JPS5859855A - Driving circuit for ink jet printer - Google Patents

Abstract

PURPOSE:To reduce the number of drivers, etc., of a drive circuit for ink jet printer by such an arrangement wherein No.1 and No.2 switching elements which open or close the supply of electricity to inductive elements are connected in parallel with plural sets of serial circuits of diodes and piezoelectric elements respectively and also connected in series with the inductive elements. CONSTITUTION:When a transistor Xm for scanning is turned on by a control circuit at a specified cycle, a counter electromotive voltage caused by the on and off of a transistor Yn for selection is charged in piezoelectric elements P(m, n), and after that the piezoelectric element P is caused to discharge by turning Yn on. Here, a diode D(m, n) is used by normal multiplex drive and operates to prevent an erroneous operation of the circuit by the access of non- selected piezoelectric elements, to charge the piezoelectric element P with a counter electromotive voltage of inductance Ln and maintain it at a high voltage as it is. By this arrangement, it is possible to obtain an ink jet drive circuit without using expensive booster circuits which is less in the number of drivers and inductance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink-on-demand type inkjet using a pressure element, and particularly to a drive circuit for a multi-nozzle head.

Ink-on-demand type inkjet has advantages such as low printing energy and comparatively easy production of multi-nozzle heads; however, piezoelectric element T + &
The downside is that more than J&tg+v is required, and in devices that use batteries as a power source, the booster circuit and driver become expensive.

If a large number of nozzles are used, the driver cost will also increase accordingly.

Therefore, an object of the present invention is to eliminate the need for an expensive booster circuit.

The purpose of the present invention is to reduce the number of drivers in a multi-nozzle head.

Figure 1 shows a multi-nozzle t in which the drive circuit of the present invention is used.
FIG. 2 is a diagram showing an example of an inkjet head with a printer.

1 is an intermediate substrate made of a material such as glass or glass, and includes a pressure chamber, an ink flow path, and a nozzle 411! groove-like traps are formed on both sides.

2 and S are peristaltic plates arranged so as to sandwich the intermediate substrate 1; PFi piezoelectric elements Kk located opposite the pressure chambers formed in the intermediate substrate 1 are peristaltic plates arranged on the drive plate and 3; The drive circuit according to the invention is not limited to the structure shown in FIG. 1, and may have pressure chambers and nozzles formed only on one surface of the substrate, and is applicable to all inkjet heads having a structure having a plurality of nozzles. t+, since the operations of these heads are already well known, their explanation will be omitted.

FIG. 2 is a diagram showing an embodiment of the drive circuit of the present invention.

This example shows the case where four piezoelectric elements are driven in a 2×2 multiplex. Of course, if there are four piezoelectric elements, four drivers are required without multiplex driving, and multilux driving is particularly advantageous. However, as the number of piezoelectric elements increases, the advantage of multiplexing, in which 1MXN piezoelectric elements are driven by M+N drivers, becomes obvious.

In Figure 2, Xl, X2 scanning transistors, Y
l and Yl are selection transistors, Ppm.

n) is a pressure 11 element selectively driven δ by scanning transistors X, m and selection transistor Yn, and D(m, n
) a pressure connected in series to element P (m, n) diode d (m, n) u pressure m8 child P [m.

n] and a diode connecting the selection transistor Yn,
Ll and L2 are diodes D (m, n).

Selection transistor Y1゜Yl via d(,m,n)
An inductance connected in series with Dl.

Dl is a diode connected in parallel with the scanning transistor.

In the above configuration, the seventh operation will be explained.

The scanning transistors Xm are turned on one after another at a constant repetition period by a control circuit (not shown). Synchronized with the scanning of Xm, Yn is selected by a control circuit (not shown) based on the pattern to be recorded.
As an example of zero in which the scanning transistor X1 and the selection transistor Y1 are on, the scanning transistor x1 is turned on at time T.times.11, which will be explained in FIG.

Next, at time TI, the selection transistor Y1 is turned on.

When Yl turns on, diodes D[1°1] and d(1
, 13, and DC2,1) and d(2,l1t-) to inductance -1 (voltage v6). After a predetermined time, the selection transistor Y1 is turned off (time Tx). At this time, the inductance LIK generated back electromotive voltage Vsij charges the floor electric element P (1,1) via the diode D (1,1).The pressure IIE element P[2,lli
, the scanning transistor/X2 is off, so it is not charged.

In this way, Xl and Yl are selected and the voltage is 1! Kiko p (
1, t) is driven, Xl is turned off at time T4, and a predetermined time has elapsed from time T8, at time TsK)?
Turn on register Y1. Piezoelectric element P[:1. t]x The charged charges are transferred to the diode d(1,1) and Dl
is discharged through. Transistor Y at 1+time T6
1/l'i is turned off. Yl off (1 time T from /C
Similar to 2, a trap back electromotive force is generated, but 11. Since both X2 are off, all piezoelectric elements are not charged.

