JP2003305843A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve printing quality by reducing a time delay due to an inductance of a flexible flat cable. <P>SOLUTION: In this inkjet recorder equipped with a plurality of flexible flat cables having different lengths, each being provided to transmit an electric driving signal from a driving signal generating circuit to a recording head, values of L/R are normalized to be a predetermined identical value with the proviso that the inductance of the flat cable is represented by L and the resistance is by R. A desired electric driving signal shown by the graph at the bottom in figure which is as much as close to a signal of a driving signal generator shown by the graph at the top in figure is supplied to a piezoelectric element in order to respond to increase or decrease of a current in a short time by suppressing the overshoot. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus equipped with an ink jet recording head that pressurizes a pressure generating chamber by pressure generating means to eject ink droplets from nozzle openings.
More specifically, the present invention relates to a structure of a flexible flat cable that transmits a drive signal to a drive target such as a recording head and a structure of an actuator drive circuit that generates a drive electric signal.

[0002]

2. Description of the Related Art An outline of a conventional recording head drive system in an ink jet serial printer system will be described with reference to the drawings.

FIG. 1 is a diagram showing a relationship between a printer main body (hereinafter referred to as a main body) 1 for performing information processing and supplying drive power to a recording head, and a recording head section 2 to be controlled. The main body 1 is a control circuit 3 for creating data and timing for determining nozzles that eject ink drops.
And a drive signal generation circuit 4 for generating a drive signal for driving the actuator of the recording head 2, transistors 5 and 6 for amplifying the drive signal generated thereby, control data and drive power for the recording head unit 2. Consists of a connector 7 for outputting. The recording head unit 2, a connector 8 for inputting a drive signal from the drive signal generating circuit 4, a plurality of actuators 9 to 11 composed of piezoelectric vibrators that generate kinetic energy for ejecting ink droplets, The analog switches 12 to 14 for controlling the application of the drive signal from the actuator main body and the ON / OFF control of the analog switches 12 to 14 for controlling the vibration of the actuator according to the data from the control circuit 3 in the main body. Control circuit
It consists of 15. The recording head unit 2 reciprocates on a guide in the printer mechanism, and data corresponding to the position on the guide is sent from the main body 1, whereby ink droplets are ejected and printing is performed. The main body 1 and the recording head unit 2 are connected by a flexible flat cable (hereinafter, FFC) 16. The FFC 16 has a strip shape in which a large number of conductive lines 17 are arranged in parallel, so as not to hinder the reciprocating movement of the recording head 2.
It is molded in a synthetic resin 18 that is highly flexible and durable against curved deformation. The conductive pattern 17 itself is also the above synthetic resin 18
In order to maintain the same durability as in (3), a thin plate material made of a copper alloy is patterned into a thin strip shape.

The conductive pattern 17 is composed of a drive signal line, a ground line, a temperature detection signal line, and other drive power source lines of the piezoelectric vibrator, which are determined by the number of kinds of ink. Recently, there is a demand for improvement of print quality. Therefore, in order to diversify the ink types and adapt to the environment such as temperature and humidity of the place where the recording device is installed, the number of types of signals input from the drive signal generation circuit 4 to the recording head 2 must be increased. ing.

Further, due to the expansion of the use of the ink jet type recording apparatus, not only the conventional consumer machine (A4 size) but also the recording head 2 and the ink jet type recording apparatus compatible with the A0 / B0 size large format machine (LFP) will be provided. It has been commercialized, and the length of FFC16 has also been lengthened.

