JPH03234630A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To provide a highly reliable, compact-designed recording device that is manufacturable at low cost and is capable of producing quality images at high speed by providing a selector circuit that selects pulse durations, each of which is suitable to each of characteristics of recording heads, for a voltage when the voltage being common to all of the recording heads is applied with a voltage source to the recording heads. CONSTITUTION:An output voltage is set invariable, for instance, at 24V with a constant voltage source 11. Discharge ports that are 128 in number are arranged in a row in 200dpi density in ink-jet heads 21, 22, 23 and 24, and ink in colors of cyan, magenta, yellow and black are discharged therefrom, being foamed with thermal resistance elements that are heated with voltage impressed thereto. Pulse durations to be applied to the recording heads 21-24 are set in accordance with characteristics of the ink so that optimum for the discharge can be attained. The pulse durations to be applied to each of the recording heads are stored in drive control circuits 31-34, and selection of the pulse durations to be applied is made out of the stored values. A control circuit 44 controls a selector circuit that selects a drive control circuit suitable to each of the recording heads, while separating a color image signal into four colors, and works on sequential control for the device as a whole.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to an inkjet recording device having functions such as a facsimile machine, a copying machine, or a blinker, and an output device such as a multifunction device or a workstation equipped with such functions. The present invention relates to an inkjet recording device.

[Prior Art] Inkjet recording devices are excellent recording devices that have many advantages, such as low noise, high-speed recording, high image quality, and the ability to obtain color images with high saturation, and have been actively developed in recent years. Among them, color printing devices with a plurality of printheads arranged are attracting attention as they can achieve high speed and high image quality.

[Problems to be Solved by the Invention] However, each recording head has slightly different characteristics for each color, that is, depending on the type of ink, so in order to obtain even higher quality images, it is necessary to have individual power supplies. It is necessary to set the voltage depending on the characteristics of each recording head.

For this reason, there are problems in that the device becomes large and expensive, and also causes a decrease in reliability.

The present invention has been made in view of these points, and it is an object of the present invention to provide an inkjet recording device that is high speed, high image quality, highly reliable, compact, and inexpensive.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides an inkjet recording apparatus including a plurality of inkjet recording heads, which includes a power supply that applies a common voltage to the plurality of recording heads. and a selection circuit that selects a pulse width corresponding to the characteristics of the recording head when applying a voltage from the power source to the recording head.

[Function] According to the present invention, a plurality of inkjet recording heads are provided, a common voltage extracted from a single power source is applied to each head, and a pulse having a width corresponding to the characteristics of each inkjet head is applied. As a result, it is possible to obtain a highly reliable, compact, and inexpensive inkjet recording device.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Husband blood! FIG. 1 shows, as a preferred embodiment of the image forming apparatus of the present invention, an example of the configuration of a so-called bubble jet (BJJ type) color ink jet recording apparatus having an electrothermal converter as an ejection energy generating means.

In FIG. 1, a recording medium 1 such as paper or a plastic sheet is supported by conveyance rollers 2 and 3 consisting of a pair of rollers arranged above and below a recording area, and conveyance rollers 2 and 3 are driven by a sheet feed motor 4. is transported in the direction of arrow A. A guide shaft 5 is provided in front of and parallel to the conveyance rollers 2 and 3. A carriage 6 is reciprocated along this guide shaft 5 in the direction of arrow B by the output of a carriage motor 7 via a wire 8 .

A recording head unit 90, which is a BJ type inkjet head, is mounted on the carriage 6. This recording head unit 90 is for creating a color image, and has four recording head units arranged in the scanning direction corresponding to each color of ink: cyan (C), magenta (M), yellow (Y), and black (BK). recording heads 9, namely 9A, 9
It consists of B, 9C, and 9D. The front surface of each recording head 9, that is, a predetermined distance from the recording medium l (for example, 0.8 mm)
) is provided with a recording section in which a plurality of (for example, 128) ink ejection ports are arranged in a vertical line, and an ejection energy generating element ( (electrothermal converter, etc.) 11 (electrification heating)
Bubbles are generated in the ink, and the pressure generated at this time forms flying ink M12, and recording is performed while making ink dots adhere to the recording medium 1 in a predetermined pattern.

