JP4878797B2 - Time-varying correction device for projection display - Google Patents

Description

  The present invention relates to a temporal change correction apparatus for a projection display.

  2. Description of the Related Art Conventionally, in an apparatus for correcting a change in white balance with time as described in Japanese Patent Application Laid-Open No. 9-37281 (Patent Document 1) in a projection display, white caused by deterioration of CRT phosphor, reduction of cathode emission, etc. In order to compensate for changes in balance over time, an optical sensor is installed in the overscan part of the screen, and a reference signal with a constant R, G, B signal level is generated on the optical sensor in the overscan part. Was measuring. Then, the deviation from the initial adjustment value of the luminance measurement value of the reference signal is calculated, and correction is performed by controlling the output of the light source. However, since such a conventional technique uses a small area of the overscan portion of the screen, there is a problem that the peripheral light amount ratio and the screen unevenness cannot be considered, and correct correction cannot always be performed.

In order to solve this and make it possible to always correct the change over time correctly, measure the amount of light for the image where the RGB signal level is uniform in the region where the light sensor measures the amount of light, It is necessary to determine the rate of deterioration of and compensate for this. Alternatively, the degree to which light from each part of the screen reaches the optical sensor is calculated in advance as a contribution, an average signal is calculated in consideration of this contribution, and the deterioration rate from the initial value is obtained using the obtained average signal. And the light source needs to be controlled to compensate for this.
JP-A-9-37281

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a time-varying correction apparatus that can always correct the white balance of a projection display correctly.

Projection display according to an aspect of the present invention, a light amount measurement unit for measuring the quantity of movies image projection display using the RGB light source by the optical sensor, the input image corresponding to the area to be measured by the light sensor in realm, and it determines uniform distribution determining unit whether RGB signal indicates a uniform distribution, when the RGB signal is determined to indicate a uniform distribution in the uniform distribution determining unit, by the light sensor measured light amount and a memory storing the RGB signal value of the corresponding region of the input image at that time, the initial adjustment value storage unit that stores the RGB light amount at the time of initial adjustment, the amount of light and RGB stored in the memory The deterioration rate is calculated by comparing the RGB light amounts calculated from the relationship with the signal value with the RGB light amounts at the time of initial adjustment stored in the initial adjustment value storage unit. A rate computation unit and is characterized by comprising a light source control section for controlling the output of the other light source colors to align the output of the light source color that indicates the most advanced degradation rates of the RGB light source .

In one feature, the light amount measurement unit measures the light amount with the optical sensor when the projection display is displaying a black image, stores it in the memory as an external light amount, and the deterioration rate calculation unit includes: The value obtained by subtracting the external light amount from the measured light amount is used as the actual light amount, and the RGB light amounts calculated from the relationship between the actual light amount and the RGB signal values, and the initial adjustment value stored in the initial adjustment value storage unit. The deterioration rate may be calculated by comparing the amount of RGB light at that time.

A projection display according to another aspect of the present invention includes a light amount measuring unit that measures a light amount of an image projected on a screen from a projection display using an RGB light source by an optical sensor, and the optical sensor from each pixel position of the screen in advance. A degree-of-arrival contribution storage unit that stores the contribution degree of light arrival to the pixel, and an average signal calculation unit that calculates an average RGB signal value for each pixel of the input image using the contribution degree for each pixel of the contribution degree storage unit And a memory for storing the light amount measured by the optical sensor and the average RGB signal value at that time, and an initial adjustment for storing the RGB light amount at the time of initial adjustment for the screen on which the input image is projected a value storage unit, and the quantity of RGB each calculated from the relationship between the average RGB signal value light quantity stored in the memory, the initial adjustment By comparing the RGB light amount at the time of initial adjustment in the storage unit stored with the deterioration rate calculator for calculating a deterioration rate, other so as to align the output of the light source color that indicates the most advanced degradation rates of the RGB light source And a light source control unit for controlling the output of the light source color.

