JPH0712671B2 - Inkjet printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer, and more particularly to an inkjet printer that performs recording by ejecting ink droplets from a plurality of nozzles onto a recording paper according to a recording signal. .

2. Description of the Related Art Inkjet printers are non-impact recording methods that produce almost no noise during recording, among printers that employ various recording methods, are capable of high-speed recording, and perform special fixing processing on plain paper. You can record without recording.

Utilizing such characteristics, it is widely adopted as a printing device such as various printers, copying machines, and word processors.

This type of inkjet printer is one that ejects minute droplets from nozzles using various principles to perform recording on recording paper. Generally, an inkjet nozzle head for forming droplets of ink is used. , And a supply system for supplying ink to this head.

Although such an ink jet printer is an excellent recording system as described above, it has a problem that it depends on temperature.

That is, the ink used in the inkjet printer is added with a solvent having a large molecular weight in order to make the vapor pressure as low as possible.

As a result, the viscosity of the ink liquid often increases at a temperature of 10 ° C. or lower.

When the viscosity of the ink increases, it becomes impossible to eject from a thin ejecting nord, which causes ejection failure.

Therefore, conventionally, a structure has been proposed in which the viscosity of the ink is prevented from increasing even at a low temperature by heating the vicinity of the head or the inside of the printer.

However, since the vicinity of the head and the inside of the printer have extremely large heat capacities, it takes a long time and a large amount of energy to heat them to obtain a constant temperature, resulting in an increase in cost.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, has a simple structure and is easy to manufacture, and can detect whether or not the amount of ink in the ink chamber is a predetermined amount and a small amount of energy. An object of the present invention is to provide an inkjet printer capable of heating ink in a short time.

To achieve this object, according to the present invention, an ink ejection heating element, an ink ejection port corresponding to the ink ejection heating element, and an ink chamber communicating with the ink ejection port are arranged on a substrate. In the ink jet printer using the recording head described above, when the temperature of the ink in the ink chamber is equal to or lower than a predetermined value, a control unit that heats the ink discharge heating element to a temperature that does not discharge the ink, and the control unit controls the ink Temperature detecting means for transmitting temperature information according to the temperature of the ink chamber, and ink amount detecting means for detecting whether or not the ink amount in the ink chamber is a predetermined amount, the temperature detecting means and the ink amount detecting means. Are provided on the same substrate.

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

FIG. 1 and the following figures illustrate an embodiment of the present invention, and FIG. 1 shows the details of the ink supply system.

The ink supply system includes a recording head 1, a pump 9, an ink cartridge 18, and a controller 23 that controls each part.

The details of each part are as follows.

The recording head 1 is composed of a substrate 1e and a cover 38, which are two parts, as shown in FIGS. 2 and 3A and 3B.

The cover 38 is formed as a flat housing with one side open, and along this open end are formed the injection nozzles 1a formed as a plurality of grooves, and the ventilation nozzles 1b also formed as grooves are formed. Has been formed.

The ejection nozzle 1a and the ventilation nozzle 1b communicate with the ink chamber 1c which occupies the center of the cover 38.

Further, an ink passage 39 is formed on the other side of the ink chamber 1c, the upper end thereof communicates with the ink chamber 1c via a passage 39b, and the lower end thereof to the pump side described later via a small hole 39a. Connected with.

The reference numeral 40 in FIG. 3 (B) indicates a ventilation nozzle 1b.
When the ink is supplied into the ink chamber 1c through the opening 40 with respect to the ink chamber 1c, the ink is discharged from the ventilation nozzle 1b.

On the other hand, on the side of the substrate 1e, a plurality of heating elements 1h as heating elements for ejecting ink are formed at positions corresponding to the ejection nozzles 1a, and liquid level level detection is performed at a certain vertical distance. An electrode 1f and a temperature detecting element (for example, a thermistor) 1g are arranged, and these are led out to the rear end side of the substrate 1e by the lead electrodes S0 to S8, respectively.

The above-mentioned heating element 1h, level detection electrode 1f, temperature detection element
The material 1g can be extremely easily formed on the substrate 1e by a thin film forming means such as vapor deposition or sputtering.

The substrate 1e having the above structure and the cover 38 are integrated in a state in which the jet nozzle 1a and the heating element 1h are superposed.

