture is heated to a predetermined temperature by the PTC heater 7 and then supplied to the nozzle 8. The ink 1 is vibrated by the nozzle 8, and after being ejected from the nozzle 8, the ink particles 13 are ejected by the surface tension of the ink 1 and the applied vibration.
Becomes The ink particles 13 are charged by the charging electrode 14 with a charge amount corresponding to the character information, deflected by the deflecting electrode 15, and printed on a printing object (not shown). The ink particles 13 not used for printing enter the gutter 9 and are collected in the ink holding container 1 by the collection pump 12.

As shown in FIG. 3, the PTC heater 7 operates at a predetermined energizing time ratio T1 / T2 based on a temperature difference ΔT between the ambient temperature detected by the temperature detector 17 and the ink temperature at which a suitable print quality is obtained. Can be added.

Here, the characteristics of the PTC heater 7 will be described.

FIG. 4 shows typical temperature-resistance characteristics of the PTC heater 7. When the temperature of the PTC heater 7 exceeds a certain temperature, the resistance value rapidly increases, and the temperature at which the resistance value becomes twice the resistance value at normal temperature is called a switching temperature or a Curie point. Therefore, the PTC heater 7 has a characteristic that the temperature does not rise above a certain temperature located near the Curie point even if the applied voltage or the heat radiation condition changes, and this is called a self-heating suppression effect. The PTC heater 7 is often used for heating an object to be heated to a certain temperature by utilizing the self-heating suppressing effect. However, as shown in the present embodiment, when the heating amount given to the ink 1 to be heated is to be arbitrarily controlled using the PTC heater 7, the temperature is lower than the Curie point at which the self-heating suppression effect acts. It is indispensable to control and use the energization time ratio applied to the PTC heater indicated by T1 / T2. P
The amount of heating that the TC heater 7 gives to the ink 1 is proportional to the power consumed by the PTC heater 7, and FIG. 5 shows a typical example of the relationship between the power-on time ratio indicated by T1 / T2 and the power consumed by the PTC heater 7. Is shown. As shown in the ideal energization time ratio-power consumption characteristic 24 of the PTC heater 7, the energization time ratio is continuously changed from a state where there is no energization time to a state where the energization time ratio is 100% where continuous energization is performed. Then, the power consumption in the PTC heater 7 increases in proportion to the increase in the energization time ratio, but the power consumption becomes constant above a certain energization time ratio. At the inflection point where the power consumption becomes constant, the temperature of the PTC heater 7 rises to near the Curie point.
By controlling the TC heater 7, the amount of heating of the ink 1 can be controlled. However, the PTC heater 7 generally has a variation of about ± 30% in resistance and a change with time at a temperature lower than the Curie point, and the power consumption is reduced even when a voltage is applied at the same energization ratio. Variations will occur. On the other hand, at a temperature equal to or higher than the Curie point, the resistance value sharply increases, and the variation in power consumption among individuals and over time tends to decrease. The range of variation in power consumption due to this energization time ratio is shown in Range 25 of variation in power consumption.

Next, a description will be given of a control operation of the PTC heater 7 according to the present invention, which applies a predetermined heating amount to the ink 1 to be heated without being affected by variations in power consumption of the PTC heater 7.

Normally, the contact of the changeover switch 20 is connected to the A side.

The arithmetic circuit 22 compares the ambient temperature detected by the temperature detector 17 with the ink temperature at which a suitable print quality determined by the ambient temperature stored in the data storage unit 23 is obtained, and raises the temperature of the ink. The temperature ΔT is obtained, and the ΔT is used to calculate the temperature PT from the relationship between the power consumption of the PTC heater stored in the data storage unit 23 and the ink temperature increase temperature ΔT.
The power consumption to be consumed by the C heater 7 is determined, and the power consumption time ratio of the voltage applied to the PTC heater 7 is determined from the power consumption based on the relationship between the power consumption time ratio stored in the data storage unit 23 and the power consumption. The relay switch 19 is turned on and off in accordance with the ratio of the energization time, a voltage is applied to the PTC heater 7, and the ink 1 is heated by the ink heating block 6.

When a certain period of time has passed since the start of energization and the thermal equilibrium state is reached in the ink heating block 6, the changeover switch 20
Is switched to the B side, and the measuring resistor 21
It is connected to the C heater 7 in series. Measuring resistor 2
1 is selected so that the change in resistance value due to temperature, passing current, etc. is small. Further, the resistance value of the measuring resistor 21 is set sufficiently smaller than the resistance value of the PTC heater 7, for example, 1 / (1) of the resistance value of the PTC heater 7 at normal temperature.
It is set to about 50.