In this feature, the light amount measurement unit measures the light amount with the optical sensor when the projection display is displaying a black image, and stores it in the memory as an external light amount. the value obtained by subtracting the outer light amount from the measured amount and the real amount of light, the real amount of light to the average light amount of the respective RGB calculated from the relationship between the RGB signal values, initial adjustment stored in the initial adjustment value storage unit The deterioration rate may be calculated by comparing the amount of RGB light at that time .

In the above projection display, a black image may be projected when the power is turned on or when the image is switched, and the external light amount may be measured by the optical sensor.

Further, in the above projection display, a brightness correction amount calculation unit that estimates brightness around the projection display based on the external light amount and instructs the light source control unit to correct the amount according to the surrounding brightness. You may prepare.

Further, in the projection display, the deterioration rate calculation unit may calculate a deterioration rate in consideration of a light source control amount of each of the RGB light sources.

In another aspect of the projection display, the deterioration rate calculation unit includes a light amount not including the external light amount and the RGB signal based on a relationship between a light amount obtained by subtracting an arbitrary external light amount from the light amount stored in the memory and the RGB signal value. The respective RGB light amounts are obtained from the derived relational expressions, and the deterioration rate is calculated by comparing the obtained RGB light amounts with the RGB light amounts at the time of initial adjustment stored in the initial adjustment value storage unit. It may be calculated.

According to the projection Display b of the present invention, always performed correctly correction of the change of white balance over time in consideration of the relative illumination and screen irregularities.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (First Embodiment) FIGS. 1 and 2 are a functional configuration of a display temporal change correction apparatus according to an embodiment of the present invention, and an element arrangement diagram of a rear projection type projection display 100 employing the same. As shown in FIG. 2, the rear projection type projection video monitor 100 includes an RGB light source 13 capable of individually controlling RGB light source colors, a lens 14 for enlarging video light from the light source 13, and an image from the lens 14. A mirror 12 that reflects light and a screen 11 that forms an image reflected from the mirror 12 are provided. Further, the optical sensor 10 is installed at an appropriate position with respect to the screen 11 so that the light quantity in a partial area of the screen 11 is always measured. For the RGB light source 13, for example, an LED or a laser is employed.

  In FIG. 2, the optical sensor 10 is arranged at one appropriate position on the screen 11, but a plurality of optical sensors 10 may be installed at appropriate positions in the vertical direction or in the horizontal direction so as not to be a shadow of the projected image. In this case, the light amount of each sensor can be individually used as the light amount used for the arithmetic processing. And the installation position and the number of installation of this sensor are equally applicable also in the following other embodiment.

  As shown in FIG. 1, the display aging correction apparatus of the present embodiment includes a light source 13 that projects backlight light on a screen 11, a light source control unit 21 that controls the luminance of the light source 13, and input image data 31. A uniform distribution determination unit 22 that determines a uniform distribution region, a light amount measurement unit 23 that measures a light amount based on a signal from the sensor 10 that detects the luminance of the screen 11, and an initial adjustment value storage unit 24 that stores initial adjustment value data. The light source deterioration rate is calculated from the memory 25 that temporarily holds the calculated value, the measured light amount output from the light amount measuring unit 23, and the initial adjustment value held in the initial adjustment value storage unit 24, and is stored in the memory 25. In addition, the light source control unit 21 is provided with a deterioration rate calculation unit 26 that outputs light source control.

The white balance aging correction operation by the display aging correction apparatus of the above embodiment will be described. FIG. 3 is a flowchart of the temporal change correction processing according to this embodiment. First, in order to determine whether or not the region in which the light amount is measured by the optical sensor 10 is a uniform distribution region, the uniform distribution determination unit 22 calculates the variance v of the histogram of the corresponding region from the input image data (step S1). ). There are two methods for discriminating whether or not the RGB signal has a uniform distribution: a method of discriminating from histogram variance and a method of discriminating from cumulative addition of high-frequency components. In this embodiment, discrimination is made from histogram variance. . For this purpose, an average luminance and a luminance histogram of the area being measured of the input image are created. When the number of pixels in the region is N, the maximum luminance level is Max, and the frequency of the histogram for the luminance level n is H [n], the average luminance ave and the variance v are calculated by the following equations.

