JPH07137291A - Ink residue detector for ink storage means - Google Patents

Abstract

PURPOSE:To realize a reduction in size of an apparatus having high detecting sensitivity, high reliability of ink residue decision and no change of quality by applying a driving voltage to a first piezoelectric member by a driving circuit to deform it, and detecting a counterelectromotive force obtained by deforming a second piezoelectric member by a pressure wave generated in ink between first and second piezoelectric members to decide an ink quantity. CONSTITUTION:When an ink residue in an ink cartridge is reduced and a gap occurs between an ink surface and an upper plate 150 in a pressure chamber 160, even if a first piezoelectric member 110 is deformed to shrink the chamber 160, the air in the chamber 160 shrinks that much so as not to contribute to reduction in a volume of the ink, and a level of a pressure wave generated in the ink in the chamber 160 is extremely lowered as compared with the case where the chamber 160 is filled with ink. Thus, a level of a counterelectromotive force V1 generated at a second piezoelectric member 120 and to be applied to a non-inverting input terminal of an operational amplifier 310 is remarkably reduced. Then, when an enable signal rises, switch means turns on to make current flow through an alarm generator, thereby generating an alarm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer using liquid ink, such as an ink jet printer, and more particularly to a device for detecting the remaining amount of ink in an ink storage means of the printer.

[0002]

2. Description of the Related Art Printers using liquid ink, such as ink jet printers and electrostatic printers, are currently widely used because they can print with high quality and with low noise. However, since printing is performed using ink, when a large amount of printing is performed, the ink runs out, and it is necessary to replace the ink storage means such as the ink cartridge or the ink tank or replenish the ink to the ink storage means. If this ink shortage occurs during the printing operation, trouble will occur and the work efficiency will be impaired.

Therefore, in order to prevent the ink from running out, an ink remaining amount detecting device for predicting the ink running out has been devised and is already known. As a conventional ink remaining amount detecting device, for example, in Japanese Utility Model Publication No. 62-37733,
A first means for measuring the change in capacitance between the electrodes by immersing two electrodes in the ink, and a second means for measuring the change in electric resistance of the ink by two needles provided in the ink are provided. Have been described.

However, in the first means, the absolute value of the capacity change is decisively small due to the size restriction of the ink storage means, and the measurement accuracy is extremely unstable. The second means causes a current to flow through the ink, which promotes a chemical change in the ink, which deteriorates the printing characteristics of the ink and easily causes deterioration of the printing quality.

In addition to this, there is also known a third means for detecting a change in the amount of received light by interposing ink directly between the light emitting means and the light receiving means or indirectly through a container. However, the third means has the drawback that the detection accuracy is low due to the wetting of the ink, and the device is likely to be large.

[0006]

It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art in an ink remaining amount detecting device of an ink storing means for predicting ink shortage, to have high detection sensitivity, and to reliably judge the level of the ink remaining amount. It is an object of the present invention to provide a technique capable of realizing a device having high property and not causing deterioration of ink even in a small size.

[0007]

In order to achieve the above object, the present invention is an ink remaining amount arranged in an ink storage means of a printer device, which comprises two piezoelectric members facing each other, a drive circuit and a detection circuit. In the detection device, a drive voltage is applied to the first piezoelectric member by the drive circuit to deform the first piezoelectric member, and a pressure wave is generated in the ink interposed between the first and second piezoelectric members. The second piezoelectric member is deformed to generate a back electromotive voltage, and the back electromotive voltage is detected by the detection circuit to determine the level of the remaining ink amount.

The present invention further provides an ink remaining amount detecting device arranged in the ink storing means of a printer device, which comprises a piezoelectric vibrating member, an oscillation circuit for vibrating the piezoelectric vibrating member, and a detection circuit for detecting the output of the oscillation circuit. It is characterized in that the level of the remaining ink amount is determined by the detection circuit.

