JPH0359833B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an inkjet printer that can perform high-quality output. [Prior Art] Conventionally, inkjet printers, for example, inkjet printers connected to computers, etc.
If the computer is not used, or if the nozzle remains inactive for a long time even when the printer is in use, the viscosity of the ink at the tip of the nozzle increases, resulting in a relatively long period of time. If printing is started after a printing non-operation state, at least initially there will be a problem that the ink will not be ejected properly, making it impossible to draw high-quality characters and figures. In an attempt to improve this, for example, in the prior art Japanese Patent Application Laid-Open No. 55-82660, if there is no ink ejection after a predetermined period of time has elapsed since ink ejection was interrupted, ink is ejected to prevent clogging. Techniques aimed at preventing this have been disclosed. However, there is a problem in that no consideration has yet been given to how to ensure ink ejection to prevent this. [Objective] In view of the above points, an object of the present invention is to provide a method for printing a printer when it is determined that any one of a plurality of ejection ports is in a non-driving state for a predetermined period of time, and when the printer is in a non-printing state. It is an object of the present invention to provide an inkjet printer in which, when it is determined that the inkjet printer has recovered, ink is ejected from all of the plurality of ink ejection ports to perform recovery processing very efficiently and reliably. [Example] Hereinafter, the present invention will be explained in detail based on the drawings. FIG. 1 shows an embodiment of the control circuit for the inkjet printer of the present invention. In the figure, the reference numeral 1 is a motor for moving the carriage, and the motor is connected between the power supply voltage VP and the drive output of the drive amplifier 24. It is connected to the. A motor drive signal M is connected to the input of the drive amplifier 24, and this motor drive signal M is input to the input terminal I4 of the voltage comparator 30. The output S of the voltage comparator 30 is input to OR gates 4, 5, and 6 whose other inputs receive piezoelectric element drive signals PX1, PX2, and PX3, respectively, and the outputs of the OR gates 4, 5, and 6 are the signals. Pi1,
Drive amplifiers 21 and 2 as Pi2 and Pi3 respectively
2 and 23. The outputs of the drive amplifiers 21, 22, 23 are connected to the piezoelectric elements 7, whose other terminals are connected to the power supply voltage VP.
8 and 9 via signals P1, P2, and P3. These piezoelectric elements 7, 8, and 9 are for ejecting ink of different colors, and when these are driven, ink is ejected from nozzles (not shown). The output signals P1, P2, P3 of the drive amplifiers 21, 22, 23 are connected to diodes D1, D2, D3.
are inputted to input terminals I1, I2, and I3 of the voltage comparator 30 via. The input terminal of this voltage comparator 30
Resistors RT1, RT2, RT3 and capacitors C1, C2, C3 are further connected to I1, I2, and I3, and one side of resistors RT1, RT2, and RT3 is connected to the power supply voltage.
VP is connected, and capacitors C1, C2,
One side of C3 is grounded to 0 potential. Resistors RT1, RT2, RT3 and capacitors C1, C
2 and C3 each form a kind of time constant circuit,
Output signals P1, P of drive amplifiers 21, 22, 23
2. When P3 becomes low level, diode D1,
Capacitors C1, C2, C3 via D2, D3
is discharged, the input voltages v1, v2, v3 of the input terminals I1, I2, I3 of the voltage comparator 30 become low level, and when P1, P2, P3 become high level, the resistors RT1, RT2, RT3 are discharged by the power supply voltage VP. The capacitors C1, C2, and C3 are charged over a certain period of time through the capacitors C1, C2, and C3, so that v1, v2, and v3 are gradually brought to a high level. A timing switch 13 is connected to the power supply voltage VP, and is turned ON/OFF in synchronization with carriage movement via a relay solenoid (not shown) to generate a timing pulse TP. This pulse is used by another control system to drive the piezoelectric elements 7, 8, and 9 via signals PX1, PX2, and PX3 to perform desired printing. The circuit shown in FIG. 2 is the drive amplifier 21 of FIG.
22, 23, and 24, including a transistor Q, a base input resistance RI, and a bias resistance.
When a high level is applied to the input I, a base current flows through the resistor RI, the transistor Q becomes conductive, and the output O becomes a low level. Conversely, when the input I is at a low level, the base current of the transistor Q does not flow, so the output O is at a high level. FIG. 3 shows an embodiment of the voltage comparator 30 shown in FIG.
