Claims
- 1. A method of locating a scanning printer carriage of an inkjet printer relative to a service station positioned at one end of the scanning axis of the printer carriage comprising the steps of:
- activating an optical sensor mounted on the printer carriage;
- moving the printer carriage along in its scanning direction while optically sensing for a reference mark located on the service station and while monitoring the current position of the printer carriage along its scanning axis by an optical encoder;
- locating the reference mark;
- storing the current position of the printer carriage at which the reference mark has been located; and
- calculating from a known distance of the reference mark to servicing components of the service station and from a known distance of the optical sensor to cartridges held within the printer carriage, to determine the relative location of the cartridges to the servicing components.
- 2. A method of locating a scanning printer carriage of an inkjet printer relative to a service station positioned at one end of the scanning axis of the printer carriage comprising the steps of:
- activating an optical sensor mounted on the printer carriage;
- moving the printer carriage along in its scanning direction while optically sensing for a reference mark located on the service station and while monitoring the current position of the printer carriage along its scanning axis by an optical encoder;
- locating the reference mark;
- storing the current position of the printer carriage at which the reference mark has been located; and
- wherein the step of locating the reference mark comprises the further steps of:
- storing within a processor the readings taken by the optical sensor when moved past the reference mark as a function of the position of the printer carriage,
- calculating the differential of the stored readings and storing the differential as a differential function,
- employing the differential function to determine the turning point of the stored readings function, and
- storing the position of the printer carriage at the turning point as the location of the reference mark.
- 3. A method as claimed in claim 2, wherein the differential function is employed in the following manner:
- the stored differential function values are compared with a threshold value to determine the approximate location of a turning point of the stored sensor readings function and the optical sensor readings are discarded for a fixed distance either side of the turning point,
- a standard function curve is fitted to the remaining stored readings and the position of a turning point of the said standard function curve is determined,
- the position of the printer carriage at this turning point is stored as the location of the reference mark.
- 4. A method as claimed in claim 2, wherein the differential function is employed in the following manner:
- two turning points of the differential function are determined and a standard function curve is fitted to the stored sensor readings located between the two said turning points,
- the position of a turning point of the said standard function curve is determined,
- the position of the printer carriage at this turning point is stored as the location of the reference mark.
- 5. A method as claimed in claim 2, wherein the differential function is employed in the following manner:
- two turning points of the differential function are determined the mean value of the location of the two said turning points is calculated,
- the said mean value is stored as the location of the reference mark.
- 6. A method of locating a scanning printer carriage of an inkjet printer relative to a service station positioned at one end of the scanning axis of the printer carriage comprising the steps of
- 1) activating an optical sensor mounted on the printer carriage,
- 2) moving the printer carriage in a scanning direction along the scanning axis while optically sensing for a reference mark located on the service station and while monitoring the current position of the printer carriage along the scanning axis by an optical encoder,
- 3) locating the reference mark,
- 4) performing a capping operation in which the cartridges held within the printer carriage are capped by caps within the service station,
- 5) uncapping the cartridges,
- 6) repeating steps 2) to 5) an additional N number of times which respects to the current position
- 7) storing an average of the N+1 values of the current position of the printer carriage at which the reference mark has been located in step 3).
- 7. A method as claimed in claim 6, wherein prior to each performance of step 4) the following step is carried out:
- 8) calculating from the location of the reference mark found in step 3) the location of the caps within the service station,
- and wherein the result of step 8) is utilised to more accurately perform the capping operation in step 4).
- 8. A method as claimed in claim 6, wherein the average stored in step 7) is the modal average of the N+1 values of the position of the printer carriage.
- 9. A method as claimed in claim 6, wherein in step 7) the position of the printer carriage stored for future use is a modified modal average of the N+1 positions measured which is calculated by weighting each measured position by the number of immediate and once removed neighbouring positions that are measured.
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is related to the following co-pending commonly assigned applications, all of which are incorporated herein by reference: U.S. Ser. No. 08/811,405 filed Mar. 4, 1997 by Brian Canfield et al entitled MANUALLY REPLACEABLE PRINTHEAD SERVICING MODULE FOR EACH DIFFERENT INKJET PRINTHEAD, U.S. Ser. No. 08/810,485 by Rick Becker et al, filed on Mar. 3, 1997 entitled INKJET PRINTING WITH REPLACEABLE SET OF INK-RELATED COMPONENTS (PRINTHEAD/SERVICE MODULE/INK SUPPLY) FOR EACH COLOR OF INK, U.S. Ser. No. 09/032,386 entitled INKJET PRINTHEAD CAPPING METHOD AND APPARATUS filed Feb. 26, 1998, by Jesus Garcia Maza.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
4686540 |
Leslie et al. |
Aug 1987 |
|
4728970 |
Terasawa |
Mar 1988 |
|
4791435 |
Smith et al. |
Dec 1988 |
|
5796414 |
Sievert et al. |
Aug 1998 |
|