Then, the cover 38, which is open on one side, is closed by the substrate 1e.

Of course, the level detection electrode 1f, the temperature detection element 1g and the like may be separately formed and provided on the substrate 1e by bonding or other means.

The electrodes S0 and S1 of the recording head 1 having such a structure
When a predetermined pulse voltage is applied as a recording signal between S4 and a predetermined heating element 1h, heat is generated, the ink guided into the ejection nozzle 1a is momentarily expanded, from the tip of the ejection nozzle 1a. It is ejected toward the recording paper.

By the way, the heating element 1h is used not only for ejecting ink, but also for the following purposes.

That is, in order to make the ink used in an inkjet printer have a vapor pressure as low as possible, a solvent having a large molecular weight is used. For this reason, the viscosity of the ink often increases at a temperature of 10 ° C. or lower.

It is conventionally proposed to heat the vicinity of the recording head or the inside of the printer at a low temperature because the increase in the viscosity of the ink causes the ink not to be ejected.

However, it takes an extremely long time and a large amount of energy to heat a portion having a large heat capacity such as the vicinity of the recording head or the inside of the printer to obtain a predetermined temperature.

Therefore, in the present invention, it is possible to lengthen the current such that the heating element 1h is heated to a temperature at which the ink is not ejected, and to heat the portions of the ejection nozzle 1a and the ink chamber 1c with a small amount of energy in a short time. Is configured.

The level detection electrode 1f is connected to the control device 23 via the liquid level detection circuit 20, and the temperature detection element 1g is connected to the control device 23 via the liquid temperature detection circuit 21.

On the other hand, the ink passage 39 blocks the O-ring 4 from the outside air.
Is connected to the head pedestal 3 via.

The head pedestal 3 has a liquid passage 3a connected to the ink passage 39 and a liquid passage 3b continuous with the liquid passage 3a, and a space between them is separated by a filter 3c.

The filter 3c is for removing fine dust in the ink 2, and is constituted by bundling thin glass hollow needles having a diameter of about 20 to 30 .mu.m into a slice. In addition to the role of removing dust, the filter 3c also has the effect of increasing the hydraulic resistance in the liquid passage behind the ejection nozzle 1a when ejecting ink from the ejection nozzle 1a.

On the other hand, a cap 7 is provided corresponding to the recording head 1. The cap 7 is attached so as to be rotatable around a shaft 7b, and can be displaced between a state in which the portion of the injection nozzle 1a is covered and a state in which it is separated from the state.

The cap 7 has an absorber 8 that absorbs ink that leaks or is ejected from the jet nozzle 1a and the ventilation nozzle 1b, and a large number of small holes 7a that are formed on the back surface of the absorber 8 for discharging ink from the absorber. .

On the other hand, the pump 9 is configured as follows.

A motor is provided in a circular space formed in the housing of the pump 9.
A rotor 9a which is rotated by 10 is rotatably attached, and a plurality of rollers 9c are rotatably supported by a rotor 9a via a shaft 9b at equal intervals in the circumferential direction.

Although there is a difference between the circular space of the pump 9 and the inner diameter of the pump 9 and the diameter of the rotor 9a, the roller 9c is configured so as to be able to rotate while being in contact with the inner peripheral surface of the circular space.

The tube 5 is guided between the rotor 9a and the arc wall 9d located above the circular space of the pump 9, and the tube 6 is guided between the arc wall 9e and the rotor 9a on the lower side. .

One end of the tube 5 communicates with the liquid passage 3a on the side of the head receiving base 3, and a hollow needle 16 to be inserted into a rubber stopper of an ink cartridge described later is attached to the other end.

Further, one end of the tube 6 is connected to the cap 7 side, and the other end is connected to the ink cartridge side.

On the other hand, a through hole 9f is formed on the side of the pump 9, and a pin 11 is slidably fitted in the through hole 9f.

The inner end of this pin 11 faces the arc-shaped space side of the pump 9, and the other end side projects outside the pump 9 and contacts the lever 12 a of the microswitch 12.

Therefore, when the rotor 9a rotates and the roller 9c contacts the pin 11, the pin 11 projects in a direction away from the arcuate space, that is, outside the pump 9, pushes the lever 12a, and turns on the micro switch 12. be able to.