[0006]

The FFC 16 has a length approximately twice the span of movement of the recording head 2 so as not to hinder the smooth reciprocating movement of the recording head 2. There is a proportional parasitic impedance component. Here, of course, in the LFP, the width of the recording head 2 in the main scanning direction increases, so that the length of the FFC 16 is about 4 m.
And the impedance component increases. Figure 2 shows a schematic representation of this. Here, 19 is a variable capacitance simulating 12 to 14 and 9 to 11 in FIG. 1, and 20 and 2
1 is a parasitic inductance component, and 48 and 49 are parasitic resistance components, each of which exists in the conductive pattern 17 of FIG. This inductance component produces a counter electromotive force that is proportional to the time derivative of the current flowing through the FFC 16, but when the amount of current itself increases, the time derivative of the current also increases,
As the capacitive load increases, the back electromotive force increases. As a result, when the length of the FFC 16 is increased, a driving signal near the emitters of the transistors 5 and 6 of the main body 1 and a driving signal between both ends of the variable capacitor 19 are different as shown in FIG. Therefore, there arises a problem that an appropriate drive voltage is not applied to the piezoelectric vibrator. In particular, the inductance component causes overshoot and undershoot of the voltage of the recording head unit 2, and a driving voltage that is substantially higher than an appropriate voltage for driving the piezoelectric vibrator is applied. The ejected ink amount becomes larger than an appropriate value. This means that the position and size of the dots formed by ejection on the paper surface differ depending on the number of nozzles ejected in one pulse, which adversely affects the print quality.

On the other hand, as shown in FIG. 3B, the resistance component of the FFC 16 causes a voltage drop and a response delay when charging and discharging the piezoelectric vibrator. When the current flowing through the FFC 16 becomes large, the voltage on the variable capacitance 19 side drops, and contrary to the inductance component, the piezoelectric vibrator is driven at a voltage that is substantially lower than the appropriate driving voltage. Make the amount smaller than the proper value. Also,
When printing with high print quality corresponding to photo quality,
It is necessary to reduce the amount of ink per dot to about 5 ng, and in order to eject such small ink droplets, the displacement of the piezoelectric vibrator should be made faster than when ejecting large ink droplets (10 to 40 ng) in the past. Driving is an essential requirement. In order to speed up the displacement of the piezoelectric vibrator, it is necessary to shorten the charge / discharge time of the drive signal, which inevitably increases the time rate of change and the absolute value of the current, which causes distortion due to the impedance component of the FFC16. Will increase. In order to solve such a problem, it is necessary to make the impedance component of the FFC 16 as small as possible, but there is a limit to the reduction of the impedance component because it is restricted by the width and length of the FFC 16.

The present invention has been made in view of the above problems, and maintains a high print quality by defining the relationship between the inductance component L and the resistance component R of the conductive pattern 17 of the FFC 16 at a constant value. However, it is still another object of the present invention to provide an ink jet recording apparatus that can use a recording head having the same structure as that of a consumer machine and the same drive signal waveform for LFPs having different FFC16 lengths.

[0009]

To solve the above problems, the present invention provides a first device for generating a drive signal, that is, a drive signal generation circuit, and a second device for ejecting ink according to the drive signal, that is, recording. In the connection of the head part, the inductance component parasitic on the conductive pattern of the FFC that electrically connects the drive signal is effectively reduced, and L / R is set to a constant value in the relationship between the inductance component L and the resistance component R, FF without improving the drive signal waveform
It has become possible to use the recording head for consumer machines and the drive signal waveform used for it in LFPs with different C lengths.

[0010]

[Function] In a plurality of ink jet type recording devices having different FFC lengths, since the inductance component L and the resistance component R of the conductive pattern of the FFC are the same, it is possible to cope with the increase and decrease of the current in a short time. A drive signal with less distortion due to shoot, undershoot, and voltage drop is applied to the piezoelectric vibrator.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

