DE19916219A1 - Ink-jet printer has ink tank mounted on movable carriage, supplied from stationary tank via pump - Google Patents

Abstract

The printer includes at least one movable carriage carrying a jet head, a stationary ink tank, and a carriage tank which is connected via a pump to supply the jet head. The carriage tank (1) is connected directly to the stationary tank via the pump. Ink level sensors in the carriage tank cause the pump motor to switch on or off, so that ink can be supplied from the stationary tank, as required by the carriage tank. The carriage tank may have a first ink chamber (2) for receiving ink, and a second ink chamber (3) divided partially by a wall (3), with respective sensors at different heights. A separate, sealed reference sensor chamber (5) is provided adjacent thereto.

Description

The invention relates to an ink printer with one, at least one nozzle head tra sled, movable back and forth, with, a fixed ink tank and egg nem sled tank connected via a pump that feeds the nozzle heads.

The ink supply from an ink tank to the nozzle head or to several nozzles As is well known, sinking on the sled is designed differently.

Ink cartridges carried on the sled are common, but depending on the type Ink supplies form a large mass and therefore require high acceleration forces other. Such forces lead to high wear of the drive parts. Alternatively a smaller amount of ink could be provided, but the printing performance reduced and a short-term replacement of the empty ink cartridge is forced.

Furthermore, it has already been proposed (DE 44 25 693 A1), ink from a pre Rat tank outside of the sled by means of a pump into a buffer storage tank to promote and regulate the ink level there. The buffer reservoir is supplied then a disposable cartridge over a communicating, flexible tube as a unit with nozzles in the cartridge design. Here is next to the stationary (from exchangeable) storage tank also the buffer reservoir required, so that the effort for the ink supply increases considerably. The tin also fluctuates  level in the disposable cartridge due to the movement of the supply hoses relatively strong, which is very disadvantageous.

It is also known from ink printers on the market by means of a stationary storage tanks and a pump ink into an intermediate tank on the Promote sledges. There is a small volume of ink in the intermediate tank a chamber, which has a threshold on one side, over the superfluous Ink can overflow, which should keep the ink level constant. The Overflow ink, however, must be viewed as waste ink. Basically it has to Always use more ink than is used for writing. All in all considered, this results in high ink consumption with all disadvantages.

The invention has for its object, while avoiding a Puffervorratsbe with low ink consumption in relation to the writing performance of the nozzle head to provide the required amount of ink (with a surcharge) len.

The object is achieved in that the sled tank connected directly to the fixed ink tank via the pump and that the pump motor is switched on by means of ink level sensors located in the sled tank or can be switched off, so that ink is requested by the sled tank from the stationary ink tank in the sled tank is eligible for funding. It will only now ink is still pumped into the sled tank like the consumption of Ink for writing "on site" is done. The amount can be in relation to the typ need to be kept low, so that the problem of high acceleration forces or the wear dependent thereon no longer exists. Waste ink is created not or only to a small extent. A buffer storage container is no longer required.

The measurement using sensors is also redesigned in that the Sled tank an ink chamber (A) for the ink absorption measurement, a commu nizing ink chamber (B) for a replacement measurement and an ink chamber (C) for  Has reference measuring means. This division allows the use of special ones Sensors with desired effects.

A preferred embodiment is that the sled tank is a first Ink chamber for ink absorption and one with a partially closing one Bulkhead separate second ink chamber, each with a different one Height arranged sensor forms and that a sealed separate reference sen sor chamber is located nearby. The bulkhead soothes the ink level and because of the slim design of the chamber there are no waves the bulkhead with its surface perpendicular to the direction of movement of the Schlit tens stands.

In a development of the invention it is provided that the sensors and the reference sensor each consist of a (ink level) thermistor. Such Thermisto ren are semiconductors with temperature-dependent internal resistance. Depending on whether the Thermistors surrounded by air or water find a weaker or stronger one kere cooling instead. Since the internal resistance is strongly temperature-dependent, from whose current value is based on the ink level.

