JPH0624864B2 - Inkjet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a head drive voltage adjusting means in an inkjet recording apparatus including a bubble jet recording head.

[Prior art]

2. Description of the Related Art An inkjet recording device having a bubble jet recording head is used as a type of recording device such as a printer or a facsimile.

In this type of ink jet recording apparatus, an electrothermal energy converter such as a heating resistor is provided in each of a plurality of ink ejection openings (print dot forming means) provided in the recording head,
A voltage (head drive voltage) is applied to the electrothermal energy converter based on the print data, and the expansive force of the bubble (bubble) grown in the ink ejection port forms a flying ink droplet, which is then recorded on the recording medium. It is configured to be attached and recorded in a predetermined pattern.

In this type of inkjet recording device, bubble growth or the ink ejection amount and ejection speed may change depending on the head drive voltage, which may change the print dot diameter or cause an ink ejection failure, resulting in stable ink ejection and print quality. In order to ensure the above, it is necessary to apply an appropriate head drive voltage (ink ejection voltage).

On the other hand, in the individual print heads, the driving voltage for obtaining stable ink ejection varies due to variations in manufacturing such as variations in the ink ejection ports or years of use, and the ink ejection voltage varies for each recording head. May be different.

However, in the conventional ink jet recording apparatus, since the head drive voltage is adjusted by the power supply circuit, the drive voltage must be adjusted for each print head every time the print head is assembled or replaced. There was a problem that it took a lot of trouble to service and maintain.

In particular, the voltage adjustment is extremely complicated in the case of having a plurality of recording heads for color printing.

Further, there is a possibility that an excessive voltage may be applied due to erroneous adjustment and the recording head may be damaged.

〔Purpose〕

An object of the present invention is to solve such a problem of the prior art, and it is not necessary to adjust the drive voltage one by one when mounting or replacing the recording head, and it is possible to easily obtain a proper proper ink ejection voltage for each recording head. A bubble jet type ink jet recording apparatus is provided.

〔Overview〕

The ink jet recording apparatus of the present invention is provided with a recording head having a plurality of electrothermal energy converters, and a driving voltage for the plurality of electrothermal energy converters is provided to the recording head, and an ink ejection voltage specific to the recording heads. Setting means for setting as electrical binary data for adjustment in accordance with the above, and by being electrically connected to the setting means, the binary data set in the setting means is converted into an adjustment voltage, A constant voltage power supply circuit for adjusting and outputting a drive voltage to the recording head according to the adjustment voltage, and for performing feedback control by comparing a reference voltage and a feedback voltage according to the drive voltage output. With the configuration provided, the above object is achieved.

〔Example〕

 The present invention will be specifically described below with reference to the drawings.

FIG. 1 shows a main part of an inkjet recording apparatus suitable for implementing the present invention.

In FIG. 1, a recording medium 1 such as a sheet of paper or a plastic sheet is supported by conveying rollers 2 and 3 composed of a pair of rollers arranged above and below, and is conveyed in the direction of arrow A. Guide shafts 4 and 4 are provided in front of the conveying rollers 2 and 3 in parallel with them, and a carriage 5 is reciprocally driven in the direction of arrow B along the guide shafts.

A valve jet recording head 6 is mounted on the carriage 5.

On the front surface of the recording head 6, that is, the surface facing the recording medium 1 with a predetermined gap (for example, 0.8 mm), a plurality of (for example, 24 or 32) ink ejection ports 10 (second
Figure) has been formed.

FIG. 2 schematically shows a partial cross section of the ink discharge port 10.

In FIG. 2, each ink ejection port 10 is provided with an electrothermal energy converter 11 composed of a heating resistor or the like, and these electrothermal energy converters are driven based on a print data signal (a head drive voltage is applied). By doing so, the ink 12 in the ink ejection port is heated and the bubble (bubble) 13 grows, and the expansive force of the bubble forms a flying ink drop 14, which is attached to the recording medium 1 to form a print dot. Is formed.

FIG. 3 is a block diagram of the main configuration of the inkjet recording apparatus according to the present invention.

In FIG. 3, a CPU (microprocessor) 20 of the recording apparatus controls motors 22 such as a carriage motor and a conveyance motor via a motor driver 21 and controls a recording head 6 (a head unit including a heat mink). Ink ejection from the ink ejection port 10 is controlled via the mounted head controller 23 and head driver 24.

The CPU 20 is operated by the panel switch 25.

A power supply circuit 26 for driving the head is connected to the head controller 23, and the drive voltage thereof is applied to the electrothermal energy converter 11 (FIG. 2) of a predetermined ink ejection port 10 based on a print data signal. .

FIG. 4 shows a circuit configuration of the power supply circuit 26.

In FIG. 4, the power supply circuit 26 connects the output terminal of the operational amplifier 28 to the base of the transistor 27, connects the collector of the transistor to the power supply V (IN), and supplies the reference voltage V to the negative input terminal of the operational amplifier.
(R) is applied to connect the positive side input terminal of the operational amplifier 28 to the resistor R on the emitter side of the transistor 27.
The voltage dividing point of (1) and R (2) is composed of a constant voltage circuit connected as shown in the figure.

