JPH11179933A - INK JET PRINTING APPARATUS AND INK PRESENCE DETECTION METHOD - Google Patents

Abstract

(57) [Problem] To provide an ink jet printing apparatus and an ink presence / absence detection method capable of automatically detecting presence / absence of ink and discharge failure with a simple configuration. SOLUTION: A heater resistor 41 of the recording head is adjacent to the ink via a thin insulating film to transfer heat to the ink. Therefore, the heater resistor 41 and the ink form a capacitor. Therefore, the ink detection is performed, for example, by applying a voltage to the common terminal 1 and determining whether this voltage appears on the common terminal 2 side via the above-described capacitor. If the ink cannot be detected by this operation, a process for recovering the ejection failure is performed, and after this process, the ink is detected again by the above-described operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus,
In particular, an ink jet printing apparatus equipped with a recording head having a plurality of recording elements (also referred to as an ink jet printer)
And a method for detecting the presence or absence of ink.

[0002]

2. Description of the Related Art Ink-jet printers have attracted attention as printers capable of quiet and high-speed printing in a low-cost configuration, and various performances have been improved. In particular, in recent years, it has been remarkably developed as a color printer capable of low-cost, high-quality color printing.

[0003]

However, in an ink jet printer, there is a possibility that an ink droplet ejection defect may occur due to bubbles or the like generated in a recording head.
For this reason, an ink jet printer is often provided with an ejection recovery means by a method such as sucking ink from a recording head. However, since it is difficult to automatically detect a discharge failure, there is a problem that printing is continued in a discharge failure state unless a user finds a discharge failure and performs a recovery operation.

[0004] Further, the ink jet printer has a problem that it is difficult to detect the remaining amount of ink. As a method of detecting the remaining amount of ink, there are a method of detecting ink ejection with an optical sensor and a method of detecting the internal pressure of an ink tank with a pressure sensor, but any method requires an expensive sensor. . In particular, since a color printer is provided with ink tanks for three or four colors, a sensor for detecting the remaining amount is often required by the number of ink tanks. Therefore, an inexpensive printer does not include the ink remaining amount detecting means, and if the user does not notice that the ink has run out, there is a problem in that printing is continued with the ink running out.

The present invention has been made under such circumstances, and a first object of the present invention is to automatically detect the presence / absence of ink and defective ejection with a simple configuration. A second object of the present invention is to provide an ink remaining amount detecting means that does not require expensive sensors, and in particular, to provide a remaining ink amount detecting means suitable for a color inkjet printer.

[0006]

In order to achieve the above object, according to the present invention, an ink jet printing apparatus is provided with the following (1).
To (7).

(1) A recording head having a plurality of recording elements for ejecting ink droplets, driving means for selectively driving each recording element of the recording head, and a plurality of connecting means for connecting the driving means to the recording head. A signal line, and changing a voltage of a predetermined first signal line in the signal line without driving the recording head, and synchronizing with a change in the voltage, a predetermined second signal line in the signal line. An ink jet printing apparatus comprising: an ink detecting unit that detects a voltage of the ink and detects the presence or absence of the ink based on the voltage.

(2) The ink jet printing apparatus according to (1), further comprising: recovery means for recovering a discharge failure of the recording head; and means for operating the recovery means when the ink detection means detects the absence of ink. Inkjet printing equipment.

(3) In the ink jet printing apparatus according to the above (1), a display means for displaying that the recording head is out of ink, and when the ink detecting means detects the absence of ink, the display means displays a message indicating that the ink has run out. And an inkjet printing apparatus.

(4) A recording head having a plurality of recording elements for ejecting ink droplets, driving means for selectively driving each recording element of the recording head, and a plurality of connecting means for connecting the driving means and the recording head. A signal line, and changing a voltage of a predetermined first signal line in the signal line without driving the recording head, and synchronizing with a change in the voltage, a predetermined second signal line in the signal line. Ink detecting means for detecting the presence or absence of ink based on the voltage, recovery means for recovering ejection failure of the recording head, display means for displaying that the recording head is out of ink, and the ink detecting means Control means for operating the recovery means and then operating the ink detection means when detecting the absence of ink in the above, and for displaying the out of ink on the display means when detecting the absence of ink The ink jet printing apparatus comprising a.