  If the calculated variance v is smaller than a certain value, it is determined that the RGB signal shows a uniform distribution in that region (step S3). When it is determined that the RGB signal shows a uniform distribution, the uniform distribution determination unit 22 stores the values (R, G, B) of the RGB signal at that time in the memory 25, and the light quantity measurement unit 23 is an optical sensor. The light quantity L is measured from the signal detected by 10 and stored in the memory 25 (step S5). The uniform distribution determination unit 22 and the light amount measurement unit 23 measure the relationship between the RGB signal value (R, G, B) and the light amount L in the region where the RGB signal shows a uniform distribution, also for other video data. Then, three relational expressions are calculated (step S7). Then, after calculating the three relational expressions, the deterioration rate calculation unit 26 estimates the light amount of only the RGB signals using the data held in the memory 25 (step S9), and further each RGB at the time of initial adjustment The deterioration rate is calculated in comparison with the amount of light (step S11).

Here, the light quantity of R is x, the light quantity of G is y, and the light quantity of B is z. First, the RGB signals in the scene 1 in the input image data are (R1, G1, B1), and the measured light quantity at that time is L1. The relationship at this time is shown in Formula (3). Similarly, Equation (4) shows the relationship between the RGB signals (R2, G2, B2) and the measured light quantity L2 for the scene 2, and Equation (5) shows the RGB signals (R3, G3, B3) for the scene 3. And the relationship between the measured light quantity L3.

Equation (6) is calculated from the relationship between scenes 1 and 2, and equation (7) is calculated from the relationship between scenes 1 and 3.

Equation (8) is derived from the calculated equations (6) and (7), and the light quantity x for R is given by equation (9).

Similarly, the light quantities y and z for G and B are expressed by equations (10) and (11).

As described above, after calculating the light amounts of only R, G, and B, the deterioration rate (in accordance with the following formula) is compared with the light amounts of R, G, and B (x ₀ , y ₀ , z ₀ ) at the time of initial adjustment. Ix, Iy, Iz) is calculated.

  The degradation rate calculation unit 26 controls the output of other light sources so as to match the white balance with reference to the light source that exhibits the minimum degradation rate among the degradation rates calculated in this way, and thus the light source that has progressed the maximum. Is output to the light source controller 21 (step S13). Then, the light source control unit 21 controls the light source 13 based on the light source control amount that matches the white balance received from the deterioration rate calculation unit 26 (step S15).

Here, when the minimum deterioration rate is _Iz , the light source control amounts C _R , C _G , and C _B of _R , _G , and _B are as follows. That is, the light source output is controlled so that the other light source colors are aligned with the light source color having the greatest deterioration.

In addition to the light amount at the time of initial adjustment, the light source control amount at the time of initial adjustment is also stored in the memory 25 in advance, and when the light source is controlled at the time of initial adjustment, the light source control amount is also taken into consideration, In place of the R, G, and B light source control amounts C _R , C _G , and C _B obtained by the equations (15) to (17), the following equations (15A) to (17A) are calculated, and the final calculation is performed. Control amounts C _R , C _G , and C _B are obtained, and the light source output can be controlled based on them. Here, the light source control amounts at the time of initial adjustment are A _R , A _G , and A _B, and I _z obtained above is the minimum deterioration rate.

  According to the temporal change correction apparatus of the present embodiment, the optical sensor is installed at a position that does not affect the projected image, the light amount in the region where the RGB signal is uniformly distributed on the screen surface is measured, and the RGB signal value and this Estimate the light quantity of each RGB from the relational expression with the measured light quantity, obtain the deterioration rate of each RGB from the ratio of this to the RGB initial adjustment value, and further output the light source color indicating the minimum deterioration rate among the RGB light sources Since the output of other light source colors is controlled so as to be aligned, it is possible to always correct white balance over time while measuring the amount of light on the screen surface on which the actual image is projected, which is not the overscan unit.