[0009]

According to the present invention, the first of the first and second piezoelectric members arranged in the ink storage means and facing each other
By applying a drive voltage to the piezoelectric member, the piezoelectric member is deformed, the ink interposed between the first and second piezoelectric members is compressed, and a pressure wave is generated in the ink. Then, the pressure wave deforms the second piezoelectric member to generate a counter electromotive voltage, and the counter electromotive voltage is detected by the detection circuit.

Therefore, the level of the pressure wave and the level of the counter electromotive voltage depending on it depend on the level of ink between the first and second piezoelectric members even if the piezoelectric member is small. Change extremely sharply. Therefore, the measurement sensitivity is high and the reliability is high.

Further, it is possible to apply a voltage to the first piezoelectric member or take out a counter electromotive voltage from the second piezoelectric member without passing a current through the ink, so that the quality of the ink does not change. In this way, when the remaining amount of ink is below a certain level, the back electromotive force is significantly lowered, and the insufficient state of the remaining amount of ink can be easily detected.

Further, according to the present invention, by disposing the piezoelectric vibrating member inside the ink storage means and forming the oscillation circuit by using the piezoelectric vibrating member as a part of the circuit, for example, when ink is dipped in the piezoelectric vibrating member. By setting the gain of the oscillation circuit so that it does not oscillate and oscillates when it is not immersed, even with a small piezoelectric vibrating member, the deterioration of the ink does not occur, and the remaining amount of ink is too low with stable measurement accuracy. The state can be detected.

[0013]

First Embodiment A first embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3. 1 is a perspective view showing an overall configuration of a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a drive circuit of the first embodiment of the present invention, and FIG. 3 is a detection diagram of the first embodiment of the present invention. FIG. 4 is a circuit diagram showing a circuit, and FIG. 4 is a time chart showing an operation of the first embodiment of the present invention.

In FIG. 1, a plate-shaped first piezoelectric member 110 and a second piezoelectric member 12 made of a piezoelectric material such as PZT are provided on a substrate 101 attached to the ink storage means 100.
0s are arranged and fixed so as to face each other. The upper plate 150 is commonly attached to the upper ends of the first piezoelectric member 110 and the second piezoelectric member 120 via the elastic member 140.

A pair of drive electrodes 112 and 114 are attached to the side surfaces of the first piezoelectric member 110 with the first piezoelectric member 110 interposed therebetween.
A pair of detection electrode 122 and detection electrode 124 are attached to the side surface of the second piezoelectric member 120 with the second piezoelectric member 120 interposed therebetween. The first piezoelectric member 110 and the second piezoelectric member 120 are polarized in the direction of arrow 126.

The drive electrodes 112 and 114 are connected to the first output terminal 201 and the second output terminal 203 of the drive circuit 200 by lead wires, respectively. Detection electrode 122,
The lead wires 124 are connected to the input terminal 301 of the detection circuit 300 and the ground by lead wires.

The drive circuit 200 and the detection circuit 300 can be provided inside or outside the ink storage means 100. For example, the drive circuit 200 is provided outside and a part of the drive circuit for printing is switched and used. Circuit 300
It is practical to place some of them inside and the rest outside.

Explaining the structure of the drive circuit 200, as shown in FIG. 2, the first output terminal 201 connected to one drive electrode 112 of the first piezoelectric member 110 is connected to the positive power supply line HV. To do. The second output terminal 203 connected to the drive electrode 114 facing the drive electrode 112 has a resistance R
2. Connected to the ground via the first npn bipolar transistor 202, and connected to the positive power supply line HV via the resistor R1 and the pnp bipolar transistor 205. The pnp bipolar transistor 205 has its base connected to the positive power supply line HV via the resistor R3 and is connected to the ground via the resistor R4 and the second npn bipolar transistor 207.

Explaining the structure of the detection circuit 300, as shown in FIG. 3, one detection electrode 122 of the second piezoelectric member 120 is connected to the operational amplifier 3 via the input terminal 301.
The other one of the detection electrodes 1 connected to the non-inverting input terminal 10
24 are connected to the ground via lead wires, respectively.

