JPH09286121A - Ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the presence of ink by the back electromotive force generated in a piezoelectric element members in a printing head jetting ink by driving the piezoelectric element members. SOLUTION: A drive signal is selectively applied to a plurality of the piezoelectric element members 76 of a printing head 44 to displace the piezoelectric elements members 76 to jet the ink in respective ink jet channels 75. At this time, the magnitude of the back electromotive force generated in other non- driven piezoelectric element members 76 by the pressure propagated through the ink is judged by a discrimination part 60 to detect the presence of ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus that ejects ink onto paper to print.

[0002]

2. Description of the Related Art In a communication device such as a facsimile device or an information processing device such as a personal computer, data such as characters and figures is usually recorded as visual information.
A recording device capable of printing these data on paper is connected. Various recording methods such as an impact method, a heat-sensitive method, and an ink-jet method are adopted for this recording apparatus. In recent years, an ink-jet method which is excellent in quietness and can print on paper of various materials is adopted. Ink-jet recording apparatuses are frequently used.

The above-mentioned ink jet recording apparatus ejects the ink supplied from the ink cartridge to the print head onto the paper while main scanning the print head.
After printing the band, the printing process of sub-scanning one band width of the paper is repeated to print on the entire surface of the paper. Therefore, the ink jet recording apparatus that prints by such an operation is configured so that the ink is contained by loading the foam in the ink cartridge so that the ink supply to the print head can be stabilized and good printing quality can be obtained. Is becoming
The presence or absence of ink is detected by an ink detection mechanism so that defective printing can be prevented by detecting ink shortage.

That is, the ink-depletion detection mechanism of the conventional ink jet recording apparatus is constructed by paying attention to the fact that the ink has conductivity, and is provided on the bottom of the bottom wall or the side wall of the ink cartridge. It is possible to determine the presence or absence of ink by providing a pair of electrodes in contact with ink and comparing the current value when one electrode is energized with the other with a predetermined value in the printer controller of the recording apparatus main body. It has become.

[0005]

However, in the conventional structure in which a current is passed through the ink to detect the ink shortage, the current deteriorates the ink. Therefore, if the ink is used for a long period of time, the deteriorated ink may deteriorate the print quality. There is a problem of decrease. Further, when the ink cartridge is configured to be attachable to and detachable from the recording apparatus main body so that ink can be exchanged in cartridge units, the ink cartridge and the recording apparatus main body are electrically connected to each other by contacting the electrodes. The printer controller is adapted to detect the current value to be applied during the period. Therefore, with such a configuration, the number of electrical contacts and the number of connection cables are increased to realize detection of ink shortage, and as a result, there is a problem that the head unit becomes larger and the cost increases.

The present invention has been made in order to solve such a problem, and it is possible to prevent deterioration of ink due to energization, to accurately detect the presence or absence of ink, and to simplify the structure. It is an object of the present invention to provide an inkjet recording device that can realize low cost.

[0007]

In order to solve the above problems, in the ink jet recording apparatus of the present invention, in claim 1, a plurality of ink ejection channels filled with ink are formed between a plurality of piezoelectric element members. , A common ink supply source is connected to each of the ink ejection channels via a branch path, and a drive signal is selectively applied to each of the piezoelectric element members to displace the piezoelectric element member so that the ink in each of the ink ejection channels is The presence or absence of ink is detected based on the displacement of the print head ejecting ink and the displacement of at least one of the plurality of piezoelectric element members caused by the pressure propagated through the ink. And an ink shortage detection unit that does this. Accordingly, the presence or absence of ink is detected based on the displacement of at least one of the plurality of piezoelectric element members, which is caused by the pressure of the other piezoelectric element member generated by the pressure transmitted through the ink. Since it is not necessary to install an electrode on the ink cartridge or the like and the ink is not energized, it is possible to prevent the ink from being deteriorated by the energization. In addition, since the presence or absence of ink is detected based on the displacement of another piezoelectric element member with respect to the piezoelectric element member that is displaced by the application of the drive signal, it is not necessary to process the drive signal etc. Only with the displacement of the piezoelectric element member, it is possible to accurately detect the ink exhaustion with a simple structure. Further, since it is not necessary to dispose an electrode on the ink cartridge as described above and the presence or absence of ink depletion is detected by the print head and the ink depletion detection means, the electrode is connected to the portion of the head unit that receives the ink cartridge. It is not necessary to newly provide an electric contact or a connecting cable that is used. Therefore, the head unit can be downsized and the cost can be reduced. Further, for example, in the case of an ink jet recording apparatus in which ink is replenished by replacing an ink cartridge, conventionally, accurate presence / absence detection can be performed without paying attention to a connection state with an electrical contact or a connection cable connected to the electrode when the ink cartridge is replaced. Although not done, in the configuration of the present invention, since the ink cartridge is not provided with the electrodes and the electrical contacts as described above, it is possible to easily handle the ink cartridge at the time of replacement.

