Lars
Einar
Lars
Einar
| 1. | Fluid spraying head (1), preferably for an ink jet printer adapted for ink jet printing of characters or information patterns of variable height onto an object movable relative to said head (1 ), said head (1) including a plurality of drop generating elements and a plurality of nozzles (4a 4g), characterized in that said head (1 ) comprises a plurality of flexible ducts (3a 3g) connected at one end thereof to said drop generating elements of said head (1 ) and connected at the other end thereof to said nozzles (4a 4g); that said nozzles (4a 4g) are displaceably arranged in first slot means (6) of a first guiding member (5) adapted for guiding said nozzles (4a 4g) in a first direction essentially perpendicular to the direction of relative movement of the object with respect to said head (1 ); that each nozzle (4a 4g) is further displaceably arranged in a respective slot (8a 8g) of a group of second slots (8a 8g) of a second guiding member (7); that said second guiding member (7) is movable in a direction essentially perpendicular to said first direction; and that the respective directions of extension of said second slots (8a 8g) are angularly offset with respect to each other. |
| 2. | Fluid spraying head as claimed in claim 1 , characterized in that first and second guiding members (5,7) have the form of first and second nozzle plates (5,7) ; that said first nozzle plate (5) is a fixed plate; and that said second nozzle plate (7) is movable in the direction of relative movement of the object with respect to said head (1 ). |
| 3. | Fluid spraying head as claimed in claims 1 or 2, characterized in I that said first slot means have the form of a single slot (6) for commonly guiding all nozzles (4a 4g) in the first direction. |
| 4. | Fluid spraying head as claimed in one of the claims 1 to 3, characterized. |
| 5. | in that it comprises a plurality of fluid channels (2a 2g) , the end portions (2a 2g) thereof being arranged in a straight line at a fixed distance from each other, said fluid channels (2a 2g) extending to said drop generating elements, and 0 that said flexible ducts (3a 3g) are connected at one end thereof to said end portions (2a 2g). |
| 6. | 5 Fluid spraying head as claimed in one of the claims 1 to 4, 5 characterized by an adjustment screw (9) engaging said first and second guiding members (5,7) for adjusting the relative position of these guiding members (5,7) to thereby adjust the height of the characters or of information pattern to Q be printed. 35. |
The present invention relates to a fluid spraying head in accordance with the prior art portion of claim 1.
Ink jet printing devices having a fluid spraying head are usually used for applying information pattern, characters, letters or figures on objects to be marked, like packages, which are advanced with respect to the spraying head during the ink jet printing operation. Ink jet printing devices have a plurality of ink jet nozzles arranged at the fluid spraying head and a plurality of drop generating elements connected to said nozzles, which drop generating elements might have the form of electromagnetically operated valves for connecting and disconnecting the respective nozzles to a supply of pressurized ink. The respective drop generating elements or valves are controlled by a pattern generator adapted for selecting a number of valves for forming a row-l ike drop pattern extending transversely of the di rection of the relative movement of the object with respect to the fluid spraying head, by repeatedly spraying row-like dot patterns on the object during its movement with respect to the fluid spraying head, which rows of dots or spots together form desired information patterns.
It is desi rable to use a single fluid spraying head for printing patterns or characters of different sizes, i .e. of different heights.
Numerous solutions for obtaining the adjustability of the height of information pattern printed by fluid spraying heads are already known in the art. For example, a prior art fluid spraying head adapted for ink jet printing of characters with variable height is known from US-A-4 215 350.
At the prior art ink jet printing device, the height of the information pattern or of the characters to be printed can be varied by means of switches for selecting a desired group of valves to be actuated, wherein one group of nozzles is composed of every second nozzle of the other group of nozzles.
Another ink jet printing device adapted for printing information pattern of variable height is known from EP-A-0 088 630. The size of the characters to be printed can be varied by activating different selected nozzles within the printing head. Thus, this prior art device essentially corresponds to that known from US-A-4 215 350.
A further ink jet printing device adapted for generating characters of variable height is known from DE-A-0 032 616. The prior art ink jet printer kno.wn from this reference has a rotatable fluid spraying head. When rotating the fluid spraying head for inclining the row of nozzles installed in the spraying head with respect to the usual direction perpendicular to the direction of the movement of the object to be printed, the height of the pattern is reduced. Although the turning or rotating of the fluid spraying head is a simple measure for reducing the height of the respective dot column, it necessitates a relatively complicated sequential control of the respective valves depending on the angular offset of the nozzle row with respect to the vertical direction.