The inverting input terminal of the operational amplifier 310 is connected to the positive power supply line HV via the resistor R31 and is also connected to the ground via the resistor R32. Operational amplifier 310
The output terminal of is connected to the T terminal of the flip-flop 330 via the diode 320 and the resistor R33, and this T terminal is connected to the ground via the resistor R34.

The reset signal line 332 is connected to the reset terminal of the flip-flop 330. The Q terminal of the flip-flop 330 is connected to the inverting input terminal of the AND gate 340, and the enable signal line 342 is connected to the non-inverting input terminal of the AND gate 340.

The output terminal of the AND gate 340 is connected to the control section G of the switch means 356 of the alarm generation circuit 350 which is composed of the power source section 352, the load 354 and the switch means 356. Here, the power supply unit 352 is a DC power supply or an AC power supply, the load 354 is a light emitting means or a sound generating means, and the control unit G of the switch means 356 is, for example, a base of an npn bipolar transistor.

The operation of the first embodiment of the present invention will be described.
When there is a sufficient amount of ink remaining in the ink storage means 100 such as an ink cartridge, the substrate 101 shown in FIG.
4B surrounded by the piezoelectric member 110 and the second piezoelectric member 120 of FIG.
Ink is filled like in 0.

The distance between the first piezoelectric member 110 and the second piezoelectric member 120 is such that the height of the liquid surface of the ink in the pressure chamber 160 avoids the effect of capillary action and the ink storage means 100.
It is preferable to set it to about 1 mm so as to follow the height of the liquid surface of the ink inside.

The charge signal N and the discharge signal P0 shown in FIG. 4A are applied to the bases of the first npn bipolar transistor 202 and the second npn bipolar transistor 207 of the drive circuit shown in FIG. 2, respectively.

While the discharge signal P0 is rising, discharge is generated between the drive electrodes 112 and 114, and the first
The drive voltage V applied to the piezoelectric member 110 is zero level. Period T1 during which the charging signal N is rising
In this case, charging is performed between the drive electrodes 112 and 114, the potential of the drive electrode 114 is lowered to the ground level, and the drive voltage V applied to the first piezoelectric member 110 is the power supply of the power source after the elapse of the charging time constant. Rise to a level equal to the voltage. Next, when the discharge signal P0 rises, discharge is performed in the same manner as before, and after a period determined by the discharge time constant, the drive voltage V drops to the zero level.

As described above, during the period when the drive voltage V is rising, the first piezoelectric member 110 is deformed by the shear mode (shear strain) in the direction of the double arrow 128 in FIG. 1 to shrink the pressure chamber 160, As a result, the pressure of the ink with which the pressure chamber 160 is filled rises rapidly and a pressure wave is generated.

The pressure chamber 160 and the ink storage means 100 communicate with each other for inflow and outflow of ink, but can be regarded as closed for pressure waves. Therefore, this pressure wave is transmitted to the second piezoelectric member 120 and deforms it. As a result of this deformation, a gap between the detection electrodes 122 and 124 shown in FIG.
The counter electromotive voltage V1 shown in (b) is generated.

This back electromotive force is applied between the ground and the non-inverting input terminal of the operational amplifier 310 in the detection circuit shown in FIG. Here, the voltage applied between the inverting input terminal of the operational amplifier 310 and the ground is E * R32 / (R31 + R32) when the power supply voltage is E, and this is E0
And When the peak value of the back electromotive force V1 is E1, the E0 is set to an appropriate value lower than E1.

In this way, the output voltage V2 of the operational amplifier 310 becomes -E when the counter electromotive voltage V1 is lower than the voltage E0 at the inverting input terminal, as shown in FIG.
Since it becomes + E during a period exceeding E0, the positive signal pulse P1 is input to the T terminal of the flip-flop 330 via the diode 320 and the resistor R33.

