JPH03218845A - Ink jet printer - Google Patents

Abstract

PURPOSE:To make it possible to dispense with the arrangement of a special detection device and detect or inform a residual amount of ink without any cost increase by detecting the residual amount of ink in accordance with the response variations of a controlled object. CONSTITUTION:If there is ink in an ink tank 30 on a carriage 6 or in a jet head on the carriage 6, the mass of the carriage is larger than when it is not filled with ink. In addition, the gravitational center moves when the speed of the carriage is accelerated. Subsequently, if the same PWM value is given, the accelerated speed is lower than when the carriage is not filled with ink, resulting in the low response rate of a controlled object. Therefore, when the actual carriage speed is higher than a target speed, the presence of ink of the low-level residual amount of ink can be detected by comparing a value stored previously in ROM, that is, an estimated minimum PWM duty with a calculated PWM value. If the detection is made, 'no ink' flag provided in RAM is set to be ON. If the flag is ON, 'no residual ink' display lamp on a control panel 160 is turned ON to prompt a replacement of an ink tank 30.

Description

DETAILED DESCRIPTION OF THE INVENTION E-INDUSTRIAL APPLICATION FIELD The present invention relates to an inkjet printer, and particularly to an inkjet printer that performs printing by scanning a recording medium with an inkjet recording head in a predetermined direction, and uses an ink tank as an ink supply means. This also relates to an inkjet printer that is moved during scanning, that is, for example, an inkjet printer that has an ink tank attached to a carriage on which an inkjet recording head is mounted, or an inkjet printer that uses a cartridge that integrates an inkjet recording head and an ink tank. be.

[Prior Art] Conventionally, inkjet printers have been equipped with electrodes in the ink tank to detect changes in resistance between the electrodes in order to detect the remaining amount of ink in the ink tank. It was common practice to detect the presence or absence of ink.

In other words, the remaining amount of ink has been detected by providing some kind of device for ink detection.

[Problems to be Solved by the Invention] However, since some kind of detection device was added to detect the remaining amount of ink, the cost of the apparatus increased by the amount of the detection device.

It is an object of the present invention to make it possible to detect the remaining amount of ink, particularly in the above-mentioned inkjet printer, without adding a special detection element, that is, without increasing costs.

[Means for Solving the Problems 1] To this end, the present invention performs printing while scanning a recording medium with an inkjet recording head in a predetermined direction, and at the same time, the present invention provides an inkjet recording head that is supplied to the inkjet recording head during the scanning. In an inkjet printer that moves an ink supply means storing ink, means for detecting the responsiveness of the ink supply means or its driving means when the ink supply means or its driving means is driven; The apparatus is characterized by comprising means for detecting the remaining amount of ink.

E-Function] According to the present invention, the remaining amount of ink is detected based on a change in the responsiveness of the controlled object (a motor or a carriage equipped with an ink tank), so there is no need to provide a special member for detection. It becomes possible to detect or notify the remaining amount of ink without increasing costs.

[Example] Hereinafter, the present invention will be explained in detail with reference to the drawings.

(Embodiment 1) FIG. 1 shows an embodiment of an inkjet printer to which the present invention can be applied.

In FIG. 1, a recording medium 1 such as paper or a plastic sheet is supported by conveyance rollers 2 and 3 consisting of a pair of rollers arranged above and below a recording area, and conveyance rollers 2 and 3 are driven by a sheet feed motor 4. is transported in the direction of arrow A. A guide shaft 5 is provided in front of and parallel to the conveyance rollers 2 and 3. A carriage 6 is reciprocated along this guide shaft 5 in the direction of arrow B via a wire 8 by the output of a carriage motor 7 in the form of a DC motor, for example. Although not shown in FIG. 1, a rotary encoder used for motor control is coupled to the output shaft of the carriage motor 7.

A recording head unit 9, which is a BJ type inkjet head, is mounted on the carriage 6. The front surface of the recording head 9, that is, at a predetermined distance from the recording medium 1 (for example, 0
．． A recording section in which a plurality of ink ejection ports are arranged in a vertical row is provided on opposing surfaces with a distance of 8 mm.

That is, a plurality of ink ejection ports are formed at a predetermined pitch in the vertical direction on the surface facing the recording medium 1, and an ejection energy generating element (heating resistor, etc.) inside each ink ejection port is driven based on recording information. Bubbles 1) are generated in the ink by electrical heating (heating), and the pressure generated at this time forms flying ink droplets, and recording is performed while ink dots are attached to the recording medium 1 in a predetermined pattern.