In view of this state of art, the present invention is based on the object of how to achieve a fluid spraying head of the above mentioned kind which is adapted for generating information pattern or characters of variable height and which can be controlled by a relatively simple control unit or pattern generator.
This object is achieved by a fluid spraying head in accordance with the prior art portion of claim 1 having the features indicated in the characterizing portion thereof.
- At the fluid spraying head in accordance with the present invention, the height of the characters or information pattern can be changed without requi ring any changes in the control by means of the pattern generator or control unit connected to the drop generating elements or solenoid ° valves. As an essential further aspect of the present invention, the fluid spraying head can be implemented by simply adding the group of flexible ducts and the two guiding members to a prior art fluid spraying head having a fixed distance between the respective fluid channels located in the head. Hence, a prior art fluid spraying head only capable of ° printing information pattern of a predetermined size can be changed and adapted for printing information pattern of variable height.
At*. antageous - details qf the fluid spraying head in accordance with the present invention are def ined in the sub-claims. 5
Hereinafter, a preferred embodiment in accordance with the present invention will be described with reference to the attached single drawing , which shows a perspective view of an embodiment of a fluid spraying head in accordance with the present invention. 0
A fluid spraying head 1 , which is preferably used in an ink jet printing device includes a plural ity of drop generating elements (not shown in the drawing) which are usual ly formed by electromagnetic valves connected to a container for pressurized ink. These drop generating elements are 5 connected to fluid channels 2a - 2g having fluid channel end portions
2ό - 2ø or outlet openings which are arranged in a straight vertical line at a fixed distance from each other. This f ixed distance, the so-cal led pitch distance, is usual ly approximately 4mm-fB f lexible ducts 3a - 3g are connected to the respective end portions 2a - 2g of said fluid channels 0
2a - 2g.1he.flexible ducts preferably consist of plastic material and have a length of about 20mm. The flexible ducts 3a - 3g are connected to ink jet nozzles or fluid spraying nozzles 4a - 4g which nozzles preferably consist of stainless steel. Each nozzle 4a - 4g has a guiding portion or slide portion 4a - 4g . 5
The fluid spraying head 1 further comprises a first guiding member in the form of a . i rst, fixed nozzle plate 5 having two paral lel , spaced
apart walls 5a , 5b . Each wall 5a - 5b of the first, fixed nozzle plate 5 has a first slot 6 in a direction essentially perpendicular to the direction of movement of the object, onto which a pattern is to be printed with respect to the fluid spraying head 1. The sliding portion 4a - 4g is adapted to slide within this first slot 6 . A second guiding member in the form of a movable nozzle plate - 7 arranged between the walls of the first fixed nozzle plate 5. can be moved in a second direction essentially perpendicular to a first direction defined by the extension of the first slot 6 . The second movable nozzle plate 7 has a number of second slots 8a - 8g which are angularly offset with respect to each other. A respective one of the guiding or sliding portions 4a - 4g. of the nozzles 4a - -Vg. is displaceably arranged in a respective one of the second slots 8a - 8g, of the second movable nozzle plate 7 .
The position of the movable second nozzle plate 7 " between the walls
5a of the fixed first nozzle plate 5 can be adjusted by turning an adjustment screw 9 engaging with both nozzle plates. The adjustment screw 9 can be a manually controlled screw in the simp}' case. In a more sophisticated version of the embodiment the adjustment screw 9 can be electrically actuated by means of a drive motor, which is controlled by means of the control unit or pattern generator of the ink jet printing device. Hence, the height of information pattern can be adjusted by controlling the position of the nozzle plate 7 in the course of the printing process.
When moving the second nozzle plate with respect to the first one, the nozzles 4a - 4g are displaced in the vertical direction due to the co-action of the second slots with the first vertical slot.
The above described embodiment is adapted to be able to easily change the height of the printing pattern on the object to be marked through adjusting the position of the movable plate 7 with respect to the fixed nozzle plate 5 .
Althou gh the preferred embodiments are equipped with a single slot for guiding all nozzles, the same guiding effect can be achieved by a corresponding
number of parallel slots, each slot being arranged to receive a single nozzle.