When a reset signal is applied to the reset terminal of the flip-flop 330 in advance through the reset signal line 332 and the data at the Q terminal of the flip-flop 330 is reset to low, the flip-flop is caused by the fall of the signal pulse P1. The data at the Q terminal of 330 rises from low to high, and this state is maintained, so that the data at the inverting input terminal of the AND gate 340 is maintained at the high state.

In this state, the enable signal Q31, which rises after being shifted by an appropriate time after the charge signal N of the drive circuit 200 is applied, is the enable signal line 34.
2, but the output data QG of the AND gate 340 applied to the control section G of the switch means 356 is still low as before the enable signal Q31 rises, the switch means 356 remains non-conducting, No current flows through the alarm generation circuit 350 and no alarm is generated.

Next, when the remaining amount of ink in the ink cartridge becomes small and a gap is created between the ink surface and the upper plate 150 in the pressure chamber 160 as shown in FIG. The piezoelectric member 110 of No. 1 is deformed and the pressure chamber 1
Even if 60 is reduced, the air in the pressure chamber 160 is reduced by that much, and it hardly contributes to the reduction of the volume of the ink, and the level of the pressure wave generated in the ink in the pressure chamber 160 is as described above. Compared with the case where the pressure chamber 160 is filled with ink, the pressure drops extremely.

Along with this, the level of the back electromotive force V1 generated in the second piezoelectric member 120 and applied to the non-inverting input terminal of the operational amplifier 310 is remarkably lowered, and its peak value is reached, as shown in FIG. 4 (c). Also, the voltage becomes lower than the voltage E0 of the inverting input terminal of the operational amplifier 310. As a result, the output voltage of the operational amplifier 310 is always −E, and the flip-flop 33 passes through the diode 320 and the resistor R33.
The level of the signal P1 input to the T terminal of 0 becomes low,
The data at the Q terminal of the flip-flop 330 remains reset low.

When the enable signal Q31 rises, the output data of the AND gate 340 rises from low to high, the switch means 356 becomes conductive, a current flows through the alarm generating circuit 350, and an optical or acoustic alarm is generated.

Since the elastic member 140 is soft, even if the first piezoelectric member 110 is deformed, the deformation hardly contributes to the deformation of the second piezoelectric member 120 via the upper plate 150.

As described above, according to the apparatus of the first embodiment of the present invention, the alarm can be reliably generated only when the ink remaining amount becomes less than the predetermined value. This device is used by being incorporated in a printer. For example, if the device is operated prior to printing and the ink cartridge is replaced when an alarm is issued, ink will run out. Can be prevented.

[0038]

Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. 5, 6 and 7. FIG. 5 is a perspective view showing a configuration of an apparatus according to a second embodiment of the present invention, and FIG. 6 is a second embodiment of the present invention.
FIG. 7 is a circuit diagram showing the detection circuit of FIG. 7, and FIG. 7 is a time chart showing the operation of the second embodiment of the present invention.

The sensor part of the second embodiment of the present invention is a vertical version of the sensor part of the first embodiment shown in FIG.
The substrate 101 is provided inside the side wall of the ink storage means 100.
The first piezoelectric member 110 and the second piezoelectric member 120 are attached so that their plate surfaces are perpendicular to the ink surface.
Similar to the first embodiment, a common upper plate is attached to the first piezoelectric member 110 and the second piezoelectric member 120 via an elastic member, but the elastic member and the upper plate are not shown.

Drive electrode 1 provided on the first piezoelectric member 110
12 and 114 are respectively connected to the drive circuit 20 by a lead wire.
0 first output terminal 201 and second output terminal 203
Connect to. Detection electrode 1 provided on the second piezoelectric member 120
22 and 124 are respectively connected to the detection circuit 40 by a lead wire.
0 input terminal 401 and ground.

The structure of the detection circuit 400 will be described. As shown in FIG. 6, one detection electrode 122 of the second piezoelectric member 120 is connected to the operational amplifier 3 via the input terminal 401.
The other one of the detection electrodes 1 connected to the non-inverting input terminal 10
24 are connected to the ground via lead wires, respectively.

