Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-03-12
2001-08-14
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S041000, C347S012000
Reexamination Certificate
active
06273548
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method and circuit for controlling nozzle heads in inkjet printers, in particular nozzle heads of the piezo construction form.
2. Brief Description of the Background of the Invention Including Prior Art
When nozzles are disposed physically closely spaced next to each other in nozzle rows of for example 128 nozzles, it is not possible to shoot simultaneously nozzles disposed neighboring each other. This disadvantage of high nozzle numbers is balanced by an inclined arrangement of the nozzle head or, respectively, of the nozzle row. Such an arrangement of the nozzle rows therefore requires a delayed shooting off of individual nozzles relative to the slider motion and the incorporation angle of the nozzle row. Such a delay circuit is known from the German printed patent document DE-42 26 236 C1. The known unit serves for generating the print cycle and represents a simple method for the delay of the point or dot shooting off with a timer. The known method however cannot be employed in this case, since the distance by which for example the lowest nozzle of the nozzle row has to be delayed corresponds to the complete head width and thus speed variations of the nozzle head would lead immediately to clearly visible print picture distortions.
U.S. Pat. No. 5,563,955 shows a digital signal processor.
SUMMARY OF THE INVENTION
3. Purpose of the Invention
It is a an object of the present invention to achieve a sufficiently point-precise printing of individual nozzles in a nozzle row or, respectively, nozzle rows, disposed at an angle relative to a horizontal line or, respectively, to a print line, and in case of a high nozzle number.
These and other objects and advantages of the present invention will be come evident from the description which follows.
BRIEF DESCRIPTION OF THE INVENTION
According to the present invention there is provided for a circuit for controlling nozzle heads in inkjet printers. A first plurality of nozzles is disposed in a row forming an angle relative to a horizontal and to a line direction, respectively. The nozzles of the first plurality of nozzles exhibit a defined distance from each other and the nozzles of the first plurality of nozzles are to be shot off without a time delay. A second plurality of nozzles is disposed in the row forming the angle relative to the horizontal and to the line direction, respectively, and is electronically distinguished from the first plurality of nozzles. The nozzles of the second plurality of nozzles exhibit a defined distance from each other. The nozzles of the second group of nozzles are disposed interleaved relative to the first plurality of nozzles and the nozzles of the second plurality of nozzles are to be shot off with a time delay of a fraction of a pixel distance. A third plurality of nozzles is disposed in the row forming the angle relative to the horizontal and to the line direction, respectively, and is electronically distinguished from the first plurality of nozzles and from the second plurality of nozzles. The nozzles of the third plurality of nozzles exhibit a defined distance from each other. The nozzles of the third group of nozzles are disposed interleaved relative to the first plurality of nozzles and relative to the second plurality of nozzles. The nozzles of the third plurality of nozzles are to be shot off with a time delay of a multiple of said fraction of the pixel distance. A digital signal processor is connected to the first plurality of nozzles, to the second plurality of nozzles, and to the third plurality of nozzles for controlling the first plurality of nozzles, the second plurality of nozzles, and the third plurality of nozzles. A data processing unit is connected to the digital signal processor for switching the digital signal processor. A unit for generating a print cycle is connected to the data processing unit for delivering print data to the data processing unit. The data processing unit processes the print data as an image of a print line.
Nozzle heads of the first plurality of nozzles, of the second plurality of nozzles, and of the third plurality of nozzles can be of piezo construction. The nozzles of the first plurality of nozzles, of the second plurality of nozzles, and of the third plurality of nozzles can be physically closely spaced. The first plurality of nozzles, the second plurality of nozzles, and the third plurality of nozzles can be disposed on nozzle heads with each having 128 nozzles and furnishing a point grid of 360 dpi.
Preferably, the data processing unit includes a microprocessor, a program storage connected to the microprocessor, a data storage connected to the microprocessor, interfaces connected to the microprocessor for receiving data, a character generator connected to the microprocessor, a memory connected to the microprocessor, and two direct memory access DMA channels connected to the memory and furnished with a direct memory access.
The nozzles of the second plurality of nozzles can be shot off with a time delay corresponding to ⅓ of a distance between two pixels. The nozzles of the third plurality of nozzles can be shot off with a time delay corresponding to ⅔ of a distance between two pixels.
The digital signal processor can be constructed to allow firing successively different sequences of the first plurality of nozzles, of the second plurality of nozzles, and of the third plurality of nozzles.
The pixels can be time delayed relative to an inclination position of the nozzle row for printing a vertical line.
Preferably, a nonlinear time delay relative to a nozzle position is to be applied for shooting off individual nozzles in an incorporation position of 360 dpi.
A tangent of the angle (alpha) relative to the horizontal and to the line direction, respectively, can be defined by the following formula:
tang(alpha)=
n
/((
a·n
)−
x
),
wherein
n is equal to a natural number at least 1,
x is equal to a natural number between 1 and n−1,
a is equal to a second natural number.
The tangent of the angle (alpha) can be defined by parameters as follows:
n is less than 10,
x is equal to 1 or n−1,
a is not larger than n.
The tangent of the angle (alpha) can be defined by parameters as follows:
n is equal to 3,
x is equal to 1,
a is equal to 2.
The digital signal processor can be a digital signal microprocessor.
The digital signal processor can be a general purpose microprocessor working faster than a common digital signal microprocessor.
The object of the present invention is achieved according to the method steps of the present invention for a method for controlling nozzle heads in inkjet printers, in particular nozzle heads of the piezo construction, with physically closely spaced nozzles. The nozzles are disposed in an inclined nozzle row. The inclined nozzle row is electronically subdivided into groups A, B, C. Nozzles belonging to one group A or B or C jump in each case over the nozzles of another group A or B or C, such that the nozzles exhibit a physical distance within an electronically controllable group A, B, C. The nozzles of a first group A are shot off without a time delay. The nozzles of a second group B are shot off with a time delay corresponding to a fraction of a the distance between two pixels. The nozzles of a third group C are shot off with a time delay corresponding to a multiple of this fraction of the distance between two pixels. The grid points are time delayed relative to the inclination position of the nozzle head or, respectively, of the nozzle rows for printing a vertical line. A nonlinear delay is applied for shooting off individual nozzles with an incorporation position of 360 dpi.
Based on this construction, for example only every third nozzle can be shot off simultaneously. Different shooting sequences can be adjusted and set through an electronic nozzle-head control circuit. An overall very precise print picture is therefore generated.
According to the embodiment of this method, it is disclosed that the nozzles to be shot off
Gruner Manfred
Löw Berthold
Kasper Horst M.
Le N.
Nguyen Lamson D.
Tally Computerdrucker GmbH
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