4 and 5 show an example of a schematic structure of an ink jet type recording apparatus. The flow path unit 22 includes a nozzle plate 24 in which nozzle openings 23 are formed at a constant pitch, a pressure generating chamber 25 that communicates with the nozzle openings 23, and a reservoir 27 that supplies ink to the pressure generating chambers 25 through the ink supply ports 26. The formation substrate 28 and an elastic plate 31 for expanding and contracting the volume of the pressure generating chamber 4 by contacting the tips of the piezoelectric vibrators 30 in the longitudinal vibration mode of the piezoelectric vibration unit 29 are integrally laminated. The piezoelectric vibration unit 29 is connected to a cable 32 that transmits a drive signal from the outside, and then housed and fixed in a housing chamber 33, and the flow path unit 22 includes a holder 34 formed by injection molding of a polymer material or the like. The recording head 2 is configured by inserting a frame 35 fixed to the opening surface and also serving as a shield material on the nozzle plate side. In this embodiment, the piezoelectric vibrator 30 in the vibrator mode constituting the piezoelectric vibration unit 29 has an internal electrode 36 serving as one pole and an internal electrode 37 serving as the other pole laminated in a sandwich form with the piezoelectric material 38 interposed therebetween. Then, one of the internal electrodes 36 is exposed to the front end side, and the other internal electrode 37 is exposed to the rear end side, and the segment electrode 38 and the common electrode 39 on each end face are connected to form a piezoelectric constant d31. There is. Then, as shown in FIG. 6, the piezoelectric vibrating unit 29 is fixed by being fixed to the fixed substrate 40 in conformity with the arrangement pitch of the pressure generating chambers. Further, in this embodiment, the piezoelectric vibrator 30 is configured such that one piezoelectric vibration plate is divided into comb teeth so that the rear end side is continuous, and the common electrode 39 of each piezoelectric vibrator is a continuous body. Has been formed. Connector 7 of recording head 39 of FIG. 1 and connector of drive signal generation circuit 4
8 and FFC16 are connected to each other, and a drive signal is transmitted through the FFC16 and sent to the recording head 2 to expand and contract the piezoelectric vibrator 30 to eject ink droplets onto the surface of the recording medium.

In this embodiment, when a trapezoidal drive signal as shown in FIG. 7A is output from the drive signal generation circuit, the semiconductor integrated circuit drives the piezoelectric vibrator 30 which should eject ink droplets. A signal is applied. The piezoelectric transducer 30 is contracted by the rising portion of the drive signal to generate the pressure generating chamber.
25 is expanded, and the pressure generation chamber 25 is passed through the ink supply port 26.
Ink is supplied to. After the flat portion that holds the expanded state of the pressure generating chamber 25 holds it for a predetermined period of time, when the piezoelectric vibrator 30 is discharged by the falling portion, the piezoelectric vibrator 30 expands and returns to the original state, and the pressure generating chamber 25 is contracted, and an ink droplet is ejected from the nozzle opening 23. In the driving method of controlling the ink amount of the ink droplet by positively utilizing the movement phase of the meniscus generated by the expansion of the pressure generating chamber 25 due to the rising portion of the driving signal, such a flat portion of the driving electric signal is used. The time T is manipulated, and particularly when ejecting an ink droplet having an ink amount of about 5 ng, which is suitable for graphic printing, the time T is extremely short, for example, set to about 2 μsec. In such a situation, the capacitance of the piezoelectric vibrator 30 and the transmission path of the drive signal, in this embodiment, the inductance component of the conductive pattern 17 as shown in FIG. 8 increases the rate of change of rising and falling of the current. It depends. That is, when the drive signal is applied, the counter electromotive force ΔE1 due to the inductance component is generated at the beginning of the rising portion as shown in FIG. 7B, and apparently after a lapse of time ΔT1 from the rising portion of the driving electric signal. The electric current begins to flow. When the ratio of the inductance component and resistance of the conductive pattern 17 is not adjusted to an appropriate value and the inductance component is relatively large, the inductance at the end of the rising portion is increased as shown in Fig. 7 (b). Overshoot occurs due to the electromotive force ΔE2 due to the component. This tendency is remarkable when the current flowing through the FFC 16 is large, that is, when the number of piezoelectric vibrators 30 that are driven at the same time is large. Therefore, piezoelectric vibrations that are driven simultaneously, such as a solid image (an image with a large ink ejection amount), etc. When the number of the child 30 is large, the ejection speed of the ink droplets and the ink amount forming the ink droplets increase,
Flight bends and dot dropouts are more likely to occur. These phenomena also occur at the trailing edge of the drive signal, and in particular, in order to eject minute ink droplets,
When the time T of the flat portion is shortened, the waveform falls at a stretch from the overshoot portion to the undershoot portion, the relative distortion of the drive signal increases, and the ejection characteristics of the ink droplets change significantly. Here, the dotted line is the piezoelectric vibrator
The drive signal waveform required to drive 30 is shown, and the solid line shows the drive signal waveform actually input to the piezoelectric vibrator 30.

