JP2021024256A - Control method - Google Patents

Abstract

To provide a power supply control circuit capable of preventing a deterioration in image quality while suppressing the cost and size of a power source by performing power supply from an auxiliary power source only in the case of being electric power equal to or more than electric power supplied during normal use of the power source.SOLUTION: A load measurement circuit 306 measures an amount of ink discharged at a time from record data generated by a data generation part 306, and a first switching circuit 308 and a second switching circuit 309 are controlled to charge a second storage battery 305 in the case where the amount is less than a certain fixed value. The first switching circuit 308 and the second switching circuit 309 are controlled to supply electric power charged in the second storage battery 305 as head driving voltage in the case where the amount of ink is the certain fixed value or more. A voltage drop amount in a recording head considering the existence/nonexistence of supply from the second storage battery 305 is predicted, and discharging is stabilized and a deterioration in an image is prevented by transmitting a PWM signal of an optimum heat pulse to a power control circuit.SELECTED DRAWING: Figure 3

Description

The present invention relates to supplying power to a recording head of an inkjet recording device.

The maximum ink ejection current of the recording head in the inkjet recording device is an extremely rare image pattern, and may be a very large current such as a total ejection of four colors of about 50 columns or a total ejection of three colors of about 100 columns. If the power supply is designed according to this current consumption, the power supply will be excessive compared to the capacity during normal use. Further, when power transmission is performed in a non-contact manner, the power transmission efficiency may be lower than in the case where power transmission is performed by wire, so that a power source having a larger capacity is required.

An excessive power supply may increase the power supply cost and increase the size of the power supply, which may affect the product size.

In order to avoid these effects, an auxiliary power supply such as a secondary battery or electric double layer capacitor is installed in the carriage unit (hereinafter referred to as CR unit) on which the recording head is mounted, and the auxiliary power supply is charged when the discharge current is low. When the discharge current is large, the load leveling can be achieved by supplying the discharge current from the auxiliary power supply to the recording head. As a result, the power supply capacity can be made close to that during normal use, and the cost and size of the power supply can be suppressed.

In Patent Document 1, the start of power supply from the capacitor to the load is controlled by comparing the voltage applied to the load and comparing the terminal voltage of the capacitor.

JP-A-2007-130921

However, in the above-mentioned Patent Document 1, since the start of power supply from the capacitor to the load is controlled by the comparison of the voltage applied to the load and the comparison of the terminal voltage of the capacitor, charging / discharging is unique to the power consumption of the load. not decided.

When the load is the recording head of an inkjet recording device, the amount of voltage drop will differ if the load is the same, that is, if the power supply from the auxiliary power supply continues to be discharged near the threshold value, and as a result, the auxiliary power supply There is a difference in the amount of ink ejected depending on whether the power is supplied or not. In the current control method in which the amount of applied power (PWM control of heat pulse) is determined by predicting the amount of voltage drop, inconsistency occurs and the image quality deteriorates.

Therefore, according to the present invention, power is supplied from the auxiliary power supply only when the power exceeds the power supplied during normal use of the power supply, and power that can prevent deterioration of image quality while suppressing the cost and size of the power supply. The purpose is to provide supply control times.

In order to achieve the above object, the power supply control circuit to the recording head according to the present invention is used.
The recording head in the inkjet recording device is supplied with power from the auxiliary power supply in the case of an overloaded discharge condition, and assists in controlling the voltage drop amount to predict the applied power amount (PWM). Different control tables are used with and without power supply from the power source. Since PWM control is possible according to the decrease in the voltage drop when power is supplied from the auxiliary power supply, the applied power amount can be the same regardless of whether the auxiliary power supply is charged or discharged, and ink can be discharged. Since it is stable, it is possible to prevent deterioration of image quality.

According to the power supply control circuit to the recording head according to the present invention, it is possible to prevent quality deterioration of the printed image.

This is the configuration of the carriage in this embodiment. It is a block diagram of the power receiving circuit attached to the conventional carriage. It is a block diagram of the power receiving circuit which mounted the auxiliary power source in this Example. It is a graph which showed the amount of voltage drop. It represents the current control flow. It is a flowchart which shows the control of a heat pulse. This is a table when power is supplied from the auxiliary power supply. Is a table when there is no power supply from the auxiliary power supply.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

The power supply design in the conventional inkjet recording device considers the power that maximizes the discharge amount at one time, such as the extremely rare image pattern of 50 columns for all 4 colors and 100 columns for all 3 colors. It is designed. Therefore, it is an excessive power supply that has an output higher than the power used in the normal state, but if this extremely rare pattern is not taken into consideration, the amount of voltage drop when discharging the maximum amount may exceed a certain value. Problems such as ink not being ejected occur, resulting in deterioration of print quality. If the power supply becomes excessive, the power supply cost will increase and the power supply size will increase, which will have a large effect on the size of the main body of the inkjet recording device.