The inverting input terminal of the operational amplifier 310 is a resistor R
It is connected to the positive power supply line HV via 31 and is connected to the ground via the resistor R32. The output terminal of the operational amplifier 310 is connected to the non-inverting input terminal of the second AND gate 450 via the diode 320 and the resistor R33, and the non-inverting input terminal is connected to the ground via the resistor R34.

The inverting input terminal of the second AND gate 450 is connected to the Q terminal of the flip-flop 330 and the inverting input terminal of the first AND gate 340. The output terminal of the second AND gate 450 is connected to the T terminal of the flip-flop 330.

The reset signal line 332 is connected to the reset terminal of the flip-flop 330. The enable signal line 342 is connected to the non-inverting input terminal of the first AND gate 340.

The output terminal of the first AND gate 340 is
It is connected to the control unit G of the switch unit 356 of the alarm generation circuit 350 including the power supply unit 352, the load 354, and the switch unit 356.

The operation of the second embodiment of the present invention will be described.
The drive circuit 200 of the second embodiment of the present invention is the same as the drive circuit of the first embodiment. By repeating the same driving method as that of the first embodiment, the driving voltage V having the same waveform as shown in FIGS. 7A and 7B is repeatedly applied to the first piezoelectric member 110 at a constant cycle. As a result, the first piezoelectric member 110 is excited and a continuous wave is generated in the ink, and the second piezoelectric member 120 is excited by this wave and the counter electromotive voltage V2 of AC is generated.
1 is generated.

When the remaining amount of ink in the ink storage means is sufficient, the ink is completely or sufficiently present in the pressure chamber 160 as shown in FIG. 7 (a). At this time, E0 is appropriately set so that the peak value of the AC back electromotive voltage V21 generated in the second piezoelectric member 120 exceeds the voltage E0 of the inverting input terminal of the operational amplifier 310 which is determined by the voltage division ratio of the resistors R31 and R32. Set it.

In this way, the output voltage of the operational amplifier 310 becomes + E when the counter electromotive voltage V21 exceeds E0, and becomes -E when the counter electromotive voltage V21 exceeds E0.
After 33, the pulse signal P2 is repeatedly input to the non-inverting input terminal of the second AND gate 450 at the same cycle as the counter electromotive voltage V1.

A reset signal is previously applied to the reset signal line 332 of the flip-flop 330, and the flip-flop 3
The data Q at the Q terminal of 30 is initially set low. When the first pulse of the pulse signal P2 is applied in this state, the output data QT of the second AND gate 450 input to the T terminal is initially in a low state, and when P2 rises it becomes high and when P2 falls, it becomes low. Becomes

As soon as the data at the T terminal of the flip-flop 330 falls from high to low in this way, the data at the Q terminal of the flip-flop 330 rises from low to high and the inverting input terminal of the second AND gate 450 Since the data becomes high, the output data QT of the second AND gate 450 remains low even when the second and subsequent pulses of P2 come, and therefore the data Q at the Q terminal of the flip-flop 330 also maintains the high state. However, the input signal in the high state is continuously applied to the inverting input terminal of the first AND gate 340.

In this state, even if the enable signal Q31 is applied to the enable signal line 342, the first AND gate 3
The output QG of 40 is still low as before the enable signal Q31 rises, the switch means 356 remains in the non-conducting state, no current flows through the alarm generating circuit 350, and no alarm is generated.

Next, the remaining amount of ink in the ink cartridge becomes small, and as shown in FIG.
As the piezoelectric member 110 and the second piezoelectric member 120 approach the lower ends, the level of the wave motion generated by the vibration of the first piezoelectric member 110 decreases, so the second piezoelectric member 1
It becomes difficult for 20 to be vibrated by a wave. Therefore, the vibration amplitude of the second piezoelectric member 120 decreases, and the peak value of the counter electromotive voltage V21 also decreases accordingly.