Therefore, in this embodiment, as will be described later, the ratio of the inductance L and the resistance R of the FFC 16 between the recording head 2 and the drive signal generating circuit 4 of the ink jet recording apparatus is set to a constant value, so that the length of the FFC 16 becomes longer. Even if the length is increased, the resistance R can suppress the overshoot caused by the inductance component L without excessively attenuating the drive signal. That is, as shown in FIG. 7 (c), although a slight attenuation occurs due to the resistance R, the counter electromotive force at the rising end that is caused by the inductance component is damped by the resistance R, and the piezoelectric vibrator 30 is driven at the same time. Regardless of the number, a drive signal close to the drive signal waveform of the drive signal generation circuit 4 can be supplied to the piezoelectric vibrator 30, and therefore the displacement amount and displacement speed of the piezoelectric vibrator 30 can be maintained substantially constant, and printing with high print quality can be performed. be able to.

As shown in FIG. 8, the FFC 16 for transmitting the drive signal from the drive signal generating circuit to the recording head 2 is the first FFC 16
It has a laminated structure of A and the second FFC16B. This FFC16
Is a strip-shaped form in which a large number of conductive lines 17 are arranged in parallel, and is molded in a synthetic resin 18 which is highly flexible and has durability against bending deformation. In order that the conductive pattern 17 itself has the same durability as the synthetic resin 18, a thin plate material made of a copper alloy is patterned into a thin strip shape, and its thickness is 30 to 100 μm.

In FIG. 8, the hatched conductive pattern 17 is the positive electrode side conductive pattern 17A, and the white conductive pattern is the negative electrode side conductive pattern 17B. 1 positive side conductive pattern (COM A) and 2 negative side conductive patterns (GND A)
Is a set of piezoelectric vibrators of one ink color type (here, A
A drive signal of the color type of the column) is transmitted to the recording head 2, and the conductive patterns 16 of each set are regularly arranged in a permutation. Figure
As shown in 8, if there are 6 pairs (columns A to F),
A total of six colors of ink will be ejected corresponding to the six rows of piezoelectric vibrators 30. The six basic rows of ink are black, cyan, magenta, yellow, light cyan, and light magenta as the most basic configuration.

In addition to the drive signal line for the piezoelectric vibrator 30, the FFC 16 is provided with a ground line, a temperature detection signal line, and other drive power supply lines.

Since the conductor wire of the FFC 16 having a laminated structure is very thin, the resistance R per unit area flowing through the conductor wire becomes very large, and the ratio of the inductance component L and the resistance R becomes small. . In addition, the positive electrode side conductive pattern 1
Since there is only one 7A, the amount of current flowing through this conductor is large, and the inductance component L is large, which causes overshoot and undershoot in the drive signal applied to the piezoelectric vibrator, and the drive signal that is required The phenomenon that the waveform is not input to the piezoelectric vibrator 30 occurs.