Furthermore, when power is transmitted to the recording head in an inkjet recording device by non-contact power supply, it is necessary to consider the transmission efficiency of the non-contact power supply, which is an excessive power supply compared to the case where power is supplied by wire. It ends up.

FIG. 1 is a configuration diagram when power transmission to a recording head in a conventional inkjet recording device is non-contact power supply.

A power receiving antenna and an electric circuit 102 are mounted on a carriage 101 on which a recording head is mounted. A power transmission antenna 104 is attached to the rail 103 scanned by the carriage, and the power transmitted from the power transmission antenna 104 is received by the power reception antenna. The power receiving antenna may be one formed by pattern wiring on a substrate or one in which a copper wire is wound in a coil shape. The alternating current received by the power receiving antenna is rectified by the rectifier circuit in the power receiving circuit. After being rectified, a step-up DCDC converter is arranged to convert the voltage into a voltage that drives the recording head. Although the transmission / reception antenna is arranged between the carriage and the rail in FIG. 1, the arrangement of the power transmission antenna and the power reception antenna such as between the upper part of the carriage and the top surface of the printer is not limited to the arrangement described in this embodiment.

FIG. 2 is a block diagram when power is supplied to the carriage in a non-contact manner.

The head power supply is supplied to the power transmission circuit by the CPU controlling the head power supply SW. A power transmission antenna is connected from the power transmission circuit by an electric wire such as an FFC, and power is transmitted from this power transmission antenna to a power receiving antenna and a carriage on which the power receiving circuit is mounted. In this embodiment, the power transmission circuit is configured on the same board as the CPU, but a separate board may be used and connected by an electric wire such as an FFC. The power received by the power receiving antenna is boosted and stabilized by the voltage generation circuit 202 to the drive voltage of the recording head, and drives the recording head 204. The storage battery 203 is an aluminum electrolytic capacitor, and the portion that cannot supplement the drive voltage of the recording head 204 is covered by discharging the electric power charged in the storage battery 203.

As described above, when the head drive power is transmitted by non-contact power supply, the power transmission efficiency of the non-contact power supply system must be taken into consideration. For example, if the power transmission efficiency is 70%, it is necessary to design a power source in consideration of the shortage of 30%. To reduce the power supply, it is possible to increase the capacity of the aluminum electrolytic capacitor of the storage battery 203, but considering the accuracy of power transmission efficiency, the power supply and the aluminum electrolytic capacitor are designed with a margin. , It becomes an excessive power supply system. As a result, the size of the power supply becomes large and the size of the aluminum electrolytic capacitor becomes large, which affects the cost and the size of the device. The specifications are such that the power supply can cover only the power in the normal use state, and by providing an auxiliary power supply for the carriage, when the power is insufficient, such as an image pattern that maximizes the amount of power discharged at one time, from the auxiliary power supply to the recording head Supply power.

FIG. 3 is a block diagram of a head power supply circuit equipped with an auxiliary power supply.

The electric power received by the power receiving circuit 301 is boosted and stabilized by the drive voltage of the recording head in the first voltage generation circuit 302, and drives the recording head 304. The first storage battery 303 is an aluminum electrolytic capacitor similar to a conventional power receiving circuit, and has a capacity sufficient to withstand a normal use state. The second storage battery 305 is an auxiliary power source such as a secondary battery or an electric double layer capacitor, and when the power of the recording head is insufficient, the power charged in the second storage battery is discharged to compensate. The load measurement circuit 307 has a circuit that receives the recording data generated by the data generation unit 306 for the recording head to eject ink from the image data and measures the amount of ink ejected at one time based on the recording data. doing.

The load measurement circuit 307 calculates the amount of ink to be ejected at one time based on the recorded data received from the data generation unit 306, and the calculated measured value and the threshold value for determining the necessity of power supply from the auxiliary power supply. To compare. If the calculated measured value is less than the threshold value, power supply from the second storage battery, which is an auxiliary power source, is not required. Therefore, the load measurement circuit 307 controls the first switching circuit 308 and the second switching circuit 309. The second storage battery 305 is charged through the charging circuit 310. When the amount of ink ejected at one time calculated from the recorded data generated by the data generation circuit 306 is equal to or greater than the threshold value, power supply from the second storage battery is required. Therefore, the load measurement circuit 307 includes the first switching circuit 308 and By controlling the second switching circuit 309 and discharging the electric power charged in the second storage battery 305, it is supplied as the driving electric power of the recording head. The electric power discharged from the second storage battery 305 is boosted and stabilized to the voltage for driving the recording head 304 by the second voltage generation circuit 311 and supplied to the recording head as an auxiliary power source.