The arithmetic circuit 22 calculates the power consumption of the PTC heater 7 from the voltage applied to the measuring resistor 21,
Thereafter, the contact of the changeover switch 20 is switched to the A side. PTC is calculated from the voltage applied to the measuring resistor 21.
A method of calculating the power consumption of the heater 7 will be described using the following mathematical formula.

[0020]

(Equation 1)

[0021]

(Equation 2)

The changeover switch 20 is calculated according to the following equation:
The resistance value R _ptcB of the PTC heater 7 when the contact point is on the B side is determined. Resistance R _s of the measuring resistor 21 at this time PT
Since the resistance value of the C heater 7 is set sufficiently smaller than the resistance value R _ptcB , the PTC when the contact of the changeover switch 20 is on the A side is set.
The resistance R _ptcA of the heater 7 is determined by _setting the contact of the changeover switch 20 to B.
It is assumed that the resistance value is the same as the resistance value R _ptcB of the PTC heater 7 on the side. Next, the power consumption W _A of the PTC heater 7 when the contact point of the changeover switch 20 is on the A side can be obtained by the calculation formula shown in Expression 3.

The arithmetic circuit 22 calculates the power consumption W _A of the PTC heater 7 obtained by the calculation method, the power consumption of the PTC heater 7 stored in the data storage unit 23 and the temperature of ink temperature Δ
The power consumption to be consumed by the PTC heater 7 determined from the relationship of T is compared. As a result of the comparison, when the power consumption obtained by the calculation method is larger, the energization time ratio of the voltage applied to the PTC heater 7 is reduced. When the power consumption obtained by the calculation method is smaller, the voltage applied to the PTC heater 7 is reduced. By increasing the power supply time ratio, the PTC heater 7 can consume predetermined power consumption determined by the ambient temperature.

By performing the above control operation at regular intervals, a predetermined heating amount can be applied to the ink 1 which is the object to be heated, without being affected by variations in the characteristics of the PTC heater 7.

As another embodiment, the same effect can be obtained even if the temperature of the ink 1 before the heating is detected by the temperature detector 17.

[0026]

According to the present invention, it is possible to apply a predetermined heating amount to the ink 1 which is an object to be heated without being affected by variations in the characteristics of the PTC heater 7 and changes in the characteristics over time. In addition, the temperature of the ink 1 ejected from the nozzles 8 can be accurately controlled, and suitable printing quality can be obtained.

Since the temperature of the heated ink 1 can be accurately controlled without using feedback control for detecting the temperature of the heated ink 1 and controlling the amount of heating, the heating of the nozzle head 10 can be performed. There is no need to install a temperature detector for detecting the ink temperature later, and the structure inside the nozzle head 10 can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of a PTC heater drive circuit according to one embodiment of the present invention.

FIG. 2 is a system diagram according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a temperature difference to be heated and a ratio of energization time to a PTC heater.

FIG. 4 is a characteristic diagram showing a relationship between a temperature and a resistance value of a PTC heater.

FIG. 5 is a characteristic diagram showing a relationship between a power supply time ratio to a PTC heater and a power consumption value.

FIG. 6 is a characteristic diagram showing a relationship between a temperature difference to be heated and a required power consumption value.

[Explanation of symbols]

7 PTC heater, 16 Control circuit, 17 Temperature detector, 18 Constant voltage power supply, 19 Relay switch, 20
Changeover switch, 21: measuring resistor, 22: arithmetic circuit,
23 Data storage unit.

Claims (6)

[Claims] 1. A nozzle for ejecting ink particles, a charging electrode for charging the ejected ink particles with a printing signal, a deflecting electrode for deflecting the charged ink particles, and printing of characters and figures. An ink jet recording apparatus comprising: a gutter caught so as to reuse ink particles that have not been supplied to the heater; a heater for heating the ejected ink; and a control unit for changing a heating amount by the heater. A measuring resistor connected in series to calculate a power applied to the heater from a voltage applied to the measuring resistor, and controlling a heating amount of the ink based on a result of the calculation. apparatus. 2. The ink-jet recording apparatus according to claim 1, wherein the measuring resistor is connected in series with the heater only when calculating the electric power applied to the heater. 3. An ink jet recording apparatus according to claim 1, wherein a PTC heater is used as said heater. 4. The ink jet recording apparatus according to claim 1, wherein the amount of heating of the ink is controlled in accordance with a detected value of an ink temperature or an ambient temperature by a temperature detector. 5. The ink jet recording apparatus according to claim 1, wherein the control of the amount of heating of the ink is performed by intermittently applying a voltage to the heater and changing a ratio of a power-on time. 6. The ink-jet recording apparatus according to claim 1, wherein the heating amount of the ink is increased at a low temperature when the viscosity of the ink increases.