Projection device and method for projecting at least one image onto a projection surface

Patent metadata

Field	Value
Publication number	US-10073335-B2
Application number	US-201515517176-A
Country	US
Kind code	B2
Filing date	Sep 29, 2015
Priority date	Oct 7, 2014
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A projection device for projecting at least one image onto a projection surface is provided. According to the present disclosure, a control device of the projection device is designed, on the basis of an evaluation of at least one measured value of a measuring device of the projection device determined during a drive of a discharge lamp of the projection device with a current waveform to be checked, to check the current waveform in respect of its suitability for minimizing an electrode burn-back of a first electrode and a second electrode, and in the case of a positive check result, to retain the checked current waveform, and in the case of a negative check result, depending on a checked commutation vector characterizing the checked current waveform, to create, by means of a specifiable algorithm, a modified commutation vector that characterizes a modified current waveform.

First claim

The invention claimed is:

1. A projection device for projecting at least one image onto a projection surface, comprising:
at least one discharge lamp operated by alternating current with a first electrode and a second electrode,
a control device for driving the discharge lamp, wherein the control device is designed to drive the discharge lamp in such a way that the at least one image is projected with a specifiable refresh rate onto the projection surface, wherein the control device is designed to provide at least one base current waveform for driving the discharge lamp, wherein the base current waveform exhibits a current commutation scheme that is described by a commutation vector that comprises a binary value for specifiable locations of a possible current commutation which states whether a current commutation takes place at the location concerned, and
a measuring device for determining a measured value correlated to a state variable of the discharge lamp,

wherein
the control device is designed, on the basis of an evaluation of at least one measured value of the measuring device determined during a drive of the discharge lamp with a current waveform to be checked, to check the current waveform in respect of its suitability for minimizing an electrode burn-back of the first electrode and the second electrode, and
in the case of a positive check result, to retain the checked current waveform, and
in the case of a negative check result, depending on a checked commutation vector characterizing the checked current waveform, to create, by means of a specifiable algorithm, a modified commutation vector that characterizes a modified current waveform.

2. The projection device as claimed in claim 1 , further comprising a color wheel with a specifiable number of color segments, through which each position of a possible current commutation is determined, wherein the projection device is implemented as a DLP projector.

3. The projection device as claimed in claim 1 , wherein the projection device is implemented as an LCD projector which is designed to provide the individual color components for projecting at least one image onto a projection surface simultaneously.

4. The projection device as claimed in claim 1 , wherein the control device is designed to perform the evaluation of at least one measured value of the measuring device in the form of a determination of a rate of change within a specifiable test time interval.

5. The projection device as claimed in claim 1 , wherein the control device is designed to perform the evaluation of at least one measured value of the measuring device in the form of a trend analysis of a specified number of measured values over a specifiable time interval.

6. The projection device as claimed in claim 1 , wherein the control device is designed to perform the testing of the current waveform in respect of its suitability for minimization of an electrode burn-back of the first electrode and the second electrode in a dimmed operating state of the discharge lamp, in which the power currently being drawn by the discharge lamp is at most 90% of the rated power of the discharge lamp.

7. The projection device as claimed in claim 1 , wherein the control device is designed to carry out the drive of the discharge lamp during a test phase with a direct current for the detectability of an electrode tip state of whichever of the first electrode or the second electrode is being operated as the anode during the test phase.

8. The projection device as claimed in claim 1 , wherein the measuring device is designed to determine an electrical voltage between the first electrode and the second electrode as the state magnitude of the discharge lamp.

9. The projection device as claimed in claim 8 , wherein the control device is designed to provide the positive test result in respect of the suitability of the current waveform for the minimization of an electrode burn-back of the first electrode and of the second electrode when a voltage change, as a change in the electrical voltage in the course of a specifiable measuring time interval, adopts at least the value of a lower voltage threshold and at most the value of an upper voltage threshold, and to provide the negative test result when the voltage change adopts a value outside a range specified by the lower voltage threshold and by the upper voltage threshold.

10. The projection device as claimed in claim 1 , wherein the control device is designed to set an uneven number of commutations when generating a modified commutation vector.

11. The projection device as claimed in claim 10 , wherein the control device is designed to set a specifiable frequency modulation factor of the modified current waveform when generating the modified commutation vector.

12. The projection device as claimed in claim 10 , wherein the control device is designed to set a mean frequency generated by the commutations within a frequency range defined by a specifiable minimum frequency and/or by a specifiable maximum frequency when generating the modified commutation vector related to individual segments or to the entire sequence of the modified current waveform.

13. The projection device as claimed in claim 10 , wherein the control device is designed to evaluate a configuration vector that is designed to identify specifiable positions of a possible commutation as the positions of an unwanted commutation or as the positions of a preferred, active commutation when generating the modified commutation vector.

14. The projection device as claimed in claim 1 , wherein the control device is designed to determine, on the basis of the checked commutation vector, the modified commutation vector from the checked commutation vector in such a way that an inactive first position of the checked commutation vector which is adjacent to an active second position of the checked commutation vector is set to active in the modified commutation vector, and the active second position of the checked commutation vector is set to inactive in the modified commutation vector.

15. The projection device as claimed in claim 1 , wherein the control device is designed to determine, on the basis of the checked commutation vector, the modified commutation vector from the checked commutation vector in such a way that either an inactive first position of the checked commutation vector which is adjacent to an active second position of the checked commutation vector is set to active in the modified commutation vector, or an active first position of the checked commutation vector which is adjacent to an active second position of the checked commutation vector is set to inactive in the modified commutation vector.

16. The projection device as claimed in claim 1 , wherein the control device is designed to perform the testing of the current waveform in respect of its suitability for minimization of an electrode burn-back of the first electrode and the second electrode in a dimmed operating state of the discharge lamp, in which the power currently being drawn by the discharge lamp is at most 80% of the rated power of the discharge lamp.

17. The projection device as claimed in claim 1 , wherein the control device is designed to perform the testing of the current waveform in respect of its suitability for minimization of an electrode burn-back of the first electrode and the second electrode in a dimmed operating state of the discharge lamp, in which the power currently being drawn by the discharge lamp is at most 90% of the rated power of the discharge lamp.

18. A control device of

Assignees

• Osram Gmbh

Inventors

• Czichy Marc
• Heise Michael
• Baier Markus
• Magg Norbert
• Sixtensson Daniel

Classifications

• G03B21/206 Primary

  Control of light source other than position or intensity · CPC title

• G03B21/2026

  Gas discharge type light sources, e.g. arcs · CPC title

• H05B41/36

  Controlling · CPC title

• H05B41/2928

  for protecting the lamp against abnormal operating conditions · CPC title

• G03B21/005

  Projectors using an electronic spatial light modulator but not peculiar thereto · CPC title