OA19099A - Inkjet print head device and a method and system for detecting ink leakage. - Google Patents

Abstract

The present invention relates to an inkjet print head device for continuous inkjet printing, comprising a transducer; a charge electrode; a deflection plate; a gutter; and a holster; provided that the holster is receiving at least the aforementioned components, wherein the holster comprises an opening for a dedicated outlet for the ink in a printing mode, and wherein the holster further comprises an ink leakage detection area. Further the invention relates to a method and a system for detecting ink leakage in a print head.

Description

Inkjet print head device and a method and system for detecting ink leakage

Technical Field

The présent invention relates to an inkjet print head device and a method for detecting ink leakage.

Background of the Invention tO-----------------------------------------------------------------------In continuous ink jet printing dots with a size of about 7 0um of size will be travelling at a high speed from an orifice to a gutter in standby printing mode. A gutter is a kind of a return pipeline, for collecting the ink exiting in standby 15 mode.

Upon printing the dots passing are deflected via charge électrodes and a high voltage deflection plate to form a printing pattern based on object's movement speed. The ink 20 dots misaligned from entering the gutter or deflected far away from the holster's exit path will build up as waste and accumulât ing in a holster cover and finally drip on the product and/or conveyor causing unfavorable stains.

Ail this will be undetected until physical notice by a human or a vision inspection system

Some ink leakage détection Systems are known in the prior art, which refer to leakage détection in the ink supply System (US

8,864,275B2, US 6,402,277B1, EP 1 812 239B1). Further to that ink leakage détection is known from US 6,431,678B2, where ink leakage is detected on the print head substrate. [

Further to that, in printing with security inks, there is a | i i threat of stealing the via tweaking the present security ink by unauthorized users by the print head. Accordingly, it is an invention to provide a printing head siphoning object of that includes a mechanism that detects when a) ink has escaped its confined space and b) abnormal security situation has occurred.

Problems to be solved by the present invention

11) The present invention aims at designing a continuous ink jet print head device that is able to detect ink leakage.

Further, the present invention aims to design continuous ink jet print head device to minimize unauthorized ink siphoning.

a suitable the risk of

Summary

The above mentioned problems and drawbacks concepts are solved by the subject-matter of the present invention.

Detailed Description

According to one aspect, the invention of the conventional of the embodiments suggests an inkjet kage—in—continuous----inkjet printing, comprising a transducer, a charge electrode, a deflection plate, a gutter and a holster, provided that the holster is receiving at least the aforementioned components 30 and wherein the holster comprises an opening for outlet for the ink in a printing further comprises an ink leakage a dedicated

The ink leakage détection area mode, and wherein détection area.

comprised by the the holster holster is preferably designed to detect ink leak from the print head of a continuous ink jet printer.

According to a preferred embodiment of the invention the ink leakage détection area is at least provided inside the holster and in a zone neighboring the outlet of the holster.

In yet a further preferred embodiment according to the invention, the ink leakage détection area is a pad.

⁼

The pad preferably covers at least a part of a holster component.

According to a preferred embodiment of the invention the holster further receives a charge driver, an ink supply, an 15 ink pump, and/or a driver.

Preferably the ink leakage détection area comprises a nonconductive substrate and conductive circuit provided thereon.

Further, to yet another aspect it is further suggested a system for detecting ink leakage in a print head for continuous inkjet printing, comprising a print head device as describer, a sensor controller, operatively connected to the ink leakage détection area and a main controller for monitoring the signais from the sensor.

According to a preferred embodiment the system according to the invention further comprises a sensor for detecting unauthorized manipulation of the holster.

This sensor can create for example a signal, that the holster is connected.

According to another aspect the invention describes a method for detecting ink leakage providing a signal from a leakage détection area of a holster of a print head device, a signal referring about the status of the holster, a signal referring about a wiring connection, whereas the signais are sent to a sensor controller and further to a control cabinet.

According to a preferred embodiment an indication by the sensor controller if leakage is detected, not properly closed and/or wiring is not correct,

The indication could for example be an appearance on a screen and/or one or several lights, preferably LED.

is provided holster is is sensed.