  The light sensor 10 is installed at an upper position of the screen 13 that is not easily affected by the ceiling light, so that the white balance aging correction is always correct by a simple calculation while ignoring the influence of the external light. Yes.

  (Second Embodiment) In the first embodiment, when controlling the light source from the deterioration rate (Ix, Iy, Iz), the control amount is determined based on the light source control amount and the deterioration rate of each of the RGB light sources. .

  For example, the R, G, and B light amounts are controlled to 70%, 100%, and 80% during initial adjustment, and the deterioration rates of R, G, and B are 50%, 80%, and 60%. Let the initial light intensity be x, y, z. In the case of the first embodiment, the control amount in consideration of the deterioration rate is 1.0 (0.5 / 0.5), 0.625 (0.5 / 0.8), 0.833 (0.5 /0.6), the corrected light amount is 0.5x, 0.5y, 0.5z, and the corrected light source control amount is 70% (70% × 1), 62.5% (100% × 0. 625), 66.6% (80% × 0.833).

  In the second and subsequent times, when the measurement light quantity becomes 0.3x, 0.4y, and 0.35z, the deterioration rates from the initial adjustment are 30% (0.3x / x) and 40% (0.4y / y). ), 35% (0.35 z / z). The control amount considering the deterioration rate is 1.0 (0.3 / 0.3), 0.75 (0.3 / 0.4), 0.86 (0.3 / 0.35), and is corrected. The subsequent light amounts are 0.3x, 0.3y, and 0.3z, and the corrected light source control amounts are 70% (70% × 1), 46.9% (62.5% × 0.75), and 57.3. % (66.6% × 0.86).

  However, in consideration of the light source control amount, when a deteriorated light source is output to 100%, 0.71x (0.5x / 0.7), 0.8y (0.8x / 1.0), 0.75z (0 0.7 / 0.8), 0.71x is a value indicating the minimum deterioration rate. Therefore, the control amount in consideration of the deterioration rate is 1.0 (0.71x / 0.71x), 0.888 (0.71y / 0.8y), 0.947 (0.71z / 0.75z). . Therefore, the corrected light amount is 0.71x, 0.71y, 0.71z, and the corrected light source control amount is 100% (100 × 1.0), 88.8% (100 × 0.888), 94. 7% (100 × 0.947).

  When correcting again after the second time, the deterioration rate is 40.0% (0.4x / x), 60.0% (0.6y / y), 50.0% (0.5z / z). When the deteriorated light source is output to 100%, 0.4x (0.4x / 1.0), 0.68y (0.6y / 0.888), 0.53z (0.5z / 0.947) Therefore, 0.4x is a value indicating the minimum deterioration rate. Therefore, the control amount in consideration of the deterioration rate is 1.0 (0.4x / 0.4x), 0.588 (0.4y / 0.68y), and 0.755 (0.4z / 0.53z). . Therefore, the corrected light amount is 0.4x, 0.4y, 0.4z, and the corrected light source control amount is 100% (100 × 1.0), 58.8% (100 × 0.588), 75. 5% (100 × 0.755).

  Thus, the power of the light source can be effectively utilized by considering the light source control amount.

Therefore, the temporal change correction apparatus of the second embodiment additionally has a function in which the deterioration rate calculation unit 26 considers this light source control amount in the same configuration as that of the first embodiment shown in FIG. It is characterized by having. Therefore, the deterioration rate calculation unit 26 additionally executes the following calculation process in step S13 in the flowchart of FIG. 3, and outputs a control amount considering the light source control amount to the light source control unit 21 and after correction. Are stored in the memory 25. In other words, the light source control amounts of the RGB light sources are A _R , A _G , and A _B , and I _z indicates the minimum deterioration rate in consideration of the light source control amount as in the first embodiment. The deterioration rate calculation unit 26 calculates the control amounts of R, B, and G by the equations (15 ′) to (17 ′) with respect to the equations (15) to (17), and supplies the light source control unit 21 with the control amounts. Output.