According to a second aspect of the present invention, in the first aspect, the ink shortage detecting means detects a back electromotive force generated due to the displacement of the other piezoelectric element member. As a result, the counter electromotive force generated along with the displacement of another piezoelectric element is directly input without the need for a device for processing the drive signal applied to the displaced piezoelectric element member, and the comparator etc. The back electromotive force can be detected by using a simple circuit using the comparator, and the ink shortage detection means can be easily realized and the ink shortage can be accurately detected.

In a third aspect of the present invention, according to the second aspect, each of the piezoelectric element members has an electrode to which the drive signal is supplied, and the ink shortage detecting means is at least one.
It is connected to the electrodes of two piezoelectric element members.
Thus, by connecting the ink out means to the electrode for displacing each piezoelectric element member, it is not necessary to separately provide a special electrode, and the electrode for displacing the piezoelectric element member is also used. Therefore, low cost can be realized.

According to a fourth aspect of the present invention, in each of the first to third aspects, each of the piezoelectric element members forms at least a part of a partition wall forming each of the ink ejection channels. is there. As a result, each piezoelectric element member is affected by the presence or absence of ink in each ink ejection channel, and when ink is present in the ink ejection channel, the displacement of the piezoelectric element member ensures that the other piezoelectric element member passes through the ink. When the pressure (pressure wave) is propagated and the ink is not present in the ink ejection channel, the pressure (pressure wave) is not propagated to the other piezoelectric element members. The occurrence of displacement of the member becomes remarkable. Therefore, it is possible to accurately detect the presence or absence of ink depletion by the ink depletion detection means.

According to a fifth aspect of the present invention, in the ink discharge detecting means according to the second aspect, the back electromotive force from the non-driving piezoelectric element member to which the driving signal is not applied at the time of recording operation by driving the print head. A signal for detecting the presence or absence of ink is output based on the electric power. As a result, at the time of recording operation by driving the print head, the driven piezoelectric element to which the drive signal is not applied due to the displacement of the piezoelectric element member to which the drive signal is selectively applied and displaced based on the print data (print signal) Since the member is displaced by receiving pressure (pressure wave) through the ink, no device for driving the piezoelectric element is required to detect the presence or absence of the ink. Also,
Since the piezoelectric element member used for printing is also used, a simple structure and low cost can be realized.

According to a sixth aspect of the present invention, in the second aspect, the ink shortage detecting means applies a drive signal to a predetermined piezoelectric element member during maintenance of the print head, and the drive signal is not applied. Based on the counter electromotive force from the piezoelectric element member, a signal for detecting the presence or absence of ink is output. As a result, at the time of maintenance such as flushing or purging, only a predetermined piezoelectric element member is ejected after or before the ejection failure of each nozzle is prevented by ejecting the ink from all the ink ejection channels or sucking the ink. It is possible to detect the presence or absence of ink in each ink ejection channel by detecting the counter electromotive force in the other piezoelectric element member that is driven and separated by a certain distance from the piezoelectric element member. No need to connect. Therefore, with a simple structure,
It is possible to detect the presence or absence of ink shortage while executing low cost.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An ink jet recording apparatus of the present invention will be described below with reference to FIGS.

The ink jet recording apparatus according to the present invention is
As shown in FIG. 5, it is connected to an information processing device 1 such as a personal computer. The information processing device 1 includes a processing device main body 2 including an auxiliary storage device such as a magnetic disk device and a central processing unit, and a CRT (ca
a printer, which is an inkjet recording device, via a printer cable 6 of, for example, Centronics specification. There is.

As shown in FIG. 6, the processing apparatus main body 2 is equipped with, for example, a window system 8 as an operating system (OS). The window system 8 includes an application 9 such as a document creation program, a font driver 10 for managing fonts, a CRT driver 11 for managing the CRT 3, a keyboard driver 12 for managing the keyboard 4, and a mouse driver 13 for managing the mouse 5. , One or a plurality of applications 9 can be simultaneously executed in cooperation with various functional groups such as a printer driver 14 that manages the printer 7.

