JPH0930005A - Ink residual amount detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the residual amt. of ink only by applying one pulse voltage to an electrode and to directly subjecting detected voltage to digital processing without generating the electrolysis of ink and exerting no adverse effect on the characteristics of ink and requiring an analogue part such as an expensive A/D converter. SOLUTION: Only one pulse voltage is applied across a pair of electrodes 24, 25 provided in the state capable of coming into contact with the ink in an ink cartridge by a pulse generation part 31 and a flip-flop 32 latches the voltage appearing corresponding to the impedance between the electrodes 24, 25 at the time of the application of pulse voltage in this pulse voltage applying timing and detects the residual amt. of ink based on this latch output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink remaining amount detecting device for detecting the amount of ink remaining in an ink cartridge filled with ink supplied to a print head.

[0002]

2. Description of the Related Art Conventionally, a print recording device, for example, a device for detecting the remaining amount of ink in an ink cartridge or an ink tank used in an ink jet printer or the like for ejecting ink to print and record on a recording medium, Various detection methods are known, and among them, the device that electrically detects the remaining amount of ink is a device that performs control such as issuing a warning when the remaining amount is low or stopping printing. It is advantageous. To electrically detect the remaining amount of ink, a method of installing electrodes in the ink cartridge is adopted. Since the impedance between the installed electrodes changes depending on the presence or absence of ink, the remaining ink amount can be detected by measuring the amount of change in impedance.

However, in the above method, when a direct current is passed between the electrodes, electrolysis occurs, gas is generated, and the characteristics of the ink itself are deteriorated. Therefore, in order to solve this problem, there is also known a technique of flowing an AC pulse current instead of a DC current between the electrodes. In such a technique, by converting the voltage depending on the impedance between the electrodes to which an alternating voltage is applied into a direct current, an expensive high-speed A / D
There has been proposed a device that can perform digital processing of detection output by using a low-speed A / D converter without using a converter and enables highly accurate detection (for example, see Japanese Patent Laid-Open No. 5-330079). ).

[0004]

However, in the conventional device as described above, only when a signal for detecting the remaining ink amount is given to the electrodes from the pulse generator for applying the AC voltage. A detection signal can be taken out, which cannot be detected by applying one pulse, and detection can be performed only by continuously applying pulses. Therefore, electrolysis of the ink still occurs, which adversely affects its characteristics. Further, since the AC voltage appearing between the electrodes is converted to DC, the detection signal can be digitally processed only through analog parts such as an A / D converter.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to detect the ink remaining amount only by applying one pulse voltage to the electrodes, and the ink is not electrolyzed and the ink is not electrolyzed. Without adversely affecting the characteristics of
Another object of the present invention is to provide an inexpensive ink remaining amount detecting device which does not require any analog parts such as an A / D converter and can directly digitally process the AC voltage detected between the electrodes. .

[0006]

In order to achieve the above object, an ink remaining amount detecting device according to a first aspect of the invention is an ink residual amount accumulated in an ink cartridge filled with ink to be supplied to a print head. In an ink remaining amount detecting device that detects the amount, a pair of electrodes is provided in an ink cartridge so as to be able to come into contact with the ink inside, and only one pulse voltage is applied between the electrodes when the remaining amount is detected. The pulse generating means and the voltage holding means for latching the voltage appearing according to the impedance between the electrodes at the time of applying the pulse voltage at the pulse voltage applying timing by the pulse generating means are provided, and based on the latch output from the voltage holding means. The amount of ink remaining is detected. In the above structure, only one pulse of the pulse voltage is applied by the pulse generating means between the pair of electrodes provided so as to be in contact with the ink inside the ink cartridge, and the voltage holding means applies the pulse voltage at the pulse voltage application timing. When a voltage is applied, the voltage appearing according to the impedance between the electrodes can be latched, the remaining ink amount can be detected based on this latch output, and the AC voltage appearing between the electrodes can be directly digitally processed.

