Media detection apparatus and method

Abstract

An apparatus and method for automatically calibrating a media sensor configured to detect advancing print media in a printing device. In some embodiments, the apparatus selects a first light intensity level and a second light intensity level greater than the first light intensity level. A light source unit, such as a light emitting diode or laser diode is activated to emit light at the second light intensity level. The light passes though print media, for example, a roll of self-adhesive labels, that is advanced along a print path of the printing device. The amount of light transmitted through the print media is measured as the print media advances. If the measured light increases decreases, the light source unit is reactivated to emit light at the first light intensity level. In some embodiments, the apparatus identifies whether print media has changed or an out-of-stock condition exists.

Description

transmission level is expected to transition from high to low is expected a predetermined value to a higher detected value when a gap 114 is reached.

Once label media 113 is in motion, light detector unit 140 detects the light beam 131 passing through label media 113. The output of light detector unit 140 is monitored, preferably in a substantially continuous manner in step 250, to determine whether the level of detected light rises from a low level to a higher level increases from a predetermined value to a higher detected value (as expected per the assumption set forth above), or falls from a lower level to an even lower level decreases from a predetermined value to a lowe detected value (in contravention of the assumption).

If, in step 255, it is determined that the level of detected light rises from a low level to a higher level increases from a predetermined value to a higher detected value, then the assumption was correct. That is, initially, a gap 114 label portion 111 was positioned within light beam 131, blocking some or all of light beam 131 and lowering the level of light detected by light detector unit 140, and subsequently a label 111 gap 114 passed into the beam, occluding some of all of allowing more light from light beam 131 to transmit through the gap 114 and lowering increasing the level of light detected by light detector unit 140. In this case, the current output level L2 of light source unit 130 is maintained, and the process continues with step 265 as discussed below.

If, on the other hand, in step 255 it is determined that the level of detected light decreases from a low level to a lower level predetermined value to a lower detected value, then the assumption was incorrect in that, initially, a gap 114 was positioned within light beam 131 and subsequently a label 111 portion passed into the beam, thus decreasing the level of light detected by light detector unit 140. In this scenario, the position of the label 111 transition (edge) is recorded, step 260 is performed wherein output level of light source unit 130 is changed to L1 (e.g., lowered).

The process continues with step 265 wherein the position of the label 111 transition (edge) is recorded and the commanded operation is performed (e.g., a print command, a feed command, etc.). After the commanded operation is completed, the label media 113 is advanced until the next gap 114 is positioned in the light beam 131 (e.g., positioned at the start of the next label 111). Then, in step 270, a light measurement MPREV is taken at the conclusion of the commanded operation for use during the next commanded operation, as described above.

Advantageously, a printer according to the present disclosure includes the capability to automatically adjust and adapt to a wide variety of media supplies, particularly those of various lengths, of various label stock and arrangements, and of various light transmissivity.

While several embodiments of the disclosure have been described and shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as examples of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. A method of automatically calibrating a media sensor configured to detect advancing print media, the method comprising:

selecting a first light intensity level and a second light intensity level greater than the first light intensity level;

setting a light source unit to emit light at the second light intensity level;

measuring an amount of the emitted light that is transmitted through the print media;

advancing the print media; and;

setting the light source unit to emit light at the first light intensity level in response to a determination that the light transmitted through the print media is increasing decreasing.

2. The method in accordance with claim 1, further comprising recording a position of the print media.

3. The method in accordance with claim 2, wherein recording a position of the print media includes recording a position at which that the light transmitted through the print media increases or decreases.

4. The method in accordance with claim 1, further comprising recording a measured amount of light transmitted through the print media.

5. The method in accordance with claim 1, further comprising:

determining whether a print media status has changed since a previous operation;

determining whether an out-of-stock condition exists in response to determination that print media status has changed; and

signaling a fault condition in response to a determination that an out-of-stock condition exists.

6. The method in accordance with claim 5, wherein determining whether a print media status has changed since a previous operation includes comparing a current measured amount of light transmitted through the print media with a previously measured amount of light transmitted through the print media.

7. The method in accordance with claim 1, wherein determining whether an out-of-stock condition exists includes comparing a measured amount of light transmitted through the print media to a predetermined out-of-stock value.

8. A label printer configured for automatic media calibration, the printer comprising:

a media drive configured to advance label media from a media supply to a print head;

a setting unit in operable communication with the media drive;

a light source unit in operable communication with the setting unit;

a light detector unit in operable communication with the setting unit and configured to detect light emitted from the light source unit and transmitted at least in part through label media;

wherein the setting unit is configured to:

select a first light intensity level and a second light intensity level greater than the first light intensity level;

cause the light source unit to emit light at the second light intensity level;

measure the amount of the emitted light transmitted through the print media into the light detector unit;

cause the media drive to advance the print media; and

set the light source unit to emit light at the first light intensity level in response to a determination that the light transmitted through the print media is decreasing.

9. The label printer in accordance with claim 8, further comprising a print head in operable communication with the setting unit and configured to imprint visible indicia upon a media label.

10. The label printer in accordance with claim 8, wherein the setting unit is further configured to record a position of the print media.

11. The label printer in accordance with claim 10, wherein a position of the print media is recorded by recording a position at which that the light transmitted through the print media increases or decreases.

12. The label printer in accordance with claim 8, wherein the setting unit is further configured to record a measured amount of light transmitted through the print media.

