JP2000190488A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the printing quality by reducing the inductance by providing conductive patterns connected to the positive electrode side of switching means and conductive patterns connected to the negative electrode side adjacent with each other in a band-like flexible signal transmitting medium so as to provide the pairs in a number at least same as the number of the switching means. SOLUTION: First conductive patterns 30 of a flexible flat cable 19 connected with the positive electrode of a switching means, and second conductive patterns 31 connected to the negative electrode, to the positive electrode and negative electrode conductive patterns formed in the same order on a substrate, are each connected a semiconductor integrated circuit via the flexible flat cable. Since the first conductive patterns 30 and the second conductive patterns 31 are arrnaged in the same order, the self inductance component and the mutual inductance are in the opposite direction so as to be offset with each other. Accordingly, regardless of the number of piezoelectric oscillators driven simultaneously, a drive signal close to the drive signal wavelength of a drive signal generating means can be supplied to the piezoelectric oscillators.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus having an ink jet recording head for discharging a droplet of ink from a nozzle opening by pressurizing a pressure generating chamber by a pressure generating means, and more particularly to driving the pressure generating means. The present invention relates to a technique for transmitting a signal.

[0002]

2. Description of the Related Art As shown in FIG. 12, an ink jet type recording apparatus is provided with an ink jet type recording head B which presses ink by an actuator and discharges ink droplets from nozzle openings as shown in FIG. The recording head B is supplied with a driving signal of a driving signal generating circuit E via a flexible flat cable D while being reciprocated with respect to C to eject ink droplets.

[0003]

The flexible flat cable D has a length almost twice the moving span of the recording head B in order to ensure the smooth movement of the carriage A. On the other hand, if the number of nozzles of the ink jet recording head B and the number of pressure generating means for pressurizing the pressure generating chamber are increased in order to improve the printing speed, it is necessary to drive many pressure generating means at the same time. Therefore, the current flowing through the flexible cable D increases. Since the back electromotive force due to the inductance component of the flexible flat cable D is proportional to the magnitude of the current and the rate of change with time, a high back electromotive force is generated in the flexible flat cable D that supplies signals to a number of pressure generating means. As a result, the distortion of the drive signal applied to the pressure generating means increases.

Further, in a recording apparatus using a piezoelectric vibrator capable of high printing quality corresponding to photographic quality as a pressure generating means, it is necessary to reduce the amount of ink constituting an ink droplet to about 5 ng. In order to eject ink droplets, it is essential to drive the piezoelectric vibrator at a higher speed than conventional print quality. When the piezoelectric vibrator is driven at a high speed,
Since the time change rate of the current is inevitably increased, the distortion due to the inductance component of the flexible flat cable D increases.

[0005] In order to solve such a problem, it is necessary to reduce the inductance component of the flexible flat cable as much as possible. There is a limit. The present invention has been made in view of such a problem, and an object of the present invention is to improve the print quality by effectively lowering the mutual inductance among the inductance components of the signal supply unit to the pressure generation unit. To provide an ink jet recording apparatus.

[0006]

According to the present invention, there is provided a recording head having pressure generating means for pressurizing a pressure generating chamber which communicates with a nozzle opening for discharging ink droplets. Drive signal generation means for generating a drive signal for operating the pressure generation means, switching means for selectively applying the drive signal to the pressure generation means in accordance with print data, and transmitting the drive signal to the switching means And a first conductive pattern connected to the positive side of each of the switching means and the negative side of the switching means. A logarithm corresponding to at least the number of the switching means is formed adjacent to the second conductive pattern to be connected.