According to a second aspect of the present invention, in the ink remaining amount detecting device according to the first aspect, the voltage holding means has a flip-flop circuit, and the flip-flop circuit has a voltage appearing between the electrodes. The AC component voltage and the pulse voltage from the pulse generating means are input. In the above configuration, since the AC component voltage appearing between the electrodes when the pulse voltage is applied between the electrodes can be held by the flip-flop circuit, the impedance between the electrodes can be reliably detected only by the pulse voltage of one pulse. The remaining amount can be detected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the ink remaining amount detecting device of the present invention is applied to an ink jet printer will be described below with reference to the drawings. FIG. 1 is a perspective view of an inkjet printer. In FIG. 1, a manual paper feeding unit 3 is provided at the front of the main body frame 2 of the inkjet printer 1.
On the rear side of the manual paper feeding unit 3, on the upper part of the main body frame 2, is placed a subframe 4 having a carriage 9 for mounting an inkjet print head 10 and a purging device 18, etc., which will be described later. Has been done. A paper feed cassette 5 for storing a plurality of printing papers is detachably attached to the upper rear part of the sub-frame 4, and a paper discharge tray (not shown) for discharging the paper after printing is provided in the paper feed cassette 5 It is attached to the front side opposite to.

FIG. 2 is a perspective view showing the sub-frame 4, the print head 10 built in the sub-frame 4, the purging device 18, the paper feeding mechanism 19 and the like. In FIG. 2, a cylindrical platen roller 6 is arranged behind the sub-frame 4 inside. The platen roller 6 conveys the print paper supplied from the paper feed cassette 5 or the manual paper feed unit 3 while facing the print head 10, and forms a part of the paper feed mechanism 19. A pressure roller 8 is provided above the platen roller 6 to bring the printing paper into close contact with the platen roller 6. The platen roller 6 is driven via a platen gear 7 by a paper feed motor (not shown). The platen gear 7 includes one sheet of printing paper from the paper feeding cassette 5,
The drive is also transmitted to a sheet feeding gear train for feeding the platen roller 6.

Further, a carriage 9 is provided in front of the platen roller 6. The carriage 9 has a print head 10 mounted thereon and is movable along a carriage shaft 11 provided in parallel with the platen roller 6. The carriage 9 is driven by a carriage motor 12 via a belt 13. A purge device 18 is provided on the side of the platen roller 6. Since the ink jet type print head 10 may cause ejection failure due to the generation of air bubbles inside or the deposition of ink droplets on the ejection surface during its use, this is solved and good ejection is achieved. There is a purging device 18 to restore the condition. The purging device 18 is provided with a cap 15 at its tip, and when the print head 10 is covered with the cap 15, a negative pressure is generated by a pump to suck the defective ink inside the print head 10. The print head 10 is recovered. The print head 10 is provided integrally with the head unit 20, and an ink cartridge 22 (also called an ink tank) that supplies ink to the print head 10 is detachably mounted on the carriage 9 together with the head unit 20. It

FIG. 3 is a sectional view showing a state in which the ink cartridge 22 is held by the holder portion of the print head unit 20. The ink cartridge 22 has a pair of electrodes 2 which are in contact with the ink 23 in the cartridge in order to detect the amount of ink remaining in the ink cartridge 22.
4, 25 are provided so as to face the outside of the cartridge. The holder portion of the head unit 20 is provided with electrode terminals 26 and 27 that are electrically connected to the electrodes 24 and 25 when the ink cartridge 22 is held. The electrode terminals 26 and 27 are electrically connected to an ink remaining amount detection circuit provided in a control unit on the apparatus main body side described later. When the head unit 20 is mounted on the carriage 9, the connection terminals (not shown) provided on the facing surfaces of the two come into contact with each other so that a control signal can be transmitted from the control section on the apparatus main body side to the print head. The electrical connection described above is performed in the same manner. The electrode terminal 27 is on the ground side.

FIG. 4 is a circuit diagram for detecting the amount of ink remaining in the ink cartridge 22.
The detection circuit 30 uses a pulse generator (pulse generator) 31 that applies a pulse voltage of only one pulse between the electrodes 24 and 25 when detecting the remaining amount, and a pulse voltage application timing by the pulse generator 31. D flip-flop (voltage holding means) 32 for latching a voltage that appears according to the impedance between electrodes 24 and 25 when a pulse voltage is applied
And That is, the D flip-flop 32
Indicates the pulse voltage generated by the pulse generator 31 as the clock CL.
As an input, the voltage appearing between the electrodes 24 and 25 when a pulse voltage is applied is input, and the voltage is held at the output end.

