Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-05
2001-01-23
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S059000
Reexamination Certificate
active
06176569
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally directed to ink jet printers. More particularly, the present invention is directed to a three-dimensional ink jet heater addressing scheme.
BACKGROUND OF THE INVENTION
As the printing resolution of ink jet printers increases, so does the number of nozzles on the ink jet print head. For each nozzle used to eject ink to form printed pixels on the print medium, there is a corresponding heating element. As nozzles counts have increased, driver circuitry has been incorporated on the print head substrate along with the heating elements. The driver circuitry activates the heating elements in a time-multiplexed fashion, with combinations of power and address lines being used to select the heating element or elements to be activated. For example, in a 208-nozzle print head, there may be sixteen power lines and 13 address lines for a total of 29 signal lines used to activate
208
heating elements. (16×13=208).
In a typical ink jet printer design having a print head that scans across the print medium, each of the signal lines generally must be brought from a printer controller to the print head through a flexible cable. Also, there must be an interconnection, such as a bonding pad on the print head for each signal line that connects to the driver circuitry on the print head substrate. In a low-cost ink jet printer design, the cost of such interconnects, and the cost of print head drivers, and can be quite significant. A reduction in signal lines would simplify the design and reduce the cost of printers and print heads. Further, reducing the number of signal lines would allow more flexibility in possible design configurations.
Therefore, a heating element addressing scheme is needed that reduces the number of signals lines connecting the print head to the printer controller.
SUMMARY OF THE INVENTION
The foregoing and other needs are met by an apparatus for receiving image data representing an image to be printed on a print medium, and for addressing ink jet heating elements based on the image data to cause ejection of ink droplets from ink jet nozzles toward the print medium. The apparatus includes a controller for generating electrical signals based on the image data. The electrical signals generated by the controller include address signals, power signals, and first and second bank signals. The controller determines an on or off state for each of the electrical signals depending on the image data. The controller alternates the first and second bank signals between on and off states, where the first bank signal is off when the second bank signal is on, and where the second bank signal is off when the first bank signal is on.
The apparatus also includes a first bank line connected to the controller for carrying the first bank signal, and a second bank line connected to the controller for carrying the second bank signal. The apparatus has address lines connected to the controller for carrying the address signals, where m represents the number of address lines. Power lines are connected to the controller for carrying the power signals, where n represents a number of power lines.
The apparatus includes a print head having first and second driver circuits. Each of the first driver circuits is connected to the first bank line and to a corresponding one of the m address lines. The first driver circuits enable flow of a first driving current when the first bank signal and the address signal are simultaneously in an on state on the first bank line and the corresponding address line. Each of the second driver circuits is connected to the second bank line and to a corresponding one of the m address lines. The second driver circuits enable flow of a second driving current when the second bank signal and the address signal are simultaneously in an on state on the second bank line and the corresponding address line. The print head includes m×n number of first driver circuits and m×n number of second driver circuits.
The print head also has first heating elements, each of which is connected to a corresponding one of the first driver circuits and to one of the n power lines. A particular one of the first heating elements is activated by the first driving current when the power signal is in an on state on the connected power line and the corresponding one of the first driver circuits enables flow of the first driving current. The print head includes second heating elements, each of which is connected to a corresponding one of the second driver circuits and to one of the n power lines. A particular one of the second heating elements is activated by the second driving current when the power signal is in an on state on the connected power line and the corresponding one of the second driver circuits enables flow of the second driving current. The print head has m×n number of first heating elements and m×n number of second heating elements.
By introducing the first and second bank signals in a third dimension of heating element addressing, the present invention provides an addressing scheme that significantly reduces the number of power lines as compared to a conventional two-dimensional addressing scheme. A typical two-dimensional addressing scheme requires twice the number of power lines as does the present invention. Since signal lines and their interconnections to the print head represent a significant portion of the cost in a low-cost ink jet printer, the present invention offers significant cost advantages.
In another aspect, the invention provides a method for receiving image data and activating ink jet heating elements based on the image data to cause ejection of ink droplets from ink jet nozzles toward a print medium. The heating elements to which the method applies comprise odd heating elements in a first bank and even heating elements in an second bank. The method includes the step of generating m number of address signals which are periodically in on and off states, and n number of power signals which are in on or off states depending on the image data. Each one of the n power signals is provided to a corresponding one of n number of power groups of heating elements, where each power group includes m number of even heating elements and m number of odd heating elements. A first bank signal and a second bank signal are generated in alternating on and off states, where the first bank signal is in an off state when the second bank signal is in an on state, and the second bank signal is in an off state when the first bank signal is an on state. A first current path is provided for flow of a first driving current when the first bank signal and one of the address signals are simultaneously in an on state. The method includes causing the first driving current to flow through the first current path when the first current path is provided and one of the n number of power signals is in an on state. One of the odd heating elements is activated by the flow of the first driving current. Similarly, a second current path is provided for flow of a second driving current when the second bank signal and one of the address signals are simultaneously in an on state. The method includes causing the second driving current to flow through the second current path when the second current path is provided and one of the n number of power signals is in an on state. One of the even heating elements is activated by the flow of the second driving current.
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p
Anderson Frank Edward
Eade Thomas Jon
Gibson Bruce David
Parish George Keith
Barlow John
Lexmark International Inc.
Luedeka Neely & Graham
Sanderson Michael T.
Stephens Juanita
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