Each recording head 9 is equipped with a circuit board of a drive circuit (driver) 29 for driving as described above.

Separate circuit (CPU) of recording device and RO attached to it
A control unit including M, RAM, etc. is formed on the control board 15, and this control unit receives command signals and data signals (recorded information) from an image reader 14 having, for example, a CCD image sensor, and processes the command signals and data signals (recorded information). Based on this, a driving voltage (
Heat voltage) is applied.

An online/offline switching key 1 is provided on the operation panel 160 attached to the exterior case (not shown) of the recording device.
6A, line feed key 16B, form feed key 16C1, recording mode switching key 160, and other key setting sections, as well as several alarm lamps 16E and power lamp 1.
A display section including a warning lamp such as 6F is provided.

FIG. 2 shows a first embodiment of the invention.

In FIG. 2, 11 is a constant voltage power supply, and here 2
The output voltage was set to 4V. 21.22.23 and 2
4 are inkjet heads, and 2 each are inkjet heads.
128 ejection ports are arranged in a row at a density of 00 dpi. Inkjet head 21.22.23 and 2
4 ejects cyan, magenta, yellow, and black ink, respectively.

The inkjet head used here is based on the principle that a voltage is applied to a heating resistor element, which is an ejection energy generator that generates ejection energy for ejecting ink, to generate heat, foam the ink, and eject the ink. In the case of this head 21, a voltage of 24V is applied with a pulse width of 7.0μ.
The conditions where the voltage was applied at sec were the optimum conditions in terms of characteristics. If the applied energy is too large, the life will be significantly shortened, and if the applied energy is too small, the ink ejection becomes unstable, making it impossible to obtain a stable image. As described above, it is important to drive the inkjet head under optimal conditions or application conditions close to optimal conditions.

As mentioned above, the head 21 applies a voltage of 24V with a pulse width of 7
．． It was driven by applying the voltage for 0 μsec. The head 22 has a pulse width of 6.5 μsec, the head 23 has a pulse width of 6.0 μsec, and the head 24 has a pulse width of 8.0 μsec.
It was driven under conditions of .mu.sec or near thereto.

The pulse widths of the heads 21 to 24 were set to optimally eject ink according to the characteristics of the ink supplied to each head.

In FIG. 2, reference numeral 3 denotes a drive control circuit, which stores pulse widths to be applied to each head, and selects and applies pulse widths according to the stored values. 44 is a control circuit in the form of, for example, a microprocessor, which converts color image signals into CMYBK (cyan, magenta, yellow,
It has a selection circuit that selects and supplies signals to the drive control circuit corresponding to each recording head.
It also performs sequence control of the entire device.

The images obtained in this way were well-balanced and of high quality, and the power supply needed to be smaller than conventional ones. In other words, in the past, the voltage was set for each head, so each of the four independent power supplies had to be equipped with the maximum power consumption of the head, and the total power required was four times the maximum power consumption. .

However, the present invention does not require substantially any adjustment of the output voltage, and does not require four times the power of an independent power supply. The reason for this is that no matter what image is being expressed, all four colors will not be fully printed at the same time (all solids), so depending on the color processing parameters, less than three times the power of an independent power supply is sufficient. That's why.

The K-tane Okuyuki drive pulse is not limited to a single pulse, but may be composed of a plurality of pulses. In this example, the heads 21, 22, 23, and 2 used in Example 1 were used.
4, a and b shown in FIG. 3, respectively.

C9 and d pulse waveforms were given. As shown in FIG. 1, in this embodiment, the pulse width of each of the plurality of pulses was selected and driven for each head corresponding to each color. Note that the numbers shown for each pulse are expressed in units of μsec. The applied voltage at this time was 21V.

Mitatechi 1 Seven heads are mounted on the inkjet recording device, and the first
The head was divided into a set of four heads and a second set of three heads, and each head was driven by providing a power source for each. Figure 4 shows the process diagram. Here, 51 and 52 are power supplies, and heads 61, 62, 6, respectively.
4 and 66 and heads 63, 65 and 67. 57 is a control drive circuit. Here, head 61 is black, heads 62 and 63 are cyan, and head 64 is black.
and 65 eject magenta ink, and heads 66 and 67 eject yellow ink.