(5) The above (1), (2), (3),
(4) The inkjet printing apparatus according to any one of (4), further including a recording head capable of printing a plurality of colors, and including the first signal line and the second signal line for each color.

(6) The above (1), (2), (3),
(4) The inkjet printing apparatus according to any one of (5) and (5), wherein the plurality of signal lines are connected to heater resistors of the plurality of recording elements.

(7) A method for detecting the presence or absence of ink in a recording head having a plurality of recording elements, wherein a driving element for driving the recording element is used as an electrode, and a change in the capacity of a capacitor using the ink as a dielectric is used as the ink. A method for detecting the presence or absence of ink for detecting the presence or absence of ink.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples of an ink jet printing apparatus. Although the embodiment is of the electric / heat exchange type (bubble jet type), the present invention is not limited to this.
The present invention can be similarly implemented in an appropriate printing device such as an electromechanical conversion system (piezoelectric type). Further, the present invention can be implemented in the form of a method for detecting the presence or absence of ink.

[0015]

FIG. 1 is a block diagram showing the configuration of a control circuit of a "printing apparatus" according to a first embodiment. FIG.
1 is a CPU, 2 is a ROM, 3 is a RAM, 4 is an interface, 5 is a printer control IC, 6
Denotes a recording head, 7 denotes a head driver, 8 denotes a printer unit, 9 denotes a motor driver, and 10 denotes an operation panel.

The CPU 1 analyzes commands and data received from a host computer (not shown), creates bit image data corresponding to the final recorded contents, and controls the entire printing apparatus. The ROM 2 stores a program for controlling the CPU 1.
The RAM 3 temporarily stores data received from the interface 4 and stores recording data obtained by analyzing the received data by the CPU 1. The interface 4 is a connection unit with a host computer. The printer control IC 5 is connected to the bus line of the CPU 1 and controls the RAM 3, the interface 4, and the recording head 6 based on a command from the CPU 1. The recording head 6
It is a 64-nozzle bubble jet system, which is integrated with an ink tank and can be replaced by a user. The head driver 7 converts a head control signal output from the printer control IC 5 into a voltage / current level at which the recording head can be driven. The head driver 7 converts the level of the ink detection signal received from the recording head 6 and outputs the signal to the CPU 1. The printer unit 8 is a mechanism unit that performs a recording operation, and includes a carriage system that scans a recording head using a carriage motor as a driving source, a paper feeding system that conveys recording paper using a paper feeding motor as a driving source, and sucks ink from the front surface of the head. And a recovery system for performing a head recovery operation, a carriage position detection sensor, a paper detection sensor, and the like. A paper feed motor is also used as a drive source of the suction pump of the recovery system. The motor driver 9 includes a carriage motor driver and a paper feed motor driver. The operation panel 10 includes a switch and a display lamp.

FIG. 2 is a circuit diagram for explaining the electrical configuration of the recording head. In FIG. 2, reference numeral 41 denotes a heater resistor, and reference numeral 42 denotes a diode, both of which are formed on a chip board of a recording head. There are a total of 64 heater resistors 41, which are arranged at each nozzle of the print head. Similarly, there are 64 diodes 42.

One end of the heater resistor 41 is connected to each of the current inflow terminals CM1 to CM8 after being connected together by eight. Hereinafter, the CM1 to CM8 terminals are referred to as common terminals. The other end of the heater resistor 41 is connected to a diode 4
2 is connected to the anode side. The cathode side of the diode 42 is connected every eight in a form orthogonal to the connection on the common terminal side, and is connected to the current outflow terminals SG1 to SG8. Hereinafter, the SG1 to SG8 terminals are referred to as segment terminals.