  Even in this embodiment, it is desirable that the optical sensor 10 be installed at an upper position of the screen 13 that is not easily affected by external light.

  (Third Embodiment) The temporal change correction apparatus of the third embodiment has the same configuration as that of the first embodiment shown in FIG. 1, but the RGB signal executed by the uniform distribution determination unit 22. Unlike the first embodiment, the uniform distribution region determination process uses the accumulation of high-frequency components. Accordingly, all other components are common to the first embodiment. Hereinafter, the characteristic part will be described.

In the flowchart of FIG. 4, as shown in step S <b> 1-1, the uniform distribution determination unit 22 calculates high-frequency components in four directions (horizontal, vertical, and two diagonal directions) with respect to input image data. The high-frequency components HPF _h (horizontal direction), HPF _v (vertical direction), HPF _d1 , (diagonal direction 1), and HPF _d2 (diagonal direction 2) of the pixel of interest (i, j) are expressed by the following equation (18): Calculated from (21).

Next, as shown in step S1-2, among the values calculated from the equations (18) to (21), the minimum value M [i, j] is set as the high frequency component of the target pixel, and the measurement is performed in the region ( The cumulative addition value HPF of the high frequency components (0 ≦ i ≦ m, 0 ≦ j ≦ n) is calculated by the following equation (22).

  Further, as shown in step S <b> 3 ′, when the calculated cumulative addition value HPF of the high frequency components is smaller than a certain value, the uniform distribution determination unit 22 determines that the RGB signal has a uniform distribution in that region. The processes after step S5 are the same as those in the first embodiment.

  According to the third embodiment, the same effect as that of the first embodiment can be obtained. Even in the third embodiment, it is possible to add a function that considers the amount of suppression of the light amount at the time of initial adjustment as in the second embodiment, thereby further increasing the power of the light source. Can be used for

  (Fourth Embodiment) FIG. 5 is a block diagram of a time-varying correction apparatus using the degree of contribution according to a fourth embodiment of the present invention. Similar to the first embodiment, the temporal change correction apparatus of the present embodiment includes a light source 13, a light source control unit 21, a light amount measurement unit 23, a distance adjustment value storage unit 24, a memory 25, and a deterioration rate calculation unit 26. And an average signal value calculation unit 22-1 in place of the uniform distribution determination unit 22, and a contribution storage unit 27. In FIG. 5, other elements common to the first embodiment are denoted by the same reference numerals as those used in FIG. 1.

Next, the white balance correction process according to the present embodiment will be described with reference to FIGS. The contribution C _ij of each pixel (i, j) of the screen 11 is calculated by a method described later, and the data is stored in the contribution recording unit 27 (step S2-1). Then, the average signal value calculation unit 22-1 calculates an average signal value RGB signal value (Rt, Gt, Bt) in consideration of the contribution degree to any scenes 1 to 3 of the input image data, and saves it in the memory 25. (Step S2-2). The light quantity measuring unit 23 measures the light quantity L in each scene and stores it in the memory 25 (step S5). If there are three relational expressions between the RGB signal values and the light amount stored in the memory 25, the process proceeds to the next process (step S7).

The deterioration rate calculation unit 26 uses the average signal (Rt, Gt, Bt) calculated by the average signal value calculation unit 22-1 and the light amount L measured by the light amount measurement unit 23, and calculates the RGB light amount ( x, y, z) is calculated, the deterioration rate is calculated by comparison with the initial adjustment values (x ₀ , y ₀ , z ₀ ), and the light source control unit 21 controls the power of each RGB light source (steps S9 to S9). S15).

A method of calculating an average RGB signal from the contribution degree of light projected on the screen 11 of the projection display will be described. First, each pixel on the screen 11 is turned on at 100% power in order, and the light quantity at that time is measured by the optical sensor 10 to calculate the contribution C _ij of each pixel as shown in FIG. The contribution is large near the optical sensor 10, and the contribution is low as the distance increases.