[0007]

The mutual inductance of the conductive pattern for supplying the drive signal from the external drive circuit to the recording head is reduced, so that the current can be increased or decreased in a short time and a drive signal with little distortion is applied to the pressure generating means.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIGS. 1 and 2 show an embodiment of a recording head used in an ink jet recording apparatus of the present invention. A flow channel unit 1 has a plurality of nozzle opening rows in which nozzle openings 2 are formed at a constant pitch. A nozzle plate 3 provided with rows, a pressure generating chamber 4 communicating with the nozzle openings 2, a flow path forming substrate 7 provided with a reservoir 6 for supplying ink to the pressure generating chamber 4 through an ink supply port 5, and a piezoelectric vibrator unit 8. An elastic plate 10 that abuts against the tip of each piezoelectric vibrator 9 in the longitudinal vibration mode to expand and reduce the volume of the pressure generating chamber 4.
And are integrally laminated.

The piezoelectric vibrator unit 8 is a band-shaped flexible signal transmission medium for transmitting an external drive signal,
In this embodiment, after being connected to the flexible flat cable 13, six nozzles are accommodated and fixed in the accommodating chamber 14 by the number of nozzle openings, in this embodiment. In addition, the channel unit 1
Is fixed to the opening surface 12 of the holder 11 formed by injection molding of a polymer material or the like. Then, a frame 15 also serving as a shield material is inserted into the nozzle plate side to constitute a recording head.

The piezoelectric vibrator unit 8 is housed in each housing chamber 14 of the holder 11 as shown in FIG. 3, and then controls the operation of each piezoelectric vibrator 9 in accordance with print data. Is connected to the flexible flat cable 13 on which is mounted. The signal line for controlling the semiconductor integrated circuit 26 is connected to the terminal 17 of the substrate 16 provided on the other surface of the holder 11 via the flexible flat cable 13.

The terminals 17, 17, and # 17 are connected to a connector 18 via a conductive pattern formed on a substrate 16 as shown in FIG. Have been.

In the piezoelectric vibrator 9 of the longitudinal vibration mode constituting the vibrator unit 8, in this embodiment, an internal electrode 20 serving as one pole and an internal electrode 21 serving as the other pole are interposed via a piezoelectric material 22. One having a piezoelectric constant d31 which is laminated in a sandwich shape and has one internal electrode 20 exposed at the front end and the other internal electrode 21 exposed at the rear end, and connected to the segment electrode 23 and the common electrode 24 at each end face. Is configured as

Then, as shown in FIG. 5A, the pressure generating chambers 4 are fixed to a fixed substrate 25 so as to match the arrangement pitch of the pressure generating chambers 4 and are assembled in a unit 8. In this embodiment, the piezoelectric vibrator 9 is configured such that one piezoelectric vibrating plate is divided into comb-shaped teeth so that the rear end side is continuous, and the common electrode 24 of each piezoelectric vibrator 9 is formed as a continuous body. Have been.

The flexible flat cable 13 for connecting each piezoelectric vibrator 9 and the substrate 16 selectively applies a drive signal to each piezoelectric vibrator 9 in a region facing the fixed substrate 25 as shown in FIG. A semiconductor integrated circuit 26 in which semiconductor switching means such as a transfer gate for applying a voltage to the semiconductor integrated circuit and a diode for temperature detection are installed. A diode for temperature detection has a cathode connected in common, and an anode connected to the conductive pattern of the cable 13. A control circuit (not shown) built in the semiconductor integrated circuit 26 generates a piezoelectric vibrator for a drive signal when the switching means is overheated. And outputs a temperature signal for stopping the supply to the power supply.

FIGS. 6 and 7 show the above-mentioned flexible flat cable 1 for connecting an external drive circuit and a recording head.
9 shows an embodiment, in which a first conductive pattern 30, a second conductive pattern 31 connected to the ground, and an arrangement form are shown. In this embodiment, A drive signal is supplied to the semiconductor integrated circuit 26, and the first conductive pattern (COM-x) serving as a positive electrode and the second conductive pattern (GND-x) serving as a negative electrode are arranged in the same order. I have. Then, as shown in FIG. 4, the first conductive pattern 30 and the second conductive pattern 31 of the flexible flat cable 19 are formed of the conductive pattern formed on the substrate 16 and the flexible flat cable 1.
3 are connected to the respective semiconductor integrated circuits 26 (six in FIG. 4).