The recording head 6 has common terminals CM1 to CM8.
It is driven by passing a current from the side to the segment terminals SG1 to SG8. Driving is performed for each common terminal. First, turn on the driver connected to the CM1 terminal
By doing so, it becomes possible to energize the eight heater resistors connected to the CM1 terminal. At this time, the heater resistance to be energized is selected by controlling ON / OFF of the driver on the segment side. The heater resistor connected to the turned-on segment terminal generates heat by energization and causes the nearby ink to foam. An ink droplet is ejected from the nozzle by the pressure of this bubbling. Hereinafter, CM2 to CM
By sequentially turning on the common-side driver up to 8, it becomes possible to energize all the heater resistors.

FIG. 3 is a block diagram showing a circuit configuration of the head driver 7. In FIG. 3, reference numeral 51 denotes a pre-driver, 52 denotes a common driver, and 53 denotes a segment driver. The printer control IC 5 (see FIG. 1) outputs common control signals COM1 to COM8 and segment control signals SEG1 to SEG8. The pre-driver 51 is
The common control signals COM1 to COM8 output from the printer control IC 5 are converted to a level at which the common driver 52 can be driven. The common driver 52 is a source type driver, and supplies current to the common terminals CM1 to CM8 of the recording head 6. The segment driver 53 is a source type driver, and draws current from the segment terminals SG1 to SG8 of the recording head 6 according to the segment control signals SEG1 to SEG8 output from the printer control IC5.

In order to detect ink, the recording head 6
The signal ID obtained by dividing the common terminal CM2 with a resistor is
1 AD conversion terminal (see FIG. 1).

FIG. 4 is a timing chart of a head control signal during a printing operation. In FIG. 4, the common control signals COM1 to COM8 are sequentially driven, and the segment control signals SEG1 to SEG1 are turned on while each of the common control signals is ON.
The SEG 8 is selectively turned on in accordance with the recording data.
The segment control signal is first applied to the odd segment SEG1,
3, 5, 7 are driven, followed by the even segment SEG
2, 4, 6, and 8 are driven. At the time of driving the next head, the even segments SEG2, 4, 6, 8 are driven first, and then the odd segments SEG1, 3, 5, 7 are driven. By driving the segment control signal twice, the current flowing to the common terminals CM1 to CM8 is halved as compared with the case where all the segments are driven at the same time. Therefore, the allowable current capacity of the common driver 52 is reduced to reduce the circuit size. And lower prices are possible. Further, since the number of simultaneously driven nozzles is reduced by half, the vibration of ink in the head caused by the ejection of ink droplets is reduced. Ink vibration prevents uniform ejection of ink droplets and causes deterioration of print quality. Therefore, reduction of ink vibration contributes to improvement of print quality. Further, the driving conditions of the odd and even segments are made equal by alternately driving the odd and even segments first.

The heater resistor 41 of the recording head 6 is adjacent to the ink via a thin insulating film to transfer heat to the ink. Therefore, the heater resistor 41 and the ink form a capacitor. In addition, since the ink contains an electrolyte, it can carry charges. Therefore, when the nozzle portion of the recording head 6 is filled with ink, each of the heater resistors 41 is capacitively connected.

FIG. 5 is an explanatory diagram of ink detection. In FIG. 5, by driving the common control signal COM1, the potential of the common terminal CM1 increases. Common terminal C
Since the voltage change of M1 is propagated to another common terminal, for example, CM2 by ink, the voltage of the common terminal CM2 changes depending on whether there is ink in the nozzle portion. That is, when there is ink, the voltage is high, and when there is no ink, the voltage is low. The voltage of the common terminal CM2 is divided into a logic level signal ID by a resistor, and is input to the AD converter terminal of the CPU1. Therefore, at time t
The presence or absence of ink can be detected by reading the potential of the signal ID at step A with an AD converter.

FIG. 6 shows a flowchart of the operation for detecting the remaining amount of ink.