01, D102, and D103 are grounded, and the cathodes of the diodes D101, D102, and D103 are connected to the base of the transistor Q101 and the collector of the transistor Q103 via the Zener diode ZD and the resistor R101. A resistor R102 is connected between the base of the transistor Q101 and the collector of the transistor Q103 and ground (0 potential). The emitter of transistor Q101 is connected to 0 potential, and its collector is connected to the base of transistor Q102 via resistor R103. A resistor R10 is connected to the base of the transistor Q102.
4, the power supply voltage VP is directly applied to the collector. The emitter of the transistor Q102 is connected to the output terminal S, and is also connected to the 0 potential together with the emitter of the transistor Q101 via a resistor R107. The emitter of transistor Q103 is directly grounded to 0 potential, and the base is grounded to 0 potential via resistor R106 and connected to the input terminal of motor drive signal M via resistor R105. Transistor Q103 is an npn transistor,
When the input I4 becomes high, that is, the motor drive signal M becomes high, the base current flows through the base resistor R105, turning on the npn transistor Q.
Transistor Q with the base potential of 101 low
101 is turned off. In other words, this is to prevent the transistor Q101 from turning on under any other conditions while the motor drive signal M is high, that is, during printing, and to ensure that idle ejection of ink occurs only in non-printing conditions, as will be described later. It is meant to be. Voltages v1, v2, v3 are applied to input terminals I1, I2, I3, and when these voltages v1, v2, v3 reach a predetermined reference voltage (hereinafter referred to as vS), the corresponding diodes D1, D2, A current sequentially flows from the Zener diode ZD, the resistor R101, and the base of the npn transistor Q101 to 0 potential through D3, and the npn transistor Q101 is turned on. However, here, this transistor Q1
The reference voltage vS that turns ON 01 is based on the following equation. vS=VDf+VBE+ZE+VBE・(R101+R102)/R102...(1) However, VDf: Diode D101, D10
2, forward voltage of D103, ZE: Zener voltage of Zener diode ZD, VED: base-emitter voltage of transistor Q101. When transistor Q101 turns on, the resistor
The base current of transistor Q102 flows through R103, turning on transistor Q102,
A high level voltage across the load resistor R107 appears at the output S of the voltage comparator 30. The above description of the voltage comparator 30 with reference to FIG. 3 can be summarized as follows.
0 means that when the motor drive signal M is at low level, that is, in the non-printing state, if any one of the input voltages v1, v2, and v3 of the input terminals I1, I2, and I3 exceeds the reference voltage vS, the output S will be It is configured to be at a high level. The operation of the above configuration will be explained in detail below with reference to the timing chart shown in FIG. However, in FIG. 4, the symbols attached to each waveform represent each signal or the input or output signal of each terminal in FIGS. 1 to 3, respectively. First, a control system (not shown) sets the motor drive signal M to a high level, causes current to flow through the motor, and drives the motor to move the carriage. Based on the timing signal TP generated along with this, a control system (not shown) sends signals PX1, PX2, PX3 to obtain printing.
to a high level as appropriate. Since the drive amplifiers 21, 22, and 23 are configured as described above, the output signal P is output according to the input signals Pi1, Pi2, and Pi3 via the OR gates 4, 5, and 6.
1, P2, and P3 become low level. As a result, the corresponding capacitors C1, C2, C3 are discharged via the diodes D1, D2, D3, and the input voltages v1, v2, v3 of the input terminals I1, I2, I3 of the voltage comparator 30 correspond to the discharge of each capacitor. and becomes low level. Here, the low level of the signals P1, P2, P3 corresponding to the signals PX1, PX2, PX3 means the drive amplifiers 21, 22,
A current path from the power supply voltage VP to the piezoelectric elements 7, 8, 9 to the transistor Q is formed through the transistor Q of 23, and the voltage elements 7, 8, 9 correspond to the signals PX1, PX2, PX3. Needless to say, the ink is ejected from the nozzles corresponding to the piezoelectric elements 7, 8, and 9, and desired printing is performed. When the piezoelectric element drive signals PX1, PX2, and PX3 are deactivated, the signals P1, P2, and P3 correspondingly return to high level, and the capacitors C1, C2, and C3
are blocked by diodes D1, D2, D3,
The power supply voltage VP gradually charges the resistors RT1, RT2, and RT3 over a period of time t according to a predetermined time constant.

