Patent EP0720917A2 successfully refreshed from Google Patents.
EP0720917A2
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EP
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Ink jet printing having printing control
Assignee: Xerox Corp
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Filing: 1996-01-03
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Granted: —
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Expires: 2016-01-03
Abstract
Abstract The printing of an image by a thermal ink jet printer (10) is controlled by a central processing unit (12) based on an internal temperature sensed by temperature sensor (16) of the printer adjacent the printhead (14) and the density of the printed image determined by density determiner 20 in the central processing unit. Prior to printing, the temperature of the printhead is estimated, and the density of the image is determined from stored print data in memory (18) in the central processing unit. Based on the temperature and density, either a single-pass 100% coverage print mode or a double-pass checkerboard print mode is selected. Also, based on the temperature and density, the printhead droplet ejection rate is set. Such control provides a printed image with high quality and prevents misfiring of the ink jets when temperatures and density are high.
Inventors
- 👤 Thomas P. Courtney
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:18
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/485; B41J2/505; B41J2/5056; B41J2/005; B41J2/01; B41J2/17; B41J2/195
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
78 words
A method of controlling printing of an image based on stored data of the image by an ink jet printer (10) having a printhead (14), comprising the steps of: sensing an internal temperature of the ink jet printer; determining density of the stored image to be printed; and selecting a printing mode from one of a single pass 100% coverage printing mode and a double pass checkerboard printing mode based on the sensed temperature and the determined density.
Claim 2
Dependent Claim
25 words
The method of claim 1 further comprising the step of setting a printhead droplet ejection rate based on the sensed temperature and the determined density.
Claim 3
Independent Claim
23 words
The method of claims 1 or 2 wherein the temperature of the printhead is estimated from the sensed internal temperature of the printer.
Claim 4
Independent Claim
122 words
The method of any of the preceding claims, further comprising the step of storing the image data as an array of ON and OFF pixels, and wherein the step of determining the density of the stored image to be printed comprises the steps of: defining a window that encompasses a block of pixels in the array, positioning the window around successive blocks of pixels in the entire array, counting a number of ON pixels in each successive block, recording the number of ON pixels for each block, determining a maximum number of ON pixels in a block from the recorded numbers of ON pixels, and determining the image density for the image data based on the determined maximum number of ON pixels.
Claim 5
Independent Claim
44 words
The method of any of the preceding claims, wherein the step of selecting a printing mode comprises selecting the single pass 100% coverage printing mode when the sensed temperature is about 30°C or below and the density is determined to be high or low.
Claim 6
Dependent Claim
25 words
The method of claim 5 further comprising the step of setting a reduced printhead droplet ejection rate when the density is determined to be high.
Claim 7
Independent Claim
45 words
The method of any one of claims 1 to 4 wherein the step of selecting a printing mode comprises selecting the double pass checkerboard printing mode when the sensed temperature is above about 30°C and setting a standard printhead droplet ejection rate of 6.0 kHz.
Claim 8
Dependent Claim
144 words
An ink jet printer (10) having a printhead and means (12) to control printing thereby, comprising: a memory (18) that stores print data corresponding to an image to be printed; a temperature sensor (16) that senses an internal temperature of the printer adjacent the printhead; a density determiner (20) that determines density of the image to be printed from the stored print data; a controller (22) coupled to the memory, the temperature sensor, and the density determiner that automatically selects one of a single pass print mode and a double pass print mode and automatically sets a printhead droplet ejection rate based on the sensed temperature and the determined density; and a printing mechanism (14) including the printhead coupled to the controller that prints the image based on the stored print data in the selected print mode and the set printhead droplet ejection rate.
Claim 9
Dependent Claim
69 words
The printer of claim 8 wherein the memory stores the print data in an array of ON and OFF pixels and the density determiner comprises a filter that filters through successive blocks of print data in the array, a counter that counts ON pixels in each filtered block, and a computing mechanism that determines a maximum number of ON pixels for a block of print data in the array.
Claim 10
Dependent Claim
25 words
The printer of claims 8 or 9 wherein the controller selects a single pass 100% coverage mode when the temperature is about 30°C or below.
Claim 11
Dependent Claim
24 words
The printer of claim 10 wherein the controller sets a reduced ejection rate of 4.5 kHz when the density is determined to be high.
Claim 12
Dependent Claim
32 words
The printer of claims 8 or 9 wherein the controller selects a double pass checkerboard mode when the temperature is above about 30°C and sets a standard ejection rate of 6 kHz.
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