Printers and methods for detecting print media thickness therein

• US 10,071,575 B2
• Filed: 10/27/2017
• Issued: 09/11/2018
• Est. Priority Date: 01/18/2017
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Datamax-O'Neil Corporation (Honeywell International Inc.)
• Inventors: Lim, Boon Kheng, Harinarayanan, Aravindkumar, Lim, Danny
• Primary Examiner(s): Tran, Huan
• Application Number:
  US15/795,353
• Publication Number:
  US 20180201035A1
• Time in Patent Office: 319 Days
• CPC Class Codes: B41J 11/0035 Handling copy materials differing in thickness B41J11/20 takes precedence
• CPC Class Codes: B41J 11/0095 Detecting means for copy material, e.g. for detecting or sensing presence of copy material or its leading or trailing end
• CPC Class Codes: B41J 13/0009 control of the transport of the copy material
• CPC Class Codes: B41J 15/042 for loading rolled-up continuous copy material into printers, e.g. for replacing a used-up paper roll; Point-of-sale printers with openable casings allowing access to the rolled-up continuous copy material
• CPC Class Codes: B41J 2/325 by selective transfer of ink from ink carrier, e.g. from ink ribbon or sheet
• CPC Class Codes: B41J 25/312 with print pressure adjustment mechanisms, e.g. pressure-on-the paper mechanisms

Abstract

Printer is provided having support base on which print media travels. Printer includes thickness detection module and processor. Thickness detection module includes pinch arm assembly with pinch arm having first and second ends, encoder, and proximate dual channel encoder sensor. First end is biased toward support base. Encoder with number of circumferentially spaced line pairs is disposed at second end. Pinch arm and encoder configured to rotate in response to engagement of pinch arm with at least print media portion. Dual channel encoder sensor configured to detect rotation direction and encoder count and output signal representing encoder count. Encoder count is number of circumferentially spaced line pairs that pass by dual channel encoder sensor as pinch arm and encoder rotate. Processor is communicatively coupled to dual channel encoder sensor and configured to receive signal and calculate print media thickness of portion from encoder count using conversion factor.

Claims

1. A printer comprising:

a thickness detection module comprising;

a pinch arm assembly comprising;

a pinch arm having a first end and a second end;

an encoder disposed at the second end of the pinch arm, the encoder configured to rotate in response to engagement of the pinch arm with at least a portion of the print media;

a dual channel encoder sensor proximate the encoder and configured to detect a rotation direction and an encoder count indicative of rotation movement of the encoder with respect to the dual channel encoder; and

a processor communicatively coupled to the thickness detection module to calculate a print media thickness of the portion of the print media based on the encoder count and adjust a print head pressure based on the calculated print media thickness.

2. The printer according to claim 1, wherein:

the processor calculates the print media thickness from the encoder count using a conversion factor; and

the conversion factor is one of a predetermined value and a value computed using the encoder resolution.

3. The printer according to claim 1, wherein the encoder count comprises a number of circumferentially spaced line pairs on the encoder that pass by the dual channel encoder sensor as the pinch arm and encoder rotates.

4. The printer according to claim 1, wherein the rotation direction changes each time the print media thickness changes, the rotation direction comprising a first rotation direction and a second rotation direction, the pinch arm and encoder rotating in the first rotation direction in response to an increase in the print media thickness and in the opposite second rotation direction in response to a decrease in the print media thickness.

5. The printer according to claim 4, wherein the encoder count increases with rotation in the first rotation direction and the encoder count decreases with rotation in the opposite second rotation direction.

6. The printer according to claim 5, wherein the pinch arm and encoder are configured to rotate in the first rotation direction in response to engagement with at least the portion of the print media comprising a print medium portion overlying a liner portion and in the opposite second rotation direction in response to engagement with at least the portion of the print media comprising a liner only portion, the encoder count from rotation in the first rotation direction comprising a first encoder count and the encoder count from rotation in the second rotation direction comprising a second encoder count that is less than the first encoder count.

7. The printer according to claim 6, wherein the print media thickness of the print medium portion overlying the liner portion is calculated from the first encoder count and the print media thickness of the liner only portion of the print media is calculated from the second encoder count, a thickness of the print medium calculated by subtracting print media thickness calculated from the second encoder count from the print media thickness calculated from the first encoder count.

8. The printer according to claim 1, wherein the first end of the pinch arm comprises a print media engagement end that engages with a top portion of at least the portion of the print media that is clamped between the print media engagement end and a top of a support base and that disengages therefrom when the pinch arm is not engaged with at least the portion of the print media.

9. The printer according to claim 8, wherein the pinch arm extends radially from a media guide, the pinch arm comprising an elongated substantially planar bar movably mounted on the media guide for rotation with respect to the media guide.

10. The printer according to claim 1, wherein the pinch arm assembly comprises a biasing element for biasing the pinch arm toward a support base and into engagement with at least the portion of the print media.

11. The printer according to claim 10, comprising a bracket above the support base for mounting of the biasing element, wherein a media roll disposed on a media supply spindle of the printer is configured to rotate in a predetermined direction to have the print media thereof fed into and passed through a channel defined between the bracket and the support base.

12. The printer according to claim 1, wherein the thickness detection module is located in the printer along a media path prior to a thermal print head utilized to thermally transfer a portion of ink from an ink ribbon in a ribbon roll to the print media with a thermal print head (TPH) pressure that is automatically adjusted for the calculated print media thickness.

13. The printer according to claim 1, comprising a stop sensor communicatively coupled to the processor to indicate the presence of a print media in the printer.

14. A method for detecting the thickness of print media in a printer, the method comprising:

setting an encoder count to zero in response to receiving a no print media sensor signal;

receiving a signal from a dual channel encoder sensor proximate an encoder disposed at an end of a pinch arm, the signal representing a rotation direction and an encoder count as the encoder rotates in the rotation direction and passes by the dual channel encoder sensor;

calculating a print media thickness of the print media based on the encoder count; and

adjusting the print head pressure based on the calculated print media thickness.

15. The method according to claim 14, wherein the encoder count comprises a number of circumferentially spaced line pairs on the encoder that, during a time interval, pass by the dual channel encoder sensor as the pinch arm and encoder rotate in the rotation direction.

16. The method according to claim 14, wherein receiving the signal comprises receiving a first signal representing a first rotation direction and a first encoder count, and in response to receiving the first signal, calculating the print media thickness of a portion of the print media from the first encoder count.

17. The method according to claim 16, wherein receiving the signal comprises receiving a second signal representing an opposite second rotation direction and a second encoder count, as the pinch arm and encoder rotate in the second rotation direction, and in response to receiving the second signal, calculating the print media thickness of a different portion of the print media from the second encoder count.

18. An assembly configured to detect a print media thickness in a printer, the assembly comprising:

a pinch arm having a first end and a second end;

an encoder disposed at the second end of the pinch arm, the encoder configured to rotate in response to engagement of the pinch arm with at least a portion of the print media;

a dual channel encoder sensor proximate the encoder and configured to detect a rotation direction and an encoder count indicative of rotation movement of the encoder in a single rotational direction with respect to the dual channel encoder; and

a biasing element for urging the pinch arm into engagement with at least the portion of the print media.

19. The assembly according to claim 18, wherein the encoder comprises of a number of circumferentially spaced line pairs, the pinch arm and encoder configured to rotate in response to engagement of the pinch arm with at least the portion of the print media.