As described above, when the scanning transistor , n).

Second, as can be seen in the implementation of FIG.
[m, n)11 il! due to wraparound of unselected piezoelectric elements used in normal multiplex driving. 'It not only has the function of completely preventing operation (but also has the role of charging the back electromotive force of the inductance Ln to the piezoelectric element P (m, n) and maintaining it at a high voltage.Diode Dam,
n) without QFi inductance Ln and pressure wLX element P[
The pulse width determined by the attenuation imaging determined by the TJC with the ate of :m, n) is the only pulse applied to the piezoelectric element, but the diode D(m, n) holds the pulse at a high voltage and lengthens the pulse width applied to the piezoelectric element. can. Next, the injector can be easily driven even with a small inductance.

In the embodiment shown in FIG. 2, the transistor X1. Depending on the characteristics of X2, it is possible to reverse current from the transistor's collector to the collector even without the diodes DI and D2, and in this case, the circuit becomes simpler. Of course, the transistors In and Yn are connected to other switching elements, such as seR,
) Raiatsuku etc. may be used.

Another modified embodiment of the present invention is shown in FIG.

In this example one inductance LK) transistor T
The back electromotive voltage is generated at o, and the six transistors T (
The piezoelectric element PK is charged via the diode D'i by the transistor T which is selectively turned on (in the figure, one symbol is given as a representative). R is a discharge resistor, and the element PK is charged with the additional pressure, and the specific charge is discharged by the discharge resistor R with a time constant determined by the gtc of the piezoelectric element P and the discharge resistor RK.

Therefore, the voltage tS: the voltage applied to the child P is the fifth (ii!J
By appropriately selecting the discharge resistance Pi as shown by 0, it is possible to eject ink even with a pulse as shown in FIG.

In the example of FIG. 4, a total of seven transistors are required to drive six piezoelectric elements, and the driver a is disadvantageous because it is larger than when driving each piezoelectric element individually.

However, only one inductance LtFi is good (,
There is a cost advantage if the transistor has low payne inductance. Note that the first discharge resistor is used instead of just the discharge resistor.
A discharge transistor can be provided as in the example shown in the figure.

FIG. 6 shows an embodiment of the pond of the present invention. In this example, discharge is caused by the discharge of the piezoelectric element shown in FIG. 1, and discharge is caused by the discharge resistor shown in FIG. 4.

Discharge resistance R [: m] is connected to each element P (m, n) in series.

n], the diode a(m
, n) and Dm are omitted to reduce the price. Instead, energy is consumed by the discharge resistor R (m, n), and the drive waveform is not a rectangular wave but the waveform shown in the fifth @, so that it is less advantageous than the example shown in FIG. 2 in terms of energy.

As can be seen from the above explanation, by applying a back electromotive force caused by an inductance to the piezoelectric element via a diode, it is possible to obtain the voltage and pulse width necessary for ejecting ink, and to perform multi-grain driving without wraparound. Therefore, an inksheet drive circuit with a small number of drivers and inductances and no need for an expensive booster circuit is obtained, and can be widely applied to printers with multi-nozzle heads, 10-inch printers, facsimile machines, copiers, etc.

[Brief explanation of drawings]

#! FIG. 1 is a diagram showing a part of an inkjet head adapted to the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. #13 Figure #1lK2 Operation of the circuit in Figure t--Timing explained ljM diagram, Figure 4 is a circuit diagram showing another embodiment of the present invention, Figure 5 Fi
FIG. 4 is a diagram showing the voltage waveform applied to the pressure Im element of the embodiment, and FIG. 6-d is a diagram showing the implementation IPIJ of the pond of the present invention. L, 'Ln-...Inductance, P, P(m, n
)...Piezoelectric element, DI D (m, n)-...Diode. Xm---scanning transistor, Yn---selection transistor, T, T@-) transistor. Figure 1: Figure 4V 115 Figure 68

Claims (1)

[Scope of Claim] A multi-nozzle inkjet printing device that changes the volume of a pressure chamber according to an application to a piezoelectric element and a signal, and performs recording by ejecting ink droplets from a nozzle, comprising an inductive element and a limb inductive element. a first switching element that opens and closes energization to the piezoelectric element; and a plurality of sets in which a diode and a second switching element are connected in series on the piezoelectric element;
A drive circuit for an inkjet printing apparatus, wherein the plurality of series-connected sets are each connected in parallel and connected in series with the inductive element.