As a result, when the level of the ink surface falls below a predetermined level, the peak value of the back electromotive force V21 becomes less than the voltage E0 at the inverting input terminal of the operational amplifier 310, and the output voltage of the operational amplifier 310 always becomes -E, and the diode 32.
Second AND gate 450 via 0 and resistor R33
The input signal P2 to the non-inverting input of the flip-flop 330 is always low, the input QT to the T terminal of the flip-flop 330 is always low, and the data Q at the Q terminal of the flip-flop 330 maintains the low state and the first AND gate The input in the low state is continuously applied to the inverting input terminal of 340.

When the enable signal Q31 is applied to the enable signal line 342 in this state, the output QG of the AND gate 340 is output while the enable signal Q31 is rising.
Becomes high, the switch means 356 is turned on, a current is passed through the alarm generation circuit 350, and an alarm is generated.

[0055]

Third Embodiment A third embodiment of the present invention will be described with reference to the drawings. 8 is a perspective view showing the configuration of the device of Embodiment 3 of the present invention, FIG. 9 is a circuit diagram showing an oscillator circuit and a detection circuit of Embodiment 3 of the present invention, and FIG. 10 is an embodiment of the present invention. 3 is a time chart explaining the operation of No. 3;

A plate-shaped piezoelectric vibrating member 130 made of a piezoelectric material such as PZT is erected and fixed on a substrate 101 mounted inside the ink storage means 100. A pair of electrodes 132 and 134 are attached to the side surfaces of the piezoelectric vibration member 130 with the piezoelectric vibration member 130 interposed therebetween. The electrodes 132 and 134 are connected to the oscillation circuit 500 by leads, and the output terminal 503 of the oscillation circuit 500 is connected to the input terminal 411 of the detection circuit 410 by leads.

The configurations of the oscillation circuit 500 and the detection circuit 410 will be described with reference to FIG. In the oscillation circuit 500, one electrode 132 of the piezoelectric vibrating member 130 is connected to the collector of the npn bipolar transistor 522 via the capacitor C2, and the other electrode 134 is connected to the base of the npn bipolar transistor 522.

The collector of the npn bipolar transistor 522 is connected to the positive power supply line HV via a separate impedance Z61, and the output terminal 50 is connected by a lead wire.
Connect to 3. The base of the npn bipolar transistor 522 is connected to the ground via the capacitor C1, and
Further, the base of npn bipolar transistor 522 is connected to positive power supply line HV and ground via bias resistor R51 and bias resistor R52, respectively.

The emitter of npn bipolar transistor 522 is connected to ground via impedance Z62. As shown in FIG. 9, the configuration of the detection circuit 410 is the same as that of the second embodiment except that the first AND gate 340 shown in FIG. 6 is omitted and the Q terminal of the flip-flop 330 is connected to the gate section G of the switch means 356. Since it is similar to the circuit 400, detailed description is omitted.

The operation of the present invention will be described. In the oscillator circuit 500 of FIG. 9, the fluctuation of the counter electromotive voltage generated between the electrodes 132 and 134 causes the fluctuation of the base-emitter current of the npn bipolar transistor 522, and the fluctuation of the collector current of the npn bipolar transistor 522 in an amplified form. Which causes the collector potential of the npn bipolar transistor 522 to fluctuate, and the piezoelectric vibrating member 13
An alternating drive voltage is applied to 0, and the operation of vibrating the piezoelectric vibrating member 130 to generate a counter electromotive voltage circulates,
If the drive voltage increases with each circulation, the oscillator circuit 500 oscillates.

When the remaining amount of ink in the ink storage means 100 is sufficient, the piezoelectric vibration member 130 is entirely immersed in the ink as shown in FIG. Since the ratio of the back electromotive force exceeds the amplification factor of the circuit, the oscillation circuit 500 does not oscillate, and np
n collector voltage V31 of the bipolar transistor 522
Maintains a constant level determined by the bias voltage and the impedances Z61 and Z62.