According to a preferred embodiment of the invention the printing provided leakage wiring is not connected, is sensed.

process is stopped, as by the sensor control1er is detected, holster is soon as an indication is to the control cabinet that properly closed and/or not is possible that the stopped, as soon as an indication is cabinet that leakage is detected, closed and/or wiring is not correct, is detected.

Additional production process is received by the control holster is not properly

Définitions

A sensor controller circuits converting the receive signais from a ink leak pad to a digital signal as output to a PLC and according to a preferred embodiment gives indication by a lamp, the activated output.

as a LED for

A control cabinet as used in this description a SCL cabinet which hosts the PLC and preferably PC program as a human machine interface.

is simiiar to a touch panel

A PLC is used for a Digital & Analogue signal processor for a low level program.

In this description JAVA is used as a high level program inside a touch panel which interacts with a PLC, a printer, caméra etc. and commands the peripheral input and output directly or via the PLC.

Short description of the drawings

The présent invention will be described for the sake of better understanding by way of exemplary embodiments. These embodiments may be best understood by taking the following drawings in considération. In these Figures,

Figure 1 shows a schematic view of a continuous inkjet printing system, as known from the prior art;

Figure 2 shows a schematic view of a continuous inkjet printing system according to a preferred embodiment of the invention;

Figure 3 shows a schematic of a holster a) according to prior art and b) according to an embodiment of the invention;

Figure 4 shows a schematic view of the a) ink leakage pad and of the extended holster with a slot according to further embodiments of the invention;

Figure 5 shows a detailed view of an ink leak sensing pad from both sides according to a preferred embodiment of the invention;

Figure 6 is an exemplary schematic design of an electrical circuit used in the sensor controller; and

Figure 7 shows a schematic design of an exemplaryi connection between sensor controller and PLC according to ai preferred embodiment of the invention.i !

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Description of preferred embodiments

Figure 1 is a schematic view of a known continuous inkjet printing system (1) including a printer (2) , a PLC (Programmable Logic Controller) (3) and printer head. The PLC (3) and the printer (2) are located in a printer security cabinet (4) . The print head holster (6) is connected via a umbilical cord (5) for marking a product (7) on a product conveyor (8).

A schematic overview of a printing system according to a preferred embodiment of the invention is shown in Figure 2. For éléments corresponding to the éléments of Figure 1 the same reference numerals are used. According to Figure 2 it is 15 proposed to include a print head, modifîed compared to the print head in Figure 1, to host a sensing leak pad (9) . The holster (6) is hold by a print head holder (26) connected to a sensor controller (10), also called sensor box, via a signal cable (11) wherein the sensor controller (10) amplifies and 20 processes an input signal and activâtes a notification device (12), such as a Visual or an audible alert device. The sensor controller (10) also generates and sends three digital input signais to the PLC (3) via an output cable (13) wherein the PLC (3) will enable the printer controller to shut down the 25 operation of printing system if abnormal and/or.....a leakage détection situation is detected.

The expressions three digital input signais and abnormal situation will be explained in details further below.

In Figure 3a) a schematics of a holster (6) according to an embodiment of the prior art is shown. The holster incorporâtes a transducer (14) connected to a driver (17), a charge electrode (15) connected to a charge driver (18) and a deflection plate (16) . The holster (6) comprises an opening (19) for the ink (20) to exit the holster (6) to be printed on an object (21) in motion in direction (22). In the holster (6) is further provided a gutter (23) to collect the ink exiting the print head in stand-by mode. From the gutter (23) the ink (20) is guided to a collecter (24) from where the ink is guided to a pump (25).

A schematic holster (6) according to an embodiment of the invention is shown in Figure 3b) . As can be seen from tiie comparison of Figure 3a) and 3b) , the holster (6) is extended to enable a leak détection pad to be inserted in the holster (6) . The extension x in this example is about 2 mm, and preferably is in the range of 1.6mm to accommodate a leak 15 détection pad.

Figure 4 shows a schematic view of the a) ink leakage pad (9) and b) part of the extended holster (6) with a slot (27) and the mounted holster assembly, i.e. the print head holder (26) 20 according to further embodiments of the invention. The cylindrical holster (6) connects to the print head by slotting in and lock-pin-release button.

The exemplary sensing leak pad (9), shown in Figure 5, is a made of a non- conductive substrate (28) with loop like tracks (29) which are according to this embodiment of the invention formed of Tantalum. It could be also formed of other like conductive material that coated with lead free silver to comply with RoHS and CE certified substance.

