JP2730918B2 - Method for detecting remaining amount of ink in ink jet recording apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting the remaining amount of ink in an ink jet recording apparatus.

[Prior Art] FIG. 1 shows a serial type ink jet recording apparatus, in which 1 is a paper feed motor, 2 is a motor gear connected to a rotating shaft of a motor 1, and 3 is a paper feed gear meshed with a motor gear 2. is there. Reference numeral 4 denotes a platen, on which a recording paper 5 is wound around a cylindrical side surface to form a recording surface, and a longitudinal axis of the platen 4 is a paper feed gear 3
Paper feeding is performed by combining with.

Reference numeral 6 denotes a recording head, which forms dots by discharging ink from ink discharge ports of the head 6, thereby forming characters and characters.
Record images and the like. Reference numeral 7 denotes a sub-ink tank disposed near the recording head 6, and the recording head 6 and the sub-ink tank 7 are connected by a member (not shown) such as a tube for supplying ink. The sub-ink tank 7 has a buffer function for preventing a sudden pressure from being applied to the head 6.

Reference numeral 8 denotes a carriage on which the recording head 6 and the sub-ink tank 7 are mounted. Reference numeral 13 denotes a carriage shaft that supports the carriage 8 and regulates the operation direction. 12 is a carriage motor, 10 is a motor pulley coupled to the rotation shaft of the carriage motor 12, 11 is an idler pulley, and a motor pulley.
The idler pulley 10 and the idler pulley 11 are arranged at an interval corresponding to the length of the platen 4 in the longitudinal direction. 9 is a timing belt, which is stretched by pulleys 10 and 11,
When the timing belt 9 and the carriage 8 are engaged, the recording head 6 performs recording while moving in the longitudinal direction of the platen 4 along the recording paper 5.

Reference numeral 14 denotes an ink cartridge serving as an ink supply source, in which an ink bag 30 is housed. The ink cartridge 14 and the sub-ink tank 7 are connected by a flexible tube 16 via an ink remaining amount detection Kochi 15 described later with reference to FIGS. I do.

FIG. 2 is a perspective view showing details of the ink remaining amount detecting device, and FIGS. 3 and 4 show cross sections AA in FIG.

In these figures, 25 and 29 are an upper case and a lower case, respectively, which constitute the main body of the detection device 15. The lower case 29 is provided with an ink liquid chamber 19, and further includes a flow path for flowing ink into the ink liquid chamber 19 and a flow path for flowing ink from the ink liquid chamber 19. An ink inflow path 18 and an ink outflow path 20 are provided, respectively. 21 is an elastic diaphragm, 22 is a contact, and the upper case 25
A switch is constituted by the two contacts 26 fixed to the switch and intermittently switches the electric signal in the remaining amount detection. A top view of this configuration is shown in FIG. 23 is a contact pressure contact material.

The center of the diaphragm 21 is sandwiched by the contact 22 and the contact pressure contact member 23, and the peripheral edge is sandwiched by the upper case 25 and the lower case 29, respectively. Reference numeral 24 denotes a contact pressure contact material holder, which is disposed at the center of the upper case 25 so as to be slidable in the vertical direction.

Further, the contact pressure contact member 23 is press-fitted into the holder 24 and attached thereto, whereby the contact pressure contact member 23, the diaphragm 21,
The contact 22 and the holder 24 operate integrally. Further, the holder 24 has a threaded portion, a stopper 28 is screwed into the threaded portion, and a compression coil spring 27 is inserted between the stopper 28 and a seat arranged at the center of the upper case 25, The holder 24 is urged upward. Terminals 15a and 15b are connected to an ink remaining amount detection circuit (not shown).

With the above-described configuration, when the pressure in the ink liquid chamber 19 changes in accordance with the remaining amount of ink, the stopper 28, the holder 24, and the contact pressure contact are formed in accordance with the relationship between the changed pressure and the elastic force of the coil spring 27 and the diaphragm 21. The member 23, the diaphragm 21, and the contact 22 integrated with these members move up and down. The switch composed of the contacts 22 and 26 opens and closes by the up and down operation of the contact 22. That is, when the contact 22 is lowered and becomes out of contact with the contact 26, the switch is opened, and the remaining ink amount detection circuit issues a warning that the remaining ink amount is small.

The state of the pressure inside the ink supply system can be considered as follows.

That is, the ink bag 30, the tube 16, and the ink liquid chamber 1
Considering the change rate of the total ink amount and the total volume in the ink supply system composed of 9, the ink amount reduction rate is almost constant with respect to the ink discharge amount, while the volume change rate of the entire ink supply system is This is caused exclusively by the change of the ink bag 30, and the deformation decreases as the remaining amount of ink decreases, so that the volume change rate decreases. From the above, the pressure inside the supply system decreases as the remaining amount of ink decreases.