The remaining amount of ink decreases, and the piezoelectric vibrating member 13
When a part of 0 comes to protrude from the ink surface, the damping against vibration is weakened as the ink surface is lowered, and the ratio of the drive voltage / back electromotive force is lowered to fall below the amplification factor of the circuit. Then, the circuit oscillates at a frequency close to the natural frequency of the piezoelectric vibrating member 130.

At this time, the amplitude of the oscillation does not increase infinitely, but the ratio of the drive voltage / the counter electromotive voltage is changed to the ratio of the drive voltage / the counter electromotive voltage due to the amplitude dependency (non-linearity) of the drive voltage / the back electromotive voltage. Vibration continues at amplitudes where the amplification factors are equal.

This continuous amplitude becomes larger as the ratio of the initial drive voltage / counter electromotive voltage becomes larger. That is, as the ink surface decreases, the oscillation amplitude increases, and the peak value of the voltage waveform input from the emitter to the non-inverting input terminal of the operational amplifier 310 increases.

When the ink remaining amount decreases and the ink surface falls below a predetermined level, the peak value of the waveform of the collector voltage V31 is the operational amplifier 31 as shown in FIG. 10B.
0 voltage at the inverting input terminal E0 is exceeded. The collector voltage V31 passes from the output terminal 503 of the oscillation circuit to the input terminal 411 of the detection circuit and then to the operational amplifier 31 of the detection circuit 410.
The signal P2 is applied to the non-inverting input terminal of 0 and is periodically raised to the non-inverting input terminal of the AND gate 450 in the same manner as in the second embodiment.
The output QT of 0 is raised only once and then maintained in the state of falling to low, and the data of the Q terminal of the flip-flop 330 is raised from low to high to maintain this state.

Regarding the data of the Q terminal, when the input data QG of the control unit G of the switch means 356 rises to high, a current flows through the alarm generation circuit 350 to generate an alarm.

On the other hand, when the ink surface is higher than a predetermined level, the voltage applied to the non-inverting input terminal of the operational amplifier 310 is inverted as shown in FIG. Since the voltage E0 of the input terminal is not exceeded, the signal P2 is kept low without rising, the output QT of the AND gate 450 is also kept low, and finally the input data of the control unit of the switch means 356 is Since the low state is maintained and the high state is not raised, no current flows in the alarm generation circuit 350 and no alarm is generated.

Although the detection circuits of the respective embodiments described above all have a dedicated alarm generation circuit, the detection means in the present invention is not limited to this, and whether the ink surface level is higher than a predetermined level or not. There are many means for issuing an alarm based on this data, provided that it has storage means for storing low or high as high and low data. For example, there is a means for fetching this data into a microprocessor for controlling the operation of the printer, setting the printer in a non-printable state based on this data, and generating an error signal. Further, the alarm can be issued by transferring the data to a personal computer or the like connected to the printer and displaying a message on the display device.

Next, in the structure in which the signal pulse is generated when the level of the ink surface is lowered as in the third embodiment, an alarm is generated without using the storage means for storing the high and low data. You can also do it.

For example, in the circuit shown in FIG. 11, an alarm generating circuit 650 is constructed by connecting the anode A of the thyristor 610 to the high potential side of the DC power source via a load 620 such as a lamp and connecting the cathode K to ground. Then, the gate G of the thyristor 610 is connected to the output side of the diode 320 via the resistor R33. The structure before the diode 320 is the same as the circuit shown in FIG. 9 and used in the third embodiment, including the oscillation circuit 500.

Explaining the operation of this circuit, when the ink surface falls below a predetermined level, the signal pulse P2 is generated as described above and the thyristor 610 is generated.
Is added to the gate G of. The thyristor 610 is triggered by this and becomes conductive, and a current flows through the alarm generation circuit to generate an alarm.