The printer driver 14 is capable of forming dot image data when the "print execution" menu is specified for the data displayed on the screen of the CRT 3, for example. Dot data (pixel data arranged in a dot matrix in the horizontal and vertical directions) is formed based on the font data of the text to be displayed, and these dot image data are set in the horizontal direction (raster direction) for each raster. )
Further, the interface (I / F) unit 15 sequentially outputs the print data in units of 8 bits.

The print data output in the raster scan format as described above is input to the I / F (interface) unit 16 of the printer 7, which is an ink jet recording apparatus. The printer 7 is an RA in which a printer controller 17 (ink shortage detection means) and various data areas such as a print buffer area are formed.
M18, ROM 36 in which various control programs such as a printing routine and an out-of-ink detection routine are stored, a head drive unit 19, a CR motor drive unit 20, an LF motor drive unit 33, and various processing operations are instructed. Operation panel 4
6 and a determination unit 60 (ink shortage detection unit) that outputs a low-level determination signal when the ink runs out.

The above-mentioned head drive unit 19 is used for the print head 4
4 is connected. As shown in FIG. 1, the print head 44 includes a piezoelectric substrate 71 made of piezoelectric ceramic that is a piezoelectric element member, an upper cover 72 fixed to the upper surface of the piezoelectric substrate 71, and a nozzle fixed to the front surface of the piezoelectric substrate 71. It has a plate 73 and a printed circuit board 74 fixed to the lower surface of the piezoelectric substrate 71. The piezoelectric substrate 71 includes a plurality of piezoelectric sidewalls 76 (piezoelectric element members) and concave grooves 81 which are formed to be parallel to each other by cutting such as dicing.
Are alternately provided, and the piezoelectric side walls 76 and the recessed grooves 81 are formed by fixing the upper cover to the upper surface of the piezoelectric substrate 71 so that the plurality of ink ejection channels 7 are formed.
5 are formed. A plurality of nozzles 73a ... Corresponding to the respective ink ejection channels 75 ... Are formed on the nozzle plate 73, and these nozzles 73a. The ink in the ejection channels 75 ... Is pressurized and ejected. Further, the upper cover 72 is formed with a through-hole 78, and an ink supply groove 85 (branch groove) is formed continuously with the through-hole 78 to connect the ink ejection channels 75. . The through-holes 78 communicate with the ink ejection channels 75 through the ink supply grooves 85 and the ink cartridge 30 of FIG. 7 (ink supply source common to the ink ejection channels 75 ...), so that the ink ejection channels 75. The ink of the ink cartridge 30 is filled into each ink ejection channel 75 through the ink supply groove 85 when the volume of the ink cartridge is restored.

The piezoelectric side walls 76 forming the ink ejection channels 75 are polarized in the arrow B direction. As shown in FIG. 2, electrodes 77 are formed on the upper portions of both side surfaces of each of the piezoelectric sidewalls 76 by plating, for example. This electrode 77, as shown in FIG.
Are connected to a plurality of electrode terminals 79 formed on the printed circuit board 74 via wires 80. The electrode terminals 79 ... Are connected to the head drive section 19, and the head drive section 19 selectively applies a drive signal (voltage) to the electrode 77 based on the print data, and the piezoelectric side wall 7 is formed.
6 (piezoelectric element member) is sheared (displaced) to reduce the volume of each ink ejection channel 75.

The electrode terminals 79 (piezoelectric side walls 76) formed on the printed circuit board 74 are connected to the determination section 60 via signal lines 86. The determination unit 60 is shown in FIG.
As shown in FIG. 3, an amplifier 62 that amplifies the counter electromotive force generated on the piezoelectric sidewalls 76 (piezoelectric element member), a rectifier circuit 63 that rectifies the amplified product, and a rectified voltage from the rectifier circuit 63 as a reference voltage. And a comparator circuit 64 that outputs a low-level determination signal when the rectified voltage is smaller than the reference voltage. In addition, the determination unit 60
Has a plurality of switches 65 ... Which can be switched so that the electrode terminals 79 ... (Piezoelectric side walls 76 ...) And the amplifier 62 of the determination unit 60 are connected / disconnected in each signal line 86. ,
Each switch 65 can be switched depending on the presence or absence of a print timing signal output from the printer controller 17 via a plurality of inverters 66 ... That is, each switch 65 outputs the print timing signal output from the printer controller 17 to each inverter 66 ...
Is input, the electrode terminal 79 (piezoelectric side wall 76) to which the drive signal (power) is applied corresponding to the output of the print signal and the amplifier 62 of the determination unit 60 are not connected, and the print timing signal is output. When each inverter 66 ... Does not input, each electrode terminal 79 ... (Piezoelectric side wall 76 ...) is switched so as to be connected to the amplifier 62 of the determination unit 60.