3 and 4 are views showing the position of the contact 22. The position shown in FIG. 3 is a state where the contact 22 and the contact 26 are in contact with each other and the switch is closed. In many cases, the pressure in the ink liquid chamber 19 is not reduced. On the other hand, FIG. 4 shows a state in which the contacts 22 and 26 are separated from each other and the switch is opened, in which the remaining amount of ink is small and the pressure in the ink liquid chamber 19 is reduced.

The conditions for opening or closing these switches are as follows: N is the reaction force of the elastic restoring force of the diaphragm 21, F is the force of the coil spring 27, Pa is the force applied to the diaphragm 21 by the atmospheric pressure, Pa is the supply system (ink liquid). If the force due to pressure is Pi, the switch is closed when N + F ≧ Pa−Pi (1), and the switch is opened when Pi decreases and N + F <Pa−Pi (2) When

As is apparent from equations (1) and (2), the stopper
If the force F of the coil spring 27 is adjusted by rotating the position of the coil spring 27 and adjusting the force F, the switch is opened when the desired amount of ink has been reached, that is, when the pressure in the ink liquid chamber 19 has a predetermined value. It can be configured as follows.

In the configuration of the remaining amount detection device 15 described above, during the recording operation, by constantly supplying current to the contact 26, the contact state between the contact 26 and the contact 22 is monitored. The warning that the remaining amount of ink is low was issued.

[Problems to be Solved by the Invention] However, in a serial type ink jet recording apparatus, the recording head performs a reciprocating operation, and the ink supply tube follows the operation along with this operation. Ink flows into or out of the sub-ink tank due to inertial force. As a result, a pressure fluctuation occurs inside the ink supply system. However, since the ink bag cannot be deformed in response to the instantaneous pressure fluctuation, the pressure fluctuation cannot be fully absorbed and the force Pi due to the ink supply system internal pressure fluctuates.

Therefore, the states shown by the above equations (1) and (2) may appear alternately with the recording operation, regardless of the remaining ink amount.

In such a state, when N + F = Pa-Pi is established, the contact pressure between the contact 22 and the contact 26 becomes almost zero, and the contact state between these contacts becomes unstable. Therefore, the contact resistance between the contacts, in other words, the current flowing between the contacts becomes unstable. At this time, if the gap between the contact 22 and the contact 26 is very small, a discharge phenomenon may occur, and an oxide film is formed on the surfaces of the contact 22 and the contact 26 by this discharge.

If the above-mentioned state frequently occurs during the recording operation by keeping the contact always in the conducting state, an oxide film on the contact surface grows and the contact resistance between the contacts increases.

As a result, even though the contact points 22 and 26 are in sufficient contact, the state is de-energized, and it is detected that the remaining amount of ink is small before the remaining amount of ink reaches a predetermined value. There has been a problem that the reliability of the remaining amount detection device is low.

In addition, if the ink cartridge or the like is replaced in accordance with the detection of the remaining amount having a lack of reliability, the use of the ink becomes uneconomical.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to supply a current to a contact only when it is necessary to detect the remaining amount of ink, and to form an oxide film on the contact surface by discharging. An object of the present invention is to provide an ink remaining amount detecting method capable of performing highly reliable remaining amount detection by minimizing formation.

[Means for Solving the Problems] For this purpose, according to the present invention, there is provided a recording head for discharging ink, an ink tank for supplying ink to the recording head, and an ink supply path from the ink tank to the recording head. Detecting means for detecting an increase in negative pressure in the ink supply path due to a decrease in the remaining amount in the ink tank by a contact switch interposed and opened and closed according to pressure fluctuations in the ink supply path. In the method for detecting the remaining amount of ink, the contact switch is energized only when detecting whether or not the remaining amount in the ink tank has decreased.

[Operation] According to the above configuration, the detecting means for detecting an increase in the negative pressure in the ink supply path due to a decrease in the remaining amount in the ink tank by the contact switch that opens and closes in response to the pressure fluctuation in the ink supply path. In the ink remaining amount detection using, the contact switch is energized only when it is detected whether or not the ink remaining amount has decreased, so the pressure in the ink supply path fluctuates due to factors other than the ink remaining amount decreasing. However, even if an unstable contact occurs in the contact switch, the contact switch is not energized in this case, so that a discharge phenomenon due to the contact can be prevented, and an oxide film is formed on the contact surface. Can be minimized.