Another advantage follows from the above features in that the ink ni veau thermistor is connected in the first ink chamber as an emergency stop thermistor. In the event that the thermistor working in the second ink chamber If the thermistor is defective, the pump switches off and the Ink printer continues to work undisturbed.

According to another embodiment, it is provided that the bulkhead, which is the first Separates the ink chamber from the second ink chamber to the cover of the sled tank directed towards the housing forms a bulkhead air gap. This allows an air pressure equalization take place between the first and the second ink chamber.

The undesirable wave formation of the ink level is thereby at least steamed, if not completely prevented, by a narrow bulkhead slot, the egg  ne damping liquid connection between the first ink chamber and the two forms and runs in the direction of movement of the carriage hen is. This allows a dampened level compensation of the ink quantities in the and take place in the second ink chamber.

A practical design for mounting the sensors is also ge create the (ink level) thermistors from the lid, one in the lid and Sled tank housing articulated sled tanks, hanging approximately in a rod shape or standing in the ink chambers or in the reference sensor chamber are not.

The electrical connection to the control electronics will be further noted paint prepared in that the (ink level) thermistors by means of connection wires that run through cannulas are connected in the lid by means of solder joints are.

The further connection to the control electronics is advantageous in this regard trained that the connecting wires for the (ink level) thermistors in Bohrun end against a foil circuit board and are soldered. This can be done by a Ribbon connector for connection to the control circuit board of the printer control.

A further embodiment provides that Tin supply openings and the opening of the ink extraction hole are provided are, with at least the sampling tube as a cone connection directly on Dec kel is injected.

It is also proposed that the sled tank housing and the lid be detachable can be locked together.  

Another measure concerns ink cleaning if the ink is e.g. B. by long early inactivity of the printer has changed in its composition should practice. For this purpose, it is provided that a filter tube section on a sampling tube is arranged in the region of a trough-bottom annular bead.

A measure to prevent overpressure or pressure is also advantageous Vacuum in the sled tank, for which it is proposed that a tank on the lid Ventilation opening with a hose connection and an inward Pipe stub is provided.

Another benefit is the purity of the ink. Deposits on the Thermistors can be prevented in that the rods in the area of The contact point of the connecting wires each have a conical shape.

The field of application of the ink printer can also be extended to color ink printers for one multicolor ink printer per ink color each with two ink level thermistors and only a single reference Thermistor for all ink level thermistors in all ink chambers are provided. According to other features, it is contemplated that all ink level thermistors and the reference thermistor connected together in a resistance measuring bridge are. This also allows error situations to be recorded.

The resistance measuring bridge can then be constructed in such a way that the ink level Thermistor, the emergency stop thermistor and the reference thermistor in parallel between the bridge voltage and the ground voltage are switched. This structure ver the resistance measuring bridge is correct on one side, so that when the line is interrupted between an evaluation circuit and the thermistors is still a clear one Signal of voltage is received.  

To adjust the circuit it is then also provided that an ink level Thermistor and side-by-side emergency stop thermistor and reference Thermistor in each case a resistor upstream of the supply voltage is.

In the drawing, embodiments of the invention are shown, which follow in the which are explained in more detail.

Show it:

Fig. 1 shows a cross section through a tank carriage perpendicular to the moving direction of the carriage (not shown),

However, as seen Fig. 2 is a cross section through the carriage tank of FIG. 1 in Be movement direction,

Fig. 3 is a plan view of the carriage tank, in perspective view,

Fig. 4 is a plan view of the carriage tank body, in a perspective view, without the cover,

Fig. 5A merohrs a cross section through the carriage tank in the plane of Entnah or the ink supply opening,

FIG. 5B belonging to Fig. 5A plan view,

Fig. 6 shows a partial cross section through the lid region of the carriage tanks in a slightly larger scale

Fig. 7 shows a partial cross section through the bottom region of the sled tank and

Fig. 8 is a block diagram of a control circuit for the thermistors.

