JP2006293032A - Projection type system by dc lit high-pressure discharge lamp and method for activating projection type system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for synchronizing a color filter capable of minimizing irregularity in image quality and the current of a lamp. <P>SOLUTION: In the method for activating a projection type system where light (ψ1) radiated from the high-pressure discharge lamp (1) lit by a DC current (A) is successively made to pass through color segments (3a) to (3f) obtained by dividing the color filter (3) into plurality, and continuously reflected by an optical device (4) so as to project an image on a screen (7), the color filter (3) has a plurality of filters comprising red, green and blue filters successively, and current intensity in the second half of the green segments (3b) and (3e) is set to a current decrease pulse that it is made lower than the current intensity in the first half of the green segments (3b) and (3e), and timing that the current decrease pulse is generated is synchronized with a synchronizing signal (S) generated at the predetermined position of the green segments (3b) and (3e), and the optical device (4) is synchronized with the synchronizing signal (S). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection type system including a reflection type optical element called DMD (Digital Micromirror Device) and an optical element such as a color filter, and an operation method thereof.

  In this type of projection system, particularly a home theater or an RPTV (rear projection television), a color filter called a color wheel is generally a 6-segment system in which, for example, RGBRGB are arranged on the same circumference. Regarding the gradation of the device, the position of each mirror of the DMD is expressed as ON or OFF, and a gray intermediate color is created depending on how long the ON state continues. For example, 256 gradations are usually produced with a resolution of 8 bits. However, in response to the demand for higher image quality, fine vibration noise (Dither Noise) is generated due to insufficient gradation power when expressing the green component in the dark part.

FIG. 3 shows the waveform of the conventional DC lamp current (A) and the waveform (S) of the synchronizing signal from the color filter (3). Here, an example in which a pulse current is superimposed on R (red) is shown. This method is described in Japanese Patent Application Laid-Open No. 2004-212890 as a reference document. In other words, the pulse current is superimposed on the DC lamp current to stabilize the arc, and at the same time, the pulse current is superimposed on the DC lamp current in synchronization with a predetermined segment, thereby suppressing flicker caused by arc jump and gradation disturbance. It is intended to make the minimization of both compatible.
JP2004-212890

  However, the above-mentioned method cannot adequately meet the demand for higher image quality, and recently it has improved the fine vibration noise that occurs due to insufficient tone power when expressing the green component especially in dark areas. In order to achieve this, the current intensity in the second half of the green segment is reduced to approximately 50% or approximately 25% from the first half, and a method of increasing the number of bits equivalently is applied. It is said that 1 bit can be increased by approximately 50%, and 2 bits can be increased by approximately 25%.

  Although this method is generally recognized, since a current decrease pulse occurs in the middle of the green segment, image quality disturbance caused by its transient characteristics occurs as a side effect, and this further increases the image quality. It has become a big challenge for demand. The first object of the present invention is to realize a method of synchronizing with a color filter capable of minimizing image quality disturbance, and to provide a projection type system capable of maintaining arc stabilization at that time and an operating method thereof. With a purpose.

  “Claim 1” is an operation method of the projection type system according to the present invention, wherein “the color segments (3a) to (3f) obtained by dividing the color filter (3) into a plurality of high voltage lights lit with a direct current (A)” An operation method of a projection type system in which light (φ1) emitted from a discharge lamp (1) is sequentially passed and subsequently reflected on an optical element (4) to project an image on a screen (7), and a color filter ( 3) has a plurality of filters composed of red, green and blue in sequence, the current intensity in the second half of the green segment (3b) (3e) is lower than the current intensity in the first half of the green segment (3b) (3e) The generation timing of the current reduction pulse is synchronized with the synchronization signal (S) generated at a predetermined position of the green segment (3b) (3e) and the optical element (4) is synchronized with the synchronization signal (S). It was made to synchronize. "

  “Claim 2” is the operation method of the projection system according to claim 1, wherein “the blue segment (3c) (3f) and the red segment (3a) (3d) continuing to the green segment (3b) (3e)” The DC current (A) was controlled so that the current intensity was a current increasing pulse that increased from the current intensity of the first half of the green segments (3b) and (3e) ”.

  “Claim 3” is the operation method of the projection type system according to claim 1 or 2, wherein “the timing of the end of the current increasing pulse is synchronized with a predetermined position near the end of the red segment (3a) (3d)”. It is characterized by that.

"Claim 4" is a projection type system for carrying out the method of "Claim 1",
`` High-pressure discharge lamp (1) that is lit with direct current (A),
A color filter having color segments (3a) to (3f) composed of at least red, green, and blue that sequentially pass light (φ1) emitted from the high-pressure discharge lamp (1);
An optical element (4) that reflects light (φ2) that has passed through the color segments (3a) to (3f) and projects an image on the screen (7);
The current intensity of the current (A) supplied to the high-pressure discharge lamp (1) in the second half of the green segment (3b) (3e) is a current decreasing pulse that is lower than the current intensity in the first half of the green segment (3b) (3e). Synchronize the generation timing of the current decrease pulse with the synchronization signal (S) generated at a predetermined position of the green segment (3b) (3e) and synchronize the optical element (4) with the synchronization signal (S). It is composed of DC lighting means (5).