EXAMPLES Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

FIG. 6 is an explanatory view for explaining an embodiment of the present invention. In the figure, reference numeral 17 denotes a head unit including the recording head 6, the sub ink tank 7, and the carriage 8. In the recording device, the head unit 17 and the tube
Only 16 moves with the recording, and the solid line in the figure shows the case where the head unit 17 reaches the left end of the moving range for recording, and the two-dot chain line in the figure shows the case where the head unit 17 reaches the right end.

The moment the head unit 17 stops at the left end, the tube 16
Ink portion corresponding to the length indicated by L ₁ of the inner is trying flow into the sub ink tank, causing a movement of the ink in the entire ink supply system. The ink bag 30 cannot be deformed following the movement of the ink, so that the pressure inside the ink supply system decreases. Meanwhile, at the moment when the head unit 17 is stopped at the right end, and likely flow out the ink of the portion corresponding to the length indicated by L ₂ in the tube 16 from the sub ink tank 7, an internal ink supply system for the same reason as that described above Pressure increases.

Here, since L ₁ > L ₂ , the influence on the above-mentioned movement of the ink is smaller, obviously in the case of L ₂ , that is, at the moment when the head unit 17 stops at the right end. Therefore, if the ink remaining amount is detected at this point,
Since the detection can be performed in the state closest to the set pressure in the ink chamber corresponding to the predetermined remaining amount of ink, the head unit 17
When stops at the right end, the contact 26 of the remaining amount detecting device 15 is energized, and the contact state between the contact 26 and the contact 22 is detected.

While the head unit 17 moves with the recording, the state of the ink in the tube 16 changes every moment, and the state of the switch of the remaining amount detection device 15 becomes unstable, which is not suitable for accurate remaining amount detection. It is.

In the above-described embodiment, the case where the curved portion 16a of the tube 16 is formed on the right side of the head unit 17 is shown. However, as shown in FIG.
For the same reason, when the head unit 17 stops at the left end, the remaining ink amount is detected.

In addition, the surface formed by the curved portion 16a of the tube 16 becomes various due to dust and the like, and it goes without saying that the present invention is effective regardless of the curved surface.

FIG. 8 is a block diagram showing a control configuration of the ink jet recording apparatus shown in FIG. In the figure, reference numeral 31 denotes a CPU for controlling the operation of the entire apparatus, which is composed of a microprocessor element and the like. Data to be recorded is transmitted from a host device 30 such as a computer system to a CPU 3 via a recording data receiving unit 32 constituted by a known interface circuit such as a parallel / serial interface.
Transferred to 1. The CPU 31 controls the recording head 6 via the head driving unit 33 and the head driving unit 34 based on the transferred data.

At this time, the driving timing of the recording head 6 is determined by the timer 35.
Is controlled at a predetermined timing. Also timer
Reference numeral 35 is also used to determine a detection interval of an ink remaining amount detection switch described later. When the print data transmitted from the host device 30 is a character or a symbol, the data is transferred in the form of a character code, and is converted into dot image data so that the printer can print with a dot matrix type print head. For this purpose, the CUP 31 is provided with a character generator ROM (CGROM) 36. Also, CPU3
The control program in 1 is stored in the control ROM 37. Furthermore, since it is used as a work area of the CPU 31 or a buffer area for transferred recording data, the RA
M38 is provided.

The contact information from the remaining amount detection terminals 15a and 15b for transmitting the above-mentioned contact information of the ink remaining amount device 15 is input to an input port 40 composed of a flip-flop element or the like via an ink remaining amount detection circuit 39 described later. Then, the CPU 31 reads this to detect the remaining amount of ink.
The output port 41 controls the ink remaining amount detection circuit 39 and controls the mechanical mechanism of the printing apparatus such as the carriage motor 11 according to the control signal output from this port.

FIG. 9 shows an embodiment of the ink remaining amount detecting circuit shown in FIG. 8, and the operation will be described below with reference to the drawings.

One terminal 15a of the contact 26 in the ink remaining amount detecting device 15 is connected to the output of the open collector type inverter 50, and the input of the inverter 50 is connected to the output port 41 shown in FIG.
It is connected to the. The other terminal 15b is input to the input port 40, and its signal line 54 is pulled up to a positive power supply via a resistor 51.

When detecting the ink remaining amount, the CPU 13 outputs the output port 41
H level signal is written to the signal line 52 of the output port 41.
Is fixed at the H level. The signal line 52 is connected to the inverter 50
, The output signal line 53 of the inverter 50 becomes L level, and the terminal 15a in the remaining ink amount detector 15 is fixed at L level.