[Formula] ...(2) (where n=1, 2, 3) Voltages v1, v2, and v3 corresponding to the voltages are generated at the input terminals I1, I2, and I3 of the voltage comparator 30. As printing proceeds further and the piezoelectric element 7 is not driven by the drive signal PX1 after the first printing as shown in the timing chart of FIG. 4, the capacitor C1 continues to be charged, and the input terminal I1 of the voltage comparator 30 The applied voltage v1 increases and finally reaches the reference voltage vS after the elapse of time t. However, here, the time t is determined by the following equation. t=-Cn・RTn・log(1+vS/VP)...(3) In this embodiment, t=3 min is set. When the motor 1 is not being driven, that is, in a non-printing state, if any one of the voltages v1, v2, and v3 reaches the reference voltage vS, the voltage comparator 30
The output S of becomes high level, and the OR gate 4,
All drive amplifiers 21, 22, 2 via 5, 6
A high level is sent to 3, and all piezoelectric elements 7,
8 and 9 are driven to perform idle ejection. By this driving, the capacitors C1, C2, and C3 are discharged in the procedure described above, and the input voltages v1, v2, and v3 at the input terminals 30 of the voltage comparator 30 are returned to their initial states. In the embodiments described above, the number of voltage elements, that is, ink ejecting nozzles, is limited to three, but it goes without saying that the present invention can be similarly implemented with any number of voltage elements. Further, in the above embodiments, the ink jet nozzle is driven by a piezoelectric element, but it is of course possible to use other driving methods. By adopting the configuration of the present invention detailed above, if even one of the plurality of ink ejection nozzles is not driven for a predetermined period of time, all the ejection nozzles are emptied at the same time by the control of the detection circuit that detects this. Because of the ejection structure, it is possible to obtain an on-demand type inkjet printer with a plurality of nozzles, which is equipped with a dry ejection mechanism that prevents ink from drying, with a simple and inexpensive structure. Note that the present invention may be achieved in one device, or may be achieved in a system consisting of a plurality of devices. Further, the printer section and the data supply source may be integrated or separate, or the present invention may be achieved by supplying a program to the device or system. [Effect] As detailed above, according to the present invention, even if it is determined that any one of the plurality of ejection ports is in a non-driving state for a predetermined period of time, if the printing process is in progress, the recovery is possible. If no processing is performed and it is determined that one of the plurality of ejection ports is in a non-driving state for a predetermined period of time, and the printer is determined to be in a non-printing state, the plurality of ejection ports Ink is ejected from all of the ink ejection ports to ensure recovery processing, and there is no need to immediately interrupt the printing process in response to the determination, so printing efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of the control circuit of the present invention, FIGS. 2 and 3 are detailed circuit diagrams of a part of the circuit of FIG. 1, and FIG. FIG. 3 is a timing chart explaining a control procedure. 1... Drive motor, 4, 5, 6... OR gate, 7, 8, 9... Piezoelectric element, 21, 22, 23
...Drive amplifier, 30...Voltage comparator.

Claims (1)

[Scope of Claims] 1. An inkjet printer capable of printing by selectively driving a plurality of ink ejection ports mounted on a carriage to eject ink when necessary for printing, comprising: Detection means for detecting that any one of the plurality of ejection ports is in a non-driving state for a predetermined period of time, and a determination means for determining whether the printer is in a non-printing state due to the carriage being in a stopped state. , when the detection means determines that any one of the plurality of ejection ports is in a non-driving state for a predetermined period of time, and the determination means determines that the printer is not in a non-printing state. If it is determined that there is no recovery process for all of the plurality of ink ejection ports, the detection means determines whether any one of the plurality of ink ejection ports remains in a non-driving state for a predetermined period of time. If it is determined that there is, and the determination means determines that the printer is in a non-printing state, for all of the plurality of ink ejection ports,
An inkjet printer characterized in that it has a control means for performing recovery processing. 2. The inkjet printer according to claim 1, wherein the inkjet printer discharges the ink by the action of a piezoelectric element. 3. The inkjet printer according to claim 1, wherein the inkjet printer has a plurality of nozzles that eject ink of a plurality of colors. 4. The inkjet printer according to claim 1, wherein the determination by the determination means is based on a drive signal of a motor that drives the carriage.