In step 201, the signal operation shown in the timing chart of FIG. 5 is performed to detect the presence or absence of ink in the nozzle portion. In step 202, if the voltage level of the ID read by the AD converter of the CPU 1 is equal to or more than a predetermined value, it is determined that there is ink, and in step 203, the operation returns to the normal printing operation. In step 202, if the voltage level of the ID read by the AD converter of the CPU 1 is equal to or less than a predetermined value, there is no ink in the nozzle portion. Therefore, in step 204, the suction pump is operated to perform the head recovery operation. Step 2
In step 05, ink detection is performed again in the same manner as in step 201. If it is determined in step 206 that there is ink,
Return to step 203. If there is no ink in step 206, it is determined that the ink tank is empty, an out-of-ink display is displayed on the operation panel, an error status is returned to the host computer, and the printing operation is interrupted.

As described above, by utilizing the change in the capacity between the heater resistances due to the presence or absence of ink in the nozzle portion of the recording head, it is possible to determine the presence or absence of ink in the nozzle portion in an extremely inexpensive configuration having only a voltage dividing resistor. Detection is possible,
Discharge failure can be detected and automatically recovered. Further, the detection of the presence or absence of ink in the nozzle portion can be used as the detection of running out of ink in the ink tank.

For detecting the voltage level, an AD built in the CPU is used.
The use of the converter can suppress an increase in cost.

(Embodiment 2) FIG. 7 is a block diagram showing the main configuration of a "printing apparatus" according to Embodiment 2. The basic configuration is the same as that of FIG.
PU1 is connected by three ink detection signals ID1 to ID3.

The recording head 206 is an ink-jet head in which ink-jet nozzles are arranged in a vertical direction, and discharges ink droplets while scanning the printing paper in the horizontal direction to perform recording on the printing paper. The recording head 206 includes a monochrome head capable of printing only black,
There is a color head capable of printing in three colors, magenta and cyan, and the user selects one of the heads and mounts it on the printer. An HID signal for identifying the type of the head is output from the recording head 206 and input to the CPU 1. The CPU 1 determines whether the mounted head is a monochrome head or a color head based on whether the HID signal is at a high level or a low level.

FIG. 8 shows a nozzle (dot) configuration of the recording head. In FIG. 8, reference numeral 206a denotes a monochrome head;
Reference numeral 06b denotes a nozzle configuration of the color head. In the monochrome head 206a, 64 nozzles are arranged in a line at intervals of 1/360 inch, and all nozzles eject black ink. In the color head 206b, 48 nozzles are arranged in a line, and yellow 16 dots, magenta 1
It is composed of 6 dots and 16 cyan dots, and a gap of 8 dots is provided between each color.

FIG. 9 is a circuit diagram for explaining the electrical configuration of the color head. The basic configuration is the same as the circuit configuration of the monochrome head shown in FIG. 2, but of the 48 heater resistors 41, 16 heater resistors connected to the common terminals CM1 and CM2 are used to discharge yellow ink. Used,
The 16 heater resistors connected to the common terminals CM4 and CM5 are used for magenta ink ejection, and
The 16 heater resistors connected to 8 are used for discharging cyan ink. Common terminals CM3 and 6 for color head
Is not used.

FIG. 10 is a block diagram showing a circuit configuration of the head driver 7. For ink detection, signals ID1 to ID3 obtained by dividing the common terminals CM2, CM5 and CM8 of the recording head 6 with resistors are used as AD conversion terminals 1 to 3 of the CPU 1.
It is connected to the.

Of the heater resistance 41 of the recording head 6, C
The heater resistors connected to M1 and CM2 are capacitively connected by yellow ink. The heater resistors connected to CM4 and CM5 are capacitively connected by magenta ink, and the heater resistors connected to CM7 and CM8 are capacitively connected by cyan ink.

FIG. 11 is a timing chart at the time of ink detection when the color head is used. In FIG. 11, by driving the common control signal COM1, the potential of the common terminal CM1 rises. Common terminal C
The voltage change of M1 is applied to the common terminal CM by yellow ink.
2, the voltage of CM2 changes depending on whether there is yellow ink in the nozzle portion. The voltage of CM2 is divided into a logic level signal ID1 by a resistor,
1 AD converter terminal. Therefore, by reading the potential of the signal ID1 at the time t1 with the AD converter, the presence or absence of yellow ink can be detected. Similarly, the presence or absence of magenta ink can be detected by reading the potential of the signal ID2 at the time t2 when the common control signal COM4 is driven,
By reading the potential of the signal ID3 at the time t3 when the common control signal COM7 is driven, the presence or absence of cyan ink can be detected.