Here, when the remaining ink amount is equal to or more than the specified value, the contact points 22 and 26 are in contact with each other, and the terminals 15a and 15b are closed. The signal line 54 to which the switch current flows and is input to the input port 40 is fixed at the L level.

On the other hand, if the remaining ink amount is less than the specified value, the terminal 15a
And the terminal 15b is open, so that no current flows through the switch and the signal line input to the input port 40
54 is fixed at the H level.

The CPU 31 sends a signal line 54 to these input ports 40
By reading the logic level, the remaining amount of ink can be detected.

When the remaining ink level is not detected, CPU 31
By writing the L level to 1, the output line 53 of the open collector type inverter 50 is set to the high impedance state, and the current flows between the contacts regardless of the state between the terminals 15a and 15b, that is, regardless of the state of the remaining ink. Not to flow.

As described above, by writing the H level to the output port 41 only when the state of remaining ink is detected, it is possible to provide a circuit for detecting the amount of remaining ink that can be energized between the contacts.

In the above description, the TTL is taken as an example of the inverter 50, but it is clear that the inverter 50 can be realized by using an open drain type inverter.

Next, the procedure for detecting the remaining amount of ink in the recording apparatus as shown in FIG. 1 will be described with reference to the flowcharts in FIGS.

FIG. 10 is a flowchart showing a processing procedure when a curved portion of the tube is formed on the right side of the head unit 6 as shown in FIG. When the apparatus is turned on in FIG. 10, the apparatus is initialized in step S101, and the head unit 17 moves to the home position on the left end in FIG. 1 serving as a reference for the recording operation and stops. After the stop, in step S102, the L level is written to the output port 41, the terminal 15a side in the ink remaining amount detecting device is set to high impedance, and even if the contact 26 and the contact 22 are closed, between the terminal 15a and the terminal 15b. Make sure no current flows. If there is a recording command here, in step S103, the head unit 17 performs recording while moving from left to right in FIG. After the recording of the required digits of the line is completed, the H level is written to the output port 41 to read the state of the contact switch in step S105, and the terminal 15a is written.
Side to L level. Next, in step S106, the CPU 31 determines the contact state between the contacts by reading the logic level of the input port 40, and detects the remaining amount of ink. Here, when the input port 40 is at the L level, the ink remaining amount device
Since the contact switch in 15 is closed, it is determined that the remaining amount of ink is equal to or more than the specified value, and the process proceeds to step S107, in which the L level is written to the output port 41 to prevent the current from flowing through the switch. Next, in step S108, recording is performed from right to left in FIG. 1. After recording of the required digits is completed, the head unit 17 is stopped in step S109. Then, step S103 again
And the normal recording operation is repeated.

If the input port 40 is at the H level in step S106, the process proceeds to step S110, in which the specified value is set in the timer 35 shown in FIG. 8 and the timer is started. Step S1
If the timer times out after the specified time elapses in step 11, the remaining ink amount is detected again in step S112.

At this time, if the input port 40 is read as L level, it is determined in the determination in step S106 that the state of the contact switch is unstable due to disturbance such as movement of ink or the influence of external noise such as static electricity. Judge,
Assuming that the remaining amount of the ink is equal to or more than the specified value, the L level is written to the output port 41 in step S113 to prevent the current from flowing through the contact switch.

If the input port 40 is read as H level in step S112, the contact switch is open, so it is determined that the remaining amount of ink is equal to or less than the specified value, and the flow advances to step S114 to write L level to the output port 41. After that, in step S115, an error processing routine in which the remaining amount of ink is equal to or smaller than a specified value is performed.

When the head unit stops after the series of processes described above, that is, recording from left to right, the contact state is detected twice at intervals of a predetermined time (several msec to 10 msec) during this stop, and In both cases, when the contact is opened, the processing for determining that the remaining amount of ink is equal to or less than the specified value makes it possible to accurately detect the remaining amount of ink excluding the influence of disturbance.

In the error processing routine of step S115, for example, control is performed to turn on a display element (not shown) such as an LED that indicates lack of ink provided on the exterior of the printer and stop the recording operation.

FIG. 11 is a flowchart for explaining a control procedure in the case where the curved portion of the tube 16 is formed on the left side of the head unit 6 as opposed to FIG. 6 as shown in FIG.