However, if the recorded data near the threshold value that determines the necessity of power supply from the auxiliary power supply is continuously discharged, the amount of voltage drop will differ depending on whether or not the power is supplied from the auxiliary power supply despite the same load.

The graph shown in FIG. 4 shows the amount of voltage drop when the discharge is continued near the threshold value of the discharge amount of power supplied from the second storage battery 305.

Graph 401 shows the amount of voltage drop when there is no supply from the second storage battery which is an auxiliary power source, and graph 402 shows the amount of voltage drop when there is power supply from the second storage battery. As shown in this figure, the amount of voltage drop is smaller when there is power supply from the auxiliary power supply than when there is no power supply. For the heat pulse that determines the current applied power amount, the optimum PWM value is selected from the table prepared by predicting the voltage drop amount.

FIG. 5 shows the current control flow.

The load measurement unit calculates the amount of voltage drop from the print data and adjusts the amount of applied power by selecting the optimum heat pulse from the prepared table. Therefore, as described above, if there is a difference in the amount of voltage drop depending on whether or not power is supplied from the auxiliary power supply despite the same load, a heat pulse that originally assumes the amount of voltage drop without power supply from the auxiliary power supply is used. Although it should be input, the power is actually supplied from the auxiliary power supply, and a heat pulse longer than necessary is input. On the contrary, if a heat pulse is selected from the table based on the amount of voltage drop when power is supplied from the auxiliary power supply, a heat pulse shorter than the actual amount of voltage drop is selected. Since an appropriate heat pulse is not selected, the applied power required for ejection becomes excessive or too small, which affects the ejection of ink and deteriorates the print image quality. In order to solve this problem, it is necessary to prepare a separate heat pulse table depending on whether or not power is supplied from the auxiliary power supply.

FIG. 6 is a flowchart showing control of the heat pulse depending on whether or not power is supplied from the auxiliary power supply. From the print data discharged by the load measurement circuit at one time, it is determined whether or not power is supplied from the auxiliary power supply.

FIG. 7 is a table when power is supplied from the auxiliary power supply, and when power is supplied from the auxiliary power supply, a heat pulse is selected from this table.

FIG. 8 is a table when there is no power supply from the auxiliary power supply, and when there is no power supply from the auxiliary power supply, selection is made from this table. By doing so, since the image is driven by an appropriate heat pulse, it is possible to print without deteriorating the image quality regardless of whether or not the power is supplied from the auxiliary power source.

In this embodiment, the load measurement circuit is mounted on the carriage, but it may be configured on the board on which the CPU is mounted, or it may be built in as a function of the ASIC.

101 carriage unit, 102 power receiving antenna,
103 Carriage scanning rail

Claims (2)

A recording device including a recording head for ejecting ink includes a print data generation circuit for the recording head, a power supply control circuit, and a load measurement circuit for the recording head, and the power supply control circuit drives the recording unit. A power receiving circuit that receives the power to be generated, a first voltage generation circuit, a second voltage generation circuit, a power control circuit of the recording head, a first storage battery, a second storage battery, and the second storage battery. The output of the power receiving circuit is connected to the first voltage generation circuit, and the output of the first voltage generation circuit is the charging circuit, the first storage battery, and the power control. Connected to the circuit, the charging circuit generates power to charge the second storage battery, connects to the second storage battery via the first switching circuit, and the output of the second storage battery is the second. The output of the second voltage generation circuit is connected to the power control circuit via the second switching circuit, and the output of the print data generation circuit is connected to the recording head. The load measurement circuit is connected to the load measurement circuit and measures the amount of power required for the recording head to record an image from the image data, and the result of the measurement circuit is a first predetermined value. In the following cases, a first switching signal for switching the first switching circuit to the side for charging the second storage battery is generated, and when the result of the measurement circuit is equal to or greater than the second predetermined value, the second switching circuit is generated. A signal generation circuit that generates a second switching signal that switches the switching circuit from the second storage battery to the side that supplies power to the recording head, and a signal that drives the recording head according to the result of the measurement circuit. A drive signal generation circuit generated by using arithmetic processing is provided, a plurality of arithmetic contents of the arithmetic processing are prepared, and one of a plurality of arithmetics is selected and output according to the first and first switching signals. A power supply control circuit for a recording head and a control method thereof, characterized in that the power control circuit is controlled. The power supply control circuit according to claim 1, wherein the power transmission circuit that transmits power to the power receiving circuit is not in contact with the power transmission circuit.