Abstract: A method of the invention is for operating a media feed motor of a printer to perform a media feed move of a predetermined distance and includes steps a) through c). Step a) includes choosing a position-error scale factor for a media feed move that is within a range of distances. Step b) includes calculating a media-feed-motor drive signal which includes a position error contribution substantially equal to the product of the position-error scale factor and the difference between a desired final media position at the end of a media feed move and the actual media position. Step c) includes modifying the position error contribution in step b) to reduce its effect when the predetermined distance is greater than the maximum distance within the range but not when the predetermined distance is less than the maximum distance within the range.

Abstract: An analog encoder system repeatedly switches back and forth between monitoring of first and second encoder output signals to track movement of a structure associated with the encoder. An energization level of an encoder light element may be controlled in accordance with which encoder output signal is being monitored.

Abstract: A multi-function media eject system and method for operation particularly useful for ink jet printers. At the start of a print job, the media type and print format are determined. If the media is either banner paper or envelope, or if the print format is draft quality printing, wings and kickers of the eject system are disabled, so the media exits the printer without support from the wings or influence from the kickers.

Abstract: A method of calculating at least a component of ink drop velocity in an ink jet printer includes jetting at least one first ink drop from a printhead firing plane. It is detected when the first ink drop is a first predetermined distance away from a reference plane. A first time period between the jetting and the detecting of the first ink drop is measured. At least one second ink drop is jetted from the printhead firing plane. It is detected when the second ink drop is a second predetermined distance away from the reference plane. A second time period between the jetting and the detecting of the second ink drop is measured. A difference between the first predetermined distance and the second predetermined distance is divided by a difference between the first time period and the second time period.

Abstract: An encoder including a light source for emitting light, a photodetector for detecting at least part of the light emitted by the light source, and an encoder film including a plurality of alternating bars and windows and being located between the light source and the photodetector. The encoder includes a mask including a plurality of alternating bars and windows, the mask being located between the light source and the photodetector. The encoder further includes a spacer located between the mask and the encoder film, the encoder film contacting the spacer to maintain a predetermined spacing between the mask and the encoder film.

Abstract: A printhead alignment sensor for an ink jet printer includes two terminals defining a substantially linear gap therebetween. An ink support device supports ink in the gap between the terminals. An electrical measuring device detects a change in an electrical resistance between the terminals when ink is supported in the gap by the ink support device.

Abstract: In an inkjet printer, a print medium is selectively printed on in a multiple pass printing mode and/or a single pass printing mode. During the single pass printing mode, the print medium is printed on in a single pass height. The print medium is advanced a distance less than the single pass height. During the multiple pass printing mode, the print medium is printed on in a multiple pass height. The multiple pass height is less than the single pass height. The print medium is advanced a distance approximately equal to the multiple pass height.

Abstract: A printhead firing control system for an inkjet printer includes a printhead mounted for movement across a paper path and an encoder for producing a digital output signal indicative of movement of the printhead. A filter circuit is connected to receive the digital output signal for filtering the digital output signal to remove frequency variations which meet at least one predetermined parameter, thereby providing a filtered digital signal. A fire-pulse generation circuit receives the filtered digital signal from the filter circuit and produces printhead heater resistor drive pulses based at least in part upon the filtered digital signal. This arrangement provides for improved printing accuracy by eliminating frequency changes in the digital encoder signal which may erroneously be caused by mechanical vibrations or other noise within the printer. An improved digitally controlled oscillator construction is also described.

Abstract: An analog encoder system repeatedly switches back and forth between monitoring of first and second encoder output signals to track movement of a structure associated with the encoder. Switching between signals is controlled according to an upper intersection amplitude and a lower intersection amplitude of the two encoder output signals.

Abstract: An optical encoder assembly for an optical encoder for determining rotation of a rotatable shaft. An encoder housing is non-engageable with the shaft. A receiver plate is attached to the encoder housing, has a first side and a substantially opposing second side, and has a through hole and a window both extending from the first side to the second side, wherein the through hole is engageable with the shaft. An encoder mask is attached to the first side of the receiver plate, has a shaft hole engageable with the shaft, and has a mask grating positioned over the window. A light emitter is aligned to face the first side of the receiver plate and is positioned over the mask grating. A light detector is attached to the second side of the receiver plate and is positioned over the window.