Therefore, in the present invention, as shown in FIG. 9 (a), by increasing the thickness t of the conducting wire of the FFC 16, the amount of current flowing per unit area is decreased to adjust the resistance component R and the inductance component L. It is possible to adjust the balance between and, and suppress the distortion of the drive signal input to the recording head 2. Also,
As shown in FIG. 9 (b), the number of currents flowing per conductor is reduced by using two positive electrode side conductive patterns 17A, thereby reducing the inductance component L and the resistance component R.
It is possible to suppress the distortion of the drive signal input to the recording head by adjusting the balance between

Next, as a second embodiment, an impedance adjusting element 41 is installed on the drive signal generating circuit as shown in FIG. 10, and the resistance component R and the inductance component L are adjusted to obtain L and R. You can match the relationship.

In this embodiment, the impedance adjusting element is, for example, resistance elements 45 to 47 as shown in FIG.
By installing, the resistance R can be adjusted by the length of the FFC16, and the relationship between L and R can be matched. This resistance element is a relay board between the drive signal generating circuit 4 and the recording head 2.
42 (Fig. 11 (a)) or drive signal generator 4 (Fig. 11
(B)) and the effect can be obtained even if it is installed on the circuit of the recording head 2 (FIG. 11C).

Further, as shown in FIGS. 12A, 12B, and 12C, this impedance adjusting element is composed of coil elements 50 to 52.
However, the same effect can be obtained.

Further, by applying the above-described embodiments in combination, the relationship between the inductance component L and the resistance R can be finely changed, and the effect can be obtained by incorporating existing components without developing new components. Obtainable.

[0024]

As described above, in the present invention, the recording head provided with the piezoelectric vibrator for expanding and contracting the pressure generating chamber communicating with the nozzle opening for ejecting ink droplets, and the piezoelectric vibrator are displaced. Drive signal generating means for generating a drive signal, a switching means for selectively applying the drive signal to the piezoelectric vibrator corresponding to print data, and an FFC for transmitting the drive signal to the piezoelectric vibrator. In a plurality of ink jet recording apparatus provided with, the inductance component between the recording heads from the drive signal generating circuit formed in the FFC that transmits the driving signal to the recording head is L (μH), and the resistance component is R (Ω). When these ratios L / R
Since it is set to be almost the same, it is possible to suppress overshoot as much as possible and respond to the increase and decrease of the current in a short time, and apply a desired drive signal with less distortion to the piezoelectric vibrator to drive it. It is possible to prevent deterioration of print quality due to signal distortion.

As a result, the drive signal waveform designed for the consumer machine can be diverted to the large format printer in which the FFC lengthens and the inductance component increases, and the existing parts can be used, and the low component can be used. By improving the device at cost, it is possible to suppress the design and development of new parts, which leads to cost reduction and development time reduction of the inkjet recording device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a printer system representing an embodiment of a conventional technique.

FIG. 2 is an explanatory diagram in which the configuration of FIG. 1 is simplified.

3A and 3B are diagrams showing drive electric signals of the main body and the recording head in the configuration of FIG. 1, where FIG. 3A shows the influence of the inductance component and FIG. 3B shows the influence of the resistance component.

FIG. 4 is an assembled perspective view showing an embodiment of the recording head of the present invention.

FIG. 5 is a diagram showing a cross-sectional structure at a segment electrode of the same recording head as above.

FIG. 6 is a diagram showing an example of a vibrator unit.

FIG. 7A shows a drive electric signal of a drive signal generation circuit,
The figure (b) shows the drive electric signal applied to the piezoelectric vibrator by the conventional flexible flat cable.
(C) is a diagram showing a drive electric signal applied to the piezoelectric vibrator according to the present invention.

FIG. 8 is a cross-sectional view showing an example of a conventional flexible flat cable.

9A and 9B are views showing a cross-sectional structure of a flexible flat cable according to the present invention, in which FIG. 9A shows the thickness of the conductive pattern, and FIG. 9B shows the state in which the number of cores of the positive electrode side conductive pattern is changed. It is a figure.

FIG. 10 is a schematic view showing an embodiment in which an impedance adjusting element is installed on the drive signal generating circuit according to the present invention.

