A method for adjusting white balance of a laser projector

Abstract

The present invention relates to the technical field of laser projectors, and proposes a method for adjusting the white balance of a laser projector. It includes a laser light source, a fluorescent wheel, a color wheel, a display chip and a projection lens, and a photoelectric sensor is provided in the optical system between the color wheel and the projection lens. The present invention can monitor the light intensity of each picture, compare it with the initial state, and then adjust the current to prevent the white field color point / color temperature from being affected by the attenuation of the conversion efficiency of the laser fluorescence itself during long-term use, resulting in color deviation of the picture. By setting the time for automatically executing the correction program, it is also possible to perform power-on detection, timely adjustment, and ensure that each power-on is in the best state; therefore, this invention has a significant effect when applied to DLP projectors.

Description

Technical Field

[0001] The present invention relates to the technical field of laser projectors, and in particular to a method for adjusting the white balance of a laser projector. Background Art

[0002] Currently, common projectors are mainly classified into the following categories according to the type of light source used: bulbs, laser light sources, LED light sources, and laser fluorescence light sources. The laser fluorescence light source is a general term for projection display light sources involving the process of laser exciting fluorescent materials. The laser fluorescence light source has advantages such as high brightness; compared with a pure laser light source, the laser fluorescence light source has no speckle problem and lower cost. Laser fluorescence display technology also has its deficiencies. First, it sacrifices a large part of the advantages of the laser light source, such as a wider color gamut space, etc.; second, since the added phosphor system also has the characteristic of efficiency attenuation, the lifespan index of the laser fluorescence light source technology is worse than that of pure RGB products; third, the light source brightness attenuation of the laser fluorescence technology is a double attenuation of the light source + phosphor, and the steepness of its brightness decreasing curve increases much more than that of RGB products. Since the light emitted by the laser light source is a very small light spot, the very small light-emitting cross-sectional area results in only a very narrow sector area on the fluorescent color wheel participating in the light color conversion. This area receives laser irradiation with high intensity for a long time, and the chromaticity and brightness decay more severely. Projectors using laser fluorescence light sources will encounter problems such as the super-intense operation and aging of the narrow sector of the color wheel, as well as the fluorescence quenching problem of the phosphor itself. Since the excitation efficiency of the fluorescence wheel decays with time and the decay rates of each color segment are inconsistent. After a laser projector is used for a period of time, a color cast phenomenon will occur, which will cause a color deviation problem for users during use and affect the user experience. Summary of the Invention

[0003] In view of the above problems, the present invention provides a method for adjusting the white balance of a laser projector to solve the problem of color point drift of the white screen after color decay of the laser projection.

[0004] To achieve the above object, the technical solution adopted by the present invention is: a method for adjusting the white balance of a laser projector, the optical engine of the laser projector includes a laser light source (1), a fluorescence wheel (2), a color wheel (3), a display chip (4), and a projection lens (5), and a photoelectric sensor (6) is provided in the optical system between the color wheel (3) and the projection lens (5); the photoelectric sensor (6) is provided between the color wheel (3) and the display chip (4) or the photoelectric sensor (6) is provided between the display chip (4) and the projection lens (5);

[0005] The photoelectric sensor is used to detect the intensity of stray light in the optical engine during the operation of the projector. First, query the time interval since the last execution of the white balance correction program. When the set value is reached, the following steps are executed for automatic calibration:

[0006] ① Use the software tool to set the one-button automatic white balance calibration program. When executed, the platform will project the built-in images in sequence, namely red, green, blue, and yellow. Each image is displayed for 5 seconds. During this time, the photoelectric sensor will detect the stray light intensity in the optical engine of the corresponding image in sequence. The normalized ratio of the stray light intensity of each image in the optical engine is equivalent to the normalized ratio of the intensity of the projected display image.

[0007] ② Before leaving the factory, the machine will perform an automatic white balance calibration process to detect the initial stray light intensity within the optical engine of each screen. The machine stores the current settings of each screen and the stray light intensity within the optical engine of each screen in the initial mode.