The head drive voltage V (H) is taken out as the output of this constant voltage circuit, that is, the output voltage on the emitter side of the transistor 27.

However, the recording head 6 is provided with the binary data means 29 for voltage setting as shown in FIGS. 3 and 4, and this binary data means is connected to the D / A converter 30 provided in the power supply section. Has been done.

The D / A converter 30 is connected so as to adjust the reference voltage V (R) of the power supply circuit 26 with binary data (bit signal) for voltage setting, and the reference voltage V (R) is changed to change the power supply. The output of the circuit 26 (head drive voltage V (H)) is adjusted.

In the illustrated example, the voltage setting binary data means 29 is composed of a 3-bit DIP switch provided in the recording head 6, and a bit signal corresponding to an ink ejection voltage specific to the recording head is formed by turning it on and off. .

The reference voltage V (R) is the sum of the fixed voltage V (RO) set in the power supply circuit 26 and the output (correction voltage) v (R) of the D / A converter 30, and this correction voltage v (R ) With the bit signal, the reference voltage V
By changing (R), the head drive voltage V (H) is adjusted to the ink ejection voltage specific to the recording head 6.

According to the circuit configuration of FIG. 4, the head drive voltage V (H) can be expressed by the following equation.

That is, a feedback voltage obtained by dividing the output (driving voltage) of the transistor 27. Is compared with the reference voltage V (R) by the operational amplifier 28, and V (H) is controlled so that both are equal. Therefore, V (H) is adjusted by changing V (R) or v (R) by a bit signal, and
Feedback control is performed so that (H) is always equal to the right side of expression (1), so the drive voltage output is stable.

According to the configuration described above, the voltage (head drive voltage) applied to each print head can be set in advance according to the variation of the print head 6 (particularly, the ink ejection ports 10). It is no longer necessary to adjust the ink discharge voltage when installing or replacing, and it has become possible to greatly reduce the time required for service and maintenance.

In particular, in an ink jet recording apparatus having a plurality of recording heads for color printing, the effect of reducing the service and maintenance is great.

Further, damage to the recording head 6 due to erroneous adjustment of the ink ejection voltage could be eliminated.

Further, in the case of a recording head having a large drive capacity such as a plurality of heads, the generated noise also becomes large. However, the above-described configuration has a large noise margin and can effectively reduce the generated noise.

The present invention relates to an inkjet recording apparatus equipped with a plurality of bubble jet recording heads such as color printing, and a line printer method for recording one line at a time or a page printing method for recording one page instead of carriage scanning. The same can be applied to a recording device and the like.

〔effect〕

As is clear from the above description, according to the ink jet recording apparatus of the present invention, a recording head having a plurality of electrothermal energy converters, and a driving voltage to the plurality of electrothermal energy converters provided in the recording head. Is set as electrical binary data for adjusting in accordance with the ink ejection voltage peculiar to the recording head, and is set in the setting means by being electrically connected to the setting means. The binary data is converted into an adjustment voltage, the drive voltage to the recording head is adjusted and output according to the adjustment voltage, and a reference voltage and a feedback voltage according to the drive voltage output are compared. Since the constant voltage power supply circuit for feedback control is provided, it is not necessary to adjust the ink ejection voltage when mounting or replacing the recording head, and erroneous adjustment can be performed. Without damage of the recording head, the service and maintenance easy bubble jet type ink jet recording apparatus of the recording head is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part of an inkjet recording apparatus suitable for carrying out the present invention, FIG. 2 is a schematic sectional view of an ink ejection port of the recording head of FIG. 1, and FIG. FIG. 4 is a block diagram showing the configuration of the inkjet recording apparatus according to the embodiment, and FIG. 4 is a power supply circuit diagram of the recording head shown in FIG. 6 ... Recording head, 10 ... Ink ejection port, 26 ... Power supply circuit, 29 ... Binary data means for voltage setting, 30 ...
D / A converter, V (R) ... reference voltage, V (H) ... head drive voltage.

Claims (2)

[Claims] 1. A recording head having a plurality of electrothermal energy converters, and a drive voltage provided to the recording heads, the drive voltage for the plurality of electrothermal energy converters corresponding to an ink ejection voltage specific to the recording heads. Setting means for setting as electric binary data for adjustment by adjusting, and by being electrically connected to the setting means, the binary data set in the setting means is converted into an adjustment voltage, and the recording head is provided. A constant voltage power supply circuit for adjusting and outputting a drive voltage to the control voltage according to the adjustment voltage and performing feedback control by comparing a reference voltage with a feedback voltage according to the drive voltage output. An inkjet recording device characterized by the above. 2. The constant voltage power supply circuit adjusts and outputs a drive voltage to the recording head by changing the reference voltage according to the adjustment voltage. The inkjet recording device described.