Here, when the output voltage of the oscillation circuit 500 is sufficiently high, the operational amplifier 310 is not used,
The circuit is further simplified by connecting the input terminal 611 of the detection circuit 420 to the diode 320 as shown by the dotted line. In this case, the impedance Z61 of the oscillator circuit,
It is assumed that the resistance value of Z62 is appropriately selected and the amplification factor of the circuit is set so as to start oscillation when the ink surface becomes equal to or lower than a predetermined level.

If the signal pulse necessary for the determination is not sufficiently generated because the input to the detection circuit used in the present invention is weak, the comparator (for example, the comparator using the operational amplifier 310 in the embodiment) is used. By connecting an ordinary voltage amplifier using an operational amplifier or a bipolar transistor before (), the detection function of the device can be ensured.

[0074]

According to the present invention, in a printer using liquid ink, a small detection element is used without degrading the ink and the level of the ink remaining amount in the ink storage means such as an ink cartridge or an ink tank is accurately and surely ensured. It is possible to prevent the ink from running out.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a drive circuit according to a first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a detection circuit according to the first embodiment of the present invention.

FIG. 4 is a time chart showing the operation of the first embodiment of the present invention.

FIG. 5 is a perspective view showing an overall configuration of a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a detection circuit according to a second embodiment of the present invention.

FIG. 7 is a time chart showing the operation of the second embodiment of the present invention.

FIG. 8 is a perspective view showing an overall configuration of a third embodiment of the present invention.

FIG. 9 is a circuit diagram showing an oscillation circuit and a detection circuit according to a third embodiment of the present invention.

FIG. 10 is a time chart showing the operation of the third embodiment of the present invention.

FIG. 11 is a circuit diagram showing an oscillation circuit and a detection circuit according to another embodiment of the present invention.

[Explanation of symbols]

 100 Ink Storage Means 110 First Piezoelectric Member 120 Second Piezoelectric Member 130 Piezoelectric Vibration Member 200 Drive Circuit 300 Detection Circuit 350 Alarm Generation Circuit 352 Power Supply Section 354 Load 356 Switch Means 400 Detection Circuit 410 Detection Circuit 420 Detection Circuit 500 Oscillation Circuit 610 Thyristor 620 Load 650 Alarm generation circuit

Claims (6)

[Claims] 1. A first piezoelectric member and a second piezoelectric member facing each other, a drive circuit, and a detection circuit are provided, and a drive voltage is applied to the first piezoelectric member by the drive circuit to deform the first piezoelectric member. A pressure wave is generated in the ink interposed between the first piezoelectric member and the second piezoelectric member, the second piezoelectric member is deformed by the pressure wave to generate a counter electromotive voltage, and the counter electromotive voltage is detected by the detection circuit. Then, the remaining ink amount detecting device of the ink storing means is characterized by determining the level of the remaining ink amount. 2. An ink, comprising: a piezoelectric vibrating member; an oscillation circuit for vibrating the piezoelectric vibrating member; and a detection circuit for detecting an output of the oscillation circuit, wherein the detection circuit determines the level of the remaining ink amount. A device for detecting the remaining amount of ink in the storage means. 3. The ink remaining amount detecting device for an ink storage unit according to claim 1, wherein the detection circuit includes a comparison unit that compares an input voltage with a reference voltage. 4. The ink remaining amount detection of the ink storage unit according to claim 1 or 2, wherein the detection circuit includes a storage unit that stores data corresponding to the level of the ink remaining amount. apparatus. 5. The detection circuit includes storage means for storing data corresponding to the level of the remaining ink level, and controls the generation of an alarm by ANDing the output of the storage means and the enable signal. The ink remaining amount detecting device of the ink storing means according to claim 1. 6. The detection circuit includes an alarm generation circuit that controls conduction by a thyristor, and a trigger signal based on the output of the oscillation circuit is applied to the gate of the thyristor to make the thyristor conductive and to supply a current to the alarm generation circuit to issue an alarm. The ink remaining amount detecting device of the ink storing means according to claim 2, wherein the notification is made.