[0008] ③ After a period of use, the system will check whether the set time interval has been reached during the startup process. If reached, the machine will automatically perform the white balance correction process; detect the stray light intensity within the optical engine of each screen at this time. Among the four pure color screen light intensities tested, any one can be selected as the benchmark, and then the light intensities of the other three screens are normalized;

[0009] ④ Specific adjustment process:

[0010] Use Y R实测 , Y G实测 , Y B实测 , Y C1实测 Indicates that the photoelectric sensor reads the brightness of R, G, B, C1 (Y) light;

[0011] Use Y R基准 , Y G基准 , Y B基准 , Y C1基准 Indicates the brightness of R, G, B, C1 (Y) light read by the photoelectric sensor when leaving the factory;

[0012] I R 基准 ,I G 基准 ,I B 基准 ,I C1 基准 Represents the current value;

[0013] Let r = Y R 实测 / Y R 基准

[0014] g=Y G 实测 / Y G 基准

[0015] b=Y B 实测 / Y B 基准

[0016] c1=Y C1实测 / Y C1基准

[0017] X represents the color corresponding to the minimum value among r, g, b, and c1;

[0018] Before leaving the factory, run the calibration program and use the photoelectric sensor to read the brightness Y of R, G, B, C1 (Y) light R基准 , Y G基准 , Y B基准 , Y C1基准 , current value I R 基准 ,I G 基准 ,I B 基准 ,I C1 基准 Stored in EEPROM;

[0019] After using it for a while, run the calibration program and use the photoelectric sensor to read the brightness Y of R, G, B, C1 (Y) light. R实测 , Y G实测 , Y B实测 , Y C1 实测 ;

[0020] Find the minimum value among r / g / b / c1, where X is the color corresponding to the minimum value;

[0021] a: Judgment I X实际 max whether it is established;

[0022] If established, I X实际 Set to I max , if it does not hold, then I max constant;

[0023] b: judge 0.99*(Y R 基准 / Y X基准 )≤(Y R 实测 / Y x实测 )≤(Y R基准 / Y X基准 )*1.01 is true;

[0024] If not: Determine whether (Y R 实测 / Y x实测 )>(Y R基准 / Y x基准 ) *1.01;

[0025] If the judgment result is yes, adjust I R实测 Decrease until 0.99*(Y R 基准 / Y X基准 )≤(Y R 实测 / Y x实测 )≤(Y R基准 / Y X基准 )*1.01 established;

[0026] If the judgment result is no, adjust I​R实测 Increase until 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (Y R基准 / Y X基准 ) * 1.01 holds;

[0027] c: Adjust the input current according to the above steps to obtain I R实测 、I G实测 、I B实测 、I C1实测 and other current values, and save them in the EEPROM. Use I R实测 、I G实测 、I B实测 、I C1实测 to drive the laser light source, and the adjustment is completed.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: During the use of the machine, automatic white balance correction can be performed, solving the problem of color cast of the picture caused by the attenuation of the conversion efficiency of the laser fluorescence itself during long-term use, which affects the viewing experience of users. And this solution can also achieve power-on detection and timely adjustment, that is, by adjusting the time setting for automatic correction and increasing the monitoring frequency, so that the customer gets the best picture every time they turn on the machine, giving the user the best picture experience forever. The customer can also manually execute the white balance correction program through the one-key automatic correction button set in the menu to achieve the monitoring and correction of the picture. Therefore, the present invention has significant effects when applied to DLP projectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of an optical engine of the adjustment solution one of the present invention;

[0030] Figure 2 is a schematic diagram of an optical engine of the adjustment solution two of the present invention;

[0031] Figure 3 is the first part of the schematic diagram of the adjustment solution process of the present invention;

[0032] Figure 4 is the second part of the schematic diagram of the adjustment solution process of the present invention;

[0033] Figure 5 is the third part of the schematic diagram of the adjustment solution process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The technical solution of the present invention will be described in detail below with reference to the drawings and specific embodiments.

[0035] Refer to Figures 1-5As shown, a method for adjusting the white balance of a laser projector. The optical engine of the laser projector includes a laser light source 1, a fluorescent wheel 2, a color wheel 3, a display chip 4, and a projection lens 5. An optoelectronic sensor 6 is provided in the optical system between the color wheel 3 and the projection lens 5.

[0036] As Figure 1 shown, Scheme 1: The optoelectronic sensor 6 is provided between the color wheel 3 and the display chip 4.

[0037] As Figure 2 shown, Scheme 2: The optoelectronic sensor 6 is provided between the display chip 4 and the projection lens 5.