A power line, +24 VDC is coupled to one of the conductive tracks (29) via a pin 2 (30b) and a returning conductive track that senses the leaked current is coupled to pin 3 (30c) . In case of leakage, the ink conductivity bridges between these track lines (29) and electrically interconnects them thus a signal current is sent to the sensor controller (10) to be processed and send an ink leak signal output signal to the

PLC (3) .

Beside the ink leak signal, two more signais are sent from the sensing leak pad (9) to be sent to the sensor controller (10).

One signal refers to a loop of 24VDC going back from the sensing leak pad (9) via pin 1 (3 0a) to the sensor controller (10) for connected signal. The other signai reters to the ⁼ mounted signal which is a 0VDC ground signal loop coupled to pin 4 (3 0d) coming from printer holster when the nozzle is mounted.

In sum three signais are sent from the sensing leak pad (26) to the sensor controller (10).

A first signal is the holster mounted signal and will enable the whole function of the ink leak system, a second signal is the connection signal against any intruder or attempt to modify any wiring and a third signal is the ink leak signal which will take place only if the first signal of holster mounted is available.

If the leak is detected, it will send the leak détection to --------the—PLC and—the—printer—along with the—conveyor—will—HSTOP'— for vérification and possibly cleaning. Any incorrect combinations of the three signais above based on the PLC & developed JAVA program, will be detected as 'ABNORMAL' and 30 therefore lead to a stop of the conveyor and shut down the printing system for security vérification.

The Mounted Signal will be sent to make sure that leak pad hasn't been dislocated from the holster and has been mounted properly which is the OVdc ground signal which will activate the circuit inside the sensor box.

The Connected signal gives in indication that no intrusion in the system or attempt to modify any wiring has taken place, which is the looping 24VDC.

An Ink Leak Signal will be available only if the mounted signal of the holster is available which is the open loop awaiting for leak current.

Further to that the PLC signal input, which will be processed by JAVA program, will wait for the Connected Signal and

Mounted Signal in the first place before starting the printer, if any of this signal went missing, it will cause the

JAVA program to send Security Breach status and will immediately shut down the printer and lock the Secure Printer

Cabinet for security vérification.

Figure 6 is an exemplary schematic design of an electrical circuit used in the sensor controller (10). The control 20 circuit according to this preferred embodiment includes a BJT

NPN transistor Q1 with a base receiving the current signais through a resistor, RI. The collector of Q1 will switch the OVDC from common ground connection Emitter to activate the Relay coil RLY1, the Single Pôle Double Touch pin in the RLY1 25 will contact Common pin which carries 24VDC to Normally Open pin to allow the signal to pass thru the Cl connecter pin number 3 as a signal to PLC as Leak Detect and at the same time emits the Red LED1 via current limiter resistor R3 for indication. This process in the circuit will only take place 30 after the PNP BJT transistor Q2 activâtes the RLY2 when there is OVDC ground signal was received by the Base on Q2 once the Leak Pad is mounted inside the print head holster and connected with signal wires and pint head is inserted for the ground signal to connect each other. When the ground signal connects, it is the time where the transistor Q2 receive the

OVDC signal and activate the Relay RLY2 which the 24VDC that was connected to Normally Open pin will contact with the

Common pin to activate the sensing transistor Q1 and at the same time will send the 24VDC signal to pin 4 of connecter Cl and also indicate the function of Mount Detected by LED2 and the same source of 24VDC goes to Connector C2 pin number 2 to be looped as activated source signal in return from C3 pin number 1 and ready to detect the ink leak at the pad as signal 10 number 3 from connector C2 and C3. The return 24VDC as loop from Ink Leak Pad Connector C3 and C2 will be send as Connection Detect signal to pin number 5 of connector Cl for PLC and at the same time will activate the LED3 as Connection Detect indicator. In this circuit the power up signal is 15 ground signal known as Mount Detect from Q2 to activate the 24VDC to go ail over the other sections which will secondly activate the Connection Detect loop for indication of the presence of voltage signal to be ready to activate the Ink Leak détection on the Ink Leak Pad.