The determination signal 60 of the comparator circuit 64 is
As shown in FIG. 6, the data is output to the printer controller 17. Printer controller 17
Is connected to the RAM 18 and the ROM 36 described above so as to be accessible. And the printer controller 1
7 executes the program stored in the ROM 36 and RA
A print operation (recording operation) is performed by executing print data write processing and read processing for the print buffer area of M18. In addition to the printing operation, an ink depletion detection routine is interrupted during printing, and ink depletion is detected based on the determination signal from the determination unit 60. The printer controller 17 is also connected to the CR motor drive unit 20 and the LF motor drive unit 33. CR motor drive unit 20 and LF
The motor drive unit 33 is connected to the CR motor 22 used for main scanning and the LF motor 34 used for sub scanning, respectively, and controls the rotation directions and speeds of the motors 22 and 34. .

The print head 44 controlled by the printer controller 17 is included in the print head mechanism 21 as shown in FIG. The print head mechanism 21 includes a cartridge holding member 31, an ink supply member 37 provided on the cartridge holding member 31, and a cartridge holding member 3.
1 and an ink cartridge 30 serving as an ink supply source detachably provided. The print head 44 described above is provided at the front of the ink supply member 37. The print head 44 and the ink cartridge 30 are detachable via the cartridge holding member 31.

Inside the above-mentioned ink cartridge 30, a foam 35 having open cells containing ink is loaded. An ink supply port 30a is formed in the lower portion of the front wall of the ink cartridge 30, and the above-described ink supply member 37 is fitted in the ink supply port 30a in a liquid-tight state via a seal member 39. ing. The ink supply member 37 has an ink introduction hole 3 that connects the print head 44 to the inside of the ink cartridge 30.
7a is formed, and the ink introduction hole 37a supplies the ink of the ink supply member 37 to all the ink ejection channels 75 of the print head 44.

The print head mechanism 2 constructed as described above
As shown in FIG. 8, 1 is fixed to the carriage 23 such that the ink ejection direction is at a predetermined angle with respect to the paper P (recording medium). The carriage 23 is movably supported by a guide shaft 24 provided laterally in the main scanning direction X, and reciprocates the carriage 23 in the main scanning direction X along a scanning belt 25 driven by the CR motor 22. As a result, the print head mechanism 21 is configured to perform main scanning while maintaining a constant distance from the paper P.

The sheet P facing the print head mechanism 21 is supported by a platen roller 28. The platen roller 28 is provided parallel to the guide shaft 24, and both ends thereof are rotatably supported. A platen gear 29 is fixed to one end of the platen roller 28. The platen gear 29 is connected to the LF motor, and the LF motor rotates the platen roller 28 to move the sheet P in the sub-scanning direction Y. The movement of the paper P in the sub-scanning direction Y is repeated each time the print head mechanism 21 is main-scanned to print one band.

A maintenance mechanism RM including a flash ink absorber 47, a purging device 48, and a wiping device 49 is arranged at a position outside the printing area on the platen roller 28. The flash ink absorber 47 is arranged on the left side of the platen roller 28. The flash absorber 47 faces the nozzles 73a of the print head 44 of the print head mechanism 21 which is main-scanned by the drive of the carriage 23, and corresponds to all the ink ejection channels 75 during the flash process.
It absorbs the ink ejected from. On the right side of the platen roller 28, a purging device 48 that sucks ink in the print head 44, a wiping device 49 that wipes the ejection surface of the print head 44, and the like are provided. The ink jet print head 44 causes defective ink ejection due to, for example, bubbles generated inside during use or ink droplets adhering to the ejection surface. To do so.