The recording head 9 is equipped with a circuit board for a drive circuit (driver) 29 for driving as described above. Further, ink is supplied to the recording head 9 from an ink tank 30 in the form of a cartridge, for example, which is mounted on the carriage 6 .

The control circuit (CPU) of the recording device and the RO attached to it
A control unit including M, RAM, etc. is formed on the control board 15, and this control unit receives command signals and data signals (recorded information) from a host device l4 such as a computer, and performs various types of processing based on the received command signals and data signals (recorded information). A drive voltage (heat voltage) for the electrothermal transducer is applied to the recording head 9 through the heat driver 13 together with a drive source such as a motor.

An online/offline switching key 1 is provided on the operation panel 160 attached to the exterior case (not shown) of the recording device.
6A, line feed key 16B, form feed key 16C, recording mode switching key 160, and other key setting sections, as well as several alarm lamps 16E, such as a lamp to notify when there is no remaining ink, a power lamp 16F, etc. A display section including a warning lamp is provided.

FIG. 2 is a block diagram showing an example of the configuration of the control system of the inkjet recording apparatus shown in FIG.

In FIG. 2, an MPU 5 in the form of a microcomputer
1 is connected to a host device 14 such as a computer, and performs recording operations based on command signals (commands) and recording information signals sent from the host device 14, as well as programs and data stored in ROM, RAM, etc. control.

The MPU 51 drives the carriage motor 7 via a motor driver 53, etc., controls the conveyance system for the recording medium 1 including the sheet feed motor 4, etc., and also controls the recording medium 1 based on recording information stored in a data memory such as a RAM. The recording head 9 is controlled via a head driver 9A.

Each operation key 16A to 16 on the operation panel 160 described above
0 (FIG. 1) via input port 32 to C
The control signal is transmitted to the PU 21, and is also supplied to warning lamps such as the alarm lamp 16E and the power lamp 16F via the output boat 36.

In Figure 2, DC is the power source that drives the carriage.
To further explain the control system of the servo motor (carriage motor 7), 52 is a PWM timer capable of generating pulses with a duty and period according to instructions from the MPU 51;
is the pulse input from the PWM timer 52 and the MPU 51
A driver 55 is attached to the shaft of the DC motor 7 to drive the motor 7 in forward and reverse directions in response to a direction instruction input from the DC motor 7, and includes a disk with slits cut out on its circumference and an optical sensor for reading the slits. Encoder unit, 56
The motor 7 is activated by the pulse from the encoder unit 55.
57 is an encoder unit 55 consisting of an up/down counter that measures the position of
A speed measurement clock generator 58 generates pulses with a constant frequency that is sufficiently higher than the pulses from the motor. A speed measurement counter 7 measures the speed, and 59 is a servo timer that generates interrupts at a constant period and causes the MPU 51 to execute servo processing.

An outline of the speed control of the motor 7 in the above configuration will be described. In this type of printer, recording and carriage movement are performed at a constant speed. In order to change from a stopped state to a constant speed state, a gentle speed curve is generally used instead of a sudden start-up in order to prevent uneven printing due to vibration of the carriage 6.

As a method for performing this speed control, an example in which a servo motor as in this embodiment is used as a drive source will be described according to the processing procedure illustrated in FIGS. 3(A) and 3(B).

The MPU 51 controls the speed of the motor 7 by feeding back the signal obtained from the encoder 55 to the PWM timer 52 in order to match the actual motor speed to the speed curve previously stored in the ROM.

First, in the procedure shown in FIG. 3(A), the MPU 51 instructs the rotation direction to the driver No. 3 at startup (step
l) Instruct the PWM timer 52 to generate a certain predetermined duty pulse (step S3).
. At the same time, an interrupt cycle is determined for the servo timer 59 to start a process (FIG. 3(B)) for correcting the PWM value for controlling the speed of the motor 7 (step S5). Thereafter, a process for permitting the interrupt is performed (step S7
), end this procedure.

Thereafter, the process moves to a known recording process, and during this process, the procedure shown in FIG. 3(B) is activated at the above-mentioned interrupt period to control the speed of the motor 7 or detect the remaining amount of ink. Further, the remaining amount of ink may be detected not only during the recording process but also during the process of moving the carriage 6.