Therefore, the micro switch 12 can detect the rotational position of the roller 9c, and by counting this signal, the rotational speed of the rotor 9a can also be detected.

Further, the micro switch 12 and the motor 10 are connected to the control device 23 via a motor drive circuit 22.

On the other hand, the reference numeral 18 denotes an ink cartridge, which is divided into upper and lower spaces 18a and 18b by a partition wall 18c, and the ink bag 13 is accommodated in the upper space 18a side.

This ink bag 13 is made of aluminum foil with a polymer film, for example,
It is formed by laminating nylon or polyethylene and has one end sealed and a pipe 14 and a rubber plug 15 provided at the other end. By inserting the hollow needle 16 of the tube 5 into the rubber plug 15 and inserting the hollow needle 16 into the pipe 14, the ink 2 in the ink bag 13 can be guided to the recording head side through the tube 5.

On the other hand, the ink absorber 17 is accommodated in the space 18b below the ink cartridge 18, and absorbs the waste liquid of the ink sucked through the tube 6.

By the way, the ink cartridge 18 has a structure that can be detachably replaced, and a limit switch 19 for detecting the ink cartridge 18 is provided at a position where the ink cartridge 18 is mounted. By being pushed by the tip of the cartridge 18, the state in which the ink cartridge 18 is completely attached can be detected.

The micro switch 19 is connected to the control device 23.

The control device 23 monitors and controls each part of the ink supply system described above, and includes a cap operation control circuit, an ink liquid level monitor circuit, a liquid temperature control circuit, a pump operation control circuit, a pump operation time control circuit, and a print standby. It is composed of circuits such as a time detection circuit, a power ON detection circuit, a cartridge entry / exit detection circuit, and the like, and can perform the control operation as described later.

On the other hand, FIG. 4 schematically illustrates a mechanical portion of a printer including the ink supply system as described above, and the same portions as those in FIGS. 1 to 3 are designated by the same reference numerals.

Reference numeral 24 in FIG. 4 denotes a carriage, which is slidably fitted on the guide rails 25 and 26. The carriage 24 is connected to a part of a wire 11 stretched endlessly between a pulley 29 fixed to the tip of the output shaft of a motor 28 for driving the carriage and a driven pulley 30, and a guide rail 25, You can move freely along 26.

On the carriage 24, the above-described ink supply system, recording head, etc. are mounted.

Further, reference numerals 32 and 33 are gears for transmitting the rotation of the motor 10, and reference numeral 34 is a motor for operating the cap 7.

On the other hand, the reference numeral 27 is a platen, and this platen 27
The paper 35 is guided along, and the recording paper 35 can be fed in the sub-scanning direction by rotating the platen 27.

Further, a portion indicated by reference numeral 36 is a recording range, and a portion indicated by reference numeral 37 is a home position range of the carriage 24.

Next, the operation of the inkjet printer configured as described above will be described.

First, the ink supply operation will be described.

The control device 23 monitors the liquid level of the ink in the ink chamber 1c in the recording head 1 every time the recording operation for one page is completed via the level detection circuit 20.

When the level detection circuit 20 detects that the ink level in the ink chamber 1c is below a predetermined level, the control device 23 causes the motor drive circuit 22 to rotate the motor 10 to operate the pump 9. Let

When the ink level in the ink chamber 1c reaches the preset level, the pump 9 rotates for a predetermined number of rotations and then stops.

The reason why the pump 9 is rotated by a predetermined number of revolutions in this way is that the electrode is
This is because the volume of ink in the ink chamber 1c above 1f and the amount of ink ejected from the nozzles are additionally supplied.

On the other hand, based on the roller position signal generated from the micro switch generated by the contact between the roller 9c of the pump 9 and the sliding pin 11, the controller 23 causes the roller 9c to move the sliding pin 11 as shown in FIG. Be sure to press and stop at a position where it is not in contact with the tube 5.

In this state, the tube 5 is not crushed by the roller 9c, and the liquid path of the tube 5 is open.

By the way, during the recording operation of the recording head 1, the ink passes through the tube 5 from the ink bag 13 due to the capillary phenomenon due to the surface tension of the ink 2 and the negative pressure in the ink chamber 1c caused by the ejection of the ink from the ejection nozzle 1a. Are supplied into the ink chamber 1c.