In the above arrangement, the printer controller 17 executes the ink shortage detection routine during the printing operation by driving the print head 44. That is, first, as shown in FIG. 1, when a pulsed print signal (print data) is output from the printer controller 17 to the head drive unit 19 and the determination unit 60, the ink shortage detection routine is executed by interruption. Head drive unit 19
When the print timing signal is input from the printer controller 17 after the print data is temporarily stored, the ink ejection channel 75 corresponding to the print data is
A square-wave drive signal (voltage) is applied to the electrode terminal 79 (piezoelectric side wall 76) of. Further, since the corresponding inverter 66 inputs the print timing signal from the printer controller 17, each switch 65 ...
The other electrode terminal 79 to which the drive signal (power) is not applied is connected without connecting only the electrode terminal 79 (the piezoelectric side wall 76 to be driven) to which the drive signal (power) is applied (non-drive piezoelectric side wall 76). To be connected.

As shown in FIG. 3, in the ink ejection channel 75a on which the drive signal (voltage) is printed by the head drive section 19, the voltage V is applied to the electrode 77a and the GND potential is applied to the electrode 77b. Therefore, an electric field indicated by an arrow C is generated on the voltage side wall 76, and as a result, the piezoelectric side wall 7 is formed.
6 undergoes shear deformation (displacement), and ink ejection channel 75a
Will be reduced in volume.

At this time, each ink ejection channel 75 ...
When the volume of the ink ejection channel 75a is reduced in the presence of ink in the ink ejection channel 7
Since the pressure of the ink with which 5a is filled rapidly rises and a pressure wave is generated, this pressure wave is propagated through the ink to the other non-driven piezoelectric side walls 76 ... Which are communicated with the ink supply groove 85, These non-driven piezoelectric side walls 76 ... Deform.
Due to this deformation, the electrodes 77a and 77b on the non-driven piezoelectric side walls
A back electromotive force is generated between and. Further, when the ink in the ink ejection channel 75a is pressurized, the ink is ejected from the nozzle 73a of the nozzle plate 73 arranged in front of the ink ejection channel 75a, and the application of the drive signal (voltage) is completed. , The piezoelectric side wall 76 is released from the deformed state (displaced state), and the ink ejection channel 7
While the volume of 5a is restored, the ink cartridge 30
Ink is supplied into the ink ejection channel 75a.

Thereafter, the piezoelectric side wall 76 which is not driven as described above is used.
As shown in FIG. 4 or FIG. 6, the counter electromotive force generated in
When it is taken into the determination unit 60, it is amplified and rectified in the amplifier 62 and the rectifier circuit 63, respectively. Then, this rectified voltage is output to the comparator circuit 64,
The comparator circuit 64 determines that the input signal is equal to or higher than the reference voltage, and outputs a high level determination signal.

The above determination signal is taken in by the printer controller 17 as shown in FIG. 4 or 6. Then, the printer controller 17 detects the presence of ink based on the determination signal,
The ink shortage detection routine is ended.

On the other hand, when the drive signal (voltage) is applied to the electrode 77 and the ink in each ink ejection channel 75 becomes low, the ink ejection channel 75a
Even if the piezoelectric side wall 76 of (1) is sheared (displaced) and the volume of the ink ejection channel 75a is reduced, the air in the ink ejection channel 75a is compressed and contributes almost to the pressure rise of the ink. The pressure (ink pressure wave) is not propagated to the non-driven piezoelectric side walls 76 ... As a result, the non-driving piezoelectric side walls 76 ... Are hardly deformed, so that almost no counter electromotive force is generated between the electrodes 77a and 77b of the non-driving piezoelectric side walls 76. This phenomenon is caused by the ink ejection channel 75.
The more the amount of the ink in the inside becomes small, the more remarkable it becomes, and the counter electromotive force generated between the electrodes 77a and 77b of the non-driving voltage side walls 76 ...

Thereafter, the piezoelectric side wall 76 which is not driven as described above is used.
As shown in FIG. 4, the back electromotive force generated in
When it is taken into 0, it is amplified and rectified in the amplifier 62 and the rectifier circuit 63, respectively. Then, this rectified voltage is output to the comparator circuit 64, and the comparator circuit 64 determines that the input signal is equal to or lower than the reference voltage, and outputs a low-level determination signal.

The above determination signal is fetched by the printer controller 17 as shown in FIG. 4 or 6. Then, the printer controller 17 detects the ink shortage based on the determination signal to display or inform the operation panel 46 of the ink shortage, and after stopping the printing operation, the ink shortage detection routine is performed. Will end.