[0038] As Figures 3-5 shown, the optoelectronic sensor is used to detect the intensity of stray light in the optical engine during the operation of the projector. First, query the time interval since the last execution of the white balance correction program. When the set value is reached, perform the following steps for automatic calibration:

[0039] ① Set the one-key automatic white balance correction program through a software tool (software). During the execution, the machine will project the built-in images in sequence, namely red, green, blue, and yellow; each image is displayed for 5s. During this period, the optoelectronic sensor will detect the intensity of stray light in the optical engine corresponding to each image in sequence; the normalized ratio of the stray light intensity of each image in the optical engine is equivalent to the normalized ratio of the projection display image intensity.

[0040] ② Before leaving the factory, the machine will execute a white balance automatic correction program once to detect the initial intensity of stray light in the optical engine for each image; the machine stores the current settings for each image and the intensity of stray light in the optical engine for each image in the initial mode.

[0041] ③ After using it for a period of time, during the startup process, the system will query whether the machine has reached the set time interval. After reaching it, the machine will automatically execute the white balance correction program; detect the intensity of stray light in the optical engine for each image at this time. For the light intensities of the four pure color images tested, any one can be selected as the reference, and then the light intensities of the other three images are normalized.

[0042] ④ Adjustment specific process:

[0043] Use Y R实测 , Y G实测 , Y B实测 , Y C1实测 to represent the brightness of the R, G, B, and C1(Y) lights read by the optoelectronic sensor;

[0044] Use Y R基准 , Y G基准 , Y B基准 , Y C1基准 to represent the brightness of the R, G, B, and C1(Y) lights read by the optoelectronic sensor at the time of leaving the factory;

[0045] I R 基准 、I G 基准 、I B 基准 、I C1 基准 represent the current value;

[0046] Let r = Y R 实测 / Y R 基准

[0047] Let g = Y G 实测 / Y G 基准

[0048] Let b = Y B 实测 / Y B 基准

[0049] Let c1 = Y C1实测 / Y C1基准

[0050] X represents the color corresponding to the minimum value among r, g, b, and c1;

[0051] Before leaving the factory, run the calibration program and use the photoelectric sensor to read the brightness Y of R, G, B, and C1(Y) light R基准 、Y G基准 、Y B基准 、Y C1基准 , the current value I R 基准 、I G 基准 、I B 基准 、I C1 基准 and save them in the EEPROM;

[0052] After using it for a period of time, run the calibration program and use the photoelectric sensor to read the brightness Y of R, G, B, and C1(Y) light R实测 、Y G实测 、Y B实测 、Y C1 实测 ;

[0053] Find the minimum value among r / g / b / c1, and X is the color corresponding to the minimum value;

[0054] a: Judge I X实际 <I max whether it holds;

[0055] If it holds, set I X实际 to I max , if it doesn't hold, I max remains unchanged;

[0056] b: Judge 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (YR基准 / Y X基准 ) * 1.01 holds;

[0057] If not: Determine whether (Y R 实测 / Y x实测 ) > (Y R基准 / Y x基准 ) * 1.01;

[0058] If the judgment result is yes, adjust I R实测 to decrease until 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (Y R基准 / Y X基准 ) * 1.01 holds;

[0059] If the judgment result is no, adjust I R实测 to increase until 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (Y R基准 / Y X基准 ) * 1.01 holds;

[0060] c: Adjust the input current according to the above steps to obtain I R实测 , I G实测 , I B实测 , I C1实测 and other current values, and save them in the EEPROM. Use I R实测 , I G实测 , I B实测 , I C1实测 to drive the laser light source, and the adjustment is completed.

[0061] The above adjustment is based on Y i实测 / Y i基准 , where Yi实测 is the currently measured illuminance value of each screen, and Y i基准 is the initial illuminance value of each screen. It can be known which screen among red R / green G / blue B / yellow C1 has the largest attenuation amplitude, and assign it as X, where i represents the four pure color screens tested; Determine whether the set current Ix of the screen with the largest illuminance attenuation amplitude at this time is the largest, that is, adjust the current of the screen X with the largest current illuminance attenuation amplitude to the largest to obtain the measured illuminance value Y x实测 at this time; Through 0.99 Y i基准 / Y x基准 ≤ Y i实测 / Y x实测 ≤ 1.01 Y i基准 / Yx基准 Adjust the current of i at this time according to the judgment condition to make it meet the condition; where Y x基准 is the initial illuminance value of the current frame with the largest illuminance attenuation amplitude, and Y x实测 is the currently measured actual illuminance value of the current frame with the largest illuminance attenuation amplitude, that is, to make the normalized ratio of the light intensity of each color at this time equal to the normalized ratio of the light intensity of each color of the initial reference, so as to keep the color temperature / color point of the white frame at the initial value. Each time the current of the i / X frame is adjusted, the machine will project the corresponding built-in frame, that is, the light intensity of the stray light in the optical engine of the corresponding adjusted frame is measured in real time.

