Image projecting apparatus and image projecting method

• US 7,967,445 B2
• Filed: 11/13/2007
• Issued: 06/28/2011
• Est. Priority Date: 11/16/2006
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Hamano, Yukiko, Kasahara, Ryosuke, Kawasaki, Toshiyuki
• Primary Examiner(s): Epps; Georgia Y
• Assistant Examiner(s): CHOWDHURY, SULTAN U.
• Application Number:
  US11/939,520
• Publication Number:
  US 20080117387A1
• Time in Patent Office: 1,323 Days
• Field of Search: 353/85, 353/97, 353/69, 353/34, 353/28, 353/31, 353/70, 353/122, 382/162, 382/167, 382/254, 382/274, 382/275, 359/9, 359/21, 359/32, 359/33, 359/15, 359/10, 359/11, 359/23, 359/237, 359/242, 359/259, 359/263, 348/745, 348/744, 348/806, 348/807, 348/813, 348/E17.001, 348/E17.006, 348/E5.137, 348/E9.012, 362/318, 362/293, 362/294, 362/321
• US Class Current: 353/31
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 27/545 for enlargers
• CPC Class Codes: H04N 2005/745 Control circuits therefor
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 9/3102 using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3173 wherein the projection device is specially adapted for enhanced portability
• CPC Class Codes: H04N 9/3179 Video signal processing therefor
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

An image projecting apparatus enables the formation of a projected image faithful to original image information by reducing degradation in the projected image due to decrease in imaging performance of a projection optical system. Image information is processed by an image processing device, which includes a first and a second image processor. A light modulating device modulates a flux of light emitted by an illumination optical system based on the processed image information. The modulated flux of light is projected on a screen by a projection optical system. If the image information processed by the first image processor in a pixel region is not within a representable modulation range of the light modulating device, the image information is processed by the second image processor.

Claims

1. An image projecting apparatus, comprising:

an illumination optical system configured to emit a flux of light;

an image processing device configured to process image information;

a light modulating device configured to modulate the flux of light emitted by the illumination optical system based on the image information processed by the image processing device; and

a projection optical system configured to project the flux of light modulated by the light modulating device on a screen to form a projected image;

wherein the image processing device comprises

a first image processor configured to process the image information on a pixel unit region basis, each pixel unit consisting of one or more pixels, so as to compensate for degradation in the image projected by the projection optical system;

a determination unit configured to determine whether the image information processed by the first image processor on a pixel unit region basis is within a representable modulation range of the light modulating device; and

a second image processor configured to process a part of the image information in a pixel region that is determined to lie outside the representable range;

wherein the second image processor converts the part of the image information in the pixel region determined to lie outside the representable modulation range back to its original image information prior to the image processing by the first image processor; and

plural image processing devices, one for each of two or more colors,

wherein, in a pixel region where the part of the image information processed by the first image processor of a first image processing device for a first color is not within the representable modulation range, the second image processor of the first image processing device converts the part of the image information in the aforementioned pixel region back to its original image information prior to the image processing by the first image processor of the first image processing device,

and the second image processor of a second image processing device for a second color processes a part of the image information for the second color processed by the first image processor of the second image processing device that is in the same aforementioned pixel region with the same ratio of change as the ratio of change introduced into the part of the image information for the first color in the pixel region by the processing by the second image processor of the first image processing device.

3. The image projecting apparatus according to claim 1, wherein the illumination optical system comprises a light-amount distribution controller configured to control the distribution of light amount in the cross section perpendicular to the light flux.

2. An image projecting apparatus, comprising:

an illumination optical system configured to emit a flux of light;

an image processing device configured to process image information;

a light modulating device configured to modulate the flux of light emitted by the illumination optical system based on the image information processed by the image processing device; and

a projection optical system configured to project the flux of light modulated by the light modulating device on a screen to form a projected image;

wherein the image processing device comprises

a first image processor configured to process the image information on a pixel unit region basis, each pixel unit consisting of one or more pixels, so as to compensate for degradation in the image projected by the projection optical system;

a determination unit configured to determine whether the image information processed by the first image processor on a pixel unit region basis is within a representable modulation range of the light modulating device; and

a second image processor configured to process a part of the image information in a pixel region that is determined to lie outside the representable range;

wherein the second image processor allocates an upper limit value of the representable modulation range to the part of the image information that exceeds an upper limit of the representable modulation range, and allocates a lower limit value to the part of the image information that drops below a lower limit of the representable modulation range; and

plural image processing devices, one for each of two or more colors,

wherein, in a pixel region where the part of the image information processed by the first image processor of a first image processing device for a first color is not within the representable modulation range, the second image processor of the first image processing device allocates an upper limit value to a part of the image information that exceeds an upper limit of the representable modulation range, and allocates a lower limit value to a part of the image information that drops below a lower limit of the representable modulation range,

wherein the second image processor of a second image processing device for a second color processes a part of the image information for the second color processed by the first image processor of the second image processing device that is in the same aforementioned pixel region with the same ratio of change as the ratio of change introduced into the part of the image information for the first color in the pixel region by the processing by the second image processor.

4. The image projecting apparatus according to claim 2, wherein the illumination optical system comprises a light-amount distribution controller configured to control the distribution of light amount in the cross section perpendicular to the light flux.

5. A method for projecting an image on a screen using an image projecting apparatus comprising an illumination optical system configured to emit a flux of light, an image processing device configured to process image information, a light modulating device configured to modulate the flux of light emitted by the illumination optical system based on the image information processed by the image processing device, and a projection optical system configured to project the flux of light modulated by the light modulating device onto the screen to form a projected image,

the method comprising:

a first image processing step of processing the image information on a pixel unit region basis, each unit consisting of one or more pixels, so as to compensate for degradation in the projected image projected by the projection optical system;

a determination step of determining whether the image information processed by the first image processing step on a pixel unit region basis is within a representable modulation range of the light modulating device; and

a second image processing step of processing the part of the image information in a pixel region that is determined to be outside the representable modulation range in the determination step; and

wherein the second image processing step comprises converting the part of the image information back to its original image information prior to the first image processing step.