The sensor controller (10) also includes a BUT PNP Transistor Q2 which processes the OVDC loop to activate the Mounted Signal and amplify the whole module. The connected loop is connected to the PLC with a current limiting resistor and LED for indication purpose on the sensor controller (10).

......

FIG 7 & exhibits the signais sent to the sensor controller (10) from the sensing leak pad (9) and from the sensor controller (10) to the PLC (3) which processes the signais before sending to the printer controller. Upon receiving Ink 30 Leak Signal the PLC (3) will send the stop printing signal to the printer controller, and the action will follow to retract the print head nozzle as a shutdown initiation process which at the same time will send a log to a HMI control system which stops the productions.

The manufacturer's conveyor will be stop and an alarm signal will be activated for vérification and possibly for cleaning.

A Software Enhanced Printer Security system might perform the 5 following functions upon receiving the signais from the sensor controller as these 2 conditions :

1)During Normal Production:

a) Connected Signal On

b) Mounted Signal: On

c) Leak Signal : Off

2) During Normal Production (Leak Détection):

a) Connected Signal : On

b) Mounted Signal : On

c) Leak Signal : On

Any other combinations of signais or presence of any signal, as a security précaution combination matrix the system will detect as 'ABNORMAL' . This will send an Abnormal or 20 Security Breached alarm which needs authorized person to visit the printer and verify the system (e.g. with OTP password) before enabling the production back to normal.

Reference numérals

5	1 2 3 4 5 6 7	inkjet printing system printer PLC Security cabinet Umbilical cord Printhead holster Product
10	8	Convevor
	9	Leak détection pad
	10	Sensor controller
	11	Signal cable
	12	Notification device
15	13	Output cable
	14	Transducer
	15	Charge electrode
	16	Deflection plate
	17	Driver
20	18	Charge driver
	19	Opening
	20	Ink
	21	Object
	22	Direction of motion of object
25	23	Gutter
	24	Collecter
	25	Pump
	26	Head holder
	27	Slot
30	28	Substrate
	29	Tracks
	30	Pins

Claims (3)

1. CIAIMS

   1. A system for detecting ink leakage in a print head for ?

   continuous inkjet printing, comprising an inkjet print

   5 head device, a sensor controller and a main controller for monitoring the signais from the sensor, the inkjet print head device comprising a transducer, a charge electrode, a deflection plate, a gutter, and a holster, provided that the holster is receiving at least the aforementioned

   10 components of the inkjet print head device, ' wherein the holster comprises an opening for a dedicated outlet for the ink in a printing mode and further comprises an ink leakage détection area, the ink leakage détection area comprising a non-conductive substrate and 15 conductive circuit provided thereon, wherein the sensor controller is operatively connected to the ink leakage détection area, wherein the ink leakage détection area is configured to send to the sensor controller an ink leak signal, a

   20 holster mounted signal and a signal referring about a wiring connection.
2. 2. A system according to claim 1, wherein the ink leakage détection area is at least provided inside the holster and *25--------in a¹ zone neighboring the outlet of the-holstor.-----------
3. 3. A system. according to any of the preceding daims, wherein the ink leakage détection area is a pad.

   30 4. A system according to claim 3, wherein the pad covers at least a part of a holster component.

   19099 5. A system according to any of the preceding daims, wherein the inkjet print head device further comprises a print head holder. 5 6. A system according to any of the preceding daims, further comprising a sensor for detecting unauthorized manipulation of the holster. 1Λ π . a signal, if the holster is connected. 8. Method for detecting ink leakage providing 15 an ink leak signal from a leakage détection area of a holster of a print head device, the ink leakage détection area comprising a non-conductive substrate and conductive circuit provided thereon; a holster mounted signal; a signal referring about a wiring connection; 20 whereas the three signais are sent from a leakage détection area to a sensor controller and further to a control cabinet. 25 9. Method according to daim 8 whereas an indication is provided by the sensor controller if leakage is detected, holster is not properly closed and/or wiring is not correct, is sensed. 30 10. Method according to daim 9, whereas the indication is an appearance on a screen. 14

   11. Method according to claim 9, whereas the indication of the sensor controller is light, preferabiy LED. 5 12. Method according to any of daims 9 to 11, whereas the printing process is stopped, as soon as an indication is

   provided by the sensor controller to the control cabinet that leakage is detected, holster is not properly closed and/or wirinq is not correct, is sensed.