The average signal value (Rt, Gt, Bt) in consideration of the contribution degree _Cij in an arbitrary video for each pixel is expressed by equations (23) to (25). Here, the number of pixels in the horizontal direction of the video is I, the number of lines in the vertical direction is J, the contribution for the pixel of interest (i, j) is C _ij , and the RGB signal values are R _ij , G _ij , B _ij. And

In the average signal value calculation unit 22-1, the above equations (23) to (25) are obtained for arbitrary scenes 1 to 3. On the other hand, the light quantity L for each scene is measured by the light sensor 10 and the light quantity measuring unit 21. Then, the deterioration rate calculation unit 26 calculates the amount of light (x, y, z) for each of RGB from the obtained three relational expressions in the same manner as in the first embodiment. Further, the deterioration rate calculation unit 26 obtains the deterioration rate based on the ratio with the initial adjustment values (x ₀ , y ₀ , z ₀ ), and the deterioration of the light source color indicating the minimum deterioration rate as in the first embodiment. A control command for aligning the light amounts of other light source colors is output to the light source control unit 21, and the RGB light source 13 is controlled by the light source control unit 21 to correct the white balance.

  According to the present embodiment, as in the first embodiment, the amount of light on the screen surface other than the overscan portion is measured, and the average RGB signal and the amount of light considering the non-uniformity of the measurement amount by the optical sensor are calculated. By calculating the relationship, it is possible to estimate the amount of light for each of RGB, and to correct the change over time in consideration of the peripheral light amount ratio and screen unevenness.

  Even in the present embodiment, when the initial control value of each light source color is not 100% as in the second embodiment relative to the first embodiment, the current deterioration rate is set to 100%. It is possible to prevent the screen from becoming too dark with white balance correction by increasing the amount of light emission accordingly. Also in the present embodiment, it is desirable that the optical sensor 10 be installed at an upper position of the screen 13 that is not easily affected by external light.

  (Fifth Embodiment) Although it depends on the position of the sensor for measuring the amount of light, it is necessary to consider the influence of external light in order to correct the change over time in the general environment. The projection display temporal change correction apparatus according to the fifth embodiment of the present invention has a function of automatically correcting white balance in consideration of external light reaching the screen 11, and as shown in FIG. Instead of the light quantity measurement unit 23 and the deterioration rate calculation unit 26 in the embodiment, a light quantity measurement unit 23 ′ additionally having a function of measuring external light, and deterioration of each light source color after removing the influence of external light And an outside light / deterioration rate calculation unit 26 ′ for calculating the rate.

  The white balance correction processing by the temporal correction apparatus of the present embodiment is based on the flowcharts of FIGS. First, as in Step S100 of FIG. 9 and Steps S101 and S103 of FIG. 10, the light quantity measurement unit 23 ′ projects a black image on the screen 11 when the power is turned on or when the user switches the image (Step S100). S105). Then, the light amount a at that time is measured, and this is stored in the memory 25 as the external light amount a (step S107).

  Thereafter, similarly to the first embodiment, the uniform distribution determination unit 22 determines the uniform distribution region of the scenes 1 to 3 (steps S1 and S3), and the light amount measurement unit 23 ′ determines the light amount L in the corresponding scenes 1 to 3. Are measured to create three relational expressions (steps S5 and S7). However, in the case of the present embodiment, the external light / deterioration rate effect unit 26 ′ takes the difference of the external light a from the value of the light amount L measured by the optical sensor 10 by the following process, and eliminates the influence of external light. After that, the deterioration rate of each light source color is calculated (steps S9 ′ and S11).

The three relational expressions at this time are as the following expressions (26) to (28).

  The calculation of the deterioration rate performed using these relational expressions, the calculation of the light source control amount for matching the white balance with reference to the obtained minimum deterioration rate, and the control of the light source output are the same steps as in the first embodiment. According to S11, S13, S15. However, L1, L2, and L3 are L1-a, L2-a, and L3-a, respectively.

  According to the present embodiment, in addition to the same effects as those of the first embodiment, the influence of external light can be eliminated, and the white balance with time can be corrected more correctly.