As described above, by utilizing the change in the capacitance between the heater resistors depending on the presence or absence of ink in the nozzle portion of the recording head, the color head can also prepare the voltage-dividing resistors for each color, and thus, use only the voltage-dividing resistors for each color. The presence or absence of ink can be detected independently.

[0037]

As described above, according to the present invention,
The presence / absence of ink and defective ejection can be automatically detected with a simple configuration.

Further, according to the second and fourth aspects of the present invention, it is possible to automatically recover from a discharge failure, and the third and fourth aspects of the present invention can easily know that the ink has run out.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part according to a first embodiment.

FIG. 2 is a circuit diagram of a recording head.

FIG. 3 is a circuit diagram of a head driver.

FIG. 4 is a timing chart of a head control signal during printing.

FIG. 5 is a timing chart of ink detection.

FIG. 6 is a flowchart showing an operation for detecting the remaining amount of ink.

FIG. 7 is a block diagram illustrating a configuration of a main part of the second embodiment.

FIG. 8 is a diagram showing a nozzle configuration of a monochrome head and a color head.

FIG. 9 is a circuit diagram of a color head.

FIG. 10 is a circuit diagram of a head driver.

FIG. 11 is a timing chart of ink detection when a color head is used.

[Explanation of symbols]

 1 CPU 5 Printer control IC 6 Recording head ID Signal obtained by dividing common terminal CM2 with a resistor

Claims (7)

[Claims] A recording head having a plurality of recording elements for ejecting ink droplets; a driving unit for selectively driving each recording element of the recording head; and a plurality of signals connecting the driving unit to the recording head. And changing the voltage of the first predetermined signal line in the signal line without driving the recording head, and synchronizing with the change in the voltage, the second predetermined signal line in the signal line. An ink jet printing apparatus comprising: an ink detecting unit that detects a voltage and detects presence or absence of ink based on the voltage. 2. An ink jet printing apparatus according to claim 1, further comprising: a recovery unit for recovering a discharge failure of the recording head; and a unit for operating the recovery unit when the ink detection unit detects that there is no ink. An inkjet printing apparatus characterized by the above-mentioned. 3. An ink jet printing apparatus according to claim 1, further comprising: display means for displaying that the recording head has run out of ink; and means for causing said display means to display that the ink has run out when the ink detection means detects that there is no ink. An inkjet printing apparatus comprising: 4. A recording head having a plurality of recording elements for ejecting ink droplets, driving means for selectively driving each recording element of the recording head, and a plurality of signals connecting the driving means and the recording head. And changing the voltage of the first predetermined signal line in the signal line without driving the recording head, and synchronizing with the change in the voltage, the second predetermined signal line in the signal line. An ink detecting unit that detects a voltage and detects the presence or absence of ink based on the voltage; a recovery unit that recovers a discharge failure of the recording head; a display unit that indicates that the recording head is out of ink; and the ink detecting unit. Control means for operating the recovery means when detecting the absence of ink, and thereafter operating the ink detection means, and causing the display means to display an out-of-ink state when detecting the absence of ink. Inkjet printing apparatus characterized by the. 5. The ink-jet printing apparatus according to claim 1, further comprising a recording head capable of printing a plurality of colors, the first signal line and the second signal. An ink jet printing apparatus comprising a line for each color. 6. The ink jet printing apparatus according to claim 1, wherein the plurality of signal lines are connected to heater resistors of the plurality of printing elements. Inkjet printing apparatus. 7. A method for detecting the presence or absence of ink in a recording head having a plurality of recording elements, wherein a driving element for driving the recording element is used as an electrode, and a change in capacitance of a capacitor using the ink as a dielectric is used to detect the presence of ink. A method for detecting the presence or absence of ink, characterized by detecting the presence or absence.