In the detection circuit 30, the pulse output voltage a from the pulse generator 31 is applied between the electrodes 24 and 25 via the DC component cutting capacitor C1 and the resistor R1, and the impedance between the electrodes 24 and 25 is increased. The voltage b appears according to This voltage b is output as a voltage c through the noise removing buffer 33 from the parallel connection circuit of the diode D1 and the resistor R2 via the capacitor C2 for cutting the direct current component. This voltage c becomes the input voltage of the D flip-flop 32, this input voltage is latched at the clock input timing, and the voltage d is output to the output terminal of the D flip-flop 32. It should be noted that the pulse generator 31 may output one pulse at any time when the remaining ink amount needs to be detected.

FIG. 5 shows the voltage signal waveforms of the respective parts when there is no ink remaining in the detection circuit 30 which operates in this way and when there is ink. When there is no ink remaining in the ink cartridge 22, the impedance between the electrodes 24 and 25 is high. Therefore, when the pulse output voltage a is applied, the voltage b appears between the electrodes 24 and 25, and the resulting voltage c Is input to the D flip-flop 32, which is latched, and the output voltage d rises to H (or remains at H). On the other hand, when there is ink remaining in the ink cartridge 22, the impedance between the electrodes 24 and 25 is low, so that when the pulse output voltage a is applied, the electrodes 24 and 2
The voltage b hardly appears between 5 and therefore, the output voltage d of the D flip-flop 32 remains L (or falls to L). In this way, depending on the presence or absence of ink,
Since the output voltage d changes, the remaining ink amount can be detected based on this change.

According to this embodiment, since the pulse voltage can be applied between the electrodes by only one pulse to detect the remaining ink amount, the remaining ink amount can be detected. Electrolysis of ink is reduced as compared with a conventional device that applies a pulse to reduce the problem of deterioration of ink characteristics. In addition, since the detection signal is an AC voltage that appears between the electrodes when only one pulse is applied, it is possible to directly perform digital processing, eliminating the need for expensive analog components such as an A / D converter, and making an inexpensive device. Can be provided.

The present invention is not limited to the configuration of the embodiment described above, and various modifications are possible. For example, in the above embodiment, the D flip-flop 32 is used to latch the voltage appearing between the electrodes 24 and 25 when the pulse voltage is applied, but the present invention is not limited to this, and it has the function of latching the detection voltage at a predetermined timing. A microprocessor (CPU) or the like can also be used.

[0017]

As described above, according to the ink remaining amount detecting apparatus of the first aspect of the invention, the pulse voltage of one pulse is applied to the electrodes provided on the ink cartridge, and the pulse voltage is applied between the electrodes. Since the voltage that appears is latched and the remaining ink amount is detected based on this latched output voltage, electrolysis of the ink does not occur and the characteristics of the ink are not adversely affected. Further, since the AC voltage appearing between the electrodes can be directly digitally processed, it does not require an expensive analog component such as an expensive A / D converter as in the conventional case, and the cost is low. According to the ink remaining amount detecting device of the second aspect of the invention, in addition to the above effect, the AC component voltage appearing between the electrodes when the pulse voltage of one pulse is applied is held by the flip-flop circuit. The impedance between the electrodes can be reliably detected with a simple configuration, and the ink remaining amount can be detected.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a sub-frame portion of the inkjet printer.

FIG. 3 is a cross-sectional view showing a state in which the ink cartridge is held by the holder portion of the print head unit.

FIG. 4 is a circuit diagram for detecting the amount of ink remaining in an ink cartridge.

FIG. 5 is a diagram showing voltage signal waveforms of respective portions of the circuit when ink is absent and when ink is present.

[Explanation of symbols]

 10 Print Head 22 Ink Cartridge 24, 25 Electrode 30 Detection Circuit 31 Pulse Generation Section (Pulse Generation Means) 32 D Flip-Flop (Voltage Holding Means)

Claims (2)

[Claims] 1. An ink remaining amount detecting device for detecting an ink remaining amount stored in an ink cartridge filled with ink to be supplied to a print head, wherein the ink cartridge can come into contact with ink inside. A pair of electrodes is provided in the state, pulse generating means for applying only one pulse voltage between the electrodes when detecting the remaining amount, and pulse voltage applying timing by the pulse generating means, the electrodes when applying the pulse voltage. An ink remaining amount detecting device, comprising: a voltage holding unit that latches a voltage that appears according to an impedance between them, and detects the ink remaining amount based on a latch output from the voltage holding unit. 2. The voltage holding means has a flip-flop circuit, and the flip-flop circuit receives an AC component voltage of a voltage appearing between the electrodes and a pulse voltage from the pulse generating means as inputs. The remaining ink amount detecting device according to claim 1.