[0062] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A white balance adjustment method for a laser projector, wherein the optical engine of the laser projector includes a laser light source (1), a fluorescence wheel (2), a color wheel (3), a display chip (4), and a projection lens (5), and is characterized in that, An optoelectronic sensor (6) is provided in the optical system between the color wheel (3) and the projection lens (5); the optoelectronic sensor (6) is provided between the color wheel (3) and the display chip (4) or the optoelectronic sensor (6) is provided between the display chip (4) and the projection lens (5); The optoelectronic sensor is used to detect the intensity of stray light in the optical engine during the operation of the projector. First, query the time interval since the last execution of the white balance correction program. When the set value is reached, perform the following steps for automatic calibration: ① Set the one-key automatic white balance correction program through software tools. When the machine is running, it will project the built-in pictures in sequence, namely red, green, blue, and yellow; the display time of each picture is 5s. During this period, the optoelectronic sensor will detect the intensity of stray light in the optical engine corresponding to each picture in sequence; the normalized ratio of the stray light intensity of each picture in the optical engine is equivalent to the normalized ratio of the projection display picture intensity; ② Before leaving the factory, the machine will execute a white balance automatic correction program to detect the initial illumination intensity of stray light in the optical engine of each picture; the machine stores the current settings of each picture and the illumination intensity of stray light in the optical engine of each picture in the initial mode; ③ After using it for a period of time, during the startup process, the system will query whether the machine has reached the set time interval. After reaching it, the machine will automatically execute the white balance correction program; detect the intensity of stray light in the optical engine of each picture at this time. For the light intensity of the four pure color pictures tested, any one can be selected as the reference, and then the light intensities of the other three pictures are normalized; ④ Adjustment process: Use Y respectively R实测 、 Y G实测 、 Y B实测 、 Y C1实测 to represent the brightness of the light of R, G, B, and C1(Y) read by the photoelectric sensor; Use Y respectively R基准 、Y G基准 、Y B基准 、Y C1基准 to represent the brightness of the R, G, B, and C1(Y) lights read by the photoelectric sensor at the time of factory shipment; I R 基准 、I G 基准 、I B 基准 、I C1 基准 represent current values; Let r = Y R 实测 / Y R 基准 g = Y G 实测 / Y G 基准 b = Y B 实测 / Y B 基准 c1=Y C1实测 / Y C1基准 X represents the color corresponding to the minimum value among r, g, b, and c1; Before leaving the factory, run the calibration program and use a photoelectric sensor to read the brightness Y of R, G, B, and C1(Y) light R基准 , Y G基准 , Y B基准 , Y C1基准 , the current value I R 基准 , I G 基准 , I B 基准 , I C1 基准 Save them in the EEPROM; After using for a period of time, run the calibration program and use a photoelectric sensor to read the brightness Y of R, G, B, and C1(Y) light R实测 , Y G实测 , Y B实测 , Y C1 实测 ; Find the minimum value among r / g / b / c1, and X is the color corresponding to the minimum value; a: Judgment I X实际 <I max Is it established? If it holds, set I X实际 to I max , if it does not hold, I max remains unchanged; b: Determine if 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (Y R基准 / Y X基准 ) * 1.01 holds; When it does not hold: Determine whether (Y R 实测 / Y x实测 ) > (Y R基准 / Y x基准 ) * 1.01; If the judgment result is yes, then adjust I R实测 Decrease until 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (Y R基准 / Y X基准 ) * 1.01 holds; If the judgment result is no, then adjust I R实测 Increase it until 0.99 * (Y R 基准 / Y X基准 ) ≤ (Y R 实测 / Y x实测 ) ≤ (Y R基准 / Y X基准 ) * 1.01 holds; c: Adjust the input current according to the above steps to obtain I R实测 , I G实测 , I B实测 , I C1实测 and other current values, and save them in the EEPROM. Use I R实测 , I G实测 , I B实测 , I C1实测 to drive the laser light source, and the adjustment is completed.

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