  Although the amount of calculation increases in consideration of external light, the external light / deterioration rate calculation unit 26 ′ performs the following calculation to consider the influence of external light without measuring the external light. It is possible to correct the change in white balance over time. That is, the light amount of only each RGB signal is estimated from the relational expression between the RGB signal, the light amount, and external light. FIG. 11 shows a flowchart. Processing steps common to the first embodiment are denoted by the same reference numerals.

Here, the light quantity of R is x, the light quantity of G is y, the light quantity of B is z, the RGB signal at the time of scene 1 is (R4, G4, B4), and the light quantity at that time is L4. The relationship at this time is shown in Formula (29). Similarly, Expression (30) shows the relationship between the RGB signals (R5, G5, B5) and the amount of light L5 for the scene 2, and Expression (31) shows the RGB signals (R6, G6, B6) for the scene 3 and The relationship of the light quantity L6 is shown. The external light quantity is assumed to be a and constant. However, it was not measured.

Equation (32) from the difference between Equations (29) and (30), Equation (33) from the difference between Equations (29) and (31), and Equation (34) from the difference between Equations (30) and (31). Calculate (step S9-1).

As the equations are developed, the light amounts x, y, and z for R, G, and B become equations (35), (36), and (37) (step S9-2).

  Here, R4-R5 = R4 ′, G4-G5 = G4 ′, B4-B5 = B4 ′, L4-L5 = L4 ′, R4-R6 = R5 ′, G4-G6 = G5 ′, B4-B6 = B5 ', L4-L6 = L5', R5-R6 = R6 ', G5-G6 = G6', B5-B6 = B6 ', L5-L6 = L6'. Subsequent processing is the same as steps S11, S13, and S15 of the first embodiment or the fifth embodiment described above.

  By using such an arithmetic expression, although the amount of calculation increases, it is possible to correct the white balance over time by eliminating the influence without actually measuring the external light amount a.

  (Sixth Embodiment) A time-varying correction apparatus according to a sixth embodiment shown in FIG. 12 is similar to the fourth embodiment for the first embodiment. In contrast to the embodiment, an average signal value calculation unit 22-1 is provided instead of the uniform distribution determination unit 22, and a contribution storage unit 27 is further provided. In FIG. 12, other elements common to the first and fifth embodiments are denoted by the same reference numerals as those used in FIGS.

In the present embodiment, the contribution recording unit 27 stores data obtained by measuring the contribution C _ij of each pixel (i, j) of the screen 11 by the same method as in the fourth embodiment. Then, the average signal value calculation unit 22-1 calculates an average signal value in consideration of the contribution degree for any scenes 1 to 3 of the input image data. The deterioration rate calculation unit 26 ′ uses the average signal (Rt, Gt, Bt) calculated by the average signal value calculation unit 22-1 and the external light amount a and the actually measured light amount L measured by the light amount measurement unit 23 ′. The light quantity (x, y, z) of RGB is calculated by the same calculation formula as in the embodiment, the deterioration rate is calculated by comparison with the initial adjustment values (x ₀ , y ₀ , z ₀ ), and the light source control unit 21 controls the power of RGB light sources.

  In this way, in addition to the same effects as those of the fourth embodiment, it is possible to correct the white balance with time and eliminate the influence of external light as in the case of the fifth embodiment.

  (Seventh Embodiment) FIG. 13 shows the structure of a time-varying correction apparatus according to a seventh embodiment of the present invention. The present embodiment is characterized in that the brightness sensor conventionally provided in the television set is eliminated, the ambient brightness is estimated by the external light quantity measuring means, and the light source is controlled by this. That is, the temporal change correction apparatus according to the present embodiment is further adapted to the fifth embodiment shown in FIG. 8 to correct the brightness according to the ambient brightness that estimates the ambient brightness according to the external light amount. An amount calculation unit 27 is additionally provided. Thus, using the external light quantity measurement value when the power is turned on or the external light quantity measurement value for the black image at the time of video switching, in addition to the light source control for the deterioration rate, the brightness of the light source 13 is set according to the ambient brightness. Control.

