Ink buildup sensor arrangement

Patent metadata

Field	Value
Publication number	US-9770906-B2
Application number	US-201515316378-A
Country	US
Kind code	B2
Filing date	Jun 4, 2015
Priority date	Jun 5, 2014
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A continuous ink jet print head ( 10 ), including: an ink droplet generator ( 116 ) configured to emit an ink droplet ( 158 ) along an undeflected droplet flight path ( 30 ); a charge electrode ( 118 ) configured to impart a charge to the ink droplet; deflector plates ( 120 A, 120 B) adjacent the undeflected droplet flight path, downstream from the charge electrode, and configured to deflect the ink droplet to a deflected droplet flight path that lies within a range of deflected flight paths bounded by at least deflected droplet flight path and a most deflected droplet flight path; a gutter ( 122 ) configured to receive an ink droplet traveling along the undeflected droplet flight path; and an ink buildup sensor ( 102 ) configured to detect an accumulation of ink ( 140 ) relative to a droplet flight path disposed within the range of deflected flight paths.

First claim

The invention claimed is:

1. A continuous ink jet print head, comprising:
an ink droplet generator configured to emit ink droplets along a droplet flight path;
a charge electrode configured to impart a charge to at least some of the ink droplets;
at least one deflector plate adjacent the droplet flight path, downstream from the charge electrode, and configured to deflect at least some of the ink droplets to a deflected droplet flight path;
a gutter configured to receive ink droplets not intended for printing; and
an ink buildup sensor configured to detect an accumulation of ink on a print head surface via a change in an amount of light sensed by the ink buildup sensor.

2. The continuous ink jet print head of claim 1 , wherein the ink buildup sensor comprises a light detector and a light emitter, wherein the light emitter and the light detector are configured such that the accumulation of ink reduces an amount of emitted light that is detected by the light detector.

3. The continuous ink jet print head of claim 2 , wherein the ink buildup sensor is configured to detect the accumulation of ink on an internal surface of the print head that is downstream of the deflector plates and external to an interior of the gutter.

4. The continuous ink jet print head of claim 2 , wherein the ink buildup sensor is configured to detect the accumulation of ink on an internal surface of the print head adjacent an inlet of the gutter.

5. The continuous ink jet print head of claim 2 , wherein the gutter is positioned between the light emitter and the light detector such that the accumulation of ink on an external surface of the gutter is effective to reduce the amount of emitted light that is detected by the light detector.

6. The continuous ink jet print head of claim 3 , wherein the ink buildup sensor comprises a housing comprising a light emitting end and a light detecting end, wherein light emitted by the light emitter is emitted from the light emitting end in a direction generally transverse to the undeflected droplet flight path and is gathered by the light detecting end and delivered to the light detector.

7. The continuous ink jet print head of claim 6 , wherein the light emitter emits light into an emitter transparent cover disposed in the light emitting end, wherein the emitter transparent cover reflects the emitted light toward a sensor transparent cover disposed in the light detecting end, and wherein the sensor transparent cover reflects the light emitted from the emitter transparent cover and directs it toward the light detector.

8. A continuous ink jet printing system, comprising the continuous ink jet print head of claim 1 and a controller in signal communication with the ink buildup sensor and configured to generate a signal indicative of the change in the amount of light sensed by the ink buildup sensor.

9. A continuous ink jet print head, comprising:
an ink droplet generator configured to emit an ink droplet along an undeflected droplet flight path;
a charge electrode configured to impart a charge to the ink droplet;
deflector plates adjacent the undeflected droplet flight path and configured to deflect the ink droplet to a deflected droplet flight path that lies within a range of deflected flight paths;
a gutter configured to receive an ink droplet traveling along the undeflected droplet flight path; and
an ink buildup sensor comprising a light detector, the ink buildup sensor configured to infer an accumulation of ink that grows in a direction toward an ink droplet in flight on the deflected droplet flight path by sensing a reduction in light received by the light detector.

10. The continuous ink jet print head of claim 9 , wherein the ink buildup sensor is configured to generate a signal indicative of the reduction of the light received by the light detector.

11. The continuous ink jet print head of claim 10 , wherein the ink buildup sensor is configured to generate an alarm signal when the signal indicative of the reduction of the light indicates a reduction in the light that exceeds a threshold value.

12. A continuous ink jet printing system, comprising the continuous ink jet print head of claim 10 and a controller in signal communication with the ink buildup sensor and configured to generate an alarm when the signal indicative of the reduction of the light indicates a reduction in the light that exceeds a threshold value.

13. The continuous ink jet print head of claim 9 , wherein the light detector comprises an image detector.

14. The continuous ink jet print head of claim 9 , wherein the ink buildup sensor comprises a light emitter disposed on an opposite side of the gutter than the light detector.

15. The continuous ink jet print head of claim 14 , wherein the ink buildup sensor comprises at least one reflecting surface configured to reflect light emitted from the light emitter.

16. A continuous ink jet printing system, comprising:
an ink droplet generator configured to emit an ink droplet along an undeflected droplet flight path;
a gutter comprising a gutter opening aligned with the undeflected droplet flight path;
an ink buildup sensor comprising a light detector disposed in a light detector location, wherein an amount of light at the light detector location varies as ink builds up on the gutter, and wherein the light detector is configured to detect a variation in the amount of light; and
a controller in signal communication with the ink buildup sensor.

17. The print head of claim 16 , wherein the controller is configured to generate an alarm signal when the amount of light detected by the light detector falls below a threshold value.

18. The print head of claim 16 , wherein the controller is configured to determine a rate of growth of the in buildup, wherein the controller is configured to estimate when a size of the buildup will exceed a threshold value, and wherein the controller is configured to convey to an operator when the size of the buildup will exceed the threshold value.

19. The print head of claim 16 , wherein the ink buildup sensor further comprises a light emitter, and wherein the light emitter and the light detector are disposed on opposite sides of the gutter.

20. The print head of claim 19 , wherein the ink buildup sensor comprises at least one reflecting surface configured to reflect light emitted from the light emitter.

21. The print head of claim 16 , wherein the light detector comprises a linear array or an image sensor.

Assignees

• Videojet Technologies Inc
• Videojet Technologies Inc

Inventors

• Smith Robert
• Salhadin Omer

Classifications

• B41J2/085

  Charge means, e.g. electrodes · CPC title

• B41J2002/1853

  ink collectors for continuous Inkjet printers, e.g. gutters, mist suction means · CPC title

• B41J2002/022

  Control methods or devices for continuous ink jet · CPC title

• B41J2/04561

  detecting presence or properties of a drop in flight · CPC title

• B41J2/185

  Ink-collectors; Ink-catchers · CPC title