13. The label printer in accordance with claim 8, wherein the setting unit is further configured to:

determine whether a print media status has changed since a previous operation;

determine whether an out-of-stock condition exists in response to determination that the print media status has changed; and

signal a fault condition in response to a determination that an out-of-stock condition exists.

14. The label printer in accordance with claim 13, wherein the determination whether a print media status has changed since a previous operation includes comparing a current measured amount of light transmitted through the print media with a previously measured amount of light transmitted through the print media.

15. The label printer in accordance with claim 8, wherein the determination of whether an out-of-stock condition exists includes comparing a measured amount of light transmitted through the print media to a predetermined out-of-stock value.

16. The label printer in accordance with claim 8, further comprising a communications interface operably coupled to the setting unit and configured to communicate via a protocol selected from the group consisting of a wired communication protocol or a wireless communication protocol.

17. The label printer in accordance with claim 8, wherein the media drive includes a stepper motor.

18. A method of automatically calibrating a media sensor configured to detect advancing print media, the method comprising:

selecting a first light intensity level for a light source unit corresponding to gap or liner portions of a print media, the first light intensity level selected to allow a light detecting unit to detect a first predetermined value of light when transmitted through the gap or liner portions of a print media;

selecting a second light intensity level for the light source unit corresponding to label portions of the print media, the second light intensity level selected to allow the light detecting unit to detect a second predetermined value of light when transmitted through the label portions of the print media, the second light intensity level greater than the first light intensity level;

setting the light source unit to emit light at the second light intensity level, based at least in part on an assumption that initially a label portion of the print media will be located between the light source unit and the light detecting unit;

advancing the print media and detecting a transition in light intensity from one of the first and second predetermined values of light to a detected value of light transmitted through the print media; and

ascertaining that initially a label portion of the print media was located between the light source unit and the light detecting unit if the transition from the predetermined value to the detected value reflects an increase in the light transmitted through the print media, and/or ascertaining that that, rather than a label portion, initially a gap or a liner portion of the print media was located between the light source unit and the light detecting unit if the transition from the first predetermined value corresponding to the second light intensity level to the detected value reflects a decrease in the light transmitted through the print media.

19. The method of claim 18, further comprising:

setting the light source unit to emit light at the first light intensity level if the transition from the first predetermined value to the detected value reflects a decrease in the light transmitted through the print media, the decrease indicating that, rather than a label portion, initially a gap or a liner portion of the print media was located between the light source unit and the light detecting unit.

20. The method of claim 18, further comprising:

recording a position of the print media corresponding to the transition from the first predetermined value to the detected value, the position representing a label edge;

performing a first print command or feed command;

advancing the print media until light detected by the light detecting unit corresponds to the first predetermined value of light transmitted through the gap or liner portions of the print media.

21. The method of claim 20, further comprising recording a measured amount of light detected by the light detecting unit at the conclusion of the first print command or feed command.

22. The method of claim 21, further comprising: ascertaining whether the print media has been changed prior to performing a second print command or feed command, at least in part by comparing a measured amount of light detected by the light detecting unit upon receiving the second print command or feed command to the measured amount of light detected by the light detecting unit at the conclusion of the first print command or feed command.

23. The method of claim 22, further comprising:

upon ascertaining that the print media has been changed, prior to performing the second print command or feed command:

setting the light source unit to emit light at the second light intensity level, based at least in part on an assumption that initially a label portion of the print media will be located between the light source unit and the light detecting unit;

advancing the print media and detecting a transition in light intensity from the second predetermined value corresponding to the second light intensity level to a detected value of light transmitted through the print media; and

ascertaining that initially a label portion of the print media was located between the light source unit and the light detecting unit if the transition from the second predetermined value to the detected value reflects an increase in the light transmitted through the print media, and/or ascertaining that that, rather than a label portion, initially a gap or a liner portion of the print media was located between the light source unit and the light detecting unit if the transition from the first predetermined value to the detected value reflects a decrease in the light transmitted through the print media.

24. A method of automatically calibrating a media sensor configured to detect advancing print media, the method comprising:

selecting a first light intensity level for a light source unit corresponding to gap or liner portions of a print media, the first light intensity level selected to allow a light detecting unit to detect a first predetermined value of light when transmitted through the gap or liner portions of a print media;

selecting a second light intensity level for the light source unit corresponding to label portions of the print media, the second light intensity level selected to allow the light detecting unit to detect a second predetermined value of light when transmitted through the label portions of the print media, the second light intensity level greater than the first light intensity level;

setting the light source unit to emit light at the second light intensity level, based at least in part on an assumption that initially a label portion of the print media will be located between the light source unit and the light detecting unit;

advancing the print media and detecting a transition in light intensity from one of the first and second predetermined values of light to a detected value of light transmitted through the print media; recording a position of the print media corresponding to the transition from the first predetermined value to the detected value, the position representing a label edge;

performing a first print command or feed command;

advancing the print media until light detected by the light detecting unit corresponds to the first predetermined value of light transmitted through the gap or liner portions of the print media; and

ascertaining that initially a label portion of the print media was located between the light source unit and the light detecting unit if the transition from the predetermined value to the detected value reflects an increase in the light transmitted through the print media, and/or ascertaining that that, rather than a label portion, initially a gap or a liner portion of the print media was located between the light source unit and the light detecting unit if the transition from the first predetermined value corresponding to the second light intensity level to the detected value reflects a decrease in the light transmitted through the print media.