  As a result, the conventionally used brightness sensor can be eliminated, and the hardware cost can be reduced correspondingly.

  Even in the third to seventh embodiments, the deterioration rate can be adjusted based on the light source control amount as in the second embodiment, and the power of the light source can be adjusted. Can be used effectively.

  The embodiment shown here is an example of the present invention and does not limit the scope of the claims of the present invention.

1 is a block diagram of a temporal change correction apparatus according to a first embodiment of the present invention. The block diagram of the projection display which employ | adopts the temporal change correction apparatus of the said embodiment. The flowchart of the white balance correction process by the said embodiment. The flowchart of the white balance correction process by the 3rd Embodiment of this invention. The block diagram of the time-dependent change correction apparatus of the 4th Embodiment of this invention. Explanatory drawing which shows the light quantity contribution distribution from each part of a screen with respect to the optical sensor employ | adopted in the said embodiment. The flowchart of the white balance correction process by the said embodiment. The block diagram of the time-dependent change correction apparatus of the 5th Embodiment of this invention. The flowchart of the white balance correction process by the said embodiment. The flowchart of the external light quantity measurement process by the said embodiment. The flowchart of the white balance correction | amendment process by the modification of the said embodiment. The block diagram of the time-dependent change correction apparatus of the 6th Embodiment of this invention. The block diagram of the time-dependent change correction apparatus of the 7th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical sensor, 11 ... Screen, 13 ... (RGB) light source, 21 ... Light source control part, 22 ... Uniform distribution determination part, 22-1 ... Average signal value calculation part, 23 ... Light quantity measurement part, 23 '... Light quantity measurement , 24 ... Initial adjustment value storage unit, 25 ... Memory, 26 ... Deterioration rate calculation unit, 26 '... External light / deterioration rate calculation unit, 27 ... Contribution storage unit, 28 ... Brightness / darkness correction amount calculation unit

Claims (5)

A light quantity measurement unit for measuring the light quantity of an image projected on a screen from a projection display using an RGB light source by an optical sensor;
A contribution storage unit for preliminarily storing the arrival contribution of light from each pixel position on the screen to the light sensor;
An average signal calculation unit that calculates an average RGB signal value using the contribution degree of each pixel of the contribution degree storage unit for the RGB signal of each pixel of the input image;
A memory for storing the light quantity measured by the optical sensor and the average RGB signal value at that time for the screen on which the input image is projected;
An initial adjustment value storage unit for storing RGB light amounts at the time of initial adjustment;
The deterioration rate is calculated by comparing each RGB light amount calculated from the relationship between the light amount stored in the memory and the average RGB signal value and the RGB light amount at the time of initial adjustment stored in the initial adjustment value storage unit. A deterioration rate calculating unit,
A light source controller that controls the output of other light source colors so as to align with the output of the light source color indicating the most advanced deterioration rate among the RGB light sources;
A projection display characterized by comprising: The projection display according to claim 1 , wherein
The light amount measurement unit measures the light amount with the optical sensor when the projection display is displaying a black image, and stores it in the memory as an external light amount,
The deterioration rate calculation unit uses the value obtained by subtracting the external light amount from the measured light amount as an actual light amount, and calculates the RGB light amounts calculated from the relationship between the actual light amount and the average RGB signal value, and the initial adjustment value storage unit. A deterioration rate is calculated by comparing with the RGB light quantity at the time of initial adjustment stored in the projection display. The projection display according to claim 2 ,
A projection display characterized in that a black image is projected upon power-on or image switching, and the external light quantity is measured by the photosensor. The projection display according to claim 2 ,
A projection further comprising: a brightness correction amount calculation unit that estimates brightness around the projection display based on the external light amount and instructs the light source control unit to perform a correction amount according to the surrounding brightness. display. In the projection display in any one of Claims 1 thru | or 4 ,
The projection display, wherein the deterioration rate calculation unit calculates a deterioration rate in consideration of a light source control amount of each of the RGB light sources.

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