The PWM timer 52 inputs pulses with a designated duty to the driver 53, and provides the motor 7 with power proportional to the duty. When the motor 7 rotates, the encoder unit 55 outputs pulses at a frequency corresponding to the speed of the motor 7 to the position counter 56 and speed counter 58.

In the procedure shown in FIG. 3(B), the speed of the motor 7 can be measured by measuring this pulse interval using the clock from the speed measurement clock generator 57 (step S11). The MPU 51 compares the motor speed obtained from the speed table stored in advance in the ROM with the actually measured speed at each cycle of the servo timer when an interrupt occurs by the servo timer 59 (step S13), and uses the PWM timer 52 as feedback on the difference.
A command is given to increase or decrease the duty of the output pulse (steps S15 and S17). This operation is executed by timer 5.
By performing this for each interrupt by 9, it becomes possible to control the motor speed using an arbitrary curve. That is, the carriage 6 is stably accelerated and decelerated before and after the recording area, and the carriage 6 is moved at a predetermined speed in the recording area. At this time, the electric power applied to the motor 7, that is, the PWM duty, is always within a certain range, except when a special external load is applied.

Ink tank 30 on carriage 6 or carriage 6
When there is ink in the upper head 9, the mass of the carriage is larger than when the ink is empty, and because the ink is a liquid, the center of gravity moves during acceleration, so the PWM value is the same. When the ink is given, the acceleration or response will be lower than when the ink is empty. Therefore, if the actual speed exceeds the target speed, the process proceeds to step S29 via step Sl7, and the minimum PWM duty that is expected when there is normal ink, which is the value stored in advance in the ROM, is set. and PWM
By comparing the calculated value of , it is possible to know whether there is ink or at least whether the amount of ink remaining is low.

If the detection is made, for example, an out-of-ink flag provided in the RAM is turned on (step S21).
. The MPU 51 refers to the flag at an appropriate timing, and if the flag is on, it can prompt the operator to replace the ink tank 30 by lighting an indicator lamp indicating that there is no remaining ink on the operation panel 160.

Note that before ending the interrupt processing as described above, be sure to reset the PWM timer (step S2).
3) Regardless of the amount of remaining ink, that is, regardless of the mass of the carriage 6 carrying the ink tank 30,
Since control is always performed to keep the motor speed constant in the recording area, the recording operation will not be adversely affected.

In this example, the speed is detected by a rotary encoder connected to the motor shaft of the carriage motor 7, but the configuration of such a detection means may be any type. It is also possible to detect this using a linear encoder or the like, and use the detected value for feedback control.

(Embodiment 2) FIG. 4 shows an example of the configuration of a control system according to another embodiment of the present invention, and corresponding parts are given the same reference numerals for parts that can be configured in the same manner as in the above example.

In the above example, the presence or absence of ink was detected by determining the responsiveness of the carriage or motor using a servo system, but in this example, a control system will be described when a stepping motor is used as the carriage motor 7 in FIG. 1.

In FIG. 4, 111 is a driver that drives the motor based on the phase selection signal from MPU 1, and 112 is a driver that transmits power to the carriage 6 on which the recording head 9 and ink tank 30 are mounted by means of a belt, etc., and drives the carriage 6 horizontally. A stepping motor 113 is a motor 112 that moves the
a home position sensor 114 that initializes the position of the
1 is a timer that can be accessed by the MPU 51, and 115 is a nonvolatile memory.

In the above configuration, the sensor 113 is used to initialize the position of the carriage 6, and this can be done when the power is turned on, as is done in conventional printers. The MPU 5 1 detects the position of the carriage 6 by monitoring whether this sensor 113 is turned on or off. Since the motor 112 is a stepping motor, MP
U51 can be easily started and stopped using phase information for driver 111. Further, the speed of phase switching has a correlation with the load when the power applied to the motor is constant. In other words, the lighter the load, the faster the phase changes. In this example, this fact is utilized.

The method of detecting the remaining amount of ink in this example will be explained according to the processing procedure illustrated in FIG.

The MPU 51 detects whether the current position of the carriage 6 is at the home position (step S31), and if not, moves the motor 112 in the direction toward the home position, for example, to the left, so as to enter the home position. Stop at that position (step S33,
S35, S37). If it is at the home position, the motor 112 is moved away from the sensor, for example, to the right, to a position where the sensor can no longer be detected (steps S39, S41, S43), and then turned one step to the left. The motor is stopped at the position where the output of the sensor 113 is switched when the phase is switched (steps S45, S47).