In FIG. 11, after the power supply of the apparatus is turned on, initialization of the apparatus is performed in step S201 as in FIG. 10, and the head unit moves to the home position at the left end of the apparatus and stops. After the stop, at step S202, the L level is written to the output port 41,
Prevents current from flowing through a switch in the ink remaining amount detecting device. When a recording command is input, recording is performed from left to right in step S203, and the recording is stopped after the recording is completed in step S204. Next, recording is performed from right to left in step S205, and the necessary digits are recorded.
17 stops. After stopping the head unit 17, step S2
By writing the H level to the output port 41 at 07, the remaining ink amount is detected at step S208.

Here, when the input port 40 is at the L level, it is determined that the remaining ink amount is equal to or more than the specified value, and the process returns to the step S202. After the L level is written to the output port 41, a normal recording operation is performed.

In step S208, when the input port 40 is at the H level,
In step S209, the timer is started, and in step S210
When the timeout is detected in step S211, the process proceeds to step S211, and the remaining amount is detected by detecting the level of the input port 40 again. Here, when the L level is detected, it is determined that the ink remaining amount is equal to or more than the specified value, and the process returns to step S202, outputs the L level to the output port 41, and performs normal printing.

In step S211, when the input port 40 is detected to be at the H level, it is determined that the remaining amount of ink is equal to or less than the specified value, as described with reference to FIG. 10, and the process proceeds to the error processing routine of step S213.

By executing the processing procedure described in the flowcharts of FIGS. 10 and 11 above, the direction in which the curved portion of the ink supply tube for supplying ink to the recording head is formed with respect to the recording head of the serial inkjet recording apparatus. The remaining amount of ink can be detected when the recording head stops in the same direction as the above, and the contact switch can be energized only when the remaining amount of ink is detected.

[Effects of the Invention] As is clear from the above description, an increase in the negative pressure in the ink supply path due to a decrease in the remaining amount in the ink tank is detected by the contact switch that opens and closes according to the pressure fluctuation in the ink supply path. In detecting the remaining amount of ink using the detecting means,
Only when it is detected whether or not the remaining ink amount has decreased, the contact switch is energized, so that the pressure in the ink supply path fluctuates due to factors other than the remaining ink amount,
This can cause unstable contact on the contact switch,
In this case, since the contact switch is not energized, the occurrence of a discharge phenomenon due to the contact can be prevented, and the formation of an oxide film on the contact surface can be suppressed as much as possible.

As a result, the contact state of the contact switch can be accurately detected as an electrical interruption, and a highly reliable remaining ink amount detection can be performed.

[Brief description of the drawings]

1 is an external perspective view of a serial type ink jet recording apparatus to which the present invention can be applied, FIG. 2 is an external perspective view of the remaining amount detecting device shown in FIG. 1, and FIG. 3 is the residual amount in FIG. FIG. 4 is an AA cross-sectional view showing a state in which the contact of the detection device is closed, FIG. 4 is an AA cross-sectional view showing a state in which the contact is also open, and FIG. 6 and 7 are top views for explaining an embodiment of the present invention, FIG. 8 is a block diagram showing a control configuration of the apparatus shown in FIG. 1, and FIG. 9 is a block diagram showing an embodiment of the present invention. FIG. 10 is a circuit block diagram showing an ink remaining amount detecting circuit, FIG. 10 is a flowchart showing a control procedure of the embodiment shown in FIG. 6, and FIG. 11 is a flowchart showing a processing procedure of the embodiment shown in FIG. 15a, 15b Terminal, 16 Tube, 16a Curved portion, 17 Head unit, 18 Ink inlet channel, 19 Ink chamber, 20 Ink outlet channel, 21 Diaphragm , 22… Contact, 23… Contact pressure material, 24… Contact pressure material holder, 25… Upper case, 26… Contact, 27… Compression coil spring, 28… Stopper, 29… Lower case, 31 ... CPU, 35 ... Timer, 39 ... Ink remaining amount detection circuit, 40 ... Input port, 41 ... Output port, 50 ... Inverter.

Claims (2)

(57) [Claims] A recording head for discharging ink; an ink tank for supplying ink to the recording head; and a pressure intervening in a supply path of ink from the ink tank to the recording head. Detecting means for detecting an increase in negative pressure in the ink supply path due to a decrease in the amount of ink remaining in the ink tank by means of a contact switch that opens and closes according to the amount of ink remaining in the ink tank. A method for detecting the remaining amount of ink, wherein the contact switch is energized only when it is detected whether or not the remaining amount of the ink has decreased. 2. The ink jet printer according to claim 1, wherein said detecting means includes an ink liquid chamber interposed in an ink supply path, and an elastic member provided in said ink liquid chamber and moved in accordance with a pressure change in the ink supply path. 2. The method according to claim 1, wherein the contact switch includes a contact fixed to the ink chamber and a contact that moves integrally with the elastic member.