The sled tank 1 ( Fig. 1) is moved on a sled in the plane of the illustration. The sled tank 1 consists of a sled tank housing 1 a and a cover 10 . At least one nozzle head is connected to the sled tank 1 and is supplied with ink. An ink supply, consisting of a stationary ink tank in the printer frame and a pump, pumps the ink into the sled tank. For this purpose, the carriage tank 1 is connected via the pump directly to the stationary ink tank and the pump motor is switched on or by means arranged in the slide tank 1 Ink level sensors switched off, so that ink on Anfor alteration of the carriage tank 1 from the stationary ink tank in the carriage tank ge governs is conveyable and is fed to the nozzle head or the nozzle heads.

The carriage tank 1 ( Fig. 6) has an ink chamber (A) for the ink absorption measurement, an ink chamber (B) for an ink replacement measurement and an ink chamber (C) for reference measuring means.

The practical structure of the sled tank 1 is shown in FIG. 1. There, the sled tank 1 is designed with a first ink chamber 2 for ink reception and a second ink chamber 7 separated by a partially closing bulkhead 3 , each with a sensor arranged at a different height, and also a non-pressurized, sealed separate reference sensor chamber 5 closely connected spatially connected.

The bulkhead 3 is arranged with a bulkhead air gap 3 a to the cover 10 . This allows an air pressure equalization between the ink chambers 2 and 7 to take place.

To form the reference sensor chamber 5 , a partition 4 is provided which is sealed off from the cover 10 and contains only one reference thermistor 33 as a sensor. Likewise, the sensors of the ink chambers 2 and 7 consist of Thermisto ren 31 and 32nd In the upper region of the sled tank housing 1 a, a tub flange 6 is formed in order to releasably connect the lid 10 with suitable means.

The sled tank housing 1 a also has a bulkhead slot 8 ( Fig. 2) which extends to the entire height of the bulkhead 4 in order to create a damped level compensation between the ink chambers 2 and 7 . Both the bulkhead wall 4 and the bulkhead slot 8 contribute to a calming of the ink movement, which is caused by the acceleration of the carriage during printing.

In the cover 10 ( Fig. 1), the thermistors 31 , 32 and 33 are designed and attached as rods 11 , 12 and 13 , respectively. The rod 11 ends with its rod head 11 h (see FIG. 6) approximately within a lid ring wall 11 g. Like the rod 11 , the rod 12 is installed in an electrically insulated manner with a seal for the wire feed-through 12 e or a seal for the wire feed-through 12 f. The rod 13 for the reference thermistor 33 has (like the rods 11 and 12 ) a conical shape 13 a to avoid deposits or ink bags there. These could influence the heat conduction of the sensors and thus the measurement result of the thermistors 31 , 32 , 33 . The ink level thermistors 31 , 32 and 33 are connected by means of connecting wires 33 a and 33 b, which run through cannulas 13 b and 13 c, in the cover 10 by means of solder joints 22 a and 22 b. The connecting wires 33 a and 33 b for the ink level thermistors 31 , 32 and 33 end in holes in a foil circuit board and are routed via a ribbon cable 21 to a control circuit board.

For the lid 10 , a cover groove 14 is provided in the sled tank housing 1 a, in which there is an annular seal 51 which is pressed together to seal or screw together the cover 10 with the sled tank housing 1 a. Extraction tubes 15 (cf. FIG. 5A) are injection molded onto the cover 10 , the hose connections 15 a and 15 b form and extend into the interior of the sled tank housing 1 a with suction tubes 15 c and 15 d (cf. FIG. 7), wherein in the Bodenbe range of the sled tank housing 1 a intake manifolds 15 e and 15 f are formed, the function of which is explained in more detail below.

At the top of the sled tank 1 , ink supply openings 16 are also formed from a tube 16 b with ink supply hose connections 16 a, 10 conical counter-openings being provided on the cover.

In the top surface of the lid 10 , a tank ventilation opening 17 is provided which forms a hose connection 17 a on the outside of a pipe stub 17 b. At the distal end of the connecting hose, not shown here, there is a valve which is closed when the ink printer is being transported. The pipe stub 17 b is directed inwards and cut obliquely ( Fig. 2). The shape of the tube stub 17 ensures that ink drops which are thrown at the tank ventilation opening 17 drip off again and form no deposits.