On the other hand, when the level detection circuit 20 determines that the ink level is set, the above operation is not performed.

Next, the detection of ink shortage and the recovery operation are performed as follows.

If the controller 23 does not reach the level detection electrode 1f even after performing the above-described ink supply operation for a certain period of time and the level detection circuit 20 does not detect the ink, there is no ink in the ink bag 13. To judge.

Then, the control device 23 informs the ink shortage by means such as turning on a light emitting element (not shown) or generating an alarm sound, and stops the recording operation.

When the ink cartridge 18 is taken out of the apparatus in this state, the micro switch 19 detects that the ink cartridge 18 has been removed and generates a signal thereof.

When an ink cartridge 18 containing a new ink bag is newly installed in the device and inserted into a predetermined position,
The micro switch 19 detects this and generates a signal indicating that the ink cartridge 18 is mounted.

When it is detected that the ink cartridge has been taken out, the control device 23 releases the notification state of ink shortage by light or sound and prohibits the operation of the pump 9.

The reason for prohibiting the operation of this pump is that when the pump 9 is operated without the ink bag at the tip of the hollow needle 16, a large amount of air is sucked into the tube 5 and the air in the liquid passage is completely expelled. Because it becomes difficult.

Therefore, the operation of the pump 9 is performed only when the ink cartridge is mounted.

On the other hand, when the micro switch 19 detects that the ink cartridge is mounted, the control device 23 releases the operation prohibition of the pump 9 by the detection signal and performs the ink supply operation.

Next, the first recovery operation after recording is not performed for a long time will be described.

When the device is turned off and has not been used for a long time, or when the power is turned on but the recording operation has not been performed for a long time, the first print may not be recorded or the recording density may be low. Accidents such as ink splashing and dirt adhering to the recording paper occur.

This is because the viscosity of the ink at the tip of the ejection nozzle is increased due to the evaporation of the solvent of the ink from the tip of the ejection nozzle 1a.

If you have not recorded for a long time like this,
The control device 23 first detects that the recording operation is not performed for a predetermined time, and detects the ink level via the level detection circuit 20. When the ink level has not reached the predetermined level, the ink supply operation described above is performed.

On the other hand, when it is determined that the ink level is at the predetermined level, the pump 9 is rotated a predetermined number of times to prevent it. This is to supply the volume of ink in the ink chamber 1c above the level detection electrode 1f and the amount of ink ejected from the nozzles, as described above in the ink supply operation.

Next, the operation of the cap 7 and the operation of sucking the waste liquid by the cap 7 will be described.

The cap 7 is rotated about the shaft 7b by driving the motor 34 in a position other than the recording operation, that is, in the range of the home position shown by reference numeral 37 in FIG. 2, and covers the entire surface of the ejection nozzle 1a. In this state, it is possible to prevent the solvent of the ink from evaporating from the ejection nozzle 1a and the adhesion of dust to the nozzle surface.

On the other hand, when the cap 7 is fitted, the ink absorbing body 8 absorbs the ink leaking from the ejection nozzle 1a, and further the pump 9 is operated to operate the cap 7
The ink inside is forcibly discharged through the tube 6 into the absorber 17 in the space 18b for storing the waste liquid of the ink cartridge 18.

At the time of operation of the pump at this time, one of the rollers 9c is always in a state of pressing the tube 9,
The waste ink does not flow back from the absorber 17 toward the cap 7.

The specific operation of the cap 7 is as follows.

That is, when the operation of the pump 9 is started as described above, the cap 7 is fitted to the injection nozzle 1a, and when the recovery operation is completed, the operation of the pump 9 is stopped and the cap 7 is separated from the nozzle 1a.

On the other hand, when the recording operation for one page is completed, the recording head 1 returns to the home position, but when the recording head returns to the home position, the cap 7 is fitted to the tip of the ejection nozzle 1a. Immediately before the recording operation for the next page is started, the cap 7 is separated from the ejection nozzle 1a, and the normal recording operation is performed.