Here, in order to improve the tonal expression,
62.64 and 66 and heads 63.65. and 67
The settings are such that the amount of ink ejected is significantly different between the two.

Therefore, since the driving voltage ranges are different, the inkjet heads were divided into two groups of four and three, and two power supplies were used. Electrical a51 applies voltage to heads 61, 62, 64 and 66, and power supply 52 applies voltage to heads 63, 65 and 67. Power supply 51 is 24V, and power supply 52 is 16V. Inkjet head 61, 62.63
．． The pulse width of the voltage applied to 64, 65, 66 and 67 is 7.0.7.5.6.0.6.5°7.
0.6.0. and 7.5 μsec.

(Others) The present invention brings about excellent effects particularly in a bubble jet type recording head and recording apparatus among inkjet recording types.

This is because such a system can achieve higher recording density and higher definition.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in a one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. This pulse-shaped drive signal is described in U.S. Pat. Nos. 4,463,359 and 4,345,262.
Those described in the specification are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the wafer is placed in a bending region. In addition, Japanese Patent Application Laid-Open No. 1989-5 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Application Laid-Open No. 59/1989 which discloses a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
The effects of the present invention are also effective even if the structure is based on the publication No.-138461. In other words, regardless of the form of the printhead, printing can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus.

Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally. In addition, even for serial types, there are recording heads that are fixed to the device body, or replaceable recording heads that are attached to the device body to enable electrical connection with the device body and supply of ink from the device body. The present invention is also effective when using a chip-type recording head or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus, to the present invention, because the effects of the present invention can be further stabilized. Specifically, these include capping means for the recording head, cleaning means, pressure or suction means, preheating means using an electrothermal transducer or another heating element, or a combination thereof; It is also effective to perform a preliminary ejection mode in which ejection is performed separately from printing in order to perform stable printing.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, the inkjet recording apparatus of the present invention may take the form of an image output terminal for information processing equipment such as a computer, a copying apparatus combined with a reader, etc., or a facsimile apparatus having a transmitting/receiving function. It may be something.

[Effects of the Invention] As explained above, in the present invention, since a common power source is used for a plurality of heads, it is possible to obtain a highly reliable, compact, and low-cost inkjet recording device. There is an effect that it can be done.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an inkjet recording apparatus according to the invention, FIG. 2 is a diagram showing a first embodiment of the invention, FIG. 3 is a diagram showing a second embodiment of the invention, and FIG. FIG. 3 is a diagram showing a third embodiment of the present invention. 11... constant voltage power supply, 21, 22.23.24.61.62.63.64.6
5.66, 67... Inkjet head, 31, 32.33.34.57... Drive control circuit, 4
4... Control circuit, 51, 52... Power supply. , 1eI January's first fruit Example 7 I evil Fig. 2 Unexploded B Month's second fruit Chaos I column Σ ho■ Ward Fig. 3

Claims (1)

[Claims] 1) In an inkjet recording apparatus equipped with a plurality of inkjet recording heads, a power supply that applies a common voltage to the plurality of recording heads; and a power supply that applies a common voltage to the recording heads from the power supply; An inkjet recording apparatus comprising: a selection circuit that selects drive pulses each having a pulse width that corresponds to the characteristics of a recording head. 2) The recording head is characterized in that the thermal energy generated by the electrothermal converter causes film boiling in the ink, and as bubbles grow due to the film boiling, ink droplets are ejected from the ejection ports. The inkjet recording device according to claim 1. 3) The inkjet recording apparatus according to claim 1, wherein different inks are supplied to each of the plurality of inkjet heads. 4) The inkjet recording apparatus according to claim 1, wherein the drive pulse is composed of a plurality of divided pulses. 5) The inkjet recording apparatus according to claim 1, wherein the plurality of inkjet heads have a plurality of sets of I/J heads to which different inks are supplied, and the power supply is provided for each set. .