  “Claim 5” is the projection type system according to claim 4, wherein “DC lighting means (5) continues to green segment (3b) (3e), blue segment (3c) (3f) and red segment (3a)”. It further has a function of controlling the direct current (A) so that the current intensity in (3d) becomes a current increasing pulse that is increased from the current intensity in the first half of the green segments (3b) and (3e).

  “Claim 6” is the projection type system according to claim 4 or 5, wherein “DC lighting means (5) sets the end timing of the current increasing pulse to a predetermined position near the end of red segment (3a) (3d)”. It was made to synchronize. "

  In the operation method of the projection type system of the present invention, the generation timing of the current decrease pulse is synchronized with the synchronization signal generated at a predetermined position of the green segment, and the optical element is synchronized with the synchronization signal. The timing of generation of the current reduction pulse is synchronized with the optical element, and the DMD bit of the optical element driving device can be digitally processed at the exact timing in accordance with the start of the current reduction pulse, which causes image quality disturbance. Optimal image processing is possible in a transient state in the middle of the falling of the current reduction pulse. In other words, it is possible to improve fine vibration noise generated due to insufficient gradation power when minimizing image quality disturbance and expressing particularly a green component in a dark part.

  In addition, it is possible to accurately insert the current increase pulse into the subsequent blue segment and red segment in accordance with the end of the current decrease pulse. Realize gradation expression. In addition, the direct current is controlled so that the current intensity in the blue segment and the red segment continuing to the green segment is increased from the current intensity in the first half of the green segment, but this is equivalent to a pulse superimposed current waveform. Therefore, it is possible to stabilize the arc in the lamp against flicker (flickering of the screen) caused by arc jump.

  Furthermore, the end timing of the current increasing pulse is synchronized with a predetermined position near the end of the red segment. In other words, the falling edge of the current increasing pulse is arranged, for example, in a pause period at the boundary between the red and green segments. Thus, image quality disturbance can be minimized. Thereby, the DMD bit of the optical element driving device can be digitally processed in accordance with the flat portion of the current increase pulse of the blue segment and the red segment at an accurate timing. In addition, the said method can be implemented with the system of Claims 4-6.

  Hereinafter, the present invention will be described in detail according to illustrated embodiments. FIG. 1 shows an embodiment of the projection type system of the present invention. Here, for example, a projection system using a video image of 50 Hz is taken as an example. Of course, the present invention is not limited to this. In this system, a high pressure discharge lamp (1) that is mounted on a reflector (2) as a light source (E) and is lit by a DC lamp current (A) supplied from a DC lighting means (5) is used. The light emitted from 1) is reflected directly or reflected by the reflector (2) and applied to the front color filter (3).

  If an example of the color filter (3) is shown, R (red), G (green), B (blue), R (red), formed by a dichroic filter having the property of selectively passing the wavelength of visible light, A rotary disk divided into six color segments (3a) to (3f) of G (green) and B (blue), which can be rotated around its axis, and a color filter drive device (8) It is controlled to rotate at a constant speed. For example, if the video frequency is 50 Hz per frame (one screen changes at 50 times per second), for example, if the color filter (3) rotates at a triple speed, it will rotate at 150 Hz. Become. When the segments (3a), (3b), (3c) of the color filter (3) where the luminous flux (φ1) from the light source (E) is rotating at a constant speed are sequentially irradiated in time division, the color filter (3) The light (φ2) that has passed through each of the segments (3a), (3b), (3c),...

  Further, the light (φ2) that has passed through the segments (3a), (3b), (3c),... Of the color filter (3) is reflected by the surface of an optical element (4) such as a DMD and projected lens system (6 ) Creates an image on the screen (7). At this time, the light (φ3) reflected from the surface of the optical element (4) is an optical element that receives video information from the video input unit (13). Modulation is performed according to the video information supplied to the optical element (4) by the driving device (14).

  FIG. 2 shows the waveform of the DC signal (A) of the present invention and the waveform of the synchronizing signal (S) that determines the timing of the color filter (3) and the color filter (3). A synchronization signal (S) from the color filter (3) is input to the DC lighting means (5), and the start of the current decrease pulse and the end of the current increase pulse of the lamp current are controlled in synchronization with the synchronization signal (S). Hereinafter, this point will be described in detail.

  In the embodiment shown in FIG. 2, the current intensity is set to approximately 50% (50% plus or minus 5%, in this case, 1 bit can be increased) or approximately 25% (25 % Plus / minus 5%, in which case 2 bits can be increased). On the other hand, the synchronization signal (S) is input to the optical element driving device (14), and the rising timing of the synchronization signal is matched with the predetermined timing of the green segment. As a result, the DMD bit of the optical element driving device (14) can be digitally processed at the exact timing in accordance with the start of the current reduction pulse.