In the ink jet recording apparatus of the present invention, the judging section 60 is not limited to the one shown in FIG. 4, but may have the structure shown in FIG. In this case, as shown in FIG. 9, the determination unit 60 includes an amplifier 62 that amplifies counter electromotive force generated by pressure (ink pressure wave) propagated to the non-driven piezoelectric sidewalls 76 ... (Piezoelectric element member). A rectifying circuit 63 for rectifying the amplified one,
A comparator circuit 64 that compares the rectified voltage from the rectifier circuit 63 with a reference voltage and outputs a low-level judgment signal when the rectified voltage has a value smaller than the reference voltage; a judgment signal from the comparator circuit 64; When the print timing signal output from the controller 17 via the inverter 66 is input, the printer controller 17
An AND circuit 67 that outputs a determination signal to

As a result, the determination unit 60 causes the piezoelectric side wall 76 to
Based on the counter electromotive force generated by the deformation caused by the pressure (ink pressure wave) propagated through the ink to the other non-driven piezoelectric sidewalls 76 only when the ... Is driven and sheared (displaced). The presence / absence of ink in each ink ejection channel 75 can be detected, and the presence / absence of ink can be detected more accurately without depending on the back electromotive force generated by being deformed due to other causes.

Further, in the ink jet recording apparatus of the present invention, the presence or absence of ink in each ink ejection channel 75 is detected during the printing (recording) operation by driving the print head 44, but the present invention is not limited to this. Not something
The presence or absence of ink may be detected during maintenance such as flashing or purging of the print head 44. In this case, the determination unit 60 uses the one shown in FIG. As shown in FIG. 10, the determination unit 60 is connected to the electrode terminal 79 of one non-driven piezoelectric side wall 76, and the pressure (pressure wave of ink) propagated to the non-driven piezoelectric side wall 76 is determined. ), And an rectifier circuit 6 for rectifying the amplified product.
3 and a comparator circuit 64 that compares the rectified voltage from the rectifier circuit 63 with a reference voltage and outputs a low-level determination signal when the rectified voltage has a value smaller than the reference voltage. Here, the flushing process in FIG. 8 refers to the print head 4 in order to prevent ink unevenness or the like ejected from the nozzles 73a of the print head 44 onto the paper P in FIG.
No. 4 is to eject the ink from the all ink ejection channels 75 ... to the flash absorber 47 every main scanning a predetermined number of times or every predetermined time, and the purging process is the print head. When the printing by the print head 44 is started, in order to prevent ejection failure of the nozzles 73a ... Due to air remaining in the nozzles 73a.
4 is sucked (purged) a plurality of times to discharge the air.

When the print head 44 is subjected to flash processing, as shown in FIG. 8, the print head 44 is moved in the main scanning direction X to face the absorber 47 for flash, and then the head drive unit 19 is operated. Drive signals (electric power) are printed on all the piezoelectric side walls 76 (all piezoelectric element members) from all the ink ejection channels 75 ... Ink is ejected to 47.

After that, by applying a drive signal (voltage) to the piezoelectric side wall 76 (piezoelectric element member) connected to the judging section 60, the piezoelectric side wall 76 of another ink ejection channel 75a having a certain distance. Ink ejection channel 75
Reduce the volume of a. Then, as the volume of the ink ejection channel 75a decreases, the pressure (ink pressure wave) propagated through the ink to the one non-driving piezoelectric side wall 76 connected to the determination unit 60 as described above. By deforming and comparing the counter electromotive force generated by this deformation with the comparator circuit 64 of the determination unit 60, the presence or absence of ink in each ink ejection channel 75 ... Is detected by comparing with the reference voltage value.

Also, when purging the print head 44, all the nozzles 73a of the print head 44 are set in the same manner as in FIG.
After the air is exhausted by the purging device 48 shown in FIG. 2, a drive signal (voltage) is applied to the piezoelectric side wall 76 of the ink ejection channel 75a different from the piezoelectric side wall 76 (piezoelectric element member) connected to the determination unit 60. Is applied to reduce the volume of the ink ejection channel 75a. Then, as the volume of the ink ejection channel 75a decreases, the pressure (ink pressure wave) propagated through the ink to the one non-driving piezoelectric side wall 76 connected to the determination unit 60 as described above. By deforming and comparing the counter electromotive force generated by this deformation with the comparator circuit 64 of the determination unit 60, the presence or absence of ink in each ink ejection channel 75 ... Is detected by comparing with the reference voltage value.
The ink detection operation may be performed before the flush processing and the purge processing.

