Printing apparatus with adaptive servicing sled control and method

• US 6,641,245 B1
• Filed: 05/23/2002
• Issued: 11/04/2003
• Est. Priority Date: 05/23/2002
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Kelly, Kieran B, Stallbaumer, Philip
• Primary Examiner(s): Meier, Stephen D.
• Assistant Examiner(s): Do, An H.
• Application Number:
  US10/155,457
• Time in Patent Office: 530 Days
• Field of Search: 347/19, 347/23, 347/22, 347/33, 347/34, 347/29
• US Class Current: 347/19
• CPC Class Codes: B41J 2/16547 the wipers and caps or spittoons being on the same movable support

Abstract

An inkjet printer having functionality to adaptively control an amount of force applied to a servicing sled used to clean an inkjet printhead. In selecting a run force to be applied to the servicing sled, a test force is applied to the servicing sled to determine if the servicing sled will move a predetermined distance under the test force.

Claims

1. A method of adaptively controlling an amount of force applied to a servicing sled used to clean an inkjet printhead, comprising:

(a) applying a run force associated with a stored force level to the servicing sled;

(b) sensing a first unintentional stall of the servicing sled during application of the run force;

(c) selecting a lowest test force from a plurality of test forces to be a current test force;

(d) applying the current test force to the servicing sled;

(e) upwardly incrementing the current test force if a second unintentional stall of the servicing sled is sensed during application of the current test force, otherwise storing an adapted force level indication associated with the current test force in place of the stored force level indication; and

(f) repeating operations (d) and (e) if the current test force is less than a highest test force form the plurality of test forces, otherwise storing an adapted force level indication associated with the highest test force in place of the stored force level indication.

2. The method of claim 1, wherein operation (a) includes attempting to move the servicing sled from a home position adjacent a first stop to an intentional stall position adjacent a second stop such that a wiper mounted on the servicing sled engages the printhead and discontinuing the application of the applied force upon sensing that the servicing sled has stopped moving.

3. The method of claim 2, wherein operation (b) includes comparing a distance actually traveled by the servicing sled with a predetermined distance, the first unintentional stall being sensed if the actually traveled distance is less than the predetermined distance.

4. The method of claim 2, wherein operation (a) further includes reducing the amount of force applied to the servicing sled in expectation of the servicing sled arriving at the intentional stall position.

5. The method of claim 1, wherein the run force and the test forces are produced by a drive motor controlled by pulse width modulation.

6. The method of claim 1, wherein each test force corresponds to an associated run force and each test force is smaller than the corresponding run force.

7. The method of claim 1, wherein each test force corresponds to an associated run force and each test force is smaller than the corresponding run force except for a highest test force of the plurality of test forces, the highest test force being the same as the corresponding run force.

8. The method of claim 1, wherein operation (d) includes a first move attempt to move the servicing sled to a home position adjacent a first stop and a second move attempt to move the servicing sled from the home position to an intentional stall position adjacent a second stop such that during the second move attempt a wiper mounted on the servicing sled engages the printhead.

9. The method of claim 8, wherein operation (e) includes comparing a distance actually traveled by the servicing sled during the second move attempt with a predetermined distance, the second unintentional stall being sensed if the actually traveled distance is less than the predetermined distance.

10. The method of claim 8, wherein operation (d) further includes a third move attempt to move the servicing sled from the intentional stall position to the home position such that during the third move attempt the wiper engages the printhead.

11. The method of claim 10, wherein operation (e) includes comparing a distance actually traveled by the servicing sled during the second move attempt with a predetermined distance and comparing a distance actually traveled by the servicing sled during the third move attempt with the predetermined distance, the second unintentional stall being sensed if either actually traveled distance is less than the predetermined distance.

12. An inkjet printer, comprising:

a printhead adapted to progressively deposit ink droplets on a print medium;

a servicing sled having a wiper for removing contaminants from the printhead;

a drive motor coupled to the servicing sled with a sled drive linkage to move the servicing sled with respect to the printhead;

a sensor adapted to generate a signal indicative of distance traveled by the servicing sled; and

a control assembly adapted to control the drive motor so as to vary mechanical force applied to the servicing sled, the control assembly programmed to select a run force from a plurality of run forces with which to move the servicing sled during a printhead service by controlling the drive motor to apply a test force from a plurality of test forces to the servicing sled, each test force corresponding to one of the run forces, and by comparing a distance traveled by the servicing sled during application of the test force and a predetermined distance to determine if the test force is sufficient to actuate the servicing sled.

13. The printer of claim 12, wherein during selection of the run force, the control assembly executes code to:

(a) select a lowest test force from the plurality of test forces to be a current test force;

(b) apply the current test force to the servicing sled; and

(c) upwardly increment the current test force if an unintentional stall of the servicing sled is sensed during application of the current test force, otherwise setting the run force corresponding to the current test force as the selected run force; and

(d) repeat operations (b) and (c) if the current test force is less than a highest test force form the plurality of test forces, otherwise setting the run force corresponding to the highest test force as the selected run force.

14. The printer of claim 12, further comprising a memory for storing the selected run force level.

15. The printer of claim 12, wherein selection of the run force level is made following detection an unintentional stall during the printhead service.

16. The printer of claim 15, wherein during the print head service the control assembly executes code to attempt to move the servicing sled from a home position adjacent a first stop to an intentional stall position adjacent a second stop and to discontinue the application of force upon sensing that the servicing sled has stopped moving.

17. The printer of claim 16, wherein detection of the unintentional stall includes comparing a distance actually traveled by the servicing sled during the move attempt with a predetermined distance, the unintentional stall being sensed if the actually traveled distance is less than the predetermined distance.

18. The printer of claim 16, wherein during the printhead service the control assembly executes code to reduce the amount of mechanical force applied to the servicing sled in expectation of the servicing sled arriving at the intentional stall position.

19. The printer of claim 12, further comprising a drive motor controller for supplying pulse width modulated electrical power to the drive motor in accordance with a control output signal from the control assembly.

20. The printer of claim 12, wherein each test force is smaller than the corresponding run force.

21. The printer of claim 12, wherein each test force is smaller than the corresponding run force except for a highest test force of the plurality of test forces, the highest test force being the same as the corresponding run force.

22. The printer of claim 12, wherein during the actuation of the servicing sled with the test force, the control assembly is programmed to attempt a first move of the servicing sled to move the servicing sled to a home position adjacent a first stop and to attempt a second move of the servicing sled to move the servicing sled from the home position to an intentional stall position adjacent a second stop.

23. The printer of claim 22, wherein the distance actually traveled by the servicing sled during the second move attempt is the distance compared with the predetermined distance, the test force being sufficient if the actually traveled distance is as great as the predetermined distance.

24. The printer of claim 22, during the actuation of the servicing sled with the test force, the control assembly is programmed to attempt a third move of the servicing sled to move the servicing sled from the intentional stall position to the home position.

25. The printer of claim 24, wherein the controller is programmed to compare a distance actually traveled by the servicing sled during the second move attempt with the predetermined distance and to compare a distance actually traveled by the servicing sled during the third move attempt with the predetermined distance, the test force being sufficient if both actually traveled distances are as great as the predetermined distance.