Chromaticity adjustment method and projector

Patent metadata

Field	Value
Publication number	US-12019360-B2
Application number	US-201917421998-A
Country	US
Kind code	B2
Filing date	Jan 30, 2019
Priority date	Jan 30, 2019
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

A chromaticity adjusting method of a projector includes a first light source for emitting blue light and a second light source for emitting yellow light including red light and green light. A chromaticity value of the blue light is acquired and the chromaticity value and the luminance value of each of the red light and the green light is obtained. The second target chromaticity value is determined based on the first target chromaticity value, the chromaticity value of the blue light, and the chromaticity value and the luminance value of each of the red light and the green light. Light quantities of the first and second light sources are controlled based on the second target chromaticity value. Signal levels of the red, green, and blue color components included in the video signal are controlled according to the difference between the first target chromaticity value and the second target chromaticity value.

First claim

The invention claimed is:

1. A chromaticity adjustment method of a projector comprising a light source unit that includes a first light source that emits blue light; and a second light source that emits yellow light including red light and green light, said light source unit being configured to emit a mixed light made up of the blue light and the yellow light, said projector being configured to modulate emitted light from said light source unit based on a video signal to form an image, said method comprising:
acquiring at least a chromaticity value of the blue light and obtaining a chromaticity value and a luminance value of each of the red light and the green light;
determining a second target chromaticity value based on a first target chromaticity value set in advance, the chromaticity value of the blue light, and a combination of the chromaticity value and the luminance value of each of the red light and the green light;
controlling light quantities of said first and second light sources based on the second target chromaticity value;
controlling a signal level of each color component of red, green, and blue included in the video signal in response to a difference between the first target chromaticity value and the second target chromaticity value;
calculating a chromaticity value of the yellow light based on the chromaticity value and the luminance value of the red light and the chromaticity value and the luminance value of the green light; and
obtaining, on a chromaticity diagram represented by a two-dimensional coordinate of x and y of a tristimulus value of a color stimulus, a first straight line that connects a coordinate point of the chromaticity value of the red light with a coordinate point of the first target chromaticity value, a second straight line that connects a coordinate point of the chromaticity value of the blue light with a coordinate point of the chromaticity value of the yellow light, and a third straight line that connects a coordinate point of the chromaticity value of the green light with a coordinate point of the first target chromaticity value, respectively, comparing a coordinate value of an intersection of the first straight line and the second straight line with a coordinate value of an intersection of the second straight line and the third straight line, and determining the second target chromaticity value based on the coordinate value of which a value of the y is larger.

2. The chromaticity adjustment method according to claim 1 , wherein a color temperature can be selectively set from among a plurality of color temperatures, further comprising:
setting the first target chromaticity value for each color temperature;
storing in a storage unit, for each color temperature, a driving value of each of said first and second light sources in accordance with the second target chromaticity value and a gain value of the signal of the each color component in accordance with a difference between the first target chromaticity value and the second target chromaticity value in association with each other; and
when a selection of the color temperature is made, obtaining the driving value and the gain value corresponding to the selected color temperature from said storage unit, driving said first and second light sources based on the obtained driving value, and controlling the signal level of the each color component based on the obtained gain value.

3. The chromaticity adjusting method according to claim 1 , wherein the yellow light is yellow fluorescent light.

4. A projector comprising:
a light source unit that includes a first light source that emits blue light and a second light source that emits yellow light including red light and green light, said light source unit being configured to emit a mixed light made up of the blue light and the yellow light;
an image forming means for modulating emitted light from said light source unit based on a video signal to form an image;
a projection lens that projects the image;
a control unit that controls a light quantity of each of said first and second light sources so that a chromaticity value of the emitted light of said light source unit becomes a second target chromaticity value that is determined based on a first target chromaticity value set previously, a chromaticity value of the blue light, and a combination of a chromaticity value and a luminance value of each of the red light and the green light; and that controls a signal level of each color component of red, green, and blue included in the video signal in accordance with a difference between the first target chromaticity value and the second target chromaticity value; and
a light sensor that detects a portion of the emitted light of said light source and that outputs a chromaticity value and a luminance value of each of the blue, red, and green lights,
wherein said control unit calculates, based on the chromaticity value and the luminance value of the red light and the chromaticity value and the luminance value of the green light, a chromaticity value of the yellow light obtains, on a chromaticity diagram represented by a two-dimensional coordinate of x and y of a tristimulus value of a color stimulus, a first straight line that connects a coordinate point of the red chromaticity value with a coordinate point of the first target chromaticity value, a second straight line that connects a coordinate point of the blue chromaticity value with a coordinate point of the yellow chromaticity value, and a third straight line that connects a coordinate point of the green chromaticity value with a coordinate point of the first target chromaticity value, respectively; compares a coordinate value of a intersection of the first straight line and the second straight line with a coordinate value of an intersection of the second straight line and the third straight line; and determines the second target chromaticity value based on the coordinate value of which a value of the y is larger.

5. The projector according to claim 4 , further comprising a storage unit that stores a driving value of each of said first and second light sources in accordance with the second target chromaticity value and a gain value of a signal of the each color component in accordance with a difference between the first target chromaticity value and the second target chromaticity value,
wherein the control unit drives the first and second light sources based on the driving value stored in said storage unit, and adjusts a signal level of the each color component based on the gain value stored in said storage unit.

6. The projector according to claim 5 , further comprising a color temperature setting unit that is capable of selectively setting a color temperature from among a plurality of color temperatures,
wherein the first target chromaticity value is set for each color temperature,
said storage unit stores, for the each color temperature, the respective driving values of said first and second light source in accordance with the second target chromaticity value and the gain value of the signal of the each color component in accordance with a difference between the first target chromaticity value and the second target chromaticity value,
wherein when the color temperature is selected by said color temperature setting unit, said control unit acquires a driving value and a gain value corresponding to the selected color temperature from said storage unit.

7. The projector according to claim 4 , wherein said second light source includes an excitation light source that emits blue excitation light and a phosphor that is excited by the blue excitation light and that emits yellow fluorescent light.

8. A chromaticity adjustment method of a projector comprising a light source unit

Assignees

• Sharp Nec Display Solutions Ltd

Inventors

• Ito Kaoru

Classifications

• H04N9/3182

  Colour adjustment, e.g. white balance, shading or gamut (white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607) · CPC title

• H04N9/3158

  for controlling the spectrum · CPC title

• G03B21/2013

  Plural light sources · CPC title

• G03B21/206 Primary

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

• H04N9/3194 Primary

  including sensor feedback · CPC title