Multiple printhead apparatus with temperature control and method

• US 6,641,243 B2
• Filed: 10/15/2001
• Issued: 11/04/2003
• Est. Priority Date: 01/13/1999
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Schloeman, Dennis, Anderson, Daryl E., Beck, Jeffery S.
• Primary Examiner(s): Nguyen, Judy
• Assistant Examiner(s): Huffman, Julian D.
• Application Number:
  US09/978,367
• Publication Number:
  US 20020067384A1
• Time in Patent Office: 750 Days
• Field of Search: 347/14, 347/17, 347/18, 347/42, 347/60, 347/67, 347/88
• US Class Current: 347/17
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/0458 controlling heads based on heating elements forming bubbles
• CPC Class Codes: B41J 2/04581 controlling heads based on piezoelectric elements

Abstract

An apparatus and method for controlling temperature fluctuations between printhead dies in a multiple printhead die printer. By reducing temperature variations, changes in image intensity that are attributable to temperature variations are reduced.

Claims

1. A printing apparatus, comprising:

a first printhead die having a first temperature mechanism that determines a temperature of said first printhead die;

a second printhead die having control logic and a second temperature mechanism that detects a temperature of said second printhead die;

a mechanism that permits propagation of a signal indicative of the temperature of said first printhead die to said second printhead die control logic; and

wherein said control logic compares a temperature of said first printhead die and a temperature of said second printhead die and produces a signal for heating said second printhead die when said second printhead temperature is lower than that of said first printhead temperature;

wherein said first printhead die includes control logic that produces a signal for heating said first printhead die when said first printhead die is lower in temperature than said second printhead die.

2. The apparatus of claim 1, wherein said temperature signal propagation mechanism is capable of propagating a signal indicative of the temperature of said second printhead die to said first printhead die.

3. The apparatus of claim 2, wherein the control logic of each printhead die is configured such that when the printhead die within which the control logic is located has a temperature lower than that indicated by the temperature propagation mechanism, a signal is generated by the subject control logic that increases the self temperature of that printhead die.

4. The apparatus of claim 2, wherein the control logic of each printhead die is configured such that when the printhead die within which the control logic is located has a temperature higher than that indicated by the temperature propagation mechanism, a signal is generated by the subject control logic that increases the temperature signal on said propagation mechanism.

5. The apparatus of claim 1, wherein said propagation mechanism propagates an analog voltage that is indicative of a corresponding temperature.

6. The apparatus of claim 1, wherein said propagation mechanism propagates a digital code that corresponds to a temperature.

7. The apparatus of claim 1, wherein said control logic includes a mechanism that establishes a threshold temperature between said first and second printhead dies before said signal for heating said second printhead die is produced.

8. A method of printing using an array of printheads, comprising the steps of:

expelling ink from a first printhead of the array of printheads and expelling ink from a second printhead of the array of printheads;

measuring a first temperature of said first printhead and a second temperature of said second printhead;

propagating a first temperature signal to said second printhead;

comparing said first temperature to said second temperature with control logic located on the second printhead;

modifying said second temperature using the control logic located on the second printhead when said second temperature is determined by said comparing step to be essentially unequal to said first temperature; and

heating said first printhead die with control logic located on the first printhead and coupled to the control logic of the second printhead when said first printhead die is lower in temperature than said second printhead die.

9. The method of claim 8 wherein said modifying step further comprises the step of heating said second printhead.

10. The method of claim 8 further comprising the step of generating a first temperature signal related to said first temperature and a second temperature signal related to said second temperature.

11. The method of claim 8 wherein said step of measuring a first temperature is subsequent to an expulsion of ink from said first printhead and said second printhead.

12. The method of claim 8 wherein said comparison step further comprises the step of establishing a temperature difference threshold between said first temperature and said second temperature, which difference threshold must be exceeded for said first temperature and said second temperature to be determined to be unequal.

13. A printing apparatus, comprising:

a first printhead die having a first temperature mechanism that determines a temperature of said first printhead die, a first comparison logic device that receives the temperature of the first printhead die and a first heating mechanism;

a second printhead die, separate from said first printhead die, having a second temperature mechanism that determines a temperature of said second printhead die, a second comparison logic device that receives the temperature the second printhead die and a second heating mechanism; and

wherein said comparison logic devices and said first and second printhead dies are configured such that if the sensed temperature of the first printhead die (T1), minus a threshold temperature (Δ

), is greater than the sensed temperature of the second printhead die (T2), then the second heating mechanism is actuated to heat the second printhead die and wherein if (T2−

Δ

)>

T1, then the first heating mechanism is actuated to heat the first printhead die.