By arranging in this manner, a current flows as shown by an arrow in FIG. 7 and a magnetic field due to a current of an adjacent conductive pattern is canceled out.
As shown in FIG. 3, the second semiconductor integrated circuit 26 is next to the mirror-symmetric, that is, after the conductive pattern (COM-1) on the positive electrode side and the conductive pattern (GND-1) on the negative electrode side of one semiconductor integrated circuit 26. The conductive pattern (GND-2) on the negative electrode side is next to the conductive pattern (COM-2) on the positive electrode side, and the conductive pattern (COM-3) on the positive electrode side of the third semiconductor integrated circuit 26 is next to it. Thus, the distortion of the drive waveform due to the inductance component is smaller than that of the flexible flat cable D in which the conductive patterns are arranged.

Here, the distortion of the drive waveform due to the inductance component and the effect of the distortion on the ejection of ink droplets will be described. When a trapezoidal drive signal as shown in FIG. 8A is output from the external drive circuit, the drive signal is applied by the semiconductor integrated circuit 26 to the piezoelectric vibrator 9 from which ink droplets are to be ejected. The pressure generating chamber 4 is expanded by contracting the piezoelectric vibrator 9 by the rising portion of the drive signal,
Ink is supplied to the pressure generating chamber 4 via the ink supply port 5.

After the expansion state of the pressure generating chamber 4 is maintained for a predetermined time by the flat part, when the piezoelectric vibrator 9 is discharged by the falling part, the piezoelectric vibrator 9 expands and returns to the original state to generate pressure. The chamber 4 is contracted, and ink droplets are ejected from the nozzle openings 2.

A drive method for ejecting ink droplets suitable for graphic printing by suppressing the ink amount to about 5 ng by positively utilizing the movement phase of the meniscus generated by the expansion of the pressure generating chamber 4 due to the rising portion of the drive signal. In this case, the time T of the flat portion of the drive signal is set to be extremely short, for example, about 2 μsec.

In such a situation, the capacitance of the piezoelectric vibrator 9 and the transmission path of the drive signal, in this embodiment, the self-inductance component of the conductive patterns 30 and 31,
The rise and fall of the current largely depend on the magnitude of the mutual inductance component with the conductive patterns 30 and 31 of the adjacent piezoelectric vibrator 9.

That is, when the drive signal is applied, FIG.
As shown in (b), the back electromotive force ΔE1 due to the inductance component is generated at the beginning of the rising portion, and apparently,
The current starts to flow after a lapse of time ΔT1 from the rising portion of the drive signal. Similarly, at the end of the rising portion, an overshoot occurs due to the electromotive force ΔE2 due to the inductance component.

This tendency is conspicuous when the current flowing through the flexible cable 19 is large, that is, when the number of piezoelectric vibrators 9 that are driven simultaneously is large, for example, when printing a solid image. The amount of ink constituting the droplet increases, which may cause flight bending, missing dots, and the like.

These phenomena also occur at the falling portion of the drive signal. In particular, when the time T of the flat portion is made extremely short as described above in order to eject fine ink droplets, the relative drive signal is reduced. The target distortion is increased, and the ejection characteristics of ink droplets are remarkably reduced.

In the present invention, as described above, the first conductive pattern (COM-x) and the second conductive pattern (G
ND-x) are arranged in the same order, so that the self-inductance component and the mutual inductance component are canceled in opposite directions, regardless of the number of piezoelectric vibrators 9 driven simultaneously. A drive signal close to the drive signal waveform of the drive signal generating means can be supplied to the piezoelectric vibrator 9.
Therefore, the displacement amount and displacement speed of the piezoelectric vibrator 9 can be maintained substantially constant, and printing can be performed with high printing quality.

FIGS. 9A and 9B show another embodiment of the arrangement of the conductive patterns formed on the flexible flat cable 19, respectively. At the boundaries of the first and second conductive patterns (COM-x, GND-x) that supply
The conductive pattern 32 (ANOD-x) connected to the anode of the temperature detecting diode is arranged.