Fig. 3 shows with the lid 10, the sled tank housing 1 a, the connection wires 33 a and 33 b, which are carried on in the ribbon cable 21 , then within the lid ring wall 11 g, the hose connections 15 a and 15 b and the ink supply opening 16 , the tank ventilation opening 17 and a flange hole 18 .

Fig. 4 allows a view of the sled tank housing 1 a with the cover 10 removed, the bulkhead 3 and the bulkhead slot 8 can be seen from above.

Referring to FIGS. 5A and Fig. 5B, the carriage 1 a tank housing and the cover 10 are releasably connected together, such. B. lockable, the ink supply openings 16 and an opening of the removal tube 15 are provided on the top of the Schlit tentanks 1 . At least the extraction pipe 15 is molded as a cone connection directly onto the cover 10 .

In addition to the bulkhead wall 3 in the sled tank housing 1 a, the tube 16 b for the ink supply opening 16 runs and adjacent the removal tube 15 and below the cover ring wall 11 is the seal 51 . On the hose connection 15 a, a cone connector 71 is placed, on the cone bead 71 a, a socket 41 is supported , which is fastened by means of a screw 42 and which limits its position be. A printhead hose 72 connects to the cone connector 71 .

According to FIG. 5B is in addition to the ink supply opening 16 of the hose connector 15b and the visible cone connector 71 and the tank vent opening 17 inner half of the lid ring Walls 11 g.

Fig. 6 shows on an enlarged scale the fusion seal and the manufacture of the wire feedthroughs. The three steps of the manufacturing process are as follows: In the state before welding, a connecting wire 33 a or 33 b is threaded with the associated sensor. In the second step, a welding tool with a heated electrode 91 is placed on the wire feedthrough and since the lid ring wall 11 g and the rod head 11 h are pressed into the annular cavities 12 b and 12 c by the axial stroke of the welding electrode 91 in the melted state . These areas then result in the seals 12 e and 12 f. The welding electrode can now be removed. In the third step, a foil circuit board is placed and the connecting wires 33 a and 33 b are soldered to the foil conductor plate 33 a and 33 b to solder joints 22 a and 22 b.

Fig. 7 shows the bottom area of the sled tank housing 1 a. At the lower end of the extraction pipe 15 , which forms a suction pipe 15 c or 15 d, each with a suction pipe extension 15 e or 15 f, a filter pipe section 81 is inserted, which extends over a trough bottom gap 82 to a trough bottom annular bead 9 he stretches. Through this filter tube section 81 , deposits 83 do not get into the extraction tube 15 and are not transported further, but are deposited there, as shown.

In Fig. 8, a block diagram of a control circuit in the form of an opposing bridge is shown. The resistance bridge consists of the fixed resistors R1 and the strongly temperature-dependent resistors of the thermistors 31 , 32 and 33 , designated Rth and Rthref. Due to the supply voltage Vcc, the resistors Rth and Rthref heat up due to the current. The resistor Rthref is the reference thermistor 33 , which is always in air in the separate, sealed reference sensor chamber 5 and measures the ambient temperature. The resistors denoted by Rth are the ink level thermistors 31 and 32, depending on the ink level 61, in air or in ink. As the ink level 61 rises, the resistance Rth dips into the ink and cools due to the better heat dissipation over the resistance Rthref, and the resistance increases. The bridge voltage is not equal to zero.

In contrast to this usual function of a resistance measuring bridge, an additional resistance Rkorr (= reference thermistor 33 ) is introduced, which detunes the resistance measuring bridge on one side. In the event that the line between an evaluation circuit (including the resistors R1 and Rkorr) and the ink-level thermistors 31 and 32 in the first ink chamber 2 and the second ink chamber 7 is interrupted, there is nevertheless a clear signal U which indicates the "sufficient ink in ink chambers 2 and 7 " condition. In the event of a fault, this circuit can prevent that too much ink is pumped into the ink chambers 2 and 7 and the chambers could overflow.