By the way, the pump 9 during the recovery operation as described above
When the ink cartridge 18 is not attached during the operation of, the waste liquid is discharged into the apparatus, and therefore the operation of the pump 9 turns on the micro switch 19 and the signal indicating that the ink cartridge 18 is attached is output. Only to.

In this embodiment, as described above, the ink level in the ink chamber on the recording head side is constantly monitored, and when the ink level falls below a predetermined level, the ink supply operation is always performed, and when the carriage is at the home position. When the ink nozzle is always closed by the cap and the recording operation is not performed for a certain period of time, the ink suction recovery operation is performed, so that the ejection nozzle is not clogged.

In addition, in the above-described embodiment, the structure in which the ink supply and the waste liquid suction are performed by the same pump is illustrated, but the ink feeding system and the waste liquid suction system may use separate and independent pumps. Of course.

Effects As is clear from the above description, according to the present invention, an ink ejection heating element, an ink ejection port corresponding to the ink ejection heating element, and an ink chamber communicating with the ink ejection port,
In an ink jet printer using a recording head having a substrate arranged on a substrate, the ink ejecting heating element is heated to a temperature at which ink is not ejected when the temperature of the ink in the ink chamber is a predetermined value or less. Since the ink is used, it is possible to heat the ink in a short time with extremely small energy, and it is possible to prevent an ink non-ejection accident due to an increase in the viscosity of the ink at low temperature. Moreover, since the heating element for ejecting ink is also used as the heater for adjusting the viscosity of the ink, the structure of the recording head is simple and the manufacturing is easy.

Further, according to the present invention, it has a temperature detecting means for transmitting temperature information according to the temperature of the ink to the control means, and an ink amount detecting means for detecting whether or not the ink amount in the ink chamber is a predetermined amount. Since the temperature detecting means and the ink amount detecting means are provided on the same substrate, the structure of the recording head becomes simpler, the structure becomes easier, and the cost can be reduced. .

[Brief description of drawings]

1 to 4 illustrate one embodiment of the present invention.
FIG. 1 is a schematic configuration diagram illustrating an ink supply system, FIG. 2 is a side view of a substrate of a recording head, FIG. 3 (A) is a front view of a recording head cover, and FIG. 3 (B) is a recording head. FIG. 4 is a side view of the cover, and FIG. 4 is a perspective view illustrating a main part of the inkjet printer. 1 ... Recording head, 1a ... Jet nozzle 1c ... Ink chamber, 1e ... Substrate 1f ... Level detection electrode 1g ... Temperature detection element, 1h ... Heating element 2 ... Ink, 5,6 ... Tube 7 ... Cap, 8, 17 ... Absorber 9 ... Pump, 9a ... Rotor, 9c ... Roller 10 ... Motor, 11 ... Sliding pin 12, 19 ... Micro switch 13 ... Ink bag, 18 …… Ink cartridge 20 …… Level detection circuit, 21 …… Liquid temperature detection circuit 22 …… Motor drive circuit, 23 …… Control device

Claims (7)

[Claims] 1. An ink jet printer using a recording head in which an ink ejection heating element, an ink ejection port corresponding to the ink ejection heating element, and an ink chamber communicating with the ink ejection port are arranged on a substrate. When the temperature of the ink in the ink chamber is equal to or lower than a predetermined value, control means for heating the ink discharge heating element to a temperature at which ink is not discharged, and temperature information according to the temperature of the ink are supplied to the control means. A temperature detecting means for transmitting the ink, and an ink amount detecting means for detecting whether or not the ink amount in the ink chamber is a predetermined amount. The temperature detecting means and the ink amount detecting means are provided on the same substrate. Inkjet printer characterized by being provided. 2. The ink amount detecting means is provided in the ink chamber.
Inkjet printer according to item. 3. The ink jet printer according to claim 2, wherein the ink amount detecting means is provided at a position higher than the position of the ink discharge heating element. 4. The ink jet printer according to claim 1, wherein the ink amount detecting means is formed of a predetermined material by a thin film forming means. 5. The ink jet printer according to claim 1, wherein the temperature detecting means is provided in the ink chamber. 6. The ink jet printer according to claim 1, wherein the temperature detecting means is a thermistor. 7. The ink jet printer according to claim 1, wherein the temperature detecting means is formed of a predetermined material by a thin film forming means.