According to this embodiment, when a drive signal is supplied to the piezoelectric vibrator 9 to eject ink droplets, the temperature detection operation is stopped and no current flows through the conductive pattern 32. , A first and a second conductive pattern (COM-x,
GND-x) has an extra distance corresponding to the arrangement space of the conductive patterns 32, so that the mutual inductance between the conductive patterns that supply drive signals to the adjacent piezoelectric vibrators 9 can be reduced.

In the above-described embodiment, one conductive pattern 32 (ANOD-x) connected to the anode of the temperature detecting diode is arranged at the boundary of each piezoelectric vibrator 9, but FIG. As shown in (b) and (b), for each conductive pattern for supplying a drive signal to two semiconductor integrated circuits, in this embodiment, for each four conductive patterns, a conductive pattern connected to the anode of the temperature detecting diode. 32
The same effect is obtained even if a plurality of (ANOD-x), in this embodiment, two are arranged together.

FIG. 11A shows another embodiment of the conductive pattern formed on the flexible flat cable 19. In these embodiments, a positive drive signal is supplied to each semiconductor integrated circuit. 1 conductive pattern 30
Although one (COM-x) is used, the second conductive pattern 31 for supplying the drive signal on the negative electrode side is divided into two (GND-x, GND-x ′).

Further, after the second conductive pattern 31 is divided into two as described above, in the embodiment shown in FIG. 11 (b), each of the two semiconductor integrated circuits is connected to the anode of the temperature detecting diode. Conductive pattern 32 (ANOD-
x), and two in this embodiment.

In these embodiments, since the second conductive pattern 31 is divided into two and the current flowing through one of them is halved, the first conductive pattern of another semiconductor integrated circuit adjacent thereto is divided. The magnetic field interacting with the first conductive pattern 32 is further reduced since the magnetic field interacting with the first conductive pattern 32 is further reduced by the conductive pattern (ANOD-x) according to the configuration of FIG. Since the number is further reduced, the mutual inductance of the entire flexible flat cable 19 can be reduced.

In the above-described embodiment, the case where a drive signal is supplied to the piezoelectric vibrator has been described. However, an ink-jet type in which a Joule heat generating element is disposed in a pressure generating chamber to discharge ink droplets by vaporization of ink. Obviously, the same effect is achieved even when applied to a flexible flat cable of a recording head.

Further, for example, in order to print text at high density, the pitch of the nozzle openings for color printing is set to 2/2.
In a recording head in which a row of nozzle openings for black is formed, no drive signal is supplied to one of the piezoelectric vibrator units for discharging black ink in order to make the dot pitch uniform during color printing.

In such a recording head, when a flexible flat cable is folded and stacked, or when two independent flexible flat cables are stacked and used in a two-layer structure, a piezoelectric vibrator for discharging color ink is used. When the drive signal supplied to the unit is supplied by one layer, and the drive signal is supplied by the other layer to the black ink discharging piezoelectric vibrator unit which does not discharge ink droplets during color printing, even if the conductive pattern of each layer is overlapped The effect of mutual inductance can be eliminated.

[0034]

As described above, in the present invention,
A first conductive pattern connected to the positive electrode side of the switching means and a second conductive pattern connected to the negative electrode side of the switching means are adjacent to the belt-shaped flexible signal transmission medium, and at least a logarithm corresponding to the number of the switching means. Since it is formed, the mutual inductance of the conductive pattern that supplies the drive signal to each switching means can be reduced, and the rise delay and overshoot of the drive signal can be suppressed as much as possible. Photographic quality solid images can be printed with high print quality.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view showing an embodiment of a recording head according to the present invention.

FIG. 2 is a diagram showing a cross-sectional structure in one pressure generating chamber of the recording head.

FIG. 3 is a cross-sectional view showing one embodiment of the recording head.

FIG. 4 is a top view showing one embodiment of a substrate fixed to the recording head.

FIGS. 5A and 5B are diagrams showing an embodiment of the vibrator unit in a state where a flexible flat cable is removed and a state where a flexible flat cable is connected, respectively.