Next, while starting the timer 114 (step S49)
, rotate the motor one step to the right (step S5
1, S53), the timer 114 measures the time from startup until the sensor output switches (step S55,
S57). By comparing this time with a value previously measured when there is sufficient ink in the ink tank and stored in the nonvolatile memory 115 (step S61), the weight of the carriage, that is, the amount of ink in the ink tank on the carriage is determined. It becomes possible to detect whether there is a remaining amount of ink (steps S63, S65). By performing this operation at regular intervals, the remaining amount of ink is constantly detected.

Note that the setting of the reference value (steps S59, S67) is as follows:
A switch or command for this purpose may be set, and the measurement operation may be executed when the switch is pressed or a command is received. Alternatively, when the ink tank is replaced by a sensor capable of detecting the presence or absence of the ink tank 30, that is, when a "one exists, one is missing, one exists" sequence occurs, a new tank sufficiently filled with ink is installed. Another possible method is to perform this measurement operation based on the assumption that the The reference value can be set by simply writing the value read from the timer into a non-volatile memory such as EEFROM.

In the configuration shown in the first drawing, the recording head and the ink tank are provided separately, and the ink tank is in the form of a cartridge and is removable from the carriage 6, but the present invention is not limited to this form. , various configurations can be adopted. For example, the recording head and the ink tank may be integrated and made replaceable. Alternatively, the ink tank may be mounted on a separate carriage from the carriage on which the recording head is mounted, and the ink tank may be made to follow the carriage. Furthermore, the ink tank does not necessarily have to serve as an ink supply source; for example, it may be in the form of a sub-tank placed between a main ink tank fixed within the apparatus and a recording head.

(Others) The present invention brings about excellent effects particularly in a bubble jet type recording head and recording apparatus among inkjet recording types.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in a one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one drop. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. This pulse-shaped drive signal is described in U.S. Pat. No. 4,463,359 and U.S. Pat.
Those described in the specification are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid channels, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. U.S. Pat. No. 4,558,333 discloses a configuration in which a curved area is disposed in a bending area. A configuration using the specification of US Pat. No. 4,459,600 is also included in the present invention. In addition, Japanese Patent Application Laid-Open No. 1989-5 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Application Laid-Open No. 59/1989 which discloses a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
- The effects of the present invention are also effective even with a configuration based on Publication No. 138461. That is, regardless of the form of the recording head, the remaining amount of ink can be detected reliably and efficiently.

In addition, even the serial type shown in the above example is a replaceable chip type recorder that can be attached to the device body to enable electrical connection to the device body and ink supply from the device body. The present invention is also effective when using a cartridge type recording head that is provided integrally with the head or the recording head itself.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, the inkjet recording apparatus of the present invention may take the form of an image output terminal for information processing equipment such as a computer, a copying apparatus combined with a reader, etc., or a facsimile apparatus having a transmitting/receiving function. It may be something.

[Effects of the Invention] As explained above, according to the present invention, the remaining amount of ink is detected based on the change in the responsiveness of the controlled object (the motor or the carriage equipped with the ink tank).
There is no need to provide a special member for detection, and the remaining amount of ink can be detected or notified without increasing costs.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view of an inkjet printer according to an embodiment of the present invention, Fig. 2 is a block diagram showing an example of the configuration of its control system, and Figs. 3 (A) and (B) are its control procedures. FIG. 4 is a block diagram showing a configuration example of a control system of an inkjet printer according to another embodiment of the present invention. FIG. 5 is a flow chart showing an example of the control procedure. 6... Carriage, 7... Carriage motor (DC motor) 9... Recording head, 30... Ink tank, 5l... MPU, 52... PWM timer, 55... Encoder unit, 58... Counter, 59... Servo timer, 112... Carriage motor (stepping motor)
, 113... Home position sensor, 114... Timer, 160... Operation panel. Figure 3 (B)

Claims (1)

[Scope of Claims] 1) An ink supply means that performs recording while scanning a recording medium with an inkjet recording head in a predetermined direction, and stores ink to be supplied to the inkjet recording head during the scanning. In an inkjet printer to be moved, means for detecting the responsiveness of the ink supply means or its driving means during driving; and means for detecting the remaining amount of ink stored in the ink storage means according to a change in the responsiveness. An inkjet printer characterized by: 2) The inkjet printer according to claim 1, wherein the inkjet recording head has a heating element that generates thermal energy as energy used for ejecting ink.