FIG. 11 is a view in which a resistance element according to the present invention is installed,
FIG. 4A shows an embodiment installed on the relay substrate, FIG. 2B shows an embodiment installed on the drive signal generating substrate, and FIG.

12A and 12B are diagrams in which the coil element according to the present invention is installed. FIG. 12A is installed on the relay substrate, FIG. 12B is installed on the drive signal generating substrate, and FIG. 12C is installed on the recording head substrate. An example is shown below.

[Explanation of symbols]

1 Printer body 2 recording head 3,15 Control circuit 4 Drive signal generation circuit 5, 6 transistors 7, 8 connector 9, 10, 11 actuator 12, 13, 14 Analog switch 16 Flexible flat cable 16A 1st flexible flat cable 16B 2nd flexible flat cable 17 Conductive pattern 17A Positive side conductive pattern 17B Negative side conductive pattern 18 synthetic resin 19 Variable capacity 20, 21 Inductance 22 Channel unit 23 Nozzle opening 24 nozzle plate 25 Pressure generation chamber 26 Ink supply port 27 Reservoir 28 Flow path forming substrate 29 Piezoelectric vibration unit 30 Piezoelectric vibrator 31 elastic plate 32 cables 33 accommodation room 34 Holder 35 frame 36, 37 internal electrodes 38 segment electrodes 39 Common electrode 40 fixed board 41 Impedance adjusting element 42 Relay board 43, 44 Relay board connector 45, 46, 47, 48, 49 Resistance element 50, 51, 52 Coil element

Claims (9)

[Claims] 1. A recording head provided with a piezoelectric vibrator for expanding and contracting a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets, and drive signal generating means for generating a drive signal for displacing the piezoelectric vibrator. Using a recording head having the same structure, which includes a switching unit that selectively applies the drive signal to the piezoelectric vibrator in accordance with print data and a flexible flat cable that transmits the drive signal to the piezoelectric vibrator, In a plurality of ink jet recording apparatuses having different flat cable lengths, the inductance component of the flexible flat cable between the recording head and the drive signal generating circuit is set to L (μ
H) and the resistance component is R (Ω), the inkjet recording device is characterized in that the ratio of L and R is defined to be substantially the same. 2. The ink jet recording according to claim 1, wherein R of the flexible flat cable is adjusted by changing the thickness of the conductive pattern of the flexible flat cable, and the relationship between L and R of the flexible flat cable is matched. apparatus. 3. In the flexible flat cable, L of the flexible flat cable is adjusted by changing the number of cores of the positive electrode side and the negative electrode side conductive pattern of the drive signal line of the piezoelectric vibrator to adjust L of the flexible flat cable. The inkjet recording apparatus according to claim 1, wherein the relationship between L and R is combined. 4. An L-shaped flexible flat cable is provided by providing an impedance adjustment element in a drive signal transmission path between the drive signal generation circuit and the recording head.
4. The ink jet recording apparatus according to claim 1, wherein the relationship between R and R is combined. 5. The impedance adjusting element is provided on a relay substrate between the recording head and the drive signal generating circuit, and R between the recording head and the drive signal generating circuit is provided.
5. The ink jet recording apparatus according to claim 4, wherein L and R are adjusted so that the relationship between L and R is adjusted. 6. The ink jet system according to claim 4, wherein the impedance adjustment element is provided on the drive signal generation circuit, R between the recording head and the drive signal generation circuit is adjusted, and the relationship between L and R is matched. Recording device. 7. The ink jet recording according to claim 4, wherein the impedance adjusting element is provided on the recording head circuit, R between the recording head and the drive signal generating circuit is adjusted, and the relationship between L and R is matched. apparatus. 8. The ink jet recording apparatus according to claim 4, wherein the impedance adjusting element is a resistance element. 9. The ink jet recording apparatus according to claim 4, wherein the impedance adjusting element is a coil element.