FIG. 6 is a view showing an embodiment of a flexible flat cable for connecting an external drive circuit and a recording head in a state where a cover coat is peeled off and a conductive pattern is exposed.

FIG. 7 is a view schematically showing one embodiment of a conductive pattern formed on the flexible cable.

FIG. 8A shows a signal waveform of a drive signal generating source, FIG. 8B shows a drive signal applied to a piezoelectric vibrator by a conventional flexible cable, and FIG. FIG. 4 is a diagram illustrating a drive signal applied to a piezoelectric vibrator.

FIGS. 9A and 9B are diagrams schematically showing another embodiment of the conductive pattern formed on the flexible flat cable, respectively.

FIGS. 10A and 10B are diagrams schematically showing another embodiment of the conductive pattern formed on the flexible flat cable, respectively.

FIGS. 11A and 11B are diagrams schematically showing another embodiment of the conductive pattern formed on the flexible flat cable, respectively.

FIG. 12 is a diagram showing one embodiment of an ink jet recording apparatus.

FIG. 13 is a diagram schematically illustrating an example of a conductive pattern formed on a flexible flat cable of the ink jet recording apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 flow path unit 8 vibrator unit 9 piezoelectric vibrator 16 substrate 19 flexible flat cable 26 semiconductor integrated circuit 30 first conductive pattern 31 second conductive pattern 32 conductive pattern connected to temperature detecting diode

Claims (11)

[Claims] A recording head having pressure generating means for pressurizing a pressure generating chamber communicating with a nozzle opening for discharging ink droplets; a driving signal generating means for generating a driving signal for operating the pressure generating means; and printing. Switching means for selectively applying the drive signal to the pressure generating means in response to data, and an ink jet recording apparatus comprising a belt-shaped flexible signal transmission medium for transmitting the drive signal to the switching means, A first conductive pattern connected to the positive electrode side of each of the switching means and a second conductive pattern connected to the negative electrode side of the switching means are adjacent to the strip-shaped flexible signal transmission medium, and at least the number of the switching means is reduced. An ink jet recording apparatus in which a logarithm corresponding to is formed. 2. The ink jet recording apparatus according to claim 1, wherein the first conductive pattern and the second conductive pattern are arranged in a permutation. 3. The switch according to claim 1, wherein at least one third conductive pattern connected to the temperature detecting means for detecting the temperature of the switching means is arranged between the conductive patterns connected to the adjacent switching means. Inkjet recording device. 4. A first conductive pattern and a second conductive pattern connected to adjacent switching means are arranged so as to be mirror-symmetrical, and the first and second conductive patterns corresponding to each pressure generating means are provided.
4. The ink jet recording apparatus according to claim 3, wherein at least one third conductive pattern connected to the temperature detecting means for detecting the temperature of the switching means is formed between the second conductive pattern and the second conductive pattern. 5. The ink jet recording apparatus according to claim 1, wherein the second conductive pattern is divided into two. 6. A method according to claim 1, wherein at least one third conductive pattern connected to the temperature detecting means for detecting the temperature of the switching means is formed between the second conductive patterns connected to the adjacent switching means. 6. The ink jet recording apparatus according to 5. 7. The ink jet recording apparatus according to claim 1, wherein said belt-shaped flexible signal transmission medium is constituted by a flexible flat cable. 8. An ink jet recording apparatus according to claim 3, wherein said temperature detecting means comprises a diode. 9. An ink jet recording apparatus according to claim 1, wherein said pressure generating means comprises a piezoelectric vibrator which expands and contracts in an axial direction. 10. The piezoelectric vibrator unit according to claim 1, wherein the piezoelectric vibrator is configured as a piezoelectric vibrator unit fixed to a fixed substrate, and the independent flexible flat cable is connected to each unit. The ink-jet recording apparatus as described in the above. 11. An ink jet recording apparatus according to claim 1, wherein said pressure generating means comprises a Joule heat generating element provided in said pressure generating chamber.