The mode of operation is therefore as follows:
The ink conveyed by the pump reaches the sled tank 1 through a liquid connection via the ink guide opening 16 and flows through the tube 16 b into the first ink chamber 2 up to an ink level 61 . When the ink-level thermistor 31 is reached , its temperature drops because its heat dissipation in a liquid is higher than in air. The drop in temperature creates a change in resistance that sends a signal to the controller to turn off the pump motor. During printing, ink is drawn off through a nozzle head via the hose connections 15 a, 15 b, as a result of which the ink level 61 drops. As soon as the ink level 61 has dropped below the ink level thermistor 31 , it heats up again, which in turn causes a change in resistance. This triggers the signal for switching on the pump motor.

In the event of a defect in the ink level thermistor 31, it is in the most ink chamber 2 of the further ink level thermistor 32 , which is higher by a distance Δh. If the ink level 61 in the level control loop rises higher than intended, the ink reaches the emergency stop thermistor 32 after a certain pumping time, which acts directly on the pump motor within the circuit and switches it off. The reference thermistor 33 is located in a separate, sealed reference sensor chamber 5 , in the immediate vicinity of the ink supply, so that temperature fluctuations which occur in the ink printer have as little effect on the measurement result, since the ambient temperature of the ink is practically the reference variable for the Temperature determination is included.

Reference list

1

Sled tank

1

a Sled tank housing

2nd

first ink chamber

3rd

Bulkhead

3rd

a Bulkhead air gap

4th

partition wall

5

Reference sensor chamber

6

Tub flange

7

second ink chamber

8th

Bulkhead slot

9

Tub bottom ring bead

10th

cover

11

Rod

11

g Lid ring wall

11

h rod head

12th

Rod

12th

b annular cavity

12th

c annular cavity

12th

e Sealing the wire feedthrough

12th

f Sealing the wire feedthrough

13

Rod for the reference thermistor

13

a cone shape

13

b cannula

13

c cannula

14

Cover groove

15

Sampling tube

15

a hose connection

15

b hose connection

15

c Intake pipe

15

d suction pipe

15

e Intake pipe approach

15

f Intake manifold approach

16

Ink supply opening

16

a Ink supply hose connector

16

b pipe

17th

Tank ventilation opening

17th

a hose connection

17th

b pipe stub

18th

Flange hole

21

Ribbon cable

22

a solder joint

22

b solder joint

31

Ink level thermistor

32

Emergency stop thermistor

33

Reference thermistor

33

a connecting wire

33

b connecting wire

41

Rifle

42

screw

51

poetry

61

Ink level

71

Cone connector

71

a Taper connector bead

72

Printhead hose

81

Filter pipe section

82

Tub floor gap

83

Deposits

91

Welding electrode
(A) Ink uptake measurement
(B) Ink replacement measurement
(C) Ink chamber reference measuring medium

Claims (20)