Abstract: A method of printing with an ink jet printer includes providing a printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Print data corresponding to first columns of pixel locations is provided. The print data includes for each pixel location in the first columns both a respective large dot print datum and a respective small dot print datum. One of the respective large dot print datum and the respective small dot print datum is printed at a first pixel location of the corresponding pixel locations in the first columns. Second columns of pixel locations interleaved with the first columns of pixel locations are provided.

Abstract: A method of calculating at least a component of ink drop velocity in an ink jet printer includes jetting at least one first ink drop from a printhead firing plane. It is detected when the first ink drop is a first predetermined distance away from a reference plane. A first time period between the jetting and the detecting of the first ink drop is measured. At least one second ink drop is jetted from the printhead firing plane. It is detected when the second ink drop is a second predetermined distance away from the reference plane. A second time period between the jetting and the detecting of the second ink drop is measured. A difference between the first predetermined distance and the second predetermined distance is divided by a difference between the first time period and the second time period.

Abstract: A printhead alignment sensor for an ink jet printer includes at least two terminals defining a gap therebetween. An electrical measuring device detects a change in an electrical parameter between two of the terminals when ink is in the gap between the at least two terminals.

Abstract: A method for reducing visual printing defects produced by an ink jet printer includes the steps of providing a first printhead nozzle array spaced apart from a second printhead nozzle array in a main scan direction; defining a plurality of rasters for scanning during a first unidirectional scan of the first printhead nozzle array and the second printhead nozzle array; and printing on a print medium with both the first printhead nozzle array and the second printhead nozzle array to form printing lines traced along at least a portion of the plurality of rasters during the first unidirectional scan, wherein the first printhead nozzle array is controlled to print in a first shingling pattern and the second printhead nozzle array is controlled to print in a second shingling pattern.

Abstract: A method of analog encoder initialization involves repeatedly adjusting an encoder light element energization level and dc offsets of the encoder channels to produce desired signals.

Abstract: A printer assembly and a method for determining the position of a printer component, such as a printer paper-feed roller, during a move of the printer component from an initial position toward a desired final position. An analog encoder is operatively connected to the printer component, and a threshold device is connected to the analog output of the analog encoder. The position of the printer component is determined from the digital output of the threshold device and a digitization of the analog output of the analog encoder.

Abstract: A method for reducing horizontal banding on media in an ink jet printer involves the step of moving the media repeatedly back and forth along a media movement path during a printing scan of at least one print head, the printing scan defined by movement of the print head across the media movement path as ink is ejected from the print head onto the media.

Abstract: A method for synchronizing the print start position for a printer carriage on an inkjet printer that includes the steps of: (a) providing an encoder signal indicative of a position of an inkjet printer carriage relative to a substrate being printed upon or a printer platen, where the encoder signal is an alternating voltage signal with an encoder signal frequency; (b) filtering and dividing the encoder signal to provide a fire pulse signal, where the fire pulse signal is an alternating voltage signal with a fire pulse signal frequency that is a multiple of the encoder signal frequency; (c) detecting a rising edge of the encoder signal preceeding a predetermined print start position of the printer carriage; (d) upon detection of the rising edge of the encoder signal in step (c), detecting a next falling edge of the fire pulse signal; (e) upon detection of the next falling edge of the fire pulse signal in step (d), detecting a count of the next rising edges of the fire pulse signal; and (f) assigning a synchron

Abstract: A method of analog encoder initialization involves repeatedly adjusting an encoder light element energization level and dc offsets of the encoder channels to produce desired signals.

Abstract: A method for reducing cyclic print errors. Applicants discovered that the cause of certain cyclic print errors was inconsistent (i.e., unequal) line spacing on the linear encoder strip used by the printer to track the position of the print head. Such inconsistent line spacing was caused by the inability of the device which makes/prints linear encoder strips to consistently match the ideal consistent line spacing desired and expected by the printer. Applicants found that such cyclic print errors were eliminated by choosing, obtaining, and installing a linear encoder strip having a consistent line spacing within the resolution capabilities of the device and, in one example, closest to the ideal consistent line spacing.