Thus, during maintenance such as flushing and purging of the print head 44, ink is ejected from all the ink ejection channels 75 ... And ink is sucked to prevent ejection failure of the nozzles 73a. Before that, by driving only one piezoelectric side wall 76 and detecting a back electromotive force in one non-driving piezoelectric side wall 76 which is away from it by a certain distance, each ink ejection channel 75 is detected.
Since it is possible to detect the presence or absence of ink inside the ..., It is not necessary to connect the determination unit 60 to all the piezoelectric side walls 76. Therefore, as compared with the method of detecting the ink shortage during the printing operation of the print head 44, the configuration of the determination unit 60 can be simplified, and the presence or absence of the ink shortage can be detected while executing the low cost.

[0042]

As described above, according to the ink jet recording apparatus of the present invention, in claim 1, a plurality of ink ejection channels filled with ink are formed between the plurality of piezoelectric element members, and each ink ejection channel is formed. A print head that connects a common ink supply source through a branch path, selectively applies a drive signal to each piezoelectric element member, and ejects ink in each ink ejection channel by displacement of the piezoelectric element member. An out-of-ink detecting means for detecting the presence or absence of ink based on the displacement of at least one of the plurality of piezoelectric element members caused by the pressure propagating through the ink. I have. Accordingly, the presence or absence of ink is detected based on the displacement of at least one of the plurality of piezoelectric element members, which is caused by the pressure of the other piezoelectric element member generated by the pressure transmitted through the ink. Since it is not necessary to install an electrode on the ink cartridge or the like and the ink is not energized, it is possible to prevent the ink from being deteriorated by the energization.
Further, the piezoelectric element member that is displaced by the application of the drive signal,
Since the presence or absence of ink is detected based on the displacement of the other piezoelectric element member, it is possible to accurately and accurately with a displacement of the other piezoelectric element member without the need of processing a drive signal or the like. Can detect ink shortage. Furthermore, since it is not necessary to dispose an electrode in the ink cartridge as described above, and the presence or absence of ink depletion is detected by the print head and the ink depletion detection means, the electrode is connected to the portion of the head unit that receives the ink cartridge. It is not necessary to newly provide an electric contact or a connecting cable that is used. Therefore, the head unit can be downsized and the cost can be reduced. Further, for example, in the case of an ink jet recording apparatus in which ink is replenished by replacing an ink cartridge, conventionally, accurate presence / absence detection can be performed without paying attention to a connection state with an electrical contact or a connection cable connected to the electrode when the ink cartridge is replaced. Although not done, in the configuration of the present invention, since the ink cartridge is not provided with the electrodes and the electrical contacts as described above, it is possible to easily handle the ink cartridge at the time of replacement.

According to a second aspect, in addition to the one according to the first aspect,
The ink shortage detection means detects a back electromotive force generated due to the displacement of the other piezoelectric element member.
As a result, in addition to the effect of the first aspect, the counter electromotive force generated with the displacement of another piezoelectric element can be obtained without requiring a device for processing the drive signal applied to the displaced piezoelectric element member. It becomes possible to directly detect the back electromotive force by using a simple circuit that uses a comparator such as a comparator. Can be detected.

In a third aspect of the present invention, according to the second aspect, each of the piezoelectric element members has an electrode to which the drive signal is supplied, and the ink shortage detection means is an electrode of at least one piezoelectric element member. Is connected to. Thus, in addition to the effect of the second aspect, by connecting the ink shortage means to the electrode for displacing each piezoelectric element member, it is possible to displace the piezoelectric element member without the need to separately provide a special electrode. Since it also serves as an electrode, a simple structure and low cost can be realized.

According to a fourth aspect of the present invention, in each of the first to third aspects, each of the piezoelectric element members forms at least a part of a partition wall forming each of the ink ejection channels. . As a result, in addition to the effects of each of claims 1 to 3, each piezoelectric element member is affected by the presence or absence of ink in each ink ejection channel,
When ink is contained in the ink ejection channel, pressure (pressure wave) is surely propagated to the other piezoelectric element member through the ink by displacement of the piezoelectric element member, and when there is no ink in the ink ejection channel, another piezoelectric element member Since no pressure (pressure wave) is propagated to the other side, the presence or absence of displacement of other pressure element members becomes significant depending on the presence or absence of ink in the ink ejection channel. Therefore, with the ink out detection means,
It is possible to accurately detect the presence or absence of ink shortage.