1. Ink printer with a, at least one nozzle head carrying, movable carriage, with a stationary ink tank and a sled tank connected via a pump, which feeds the nozzle heads, characterized in that the sled tank ( 1 ) via the pump directly to the stationary Tin is connected tentank and that means is arranged in the carriage tank (1) ink level sensors, the pump motor is switched on or switched off, so that ink can be conveyed regulated at the request of the carriage tank (1) from the stationary ink tank in the carriage tank (1). 2. Ink printer according to claim 1, characterized in that the sled tank ( 1 ) has an ink chamber (A) for the ink absorption measurement, a communicating ink chamber (B) for a replacement measurement and an ink chamber (C) for reference measuring means. 3. Ink printer according to one of claims 1 or 2, characterized in that the sled tank ( 1 ) has a first ink chamber ( 2 ) for ink reception and a second ink chamber ( 7 ) separated by a partially closing bulkhead ( 3 ), each with a different one Height arranged sensor forms and that a sealed separate reference sensor chamber ( 5 ) is arranged nearby. 4. Ink printer according to one of claims 1 to 3, characterized in that the sensors and the reference sensor each consist of an (ink level) thermistor ( 31 , 32 , 33 ). 5. Ink printer according to one of claims 1 to 4, characterized in that the ink level thermistor in the first ink chamber ( 2 ) is connected as an emergency stop thermistor ( 32 ). 6. Ink printer according to one of claims 1 to 5, characterized in that the bulkhead ( 3 ), which separates the first ink chamber ( 2 ) from the second tin chamber ( 7 ) to the cover ( 10 ) of the sled tank housing ( 1 a) ge aligns a bulkhead air gap ( 3 a) forms. 7. Ink printer according to one of claims 1 to 6, characterized in that a narrow bulkhead slot ( 8 ) forming a damping fluid connec tion between the first ink chamber ( 2 ) and the second ink chamber ( 7 ) and extends in the direction of movement of the carriage , is provided. 8. Ink printer according to one of claims 1 to 7, characterized in that the ink level thermistors ( 31 , 32 , 33 ) from the cover ( 10 ), one in a cover ( 10 ) and a sled tank housing ( 1 a) articulated slide tent tanks ( 1 ), extend downward like a rod. 9. Ink printer according to one of claims 1 to 7, characterized in that the (ink level) thermistors ( 31 , 32 , 33 ) hanging or standing approximately in the form of a rod in the ink chambers ( 2 ; 7 ) or in the reference sensor chamber ( 5 ) are arranged. 10. Ink printer according to one of claims 1 to 9, characterized in that the (ink level) thermistors ( 31 , 32 , 33 ) by means of connecting wires ( 33 a, 33 b) which run through cannulas ( 13 b, 13 c), in the cover ( 10 ) by means of soldering ( 22 a, 22 b) are connected. 11. Ink printer according to one of claims 1 to 10, characterized in that the connecting wires ( 33 a, 33 b) for the (ink level) thermistors ( 31 , 32 , 33 ) end in holes in a foil circuit board and are soldered. 12. Ink printer according to one of claims 1 to 11, characterized in that on the top of the sled tank ( 1 ) ink supply openings ( 16 ) and the opening of the ink extraction tube ( 15 ) are provided, with at least the ink extraction tube ( 15 ) as a cone connection is injected directly onto the cover ( 10 ). 13. Ink printer according to one of claims 1 to 12, characterized in that the sled tank housing ( 1 a) and the lid ( 10 ) are releasably lockable with each other. 14. Ink printer according to one of claims 1 to 13, characterized in that a filter tube section ( 81 ) is arranged in the region of a trough-bottom annular bead ( 9 ) on an ink extraction tube ( 15 ). 15. Ink printer according to one of claims 1 to 14, characterized in that on the cover ( 10 ) has a tank ventilation opening ( 17 ) with a hose connection ( 17 a) and an inwardly directed pipe stub ( 17 b) is hen. 16. Ink printer according to one of claims 1 to 15, characterized in that the rods ( 12 ; 13 ) in the region of the contact point of the connecting wires ( 33 a, 33 b) each have a conical shape ( 13 a). 17. Ink printer according to one of claims 1 to 16, characterized in that for a multi-color ink printer per ink color, an ink chamber with two ink level thermistors ( 31 , 32 ) and only a single reference thermistor ( 33 ) for all ink level. Thermistors of all ink chambers are provided. 18. Ink printer according to one of claims 1 to 17, characterized in that all ink level thermistors ( 31 , 32 ) and the reference thermistor ( 33 ) are interconnected in a resistance measuring bridge. 19. Ink printer according to claim 18, characterized in that the ink level thermistor ( 31 ), the emergency stop thermistor ( 32 ) and the reference thermistor ( 33 ) are connected in parallel between the bridge voltage (U) and the ground voltage (GND) are. 20. Ink printer according to one of claims 18 or 19, characterized in that an ink level thermistor ( 31 ) and adjacent emergency stop thermistor ( 32 ) and reference thermistor ( 33 ) each with respect to the supply voltage (Vcc) a resistor ( R1) is connected upstream.