  In particular, an excessive region in the middle of the falling edge of the current decrease pulse is likely to cause image quality disturbance. However, by taking such synchronization, optimum image processing can be performed. There is level correction etc., and level correction can be performed accurately by matching the timing with the falling edge of the current decrease pulse. Then, by creating a flat area of current reduction pulse of approximately 50% or approximately 25%, the gradation is conventionally created with a resolution of 8 bits, while the green segment is formed at the timing of the current reduction pulse. When the light beam that has passed through is reflected by each micromirror of the DMD, a smaller bit can be created, so that reproducibility can be improved for a dark portion of the image.

  By arranging the rising edge of the current decrease pulse in a pause period at the boundary between the green and blue segments, image quality disturbance can be minimized. This has a color mixing portion at the boundary of each color segment of the color filter, and a pause time is typically provided during this period. For the subsequent blue segment and red segment, the rising timing at which the current decreasing pulse ends is used as it is, and a current increasing pulse is started to increase the current intensity from 100% in the first half of the green segment.

  Then, the current increase pulse is finished by matching the timing with the falling edge of the synchronizing signal, and the current intensity is returned to 100%. On the other hand, the synchronizing signal (S) is input to the optical element driving device (14), and the falling timing of the synchronizing signal coincides with a predetermined timing near the end of the red segment. By arranging the falling edge of the current increasing pulse in the rest period of the boundary between the red and green segments, image quality disturbance can be minimized. Thereby, the DMD bit of the optical element driving device can be digitally processed in accordance with the flat portion of the current increase pulse of the blue segment and the red segment at an accurate timing.

  Further, at this timing, the current intensity can be accurately returned to 100% in the subsequent green segment. The current increasing pulse is advantageous in terms of white balance in image processing by enhancing the current intensity in the blue and red segments. This is because the radiation spectrum of a high-pressure discharge lamp is generally difficult to produce red and blue components.

  The lamp current waveform of the current increasing pulse in the blue segment and the red segment in FIG. 2 is equivalent to the superposition of the DC pulse current having a large duty (duty). Helpful.

  According to the present invention, the image quality of the projector and the rear projection television can be improved, and the quality of the projector and the rear projection television can be greatly improved.

Block diagram of the present invention The figure which shows the relationship between the lamp current waveform of this invention, and a synchronizing signal The figure which shows the relationship between the lamp current waveform of a prior art example, and a synchronizing signal

Explanation of symbols

(A) ... DC lamp current
(E) ... Light source
(S): Sync signal
(φ) ... light
(1)… High pressure discharge lamp
(2)… Reflector
(3)… Color filter
(3a) to (3f) ... Color segment
(4) ... Optical element
(5)… DC lighting means
(6)… Projection lens system
(7)… Screen
(8)… Color filter drive device
(13)… Video input section
(14) ... Optical element driving device

Claims (6)

This is a method of operating a projection type system in which light emitted from a high-pressure discharge lamp lit with a direct current is sequentially passed through a color segment obtained by dividing a color filter into multiple segments, and then reflected on an optical element to project an image onto a screen. There,
The color filter has a plurality of filters composed of red, green and blue in sequence,
The current intensity in the second half of the green segment is a current decrease pulse that is lower than the current intensity in the first half of the green segment.
An operation method of a projection type system, characterized in that the generation timing of the current decrease pulse is synchronized with a synchronization signal generated at a predetermined position of a green segment and an optical element is synchronized with the synchronization signal.   2. The projection system according to claim 1, wherein the direct current is controlled so that the current intensity in the blue segment and the red segment continuing to the green segment becomes a current increasing pulse that is increased from the current intensity in the first half of the green segment. Actuation method.   3. The operation method of the projection type system according to claim 1, wherein the end timing of the current increasing pulse is synchronized with a predetermined position near the end of the red segment. A high-pressure discharge lamp that is lit with a direct current;
A color filter having a color segment composed of at least red, green, and blue that sequentially passes light emitted from the high-pressure discharge lamp; and
An optical element that reflects light that has passed through the color segment and projects an image on a screen;
A current reduction pulse in which the current intensity of the current supplied to the high-pressure discharge lamp in the second half of the green segment is lower than the current intensity in the first half of the green segment is generated, and the generation timing of the current reduction pulse is generated at a predetermined position of the green segment. A projection type system comprising: direct current lighting means for synchronizing with a synchronizing signal and synchronizing an optical element with the synchronizing signal.   The DC lighting means further has a function of controlling the direct current so that the current intensity in the blue segment and the red segment continuing to the green segment becomes a current increasing pulse that increases from the current intensity of the first half of the green segment. 4. The projection type system according to 4. 6. The projection type system according to claim 4, wherein the direct current lighting means synchronizes the end timing of the current increasing pulse with a predetermined position near the end of the red segment.

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