According to a fifth aspect of the present invention, in the ink exhaustion detecting means according to the second aspect, the back electromotive force from the non-driving piezoelectric element member to which the driving signal is not applied at the time of recording operation by driving the print head. A signal for detecting the presence or absence of ink is output based on the electric power. As a result, in addition to the effect of claim 2, when the recording operation is performed by driving the print head, the piezoelectric element member is driven by the displacement of the piezoelectric element member which is selectively applied with the drive signal based on the print data (print signal). Since the driven piezoelectric element member to which no signal is applied receives pressure (pressure wave) through the ink and is displaced,
Since a piezoelectric element member used for printing is also used without requiring a device for driving the piezoelectric element to detect the presence or absence of ink, a simple structure and low cost can be realized.

According to a sixth aspect of the present invention, in the second aspect, the ink shortage detecting means applies a drive signal to a predetermined piezoelectric element member at the time of maintenance of the print head, and the drive signal is not applied. Based on the counter electromotive force from the piezoelectric element member, a signal for detecting the presence or absence of ink is output. As a result, in addition to the effect of claim 2, during maintenance such as flushing and purging, ink is normally ejected from all ink ejection channels, or ink is aspirated to prevent ejection failure of each nozzle or before. In addition, it is possible to detect the presence or absence of ink in each ink ejection channel by driving only a predetermined piezoelectric element member and detecting the back electromotive force in the piezoelectric element member that is not driven a certain distance from the piezoelectric element member. It is not necessary to connect the ink out detection means to the element member. Therefore, with a simple structure, it is possible to detect the presence or absence of ink shortage while executing low cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a connection state between a print head and a determination unit.

FIG. 2 is a cross-sectional view showing a state of the print head before application of a drive signal.

FIG. 3 is a cross-sectional view showing a state of the print head after application of a drive signal.

FIG. 4 is a block diagram of a determination unit.

FIG. 5 is a perspective view of an inkjet recording apparatus connected to an information processing apparatus.

FIG. 6 is a block diagram of a control system of the inkjet recording apparatus.

FIG. 7 is a cross-sectional view of an ink cartridge.

FIG. 8 is a perspective view of a main part of the inkjet recording apparatus.

FIG. 9 is a block diagram of a determination unit according to a first modified example.

FIG. 10 is a block diagram of a determination unit according to a second modified example.

[Explanation of symbols]

 17 Printer Controller (Ink Depletion Detection Unit) 30 Ink Cartridge (Ink Supply Source) 60 Judgment Unit (Ink Depletion Detection Unit) 75 Ink Jet Channel 76 Piezoelectric Sidewall (Piezoelectric Element Member) 90 Branch Groove

Claims (6)

[Claims] 1. A plurality of ink ejection channels filled with ink are formed between a plurality of piezoelectric element members, and a common ink supply source is connected to each of the ink ejection channels via a branching path. A print head that selectively applies a drive signal to the member to eject the ink in each ink ejection channel by the displacement of the piezoelectric element member; and at least one displacement of the plurality of piezoelectric element members through the ink. An ink-jet recording apparatus, comprising: an ink-out detection unit that detects the presence or absence of ink based on the displacement of another piezoelectric element member generated by the pressure transmitted by the ink. 2. The ink jet recording apparatus according to claim 1, wherein the ink depletion detection unit detects a back electromotive force generated due to the displacement of the other piezoelectric element member. 3. The piezoelectric element member has an electrode to which the drive signal is supplied, and the ink shortage detection means is connected to an electrode of at least one piezoelectric element member. Item 2
The inkjet recording apparatus according to any one of the preceding claims. 4. The ink jet recording apparatus according to claim 1, wherein each of the piezoelectric element members forms at least a part of a partition wall forming each of the ink ejection channels. 5. A signal for detecting the presence or absence of ink, based on a back electromotive force from a non-driving piezoelectric element member to which the driving signal is not applied, during the recording operation by driving the print head. The inkjet recording apparatus according to claim 2, wherein 6. The ink shortage detection means applies a drive signal to a predetermined piezoelectric element member during maintenance of the print head, and based on a back electromotive force from another piezoelectric element member to which the drive signal is not applied. The ink jet recording apparatus according to claim 2, wherein a signal for detecting the presence or absence of ink is output.